presenti'i> m » Cmpclopaetita Brttaimtca: OR, A DICTIONARY OF ARTS, SCIENCES, AND MISCELLANEOUS LITERATURE; ENLARGED AND IMPROVED. THE FIFTH EDITION. jnusftcateO salt?) nearlg sir Jjunureti 3EngraWngs;. VOL. XV. INDOCTI DISCANT; AMENT MEMINISSE PERITI. EDINBURGH: Printed at the Encyclopedia Press, FOR ARCHIBALD CONSTABLE AND COMPANY, AND THOMSON BONAR, EDINBURGH GALE, CURTIS, AND FENNER, LONDON; AND THOMAS WILSON AND SONS, YORK. 1815. ii .:!'D />iAMOITO;u '•10 >a 4i a ja081M (I /iA ,830V 31')8 ,81 Jf ;3 M.IJ i7 331V .aavoi/'ii/ii ay.j. (monism: ' '< P : !1; • i- •; mtk'Wtn-2 0'j3?fUJtj tls !.8n:« tfjk'/ C^Brnt’Jlt .// .JOV .11 133q 1 A JM'i M T1521 Mi ; 'J /. A0 iKf TOO<3 . ' iiiDiiuJiKiaa t <‘J *1 V: > io fesVWJ^i • !'iu/. !•:; ,« /. >:oa KOaMOHT a K A x'f S. IM Ko:.) O ?; l. SJSAT2HOD li • (■- ■ 1 : / '( i 1 •, i ; /O'i KOJ ,fi;- y > ;, •! y / y- ; . >. •• j ' .a»OY ,8K08 aMA xI8I Encyclopaedia Britannica. Nice. N I C NicamJer "'^T* I GANDER of Colophon, a celebrated gramma- JL ’I rian, poet, and phyfician, who lived about the i6^th Olympiad, 140 years before Chrift, in the reign of Attalus king of Pergamus, who overcame the Gallo- Greeks. He lived many years in Etolia, of which country he wrote a hiftory. He wrote alfo many other works, of which only two are now remaining. The one is entitled Thenaca, defcribing in verfe the acci¬ dents attending wounds made by venomous bealts, with the proper remedies 5 the other bearing the title of A/exipharmaca, wherein he treats poetically of poifons and their antidotes. This Nicander is not to be con¬ founded with Nicander of Thyatira. NICANDRA, a genus of plants belonging to the decandna clafs •, and in the natural method ranking un¬ der the 30th order, Contorts. See Botany Index. . NICARAGUA, a large river of South America, m a. province of the fame name, whofe weltern extremi¬ ty lies within five miles of the South fea. It is full of dreadful catarads, and falls at length into the North Nicaragua, a maritime province of South Ameri¬ ca, in Mexico, bounded on the north by Honduras, on the ealt by the North fea, on the fouth-eaft by Cofta Rica, and on the fouth weft by the South fea; bein£ 400 miles in length from eaft to weft, and 120 in breadth from north to fouth. It is one of the moft fruit¬ ful and agreeable provinces in Mexico, and is well wa¬ tered with lakes and rivers. The air is wholefome and temperate; and the country produces plenty of fugar, cochineal,. and fine chocolate. One of the lakes is 200 miles m circumference, has an ifland in the middle, and as fome fay, has a tide. Leon de Nicaragua is the ca¬ pital town. 0 NIC ARI A, an ifiand of the Archipelago, between Samos and I me, about 50 miles in circumference. A chain of high mountains runs through the middle, co- vered with wood, and fupplies the country with fprings. I he inhabitants are very poor, and of the Greek com- mU”10.n* . The produaions of the ifiand are wheat, a ^NICASTRO1^’ fig'S’-!-10ne3[’ and Wax‘ Vtu, an ePlfcoPal town Laly, in the kingdom of Naples, and in the Farther Calabria ; 16 nnles ^fouth of Cofenza. E. Long. 16. 21. N. Lat. on ^iCE’an anc_Ie£t> handfome, and confiderable town countv FranCe 3nd Ita1^ and caPJtal of a Vr^^tL^ Wlth 3 ftr°ng Citadel>abi- N I C fiiop’s fee, and a fenate, which is a kind of a democra- Nice, cy. It has been feveral times taken by the French,v~lW and laft of all in 1792, but reftored after the treaty of Aix-la-Chapelle. It is very agrefeably fituated, four miles from the mouth of the river Var, 83 miles S. by W. of Turin, and 83 E. of Aix. E. Long. 6. 22. N. Lat. 43. 42. Nice, a province formerly belonging to the duke of Savoy, but now annexed to France. The inhabitants fupply Genoa with timber for building {hips ; and car¬ ry on a trade in linen cloth, paper, oil, wine, and honey. —“ Although the county of Nice be on this fide of the . mountains, geographers have always confidered it as ^dTiSL province of Italy, fince they have given to this beautiful refque De- part of Italy the river Var for a weftern limit, which \%fcription of alfo the boundary of the county, and flows into the fea^e County at a league diftance from the capital. This province is°^ ^ce' partly covered by the maritime Alps; and is bordered on the eaft by Piedmont, and the ftates of Genoa; on the fouth by the Mediterranean ; on the weft by the Var ; and on the north by Dauphiny. Its length is about 20 leagues of the country, which make about 3.6 Englifii miles ; its breadth is 10 leagues; and its popu¬ lation is about 120,coo fouls. “ T*16 city °f Nice is the capital, and the feat of the fenate, the biftiopric, and government. It has become, within thefe few years, a delightful abode, by the num¬ ber of ftrangers who afiemble there in the winter, either to re-eftablifh their health, or to enjoy the mildnefs of the climate, and the beauty of the country, where an unceafing verdure prefents eternal fpring. “ The town is fituated on the fea ftiore, and is back¬ ed by a rock entirely infulated, on which was formerly a caftle, much efteemed for its pofition ; but it was de- ftroyed in the year 1706 by Marechal Berwick, the garrifon being too thin to defend the extent of the works. There is a diftinaion between the old and the new town ; this laft is regular, the houfes are well built, and the ftreets are wide. Its pofition is by the fide of the fea, and it is terminated, on one fide, by a charmino- terrace, which ferves for a promenade. “Any perfon may live peaceably in this province, without fear of being troubled on points of faith, pro¬ vided he conducts himfelf with decorum. The town has three fuburbs. ift, That of St John, which conducts to Cimier, about three leagues north from Nice, &c/ I lie promenades this way are very delightful, and’ may be enjoyed in a carriage. 2d, That of tLe Poudriere. A 3d, NIC [2 N :ce, qd, That of the Croix de Marbre, or Marble Crofs. Nicepho- 'This fuburb is new and the Engliih almoft all lodge ‘ in it, being very near the town. The houfes are com¬ modious, facing on one fide the great road which leads to France, and on the other a fine garden, with a pro- fpeft of the fea. All the houfes are feparate from each other : the company hire them for the feafon, i. e. from October till May. Apartments may be had from 15 to 250 louis. The proprietors commonly furnilh linen, plate, &c. There are alfo in the town very large and commodious houfes •, as well as the new road, which is opened from the town to the port, by cutting that part of the rock which inclined toward the fea. The fitua- tion is delightful, and warmeit in winter, being entire¬ ly covered from the north wind, and quite open to the fouth. “ The company is brilliant at Nice, and the amufe- ments of the Carnival are, in proportion to the fize of the town, as lively as in any of the great ones in France. There is always an Italian opera, a concert and malked ball, alternately } and the company play ra¬ ther high. It is irapoflible to find a happier climate than Nice, both for fummer and winter. Reaumur’s thermometer, in 1781, never fell more than three degrees below the freezing point, and that only for two days while at Geneva it fell ten : and in the courfe of the winter of 1785 it fell only two degrees j while at Geneva it fell 15. The month of May is rarely fo fine in France as February at Nice. The fummer is not fo hot as might be expended. The thermometer never rifes more than 24 degrees (86° Fahren.) above temperate in the {hade j and there is always an agreeable fea breeze from ten in the morning till funfet, when the land breeze comes on. There are three chains of graduated mountains, the lafi of which confound their fummits with the Alps j and to this triple rampart is owing the mild tempera¬ ture fo fenfibly different from that of the neighbouring parts. “ The cultivation of the ground is as rich as can be defired. There are alternately rows of corn and beans, feparated by vines attached to different fruit-trees, the almond and the fig j fo that the earth being inceffantly cultivated, and covered tvith trees, olive, orange, ce¬ dar, pomegranate, laurel, and myrtle, caufes the con- ftant appearance of fpring, and forms a fine contrail with the fummits of the Alps, in the back ground, co¬ vered with fnow.” Nick, an ancient town of Afia, in Natolia, now cal¬ led Ifnic, with a Greek archbilhop’s fee. It is famous for the general council affembled here in 325, which endeavoured to fupprefs the doflrines of Arius. It was formerly a large, populous, and well built place, and even now is not inconfiderable. See Isnic. NlCENE Creed, was compofed and eftablifhed, as a proper fummary of the Chriilian faith, by the council at Nice in 325, againft the Arlans.—It is alfo called the Conjlantinopolitan creed, becaufe it was confirmed, with fome few alterations, by the council of Conftantinople in 381. See Creed. NICEPHORUS, Gregoras, a Greek hiftorian, was born about the clofe of the 13th century, and flou- riflred in the 14th, under the emperors Andronicus, John Pa-aeologus, and John Cantacuzenus. He w’as a great favourite of the elder Andronicus, who made him ] NIC librarian of the church of Conftantinople, and fent him Nicepho- ambaffador to the prince of Servia. He accompanied T.rus> this emperor in his misfortunes, and aflifted at his. 1Ct-^0^^ death ; after which he repaired to the court of the younger Andronicus, where he feems to have been well received ; and it is certain that, by his influence over the Greeks, that church was prevailed on to refufe en¬ tering into any conference with the legates of Pope John XXII. Rut in the difpute which arofe between Barlaam and Palamos, taking the part of the former, he maintained it zealoufly in the council that w'as held at Conftantinople in 1351, for which he wTas caft into prifon, and continued there till the return of John Pa- leeologus, who releafed him *, after which he held a dif- putation with Palamtjs, in the prefence of that emperor. He compiled a hiftory, w'hich in 11 books contains all that paffed from 1204, when Conftantinople was taken by the French, to the death of Andronicus Palaeologus the younger, in i34i«—-The beft edition of this rvork is that of the Louvre, in Greek and Latin, in 1702. Nicefhorks, Calijlus, a Greek hiftorian, rvho flou- riflied in the 14th century under the emperor Androni¬ cus Pakeologus the elder, wrote an ecclefiaftical hiftory in 23 books $ 18 of which are ftill extant, containing the tranfaftions of the church from the birth of Chrift to the death of the emperor Phocas in 610.—We have nothing elfe but the arguments of the other five books, from the commencement of the reign of the emperor Heraclius, to the end of that of Leo the Philofopher, who died in the year 911. Nicephorus dedicated his hiftory to Andronicus Palaeologus the elder. It was tranflated into Latin by John Langius } and has gone through feveral editions, the beft of which is that of Paris, in 1630. NICERON, John Francis, a French philofopher, was born at Paris in 1613. Having finiftied his acade¬ mical ftudies, with a fuccefs which raifed the greateft hopes of him, he entered into the order of the Minims, and took the habit in 1632 j and, as is ufual, he chan- fed the name given him at his baptifm for that of 'rancis, the name of his paternal uncle, who was alfo a Minim, or Francifcan. The inclination and tafte which he had for mathematics appeared early. He be¬ gan to apply himfelf to that fcience in his philofophical ftudies, and devoted to it all the time he could fpare from his other employments, after he had completed his ftudies in theology. All the branches of the mathema¬ tics, however, did not equally engage his attention ; he confined himfelf particularly to optics, and only learned of the reft as much as was neceffary for rendering him perfeft in this. There remain ftill, in feveral houfes wherein he dwelt, efpecially at Paris, fome excellent performances, which difeover his {kill in this way, and which make us regret that a longer life did not fuffer him to carry it to that perfection which he defired } finee one cannot help being furprifed that he proceeded fo far as he did, in the midft of thofe occupations and travels by which he was forced from it during the ftiort fpace of time which he lived. He hath hhnfelf obferved in the preface to his Thnumaturgus Opticus, that he went twice to Rome ; and that, on his return home, he was appointed teacher of theology. He was afterwards chofen to accompany Father Francis de la None, vicar general of the order, in his vifitation of the convents throughout all France. Eut the eagernefs NIC [ 3 ] Niceron. of his paflion for ftndy put him upon making the oeft of 1 * -v " L‘ all the moments he had to fpare for books: and that wife economy furnifhed him with as much as iatisfied him. Being taken fick at Aix in' Provence, he^ died there Sept. 22. 1646, aged 33. He was an intimate acquaintance of L)es Cartes. The following aie his principal works : VInterpretation des chifres, ou regies pour bien entendre et exphquer facilement toutes fortes des chiffres Jimples, &cc. 2. La perfpeElive cuiieufe, ou magie artificielle des effete merveilleux de l optique, cat- cptrique, et dioptnque. This is only an eflfay to the fol¬ lowing work: 3• l haumaturgus opticus^ jive^ Adnw anda opt ices, catoptrices, et dioptrices, pars prima, &c. 1 wo other parts were intended to complete the latter work, but were unfinilhed at his death. Niceron, John Peter, fo much celebrated on ac¬ count of his Memoirs of Men illuftrious in the Republic of letters, was born at Paris March 11. 1685. He was of an ancient and noble family, who were in very high repute about 1540. He fludied with fuccefs in the Mazarine college at Paris, and afterwards at the college Du Pleffis. In a fliort time, refolving to forfake the world, he confulted one of his uncles who belonged to the order of Barnabite Jefuits. This uncle examined him •, and not diffident of his ele&ion, introduced him as a probationer to that fociety at Paris.—He wras re¬ ceived there in 1702, took the habit in 1703, and made his vows in 1704, at the age of 19. After he had profefied himfelf, he was fent to Mont¬ arges, to go through a courfe of philofophy and theo¬ logy *, thence he went to Loches in Touraine to teach thofe fciences. He received the priefthood at Poitiers in 1 708. As he was not arrived at the age to aflume this order, a difpenfation, rvhich his uncommon piety had merited, was obtained in his favour. The college #f Montarges having recalled him, he was their pro- feffor of rhetoric two years, and of philofophy four.— In fpite of all thefe avocations, he was humanely attentive to every call and work of charity, and to the inllruc- tion of his fellow creatures, many of whom heard him deliver out fit rules of conduft for them, not only from the pulpits of moft of the churches within the province, but even from thofe of Paris.—In 1716, his fuperiors invited him to that city, that he might have an oppor¬ tunity of following, with the more convenience, thofe Rudies for which he always had expreffed the greateft inclination. He not only underftood the ancient but the modern languages j a circumftance of infinite advan¬ tage in the compofition of thofe works which he has given to the public, and which he carried on with great affiduxty to the time of his death, which happened, after a ffiort illnefs, July 8. 1738, at the age of 53.. His works are, 1. Le grand Febrifuge ; or, a Diflertation to prove that common water is the beft remedy in fevers, and even in the plague ; tranllated from the Englifh of John Hancock minifter of St Margaret’s, London 5 in 12mo. This little treatife made its appearance, amongft other pieces relating to this fubjeft, in 1720 j and was attended with a fuccefs which carried it through three editions-, the laft came out in 1730, in 2 vols. i2mo, entitled, A Treatife on Common Water ; Paris, print¬ ed by Cavelier. 2. The Voyages of John Ouvington to Surat, and divers parts of Afia and Africa, containing the hiftory of the revolution in the kingdom of Gol- conda, and fome obfervations upon fxlk worms j Paris, N I C 1725, 2 vols. l2tno- 3. The Converfion of England Nitron to Chrifiianity, compared with its pretended Reforma- tion, a Work tranflated from the Engliffi j Paris 1 729, __—y— 8vo. 4. The Natural Hiftory of the Earth, tranflated from the Englith of Mr Woodward, by M. Nogues, doflor in phyiic} with an anfwer to the objedtions of Dr* Camerarius ; containing alio feveral letters written on the fame fubjecl, and a methodical diftribution of foffils, tranflated from the Engliffi by Niceron j Paris, 1735, 410. 5. Memoirs of Men illuftrious in the Re¬ public of Letters, with a critical account of their works.} Paris, i2mo. The firft volume of this great work ap¬ peared in 1727 } the others were given to the public in fucceflion, as far as the 39th, which appeared in 1738. The 40th volume was publiffied after the death of the author, in 1739. , NICETAS, David, a Greek hiftorian, a native, as fome relate, of Paphlagonia, who lived about the end of the 9th centtry. He wrote The Life of St Ignatius, patriarch of Conftantinople, which was tranflated into Latin by Frederic Mutius biffiop of lermoli: he com- pofed alfo feveral panegyrics in honour of the apoftles and other faints, which are inferted in the laft continua¬ tion of the Bibliotheca Patrum by Combefis. Nicetas, furnamed Serron, deacon of the church of Conftantinople, cotemporary with Theophylaft in the IKh century, and afterwards biffiop of Heraclea, wrote a Catena upon the book of Job, compiled from pafiages of feveral of the fathers, which was printed at London in folio, 1637. We have alfo, by the fame writer, feveral catemc upon the Pfalms and Canticles, Bafil, 1552 ? together with a Commentary on the poems of Gregory Nazianzen. Nicetas, Arhominates, a Greek hiftorian of the 13th century, called Coniates, as being born at Chone, or Coloffus, in Phrygia. He was employed m feveral confiderable affairs at the court of Conftantinople} and when that city was taken by the French in 1 204, he withdrew, with a young girl taken from the enemy, to Nice in Bithynia, where he married his captive, and died in 1206. He wrote a Hiftory, or Annals, from the death of Alexius Comnenus in the year 1118, to that of Badouin in 12055 of which xvork we have a Latin tranflation by Jerome Wolfius, printed at Bafil in 1 357 } and it has been inferted in the body of the By¬ zantine Hiftorians, printed in France at the Louvre. NICHE, in ArchiteBure, a hollow funk into a wall, for the commodious and agreeable placing of a ftatue. The word comes from the Italian nechia, “ fea-fhell}” in regard the ftatue is here enclofed in a ffiell, or per¬ haps on account of the ffiell wherewith the tops of fome of them are adorned. NICHOLLS, Dr Frank, phyfician and anatomift, was born in London in the year 1699. His father was a barrifter at law } and both his parents were of good families in Cornwall. After receiving the firft rudi¬ ments of his education at a private fchool in the coun¬ try, where his docility and fweetnefs of temper endeared him equally to his mafter and his fchool fellows, Frank was in a few years removed to Weftminfter, and from thence to Oxford, where he was admitted a commoner (or fojourner) of Exeter college, under the tuition of Mr John Haviland, on March 4. 1714. There he ap¬ plied himfelf diligently to all the ufual academical ftu- dies, but particularly to natural philofophy and polite A 2 literature. NIC [ 4 ] NIC Nkholls. literature, of winch the fruits were mofl conf|)icuous in v his fubfequent lectures on phyfiology. After reading a few books on anatomy, in order to perfedt himfelf in the nomenclature of the animal parts then adopted, he en¬ gaged in diiTeftions, and then demoted himfelf to the itudy of nature, perfeftly free and unbiaffed by the opi¬ nions of others. On his being chofen reader of anatomy in that uni- verfity, he employed his utmoft attention to elevate and illuitrate a fcience which had there been long deprefled and negle&ed ; and by quitting the beaten track of former ledturers, and minutely invelligating the texture of every bowel, the nature and order of every velfel, &c. he gained a high and juft reputation. He did not then refide at Oxford j but when he had finiftied his ledtures, ufed to repair to London, the place of his abode, where he had determined to fettle. He had once an intention of fixing in Cornwall, and for a fhort time pradtifed there with great reputation ; but being foon tired of the fatigues attendant on that profefiion in the country, he returned to London, bringing back with him a great infight, acquired by diligent obferva- tion, into the nature of the miliary fever, which was attended with the moft falutary effedts in his fubfequent pradlice at London. About this time he refolved to vifit the continent, partly with a view of acquiring the knowledge of men, manners, and languages ; but chiefly to acquaint him¬ felf with the opinions of foreign naturalifts on his favou¬ rite ftudy. At Paris, by converfing freely with the learned, he foon recommended himfelf to their notice and efteem. Winflow’s was the only good fyftem of phyfiology at that time known in France, and Morgag¬ ni’s and Santorini’s of Venice in Italy, which Dr Ni- cholls likewife foon after vifited. On his return to England, he repeated his phyfiological ledfures in Lon¬ don, which were much frequented, not only by ftu- dents from both the univerfities, but alfo by many fur- geons, apothecaries, and others. Soon after, his new and fuccefsful treatment of the miliary fever, then very prevalent in the fouthern parts of England, added much to his reputation. In 1725, at a meeting of the Royal Society, he gave his opinion on the nature of aneurifms, in which he diflented from Dr Freind in his Hiftory of Phyfic. At the beginning of the year 1728, he was chofen a fellow of the Royal Society, to which he afterwards communicated the defcription of an uncommon diforder (publifhed in the Tranfadtions), viz. a polypus, refem- bling a branch of the pulmonary vein (for which Tul- pius has ftrangely miftaken it), coughed up by an afth- rnatic perfon. He alfo made obfervations (in the fame volume of the Tranfadfions) on a treatife, by M. Helve- tius of Paris, on the lungs. Towards the end of the year 1729, he took the degree of dodlor of phyfic at Oxford. At his return to London, he underwent an examination by the prefident and cenfors of the College of Phyficians, previous to his being admitted a candi¬ date, which every pradHtioner muft be a year before he can apply to be chofen a fellow. Dr Nicholls was cho- len into the college on June 26. 1732 ; and two years after, being chofen Gulftonian reader of Pathology, he made the ftrudture of the heart, and the circulation of the blood, the fubjedt of his ledfures. In 1736, at the requeft of the prefident, he again read the Gulftonian ledture j taking for his fubjedt thofe parts of the human body which ferve for the fecretion and difcharge of the urine ; and the caufes, fymptoms, and cure of the dif- eafes occafioned by the ftone. In 1739, he delivered the anniverfary Harveian oration. In 1743, he mar¬ ried Elizabeth, youngeft daughter of the celebrated Dr Mead, by whom he had five children, two of whom died young. Two fons and a daughter furvived him. In 1748, Dr Nicholls undertook the office of chirurgi- cal ledturer, beginning with a learned and elegant dif- fertation on the Ammo, Medico. About this time, on the death of Dr John Cuningham, one of the eledts of the college, Dr Abraham Hall was chofen to fucceed him in preference to our author, who was his fenior, without any apparent reafon. With a juft refentment, he immediately refigned the office of chirurgical ledfurer, and never after attended the meetings of the fellows, except when bufinefs of the utmoft importance wTas in agitation. I7Jr» lie took fome revenge in an anonymous pamphlet, entitled “ The petition of the Unborn Babes to the Cenfors of the Royal College of Phyficians of London) in which Dr Nelbit (Focus), Dr Maule (Mau'us). Dr Barrowby (Barebone), principally, and Sir William Brown, Sir Edward Hulfe, and the Scots incidentally, are the objedts of his fatire. I753> on tl16 death of Sir Hans Sloane, Bart, in his 94th year, Dr Nicholls was appointed to fucceed him as one of the king’s phyficians, and held that office till the death of his royal mafter in 1 760 $ when this moft Ikilful phyfician was fuperfeded with fomething like the offer of a penfion, which he rejedted with dif- dain. I he caufes, &c. of the uncommon diforder of which the late king died, viz. a rupture of the right ventricle of the heart, our author explained in a letter to the earl of Macclesfield, prefident of the Royal Society, which was publilhed in the Philofophical Tranfadtions, vol. 1. In 1772, to a fecond edition of his treatife De Anima Medico, he added a differtation De motu csrdis et fan- guinis in homine naio et non nato, infcribed to his learn¬ ed friend and coadjutor the late Dr Lawrence. Fired at length of London, and alfo defirous of fu- perintending the education of his fon, he removed to Oxford, where he had fpent moft agreeably fome years in his youth. But when the ftudy of the law recalled Mr Nicholls to London, he took a houfe at Epfom, where he paffed the remainder of his life in a literary retirement, not inattentive to natural philofophy, efpe- cially the cultivation of grain, and the improvement of' barren foils, and contemplating alfo with admiration the internal nature of plants, as taught by Linnaeus. His conftitution never was robuft. In his youth, at Oxford, he was with difficulty recovered from a dangerous fever by the fkill of Doflors Frampton and Frewen ; and afterwards at London he had frequently been affli&ed with a catarrh, and an inveterate afth- matic cough, which, returning with great violence at the beginning of the year 1778, deprived the world of this valuable man on January 7th, in the 80th year of his age. Dr Lawrence, formerly prefident of the college of phyficians, who gratefully afcribcd all his phyfiological and medical knowledge to his precepts, and who, while he Nicholls. ' NIC [ 5 ] NIC Nicliolls he lived, loved him as a brother, and revered him as a . II parent, two years after printed, and gave to his friends, jJicobar. ^ few COpies of an elegant Latin Life of Dr Nieholls (with his head prefixed, a ftriking likenefs, engraved by Hall from a model of Goflet, 1779) j from which, through the medium of the Gentleman’s Magazine, the above particulars are chiefly extradled. NICIAS, a celebrated painter of Athens, flourilhed about 322 years before the Chriftian era j and was uni- verfally extolled for the great variety and noble choice of his fubjects, the force and relievo of his figures, his fkill in the ditlribution of the lights and (hades, and his dex¬ terity in reprefenting all forts of four-footed animals, be¬ yond any mailer of his time. His moll celebrated piece was that of Tartarus or Hell, as it is defcribed by Ho¬ mer, for which King Ptolemy the fon of Lagus oft'ered him 60 talents, or 11,250!. which he refufed, and ge- neroully prefented it to his own country. He was much efteemed likewife by all his cotemporaries for his excel¬ lent talent in fculpture. NICKEL, a metallic fubftance ; for the nature of which, fee Chemistry Index; and for an account of its ores, fee Mineralogy Index. NICOBAR ISLANDS, the name of feveral iflands in Afia, lying at the entrance of the gulf of Bengal. The largeft of thefe iflands is about 40 miles long and 15 broad, and the inhabitants are faid to be a harmlefs fort of people, ready to fupply the ftrips that flop there with provifions. The fouth end of the great Nicobar is pla¬ ced in eaft longitude 940 23' 30" \ and we collefl from Mr Rennel’s Memoir, that it is within the 12th degree of north latitude. Of the northernmoft ifland, which is called Carnico- bar, we have, in the fecond volume of the Afiatic Re- fearches, fome interefting information refpefting both the produce and natural hiftory of the country, and the manners of its inhabitants. The author of the memoir is Mr G. Hamilton, who, in his account of this ifland, fays, “ It is low, of a round figure, about 40 miles in circumference, and appears at a diftance as if entirely covered with trees : however, there are feveral well cleared and delightful fpots upon it. The foil is a black kind of clay, and marlhy. It produces in great abun¬ dance, and with little care, molt of the tropical fruits, fuch as pine apples, plantains, papayes, cocoa-nuts, and areca-nuts ; alfo excellent yams, and a root called cachu. The only four-footed animals upon the ifland are, hogs, dogs, large rats, and an animal of the lizard kind, but large, called by the natives tolonqui; thefe frequently carry off fowls and chickens. The only kind of poul¬ try are hens, and thofe not in great plenty. There are abundance of fnakes of many different kinds, and the inhabitants frequently die of their bites. The timber upon the ifland is of many forts, in great plenty, and fome of it remarkably large, affording excellent mate¬ rials for building or repairing (hips. “ 1 he natives are low in llature, but very well made, and furprifingly aftive and ftrong ; they are copper-co¬ loured, .and their features have a call of the Malay, quite the reverfe of elegant. The women in particular are extremely ugly.. The men cut their hair fhort, and the women have their heads fliaved quite bare, and wear no covering but a Ihort petticoat, made of a fort of rulh or dry grafs, which reaches half way down the thigh. I his grafs is not interwoven,, but hangs round the per- I fon fomething like the thatching of a houfe. Such of them as have received prefents of cloth petticoats from the {hips, commonly tie them round immediately under the arms. The men wear nothing but a narrow {trip of cloth about the middle, in which they wrap up their pri¬ vities fo tight that there hardly is any appearance of them. The ears of both fexes are pierced when young j and by fqueezing into the holes large plugs of wood, or hanging heavy weights of fliells, they contrive to ren¬ der them wide, and difagreeable to look at. They are naturally dilpofed to be good humoured and gay, and are very tond of fitting at table with Europeans, where they eat every thing that is fet before them ; and they eat moll enormoully. They do not care much for wine, but will drink bumpers ©f ai'ack as long as they can fee. A great part of their time is fpent in feafting and dan¬ cing. W hen a fealt is held at any village, every one that choofes goes uninvited, for they are utter fl rangers to ceremony. At thofe featls they eat immenfe quanti¬ ties of pork, which is their favourite food. Their hogs are remarkably fat, being fed upon the cocoa-nut ker¬ nel and fea water ; indeed all their domeftic animals, fowls, dogs, &c. are fed upon the fame. They have likewife plenty of fmall fea filh, which they ftrike very dexteroufly with lances, wading into the fea about knee deep. They are fure of killing a very fmall filh at 10 or 12 yards diltance. • 'l hey eat the pork almoft raw, giving it only a hafty grill over a quick fire. They roaft a fowl, by running a piece of wood through it, by way of fpit, and holding it over a brilk fire until the feathers are burnt off, when it is ready for eating, in their tafte. They never drink water ; only cocoa-nut milk, and a liquor called /oura which oozes from the cocoa-nut tree after cutting off the young fprouts or flowers. This they fuffer to ferment before it be ufed, and then it is intoxicating ; to which quality they add much by their method of drinking it, by fucking it flowly through a fmall ftraw. After eating, the young men and women, who are fancifully dreffed with leaves, go to dancing, and the old people furround them fmok- ing tobacco and drinking /oura. The dancers, while performing, fing fome of their tunes, which are far from wanting harmony, and to which they keep exa& time. Of mufical inftruments they have only one kind, and that the fimpleft. It is a hollow bamboo about two feet and a half long and three inches in diameter, along the outfide of which there is ftretched from end to end a Angle firing made of the threads of a fplit cane, and the place under the firing is hollowed a little to prevent it from touching. This inftrument is played upon in the fame manner as a guitar. It is capable of produ¬ cing but few notes •, the performer, however, makes it fpeak harmonioufly, and generally accompanies it with the voice. “ Their houfes are generally built upon the beach, in villages of 15 or 20 houfes each ; and each houfe contains a family of 20 perfons and upwards. Thefe habitations are raifed upon wooden pillars about 10 feet from the ground ; they are round, and, having no win¬ dows, are like bee-hives, covered with thatch. The. entry is through a trap door below, where the family mount by a ladder, which is drawn up at night. This manner of building is intended to fecure the houfes from being infefted with fnakes and rats j and for that pur- pofe the pillars are bound round with a fmooth kind of . leaf, j Nicobar. NIC [ 6 ] NIC Nicobar. leaf5 •nObich prevents animals from being able to mount : 'v befides which, each pillar has a broad round flat piece of wood near the top of it, the projecting of which ef¬ fectually prevents the further progrefs of fuch vermine as may have paffed the leaf. The flooring is made with thin ftrips of bamboos, laid at fuch diftances from one another as to leave free admifllon for light and air ; and the irifide is neatly finiflied and decorated with tith¬ ing lances, nets, &c. “ The art of making cloth of any kind is quite un¬ known to the inhabitants of this ifland ; what they have is got from the thips that come to trade in cocoa- nuts. “ They purchafe a much larger quantity of cloth than is confumed upon their own ifland. This is in¬ tended for the Choury market. Choury is a fmall ifland to the fouthward of theirs, to which a large fleet of their boats fails every year about the month of Novem¬ ber, to exchange cloth for canoes j for they cannot make thefe themfelves. This voyage they perform by the help of the fun and ftars, for they know nothing of the compafs. “ In their difpofition there are two remarkable qua¬ lities. One is their entire negleCt of compliment and ceremony 5 and the other, their averfion to diflionelty. A Carnicobarian travelling to a diftant village, upon bufinefs or amufement, paffes through many towns in his way without fpeaking to any one ; if he is hungry or tired, he goes into the nearefl: houfe, and helps him- felf to what he wants, and fits till he is refted, without taking the fmalleft notice of any of the family unlefs he has bufinefs or news to communicate. Theft or robbery is fo very rare amongft them, that a man going out of his houfe never takes away his ladder or fhuts his door, but leaves it open for any body to enter that pleafes without the leaf! apprehenfion of having any thing ftolen from him. “ Their intercourfe with flrangers is fo frequent, that they have acquired in general the barbarous Portuguefe fo common over India 5 their own language has a found quite different from moft others, their words being pro¬ nounced with a kind of flop, or catch in the throat, at every fyllable. “ They have no notion of a God, but they believe firmly in the devil, and worfhip him from fear. In every village there is a high pole ereCted with long firings of ground rattans hanging from it, which, it is faid, has the virtue to keep him at a diflance. When they fee any figns of an approaching ftorm, they ima¬ gine that the devil intends them a vifit, upon which many fuperftitious ceremonies are performed. The people of every village march round their own boun¬ daries, and fix up at different diftances fmall fticks fplit at the top, into which fplit they put a piece of cocoa nut, a whifp of tobacco, and the leaf of a cer¬ tain plant •, whether this is meant as a peace offering to the devil or a fcarecrow to frighten him away, does not appear. “ When a man dies, all his live ftock, cloth, hatchets, fifhing lances, and in fhort every moveable thing he poffeffed, is buried with him, and his death is mourn¬ ed by the whole village. In one view this is an excel¬ lent cuftom, feeing it prevents all difputes about the property of the deceafed amongft his relations. His wife mull conform to cuftom by having a joint cut off from 2 one of her fingers* and if Ihe refufes this, fin* mull fubmit to have a deep notch cut in one of the pillars of her houfe. “ I was once prefent at the funeral of an old woman. When we went into the houfe which had belonged to the deceafed, we found it full of her female rela¬ tions ; fome of them were employed in wrapping, up the corpfe in leaves and cloth, and others tearing to pieces all the cloth Which had belonged to her. In another houfe hard by, the men of the village with a great many others from the neighbouring towns, were fitting drinking fuut'a and fmoking tobacco. In the mean time two flout young fellows were bufy digging a grave in the fand near the houfe. When the women had done with the corpfe, they fet up a moft hideous howl, upon which the people began to affemble round the grave, and four men went up into the houfe to bring down the body 5 in doing this they were much interrupted by a young man, fon to the deceafed, who endeavoured with all his might to prevent them ; hut finding it in vain, he clung round the body, and was carried to the grave along with it: there, after a violent ftruggle, he was turned away and conducted back to the houfe. The corpfe being now put into the grave, and the lafhings which bound the legs and arms cut, all the live ftock which had been the property of the deceafed, confifting of about half a dozen hogs, and as many fowls, was killed, and flung in above it j a man then approached with a bunch of leaves ftuck upon the end of a pole, which he fwept two or three times gently along the corpfe, and then the grave was filled up. During the ceremony, the women continued to make the moft horrible vocal concert imaginable : the men faid nothing. A few days afterwards, a kind of monu¬ ment was erected over the grave, with a pole upon it, to which long ftrips of cloth of different colours were hung. “ Polygamy is not known among them j and their punilhment of adultery is not lefs fevere than effectual. They cut, from the man’s offending member, a piece of the forelkin proportioned to the frequent com mi f- fion or enormity of the crime. “ There feems to fubfift among them a perfect equa¬ lity. A few perfons, from their age, have a little more refpeft paid to them j but there is no appear¬ ance of authority one over another. Their fociety feems bound rather by mutual obligations continually conferred and received ; the fimpleft and heft of all ties.” It is our wifti to take all opportunities of laying before our readers every authentic fa£t which can throw light upon the philofophy of the human mind. In this narrative of Mr Hamilton’s refpefting the na¬ tives of Carnicobar, there is however one circumftance at which we ftumble. It is known to the learned, that the philofophers of Greece and Rome, as well as the magi of Perfia, admitted two felf-exiftent beings, a good and an evil (fee Polytheism) ; but we never before read of any people who had no notion of a God, and yet firmly believed in the devil. We could give inftances of men worfliipping the evil principle from fear, and neglecting the worfliip of the benevo¬ lent principle from a perfuafion that he would do them all the good in his power without being bribed by fa- crifices Nicobar. 1 NIC [ 7 3 NIG JsTicobar. orifices and oblations ; but this is the only mftance of mm—if— which we have ever heard, of a people, under the in¬ fluence of religion, who had no notion of a God. As good is at leaft as apparent in the world as evil, it ap¬ pears to us fo very unnatural to admit an evil and de¬ ny a good principle, that we cannot help thinking that Mr Hamilton, from his ignorance of the language of Carnicobar, (which he acknowledges to be dift'erent from moft others), has not a perfeft acquaintance with the religious creed of the natives : and that they be¬ lieve in a good as well as in an evil principle, though they worlhip only the latter, from a perfuafion, that to adore the former could be of no advantage either to him or to themfelves. Nancowry or Soury, and Comerty, two other of the Nicobar iflands, are faid to be the belt peopled, con¬ taining not lefs than 800 inhabitants. Between thefe iflands there is a fafe and fpacious harbour. On the north point of Nancowry, within the harbour, the Danes have long retained a fmall fettlement, protected by a fergeant and a few foldiers and flaves. NICODEMUS, a difciple of Jefus Chrift, a Jew by nation, and by feft a Pharifee (John iii. 1. &c.) The Scripture calls him a ruler of the Jews, and our Saviour gives him the name of a mailer of Ifrael. When our Saviour began to manifell himfelf by his miracles at Jerufalem, at the firft paffover that he ce¬ lebrated there after his baptifm, Nicodemus made no doubt but that he was the Mefliah, and came to him by night, that he might learn of him the way of fal- vation. Jefus told him, that no one could fee the kingdom of heaven except he Ihould be born again. Nicodemus taking this in the literal fenfe, made an- fwer, “ How can a man that is old be born again ? Can he enter the fecond time into his mother’s womb ?” To which Jefus replied, “ If a man be not born of water and of the fpirit, he cannot enter into the kingdom of God. That which is born of the flelh is flefli, and that which is born of the fpirit is fpirit.” Nieodemus alks him, “ How can thefe things be ?” Jefus an- fwered, “ Are you a mailer of Ifrael, and are you ig¬ norant of thefe things ? We tell you what we know, and you receive not our teftimony. If you believe not common things, and which may be called earthly, how will you believe me if I fpeak to you of heavenly things ? Nobody has afcended into heaven but the Son of God, who came down from thence. And jull as Mofes lifted up the brazen ferpent in the wildernefs, lb mull the Son of Man be lifted up on high. For God fo loved the world that he has given his only Son, fo that no man who believes in him lhall perilh, but fliall have eternal life.” After this converfation Nicodemus became a difci¬ ple of Jefus Chrilt 5 and there is no doubt to be made, but he came to hear him as often as our Saviour came to Jerufalem. It happened on a time, that the priefts and Pharifees had fent officers to feize Jefus (John vii. 45. See.), who returning to them, made their report, that never man fpoke as he did •, to which the Pharifees replied, “ Are you alfo of his difciples ? Is there any one of the elders or Pharifees that have believed in him ?” Then Nicodemus thought himfelf obliged to make anfwer, faying, “ Does the law permit us to con¬ demn any one before he is heard ?” To which they re¬ plied, “ Are you alfo a Galilean ? Read the Scrip¬ tures, and you will find that never any prophet came Nicodemus out of Galilee.” After this the council was difmifled. . W At lalt Nicodemus declared himfelf openly a difciple of )]ic&l:^c-eS; Jefus Chrift (7r/. xix. 39, 40.), when he came with Jo- feph of Arimathea to pay the laft duties to the body of Chrift, which they took down from the crofs, embalmed, and laid in a fepulchre. We are told, that Nicodemus received baptifm from the difciples of Chrift } but it is not mentioned whe¬ ther before or after the paffion of our Lord. It is added, that the Jews being informed of this, depofed him from his dignity of fenator, excommunicated him, and drove him from Jerufalem : but that Gamaliel, who was his coufin-german, took him to his country houfe, and maintained him there till his death, when he had him buried honourably near St Stephen. There is ftill extant an apocryphal gofpel under the name of Nicodemus, which in fome manuferipts bears the title of the Adis of Pilate. NICOLAITANS, in church hiftory, Chriftian he¬ retics, who aflumed this name from Nicholas of An¬ tioch ; who, being a Gentile by birth, firft embraced Judaifm and then Chriftianity \ when his zeal and de¬ votion recommended him to the church of Jerufalem, by whom he wras chofen one of the firft deacons. Many of the primitive writers believe that Nicholas was ra¬ ther the occafion than the author of the infamous prac¬ tices of thofe who aflumed his name, who wrere exprefsly condemned by the Spirit of God himfelf, Rev. ii. 6. And indeed their opinions and aftions were highly ex¬ travagant and criminal. They allowed a community of wives, and made no diftindlion between ordinary meats and thofe offered to idols. According to Eufe- bius, they fubfifted but a ffiort time $ but Tertullian fays that they only changed their name, and that their here- fies palled into the fedl of the Cainites. NICOLAS, St, an ifland of the Atlantic ocean, and one of the moft confiderable of thofe of Cape Verd, ly¬ ing between Santa Lucia and St Jago. It is of a trian¬ gular figure, and about 75 miles in length. The land is ftony, mountainous, and barren ; there are a great many goats in a valley inhabited by the Portuguefe. W. Long. 33- 35- N. Lat. 17. o. NICOLO, St, the moft confiderable, ftrongeft, and bell peopled of the ifles of Tremeti in the gulf of Ve¬ nice, to the call of St Domino, and to the fouth of Cap- parata. It has a harbour defended by feveral towers j and a fortrefs, in which is an abbey, with a very hand- fome church. E. Long. 15. 37. N. Lat. 42. 10. NICOMEDES, the name of feveral kings of the ancient Bithynia. See Bithynia. Nicodemes I. had no fooner taken poffeffion of his father’s throne, before Chrift 270, than, according to the cuftom which has in all ages been too prevalent among the defpots of the call, he caufed two of his brothers to be put to death. The youngefl, Ziboeas, having faved himfelf by timely flight, feized on the coaft of Bithynia, which was then known by the names of Thracia Thyniccia, and Thracia Afiatica, and there maintained a long war with his brother. Nicomedes being informed that Antiochus Soter, king of Syria, was making great prt parations to attack him at the fame time, called in the Gauls to his affiftance 5 and on this occafion that people firft pafied into Alia.— Nicomedes _..ving with their affiftance repulled Antio- NIC [ Nlcomedes. chus, overcome his brother, and acquired the poffef- v fion of all his father’s dominions, beftowed upon them that part of Alia Minor which from them was called Gal/o-Grtecia, and Gallatia. Having now no enemies to contend with, he applied himfelf to the enlarging and adorning of the city of Aftacus, which he called after his own name Ntcomedia. He had two wives, and by one of them he was perfuaded to leave his kingdom to her fon, in preference to his elder bro¬ thers j but when or how he died is not certainly known. NicoMEDES II. the grandfon of the former, began his reign like him, by facrificing his brothers to his jealoufy, after having waded to the throne in the blood of Prufias his father. He aflumed the name of Epi- phanes, or “ the Illultrious,” though he performed no¬ thing worthy of this title, or even of notice, during the whole time of his long reign. He was fucceeded by his Ton Nicomedes III. furnamed, by antiphrafis, Philopa- ter, becaufe he had murdered his father to get poflef- fion of his crown. This monarch having entered into alliance with Mithridates the Great king of Pontus, invaded Paphlagonia *, and having feized on that coun¬ try, he attempted likewife to make himfelf mailer of Cappadocia. This country, however, was at that time fubjeft to his powerful ally ; who thereupon marching into Bithynia at the head of an army, drove Nico- medes from the throne, and railed his brother Socrates to it in his room. The dethroned prince had recourfe to the Romans, who expelled .the ufurper, and reftor- ed him to his hereditary dominions. For this favour they preffed him, and at length prevailed upon him, contrary to his own inclination, and the opinion of his friends to make inroads into the territories of Mithri¬ dates, with whom Rome wanted a fubje£t of difpute. The king of Pontus bore for fome time the devafta- tions committed by Nicomedes with great patience, that he might not feem to be the aggreffor *, but at lall he routed his army on the banks of the Am- nius, drove him a fecond time from his dominions, and obliged him to feek for fhelter in Paphlagonia, where he led a private life till the time of Sylla, who replaced him on the throne. He was fucceeded by his fon Nicomedes IV. who performed nothing which the many writers who flourilhed in his time have thought worth tranfmitting to polferity. As he died without iffue male, he left his kingdom by his lall will to the Romans, who reduced it to the form of a province. Sallull, difagreeing with the ancients, tells us, that Ni¬ comedes left a fon named Mufa or My fa ; and introdu¬ ces Mithridates as complaining of the Romans to Ar- faces king of Parthia, for feizing on the kingdom of Bithynia, and excluding the fon of a prince who had on all occafions fhown himfelf a Heady friend to their republic. But this Mufa was the daughter and not the fon of Nicomedes, as we are told in exprefs terms by Suetonius, Velleius Paterculus, and Appian. All we know of her is, that upon the death of her father Ihe claimed the kingdom of Bithynia for her fon, as the next male heir to the crown, but without fuccefs } no motives of juftice being of fuch weight with the ambitious Romans as to make them part with a king¬ dom. 8 ] NIC N1COMEDIA, in Ancient Geography, a metropolis Nicomedla of Bithynia, built by Nicomedes the grandfather of Pru- .11 lias. It is fituated on a point of the Sinus Altacenus,. Kik_ori' . (Pliny) ; furnamed the Beautiful, (Athenseus) : the " “ large it city of Bithynia, (Paufanias), who fays it was formerly called Aflacus; though Pliny diftinguiihes Aftacum and Nicomedia as different cities. Nicome- dia was very famous, not only under its own kings, but under the Romans : it was the royal reiidence of Dio- clefian, and of Conl'lantine while Conllantinople Avas building, if we may credit Nicephorus. It is Hill called Nicomedia, at the bottom of a bay of the Propontis in the Hither Afia. E. Long. 30. o. N. Lat. 41. 2c. It is a place of confequence ; carries on a trade in filk, cot¬ ton, glafs, and earthen ware, and is the fee of a Greek archbiihop. NICOMEDUS, a geometrician, famous on ac¬ count of the invention of the curve called conchoid, Avhich is equally ufeful in refolving the two problems of doubling the cube and trifedling the angle. It appears that he lived foon after Eratofthenes, for he rallied that philofopher on the mechanifm of his mefo- labe. Geminus, who lived in the fecond century be¬ fore Jefus Chrift, has written on the conchoid, though Nicomedus was ahvays efteemed the inventor of it,- Thofe who place him four or five centuries after Jefus Chrift muft be ignorant of thefe fadls, by which we arc enabled to afeertain pretty nearly the time in which he lived. NICON, a native and patriarch of Rufiia, was born in 1613, in a village of the government of Niftmei No- vogorod, of fuch obfeure parents, that their names and ftation are not tranfmitted to pofterity. He received at the baptifmal font the name of Nikita, which after- wards, when he became monk, he changed to Nicon, the appellation by Avhich he is more generally known. He was educated in the convent of St Macarius, under the care of a monk. From the courfe of his ftudies, which Avere almoft folely dire&ed to the Holy Scrip¬ tures, and the exhortations of his preceptor, he im¬ bibed at a very early period the ftrongeft attachment to a monaftic life j and Avas only prevented from fol¬ lowing the bent of his mind by the perfuafions and authority of his father. In conformity, hoAvever, to the Avilhes of his family, though contrary to his own inclination, he entered into matrimony •, and, as that ftate precluded him from being admitted into a con¬ vent, he Avas ordained a fecular prieft. With his wife he continued ten years, partly in the country, and partly at MoIcoav, officiating as a pariffi prieft. The lofs of three children, hoAvever, gave him a total dif- guft to the world 5 in confequence of which, his wife Avas perfuaded to take the veil, and he became a monk j his retreat Avas in an ifland of the White fea, and a kind of ecclefiaftical eftablilhment Avas formed, as re¬ markable for the aufterities of its rules as the fituation Avas for its folitude. There Avere about 1 2 monks, but they all lived in different cells. Such a fyftem, com¬ bined with the moft gloomy ideas, occalioned fo much cloiftered pride as tarnilhed his chara6ler, when he Avas afterAvards called up to fulfil the duties of a pub¬ lic and exalted ftation. Our limits do not permit us to be minute in our account of his life, avc muft there¬ fore be contented Avith barely reciting general fafts. Within lefs than the fpace of five years, Nicon Avas fucceffively NIC t 9 ] NIC Nicon fucceHively created archimandrite, or abbot of the No- was called Nicotmna, but is now more generally known Jl vofpatlkoi convent, archbilhop of Novogorod, and pa- by the name of Tobacco. He died at Paris in l< 03. '‘ot' . triarch of Ruflia. That be was worthy of thefe rapid He wrote a French and Latin dictionary in folio 5 a promotions, few will doubt who are acquainted with treatife on navigation •, and other works, his charafter ; for he was poffelfed of very extraordi- NICO IT AN A, Tobacco, a genus of plants belong- nary qualities, fuch as even his enemies allow and ad- ing to the pentandria clafs, and in the natural method / mire. His courage was undaunted, his morals,irre- ranking under the 28th order, Luridce. See Botany proachable, his charity exteniive and exalted, his learn- Index.—There are feven fpecies, of rvhich the molt re- ing deep and comprehenfive, and his eloquence com- markable is the tabacum, or common tobacco plant, manding. When archbifliop, he obtained the refpect This was firit difcovered in America by the Spaniards of the inhabitants by his unwearied adiduity in the dif- about the year 1560, and by them imported into Eu- charge of his truft ; and conciliated their affe&ions by rope. It had been ufed by the inhabitants of America adts of unbounded charity : Nor was he lefs confpicuous long before j and was called by thofe of the iflands yoliy in the difcharge of the office of patriarch, to which and by the inhabitants of the continent. It was dignity he was appointed in 1652, in the 39th year of fent into Spain from Tabaco, a province of Yucatan, his age. where it was firft difcovered, and from whence it takes Nor was he only diftinguiffied in his own profeffion, its common name. Sir Walter Raleigh, it is generally for he ffione even as a ftatefman. At length, however, faid, firft introduced it into England about the year he fell a vi6tim to popular difcontents j which misfor- 1585, and taught his countrymen how to ufe it. Dr tune, though he was far from deferving it, was certainly Cotton Mather, however, (in his Chriftian Philofo- the effect of imprudence. He abdicated the office of pher) fays, that in the above year one Mr Lane car- patriarch, which would otherwife have been taken from ried over fome of it from Virginia, which was the firft him, in July 1658, and bore his reverfe of fortune time it had ever been feen in Europe. Tobacco is com- with heroic magnanimity: he -eturned to a cell, and monly ufed among the oriental nations, though it is un¬ commenced his former aufterities. His innocence, certain by whom it was introduced among them. Con- however, could not proteft him from further malice : his fiderable quantities of it are cultivated in the Levant, enemies obtained him to be formally depofed in 1666. on the coafts of Greece and the Archipelago, in Italy, This degradation was followed by imprifonment, which and in the ifland of Malta. was for fome time very rigorous, becaufe he, eonfeious There are two varieties of that fpeeies of nicotiana of his own innocence, refufed to accept pardon for which is cultivated for common uie, and which are crimes of which he was not guilty. In 1676, how- diftinguifticd by the names of Oronokoe, and fweet- ever, he was removed to the convent of St Cyril, and feented tobacco. They differ from each other only in enjoyed perfect liberty. the figure of their leaves ; thofe of the former being Nicon furvived his depofition 15 years. In 1681, longer and narrower than the latter. They are tall he requefted and obtained permiffion to return to the herbaceous plants, growing eredl with fine foliage, convent of Jerufalem, that he might end his days in : and rifing with a-ftrong ftem from fix to nine feet high, that favourite fpqt/, but he expired upon the road The ftalk near the root is upward of an inch dia- near Yaroflaf, in the 66th year of his age. His re- meter, and furrounded with a kind of hairy or velvet mains were tranfported to that convent, and buried clammy fubftance, of a yellowiftr green colour. The with all the ceremonies ufed at the interment of pa- leaves are rather of a deeper green, and grow alternately triarchs. at the diftance of two or three inches from each other. NICOPOLI, a town of Turkey in Europe, and in They are oblong, of a fpear-fhaped oval, and fimple ; Bulgaria, famous for being the place where the firit the largeft about 20 inches long, but decreafing in battle wras fought between the Turks and Chriitians fize as they afeend, till they come to be only 10 inches in 1396-, and where the latter were defeated with long, and about half as broad. The face of the leaves the lofs of 20,000 men. E. Long. 25. 33. N. Lat. is much corrugated, like thofe of fpinage when full 43- 46. ripe. Before they come to maturity, when they are NICOSIA, the capital of the ifland of Cyprus, about five or fix inches long, the leaves are generally where a Turkifh baihaw refidcs. It is delightfully of a full green, and rather fmooth ; but as they in- fituated between the mountains of Olympus and a creafe in fize, they become rougher, and acquire a chain of others, and was formerly well fortified by the yellowilh cart. The ftem and branches are terminated Venetians ; but the works are now in ruins. It is by large bunches of ilowers collected into clufters, of about 31 miles in circumference 5 and there are plan- a delicate red ; the edges, when full blown, inclining tations of olives, almonds, lemons, oranges, mulber- to a pale purple. They continue in fucceffion till the nes, and cyprefs trees, interfperled among the houfes, end of the fummer ; when they are fucceeded by feeds which give the town a delightful appearance. The of a brown colour, and kidney-fhaped. Thefe are very church of Sandla Sophia is an old Gothic ftrudture, fmall, each capfule containing about 1000; and the which the Turks have turned into a mofque, and de- whole produce of a fingle plant is reckoned at about ftroyed the ornaments. It is loo miles weft of Tri- 330,000. The feeds ripen in the month of September, poli, and 160 fouth-weft of Aleppo. E. Long. 34. Mr Carver informs us, that the Oronokoe, or, as 45. N.^ Lat. 34. 34. ft is called, the long Virginian tobacco, is the kind be ft NIC01, John, lord of Villemain, and mafter of fuited for bearing the rigour of a northern climate, the requefts of the French king’s houiehold, was born at ftrength as well as the feent of the leaves being greater Nifmes, and was fent ambaffador to Portugal in 1359 $ than that of the other. The fweet-feented fort flcu- whenee he brought the plant which, from his name, riihes molt in a Tandy foil, and in a warm climate. A ol. XV. Part I. B where Nicot, Nicotiana. NIC [ io ] NIC Nieotiana. where it greatly exceeds the former in the celerity of k“*"~v its growth ; and is likewife, as its name intimates, much more mild and pleafant. Culture.—Tobacco thrives beft in a warm, kindly, rich foil, that is not fubjedt to be overrun by weeds. In Virginia, the foil in which it thrives belt is warm, light, and inclining to be fandy 5 and therefore, if the plant is to be cultivated in Britain, it ought to be planted in a foil as nearly of the fame kind as pofiible. Other kinds of foil might probably be brought to fuit it, by a mixture of proper manure 5 but we mull remember, that whatever manure is made ufe of, muft be thoroughly incorporated with the foil. The bed fituation for a to¬ bacco plantation is the fouthern declivity of a hill, ra¬ ther gradual than abrupt, or a fpot that is (heltered from the north winds : but at the fame time it is neceflary that the plants enjoy a free air ; for without that they will not profper. As tobacco is an annual plant, thofe who intend to cultivate it ought to be as careful as poflible in the choice of the feeds ; in which, however, with all their care, they may be fometimes deceived. The feeds are to be fown about the middle of April, or rather fooner in a forward feafon, in a bed prepared for this purpofe of fuch foil as has been already defcribed, mixed with fome warm rich manure. In a cold fpring, hot beds are mod eligible for this purpofe, and gar- Treatife on deners imagine that they are always neceffary : but /7;c Culture iyfr Carver tells us, that he is convinced, when the '■J ■['lj‘jacco- weather is not very fevere, the tobacco feeds may be raifed without doors j and for this purpofe gives us the following directions. “ Having fown the feed in the manner above di¬ rected, on the lead apprehenlion of a frod after the plants appear, it will be neccflary to fpread mats over the beds, a little elevated from the ground by poles laid acrofs, that they may not be crufhed. Thefe, however, mud be removed in the morning, foon after the fun appears, that they may receive as much benefit as pofiible from its warmth and from the air. In this manner proceed till the leaves have attained about two inches in length and one in breadth } which they will do in about a month after they are fown, or near the middle of May, when the frods are ufually at an end. One invariable rule for their being able to bear removal is, when the fourth leaf is fprouted, and the fifth juft appears. Then take the opportunity of the firft rains or gentle fhowers to tranfplant them into fuch a foil and fituation as before defcribed ; which muft be done in the following manner.—The land muft be ploughed, or dug up with fpades, and made as mellow and light as poflible. When the plants are to be placed, raife with the hoe fmall hillocks at the dif- tance of two feet or a little more from each other, ta¬ king care that no hard fids or lumps are in it \ and then juft indent the middle of each, without drilling holes, as for fome other plants. “ When your ground is thus prepared, dig in a gentle manner from their native bed fuch plants as have attained the proper growth for tranfplanting above mentioned •, and drop, as you pafs, one on every hillock. Infert a plant gentry into each centre, prefling the foil around gently with your fingers ; and taking the greateft care, during the operation, that you do not break off any of the leaves, which are at this time exquifitely tender. If the weather proves dry after they are thus tranfplanted, they muft be watered with foft water, in the fame manner as is ufually done to cole worts, or plants of a fimilar kind. But though you now feem to have a fufficient quantity of plants for the fpace you intend to cultivate, it is yet neceffary that you continue to attend to your bed of feedlings, that you may have enough to fupply any deficiencies which through accident may arile. From this time great care mud be taken to keep the ground foft and free from wreeds, by often ftirring with your hoe the mould round the roots j and to prune off the dead leaves that fometimes are found near the bottom of the ftalk. “ The difference of this climate from that in which I have been accuftomed to obferve the progrefs of this plant, will not permit me to direct with certainty the time which is mod proper to take off the top of it, ta prevent it from running to feed. This knowledge carr only be acquired by experience. When it has rifen to the height of more than two feet, it commonly be¬ gins to put forth the branches on which the dowers and feeds are produced ; but as this expanfion, if dif¬ fered to take place, would drain the nutriment from the leaves, which are the mod valuable part, and there¬ by leflen their dze and efficacy, it becomes needful at this ftage to nip off the extremity of the dalk to pre¬ vent its growing higher. In fome other climates, the top is commonly cut off when the plant has 15 leaves j but if the tobacco is intended to be a little ftronger than ufual, this is done when it lias only 13 $ and fometimes, when it is defigned to be remarkably powerful, 11 or 12 are only allowed to expand. On. the contrary, if the planter is defirous of having his crop very mild, he differs it to put forth 18 or 20 : but in this calculation, the three or four lower leaves next the ground, which do not grow fo large and fine as the others, are not to be reckoned. “ This operation, denominated topping the tobacco, is much better performed by the finger and thumb than with any inftrument ; becaufe the grafp of the fingers clofes the pores of the plant 5 whereas, when it is done by inftruments, the juices are in fome degree exhauft- ed. Care muft alfo be taken to nip off the fprouts that will be continually fpringing up at the junfiion of the leaves with the ftalks. This is termed fuccouring, or fuckering, the tobacco \ and ought to be repeated as of¬ ten as occafion requires. “ As it is impoffible to afeertain the due time for topping the plant, fo it is equally irr.podible, without experiment, to afeertain the time it will take to ripen in this country. The apparent figns of its maturity are thefe : The leaves, as they approach a date of ripe- nefs, become more corrugated or rough \ and when fully ripe, appear mottled with yellowifh fpots on the railed parts } whilft the cavities retain their ufual green colour. They are at this time alfo thicker than they have been before } and are covered with a downy velvet, like that formerly mentioned, on the ftalks. If heavy rains happen at this critical period, they will waff off this excrefcent fubftance, and thereby damage the plants. In this cafe, if the frofty nights are not begun, it is proper to let them (land a few days longer ; when, if the weather be moderate, they will recover this fub¬ ftance again. But if a froft unexpectedly happens du¬ ring N NIC [i Nicotiana. ring tlie night, they muft be carefully examined in the '-“-V—morning, before the fun has any influence upon them j and thofe which are found to be covered with frofty particles, whether thoroughly ripe or not, muft be^ cut -up } for though they may not all appear to be arrived at a ftate of maturity, yet they cannot be far from it, and will differ but little in goodnefs from thofe that are perfectly fo.” Tobacco is fubjeft to be deflroyed by a worm-, and without proper care to exterminate this enemy, a whole field of plants may foon be loft. This animal is of the horned fpecies, and appears to be peculiar to the tobacco plant; fo that in many parts of America it is diftinguifhed by the name of the tobacco worm. In what manner it is firft produced, or how propagated, ■is unknown c but it is not difcermble till the plants have attained about half their height } and then ap¬ pears to be nearly as large as a gnat. Soon after this it lengthens into a worm and by degrees increafes in magnitude to the bignefs of a man’s finger. In fhape it is regular from its head to its tail, without any di¬ minution at either extremity. It is indented or ribbed round at equal diftances, nearly a quarter of an inch from each other ; and having at every one of thefe di- vifions a pair of feet or claws, by which it faftens itfelf to the plant. Its mouth, like that of the caterpillar, is placed under the fore part of the head. On the top of the head, between the eyes, grows a horn about half an inch long, and greatly refembling a thorn; the ex¬ treme part of which is of a brown colour, a firm tex¬ ture, and the extremity fliarp pointed. It is eafily crulhed ; being only, to appearance, a colle&ion of green juice enelofed in a membranaceous covering, without the internal parts of an animated being. The colour of its {kin is in general green, interfperfed with feveral fpots of a yellowiftt white ; and the whole co¬ vered with a fliort hair fcarcely to be difcerned. Thefe worms are found the moft predominant during the lat¬ ter end of July and the beginning of Auguft ; at which time the plants muft be particularly attended to, and every leaf carefully fearched. As foon as a wound is difcovered, and it will not be long before it is percep¬ tible, care muft be taken to deftroy the caufe of it, which will be found near it, and from its unfubftantial texture may eafily be cruftted : but the beft method is to pull it away by the horn, and then crufli it. When the tobacco is fit for being gathered, as will appear from an attention to the foregoing dire£tions, •on the firft morning that promifes a fair day, before the fun is rifen, take an axe or a long knife, and holding the ftalk near the top with one hand, fever it from its root with the other, as low as poflible. Lay it gently on the ground, taking care not to break off the leaves, and there let it remain expofed to the rays of the fun throughout the day, or until the leaves, accord¬ ing to the American expreflion, are entirely wilted: that is, till they become limber, and will bend any way without breaking. But if the weather ftiould prove rainy without any intervals of funftiine, and the plants appear to be fully ripe, they muft be houfed immediately. This muft be done, however, with great care, that the leaves, which are in this ftate very brittle, may not be broken. They are next to be placed under proper {belter, either in a barn or covered hovel, where they cannot be affefted by rain or too much air, i ] NIC thinly fcattered on the floor; and if the fun does not appear for feveral days, they muft be left to wilt in that manner 5 but in this cafe the quality of the tobacco will not be quite fo good. 'When the leaves have acquired the above-mentioned flexibility, the plants muft be laid in heaps, or rather in one heap if the quantity is not too great, and in about 24 hours they will be found to fweat. But during this time, when they have lain for a little while, and begin to ferment, it will be neceffary to turn them -, bringing thole which are in the middle to the furface, and placing thofe which are at the furface in the middle. The longer they lie in this fituation, the darker coloured is the tobacco; and this is termed. fweating the tobacco. After they have lain in this manner for three or four days, (for a longer con¬ tinuance might make the plants turn mouldy), they may be fattened together in pairs with cords or wood¬ en pegs, near the bottom of the ftalk, and hung acrofs a pole, with the leaves fufpended in the fame covered place, a proper interval being left between each pair. In about a month the leaves will be thorough ¬ ly dried, and of a proper temperature to be taken down. This ftate may be afcertained by their appear¬ ing of the fame colour with thofe imported from Ame ¬ rica. But this can be done only in wet weather.—The tobacco is exceedingly apt to attradt the humidity oi the atmofphere, which gives it a pliability that is ab- folutely neceffary for its prefervation 5 for if the plants are removed in a very dry ieafon, the external parts of the leaves will crumble into dull, and a confiderable wafte will enfue. Cure.—As foon as the plants are taken down, they muft again be laid in a heap, and preffed with heavy logs of wood for about a week -, but this climate may poflibly require a longer time. While they remain in this ftate, it will be neceffary to introduce your hand frequently into the heap, to difeover whether the heat be not too intenfe; for in large quantities this will fometimes be the cafe, and confiderable damage will be occafioned by it. When they are found to heat too much, that is, when the heat exceeds a moderate glowing warmth, part of the weight by which they are preffed muft be taken array ; and the caufe being removed, the effedt will ceafe. T his is called the fc~ cond or lajl fwcating; and, when completed, which it generally will be about the time juft mentioned, the leaves muft be ftripped from the ftalks for ufe. Many omit this laft fweating 5 but Mr Carver thinks that it takes away any remaining harftmtfs, and renders the to¬ bacco more mellow. The ftrength of the ftalk alfo is diffufed by it through the leaves, and the whole mafs be¬ comes equally meliorated.—Vv hen the leaves are ftrip¬ ped from the ftalks, they are to be tied up in bunches or hands, and kept in a cellar or other damp place j though if not handled in dry weather but only during a rainy feafon, it is of little eonfequence in what part of the houfe or bar n they are laid up. At this period the tobacco is thoroughly cured, and as proper for manu- fadturing as that imported from the colonies. Our author advifes the tobacco planter, in his firft trials, not to be too avaricious, but to top his plants before they have gained their utmoft height : leaving only about the middle quantity of leaves directed before to give it a tolerable degree of ftrength. For though B 2 this, Nicotians. NIC [i ana- this, if eXceflive, might be abated during the cure by an increafe of Iweating, or be remedied the next feafon by fuifering more leaves to grow, it can never be added ; and, without a certain degree of ftrength, the tobacco will always be taftelefs and of little value. On the contrary, though it be ever fo much weakened by fweating, and thereby rendered mild, yet it will never lofe the aromatic flavour, which accompanied that ftrength, and which greatly adds to its value. A fquare yard of land, he tells us, will rear about 500 plants, and allow proper fpaCe for their nurture till they are fit for tranfplanting. The following extract, which is copied from a ma- nufcript of Dr Barham (a), for directing the raifing, cultivating, and curing tobacco in Jamaica, is perhaps worthy of the attention of thofe who wifh to be further acquainted with this fubjelU. “ Let the ground or woodland wherein you intend planting tobacco be well burned, as the greater the quantity of wood allies the better. The fpot you in¬ tend raifing your plants on mull be well Brewed with allies, laid fmooth and light : then blow the feed from the palm of your hand gently on the bed, and cover it over with palm or plantain leaves. “ When your plants are about four inches high, draw them and plant them out about three feet afun- der ; and when they become as high as your knee, cut or pluck off the top ; and if there are more than 12 leaves on the plant, take off the overplus, and leave the reft entire. “ The plant fhould now be daily attended to, in or¬ der to deftroy the caterpillars that are liable to infeft it; as alfo to take off every fprout or fucker that puts out at the joints, in order to throw the whole vegetable nourilh- ment into the large leaves. “ When the edges and points of the leaves begin to turn a little yellow, cut down the ftalks about ten o’clock in the morning, taking the opportunity of a fine day, and be careful the dew is fully off the plant, and do not continue this work after two in the after¬ noon. As faft as it is cut let it be carried into your tobacco houfe, which muft be fo clofe as to fliut out all air, (on this much depends), and hung up on lines tied acrofs, for the purpofe of drying. “ When the ftalks begin to turn brownifti, take them off the lines, and put them in a large binn, and lay on them heavy weights for 12 days ; then take them out, and ftrip off the leaves, and put them again into the binn, and let them be well preffed, and fo as no air gains admiftion for a month. Take them out ; tie them in bundles about 60 leaves in each, which are called monocoes ; and are ready for fale. But obferve to let them always be kept clofe till you have occaficn to difpofe of them. “ Let your curing houfe be well built, and very elofe and warm 5 if a boarded building, it will not be amifs, in a wet fituation, to cover the whole outfide with thatch and plantain tralh, to keep off the damps; for by this care you preferve the fine volatile oil in the 2 ] NIC leaves. Obferve, no frnoke is to be made ufe of or ad- Nicctiana, mitted into your curing houfe.” Nictitating For an account of the medical effects of tobacco, fee [t]embrane» Materia Medica Index. ’ v ^ The moft common ufes of this plant, are either as a fternutatory when taken by way of fnuff, as a maftiea- tory by chewing it in the mouth, or as effluvia by fmok- ing it; and when taken in moderation, it is not an un¬ healthful amufement. Before pipes were invented, it ■was ulually fmoked in fegars, and they are ffill in ufe among fome of the fouthern nations. The method of preparing thefe is at once fimple and expeditious. A leaf of tobacco being formed into a fmall twifted roll, fomewhat larger than the Item of a pipe, and about eight inches long, the fmoke is conveyed through the winding folds which prevent it from expanding, as through a tube j fo that one end of it being lighted, and the other applied to the mouth, it is in this form ufed without much inconvenience. But, in procefs of time, pipes being invented, they were found more com¬ modious vehicles for the fmoke, and are now in general ufe. Among all the produftions of foreign climes intro¬ duced into thefe kingdoms, fcarce any has been held in higher eftimation by perfons of every rank than to¬ bacco. In the countries of which it is a native, it is confidered by the Indians as the moft valuable offer¬ ing that can be made to the beings they worftiip. They ufe it in all their civil and religious ceremonies. When once the fpiral wreaths of its imoke afcend from the feathered pipe of peace, the compaft that has been juft made is confidered as facred and inviolable. Like- wife, when they addrefs their great Father, or his guar¬ dian fpirits, refiding, as they believe, in every extraor¬ dinary produ&ion of nature, they make liberal offerings to them of this valuable plant, not doubting but that they are thus fecured of prote&ion. Tobacco is made up into rolls by the inhabitants of the interior parts of America, by means of a machine called a tobacco wheel. With this machine they fpin the leaves after they are cured, into a twift of any fize they think fit; and having folded it into rolls of about 20 pounds each, they lay it by for ufe. In this ftate it will keep for feveral years, and be continually im¬ proving, as it always grows milder. The Illinois ufual- ly form it into carrots ; which is done by laying a num¬ ber of leaves, when cured, on each other after the ribs have been taken out, and rolling them round with pack¬ thread, till they become cemented together. Thefe rolls commonly meafure about 18 or 20 inches in length, and nine round in the middle part. Tobacco forms a very confiderable article in com¬ merce *, for an account of which, fee the articles Glas¬ gow and Virginia. NICTITATING membrane, a thin membrane chiefly found in the bird and fifh kind, which covers the eyes of thefe animals, fheltering them from the duff or too much light; yet is fo thin and pellucid, that they can fee pretty well through it. NIDDUI, (a) This gentleman was cotemporary with Sir Hans Sloane. He was a man of great probity, an able phyfi- cian, and a Ikilful naturalift. He collefled and arranged a number of the plants of Jamaica, which he prefented to Dr Sloane, and made feveral communications to the Royal Society. N I E f 13 IIMui NIDDUI, in the Jewifh cuftoms, is ufed to (ignify II “ feparated or excommunicated.” I his, according to Niefter- . jfome, ’tvas to be underftood of tlie leffer fort of excom¬ munication in ufe among the Hebrews. He that had incurred it was to withdraw himfelf from his relations, at leaft to the diflance of four cubits : it commonly- continued a month. If it was not taken oft in that time, it might be prolonged for 60 or even 90 days : but if, within this term, the excommunicated perfon did not give fatisfacfion, he fell into the cherem, which was a fecond fort of excommunication and thence into the third fort, called fhammnta or Jhematta, the moil terrible of all. But Selden lias proved that there were only two kinds of excommunication, viz. the great¬ er and lefs 5 and that thefe three terms were ufed indif¬ ferently. NIDUS, among naturalifts, fignifies a neft or proper repoiitory for the eggs of birds, infefts, &c. where the •young of thefe animals are hatched and nurfed. NIDIFICATION, a term generally applied to the formation of a bird’s neft, and its hatching or bring¬ ing forth its young. See Ornithology. NIECE, a brother’s or filler’s daughter, which in the civil law is reckoned the third degree of confan- guinity. NIEMEN, a large river of Poland, which rifes in Lithuania, where it pafles by Bielica, Grodno, and Konno : it afterwards runs through part of Samogitia and Ducal Pruflia, where it falis into the lake called the Cwifch-haff, by feveral mouths, of which the moll northern is called the Rufs, being the name of a town it pafles by. NIENBURGH, a rich and ftrong town of Germany, in the duchy of Brunfwic-Lunenburg, with a ftrong caftle. It carries on a confiderable trade in corn and wool, and is feated in a fertile foil on the river Wefer. E. Long. 9. 26. N. Lat. 52. 44. NIEPER, or Dnieper, a large river of Europe, and one of the moll eonfiderable of the north, formerly call¬ ed the Borifthenes. Its fource is in the middle of Muf- covy, running weft by Smolenlko, as far as Orfa ; and then turns fouth, palling by Mohilow, Bohaezo, Kiow, Czyrkafly, the fort re fs of Kudak, Deflau, and Oczakow, falling into the Black fea j as alfo in its courfe it divides Little Tartary from Budziac Tartary. NIESS, a mountain in the environs of Berne in Switzerland. It is the laft mountain in a high chain of calcareous hills, of which the Stockhorn, the Neuneren, and the Ganterifh, have been illuftrated by the botanical labours of the celebrated Haller. Niefs Hands on the borders of the lake Thun, and feparates the valley of Frutingen from that of Simme. It is very interefting to the curious traveller, on account of the fine view from its top ; and to naturalifts, becaufe it joins the Alps. Towards its foot, beds of Hate have been difeovered 5 it is of calcareous Hone higher up *, and near its top is found a fpecies of pudding- ftone, filled with fmall fragments of broken petrifac¬ tions. NIESTER, a large river of Poland, which has its fource in the lake Niefter, in the palatinate of Lem- burg, where it pafles by Halicz. Then it feparates Podolia and Oczakow Tartary from Moldavia and Budziac Tartary j and falls into the Black La at 4- ] NIG Belgorod, between the mouths of the Nieper and the Niefter Danube. H NIGEL LA, Fennel-flower, or Devil in a Bujl,, ^ ^ ^ a genus of plants, belonging to the pentandria clafs. See Botany Index. NIGER, C. Pescennius Justus, a celebrated gover¬ nor in Syria, well known by his valour in the Roman armies while in a private ftation. At the death of Per- tinax he was declared emperor of Rome; and his claims to that elevated ftation were fuppoited by a found underftanding, prudence of mind, moderation, courage, and virtue. He propofed to imitate the aftions of the venerable Antoninus, of Trajan, of Titus, and M. Au¬ relius. He was remarkable for his fondnefs of ancient difeipline. He never fuffered bis foldiers to drink wine, but obliged them when thirfty to ufe water and vinegar. He forbade the ufe of filver or gold utenfils in his camp. All the bakers and cooks were driven away, and the foldiers were ordered to live during the expedition they undertook merely upon bifeuits. In his puniftiments Niger was inexorable : be condemned ten of his foldiers to be beheaded in the prefence cf the army becaufe they had ftolen and eaten a fowl. The fentence was heard with groans. The army interfered; and when Niger confented to diminifh the punilhment, for fear cf kindling rebellion, he yet ordered the criminals to make each a reftoration of ten fowls to the perfon whofe pro¬ perty they had ftolen. They were befides ordered not to light a fire the reft of the campaign, but to live upon cold aliments and to drink nothing but water. Such great qualifications in a general feemed to promife the reftoration of ancient diicipline in the Roman armies; but the death of Niger frullrated every hope of reform. Severus, who had alfo been invefted with the imperial purple, marched againft him : fome battles were fought, and Niger was at laft defeated, A. D. 195. His head was cut oft' and fixed to a long fpear, and carried in triumph through the ftreets of Rome. He reigned about a year. Niger, a large river of Africa, of which many er¬ roneous opinions have been entertained. According to Herodotus, Pliny, Ptolemy, and many of the ancients, this river runs from weft to eaft, an opinion which was long forgotten, and in more modern times it was be¬ lieved to flow from eaft to weft ; but from the recent difeoveries of the indefatigable Mr Park, who himfelf faw this majeftic river, the opinion of the ancients is now fully eitabliftied, that its courfe is from weft to eaft. The fource of the Niger is fuppofed to be in that mountainous region in weftern Africa, which gives origin to the rivers Gambia and Senegal, which dii- charge their waters into the Weftern ocean, while the Niger vifing from the oppofite fide of the mountains, takes an eafterly direction. See Africa, p. 264. and 272. The Niger is called Joliba by the natives. NIGHT, that part of the natural day during which the fun is underneath the horizon; or that fpace where¬ in it is dulky. Night was originally divided by the Hebrews and other eaftern nations into three parts or watches. The Romans, and after them the Jews, divided the night into four parts or watches ; the firft of which be¬ gan at funfet, and lafted till nine at night, according to our way of reckoning; the fecond lafted till mid¬ night ; NIG [i J'fight night; the third till three in the morning ; and the ^ fourth ended at funrife. The ancient Gauls and Ger- TVatchinjr. mans divided their time not by days but by nights ; and w—the people of Iceland and the Arabs do the fame at this day. The like is obferved of the Anglo-Saxons.—The length and fhortnefs of night or of darknefs is according to the feafon of the year and portion of the place ; and the caufes of this variety are now well known. See Astronomy, &c. Night, in fcripture language, is ufed for the times of heathenifh ignorance and profanenefs (Rom. xiii. 12.) ; for adverlity and affliction (If. xxi. 12.) ; and laflly, for death (John ix. 4.). Night-Angling, a method of catching large and fhy fi(h in the night-time. Trout, and many other of the better forts of fflli, are naturally fhy and fearful ; they therefore prey in the night as the fecureft time.—The method of taking them on this plan is as follows : The tackle mud be ftrong, and need not be fo fine as for day fifhing, when every thing is feen ; the hook mud be baited with a large earth worm, or a black fnail, and thrown out into the river •, there mud be no lead to the line, fo that the bait may not fink, but be kept drawling along, upon or near the furface. What¬ ever trout is near the place will be brought thither by the motion of the water, and will feize the worm or fnail. The angler will be alarmed by the noife which the fidi makes in riling, and mud give him line, and time to fwallow the hook ; then a flight touch fecures him. The bed and larged trouts are found to bite thus in the night 5 and they rife modly in the dill and clear deeps, not in the fwift and fhallow currents. Some¬ times, though there are fifh about the place, they will not rife at the bait : in this cafe the angler mud put on fome lead to his line, and fink it to the bottom. Night-Mare, or Incubus. See Medicine, N° 329. Night-Walkers. See Medicine, N° 329, and Noc- ' TAMBULI. Night- Walkers, in Lavo, are fuch perfons as deep by day and walk by night, being oftentimes pilferers or didurbers of the public peace. Condables are authori¬ zed by the common law to arred night-walkers and fu- fpicious perfons, &c. Watchmen may alfo arred night- walkers, and hold them until the morning: and it is faid, that a private perfon may arred any fufpicious night-walker, and detain him till he give a good ac¬ count of himfelf. One may be bound to the good be¬ haviour for being a night-walker j and common night- walkers, or haunters of bawdy-houfes, are to be indict¬ ed before judices of peace, &c. But it is not held law¬ ful for a condable, &c. to take up any woman as a night-walker on bare fufpicion only of being of ill fame, unlefs die be guilty of a breach of the peace, or fome unlawful act, and ought to be found mifdoing. NIGHTINGALE, afpeciesof motacilla. See Or¬ nithology Index. NIGHTSH /VDE. See Solanum, Botany Index. Deadly NIGHTSHADE. See Atropa, Botany In¬ dex.—The berries of this plant are of a malignant poi- fonous nature; and, being of a fweet tade, have fre¬ quently proved dedruCtive to children. It is faid, that a large glafs of warm vinegar, taken as foon as pofli- ble after eating the berries, will prevent their bad ef¬ fects. NlGBT-Watching, a praCtice of very remote antiquity, 4 ] NIG which belongs to the olded regulations of police. So Night- early a,s the time of Solomon we find mention made of ^Vatching. it, and likewife in the Pfalms of David *. Sentinels were dationed in different places in Athens and other Solomon] cities of Greece, and they were kept to their duty by chap. iii. the vifitations of the Thefmothetce. There were alfo ver- 3; p/T- triumviri noBurni in the city of Rome, as appears from i XaVU- i* the commentaries of Heubach on the police of the Ro¬ mans. It appears, however, that the defign of thefe inditutions was rather the prevention of fires, than the guarding againd alarms or dangers by night, although attention was likewife paid to thefe in procefs of time.. The apprehenfion of fires was the pretext of Augudus, when he widied to drengthen the night-watch for fup- preffing noCiurnal commotions. It does not appear that calling out the hours became an edablitlied praCtice before the ereCtion of city gates, and probably had its rife in Germany j yet it would have been attended with advantages in ancient Rome, where there were no public clocks, nor any thing in private houfes to indicate the hours. The periods for foldiers to mount guard were determined by water- clocks ; at the end of each hour they blew a horn, and by means of this fignal each individual might afeertain the hour of the night. It feems evident, however, that thefe regulations were only attended to in time of war. In the city of Paris, night-watching was edabliflied, as at Rome, in the very commencement of its monarchy5 and De la Mare quotes the ordinances of Clothaire II. upon this fubjeCt, in the year 595. The citizens at firli kept watch in rotation 5 but this practice was after¬ wards fet afide, and, by the payment of a certain fum of money, a permanent watch was edablidied. In the opinion of the learned and indefatigable Beckmann, the eftablifhment of fingle watchmen, to call out the hours through the ftreets, is peculiar to Germany, and only copied by furrounding nations in more modern times. The elector, John George, in 1588, appointed watch¬ men at Berlin ; and Mabillon deferibes it as a practice peculiar to that country. Horns are made ufe of by watchmen in fome places, and rattles in others, the for¬ mer being moft proper for villages, and the latter for cities. The Chinefe, fo early as the ninth century, had Avatchmen ported on their towers, who announced the hours both by day and night, by ftriking forcibly on a fufpended board, which in that country is faid to be in ufe to the prefent period ; and at Peterfburgh, in Ruf- fia, the watchmen employ a fufpended plate of iron for a fimilar purpofe. In this manner alfo Chriftians are affembled together in the Levant, for the purpofe of at¬ tending divine fervice; and monks were thus awakened in monalteries at the moft early periods, to attend to the proper hours of prayer. We find mention made of fteeple-watchmen in Ger¬ many in the 14th century. In the year 1563, a church- fteeple was erected in Leifnig, and an apartment built in it for a permanent watchman, who was obliged to proclaim the hours every time the clock ftruck. Per¬ manent watchmen were kept in many of the fteeples at Ulm in the 15th century. The fame thing was prac- tifed at Frankfort on the Mayne, at Oettingen, and many other places j and Montaigne was aftonifhed at finding a man on the fteeple of Conftance, who kept watch Night- Watching Nile NIL '[ 15 ] NIL watch upon it continually, and avIio on no pretext -what¬ ever was permitted to come down. Becbnami's Hijl. of Inventions, iii. 425. NIGIDiUS Figulus, Publius, one of the molt learned men of ancient Rome, flouriflied at the fame time with Cicero. He wrote on various fubjects •, but his pieces appeared fo refined and difficult that they were not regarded. He affifled Cicero, with great prudence, in defeating Catiline’s confpiracy, and did him many fervices in the time of his adverfity. He adhered to Pompey in oppofition to Ciefar j which oc- cafioned his exile, he dying in baniffiment. Cicero, who had always entertained the higheft efteem for him, wrote a beautiful confolatory letter to him (the 13th of lib. iv. ad Familiares'). NIGRINA, a genus of plants belongingto the pent- andria clafs. See Botany Index. NIGRINE, an ore of titanium. See Mineralogy Index. NIGRITIA. See Negroland. NIGUA. See Chegoe. NILE, a large and celebrated river of Africa, to which the country of Egypt owes its fertility ; and the exploring the fources of which, has from the remoteft ages, been accounted an impracticable undertaking. This problem has been folved by James Bruce, Efq. of Kinnaird, in Scotland \ who fpent feveral years at the court of Abyffinia, and by the favour of the emperor and great people of the country was enabled to aecom- pliffi the arduous talk. In the account of his travels, this gentleman has been at particular pains to ffiow, that none of thole who under¬ took this talk ever fucceeded in it but himfelf. The in¬ quiry concerning its fprings, he fays, began either be¬ fore hiftory or tradition, and is by fome fuppofed to be the origin of hieroglyphics. Though Egypt was the country which received the greatelt benefit from this river, it was not there that the inquiries concerning its inundation began : it being probable that every thing relative to the extent and periodical time of that inunda¬ tion would be accurately fettled (which could not be done but by a long feries of obfurvations) before any perfon would venture to build houfes within its reach. The philofophers of Meroe, in our author’s opinion, were the firft who undertook to make a number of ob- lervations fufficient to determine thefe points \ their country being fo fituated, that they could perceive every thing relative to the increafe or decreafe of the river without any danger from its overfiorving. Being much addicted to afironomy, it could not long efcape them, that the heliacal riling of the dog-ftar, was a fignal for Egypt to prepare for the inundation ; without which it was vain to expeft any crop. The connexion of this celeltial fign with the annual riling of the river would undoubtedly foon become a matter of curiolity ; and as this could not eafily be difcovered, it was natural for an ignorant and fuperifitious people to afcribe the whole to the action of the dog liar as a deity. Still, hovcever, by thofe who were more enlightened, the phenomenon would be afcribed to natural caufes •, and a great Hep towards the difcovery of thefe, undoubtedly was that of the fources of the river itfelf. In the early ages, when travelling into foreign countries was impradlicable by private perfons, the inquiry into the fources of the Nile became an object to the greatefi: monarchs. Sefoltris is faid to have preferred the honour of difcovering them almoft to all the victories he obtained. Alexander the Great is Avell known to have had a great curiofity to difeover thefe fountains. On his arrival at the temple of Jupiter Ammon, he is faid to have made inquiry con¬ cerning the fountains of the Nile, even before he alked about his own defeent from Jupiter, 'ihe prielts are faid to have given him proper directions for finding them : and Alexander took the molt ready means of accomplilhing his purpofe, by employing natives of Ethiopia to make the fearch. Thefe difeoverers, in the opinion of Mr Bruce, miffed their aim, by reafon of the turn which the Nile takes to the call in the latitude of 90 where it begins to furround the kingdom of Go- jam 5 but which they might imagine to be only a wind¬ ing of the river foon to be compenlated by an equal turn to the weft. “ They therefore (fays he) continued their journey fouth till near the line, and never faw it. more j as they could have no poffible notion it had turned back behind them, and that they had left it as far north as latitude 9°. They reported then to Alex¬ ander, what -was truth, that they had afeended the Nile, as far fouth as latitude 90 ; where it unexpectedly took its courfe to the eaft, and was feen no more. The river Avas not knoAvn, nor to be heard of near the line, or farther fouth ward, nor Avas it diminiffied in fize, nor had it given any fymptom that they Avere near its fource; they had found the Nile calentem (warm), Avhile they expefted its rife among melting fnows. Mr Bruce is of opinion that this turn of the Nile to the eaftAvard Avas the occafion of Alexander’s ex¬ travagant naiftake, in fuppofing that he had difcovered the fountains of the Nile Avhen he Avas near the fonree of the Indus ; and Avhich he Avrote to his mother, though he aftertvards caufed it to be erafed from his books. Ptolemy Philadelphus fucceeded Alexander in his attempts to difeover the fource of the Nile 5 but he like- AA'ife proving unfuccefsful, the talk Avas next undertaken by Ptolemy Euergetes, the moft poA\:erful of the Greek princes Avho fat on the throne of Egypt. “ In this (fays Mr Bruce) he had probably fucceeded, had he not miftaken the river itfelf. Pie fuppofed the Shis, noAV the Tacazze, to be the Nile ; and afeending in the direction of its ftream, he came to Axum, the capital of Sire and of Ethiopia. But the ftory he tells of the fnoAV Avhich he found knee-deep on the mountains of Samen, makes me queftion whether he ever crofted the Shis, or was himfelf an ocular Avitnefs of Avhat he fays he obferved there.” Cmfar had the fame curiofity Avith other conquerors to vifit the fprings of the Nile, though his fituation did not alloAV him to make any attempt for that purpofe. Nero, hoAvever, Avas more ailive. He fent tAVo centu¬ rions into Ethiopia, with orders to explore the unknoAvn fountains of this river *, but they returned Avithout ha¬ ving accompliffied their errand. They reported, that, after having gone a long Avay, they came to a king of Ethiopia, who furniffied them with neceffaries, and re¬ commendations to fome other kingdoms adjacent; pai- fing Avhich, they came to immenfe lakes, of Avhich no¬ body knerv the. end, nor could they ever hope to find it. Their ftory, hoAVover, is by Mr Bruce fuppofed to be a fiftion y 5 NIL [ i ^e- fidtion 5 as tlie Nile forms no lakes throughout its courfe, v excepting that of Tzana or Dembea, the limits of which are eafily perceived. No other attempt was made by the ancients to difco- ver the fources of this celebrated river j and the matter was looked upon to be an impoffibility, infomuch that caput NM queerer? became a proverb, denoting the im¬ poffibility of any undertaking. The firft who, in more modern ages, made any attempt of this kind, was a monk fent into Abyffinia in the year 522, by Nonnofus, am- baffador from the emperor Juft in. This monk is called Cofmas the Hermit, and likewife IndojJarJles, from his fuppofed travels into India. He proceeded as far as the city of Axum, but did not vifit that part of the coun¬ try where the head of the Nile lies ; nor, in Mr Bruce’s opinion, wrould it have been practicable for him to do fo. The difeovery, however, is faid to have been made at laft by Peter Paez the miffionary. But the truth of this account is denied by Mr Bruce, for the following reafons : 1. “ No relation of this kind (fays he) was to be found in three copies of Peter Paez’s hiftory, to which I had accefs when in Italy, on my return home. One of thefe copies I faw at Milan *, and, by the intereft of friends, had an opportunity of peruling it at my leifure. The other two were at Bologna and Rome. I ran through them rapidly j attending only to the place where the defeription ought to have been, and where I did not find it: but having copied the firft and laft; page of the Milan manufeript, and comparing them with the two laft mentioned, I found that all the three were word for word, the fame, and none of them con¬ tained one fyllable of tire difeovery of the fource. 2. Alphonfo Mendez came into Abyffinia about a year af¬ ter Paez’s death. New and defirable as that difeovery muft have been to himfelf, to the pope, king of Spain, and all his great patrons in Portugal and Italy *, though he wrote the hiftory of the country, and of the parti¬ culars concerning the miffion in great detail and with good judgment, yet he never mentions this journey of Peter Paez, though it probably muft have been convey¬ ed to Rome and Portugal after his infpedftion and under his authority. 3. Balthazar Tellez, a learned Jefuit, has wrote two volumes in folio, with great candour and impartiality, confidering the fpirit of thofe times ; and he declares his work to be compiled from thofe of Al-' phonfo Mendez the patriarch, from the two volumes of Peter Paez, as well as from the regular reports made by the individuals of the company in feme places, and by the provincial letters in others j to all which he had complete accefs, as alfo to the annual reports of Peter Paez, among the reft from 1598 to 1622 ; yet Tellez makes no mention of fuch a difeovery, though he is very particular as to the merit of each miffionary during the long reign of Facilidas, which occupies more than half the two volumes.” The firft, and indeed the only account of the foun¬ tains of the Nile, publifhed before that of Mr Bruce, was Kircher’s j who fays that he took it from the writ¬ ings of Peter Paez. The time when the difeovery is faid to have been made V'as the 21ft of April 1618; at which feafon the rains are begun, and therefore very un- wholefome ; fo that the Abyffinian armies are not with¬ out extreme neceffity in the field \ between September and February at fartheft is the time they are abroad from the capital and in a&ion. 6 ] NIL “ The river (fays Kircher) at this day, by the Ethio- Nile, plans, is called Abavy ; it riles in the kingdom of Go- 1 jam, in a territory called Saba/a, whofe inhabitants are called A/goxvs. The fource of the Nile is fituated in the weft part of Gojam, in the higheft part of a valley, which refembles a great plain on every fide furrounded by high mountains. On the 21ft of April 1618, being here, together with the king and his army, I afeended the place, and obferved every thing with great atten¬ tion : I difeovered firft two round fountains each about four palms in diameter, and faw, with the greateft delight, what neither Cyrus the Perfian, nor Cambyfes, nor Alexander the Great, nor the famous Julius Caefar, could ever difeover. The two openings of thefe foun¬ tains have no iiTue in the plain on the top of the moun¬ tain, but How from the root of it. The fecond fountain lies about a ftone-caft weft from the former : the inhabit tants fay that this whole mountain is full of water j and add, that the whole plain about the fountain is floating and unfteady, a certain mark that there is wrater con¬ cealed under it ; for Avliich reafon the water does not overflow at the fountain, but forces itfelf with great violence out at the foot of the mountain. The inhabi¬ tants together with the emperor, who was then prefent •with his army, maintain, that that year it trembled very little on account of the drought ; but in other years, that it trembled and overflowed fo that it could fcarce be approached without danger. The breadth of the circumference may be about the call of a fling : be¬ low the top of this mountain the people live about a league diftant from the fountain to the weft ; and this place is called Geefh; and the fountain feems to be about a cannon-lhot diftant from Geefh ; moreover the field w here the fountain is, is on all fides difficult of ac¬ cefs, except on the north fide, where it may be afeended with eafe.” On this relation Mr Bruce obferves, that there is no fuch place as Saba/a ; it ought to have been named Sa~ cala, fignifying the highell ridge of land, where the wa¬ ter falls equally down on both fides, from eaft and weft, or from north and fouth. So the ffiarp roofs of our houfes, where the water runs down equally on the op- pofite fides, are called by the fame name. Other objec¬ tions are drawn from the fituation of places, and from the number and fituation of the fountains themfelves, every one of which Mr Bruce found by adlual menfu- ration to be different from Kircher’s account. The fol¬ lowing, however, he looks upon to be decifive that Paez never was on the fpot. He fays, “ the field in which the fountains of the Nile are, is of very difficult accefs ; the afeent to it being very fteep, excepting on the north, where it is plain and ealy. Now, if we look at the be¬ ginning of this defeription, we fhould think it would bo the defeent, not the afeent, that would be troublefome j for the fountains wrere placed in a valley, and people ra¬ ther defeend into valleys than afeend into them ; but fuppofing it was a valley in which there was a field up¬ on which there was a mountain, and on the mountain thefe fountains; ftill, I fay, that thefe mountains arc nearly inacceffible on the three fides; but that the moffi difficult of them all is the north, the way we afeend from the plain of Goutto. From the eaft, by Sacala, the afeent is made from the valley of Litchambara, and from the plain of Affoa to the fouth you have the al- moft perpendicular craggy cliff of Geefh, covered with thorny NIL [ i? ] NIL thorny bufhes, trees, and bamboos, which cover the mouths of the caverns •, and on the north you have the mountains of Aformafka, thick fet with all forts of thorny trees and flmibs, efpecially with the kantuffa : thefe thickets are, moreover, filled with wild beafls, ef¬ pecially huge, long-haired baboons, which we frequent¬ ly met walking upright. Through thefe high and dit- ficult mountains we have only narrow paths, like thofe of (keep, made by the goats, or the wild beads we are fpeaking of, which, after we had walked on them for a long fpace, landed us frequently at the edge of fome valley or precipice, and forced us to go back again to feek a new road. From towards Zeegam to the welt- ward, and from the plain where the river winds fo much, is the only eafy accefs to the fountains of the Nile. : and they that afcend to them by this w^ay will not even think that approach too eafy.” Peter Heiling, a Proteftant of Lubec, refided feveral years in the country of Gojam, and wras even governor of it, but he never made any attempt to difcover the fource of the Nile ; dedicating himfelf entirely to a ftu- dious and folitary life. The moft extraordinary at¬ tempt, however, that ever was made to difcover the fource of this or any other river, was that of a German nobleman named Peter Jofcph de Roux, comte de Defre- val. He had been in the Danilh navy from the year 1721 j and, in 1739, was made rear-admiral. That fame year he refigned his commiflion, and began his at¬ tempt to difcover the fource of the Nile in Egypt. To this country he took his wife along with him ; and had no fooner reached Cairo, than he quarrelled with a Tur- kifh mob on a point of etiquette •, which inftantly brought upon them the janizaries and guards of police, to take thetn into cuftody. The countefs exerted her- felf in an extraordinary manner ; and armed only with a pair of fcilfars, put all the janizaries to flight, and even wounded feveral of them ; fo that her hulband was left at liberty to purfue his plan of difcevery. To ac- complith this, he provided a barge with fmall cannon, and furnifhed with all neceflary provifions for himfelf and his wife, who was ftill to accompany him. Before he fet out, however, it was fuggefted to him, that, fup- pofing government might proteft him fo far as to allow his barge to pafs the confines of Egypt fafely, and to the firft cataraft ; fuppofing alfo that (he was arrived at Ibrim, or Deir, the laft garrifons depending on Cairo ; yet ftill fome days journey above the garrifons of Deir and Ibrim began the dreadful deferts of Nubia •, and farther fouth, at the great cataradl of Tan Adel, the "Nile falls 20 feet down a perpendicular rock—fo that here his voyage muft undoubtedly end. The count, however, flattered himfelf with being able to obtain fuch afliftance from the garrifons of Ibrim and Deir as would enable him to take the veflel to pieces, and to carry it above the cataradf, where it could again be launched in¬ to the river. To facilitate this fcheme he had even en¬ tered into a treaty with fome of the barbarians named Kennoufs, who refide near the cataraft, and employ themfelves in gathering fena, which abounds in their country. Thefe promifed to aflift him in this ex¬ traordinary adventure •, but, luckily for the count, he fuflfered himfelf at laft to be perfuaded by fome Venetian merchants at Cairo not to proceed in perfon on fuch a dangerous and unheard-of navigation, but rather to de¬ pute Mr Norden, his lieutenant, who was likewife to Vol. XV. Part I. ferve as his draughtfman, to reconnoitre the forts of Nile. Ibrim and Deir, as well as the cataraft of Jan Adel, ”-y““ and renew his treaty with the Kennoufs. This gentle¬ man accordingly embarked upon one of the veffels com¬ mon on the Nile, but met with a great many difficulties and difafters before he could reach Syene and the firft cataraff •, after which having with ftill greater difficulty reached Ibrim, inftead of meeting with any encourage¬ ment for the count to proceed on his voyage, he was robbed of ail he had by the governor of the fort, and narrowly efcaped with his life \ it having been for fome time determined by him and his foldiers that Mr Nor¬ den ftiould be put to death. By thefe difficulties the count was fo much dilheartened, that he determined to make no more attempts on the Nubian fide. He now refolved to enter Abyfiinia by the itland of Mafuah. With this view he undertook a voyage round the Cape of Good Hope, in order to reach the Red fea by the ftraits of Babelmandel: but having begun to ufe his Spanilh commiffion, and taken two Englilh (hips, he was met by Commodore Barnet, who made prizes of all the veflels he had with him, and fent home the count him¬ felf palfenger in a Portuguefe ftiip to Lilhon. Thus Mr Bruce confiders himfelf as the firft Euro- ropean who reached the fources of this river. He in¬ forms us that they are in the country of the Agows, as Kircher had faid ; fo that the latter muft either have vilited them himfelf, or have had very good information concerning them. The name of the place through which is the paflage to the territory of the Agows, is Abala ; a plain or rather valley, generally about half a mile, and never exceeding a whole mile, in breadth. The mountains which furround it are at firft of an in- confiderable height, covered to the very top with herb¬ age and acacia trees ; but as they proceed to the fouth- ward they become more rugged and woody.—On the top of thefe mountains are delightful plains producing excellent pafture. Thofe to the Aveft join a mountain called Aformafka, where, from a direftion nearly fouth- eaft, they turn fouth, and enclofe the villages and terri¬ tory of Sacala, which lie at the foot of them •, and ftill lower, that is, more to the weftward, is the fmall village of Geeffi,* where the fountains of the Nile are fituated. Here the mountains are in the form of a crefcent ; and along thefe the river takes its courfe. Thofe which en¬ clofe the eaft fide of the plain run parallel to the former in their whole courfe, making part of the mountains of Lechtambara, or at leaft joining with them, and thefe two, when behind Aformalka, turn to the fouth, and then to the fouth-weft, taking the fame form as they do j only making a greater curve, and enclofing them like¬ wife in the form of a crefcent, the. extremity of which terminates immediately above a fmall lake named Goo- deroo in the plain of Affba, below Geelh, and diredlly at the fountains of the Nile. Having palled feveral confiderable ftreams, all of which empty themfelves into the Nile, our traveller found himfelf at laft obliged to afcend a very fteep and rugged mountain, where no other path was to be found but a very narrow one made by the fheep or goats, and which in fome places was broken, and full of holes ; in others, he was obftrufled with large ftones, which feem- ed to have remained there fince the creation. The whole was covered with thick wood ; and he was every¬ where flopped by the kantuffa, as well as by feveral other G thorny NIL [ *8 ] NIL thorny plants almoft as troublefome as that. Having at laft, however, reached the top, he had a fight of the Nile immediately below him 5 butfo diminilhed in fize, that it now appeared only a brook fcarcely fufficient to turn a mill. The village of Geefh is not within fight of the fountains of the river, though not more than 600 yards diftant from them. The country about that place terminates in a cliff of about 300 yards high, which reaches down to the plain of Affoa, continuing in the fame degree of elevation till it meets the Nile again about 17 miles to the fouthward, after having made the circuit of the provinces of Gojam and Damot. In the middle of this cliff is a valt cave running ftraight north¬ ward, with many bye-paths forming a natural labyrinth, of fufficient bignefs to contain the inhabitants of the whole village with their cattle. Into this Mr Bruce advanced about 100 yards; but he did not choofe to go farther, as the candle he carried with him feemed ready to go out; and the people affured him that there -was nothing remarkable to be feen at the end. The face of this cliff, fronting the fouth, affords a very piclurefque view from the plain of Affoa below; parts of the houfes appearing at every ffage through the bullies and thick¬ ets of trees. The mouths of the cavern above mention¬ ed, as well as of feveral others which Mr Bruce did not fee, are hid by almoff impenetrable fences of the worft kind of thorn; nor is there any other communication betwixt the upper part and the houfes but by narrow winding (beep paths, very difficult to be difcovered ; all of them being allowed to be overgrown, as a part of the natural defence of the people. The edge of the cliff is covered with lofty and high trees, which feem to forma natural fence to prevent people from falling down; and the beauty of the flowers which the Abyffinian thorns bear, feems to make fome amends for their bad qualities. From the edge of the cliff of Geelh, above where the village is fituated, the ground dopes with a defcent due north, till we come to a triangular marfh upwards of 86 yards broad, and 286 from the edge of the cliff, and from a prieft’s houfe where Bruce refided. On the eaft, the ground defcends with a very gentle flope from the large village of Sacala, which gives its name to the territory, and is about fix miles diftant from the fource, though to appearance not above two. About the middle of this marfh, and not quite 40 yards from the foot of the mountain of Geefh, rifes a circular hil¬ lock about three feet from the furface of the marfti it- felf, though founded apparently much deeper in it. The diameter of this hillock is not quite 12 feet, and it is furrounded by a (hallow trench which colledf's the water, and fends it off to the eaftward. This is firmly built of fod brought from the fides, and kept conftantly in repair by the Agows, who worfliip the river, and per¬ form their religious ceremonies upon this as an altar. In the midft of it is a circular hole, in the formation or enlargement of which the work of art is evidently dif- cernible. It is always kept clear of grafs and aquatic plants, and the water in it is perfectly pure and lim¬ pid, but without any ebullition or motion difcernible on its furface. The mouth is fome parts of an inch lefs than three feet diameter, and at the time our author firft vi- fited it (Nov. 5. 1770), the water flood about two inches from the brim, nor did it either increafe or diminifh du¬ ring all the time of his refidence at Geefh. On putting dowm the fhaft of a lance, he found a very feeble refi- ftence at fix. feet four inches, as if from weak rufhes and grafs ; and, about fix inches deeper, he found his lance had entered into foft earth, but met with no obffrudHon ^ from ftones or gravel; and the fame was confirmed by ufing a heavy plummet, with a line befmeared with foap. —This is the firit fountain of the Nile. The fecond fountain is fituated at about ten feet di¬ ftant from the former, a little to the welt of fouth; and is only 11 inches in diameter, but eight feet three inches deep. The third is about 20 feet SSW from the firft;; the mouth being fomewhat more than two feet in dia¬ meter, and five feet eight inches in depth. Thefe foun¬ tains are made ufe of as altars, and from the foot of each iffues a brifk running rill, which, uniting with the wa¬ ter of the firft trench, goes off at the eaft fide in a ftream which, our author conjectures, would fill a pipe about twro inches diameter. The water of thefe fountains is extremely light and good, and intenfely cold, though expofed to the fcorching heat of the fun, without any fhelter ; there being no trees nearer than the cliff of Geefh. The longitude of the principal fountain was found by Mr Bruce to be 36° 551 30" E. from Green¬ wich. The elevation of the ground, according to his account, muff be very great, as the barometer flood on¬ ly at 22 Englifh inches. “ Neither (fays he) did it vary fenfibly from that height any of the following days I ftaid at Geefh ; and thence I inferred, that at the fources of the Nile I was then more than tivo miles above the level of the fea; a prodigious height, to enjoy a fky perpetually clear, as alfo a hot fun never overcaft for a moment with clouds from rifing to fetting.” In the morning of Nov. 6. the thermometer flood at 440, at noon 96°, and at funfet 46°. It Avas fenfibly cold at night, and Itill more fo about an hour before funrife. The Nile thus formed by the union of ftreams from thefe three fountains, runs eaftward through the marfh for about 30 yards, with very little increafe of its Avater, but ftill diftinClly vifible, till it is met by the graffy brink of the land defcending from Sacala. By this it is turned gradually NE, and then due north; and in the tAvo miles in Avhich it flows in that direction it receives many fmall ftreams from fprings on each fide ; fo that about this diftance from the fountains it becomes a ftream capable of turning a common mill. Our travel¬ ler Avas much taken with the beauty of this fpot. “ The fmall rifing hills about us (fays he) Avere all thick co¬ vered with verdure, efpecially with clover the largeft and fineft I ever farv ; the tops of the heights covered Avith trees of a prodigious fize: the ftream, at the banks of Avhich Ave Avere fitting, was limpid, and pure as the fineft: cryflal ; the fod covered thick Avith a kind of bufhy tree, that feemed to affeCl to grow to no height, but, thick Avith foliage and young branches, rather to affift the furface of the Avater ; Avhilft it bore, in prodi¬ gious quantities, a beautiful yelloAV floAver, not unlike a, Angle rofe of that colour, but without thorns ; and in¬ deed, upon examination, we found that it AAras not a fpe- cies of the rofe, but of the hypericum.” Here Mr Bruce exults greatly in his fuccefs; as hav¬ ing not only feen the fountains of the Nile, but the ri¬ ver itfelf running in a fmall ftream; fo that the ancient faying of the poet, Nec licuit populis parvum te Ni/e videre, could not be applied to him. Here he Jlepped over it, he fays, more than 50 times, though he had told us, in the preceding page, that it was three yards over. From this ford, however, the Nile turns to the weft ward; and, after Nile. N I L Nils, after running over loofe Hones occafionally in that di- --V——-1 region about four miles farther, there is a fmall eata- raft of about fix feet in height j after which it leaves the mountainous country, and takes its courfe through the plains of Goutto. Here it flows fo gently that its motion is fcarcely to be perceived, but turns and winds in its direction more than any river he ever law j form¬ ing more than 20 (harp angular peninfulas in the fpace of five miles. Here the foil is compofed of a marfhy clay, quite deftitute of trees, and very difficult to travel through ; and where its ftream receives no confiderable addition. Iffuing out from thence, however, it is joined by feveral rivulets which fall from the mountains on each fide, fo that it becomes a confiderable ftream, with high and broken banks covered with old timber trees for three miles. In its courfe it inclines to the north- eaft, and winds very much, till it receives firft a fmall river named Diwa, and then another named Dee-ohhn, or the river Dee. Turning then ftiarply to the eaft, it falls down another catara£t, and about three miles be¬ low receives the Jemma, a pure and limpid ftream, not inferior in fize to itfelf. Proceeding ftill to the north¬ ward, it receives a number of other ftreams, and at laft crolfes the fouthern part of the lake Tzana or Dembea, preferving the colour of its ftream during its paffage, and iffuing out at the weft fide of it in the territory of Dara. There is a ford, though very deep and dangerous, at the place where the Nile firft affumes the name of a ri¬ ver, after emerging from the lake Dembea *, but the ftream in other places is exceedingly rapid : the banks in the courfe of a few miles become very high, and are covered with the moft beautiful and variegated verdure that can be conceived. It is now confined by the mountains of Begemder, till it reaches Alata, where is the third cataraft. This, we are informed by Mr Bruce, is the moft magnificent fight he ever beheld ; but he thinks that the height has rather been exagger¬ ated by the miflionaries, who make it 50 feet; and after many attempts to meafure it, he is of opinion that it is nearly 40 feet high. At the time he vifited it, the ri¬ ver had been pretty much fwelled by rains, and fell in one fheet of water, without any interval, for the fpace of half an Englifh mile in breadth, with fuch a noife as ftunned and made him giddy for fome time. The ri¬ ver, for fome fpace both above and below the fall, was covered with a thick mift, owing to the fmall particles of the water dafhed up into the air by the violence of the (hock. The river, though fwelled beyond its ufual fize, retained its clearnefs, and fell into a natural bafon of rock ; the ftream appearing to run back againft the foot of the precipice over which it falls with great vio¬ lence ; forming innumerable eddies, waves, and being in exceflive commotion, as may eafily be imagined. Je¬ rome Lobo pretends that he was able to reach the foot of the rock, and fit under the prodigious arch of water fpouting over it} but Mr Bruce does not hefitate to pronounce this to be an abfolute falfehood. The noife of the cataract, which, he fays, is like the loudeft thun¬ der, could not but confound and deftroy his fenfe of hearing ; while the rapid motion of the water before his eyes would dazzle the fight, make him giddy, and ut¬ terly deprive him of all his intelleftual powers. “ It ■was a moft magnificent fight, (fays Mr Bruce), that ages, added to the greateft length of human life, would N I L not deface or eradicate from my memory : it ftruck me Nile, with a kind of ftupor, and a total oblivion of where I was, and of every other fublunary concern.” About half a mile below the catarad, the Nile is confined between two rocks, where it runs in a narrow channel with impetuous velocity and a great noife. At the village of Alata there is a bridge over it, confifting of one arch, and that no more than 23 feet wide. This bridge is ftrongly fixed into the folid rock on both fides, and fome part of the parapet ftill remains. No crocodiles ever come to Alata, nor are any ever feen be¬ yond the cataraft. Below this tremendous water-fall the Nile takes ft fouth-eaft diredtion, along the weftern fide of Begem¬ der and Amhara on the right, enclofing the province of Goiam. It receives a great number of ftreams from both fides, and after feveral turns takes at laft a direc¬ tion almoft due north, and approaches within 62 miles of its fource. Notwithftanding the vaft increafe of its waters, however, it is ftill fordable at fome fealbns of the year ; and the Galla crofs it at all times without any difficulty, either by fwimming, or on goats-fkins blown up like bladders. It is like wife crofted on fmall rafts, placed on two (kins filled with wind : or by twill¬ ing their hands round the tails of the horfes who fwim over ; a method always ufed by the women who follow the Abyffinian armies, and are obliged to crofs unford- able rivers. In this part of the river crocodiles are met with in great numbers ", but the fuperftitious people pre¬ tend they have charms fufficiently powerful to defend themfelves againft their voracity.—The Nile now feems to have forced its paffage through a gap in fome very high mountains which bound the country of the Gongas, and falls down a catarafl of 280 feet high ; and im¬ mediately below this are two others, both of very con¬ fiderable height. Thefe mountains run a great way to the weftward, where they are called Di/re or Teg/a, the eaftern end of them joining the mountains of Kuara, where they have the name of Fa%uclo. Thefe moun¬ tains, our author informs us, are all inhabited by Pagan nations ; but the country is lefs known than any other on the African continent. There is plenty of gold waflied down from the mountains by the torrents in the rainy feafon 5 which is the fine gold of Sennaar named Tibbar. The Nile, nowr running clofe by Sennaar in a direc¬ tion nearly north and fouth, makes afterwards a (harp turn to the eaft ; affording a pleafant view in the fair feafon, when it is brim-full, and indeed the only orna¬ ment of that bare and inhofpitable country. Leaving Sennaar, it paffes by many large towns inhabited by Arabs, all of them of a white complexion ; then paffing Gerri, and turning to the north-eaft, it joins the Ta- cazze, paffing, during its courfe through this country, a large and populous town named Cnendi, probably the Candace of the ancients. Here Mr Bruce fuppofes the ancient ifland or peninfula of Meroe to have been fitu- ated. Having at length received the great river Atba- ra, the Aftaboras of the ancients, it turns directly north for about two degrees ; then making a very unexpected turn weft by fouth for more than two degrees in longi¬ tude, and winding very little, it arrives at Korti, the firft town in Barabra, or kingdom of Dongola. From Kor¬ ti it runs almoft fouth-weft till it paffes Dongola, called alfo Bejci, the capital of Barabra ; after which it comes C a te [ 19 1 NIL to Mofcho, a corificierable town and place of refrefliment to the caravans when they were allowed to pais from Egypt to Ethiopia. From thence turning to the north-eaft ;t meets with a chain of mountains in about 22° 15' of N. latitude, where is tire feventh cataract named Jan Adel. This is likewife very tremendous, though not above half as high as that of Alata. This courfe is now continued till it falls into the Mediterra¬ nean • there being only one other cataract in the whole fpace, which is much inferior to any of thofe already defcribed. i bis verv particular and elaborate account of the fources of the Nile and of the courfe of the river given by Mr Bruce, hath not efcaped eriticifm. We find him accufed by the reviewers, not only of having brought nothing to light that was not previoully known to the learned, but even of having revealed nothing w hich was not previoully published in Guthrie’s Geographical Grammar. This, however, feems by no means a fair and candid critkdfm. If the fources of the Nile, as defcribed by Mr Bruce, were known to the author of Guthrie’s Grammar, they muft likewife have been fo to every retailer of geography fince the time of the miffionaries ; which, as the reviewers have particu¬ larized that book, would not feem to have been the cafe. If any thing new was publilhed there previous to the appearance of Mr Bruce’s work, it mutt pro¬ bably have been derived indireftly from himfelf j of which clandeftine method of proceeding that gentleman has had frequent occafion to complain in other cafes. It is alleged, however, that he has given the name of Uile to a ftream which does not deferve it. This, like all other large rivers, is compofed of innumerable branches ; to vilit the tojv of every one of which would be indeed an Herculean talk. The fource of the largeft branch, therefore, and that which has the longett courfe, is undoubtedly to be accounted the fource of the river*, but here it is denied that Mr Bruce had fufficient information. “ Of the innumerable ftreams (fay they) that feed the lake of Tzana, there is one that ends in a bog, to which Mr Bruce was condudled by Woldo, a lying guide, who told him it was the {burce of the Nile. Mr Bruce, in a matter of far lefs importance, would not have taken Woldo’s word ; but he is perfuaded, that in this cafe he fpoke truth 5 becaufe the credulous barbarians of the neighbouring diftridf paid fomething like worfnip to this brook, which, at the diftanee of 14 miles from its fource, is not 20 feet broad, and nowhere one foot deep. Now it is almoft unneceffary to obferve, that the natives of that country being, according to Mr Bruce’s report, pagans, might be expe&ed to worlhip the pure and fa- lutary ftream, to which, with other extraordinary quali¬ ties, their fuperftition aferibed the power of curing the bite of a mad dog. Had he traced to its {burce any of the other rivulets which run into the lake Tzana, it is not unlikely that he might have met with fimilar inftances of credulity among the ignorant inhabitants of its banks. Yet this would not prove any one of them in particular to be the. head of the Nile. It would be trifling with the patience of our readers to fay one word more on the queftion, whether the Por- tuguefe Jefuits or Mr Bruce difeovered what they er- foneoufly call the head of the Nile Before either they or he had indulged themfelves in a r ain triumph 20 J N I L over the labours of antiquity, they ought to have been Nile, lure that they had effe&ed what antiquity was unable v }' to aecomplilh. Now the river defcribed by the Jeluit Kircher, who colledted the information of his brethren, as well as by Mr Bruce, is not the Nile of which the ancients were in quell. This is amply proved by the prince of modern geographers, the incomparable D’An- viile (at leaft till our own Kennel appeared), in aSee-SW- copious memoir publilhed in the 26th volume ot the.^^J1^ Memoirs of the Academy of Belles Lettres, p. 45.— ^ ^ To this learned differtation we refer our readers \ add¬ ing only what feems probable from the writings of Diodorus Siculus and Herodotus, that the ancients had two meanings when they fpoke of the head or fource of the Nile : Firit, Literally, the head or lource of that great weflern ftream now called the White River, which contains a much greater weight of waters, and has a much longer courle than the river defcribed by the jefuits and by Mr Bruce : and, 2dly, Metaphorically, the caufe of the Nile’s inundation—■ This caufe they had difeovered to be the tropical rains, which fall in the extent of 16 degrees on each fide of the line ; which made the facriftan of Minerva’s temple of Sals in Egypt tell that inquifitive traveller HeroT dotus, that the waters of the Nile run in two oppolite directions from its fource *, the one north into Egypt, the other fouth into Ethiopia j and the reports of all travellers into Africa ferve to explain and confirm this obfervation. The tropical rains, they acknowledges, give rife to the Nile and all its tributary ftreams which flow northward into the kingdom of Sennaar, as well as to the Zebee, and fo many large rivers which fiow fouth into Ethiopia *, and then, according to the incli¬ nation of the ground, fall into the Indian or Atlantic ocean. Such then, according to the Egyptian priefts, is the true and philofophical iource ot the Nile ; a fource difeovered above 3000 years ago, and not, as Mr Bruce and the Jefuits have fuppofed, the head of a paltry rivulet, one of the innumerable ftreams that teed the lake Tzana.” On this fevere criticifm, however, it is obvious to re¬ mark, that if the fource of the Nile has been difeo¬ vered fo many years ago, there is not the leaft proba¬ bility that the finding of it fliould have been deemed an impoftible undertaking, which it molt certainly was, by the ancients.—That the finding out the fountains of the river itfelf was an objeft of their inquiry, can¬ not be doubted *, and from the accounts given by Mr Bruce, it appears very evident that none of the an¬ cients had equal fuccefs with himfelf ^ though indeed the Jefuits, as has already been obferved, feem to have a right to difpute it with him. From the corre- fpondence of his accounts with that of the Jefuits, it appears certain that the moft coniiderable ftream which flows into the lake Tzana takes its rife from the foun¬ tains, at Geefh already defcribed j and that it is the moft confiderable plainly appears from its ftream being vitible through the whole breadth of the lake, which is not the cafe with any of the reft. The preference given to this ftream by the Agows, who worflnp it, feems aifo an in- con teftable proof that they look upon it to be the great river which pafles through Ethiopia and Egypt ; nor will the argument of the reviewers hold good mfuppojing that other ftreams are worftiipped, unlefs they could prove that they are fo. As little can it be any objeftion or difparagement Nile. NIL [2 disparagement to Mr Bruce’s labours, that be did not difcover the Sources of the weftern branch of the Nile called the White River. Had he done_ fo, it might next have been objefted that he did not vifitthe Springs of the Tacazze, or any other branch. 'I hat the ori¬ gin of the White river was unknown to the ancients may readily be allowed ; but So were the fountains^ of Geelh, as evidently appears from the erroneous polition of the Sources of the eaftern brancli of the Nile laid down by Ptolemy. Our traveller, therefore, certainly has the merit, if not of discovering the Sources, at leaft of confirming the accounts which the Jefuits have given of the Sources, of the river called the Nile; and of ■which the White river, whether greater or Smaller, Seems to be accounted only a branch. The Superior ve¬ neration paid to the eaftern branch of this celebrated river will alfo appear from the variety of names given to it, as well as from the import of thefe names } of ■which Mr Bruce gives the following account. By the Agows it is named Gxeir, Geefa, or Setr; the firft of which terms fignifies a god. It is like- wife named Ab, father ; and has many other names, all of them implying the moft profound veneration. Having defeended into Gojam it is named Abay ; which, according to Mr Bruce, fignifies the river that Suddenly Swells and overflows periodically with rain. By the Gongas on the South fide of the mountains Dyre and Tegla, it is called Dahli, and by thofe on the north fide Kownfs; both of which names fignify a 'watching dog, the latrator anubis, or dog-far. In the plain country between Fazuclo and Sennaar it is called Nile, which fignifies blue; and the Arabs interpret this name by the word A%ergue ; which name it retains till it reaches Halfaia, where it receives the White river. Formerly the Nile had the name of Siris, both be¬ fore and after it enters Beja, which the Greeks ima¬ gined was given to it on account of its black colour during the inundation *, but Mr Bruce aflures us that the river has no Such colour. He affirms, with great probability, that this name in the country of Beja imports the river of the dog-far, on whofe vertical ap¬ pearance this river overflows ; “ and this idolatrous worfhip (Says he) was probably part of the reafon of the queftion the prophet Jeremiah afles: And what haft thou to do in Egypt to drink the water of 5eir> or the water profaned by idolatrous rites ?” As for the firft, it is only the tranflation of the word applied to the Nile. The inhabitants of the Barabra to this day call it Bahar el Nil, or the Sea of the Nile, in con- tradiftinflion to the Red Sea. for which they have no other name than Bahar el Molech, or the Salt Sea. The jundlion of the three great rivers, the Nile flowing on the weft fide of Meroe; the Tacazze, which wafhes the eaft fide, and joins the Nile at Maggiran in N. Lat. 17®; and the Mareb, which falls into this laft fomething above the junction, gives the name of Triton to the Nile. The name TEgyptus, which it has in Homer, and which our author fuppofes to have been a very an¬ cient name even in Ethiopia, is more difficult to ac¬ count for. This has been almoft univerfally fuppof- ed to be derived from the black colour of the inun¬ dation } but Mr Bruce, for the reafons already given, will not admit of this. “ Egypt (Says he) in the i ] NIL Ethiopic is called y Gipt, Agar ; and an inhabitant of Nil the country, Gypt, for precifely So it is pronounced 5 ^ which means the country of ditches or canals, drawn from the Nile on both fides at right angles with the river : nothing Surely is more obvious than to write y Gipt, So pronounced, Egypt; and, with its termina¬ tion us or or, Egyptus. The Nile is alSo called Kro- nides, Jupiter ; and has had Several other appellations beftowed upon it by the poets ; though theSe are ra¬ ther of a tranfitory nature than to be ranked among the ancient names of the river. By Some of the an¬ cient fathers it has been named Geon; and by a Strange train of miracles they would have it to be one of the rivers of the terreftrial paradife ; the fame which is Said to have encompafled the whole land of Cuth or Ethiopia. To effect this, they are obliged to bring the river a great number of miles, not only under the earth, but under the Sea alfo; but Such reveries need no refu¬ tation. Under the article Egypt we have So fully explained, the caufe of the annual inundation of the Nile, that, with regard to the phenomenon itfelf, nothing farther Seems neceffary to be added. We ihall therefore only extrabl from Mr Bruce’s work what he has faid con¬ cerning the mode of natural operation by which the tropical rains are produced •, which are now univerfally allowed to be the caufe of the annual overflowing of this and other rivers. According to this gentleman, the air is So much ra¬ refied by the fun during the time that he remains al¬ moft Stationary over the tropic of Capricorn, that the other winds loaded with vapours ruth in upon the land from the Atlantic ocean on the weft, the Indian ocean on the eaft, and the cold Southern ocean beyond the Cape. Thus a great quantity of vapour is gathered, as it were, into a focus ; and as the fame caufes con¬ tinue to operate during the progrefs of the fun north¬ ward, a vaft train of clouds proceed from South to north, which, Mr Bruce informs us, are Sometimes ex-, tended much farther than at other times. I hus he tells us, that for two years Some white dappled clouds were Seen at Gondar, on the 7th of January ; the fun being- then 340 diftant from the zenith, and not the leait cloudy Speck having been Seen for Several months be¬ fore. About the firft of March, however, it begins to rain at Gondar, but only for a few minutes at a time,, in large drops •, the fun being then about 50 diftant from the zenith. The rainy feafon commences with violence at every place when the fun comes direbtly over it ; and before it commences at Gondar, green boughs and leaves appear floating in the Bahar el Abiad, or White river, which, according to the accounts given by the Galla, our author fuppofes to take its rife in about 50 north latitude. The rains therefore precede the fun only about 50 j but they continue and increafe after he has paffed it. In April all the rivers in the Southern parts of Abyf- finia begin to Swell, and greatly augment the Nile, which is now alfo farther augmented by the vaft quan¬ tity of water poured into the' lake Tzana. On the firft days of May, the fun paffes the village of Gerri, which is the limit of the tropical rains ; and it is very remarkable, that, though the Sun ilill continues to operate with unabated vigour, ail his influence cannot bring the. clouds farther northward than this village \ NIL [ 22 1 NIL tlie reafon of which Mr Bruce, with great reafon, fup- pofes, to be the want of mountains to the northward. In confirmation of this opinion, he obferves, that the tropical rains flop at the latitude of 140 inftead of 160 in the weftern part of the continent. All this time, however, they continue violent in Abyflinia 5 and in the beginning of June the rivers are all full, and con¬ tinue fo while the fun remains llationary in the tropic of Cancer. This exceflive rain, which would fweep off the whole foil of Egypt into the fea were it to continue with¬ out intermiflion, begins to abate as the fun turns fouth- ward ; and on his arrival at the zenith of each place, on his paffage towards that quarter, they ceafe entire¬ ly : the reafon of which is no lefs difficult to be dif- covered than that of their coming on when he arrives at the Zenith in his paffage northward. Be the rea¬ fon what it will, however, the fadt is certain *, and not only fo, but the time of the rains ceafing is exaft to a lingle day; infomuch, that on the 25th of September the Nile is generally found to be at its higheft at Cairo, and begins to diminiffi every day after. Immediately after the fun has palled the line, he begins the rainy feafon to the fouthward 5 the rains conftantly coming on with violence as he approaches the zenith of each place ; but the inundation is now promoted in a different man¬ lier, according to the difference of circumftances in the iituation of the places. From about 6° S. Lat. a chain of high mountains runs all the way along the middle of the continent towards the Cape of Good Hope, and in- terfe&s the fouthern part of the peninfula nearly in the fame manner that the Nile does the northern. A ftrong wind from the fouth, flopping the progrefs of the con- denfed vapours, daffies them againfl the cold fummits of this ridge of mountains, and forms many rivers, which efcape in the direftion eilher of eaff or weft as the level prefents itfelf. If this is toivards the weft, they fall down the fides of the mountains into the Atlantic, and if on the eaft into the Indian ocean.—“ The clouds (fays Mr Bruce), drawn by the violent aflion of the fun, are condenfed, then broken, and fall as rain on the top of this high ridge, and fwell every river 5 while a wind from the ocean on the eaft blows like a monfoon, up each of thefe ftreams, in a direftion contrary to their current during the whole time of the inundation ; and this enables boats to afcend into the weftern parts of So- fala, and the interior country, to the mountains where lies the gold. The fame effeft, from the fame caufe, is produced on the weftern fide towards the Atlantic ; the high ridge of mountains being placed between the dif¬ ferent countries weft and eaft, is at once the fource of their riches, and of thofe rivers which conduft to the treafures, which would be otherwife inacceffible, in the eaftern parts of the kingdoms of Benin, Congo, and An¬ gola. “ There are three remarkable appearances attending the inundation of the Nile. Every morning in Abyffi- nia is clear, and the fun ffiines. About nine, a fmall cloud not above four feet broad, appears in the eaft, whirling violently round as if upon an axis ; but arri¬ ved near the zenith, it firft abates its motion, then lofes its form, and extends itfelf greatly, and feems to call ^ up vapours from all the oppofite quarters. Thefe clouds having attained nearly the fame height, ruffi againft each other with great violence, and put me always in mind of Eliffia foretelling rain on Mount Carmel. The air, impelled before the heavieft mafs, or fwifteft mover, makes an impreffion of its form on the colleftion of clouds oppofite ; and the moment it has taken poffeffion of the fpace made to receive it, the moft violent thun¬ der poffible to be conceivedinftantly follows, with rain; after fome hours the Iky again clears, Avith a wind at north : and it is always difagreeably cold when the ther¬ mometer is beloAv 63°. “ The fecond thing remarkable is the variation of the thermometer. When the fun is in the fouthern tropic, 36° diftant from the zenith of Gondar, it is feldom Ioav- er than 72° ; but it falls to 6o°, and 63°, when the fun is immediately vertical ; fo happily does the ap¬ proach of rain compenfate the heat of a too fcorching fun. “ The third is that remarkable flop in the extent of the rain nortlmard, Avhen the fun that has condufted the vapours from the line, and fhould feem norv more than ever to be in the poffeffion of them, is here over¬ ruled fuddenly ; till, on his return to Gerri, again it re¬ fumes the abfolute command over the rain, and recon- dufts it to the line, to furniffi diftant deluges to the foutliAA-ard.” With regard to the Nile itfelf, it has been faid that the quantity of earth brought doAvn by it from Abyffi- nia is fo great, that the whole land of Egypt is produ¬ ced from it. This queftion, hoAvever, is difcuffed under the article Egypt, where it is ffiown that this cannot poffibly be the cafe.—Among other authorities there quoted was that of Mr Volney, who ftrenuoufly argues againft the opinion of Mr Savary and others, who have maintained that Egypt is the gift of the Nile. Not- withftanding this, however, A\Te find him afferting that the foil of Egypt has undoubtedly been augmented by the Nile, in wffiich cafe it is not unreafonable to fup- pofe that it has been produced by it altogether.—“ The reader (fays he) will conclude, doubtlefs, from what I have faid, that Avriters have flattered themfelves too much in fuppofing they could fix the preeife limits of the enlargement and rife of the Delta. But, though I would rejeft all illufory circumftances, I am far from denying the faft to be Avell founded j it is plain from reafon, and an examination of the country. The rife of the ground appears to me demonftrated by an obfer- vation on Avhich little ftrefs has been laid. In going from Rofetta to Cairo, when the Avaters are Ioav, as in the month of March, Ave may remark, as Ave go up the river, that the ffiore rifes gradually above the Avater 5 fo that if overfloAved tAVo feet at Rofetta, it overfloAvs from three to four at Faona, and upAvards of tAvelve at Cairo (a). Now by reafoning from this faft, Ave may deduce the proof of an increafe by fediment 5 for the layer of mud being in proportion to the thicknefs of the ffieets of Avater by which it is depofited, muft be more or lefs confiderable Nile. (a) “It Avould be curious to afcertain in what proportion it continues up to Afouan. Some Copts, Avhom I have interrogated on the fubjeft, affured me that it Avas much higher through all the Said than at Cairo.” NIL [ 23 ] NIL Nile. confiderable as thefe are of a greater or lefs depth j and xvq have feen that the like gradation is obfervable from Alouan to the fea. “ On the other hand, the increafe of the Delta ma- nifefts itfelf in a linking manner, by the form of Egypt along the Mediterranean. When we confider its figure on the map, we perceive that the country which is in the line of the river, and evidently formed of foreign materials, has affumed a femicircular lhape, and that the Ihores of Arabia and Africa, on each fide, have a direc¬ tion towards the bottom of the Delta ; which manifellly difcovers that this country was formerly a gulf, that in time has been filled up. “ This accumulation is common to all rivers, and is accounted for in the fame manner in all: the rain wa¬ ter and the fnow defcending from the mountains into the valleys, hurry inceflantly along with them the earth they wadi away in their defcent. The heavier parts, fuch as pebbles and fands, foon flop, unlefs for¬ ced along by a rapid current. But when the waters meet only with a fine and light earth, they carry away large quantities with the greateft facility. The Nile, meeting with fuch a kind of earth in Abyffinia and the interior parts of Africa, its waters are loaded and its bed filled with it ; nay, it is frequently fo embar- rafled with this fediment as to be ftraitened in its courfe. But when the inundation reftores to it its natural energy, it drives the mud that has accumu¬ lated towards the fea, at the fame time that it brings down more for the enfuing feafon 5 and this, arrived at its mouth, heaps up, and forms ihoals, where the declivity does not allow fufficient adtion to the cur¬ rent, and where the fea produces an equilibrium of refiftance. The flagnation which follows occafions the grofler particles, which till then had floated, to fink ; and this takes place more particularly in thofe places where there is leaf! motion, as towards the fhores, till the fides become gradually enriched by the fpoils of the upper country and of the Delta itfelf; for if the Nile takes from Abyflinia to give to the Thebais, it likewife takes from the Thebais to give to the Delta, and from the Delta to carry to the fea. Wherever its waters have a current, it defpoils the fame territory that it enriches. As we afcend towards Cairo, when the river is low, we may obferve the banks worn deep on each fide and crumbling in large flakes. The Nile, w’hich undermines them, depriving their light earth of fupport, it falls into the bed of the ri¬ ver ; for when the water is high, the earth imbibes it; and when the fun and drought return, it cracks and moulders away in great flakes, which are hurried along by the Nile.” Thus does Mr Volney argue for the increafe of the Delta in the very fame manner that others have ar¬ gued for the production of the whole country of Egypt; an opinion which he is at great pains to refute. Under the article Egypt, however, it is fhown that the Nile does not bring down any quantity of mud fufficient for the purpofes affigned 5 and with regard to the argu¬ ment drawn from the ffiallowmefs of the inundation when near the fea, this does not prove any rife of the land ; but as Mr Rennel has iudicroufly obferved in his remarks on the inundation of the Ganges, arifes from the nature of the fluid itfelf. The reafon, in ffiort, is this; 1 he furface of the fea is the lo'weft point to which 3 the waters of every inundation have a tendency j and when they arrive there, they fpread themfelves over it with more eafe than anywhere elfe, becaufe they meet with lefs refiitance. Their motion, however, by reafon of the fmall declivity, is lefs fwift than that of the waters farther up the river, where the declivity is greater j and confequently the latter being fomewhat impeded in their motion, are in fume degree accumulated. The furface of the inundation, therefore, does not form a perfeftly level plain, but one gradually doping from the interior parts of the country towards the fea 5 fo that at the greatefl: diftance from the ocean the water will always be deepeft, even if we fliould fuppofe the whole country to be perfectly fmooth, and compofed of the molt folid materials.—This theory is eafily underftood from obferving a quantity of water running along a wooden fpout, which is always more (hallow at the end of the fpout where it runs olf than at the others.— With regard to Mr Volney’s other arguments, they are without doubt contradictory 5 for if, as he fays, the river takes from Abyffinia to give to the Thebais, from Thebais to give to the Delta, and from Delta to the fea, it undoubtedly follows, that it gives nothing to any part of the land whatever, but that altogether is fwept into the Mediterranean fea, which, indeed, feme very trifling quantities excepted, is mod probably the cafe. It has been remarked by Mr Pococke, a very judi¬ cious traveller, that in the beginning of the inunda¬ tion, the waters of the Nile run red, and fometimes green ; and while they remain of that colour, they are unwholefome. He explains this phenomenon by fup- pofing, that the inundation at firfl: brings away that red or green filth which may be about the lakes where it takes its rife ; or about the fources of the fmall rivers which flow into it, near its principal fource •, “ for, fays he, although there is fo little water in the Nile when at lowed, that there is hardly any current in many parts of it, yet it cannot be fuppofed that the water ffiould dagnate in the bed of the Nile fo as to become green. Afterwards the water begins to be red and dill more turbid, and then it begins to be wholefome.” This cir- cumdance is explained by Mr Bruce in the following manner : the country about Narea and Caffa, where the river Abiad takes its rife, is full of immenfe marlhes, where, during the dry feafon, the water flagnates, and becomes impregnated with every kind of corrupted mat¬ ter. Thefe, on the commencement of the rains, over¬ flow into the river Abiad, which takes its rife there. The overflowing of thefe vafl marffies fird carries the difcoloured water into Egypt; after which follows that of the great lake Tzana, through which the Nile paffes ; which having been dagnated, and without rain, under a fcorching fun for fix months, joins its putrid waters to the former. In Abyffinia alfo, there are very few ri¬ vers that run after November, but all of them dand in prodigious pools, which, by the heat of the fun, likewife turn putrid, and on the commencement of the rains throw' off their dagnant water into the Nile •, but at lad, the rains becoming condant, all this putrid matter is carried off, and the fources of the inundation become fweet and wholefome. The river then paffing through the kingdom of Sennaar, the foil of which is this red bole, becomes coloured with that earth ; and a mixture, along with the moving fands of the deferts, of which it receives Nile. V NIL F 24 1 NIL receives a great quantity when raifcd by the wind, pre¬ cipitates ail the vifcous and putrid matters which float in the waters j whence Mr Pococke judicioufly obferves, that the Nile is not wholefome when the water is clear and green, but when fo red and turbid that it ftains the Avater of the Mediterranean. The rains in Abyffinia, which ceafe about the 8th of September, generally leave a fickly feafon in the low country •, but the difeafts produced by thefe rains are re¬ moved by others Avhich come on about the end of Oc¬ tober, and ceafe about the 8th of November. On thefe rains depend the latter crops of the Abyflinians-, and for thefe the Agorvs pray to the rfoer, or the genius or fpirit refiding in it. In Egypt, however, the effeft of them is feldom perceived ; but in feme years they prove exceflive 5 and it has been obferved that the Nile, after it has fallen, has again rifen in fuch a manner as to alarm the whole country. This is faid to have hap¬ pened in the time of Cleopatra, when it was fuppofed to prefage the extinction of the government of the Ptole¬ mies ; and in 1737 it Avas likeAvife imagined to portend fome dreadful calamity. The quantity of rain, by which all this inundation is occafioned, varies confiderably in different years, at leaft at Gondar, Avhere Mr Bruce had an opportu¬ nity of meafuring it. In 1770 it amounted to 35^ inches j but in 1771 it amounted to no lefs than 4X,355 inches from the vernal equinox to the 8th of September. What our author adds concerning the variation of the rainy months feems totally irrecon¬ cilable with Avhat he had before advanced concerning the extreme regularity of the natural caufes by Avhich the tropical rains are produced. “ In 1770 (fays he) Auguft was the rainy month ; in 1771, July. When July is the rainy month, the rains generally ceafe for fome days in the beginning of Auguft, and then a prodigious deal falls in the latter end of that month and firlt Aveek of September. In other years July and Auguft are the violent rainy months, Avhile June is fair. And laftly, in others, May, June, July, Auguft, and the firft Aveek of September.” If this is the cafe, Avhat becomes of the regular attraction of the clouds by the fun as he advances northAvards ; of the coming on of the rains when he arrives at the zenith of any place, in his paffage to the tropic of Cancer ; and of their ceafing when he comes to the lame point in his re¬ turn fouthward ? Under Abyssinia Ave have mentioned a threat of one of the Abyffinian monarchs, that he Avould direft the courfe of the Nile and prevent it from fertilizing the land of Egypt; and it has likeAvife been related, that conliderable progrefs was made in this under¬ taking by another emperor. Mr Bruce has bellow¬ ed an entire chapter on the fubjeCland is of opinion, that “ there feems to be no doubt that it is poflible to di mini Hi or divert the courfe of the Nile, that it fhould be infufficient to fertilize the country of Egypt; becaufe the Nile, and all the rivers that ruit into it, and all the rains that fwell thefe rivers, fall in a coun¬ try two miles above the level of the fea ; therefore it cannot be denied, that there is level enough to divert many of the rivers into the Red fea, or perhaps ftill ■ calier by turning the courfe of the river Ab’ad till it meets the level of the Niger, or pafs through the defert into the Mediterranean.” Alphonfo Albuquerque is faid to have Avritten frequently to the king of Por- Nile, tugal to fend him pioneers from Madeira, Avith people accuitomed to level grounds, and prepare them for fu- gar canes ; by whole afliftance he meant to turn the Nile into the. Red fea. This undertaking, however, if it really had been projected, wras never aceomplilhed ; nor indeed is there any probability that ever fuch a mad attempt ivas propofed. Indeed, though Ave cannot deny that there is a pollibility in nature of accomplilhing it, yet the vaft dithculty of turning the courfe of fo many large rfoers may jultly ftigmatize it as impracticable ; not to mention the obftaeles which muft naturally be fuggefted from the apparent inutility of the undertak¬ ing, and thofe Avhich would arife from the oppolition of the Egyptians. It has already been obferved in a quotation from the reviewers, that Herodotus Avas informed by the facriftan or fecretary of the treafury of Minerva, that one half of the Avaters of the Nile run north and the other fouth. This is alfo taken notice of by Mr Bruce; Avho gi\res the folloAving explanation of it. “ The fecretary Avas probably of that country himfelf, and feems by his obfervation to have knoAvn more of it than all the ancients together. In faCt Ave have feen, that betAveen 130 and 140 north latitude, the Nile, Avith all its tributary ftreams, Avhich have their rife and courfe AArithin the tropical rains, falls doAvn into the flat country (the kingdom of Sennaar), which is more than a mile loAver than the high country in Abyf¬ finia ; and thence, Avith a little inclination, it runs into Egypt. Again, In latitude 90, in the kingdom of Gin- giro, the Zebee runs fouth or fouth-eaft, into the Inner Ethiopia, as do alfo many other rivers, and, as I have heard from the natives of that country, empty themfelves into a lake, as thofe on the north fide of the line do into the lake Tzana, thence diftributing their Avaters to the eaft and weft. Thefe become the heads of great rivers, that run through the interior countries of Ethiopia (cor- refponding to the fea coaft of Melinda and Mombaza) into the Indian ocean ; Avhilft, on the weftward, they are the origin of the vaft ftreams that fall into the At¬ lantic, paffmg through Benin and Congo, fouthward of the river Gambia and the Sierra Leona. In Ihort, the periodical rains from the tropic of Capricorn to the line, being in equal quantity with thofe that fall be- tAveen the line and the tropic of Cancer, it is plain, that if the land of Ethiopia Hoped equally from the line fouth Avard and northAvard, the rains that fall Avould go the one half north and the other half fouth ; but as the ground from 30 north declines all fouthAvard, it fol- Ioavs, that the rivers which run to the fouth Avard muft be equal to thofe that run nortlnvard, p/us the rain that foils in the north latitude, Avhere the ground begins to Hope to tin fouthAvard; and there can be little doubt that is at leaft one of the reafons Avhy there are in the fouthern continent fo many rivers larger than the Nile, that run both into the Indian and Atlantic oceans.” From this account given to Herodotus, it has been fuppofed, by fome writers on geography, that the Nile divides itfelf into two branches, one of which runs nortliAvard into Egypt, and one through the country of the Negroes weft Avard into the Atlantic ocean. This opinion Avas firft broached by Pliny.— It has been adopted by the Nubian geographer, Avlr> urges NIL [2 Nile, urges in ’fupport of it, that if the Nile carried down —v—-'all ’ the rains which fall into it from Abyffinia, the people of Egypt would not be fafe in their houfes. But to this Mr Bruce anfwers, that the wafte of wa¬ ter in the burning deferts through which the Nile paffes is fo great, that unlefs it was fupplied by an¬ other dream, the White River, equal in magnitude to itfelf, and which, riling in a country of perpetual rains, is thus always kept full, it never could reach Egypt at all, but would be loft in the fands, as is the cafe with many other very conliderable rivers in A- frica. “ The rains (fays he) are colleaed by the four great rivers in Abyffinia ■, the Mareb, the Bowiha, the Taoazze, and the Nile. All thefe principal, and their tributary ftreams, would, however, be abforbed, nor be able to pafs the burning deferts, or find their way into Egypt, were it not for the White River, which having its fource in a country of almoft perpe¬ tual rains, joins to it a never-failing ftream equal to the Nile itfelf.” We {hall conclude this article with fome account of the Agows who inhabit the country about the fources of the Nile. Thefe, according to Mr Bruce, are one of the moft confiderable nations in Abyffinia, and can bring into the field about 4000 horfe and a great number of foot; but were once much more powerful than they are now, having been greatly re¬ duced by the invafions of the Galla. Their province is nowhere more than 6a miles in length, or than 30 in breadth •, notwithftanding which they fupply the capital and all the neighbouring country with cattle, honey, butter, wax, hides, and a number of other ne- eeffary articles *, whence it has been cuftomary for the Abyffinian princes to exaft a tribute rather than mili¬ tary fervice from them. The butter is kept from pu¬ trefaction during the long carriage, by mixing it with a fmall quantity of a root fomewhat like a carrot, which they call mormoco. It is of a yellow colour, and an¬ swers the purpofe perfectly well; which in that climate it is very doubtful if fait could do. The latter is be- fides ufed as money ^ being circulated inftead of filver coin, and ufed as change for gold. Brides paint their feet, hands, and nails, with this root. A large quan¬ tity of the feed of the plant Avas brought into Europe by Mr Bruce. The AgoAvs carry on a confiderable trade Avith the Shangalla and other black favages in the neighbour¬ hood ; exchanging the produce of their country for gold, iv'ory, horns of the rhinoceros, and fome fine cot¬ ton. The barbarity and thievifh difpofition of both nations, hoAvever, render this trade much inferior to Avhat it might be. In their religion the Agotvs are grots idolaters, pay¬ ing divine honours to the Nile, as has already been ob- ferved. Mr Bruce, who lodged in the houfe*of the prieft of the river, had an opportunity of becoming ac¬ quainted Avith many particulars of their devotion. He heard him addrefs a prayer to the Nile, in Avhich he ftyled it the “ Moft High God, the Saviour of the world.” In this prayer he petitioned for feafonable rain, plenty of grafs, and the prefervation of a kind of ferpents ; deprecating thunder very pathetically. The moft fublime and lofty titles are given by them to the fpirit Avhich they fuppofe to refide in the river Nile ; calling it everlafting God, Light of the World, Eye of Vol. XV. Part I. ; ] NIL the World, God of Peace, their Saviour, and Father of Nile, r t • c Nilometer. the Umverie. > ^ a The AgoAvs are all clothed in hides, which they ma- nufacture in a manner peculiar to themfelves. Thefe hides are made in the form of a Hurt reaching down to their feet, and tied about the middle Avith a kind of falh or girdle. The lower part of it refembles a large double petticoat, one fold of Avhich they turn back over their Ihoulders, faftening it Avith a broach or Ike AV¬ er acrols their breaft before, and the married Avomen carry their children in it behind. The younger fort generally go naked. The Avomen are marriageable at nine years of age, though they commonly do not marry till eleven ; and they continue to bear children till 30, and iometimes longer. They are generally thin and be¬ low the middle fize, as Avell as the men. Barrennefs is quite unknoAvn among them. The country of the Agows has a very elevated litua- tion, and is of courfe fo temperate that the heat may eafily be borne, though little more than io° from the equator. The people, hoAvever, are but Ihort lived ; Avhich may in part be owing to the oppreffion they la¬ bour under. This, according to Mr Bruce, is cxceffive. “ Though their country (fays he) abounds Avith all the neceffaries of life, their taxes, tributes, and ferviees, efpe- cially at prefent, are fo multiplied upon them, Avhilft their difirefles of late have been lb great and frequent, that they are only the manufacturers of the commodities they fell, to fatisfy thefe conftant exorbitant demands, and cannot enjoy any part of their oavo produce themfelves, but live in penury and mifery fcarcely to be conceived. We faAv a number of Avomen Avrinkled and fun-burnt fo as fcarcely to appear human, Avandering about under a burning fun, Avith one and fometimes two children upon their backs; gathering the feeds of beut grafs to make a kind of bread.” NILOMETER, or Niloscope, aninftrument ufed among the ancients to meafure the height of the Avater of the river Nile in its overflowings. The Avord comes from NsfAfl?, Nile (and that from net “ neAV mud,” or as fome others Avould have it, from no), “ I floAv,” and tXvg, u mud,”) and ^sr^ey, “ meafure.” The Greeks more ordinarily call it, Ne<- ?>otrx.o7rtov. The nilometer is faid, by feveral Arabian Avriters, to have been firft fet up, for this purpofe, by Jofeph during his regency in Egypt : the meafure of it Avas 16 cubits, this being- the height of the increafe of the Nile, Avlnch was neceffary to the fruitfulnefs of Egypt. From the meafure of this column, I)r Cumberland * * Scripture deduces an argument, in order to prove that the JeAvifli and Egyptian cubits were of the fame length. fines, p. iS, In the French king’s library' is an Arabic treatife on nilometers, entitled JVW/ Ji alnal al Nil; Avherein are deferibed all the overflowings of the Nile, from the firft year of the Hegira to the 875th. Herodotus mentions a column erected in a point of the ifland Delta, to ferve as a nilometer 5 and there is ftill one of the fame kind in a mofque of the fame place. As all the riches of Egypt arife from the inundations of the Nile, the inhabitants ufed to fupplicate them at the hands of their Serapis ; and committed the moft execrable crimes, as actions, forfooth, of religion, to ob¬ tain the favour. This occafioned Conftantine exprefsly D to N I M [ 26 ] N I M Kilometer to prohibit thefe facrifices, &c. and to order the nilo- ^r. II meter to be removed into the church 5 whereas, till 7 ^ ‘ that time, it had been in the temple of Serapis. Julian the Apoftate had it replaced in the temple, where it continued till the time of Theodolite the Great. The following is Mr Bruce’s account of the nilome- -}■ Bmce's ter. “ On the point f of the ifland Rhode, between Trawls, Geeza and Cairo, near the middle of the river, is a mi. Li. round tower encloling a neat well or ciftern lined with marble. The bottom of this well is on the fame levt-1 with the bottom of the Nile, which has free accefs to it through a large opening like an embrafure. In the middle of the 'well rifes a thin column of eight faces of blue and white marble of which the foot is on the fame plane with the bottom of the river. This pillar is di¬ vided into 20 peeks, of 22 inches each. Of thefe peeks the two lowermoft are left, without any divilion, to Rand for the quantity of fludge which the water depofits there. Two peeks are then divided, on the right hand, into 24 digits each ; then on the left, four peeks are divided into 24 digits 5 then on the right, four j and on the left another four : again, four on the right, which completes the number of 18 peeks from the firfl divilion marked on the pillar, each peek being 22 inches. Thus the whole marked and unmarked amounts to fomething more than 36 feet English.” On the night of St John, when, by the falling of the dew, they perceive the rain water from Ethiopia mixed with the Nile at Cairo, they begin to announce the ele¬ vation of the river, having then five peeks of water marked on the nilometer, and two unmarked for the Rudge, of which they take no notice. Their firR pro¬ clamation, fuppofing the Nile to have rifen 12 digits, is 12 from 6, or it wants 12 digits to be 6 peeks. When it has rifen three more, it is nine from fix ; and fo on, till the W’hole 18 be filled, when all the land of Egypt is fit for cultivation. Several canals are then opened, which convey the rvater into the defert, and hinder any further flagnation on the fields. There is indeed a great deal of more water to come from Ethiopia ; but wrere the inundation fuffered to go on, it would not drain foon enough to fit the land for tillage : and to guard againR this mifthief is the principal ufe of the nilome¬ ter, though the TurkiRr government makes it an engine of taxation. From time immemorial the Egyptians paid, as tribute to the king, a certain proportion of the fruit of the ground } and this was anciently afeertained by the elevation of the wTater on the nilometer, and by the menfuration of the land aftually overflowed. But the Saracen government, and afterwards the Turkifh, has taxed the people by the elevation alone of the wa¬ ter, without attending to its courfe over the country, or the extent of the land aflually overflowed 5 and this tax is fometimes cruelly oppreflive. NIMBUS, in antiquity, a circle obferved on certain medals, or round the heads of fome emperors j anfw'ering to the circles of light drawn round the images of faints. NIMEGUEN, a large, handfome, and flrongtown of the Netherlands, and capital of Dutch Guelderland, with a citadel, an ancient palace, and feveral forts. It is noted for the peace concluded there in 1695. It has a magnificent townhoufe, and the inhabitants are great¬ ly given to trade. It is feated on the Vahal or Wahal, between the Rhine and the Maefe. It is the utmoR eaflern boundary of the Netherlands. It contains two I Dutch churches, a French Calvinifl and a Lutheran Nimeguen church, five Popifli, and feveral hofpitals. It was once II a Hans town and an imperial city. It was once the ,7Vwi- rot*- feat of government, has a canal to Arnheim, and confi- derable trade to fome parts of Germany : it trades alfo in fine beer brewing, fattening of Cattle, and exporting of its butter, which is extremely good, into all the o- ther provinces. It was taken by the French in 1794. It is in E. Long. 3. 45. N. Lat. 51. 55. NIMETUL AHITES, a kind of Turkiflr monks, fo called from their founder Nimetulahi, famous for hi* dodlrines and the auRerity of his life. NIMPO, a city and feaport town of China, in the province of Chekiang. It is feated on the eallerii tea of China, over againR Japan. It is a city of the firR rank, and Rands at the confluence of two fmall rivers, which, after their union, form a channel that reaches to the fea, and is deep enough to bear veflels of 200 tons burden. The walls of Nimpo are 5000 paces in circum¬ ference, and are built with freeitene. There are five gates, befides two water gates for the palfage of barks in¬ to the city j a tower feveral Rories high, built of bricks; and a long bridge of boats, fattened together with iron chains, over a very broad canal. The city is command¬ ed by a citadel built on a very high rock, by the foot of which all veffels mufl neceffarily pafs. The Chinefe merchants of Siam and Batavia go to this place yearly to buy filks, which are the finelt in the empire. They have alfo a great trade with Japan, it being but two days fail from hence : thither they carry filks, fluffs, fu- gar, drugs, and wine ; and bring back copper, gold, and filver. E. Long. 122. O. N. Lat. 30. o. NIMROD, the fixth fon of Cufli, and in all appear¬ ance much younger than any of his brothers: for Mofes mentions the fons of Raamah, his fourth brother, before he fpeaks of him. . What the facred hiflorian fays of him is Riort; and yet he fays more of him than of any other of the poflerity of Noah, till he comes to Abra¬ ham. He tells us, that “ Nimrod began to be a mighty one in the earth that he was “ a mighty hunter be¬ fore the Lord,” even to a proverb ; and that “ the be¬ ginning of his kingdom vras Babel, and Erech, and Ac- cad, and Calneh, in the land of Shinar.” From this account he is fuppofed to have been a man of extraordinary flrength and valour. Some reprefent him as a giant; all confider him as a great warrior. It is generally thought, that by the words a mighty hunter, is to be underflood, that he was a great tyrant; but fome of the rabbins interpret thofe words favourably, faying that Nimrod rvas qualified by a peculiar dex¬ terity and flrength for the chafe, and that he offered to God the game which he took ; and feveral of the mo¬ derns are of opinion, that this paffage is not to be un¬ derflood of his tyrannical oppreflions, or of hunting of men, but of beafls. It mutt be owned that the phrafe before the Lord may be taken in a favourable fenfe, and as a commendation of a perfon’s good qualities ; but in this place the generality of expofitors underfland it otherwife. Hunting mufl have been one of the mofl ufeful em¬ ployments in the times juR after the difperfion, when all countries were overrun with wild beafls, of which it was neceffary they fliould be cleared, in order to make them habitable ; and therefore nothing feemed more proper to procure a man efleem and honour'in thofe ages,. N I M [ 27 ] N I N Nimrod, ages than his being an expert hunter. By that exercife, “""v we are told, the ancient Perfians fitted their kings for war and government ; and hunting is ftill, in many countries, coniidered as one part of a royal education. There is nothing in the (hurt hiftory of Nimrod which carries the lead air of reproach, except his name, which fignifies a rebel; and that is the circumftance which feems to have occafioned the injurious opinions which have been entertained of him in all ages. Commenta¬ tors, being prepoffeffed in general that the curfe of Noah fell upon the pofterity of Ham, and finding this prince ftigmatized by his name, have interpreted every paffage relating to him to his difad vantage. They reprefent him as a rebel againll God, in perfuading the defeendants of Noah to difobey the divine command to difperfe, and in fetting them to build the tower of Babel, with an impious defign of fealing heaven. They brand him as an ambitious ufurper, and an infolentopprefior \ and make him the author of the adoration of fire, of idolatrous w or {hip given to men, and the firft perfecutor on the fcore of religion. On the other hand, fome account him a virtuous prince, who, far from advifing the build¬ ing of Babel, left the country, and went into Afiyria, becaufe he would not give his confent to that projeft. Nimrod is generally thought to have been the firll king after the Hood ; though fome authors, fuppofing a plantation or difperfion prior to that of Babel, have made kings in feveral countries before his time. Miz- raim is thought, by many who contend for the antiquity of the Egyptian monarchy, to have begun his reign much earlier than Nimrod ; and others, from the uni¬ formity of the languages fpoken in Affyria, Babylonia, Syria, and Canaan, affirm thofe countries to have been peopled before the confufion of tongues. The four cities Mofes gives to Nimrod conftituted a large kingdom in thofe early times, when few kings had more than one j only it muft be obferved, that poflef- fions might at firft: have been large, and afterwards divi¬ ded into feveral parcels •, and Nimrod being the leader of a nation, we may fuppofe his fubjecls fettled within thofe limits : whether he became poffeffed of thofe cities by conqueft or otherwife, does not appear ; it is moft probable he did not build Babel, all the pofterity of Noah feeming to have been equally concerned in that affair; nor does it appear that he built the other three, though the founding of them, and many more, with other works, are attributed to him by fome authors. It may feem alfo a little ftrange, that Nimrod fhould be preferred to the regal dignity, and enjoy the moft culti¬ vated part of the earth then known, rather than any other of the elder chiefs or heads of nations, even of the branch of Ham. Perhaps it was conferred on him for his dexterity in hunting; or, it may be, he did not af- fume the title of king till after his "father Cufti’s death, who might have been fettled there before him, and left him the fovereignty ; but we incline to think, that he feized Shinar from the defeendants of Shem, driving out Affiur, who from thence went and founded Nineveh, and other cities in Affyria. The Scripture does not inform us when Nimrod be¬ gan his reign : Some date it before the difperfion ; but fueh a conje. adoration to his god Nifroch in his temple (2 Kings xix. 37.)• ^ is not known who this god Nif¬ roch was. The Septuagint calls him Mefrach, Jofe- phus calls him Arafkes. The Hebrew of Tobit pub- lifhed by Man Iter calls him Dagon. rI he Jews have a itrange notion concerning this deity, and fancy him to have been a plank of Noah’s ark. Some think the word fignifies a dove *, and others underftand by it an eagle, which has given occafion to an opinion, that Jimiter Belus, from whom the Afiyrian kings pretend¬ ed to be derived, was worfhipped by them under the form of an eagle, and called Nifroch. Our poet Mil- ton [fives this name to one of the rebel angels. • In the affembly next up flood Nifroch, of principalities the prince. Par. Lojl, book vi. 447. NISSOLIA, a genus of plants belonging to the diadelphia clafs, and in the natural method ranking under the 32d order, PapiUonacece. See Botany In¬ dex. NITHSDALE, NithisdalE, or Niddifdale. a dif- tridt of Dumfrksfhire in Scotland, lying to the weft- ward of Annandale. It is a large and mountainous traft, deriving its name from the river Nid, or Nith, which rifes on the borders of Ayrfhire, and runningby Sanquhar and Dumfries, difeharges itfelf into the Solway frith. This country was formerly fhaded with noble forefts, •which are now almoft deftroyed 5 fo that at prefent, no¬ thing can be more naked, wild, and favage. Yet the bowels of the earth yield lead, and, as is faid, fllver and gold : the mountains are covered with (beep and black cattle \ and here are ftill fome confiderable remains of the ancient woods, particularly that of Holywood, three miles from Dumfries, noted for a handfome church, built out of the ruins of an ancient abbey •, and alfo for being the birthplace of the famous aftrologcr, hence called Joannes de Sacro Bofco. Mr Pennant calls it a beautiful vale, improved in appearance by the bold curvatures of the meandering ftream, and for fome fpace, he fays, it is adorned with groves and gentlemen’s feats. NITOCRIS, the mother of Belfhazzar (whofe fa¬ ther was Evil Merodach and his grandfather Nebu¬ chadnezzar), was a woman of extraordinary abilities \ fhe took the burden of all public affairs upon herfelf; and, while her fon followed his pleafures, did all that could be done by human prudence to fuftain the tot¬ tering empire. She perfected the works Avhich Ne¬ buchadnezzar had begun for the defence of Babylon ; raffed ftrong fortifications on the fide of the river, and caufed a wonderful vault to be made under it. lead¬ ing from the old palace to the new, 12 feet high and 15 wide She likewife built a bridge acrofs the Eu¬ phrates, and accompliflied feveral other works, which were afterwards aferibed to Nebuchadnezzar. Philo- ftrates, in deferibing this bridge, tells us, that it was built by a queen, who was a native of Media •, whence we may conclude this illuftrious queen to have been by birth a Mede. Nitoeris is faid to have placed her tomb over one of the moft remarkable gates of the city, with an infeription to the following effefl : If any king of Babylon after me Jhall be in diflrefs i ] N I V for money, he may open this fepulchre, and take out as Nitocris much as may feme him ; but if he be in no real necejjity, . *1 . let him forbear, or he Jhall have caufe to repent of his fivein01' prefumption. This monument and infeription are faid to have re¬ mained untouched till the reign of Darius, who, con- fldering the gate was ulelefs, no man caring to pafs under a dead body, and being invited by the hopes of an immenfe treafure, broke it open ; but, inftead of what he fought, i-> iaid to have found nothing but a corpfe 5 and another infeription, to the following effe<5l : Hadji thoit not been mojl tnfatiably avaricious and greedy of the mojl fordid gain, thou wouldjl never have Violated the abode of the dead. NITHRARIA, a genus of plants belonging to the dodeeandria clafs, and in the natural method ranking with thofe of which the order is doubtful. See Botany Index. NITRE, Saltpetre, or Nitrate of Potafh. See Chemistry, N° 938, etfeq. Calcareous NlTliE. See LlME, Nitrate of, CHEMIS¬ TRY Index. NITROUS, any thing impregnated with nitrous air. Nitrous Air. See Azote, Chemistry Index. NIVELLE, a town of the Auftrian Netherlands, in the province of Brabant, remarkable for its abbey of canoneffes. Here is a manufacture of cambrics, and the town enjoys great privileges. The abbey juft mentioned is inhabited by young ladies of the firft quality, who are not confined therein as in nunneries, but may go out and marry whenever they fee conve¬ nient, or a proper match offers. E. Long. 4. 36. N. Lat. 50. 35. NlVELLE de la Chauffee (Peter Claude), a comic poet, born in Paris ; acquired great reputation by in¬ venting a new kind of entertainment, which was call¬ ed the Weeping Comedy. Inftead of imitating Arifto- phanes, Terence, Moliere, and the other celebrated comic poets who had preceded him ; and inftead of exciting laughter by painting the different ridiculous characters, giving ftrokes of humour and abfurdities in conduct 5 he applied himfelf to reprefent the weak- neffes of the heart, and to touch and foften it. In this manner he wrote five comedies : 1. La fauffe An- tipathie. 2. Le Prejuge a /a Mode; this piece met with great fuccefs. 3. Melanide. 4. Amour pour Amour; and, 5. HKcole des Meres. He was received into the French academy in 1736 ; and died at Paris in 1754, at 63 years of age. He alfo wrote a tragedy, entitled, Maximianus ; and an epiftle to Clio, an ingenious di- dadlic poem. N1VERNOIS, an inland province of France, with the title of a duchy, lying on the weft fide of Burgundy, and between it, Bourbonnois, and Barri. It is pretty fertile in wine, fruit, and corn *, except the part called Moment, which is a mountainous country, and bar¬ ren. There is a great deal of wood,'and feveral iron mines 5 as alfo mines of pit coal, which ferves to work their forges. This province is watered by a great number of rivers ; of which the Allier, the Loire, and the Yonne, are navigable. It now forms the de¬ partment of Nevers, which is alfo the name of the capi¬ tal city. NIWEGAL, N O A [ 3 Kiwegal NIWEGAL, a village lying on the coaft in Pem- ^ brokefhire. South Wales, remarkable only for the dif- ~ covery of an immenfe quantity of the flumps of trees appearing below low water mark, after and during a ftorm in the year 1590, notwithflanding the country all round is now entirely barren of wood. NIXAPA, a rich and confiderable town in New Spain, with a rich convent of Dominicans. The coun¬ try about it abounds in cochineal, indigo, and fugar. E. Long. 97. 15. N. Lat. 16. 42. NIZAM (fays Gibbon), one of the molt illuflrious minillers of the call, was honoured by the caliph as an oracle of religion and fcience 5 he was trufted by the iultan as the faithful vicegerent of his power and ju- flice. After an admin iff ration of 30 years, the fame of the vizier, his wealth, and even his fervices, were tranf- formed into crimes. He was overthrown by the in- fidious arts of a woman and a rival; and his fall was haflened by a rafh declaration, that his cap and ink horn, the badges of his office, were connected by the divine decree with the throne and diadem of the ful- tan. At the age of 93 years, the venerable ftatefman was’ difmiffed by his mailer, accufed by his enemies, and murdered by a fanatic : the lalt words of Nizam attefted his innocence, and the remainder of Malek’s life was fliort and inglorious. NO, (Jeremiah, Ezekiel), No-Ammon, (Nahum); a confiderable city of Egypt, thought to be the name of an idol which agrees with Jupiter Ammon. The ■Septuagint tranfiate the name in Ezekiel, Diofpolis, the city of Jupiter.” Bochart takes it to be Thebes of Egypt; which, according to Strabo and Ptolemy, was called Diofpolis. Jerome, after the Chaldee paraphraft Jonathan, fuppofes it to be Alexandria, named by wray of anticipation ; or an ancient city of that name is fup- pofed to have flood on the fpot where Alexandria was built. No-Man''s-Laru}, a fpace between the after part of tire belfrey and the fore part of a (hip’s boat, when the faid boat is flowed upon the booms, as in a deep waifl- ed veffel. Thefe booms are laid from the forecaflle nearly to the quarter-deck, where their after ends are ufually fuflained by a frame called the gallows, which confifts of two ftrong polls, about fix feet high, with a crofs piece reaching from one to the other, atlfcvart flaps, and ferving to fupport the ends of thofe booms, mails, and yards, which lie in referve to fupply the place of others carried away, &c. The fpace called JTo-Man's Land is ufed to contain any blocks, ropes, tackles, &c. which may be neceffary on the fore¬ caflle. It probably derives this name from its fitua- tion, as being neither on the flarboard nor larboard fide of the fhip, nor on the wafle or forecaflle ; but, being lituated in the middle, partakes equally of all thofe places. NOAH, or Noe, the fon of Lamech, was born in the year of the world 1036. Amidfl the general cor¬ ruption into which all mankind were fallen at this time, Noah alone w'as found to be jull and perfecl in his generation, walking with God (Gen. vi. 9.). This extraordinary perfon having therefore found fa¬ vour in the eyes of the Lord, and God feeing that all flefli had corrupted their ways, told Noah, that he was refolved to deflroy mankind from the face of the earth by a flood of waters; and not them alone, but all the 2 ] N O A beafls of the earth, and every creeping thing, as Well as the fowls of the air (Id. ib. >].). The Lord there¬ fore directed Noah, as a means of preferving him and his family (for he had three fons, Shem, Ham, and Japheth, who were all married before the flood), to build an ark or veffel of a certain form and fize fitted to that end, and which might befides accommodate fucli numbers of animals of all forts, that were liable to perifli in the flood, as would be fufficient to preferve the feveral fpecies, and again replenilh the earth ; to¬ gether with all neceffary provifions for them ; all which Noah performed, as may be leen more particularly un¬ der the article Ark. In the year of the -world 1656, and in the 600th year of his age, Noah, by God’s appointment, entered the ark, together with his wife, his three fons, their wives, and all the animals which God caufed to come to Noah; and being all entered, and the door of the ark being (hut upon the outfide, the waters of the deluge began to fall upon the earth, and increafed in fuch a manner, that they were fifteen cubits above the tops of the higheft mountains, and continued thus upon the earth for 150 days; fo that whatever had life upoti the earth, or in the air, was dellroyed, except fuch as were with Noah in the ark. But the Lord remember¬ ing (Noah, fent a wind upon the earth, which caufed the waters to fubfide; fo that upon the feventcenth day of the feventh month the ark refted on the mountains of Ararat ; and Noah having uncovered the roof of the ark, and obferving the earth was dry, he received or¬ ders from the Lord to come out of it, with all the ani¬ mals that were therein ; and this he did in the fix hun¬ dred and firft year of his age, on the 27th day of the lecond month. But the hiltory of the deluge is more circumilantially related already under the article De¬ luge. Then he offered as a burnt facrifice to the Lord one of all the pure animals that were in the ark ; and the Lord accepted his facrifice, and faid to him that he would no more pour oftt his curfe upon the whole earth, nor any more deftroy all the animals as he had now7 done. He gave Noah power over all the brute creation, and permitted him to eat of them, as of the herbs and fruits of the earth : except only the blood, the ufe of which God did not allow them. He bid him increafe and multiply, made a eovenant with him, and God engaged himfelf to fend no more an univerfal de¬ luge upon the earth ; and as a memorial of his promife, he fet his bow in the clouds, to be as a pledge of the covenant he made with Noah (Gen. ix.). Noah, being an hufbandman, began now to cult ivate the vine ; and having made wine and drank thereof, he unwarily made himfelf drunk, and fell afleepin his tent, and happened to uncover himfelf in an indecent p< (lure. Ham, the father of Canaan, having obferved him in this condition, made himfelf fport with him, and ac¬ quainted his two brothers with it, who were without. But they, inflead of making it a matter of fport, turm d awray from it, and going backwards they covered their father’s nakednefs, by throwing a mantle over him. Noah Awaking, and knowing what Ham had done, faid, that Canaan 1 the fon of Ham ffiould be accurfed, that he Ihould be a Have of flaves in refpeft of his brethren. It is thought he had a mind to (pare the perfon of his fon Ham, for fear the curfe might light upon N 0 A [3 Noah, upon the other children of Ham, who had no part in this aftion. He curfed Canaan by a fpirit of prophe¬ cy, becaufe the Canaanites his defcendants were after this to be rooted out by the Ifraelites. Noah added, Let the Lord, the God of Shem, be bleifed, and let Canaan be the fervant of Shem. And he was fo in effeft, in the perfon of the Canaanites fubdued by the Hebrews. Laftly, Noah faid, Let God extend the poffeffion of Japheth j let Japheth dwell in the tents of Shem, and let Canaan be his fervant. This pro¬ phecy had its accomplifliment, when the Grecians, and afterwards the Romans, being defcended from Japheth, made a conqueft of Afia, which was the portion of Shem. But Noah lived yet after the deluge three hundred and fifty years ; and the whole time of his life having been nine hundred and fifty years, he died in the year of the world 2006. He left three fons, Shem, Ham, and Japheth, of whom mention is made under their feveral names •, and, according to the common opinion, he divided the whole world amongit them, in order to repeople it. To Shem he gave Afia, to Ham Africa, and Europe to Japheth. Some will have it, that be¬ tides thefe three fons he had feveral others. The fpurious Berofus gives him thirty, called Titans, from the name of their mother Titsea. They pretend that the Teutons or Germans are derived from a fon of Noah called Thuifcon. The falfe Methodius alfo makes mention of Jonithus or Jonicus, a pretended fon of Noah. St Peter calls Noah a preacher of righteoufnefs (2 Peter ii. 5.), becaufe before the deluge he was in- ceffmtly preaching and declaring to men, not only by his difcourfes, but by his unblameable life, and by the building of the ark, in which he was employed fix fcore years, that the wrath of God was ready to pour upon them. But his preaching had no efTeft, fince when the deluge came, it found mankind plunged in their former enormities (Matt. xxiv. 37.). Several learned men have obferved, that the Hea¬ thens confounded Saturn, Deucalion, Ogyges, the god Coelus or Uranus, Janus, Proteus, Prometheus, &c. with Noah. The wife of Noah is called Noriah by the Gnoftics ; and the fable of Deucalion and his wife Pyrrha is manifellly invented from the hiftory of Noah. The Rabbins pretend, that God gave Noah and his fons (all who are not of the chofen race of Abra¬ ham they call Noachidas) certain general precepts, which contain, according to them, the natural right which is common to all men indifferently, and the obfervation of which alone will be fufficient to fave them. After the law of Mofes, the Hebrews would not fuffer any ftranger to dwell in their country, un- lefs he wmuld conform to the precepts of the Noachidse. In war they put to death, without quarter, all that were ignorant of them. Thefe precepts are feven in number. Theyfry? dire&s, that obedience be paid to judges, magiftrates, and princes. By the fecond, the worlhip of falfe gods, fuperftition, and facrilege, are abfolutely forbidden. The third forbids curfing the name of God, blaf- phemies, and falfe oaths. I hc fourt/i forbids all inceffuous and unlawful con- Vol. XV. Part I, 5 ] NOB junftions, as fodomy, heftiality, and crimes againft na- Noah ture. li . The Jlft-i forbids the effufion of blood of all forts of; animals, murder, wounds, and mutilations. The Jixt/i forbids thefts, cheats, lying, &c. The feventh forbids to eat the parts of an animal ftill alive, as was practifed by fome Pagans. To thefe the Rabbins have added fome others j but what inclines us to doubt the antiquity of thefe precepts is, that no mention is made of them in Scripture, or in the Avritings of Jofephus or Philo ; and that none of the ancient fathers knew any thing of them. NOB, a facerdotal city of the tribe of Benjamin or Ephraim. St Jerome fays, that in his time it was en¬ tirely dertroyed, and that the ruins of it might be feen not far from Diofpolis. When David was driven aAvay by Saul, he Avent to Nob, and alking the high prieft Ahimelech for fome provifions and arms, the prieft gave him the fhew bread Avhich had been lately taken off the holy table, and the fvvord of Goliath. Saul be¬ ing informed of this by Doeg, caufed all the priefts of Nob to be flain, and the city to be deftroyed, 1 Sam. xxi. xxii. NOBAH, a cityT beyond Jordan. It took the name of Nobah from an Ifraelite of this name Avho had made a conqueft of it, (Numb, xxxii. 42.). Gideon purfued the. Midianites as far as this city, (Judg. viii. 2.). Eu- febius fays, that there is a defolate place of this name about eight miles from Helhbon towards the fbuth. But this could not be the Nobah now mentioned, be¬ caufe it Avas much farther to the north. NOBILIARY, in literary hiftory, a book con¬ taining the hiftory of the noble families of a nation or province : fuch are Choriere’s Nobiliary of Dau- phine, and Caumartnrs Nobiliary of Provence. The Germans are faid to be particularly careful of their Nobiliaries, in order to keep up the dignity of their families. NOBILITY, in general, fignifies dignity, grandeur, or greatnefs } more particularly, it fignifies antiquity of family, joined Avith riches : in the common accepta¬ tion of the wrord, it means that quality or dignity which raifes a man above the rank of a peafant or a commoner. At a time Avhen the public mind is fo much agita¬ ted on this fubjeft, or fubjefts nearly allied to it, per¬ haps the lefs that is faid on it the better. We fhould therefore (as far as concerns the queftion about its ex¬ pediency in civil life, or the contrary ) moft cheerfully pafs it over in filence, did we not efteem it our duty to give our readers at leaft fome idea of it, and Avere it not our bufinefs to lay before them a feuv of thofe argu¬ ments Avhich of late have been fo copioufly retailed botli for and againft this illuftrious order of civil fociety : leaving them, however, that liberty Avhich every man unqueftionably ought to be allowed of judging for them- felves as they (hall fee moft proper. Whether that equality of rank and condition Avhich has of late been fo loudly contended for Avould be more agreeable to the order of nature, or more conducive to the happinefs and profperity of mankind, may in¬ deed be made a queftion \ but it is a queftion, Ave ap¬ prehend, which cannot receive different anfwers from men capable of reflecting Avithout prejudice and par¬ tiality. A ftate of perfeCt equality can fubfift only E among NOB [ 34 ] NOB among beings poileffing equal talents and equal vir¬ tues j but fuch beings are not men. Were all man¬ kind under the conftant influence of the laws of vir¬ tue, a diftinction of ranks would be unneceffary •, but in that cafe civil government itiell would likewife be unneceffary, becauie men would have attained all that perfedtion to which it is the objedt of civil govern¬ ment as well as of religion to guide them : every man then would be a law unto himfelf. But whillt, in fo many breads, the felfiih pafiions predominate over ihofe which are focial, violence mult be reitrained by authority •, and there can be no authority without a diftindtion of ranks, fuch as may influence the public opinion. It is well obferved by Hume, that government is founded only on opinion *, and that this opinion is of two kinds, opinion of intereft, and opinion of right. When a people are perfuaded that it is their intereft to fupport the government under which they live, that government muft be very liable. But among the worthlefs and unthinking part of the community, this perfuaficn has feldom place. All men, however, have a notion of rights—of a right to property and a right to power : and when the majority of a nation confl- ders a certain order of men as having a right to that eminence in which they are placed, this opinion, call it prejudice or what we will, contributes much to the peace and happinefs of civil fociety. There are many, however, who think otherwife, and imagine that “ the fociety in which the greatefl: equality prevails mull al¬ ways be the moll fecure. Thefe men conceive it to be the bufmefs of a good government to diilribute as equal¬ ly as poflible thofe bleflings which bounteous nature of¬ fers to all.” It may readily be allowed that this rea- foning is conclufive •, but the great queflion returns, “ How^/hrcan equality prevail in a fociety which is fecure ? and what is pqffible to be done in the equal diflribution of the bleflings of nature ?” Till thefe queftions be anfwered, we gain nothing by declaim¬ ing on the rights and equality of men 5 and the an- fwers which have fometimes been given to them fup- pofe a degree of perfection in human nature, which, if it were real, would make all civil inftitutions ufelefs, as well as the reveries of thofe reformers. The conduCl of the democratic Bates of Pagan antiquity, together with the oppreflive anarchy and flrameful violences which we have feen and Hill fee in a neighbouring kingdom, will be confidered by many as a full and fatisfaClory an- fwer, deduced from experience, to ail the fchemes of the vifionary theorift : fuch faCls at lead render the abo¬ lition of the order of nobility a matter of more impor¬ tance, and of infinitely greater difficulty, than thofe who plead for it are difpofed to allow. It is an opinion not uncommon, and at leaft plaufi- ble, that the nobility of a well regulated ftate is the beft fecurity again ft monarchical defpotifm or lawlefs usurpation on the one hand, and the confufion of de¬ mocratic infolence on the other. Self intereft is the mod powerful principle in the human breaft •, and it is obvioufly the intereft of fuch men to preferve that balance of power in fociety upon which the very ex- iftence of their order depends. Corrupted as the pre- fent age confeffedly is, a very recent inftance could be given, in which the Britilh Houfe of Peers refeued at once the fovereign and the people from the threatened Nobility, tyranny of a fadtious junto. As it is our bufinefs, how- —v— ever, to exhibit all opinions of any celebrity, we ihall lay before our readers a {hurt extradt from Dulaure’s Critical Hiftory of the French Nobility, which contains, in few but forcible words, fome of the common argu¬ ments againft this diftindtion of ranks. “ Nobility (fays he), a diiiindtion equally impo¬ litic and immoral, and worthy of the times of igno¬ rance and of rapine, which gave it birth, is a violation of the rights of that part of the nation that is depriv¬ ed of it} and as equality becomes aJlimu/us towards diltindlion, fo on the other hand this is the radical vice of a government and the fource of a variety of evils. It is almoft impoflible that there ftiould be any uncommon inftances of virtue in a ftate, when recom- penies belong exclufively to a certain clafs of fociety, and when it cofts them no more to obtain thefe than the trouble of being born. Amongft this lift of privi¬ leged perfons, virtues, talents, and genius, muft of courfe be much lefs frequent than in the other clafies, fince, without the pofleflion of any of thefe qualities, they who belong to it are ftill honoured and rewarded. Thofe who profit by this abfurd fubverfion of principles, and thofe who lofe by this unj&ft diftribution of favours, which feem to have grown into a right, cannot have any other than falfe, immoral, and pernicious ideas con¬ cerning merit.'1'’ A perfect equality, however, in rank and fortune has feldom been contended for, except by the moft ignorant enthufiafts. It is indeed doubtful whether it could poflibly exift. The more moderate and ra¬ tional reformers have acknowledged, that as thefe differ¬ ences have always exifted in fome way or other, fo, from the infinite variety of talents and attainments in the world, we have reafon to expert they will exift in every form of government and among every people. The queftion, therefore, is reduced to this: Whether the prefent mode of diftindtion, or any other which could be inftituted in its ftead, be upon the whole the beft ? That the prefent is not perfedl, or wholly with¬ out faults, few will be fanguine enough to contradidt : and a wife man in the lober hour of philofophical refledtion will fcarce prefume to affert, that any other fchetrte which human ingenuity can plan would be wholly without imperfedtion, or altogether free from error. The cafe is, the errors of our own fyftem are prefent, and on this account we fee and feel them with peculiar force: the other plan we look forward to perhaps in too fanguine a manner, and we probably forget, in the delufive heat of imagination, that if di- ftindtion depended entirely on merit, we ftiould fcarce find a fociety of men fo honeft, or fo able, as always to reward it according to its deferts 5 or if this were poflible, as perhaps in the nature of things it is not, i’uch is the felf-partiality of the generality of men, that few would think he were dealt juftly by if he were not promoted as well as his neighbour *, and it is clearly impoflible to promote every one. For fuch rtafons then, and many more which our limits oblige, us to omit, many think (and we are inclined to think with them), that it is fafer to remain as we are, as, we know the evils that attend our fituation, and are ftill able to bear them, rather than to hazard a change,. which, NOB [ 35 ] NOB Nobility, which, with fome benefits, might alfo perhaps increafe the troubles, and deftroy many of the pleafures of fo- cial life. Perhaps it may not be amifs to lay before our readers the following obfervations from that moft judi¬ cious commentator on the laws of England, Mr Jultice Blackftone, on this important fubjeft. „ “ The ditlin6lion of rank and honours (fays he) is Comment, neceffary in every well-governed Hate, in order to reward fuch as are eminent for their fervices to the public, in a manner the moll: defirable to individuals, and yet without burden to the community •, exciting thereby an ambitious, yet laudable ardour, and gene¬ rous emulation, in others. And emulation, or vir¬ tuous ambition, is a fpring of aflion which, however dangerous or invidious in a mere republic or under a defpotic fway, will certainly be attended with good effeifts under a free monarchy \ where, without deftroy- ing its exillence, its exceffes may be continually re- ftrained by that fuperior power from which all ho¬ nour is derived. Such a fpirit, when nationally dif- fufed, gives life and vigour to the community j it fets all the wheels of government in motion, which, under a wife regulator, may be. direcled to any beneficial purpofe \ and thereby every individual may be made fubfervient to the public good, while he principally means to promote his own particular views. A body of nobility is alfo more peculiarly necefifary in our mixed and compounded conftitution, in order to fup- port the rights of both the crown and the people, by forming a barrier to withftand the encroachments of both. It creates and preferves that gradual fcale of dignity, which proceeds from the peafant to the prince; rifing like a pyramid from a broad foundation, and diminilhing to a point as it rifes. It is this afcending and contracting proportion that adds liability to any government; for when the departure is fudden from one extreme to another, we may pronounce that Hate to be precarious. The nobility, therefore, are the pil¬ lars, which are reared from among the people, more immediately to fupport the throne ; and, if that falls, they mull alfo be buried under its ruins. Accordingly, when in the 17th century the commons had determined to extirpate monarchy, they alfo voted the houfe of lords to be ufelefs and dangerous. And fince titles of nobili¬ ty are thus expedient in the Hate, it is alfo expedient that their owners (hould form an independent and fe~ parate branch of the legifiature. If they were confound¬ ed with the mafs of the people, and like them had only a vote in eleCting reprefentatives, their privileges would foon be borne down and overwhelmed by the popular torrent, which would effedtually level all diftinCtions. It is therefore highly neceflary that the body of nobles {hould have a diftinCt aflembly, diltinCt deliberations, and dittinft powers from the commons.”-—Thefe re¬ marks, at a time like the prefent, deferve our ferious attention ; nor do we fuppofe our readers will be dif- pleafed, if we add the following obfervations on the fub- jeft from a periodical publication of long Handing and very confiderable merit. .Cent. Mug, “ Birth and nobility are a (tronger obligation to vir- vcl. xii. tue than is laid upon meaner perfons. A vicious or difhonourable nobleman is in effect perjured; for his honour is his oath. “ Under the patriarchal feheme, and at the firfl fet- ting out of the tribes, the heads of families had their particular efcutcheons, and their genealogies recorded with the utmoft exadtnefs : Even the Ancient of Bays confirmed this ; he often put his people in mind of the glory and virtues of their forefathers ; and hath fet a precedent for attainders, by vifiting the third and fourth generation. “ It is a vulgar error to fuppofe, that his bleffed Son chofe his followers out of the meaneft of the people, becaufe mechanics ; for this was part of the educa¬ tion of every Jewifh nobleman : Two of the number, being his kinfmen, were of the royal houfe of David ; one was a Roman gentleman, and another of the royal family of Syria ; and for the reft, he had the fame right of creation as his Father and his vicegerents, of advancing the poor to honour, and of exalting the lowly and meek. “ The ancient Greeks and Romans paid great regard to nobility ; but when the levelling principle obtained, and the people ftiared pofter and honour, thofe ftates foon dwindled and came to ruin. And in prefent Rome, great refpedt is paid to the renowned fami¬ lies of Colonna and Csefarini. In Venice, the notion of nobility is carried fo high as to become inconliftent with a republican feheme. The Spaniards pay more regard to their old nobles than to their old Chriftians ; and the French are but little behind them. What was faid of the duke of Montmorency by Henry IV. “ That he was a better gentleman than himfelf,” was, perhaps, the reafon why the laft heir of fo illuftrious a family was cut off, to make the houfe of Bourbon the firft in France.—The Welfh, Irifti, and Polanders, are remarkable for their attachment to blood and pe¬ digree. “ It is for the fake of the meaneft of our people, that the high value and regard for quality {hould be kept up ; for they are beft governed by thofe who feem form¬ ed for power : the robe of authority fits eafy upon them, and fubmiftion is as much our choice as our duty ; but upftarts prove the worft of tyrants. “ The ancient legifiators, who ftudied human nature, thought it advifeable, for the better government of ftates, that the people fhould be divided into the noble and the common. They judged it for the univerfal good of mankind, that the valiant and the wife {hould be fe- parated from the reft, and appointed for council and command. “ To this I take it that the inftitution of nobility is owing in all countries ; even thofe nations which we are pleafed to call favage, diftinguilh the wife and the valiant, obey them as counfellors and "commanders, which is placing them in the rank of nobles. “ Some, I know, look upon the inftitution of nobi¬ lity to be one of the groffeft impofitions upon the eom- mon fenfe of mankind ; they confine it indeed to he¬ reditary nobility ; they allow, that thofe who have done the commonwealth any fignal fervice {hould be diftinguifhed with honours, but. it feems an abfurdity to them that a man {hould be born a legitlator, as if wifdom or a knowledge of government ran in the blood. But if they would confider how ftrong the love of po- fterity is planted in human nature, they muft allow that nothing can be a ftronger motive to great and worthy aftions, than the notion that a man’s pofte- rity will reap the honour and profit of his labours. E 2 Befides, NobiiitVi NOB [ 36 ] NOB Nobility. Bdides, we are to fuppofe that men born to honours ancJ a hjgh fortune may be bred up in generous fenti- ments, and formed for the ftation they are to fill j that they muft be ftrangers to thofe vicious falfchoods and corruptions which neceflity firfi:, and then habit, puts men upon pra&ifing, whofe lives are fpent in purfuit of their fortunes. I will own, notv/itliHand¬ ing all thefe advantages, that many of them are like rocks whofe heads are in the clouds, but are fo barren that they are quite incapable of producing any thing j but in general, were their minds only upon a level with thofe of other men, we fhould expe£t better fruit from them. “ As authority is founded in opinion, all wife com¬ monwealths have been extremely jealous in keeping up the honour of their nobility. Wherever they be¬ come bafe, effeminate, cowardly, or fervile, their au¬ thority finks, they fall into contempt; then the people begin to confider them as ufelefs to government, and look upon their privileges as a grievance to fociety, and perhaps they think how to get rid of them, as happened in the commonwealth of Florence, where, after the expulfion of the duke of Athens, a petty tyrant of that city, many of the nobility having behaved fervilely to him, and infolently to the people, were degraded from the fenate and the magiftracy, and ren¬ dered incapable of holding any employment in the com¬ monwealth. “ Father Paul, the Venetian, fays, that you muft either keep your nobility free from taint, or have no nobility at all : That the high employments of the commonwealth fhould be beftowed amongft the moft ancient families, unlefs where a perfon ftiould diftin- guifh himfelf by fome fignal fervice to the ft ate. Such a man would think him'felf fufficiently rewarded by the honour of being out upon a footing with the ancient nobility *, and the nobility would be pleafcd to find that no commoner, except fome of great reputation and merit, was to hold any of the employments ufually poffeffed by their body. If the perfon fo preferred fhould not be rich enough to fupport the dignity of the office, the ftate may give him a penfion, but by no means fhould employments be made lucrative ; which not only ex- hauft and weaken the commonwealth, but wherever the high employments are fought for profit, the nobility lofe their generous fentiments, and it is a means of in¬ troducing corruption amongft them.” The origin of nobility in Fmrope is by fome referred to the Goths ; who, after they had feized a part of Europe, rewarded their captains with titles of honour, to diftinguifli them from the common people. We ft;all only in this place further confider the manner in which in our own country they may be created, and the incidents attending them ; referring for a fuller ac¬ count of their origin in Europe to the articles REVOLU¬ TION, and Civil Society. 1. The right of peerage feems to have been origi¬ nally territorial } that is, annexed to lands, honours, caftles, manors, and the like ; the proprietors and pofieffors of which were (in right of thofe eftates) allowed to be peers of the realm, and were fummoned to parliament to do fuit and fervice to their fovereign : and, when the land was alienated, the dignity palled with it as appendant. Thus in England the bifhops ft ill fit in the houfe of lords in right of fuccefTion to certain ancient baronies annexed, or fuppofed to be Nobility- annexed, to their epifcopal lands ; and thus in 11 v-—v-”' Henry VI. the poftefTion of the cattle of Arundel was adjudged to confer an earldom on its poffefibr. But afterwards, when Alienations grew to be frequent, the dignity of peerage was confined to the lineage of the party ennobled, and inftead of territorial became perfonal. Adtual proof of a tenure by barony became no longer neceflary to conftitute a lord of parliament j but the record of the writ of fummons to him or his anceftors was admitted as a fufEcient evidence of the tenure. Peers of Great Britain are now created either by writ or by patent; for thofe who claim by preferip- Comment* tion muft fuppofe either a writ or patent made to their anceftors 5 though by length of time it is loft. The creation by writ or the king’s letter is a fummons to attend the houfe of peers, by the ftyle and title of that barony which the king is pleafed to confer : that by- patent is a royal grant to a fubjedf of any dignity and degree of peerage. The creation by writ is the more ancient way 5 but a man is not ennobled thereby, unlefs he a&ually take his feat in the houfe of lords $ and fome are of opinion that there muft be at leaft tivo wrrits of fummons, and a fitting in two diftinft parlia¬ ments, to evidence a hereditary barony \ and there¬ fore the moft ufual, becaufe the fureft vmy, is to grant the. dignity by patent, which endures to a man and his heirs according to the limitation thereof, though he never himfelf makes ufe of it. Yet it is frequent to call up the eldeft fon of a peer to the houfe of lords by writ of fummons, in the name of his father’s baro¬ ny, becaufe in that cafe there is no danger of his chil¬ dren’s lofing the nobility in cafe be never takes his feat ; for they will fucceed to their grandfather. Crea¬ tion by writ has alfo one advantage over that by pa¬ tent ; for a perfon created by writ holds the dignity to him and his heirs, without any -words to that purport in the wrrit; but in letters patent there muft be words to diredl the inheritance, elfe the dignity endures only to the grantee for life. For a man or woman may be created noble for their own lives, and the dignity not defeend to their heirs at all, or defeend only to fome particular heirs : as where a peerage is limited to a man and the heirs male of his body by Elizabeth his preient lady, and not to fuch heirs by any former or fu¬ ture wife. 2. Let us next take a view of a few of the principal incidents attending the nobility,—exclufive of their capacity as members of parliament, and as heredi¬ tary eounfellors of the crown j for both which we refer to the articles Lords and Parliament. And firft we muft obferve, that in criminal cafes a noble¬ man fhall be tried by his peers. The great are al¬ ways obnoxious to popular envy : were they to be judged by the people, they might be in danger from the prejudices of their judges ; and would moreover be deprived of the privilege of the meaneft fubjefts, that of being tried by their equals, which is fecured to all the realm by magna charta, c. 29. It is faid, that this does not extend to bilhops, who, though they are lords of parliament, and fit there by virtue of their baronies which they hold /are ecclefice, yet are not en¬ nobled in blood, and confequently not peers with the nobility. As to peereffes, no provifion was made for their NOB [ 37 ] NOB Nobility, their trial when accufed of treafon or felony, till after “—V Eleanor duehefs of Gloucefter, wife to the lord pro¬ testor, had been accufed of treafon, and found guilty of witchcraft, in an ecclefiaftical fynod, through the intrigues of Cardinal Beaufort. This very extraordi¬ nary trial gave oceafion to a fpecial ftatute, 20 Hen. VI. c. 9. which enacts, that peerefles, either in their own right or by marriage, fhall be tried before the fame judicature as peers of the realm. If a woman, noble in her own right, marries a commoner, Ihe Hill re¬ mains noble, and ft)all be tried by her peers : but if ftie be only noble by marriage, then by a fecond mar¬ riage with a commoner ftie lofes her dignity 5 for as by marriage it is gained, by marriage it is alfo loft. V et if a duchefs dowager marries a baron, fhe continues a duchefs ftill: for all the nobility are pares, and there¬ fore it is no degradation. A peer or peerefs (either in her own right or by marriage) cannot be arretted in civil cafes: and they have alfo many peculiar privileges annexed to their peerage in the courfe of judicial pro¬ ceedings. A peer fitting in judgment, gives not his verdidt upon oath, like an ordinary juryman, but upon his honour^ he anfwers alfo to bills in chancery upon his honour, and not upon his oath : but, when he is examined as a witnefs either in civil or criminal cafes, lie muft be fworn; for the refpedt which the law' ftrows to the honour of a peer does not extend fo far as to overturn a fettled maxim, that in judicio non creditur nijijuratus. The honour of peers is however fo high¬ ly tendered by the law, that it is much more penal to fpread falfe reports of them, and certain other great of¬ ficers of the realm, than of other men : fcandal againft them being called by the peculiar name of fcandulnm tnagnatum, and fubjedted to peculiar puniihment by divers ancient ftatutes. A peer cannot lofe his nobility but by death or at¬ tainder } though there was an inftance, in the reign of Edward IV. of the degradation of George Nevile duke of Bedford by adl of parliament, on account of his poverty, which rendered him unable to fupport his dignity. But this is a Angular inftance, which ferves at the fame time, by having happened, to (how the power of parliament} and, by having happened but once, to (how how tender the parliament hath been in exerting fo high a power. It hath been faid in¬ deed, that if a baron waftes his eftate, fo that he is not able to fupport the degree, the king may degrade him: but it is exprefsly held by later authorities, that a peer cannot be degraded but by a£t of parliament. Anton. Matthaeus obferves, that nobility, among the Romans, was a quite different thing from what it is among us. The nobles, among the Romans, were either thofe raifcd to the magiftrature, or defcended from magiftrates: there was no fuch thing as nobility by patent. Bartoli fays, that dodlors, after they have held a pro- feffor’s chair in an univerfity for 20 years, become noble 5 and are entitled to all the rights of counts. But this claim is not admitted at court, &c. though Bartoli’s fentiments be backed with thofe of feveral other authors, particularly Chaffanseus in his Confueta- din. Burgundies ; Boyer fur la Coutume de Berry ; Faber C. de Dig. Def. 9. &c. which laft, however, reftrains Bartoli’s rule to doflors in law, and princes phyficians. By an edi£t of the French king in 1669, it is de- 3 dared, that trade (hall not derogate from nobility, pro- Nobility, vided the perfon do not fell by retail. Nobie. In Bretagne, by ancient cuftom, a nobleman lofes " v "* nothing by trading even in retail ; but he reaffumes all his rights as foon as he ceafes traffic, his nobility having flept all the time. In Germany, a woman, not noble by birth, doth not become, v. gr. a countefs or baronefs by marrying a count or baron : a lady of the higher degree indeed be¬ comes a princefs by marrying a prince } but this does not hold of a lady of the lower nobility. On the coaft of Malabar, children are only capable of being noble by the mother’s fide } it being allowed them to take as many hulbands as they pleafe, and to quit them whenever they think proper. NOBLE, Nobiiis, a perfon who has a privilege which raifes him above a commoner or peafant, either by birth, by office, or by patent from his prince. The word comes from the Latin nobilis; formed from the ancient nofeibilis, “ diftinguil'hable, remarkable.” In England, the word noble is of a narrower import than in other countries, being confined to perfons above the degree of knights} whereas, abroad, it com¬ prehends not only knights, but what we (imply call gentlemen. The nobles of England are alfo called pares regni, as being nobilitatis pares, though gradu impares. The Venetian noblejfe is famous: it is in this that the fovereignty of the ftate refides. It is divided into three claffes. The firft only comprehends 24 families. The fecond includes the defeendants of all thofe who were entered in the Golden Book, in 1289, and deftined to govern the ftate, which then began to be ariftocratic. The third confifts of fuch as have bought the dignity of noble Venetians. This laft clafs is only .admitted to the inferior employs} the two former to all indiffer¬ ently. The title of noble Venetians is fometimes alfo given to foreign kings, princes, &c. Nobles, among the Romans, were fuch as had the jus imaginum, or the right of ufing the pictures or ftatues of their anceftors } a right which was allowed only to thofe whofe anceftors had borne feme curule office, that is, had been curule cedile, cenfor, preetor, or conful. For a long time, none but the patricii were the nobiles, becaufe no perfon but of that fuperior rank could bear any curulc office } hence in Livy, Salluft, &c. nobilitas is ufed to fignify the patrician order, and fo oppofed to plebs. To make the true meaning of nobiles ftill more clear, let it be obferved, that the Ro¬ man people were divided into nobiles, novi, and ignobiles. Nobiles were they who had the pidlures, &c. of their anceftors } novi were fuch as had only their own } igno¬ biles wrere fuch as had neither. See Jus Imaginis. The Roman nobility, by wray of diftindtion, wore a half moon upon their ffioes, efpecially thofe of pa¬ trician rank. The Grecian nobility were called EvTrxlgidai, as being defcended from thofe old heroic anceftors fo famous in hiftory. Such W'ere the Praxiergidee, Eirobutidcc, Alc- mceonidce, &c. all which had many privileges annexed to their quality } amongft which was this, that they wore gralhoppers in their hair as a badge of nobility. Noble, a money of account containing fix (hillings and eight pence. The noble was anciently a real coin ftruck in the reign of Edward III. and then called the penny of gold;. but. N O C [ 38 ] N O C Nobk but it was afterwards called a r of e-noble ^ from its being AT H ftamped with a rofe : it was current at 6s. 8d. buii.m* NOCERA, a town in Italy, in the dominions of —the king of Naples and Sicily, or, as he is more com¬ monly called, the king of the Two Sicilies. It is an epifcopal city, but might with greater propriety be ftyled a duller of villages 5 its feveral parts being ex¬ tended along the foot of the mountains, from the Citta Sotana, or low town-, and the bilhop’s palace, together with fome convents embowered in cyprefs groves, cover the peak of a fingle hill in a very pic- turefque manner, and compofe the Citta Soprana. Nocera (a), it is reported, contains near 30,000 in¬ habitants -, they are difperfed in forty patches of habi¬ tation. Their houfes are conftruded of two kinds of Hone: the common walls are built with yellow tufa dug out of the hills that lie about a mile to the ealt of the town ; which ftone feems unqueftionably to have been formed by a confolidation of fubftances thrown out of Vefuvius, becaufe, on opening thefe quarries, the workmen have frequently difeovered tombs, vafes, and coins locked up in the body of the ftony ftratum. The cafes of their doors and windows are made of a black ftone drawn from the hill of Fiano, two miles to the north : it lies eight feet below the furface, in a bed or vein 140 feet thick, refting upon a bafe of fand. This feems evidently to be a ftream of lava congealed. Nocera is a place of very confiderable antiquity : in the 13th century it was called de Pagani, to diftinguilh it from a city in Umbria of a fimilar name 5 this addi¬ tion was in allufion to a colony of Saracens which Fre¬ derick of Suabia brought from Sicily, and fettled here, that they might be out of the way of their dangerous connexions with Africa: hence Nocera has often been confounded with Lucera by the negligent or ignorant chroniclers of the fucceeding ages. The moft remark¬ able event that occurs in its hiftory is the fiege of its caftle, A. D. 1384. E. Long. 12. 49. N. Lat. 43. 1. Terra NOCEIUJNA, Earth of Nocera, in the Materia Medica, a fpecies of bole, remarkably heavy, of a gray- ilh-white colour, of an infipid tafte, and generally with fome particles in it which grit between the teeth. It is much efteemed by the Italians as a remedy for venom¬ ous bites, and in fevers; but, excepting as an abforbent und aftringent, no dependence is to be had on it. NOCTAMBULI, Noctambulones, or Night- walkers ; a term of equal import with fomnambuli, applied to perfons who have a habit of riling and walking about in their deep. The word is a com¬ pound of the Latin nox, “ night,” and ambulo, “ I walk.” Schenkius, Plorftius, Clauderus, and Hildanus, who have written of deep, give us divers unhappy hiftories of fuch no&ambuli. When the difeafe is moderate, the perfons aftefled with it only repeat the aftions of the day on getting out of bed, and go quietly to the places they frequented at other times ; but thofe who have it in the moft violent degree, go up to dangerous places, and do things which would terrify them to No&am- think of when they are awake. Thefe are by fome buli called lunatic night-walkers, becaufe fits are obferved y0io^nVJ, to return with the moft frequency and violence at the ■ ° “-"a' changes of the moon.—For the cure fome recommend purging and a cooling regimen : others are of opinion that the belt method is to place a velfel of water at the patient’s bedfide in fuch a manner that he will na¬ turally ftep into it when he gets out of bed 5 or if that Ihould fail, a perfon Ihould fit up to watch and beat him every time it happens. See Sleep-walkers, or Som- NAMBULI. NOCTILUCA, a fpecies of phofphorus, fo called becaufe it Ihines in the dark without any light being thrown upon it. NOCTURNAL, fomething relating to the night, in contradiftimftion to diurnal. Nocturnal, NoElurlabium, an inftrument chiedy ufed at fea, to take the altitude or depreffion of fome ftars about the pole, in order to find the latitude and hour of the night. Some nocturnals are hemifpheres, or planifpheres, on the plane of the equinoctial. Thofe commonly in ufe among feamen are two 5 the one adapted to the’polar ftar, and the firft of the guards of the Little Bear j the other to the pole ftar, and the pointers of the Great Bear. This inftrument confifts of two circular plates, ap¬ plied to each other. The greater, which has a handle to hold the inftrument, is about 2I7 inches diameter, and is divided into twelve parts, agreeing to the twelve months -, and each month fubdivided into every fifth day 5 and fo as that the middle of the handle corre- fponds to that day of the year, wherein the ftar here re¬ garded has the fame right afeenfion with the fun. If the. inftrument be fitted for two ftars, the handle is made moveable. The upper left circle is divided into twenty-four equal parts for the twenty-fours of the day, and each hour fubdivided into quarters. Thefe twenty- four hours are noted by twenty-four teeth to be told in the night. Thofe at the hour 1 2 are diftinguifhed by their length. In the centre of the two circular plates ^ f is adjufted a long index, moveable upon the upper plate4 ccCLX'c and the three pieces, viz. the two circles and index, are joined by a rivet which is pierced through the centre with a hole, through which the ftar is to be obferved. To ufe the nofturnal, turn the upper plate till the long tooth, marked 12, be againft the day of the month on the under plate ; then, bringing the inftrument near the eye, fufpend it by the handle with the plane nearly parallel to the equinoftial, and viewing the pole ftar through the hole of the centre, turn the index about, till, by the edge coming from the centre, you fee the bright ftar or guard of the Little Bear, (if the in¬ ftrument be fitted to that ftar) : then that tooth of the upper circle, under the edge of the index, is at the hour of the night on the edge of the hour circle, which may be known without a light, by counting the teeth from the longeft, which is for the hour 12. , NOB, (a) Anciently, Nuceria Alphaterna, a word of unknown etymology. It was a Roman colony, and had its mint, Num. Nucerin. I. Caput virile imberbe.—Equus ftans capite reflexo inter crura. A . . IN , . OLIVE PRESS PLATE CCCLXX. NODE S BB-AMIPf’S observatory NOD C 39 ] N O L NOD, or the Land of NOD. It was to this country now LP, or any part LS, reprefent the excels of the that Cain withdrew after his fratricide, (Gen. iv. 16.). fun’s aftion at T ; and this being refolved into the The Septuagint, as well as Jofephus, read Naid inftead of Nod, and have taken it for the name of a place. It is not eafily known what country this was, unlefs per¬ haps it was the country of Nyfe or Nyfea, towards Hvrcania. St Jerome and the Chaldee interpreters have taken the word Nod in'the fenfe of an appella¬ tive, for vagabond ox fugitive ; “ He dwelt a fugitive in the land.” But the Hebrew reads, “ He dwelt in the land of Nod,” (Gen. iv. 16.). NODAB, a country bordering upon Iturea and Idumcea, but now unknown. We read in the Chro¬ nicles, that the tribe of Reuben, aHifted by thofe of Gad and Manafleh, had a war againft the Hagarites, the Jeturites, and the people of Nephifh, and of Nodab, in which the Ifraelites had the advantage (l Chr. v. 19.). But the time and the other particulars of this rvar are unknown. NODATED HYPERBOLA, a name given by Sir Ifaac Newton to a kind of hyperbola, which, by turn¬ ing round, decuflates or erodes itfelf. NODDY. See Sterna, Ornithology Index. NODE, a tumor arifing on the bones, and ufually proceeding from fome venereal caufe ; being much the lame with what is otherwife called exojlofs. NODES, in Aflronomy, the two points where the orbit of a planet interfefls the ecliptic. Plate Such are the two points C and D, fig. I. of which CCCLXX. t|ie no(Je C, where the planet afeends northward above '‘S- the plane of the ecliptic, is called the afeending node, or the dragon’s head, and is marked thus fp. The other node D, where the planet defeends to the fouth, is called the defeending node, or the dragon's tail, marked thus TS • The line CD, wherein the two circles CEDE and CGDH interfedl,. is called the line of nodes. It ap¬ pears from obfervation, that the line of the nodes of all the planets conflantly changes its place, and drifts its fituation from eaft to weft, contrary to the order of the figns ; and that the line of the moon’s nodes, by a retrograde motion, finifhes its circulation in the compafs of 19 years ; after which time, either of the nodes having receded from any point of the ecliptic, returns to the fame again ; and when the moon is in the node, (he is alfo feen in the ecliptic. If the line of nodes were immoveable, that is, if it had no other motion than that whereby it is carried round the fun, it would ahvays look to the fame point of the ecliptic, or would keep parallel to itfelf, as the axis of the earth does. From what hath been faid, it is evident, that the moon can never be obferved precifely in the ecliptic, but twice in every period *, that is, w^hen (he enters the nodes. When flic is at her greateft diftance from the nodes, viz. in the points E, F, Ihe is faid to be in her limits. The moon muft be in or near one of the nodes, when there is an eclipfe of the fun or moon. To make the foregoing account of the motion of the moon’s nodes ftill clearer, let the plane of fig. 2. re¬ prefent that of the ecliptic, S the fun, T the centre of the earth, L the moon in her orbit DN d n. N« is live line of the nodes palling between the quadrature Q, and the moon’s place L, in her laft quarter. Let 4< force LR, perpendicular to the plane of the moon’s i orbit, and PR parallel to it, it is the former only that has any effedl to alter the pofition of the orbit, and in this it is wholly exerted. Its effedl is twofold : 1. It diminilhes its inclination by a motion which we may conceive as performed round the diameter D d, to which LT is perpendicular. 2. Being compounded with the moon’s tangential motion at L, it gives it an intermediate diredlion Lr, through which and the centre a plane being drawn, muft meet the ecliptic nearer the conjunction C than before. NODUS, or Node, in Dialling, a certain point or pole in the gnomon of a dial, by the fliadow or light whereof either the hour of the day in dials without fur¬ niture, or the parallels of the fun’s declination, and his place in the ecliptic, &c. in dials with furniture are Ihown. See Dialling. NOEOMAGUS lexuviorum, (Ptol.) *, thought to be the Civitas Lexoviorum of the lower age. Now Lifieux, a city in Normandy.—Another of the Trica- fini; a town of Gallia Narbonenfis ; thought to be S. Pol. de Trois Chateaux, fix miles to the weft of Nyons in Dauphine. NOETIANS, in church hiftory, Chriftian heretics in the third century, followers of Noetius, a philofopher of Ephefus, who pretended that he was another Mofes font by God, and that his brother was a new Aaron. His herefy confifted in affirming that there was but one perfon in the Godhead j and that the Word and the Holy Spirit were but external denominations given to God in confequence of different operations : that, as Creator, he is called Father ; as Incarnate, Son ; and as defeending on the apoftles, Holy Ghof. NOLA, a very ancient city, formerly populous and ftrong, fituated in a plain to the north-eaft of Vefuvius, in Campania, faid to be built by the Chalcidians j (Juftin, Silius Italicus) ; according to others, by the Tufcans. At this place Hannibal met with the firit check by Marcellus. Vefpafian added the appellation Augufa Colonia, (Frontinus). At this place, or in its neighbourhood, Auguftus is faid to have expired. It is alfo faid that bells were firft invented there in the be¬ ginning of the 5th century ; hence their Latin names No/ce or Campance. It retains its old name to this day, but it hath vaftly fallen ftiort of its ancient fplendour. A town of the kingdom of Naples. E. Long. if. N. Lat. 41. 5. NO LANA, a genus of plants belonging to the pent- andria clafsj and in the natural method ranking under the 41ft order, Afperifolice. See Botany Index. NOLLE prosequi, is where a plaintiff in an ac¬ tion does not declare in a reafonable time ; in which cafe it is ufual for the defendant’s attorney to enter a rule for the plaintiff to declare, after which a non prof. may be entered. A nolle profequi is efteemed a volun¬ tary confeflion, that the plaintiff has no caufe of aftion j and therefore if a plaintiff enters his nolle profeqm, he ftiall be amerced ; and if an informer caufe the fame to be entered, the defendant (hall have cofts. NOLLET, Jean Antoine, a deacon, licentiate in theology, preceptor to the Enfans de France for phy- fics and natural hiftory, regius profeffor of phyfics in- the college, of Navarre, member of the Academy of. Sciences Nodes II Nollet. N O L [ 40 ] N 0 M Nollet. Sciences at Paris, of the Royal Society of London, of —"v—the Inftitution of Bologna, and of the Academy of Sciences of Erfort •, was born at Pimbre, in the diocefe of Noyon, on the 17th of November 1700, of refpedt- able but not -wealthy parents. To make up the want of riches, they determined to give their fon a good edu¬ cation. They fent him to the college of Clermont in Beauvoifis, and afterwards to Beauvais, there to finifh his introduftory ftudies. The progrefs which he made in the different claffes, determined them to fend him to lludy philofophy at Paris. Thenceforward they intend¬ ed him for the clerical order *, and they confidered the ftrktnefs and purity of his morals, together with his un¬ wearied application to ftudy, as fufficient proofs of his vocation. The young Nollet yielded without reluct¬ ance to the withes of his parents. As foon as he was capable of ihowing an inclination for any thing, he had difcovered a tafle for phyfics •, but this was not become his ruling paflion •, he therefore facrinced it to the ftudy of fcholaftic divinity, to which he wholly dedicated himfelf during his time of probation in 1728. No fooner had he been invefted wuth the deaconfhip, than he folicited and obtained a licence to preach. This new occupation, however, did not make him entirely lofe light of thofe ftudies which had firft engaged his atten¬ tion. They infenfibly began to occupy a greater por¬ tion of his time, which was now more equally divided between theology and the fciences. The latter, how¬ ever, prevailed ; and thenceforth he entered into the ftudy of phyftcs with an ardour which was only increaf- ed by that kind of privation to which he had been long fubjeft. He was received into the Society of Arts, eftablilhed at Paris under the patronage of the late count de Clermont. In 1730, the abbe Nollet was en¬ gaged in a work conjunftly with Reaumur and du Fay of the Academy of Sciences. In 1734, he went to London in cornpany with M. M. du Fay, du Hamel, and de Juflieu. His merit procured him a place in the Royal Society without any folicitation. Tavo years af¬ ter, he went to Holland, where he formed an intimate connexion with Defaguliers, Gravefande, and Mufch- enbroeck. On his return to Paris, he reftimed the courfe of experimental phyfics which he had begun in 1735, and which he continued till 1760. Thefe courfes of phyfics firft fuggefted the idea of particular courfes in other bratiches of fcience, fuch as in che- miftry, anatomy, natural hiftory, &c. In 173^5 ^ie count de Maurcpas prevailed on the cardinal Fleury to eftablifh a public clafs for experimental phyfics •, and the abbe Noll’et was appointed the firft profeffor. In the beginning of the year 1739, he -was admitted a member of the Royal Academy of Sciences ; and in the month of April following, the king of Sardinia intend¬ ing to eftablilh a profefforfliip of phyfics at Turin, in¬ vited the abbe Nollet into his dominions. From thence he travelled into Italy. In 1744, he was honoured with an invitation to Verfailles, to inftrudl the dauphin in experimental philofophy ; the king and royal family were often prefent at his ledlures. The qualities as well of his underftanding as of his heart gained him the efteem and confidence of his pupil. Going one day in ftate to Paris, he caufed intimation to be made that he was to dine at the Thuilleries. M. Nollet having gone thither to pay his court, the dauphin no fooner perceiv¬ ed him, than he had the goodnefs to fay, “ Binet has the advantage of me, he has been at your houfe.” Till Nollet, the period of his death, this prince ftrowed marks of the ftrongeft attachment and favour for this ingenious phi- v lofopher. He would have wilhed that he had been a little more attentive to the improvement of his fortune. He prevailed upon him to go and pay court to a man in power, whofe patronage might have been of fervice to him. The abbe Nollet accordingly waited upon the placeman, and made him a prefent of his works. “ I never read any works of that kind,” faid the patron coldly, and calling a look at the volumes before him. “ Sir (replied the abbe), will you allow them to remain in your antichamber i1 There perhaps there may be found men of genius who will read them with pleafure.” In the month of April I749> he made a grand tour in¬ to Italy, being fent thither for the purpole of making obfervations. At Turin, Venice, and Bologna, the abbe Nollet appeared as a deputy from the philofophers of the reft of Europe. During his Ihort ftay in Italy, the rvonders of eledlricity Avere not the only objedt of his refearches ; every part of phyfics, the arts, agricul¬ ture, &c. came equally under his notice. Upon his return through Turin, the king of Sardinia, ahvays truly fenfible of bis merit, offered him the order of Saint Maurice, which he did not think proper to ac¬ cept Avithout his fovereign’s permiflion. In 17.53 the king inftituted a clafs of experimental philofophy in the royal college of Navarre, and appointed the abbe Nollet profeffor. In 1757, he received from the king a brevet appointing him preceptor in phyfics and natu¬ ral hiftory to the Enfans de Fi'ance. In the month of Auguft, the fame year, he Avas appointed profeflor of experimental philofophy in the fchool of artillery, at that time eftabliftied at la Fere. In the month of No¬ vember following, he Avas admitted as a penfionary of the Royal Academy of Sciences. M. de Cremillo, di- re&or general of artillery and fortification, having founded a clafs of experimental philofophy at Mezieres in 1761, the abbd Nollet Avas appointed profeffor. This celebrated and laborious philofopher, Avho has rendered the moft important fervices to phyfics by the difeoveries Avith which he has enriched every branch of this feicnce, but particularly eleflricity, died at Paris on the 25th of April 1 770, aged 70 •, much regretted by the lite¬ rary Avorld, and by his friends, of Avhom his gentle cha- rafier and beneficent heart had procured him a great number. He often retired from the gay and fplendid focieties of Paris, to gNe affiftance to his relations, Avho Avere by no means in affluent circumftanees. His Avorks are, 1. Several papers inferted in the memoirs of the A- cademy of Sciences; among Avhich one on the Hearing of Filhes is particularly valuable. 2. Lefotis de Ehj‘ Jique Experimentale, 6 vols 12mo *, a book Avell com- pofed, and uniting pleafure Avith inftru£lion. 3. Recueil de Lettres fur REle&ricite, 3 vols I2mo, 1753. 4. Ef-* fai fur I'EleBricite des corps, 1 vol. 12mo. 5. Recherches fur les caufes particulieres des Rhcnonienes Eleciriques, I vol. i2mo. 6. DAndes experiences, 3 vols i2mo, with figures, I77°* NOMADES, a name given, in antiquity, to feveral nations, Avhofe Avhole occupation Avas to feed and tend their flocks *, and Avho had no fixed place of abode, but Avere conftantly fhifting, according to the conveniences of pafturage.—The word comes from the Greek pafco, “ I feed.” The N O M [ 41 ]' N O M Nomades The moft celebrated among the Nomades were thofe II of Africa, who inhabited between Africa properly fo Nommals. ca]jec^ j_0 t]ie eafl^ anc^ Mauritania to the weft. They are alfo called Numiclce or Numidians.—Salluft fays, they were a colony of Perftans brought into Africa with Hercules. The Nomades of Afia inhabited the coafts of the Caf- pian fea. The Nomades of Scythia were the inhabi¬ tants of Little Tartary 5 who ftill retain the ancient manner of living. NO MARCH A,, in antiquity, the governor or com¬ mander of a nome or nomog.—Egypt was anciently di¬ vided into, feveral regions or quarters, called names, from the Greek >«««?, taken in the fenfe of a divifion ; and the officer who had the adminiftration of each name or nomos, from the king, was called nomarcha, from and “ command.” NOMBRE-de-dios, a town of Mexico, in the pro¬ vince of Darien, a little to the eaftward of Porto-Bello. It was formerly a famous place *, but it is now abandon¬ ed, on account of its unhealthy fituation. W. Long. 78. 35. N. Lat. 9. 43. NOMBRIL point, in Heraldry, is the next below the fefs point, or the very centre of the efeuteheon. Suppofing the efcutcheon divided into two equal parts below the fefs, the firft of thefe divifions is the nombril, . and the lower the bafe. NOME, or Name, in. Algebra, denotes any quan¬ tity with a fign prefixed or added to it, whereby it is connedled with fome other quantity, upon which the whole becomes a binomial, trinomial, or the like. See Algebra. NOMENCL ATOR, in Roman antiquity, was ufual- ly a flave who attended upon perfons that flood candi¬ dates for offices, and prompted or fuggefted to them the names of all the citizens they met, that they might court them and call them by their names, which among that people was the higheft piece of civility. NomencLators, among botanical authors, are thofe who have employed their labours about fettling and ad- jufting the right names, fynonymes, and etymologies of names, in regard to the whole vegetable world. NOMENCLATURE, NoMENCEATURA,acatalogue of feveral of the more ufual words in any language, with their fignifications, compiled in order to facilitate the ufe of fuch words to thofe who are to learn the tongue : luch are our Latin, Greek, French* &c. nomencla¬ tures : Or a fyftem of technical language by which the objeds of any fcience are denoted, as, for inftance, the prefent language of chemical fcience, ufually called the new chemical nomenclature, from its recent conftruftion. NOMENEY, a town in Germany, in the duchy of Lorrain, fituated on the river Seille, 15 miles north of Nancy. NOMINALS, or Nominalists, a fe& of fchool philofophers, the difciples and followers of Occam, or Ocham, an Engliffi Cordelier, in the 14th century. They were great dealers in words, whence they were vulgarly denominated 1^0^-/^//^; but had the deno¬ mination of Nominalijls, becaufe, in oppofition to the RealiJIs, they maintained, that words, and not things, were the objeft of diale&ics. This feft had its firft rife towards the end of the nth century, and pretended to follow Porphyry and Ari- Vol XV. Part I. ftotle; but it wras not till Ocham’s time that they bore Nominal^ . the name. The chief of this feet, in the nth century, Nomina- was a perfon called John, who, on account of his logi- , mc' . cal fubtility, was called the fophijl; and his principal difciples were Robert of Paris, Rofcelin of Compiegne, and Arnoul of Laon. At the beginning, the Nominals. had the upper hand : but the Realifts, though greatly divided among themfelves, were fupported by men of great abilities fuch as Albertus Magnus, T. Aquinas, and Duns Scotus. The nominal fe£t came hereby in¬ to difrepute 5 till William Occam, in the 14th century, again revived it, and filled France and Germany with the flame of difputation. Having joined the party of the Francifcan monks, who ftrenuoufty oppofed John XXII. that pope himfelf, and his fucceftbrs after him, left no means untried to extirpate the philofophy of the Nomi- nalifts, which was deemed highly prejudicial to the in- terefts of the church : and hence it was, that, in the year 1339, the univerfity of Paris, by a public edift, folemnly condemned and prohibited the philofophy of Occam, which was that of the Nominalifts. The con- fequence was, that the Nominalifts flouriftred more than ever. In the 15th century, the controverfy was conti¬ nued with more vigour and animofity than before ; and the difputants were not content with ufing merely the force of eloquence, but had frequently recourfe to more hoftile and dangerous weapons ; and battles ivere the confequence of a philofuphical queftion, which neither fide underftood. In moft places, however, the Realifts maintained a manifeft fuperiority over the Nominalifts. While the famous Gerfon, and the moft eminent of his difciples were living, the Nominalifts were in high efteem and credit in the univerfity of Paris. But upon the death of thefe patrons, the face of things was much changed to their difadvantage. In the year 1473, Louis XL by the inftigation of his confefibr, the biffiop of Avranches, iffued out a fevere edidl againft the doc¬ trines of the Nominalifts, and ordered all their writings to be feized and fecured, that they might not be read by the people : but the fame monarch mitigated this edi (viz. thofe which only con¬ cern the confeffion of the true Chriftian faith, and the doftrine of the facraments), with an exprefs exception of thofe relating to the government and powers of the church, and to infant baptifm. And by flat. 10 Ann. c. 2. this toleration is ratified and confirmed j and it is declared, that the faid aft fhall at all times be inviola¬ bly obferved for the exempting fuch Proteftant diilent- ers as are thereby intended from the pains and penalties therein mentioned. 1 hus, though the offence of non¬ conformity is by no means univerfally abrogated, it is fufpended, and ceafes to exift with regard to thefe Pro¬ teftant diffenters, during their compliance wfith the con¬ ditions impofed by the aft of toleration : and, under thefe conditions, all perfons, who will approve them- felves no Papifts or oppugners of the Trinity, are left at full liberty to aft as their confeiences fhall direct them in the matter of religious worfhip. And if any perfon ftiall wilfully, malieioufly, or contemptuoufly di- flurb any congregation, affembled in any church or per¬ mitted meeting-houfe, or fhall mifufe any preacher or teacher there, he (hall (by virtue of the fame ftatute) be bound over to the feffions of the peace, and for¬ feit 20I. But by ftatute 5 Geo. I. c. 4. no mayor or principal magiftrate muft appear at any diffenting meet¬ ing with the enfigns of his office, on pain of difability to hold that or any other office : the legiflature judging it a matter of propriety, that a mode of worfhip, fee up in oppofition to the nation, when allowed to be exer- cifed in peace, ffiould be exercifed alfo with decency, gratitude, and humility. Neither doth the aft of tole¬ ration extend to enervate thofe claufes of the ftatutes 13 & 14 Car. II. c. 4. and 17 Car. II. c. 2. which pro¬ hibit (upon pain of fine and imprifonment) all perfons from teaching fchool, unlefs they be licenfed by the ordinary, and fubferibe a declaration of conformity to the liturgy of the church, and reverently frequent di¬ vine fervice ejlablifhed by the laws of this kingdom. “ As to Papijls what has been faid of the Proteftant diffenters would hold equally ftrong for a general tole¬ ration of them ■, provided their feparation was founded only upon difference of opinion in religion, and their principles did not alfo extend to a fubverfion of the civil government. If once they could be brought to renounce the fupremacy of the Pope, they might quietly enjoy their feven facraments; their purgatory, and auricular confeffion ) their worffiip of relicks and images; na^yeVen their tranfubftantiation. But while they acknowledge a foreign power, fuperior to the fo- ^ vereignty of the kingdom, they cannot complain, if the laws of that kingdom will not treat them upon the foot¬ ing of good fubjecls. “ The following are the-laws that have been enacted againft tiie Papifts ; who may be divided into three claffes, perfons profeffing Popery, Popiffi recufants convift, and Popifti priefts. 1. Perfons profeffing the Popiili religion, befides the former penalties for not frequenting their pari fit church, are difabled from taking any lands either by defeent or purchafe, after 18 years of age, until they renounce their errors; they muft at the age of 21 regifter their eftates before acquired, and all future conveyances and wills relating to them; they are incapable of prefenting to any advowfon, or grant¬ ing to any other perfon any avoidance of the iame*; they may not keep or teach any fchool, under pain of perpetual imprifonment; and, if they willingly fay or hear mafs, they forfeit the one 200, the other ico tnerks, and each ftiall fuffer a year’s imprifonment. Thus much for perfons., who, from the misfortune of family prejudices, or otherwifo, have conceived an unhappy at¬ tachment to the Romifli church from their infancy, and publicly profefs its errors. But if any evil induftry is ufed to rivet thefe errors upon them ; if any perfon fends another abroad to be educated in the Popifti re¬ ligion, or to refide in any religious houfe abroad for that purpofe-, or contributes to their maintenance when there ; both the fender, the font, and the contributor, are difabled to fue in law or equity, to be executor or adminiftrator to any perfon, to take any legacy or deed of gift, and to bear any office in the realm ; and fhall forfeit all their goods and chattels, and likewife all their real eftate for life. And where thefe errors are alfo ag¬ gravated by apoftafy or perverfion ; where a perfon is reconciled to the fee of Rome, or procures others to be reconciled, the offence amounts to high treafon, 2. Po¬ pifti recufants, convi&ed in a court of law of not at¬ tending the forvice of the church of England, are fub- jeft to the following difabilities, penalties, and for¬ feitures, over and above thofe before mentioned. They are confidered as perfons excommunicated ; they can hold no office or employment: they muft not keep arms in their houfos, but the fame may be feized by the juf- tices of the peace ; they may not come within 10 miles of London, on pain of look; they can bring no ac¬ tion at law or fuit in equity ; they are not permitted to travel above five miles from home, unlefs by li~ cenfe, upon pain of forfeiting all their goods; ami they may not come to court, under pain of xool. No marriage or burial of fuch recufant, or baptifm of his child, ftiall be had other wife than by the minifters of the church of England, under other fevere penalties. A married woman, when recufant, ftiall forfeit tw7o- thirds of her dower or jointure, may not be executrix or adminiftratrix to her hufband, or have any part of his goods ; and during the coverture may be kept in prifon, unlefs her hufband redeems her, at the rate of jol. a month, or the third part of all his lands. And laftly, as a feme-covert recufant may be imprifoned, fo all others muft, within three months after conviftion, either fubmit and renounce their errors, or, if requi¬ red fo to do by four juftiees, muft abjure and renounce the realm : and if they do not depart, or if they re- F 2 turn Noncofli form i ft s. NON r 44 ] NON Jfoneon- turn without the king’s licence, they fhall be guilty of formii'b. ^ felony? an(l fuffer death as felons, without benefit of Dlackjl. clergy. There is alfo an inferior fpecies of recufancy, Comment, (refilling to make the declaration again!! Popery en¬ joined by ftatute 30 Car. II. ft. 2. when tendered by the proper magiftrate) ; which, if the party refides within ten miles of London, makes him an abfolute recufant convidl ; or, if at a greater diftance, fufpends him from having any feat in parliament, keeping arms in his houfe, or any horfe above the value of 5I. 3. Po- pilh priefts are ftill in a more dangerous condition. By ftatute 11 & 12 W. III. c. 4. Popilh priefts, or bi- Ihops, celebrating mafs or exercifing any part of their fundlions in England, except in the houfes of ambaf- fadors, are liable to perpetual imprifonment. And by the ftatute 27 Eliz. c. 2. any Popilh prieft, born in the dominions of the crown of England, who lhall come over hither from beyond fea (unlefs driven by ftrefs of weather and tarrying only a reafonable time), or lhall be in England three days without conforming and taking the oaths, is guilty of high treafon : and all perfons harbouring him are guilty of felony without the benefit of clergy. “ This is a Ihort fummary of the laws againft the Pa- pifts ) of which the prefident Montefquieu obferves, that they are fo rigorous, though not profeffedly of the fanguinary kind, that they do all the hurt that can poftibly be done in cold blood. But in anfwer to this, it may be obferved (what foreigners who only judge from our ftatute book are not fully apprized of), that thefe laws are feldom exerted to their utmoft ri¬ gour : and indeed, if they were, it would be very dif¬ ficult to excufe them. For they are rather to be ac¬ counted for from their hiftory, and the urgency of the times which produced them, than to be approved (upon a cool review) as a Handing fyftem of law. The reftlefs machinations of the Jefuits during the reign of Elizabeth, the turbulence and uneafinefs of the Pa- pifts under the new religious eftablilhment, and the boldnefs of their hopes and wilhes for the- fucceflion of the queen of Scots, obliged the parliament to coun- teraft fo dangerous a fpirit by laws of a great, and then perhaps neceflary, feverity.. The powden-treafon, in the fucceeding reign, ftruck a panic into James I. which operated in different ways : it occalioned the enabling of new laws againft the Papifts j but deter¬ red him from putting them in execution. The in¬ trigues of Queen Henrietta in the reign of Charles I. the profpedt of a Popilh fucceffor in that of Charles II. the affaffination-plot in the reign of King William, and the avowed claim of a Popifti pretender to the crown in fubfequent reigns, will account for the extenfion of thefe penalties at thofe feveral periods of our hiftory.” But now that all juft fears of a pretender may be faid to have vanilhed, and the power and influence of the * See their p0pe lias become feeble, ridiculous, and defpicable, riot only *n f>rhain, but in almoft every kingdom of throne° 6 Europe : and as in fa£! the Britilh Catholics folemnly May 1. difclaim the dangerous principles afcribed to them * j 1778, as in-the Britilh legiflature, giving way to that liberality of th^Ma^a ^entiment becoming Proteftants, have lately repealed zincs or An-the moft rigorous of the above edifls, viz. The pu- nual Regif- nilhment of Popilh priefts or Jefuits who Ihould be ter for that found to teach or officiate in the fervices of that church j year. which a£ls were felony in foreigners, and high treafon i in the natives of this kingdom —The forfeitures of Noncon- Popilh heirs, who had received their education abroad, and whofe eftates went to the next Proteftant heir :— "v—~ The power given to the fon, or other relation, being a Proteftant, to take poffeffion of the father’s or other relation’s eftate, during the life of the real proprietor : —And the debarring Papifts from the power of ac¬ quiring any legal property by purchafe.—In propo- fing the repeal of thefe penalties, it was obferved, That, belldes that fome of them had now ceafed to be necef- fary, others were at all times a difgrace to humanity. The imprifonment of a Popilh prieft for life, only for officiating in the fervices of his religion, was horrible in its nature : And although the mildnefs of govern¬ ment had hitherto foftened the rigour of the law in the practice, it was to be remembered that the Roman Ca¬ tholic priefts conftantly lay at the mercy of the bafeft and moft abandoned of mankind—of common informers $ for on the evidence of any of thefe wretches, the ma- gifterial and judicial powers were of neceffity bound to enforce all the lhameful penalties of the aft. Others of thefe penalties held out the moft powerful temptations for the commiffion of afts of depravity, at the very thought of which our nature recoils with horror : They feemed calculated to loofen all the bands of fociety ; to diffolve all civil, moral, and religious obligations and duties, to poifon the fources of domeftic felicity, and to annihilate every principle of honour. The encou¬ ragement given to children to lay their hands upon the eftates of their parents, and the reftriftion which de¬ bars any man from the honeft acquilition of property, need only to be mentioned to excite indignation in an enlightened age. In order the better to fecure the Engliffi eftablilhed church againft perils from nonconformifts of all deno¬ minations, Infidels, Turks, Jews, Heretics, Papifts, and Seftaries, there are, however, two bulwarks erefted j called the corporation and tejl a£is: By the former of which, no perfon can be legally elefted to any office relating to the government of any city or corporation, unlefs, within a twelvemonth before, he has received the facrament of the Lord’s fupper according to the rites of the church of England ; and he is alfo en¬ joined to take the oaths of allegiance and fuprtmacy at the fame time that he takes the oath of office : or, in default of either of thefe requifites, fuch eleftion fhall be void. The other, called the teji aSi, direfts all officers civil and military to take the oaths and make the declaration againft tranfubftantiation, in any of the king’s courts at Weftminfler, or at the quarter feffions, within fix calendar months after their admif- fion } and alfo wfithin the fame time to receive the fa¬ crament of the Lord’s fupper, according to the ufage of the church of England, in fome public church im¬ mediately after divine fervice and fermon, and to deli¬ ver into court a certificate thereof figned by the mi- nifter and church warden, and alfo to prove the fame by two credible witneffes 5 upon forfeiture of 500I. and difability to hold the faid office. And of much the fame nature with thefe is the ftatute 7 Jac. I. c. 2. which permits no perfons to be naturalized or reftored in blood, but fuch as undergo a -like teft 5 which teft having been removed in 1753, in favour of the Jews, was the next feffion of parliament reftored again with fome precipitation. Non- NON r 45 ] N O O Non-na- NON-Natura/s, in Medicine, fo called, becaufe by their tin-als abufe they become the caufes of difeafes. Nonius Phyficians have divided the non-naturals into fix ■ claffes, viz. the air, meats and drinks, deep and watch¬ ing, motion and reft, the pafiions of the mind, the re¬ tentions n i...v t been defirous to regard as their exclufive property *, and accordingly a Spaniffi frigate of 26 guns was de-- fpatched from the province of Mexico, for the purpofe of putting an end to this commerce. The Spaniflv- frigate arrived in May 1789, and captured two Eng¬ liffi veffels in the following July, at the fame time tak¬ ing poffeflion' of the little fettlement which had been formed upon the coaft. Such, in ftiort, is the circum¬ ftance which was likely to involve us in an expen- five wrar. Happily, however, for both countries, and1 perhaps for Europe, the matter wras at length, after great altercation, amicably fettled ; and it muft ftill be fo freffi in the memories of our readers, that we truft they will excufe us from enlarging further upon it—the whole article having extended perhaps to more than a fufficient length. NOPAL, Raquette, or Indian Jig; plants fo named by the Indians, on which the cochineal infedl breeds in Mexico. See Cochineal, Dyeing Index. NOPALXOCHQUETZALLI, or Nopalcoch- quetzaeli, the prickly pear of Mexico, which is com¬ mon over all the Weft Indies. See Cactus, Botany Index. NOPH. See Memphis. NORBURY, a town ofStaffordffiire, in England, on the fouth-weft fide of Eccleffiall. Here is a furprifing echo, which, taken 440 yards north-eaft from the ma¬ nor houfe, near a little bank under a wood fide, repeats- in a ftill day 10 or 11 fyllables very diftinftly, or 12 or 13, if fpoke very quick. It is remarked that the banks of the Black Meer, in this pariffi, grow forward every year over the furface of the water at the rate- of three or four yards every feven years. NORDEN, Frederic Lewis, an ingenious travel-- ler and naval-officer in the Daniffi fervice, was born at Gluckftadt in blolftein in the year 1708. He w'as well {killed in mathematics, fliip-building, and efpe- cially in architefture ; and in 1732 obtained a penfion to enable him to travel for the purpofe of ftudying the conftruftion of {hips, particularly the galleys and other rowing veffels ufed in the Mediterranean. He. fpent near three years in Italy j and Chriftian VI. being- defirous of obtaining a circumftantial account of Egypt, Mr Norden while at Florence received an order to ex¬ tend his travels to that country. Flow he acquitted- himfelf in this commiffion, appears from his Travels into Egypt and Nubia, printed at Copenhagen in folio, 1756 5 and which were foon after tranflated into Englifli by Dr Peter Templeman. In the war between Engs,, land and Spain, Mr Norden, then a captain in the Da¬ niffi navy, attended Count Ulric Adolphus, a fea cap^ tain, to England 5 and they went out volunteers under Sir John Norris, and afterwards under Sir Chaloner Ogle. During his ftay in London, Mr Norden was made a fellow of the Royal Society, and gave the public drawings of fome ruins and coluffal ftatues at Thebes in Egypt, with an account of the fame in a letter to the Royal Society, 1741. His health at this time was de¬ clining 5 and taking a tour to France, he died at Paris in 1742. NORDHEIM, a town in Germany, in the Piano, ver r NOR [ 48 ] NOR • Nordheim ver quarter. Of the four larger towns of this princi- Norfoll' Pa%» ^ third in order. It is fituated on the » . ^ J‘" . Iluhme, which runs into the Leine. It contains 500 houfes, and, befides a fecularized Lutheran abbey, has one parifh church, and fome charitable foundations, and alfo enjoys fome manufactures. NORES, Jason de, a fcholar, poet, and philofo- pher, was born at Nicofia in Cyprus. He loft his for¬ tune when the Turks made themfelves mafters of that ifland in 1570. He retired to Padua 5 where he ac¬ quired great reputation by teaching moral philofophy. His character had that call of feverity which is often the confequence of fcholaftic habits. He was one of thofe men who difcufs every thing without being ca¬ pable of feeling any thing. The Pctjlor Fido of Gua- rini made its appearance ; and paftorals became a fa- thionable fpecies of reading throughout all Italy. No- res, who did not relifh works of this kind, attacked the production of Guarini; who entirely confuted him in a little piece printed at Ferrara in 1588. Nores made a reply twro years after 5 and the poet was pre¬ paring an anfwer ftill more fevere than the former, when his antagonift died of grief, occafioned by the banifhment of his only fon for having killed a Vene¬ tian in a duel. He left behind him a great many wmrks, fame in Italian, and others in Latin. The chief of his Italian works, are, 1. The Poetieks, Padua, 1588, qto ; this edition is rare. 2. A Treatife on Republics, 1578, 4to •, which he forms on the model of that of the Venetians, his mafters. 3. A Treatife on the World and its Parts, Venice, 1571, 8vo. 4. Intro¬ duction to three books of Ariftotle’s Rhetoric, Venice, 1S84, 4to, valuable. 5. A Treatife on what Comedy, Tragedy, and Epic Poetry, may receive from Moral Philofophy. His Latin works are, 1. InJUtutio in Philofophiam Ciceronis, Padua, 1576, 8vo. 2. Brevis et diJlinBa fumma preeceptorum de arte difcendi, ex hbris Ciceronis collecia, Venice, 1553, 8vo ; a good v'ork. 3. De ConJHtutione partium humance et civilisphilofophict, 4to. 4. Interpretatio in artem poeticam Horatii, See. In all his works we remark great perfpicuity and ac¬ curacy, profound erudition, happy expreflions, an elevat¬ ed and fometimes forcible ftyle.—His fon Peter Nores, fucceflively fecretary to feveral cardinals, at once a man of letters and a man of bufmefs, left behind him differ¬ ent manuferipts ; among others, the life of Paul IV. in Italian. NORFOLK, a county of England, fo called from its northern fituation in refpeCt of Suffolk, is bounded on the eaft and north by the German ocean 5 on the fouth by Suffolk, from which it is parted by the rivers Waveney and the Leffer Oufe ; and on the weft it is feparated from Cambridgelhire by the Greater Oufe, and from a fmall part of Lincolnlhire by the Wafties. According to Templeman, it extends in length 57 miles, in breadth 35, and 140 in circumfe¬ rence. It contains an area of 1426 fquare miles, one city, 32 market towns, 711 villages, according to the book of rates, though fome make them 1500, and 273,371 inhabitants. It is divided into 31 hundreds, 364 vicarages, and 660 parifties. The air differs in different parts of the county ac¬ cording to the foil, which in fome places is marfliy, efpecially on the fea coaft, and there the air is foggy ^and unwholefome j in others it is clayey and chalky, poor, lean, and fandy, and there the air is good. The county is almoft all champaign, except in fome places, where rife gentle hills. The marlh lands yield rich v pafture for cattle } the clay grounds peafe, rye, and barley 5 and the fandy heaths feed vaft flocks of large ftreep, of which fome villages are faid to keep 4000 or 5000. Thefe heaths abound alfo in rabbits of a filver gray colour. Walftngham is noted for produ¬ cing the beft faffron. Great quantities of mackarel and herring are caught upon the coafts of this county, the former in the fpring, and the latter in September j efpeeially at Yarmouth, where they are cured in a particular manner, and to great perfedtion. Wood and honey are alfo very plentiful in this county ; and on the coafts jet and ambergreafe are fometimes found. The inhabitants are generally ftrong and adtive, fagaci- ous and acute. That they are fo robuft, is the more to be wondered at, becaufe the common people live much on puddings, Norfolk dumplings. They are for the moft part in eafy circumftances, and rvere formerly very quarrelfome and litigious. In confequence of this difpofition, lawyers fwarmed among them to fuch a de¬ gree, that a ftatute was made fo early as the reign of Henry VI. to reftrain their number. The manufadlures of the county, which is exceedingly populous, are chief¬ ly woollen and w or fled fluffs and ftockings, for which they are well fupplied with wool from the vaft flocks of fheep bred in it. It gives title of duke to the elder branch of the family of Howard, lies in the diocefe of Norwich, and fends twelve members to parliament, viz. two knights for the {hire, two citizens for Nor¬ wich, and two burgeffes for each of the boroughs of Lynn Regis, Great Yarmouth, Thetford, and Caftle- rifing. The county is well watered, and fupplied with fifh by the rivers Yare, Thyrn, Waveney, the Greater and Leffer Oufe, and the Bure, befides rivulets. The Bure abounds in excellent perch, and the Yare has a fifli peculiar to it called the ruffe. The latter rifea about the middle of the county 5 and after being joined by the Waveney and Bure, falls into the fea at Yarmouth. At the equinoxes, efpecially the autum¬ nal, the Oufe is fubjeft to great inundations, being forced back by the fea, that enters it with great fury. This county was famous at a very early period for its fiftieries, which were extenfive and valuable, and feem to have been carried on with fpirit. It has alfo been remarkable, for at leaft 400 years paft, for the manu- fafture of fine worfted fluffs. Norfolk, a county of Virginia contiguous to North Carolina. NORFOLK IJlandy a fmall ifland of the South fea, lying in 290 12' 30" fouth latitude, and 1680 16' eaft longi¬ tude. A colony was lately fettled on it ; and the fol¬ lowing account of it is given in Governor Philips's Voyage to Botany Bay, &c. “ Norfolk ifland is about feven leagues in circum¬ ference ; and if not originally formed, like many other fmall iflands, by the eruption of volcanic matter from the bed of the fea, muft doubtlefs have contained a volcano. This conclufion is formed from the vaft quantity of pumice ftone which is fcattered in all parts of it, and mixed with the foil. The crater, or at leaft fome traces of its former exiftence, will probably be found at the fummit of a fmall mountain, which ■ rifes Norfolk, Norfolk Ifland. NOR [ 49 J NOR Norfolk rlfes near the middle of the ifland. To this mountain Wand. t]ie commandant has given the name of Mount Pitt. i{|and is exceedingly well watered. At or near Mount Pitt rifes a flrong and copious dream, which flowing through a very fine valley, divides itfelf into feveral branches, each of which retains fufheient force to be ufed in turning mills j and in various parts of the ifland fprings have been difeovered. “ The climate is pure, falubrious, and delightful ; preferved from oppreflive heats by conllant breezes from the fea, and of fo mild a temperature throughout the winter, that vegetation continues there without interrup¬ tion, one crop fucceeding another. Refrelhing fhowers from time to time maintain perpetual verdure : not in¬ deed of grafs, for none has yet beenfeen upon the ifland j but of the trees, fhrubs, and other vegetables, which in all parts grow abundantly. On the leaves of thefe, and of fome kinds in particular, the flieep, hogs, and goats, not only live, but thrive and fatten very much. To the falubrity of the air every individual in this little colony can bear ample teflimony, from the uninter¬ rupted Hate of good health which has been in general enjoyed. “ When our fettlers landed, there was not a Angle acre clear of wood in the ifland, and the trees were fo bound together by that kind of creeping flirub called fapple jack, interwoven in all directions, as to render it very difficult to penetrate far among them. The commandant, fmall as his numbers rvere at firft, bv indefatigable activity, foon caufed a fpaee to be cleared fufficient for the requilite accommodations, and for the production of efculent vegetables of all kinds in the greateft abundance. When the lafi accounts ar¬ rived, three acres of barley were in a very thriving ftate, and ground was prepared to receive rice and In¬ dian corn. In the wheat there had been a difappoint- ment, the grain that wras fown having been fo much injured by the -weevil as to be unfit for vegetation. But the people were all at that time in commodious houfes ’, and, according to the declarations of Mr King himfelf, in his letters to Governor Philip, there was not a doubt that this colony would be in a fituation to fupport itfelf entirely without afiiffance in lefs than four years*, and with very little'in the intermediate time. Even two years would be more than fufficient for this purpofe, could a proper fupply of black cattle be font. “ Fiffi are caught in great plenty, and in the pro¬ per feafon very fine turtle. The woods are inhabited by innumerable tribes of birds, many of them very gay in plumage. The moft ufeful are pigeons, which are very numerous; and a bird not unlike the Guinea fowl, except in colour (being chiefly white), both of which were at firfl: fo tame as to fuffer themfelves to be taken by hand. Of plants that afford vegetables for the table, the chief are cabbage palm, the wild plantain, the fern tree, a kind of wild fpinage, and a tree which produces a diminutive fruit, bearing fome refemblance to a currant. This, it is hoped, by tranf- planting and care, will be much improved in fize and flavour. “ But the produ&ions which give the greateft im¬ portance to Norfolk Ifland are the pines and the flax plant; the former rifing to a fize and perfe£Hon un¬ known in other places, and promifing the moft valuable Vgl. XV, Part I. fupply of mafts and (pars for our navy in the Eaft In- Norfolk dies ; the latter not lefs eftimable for the purpofes of Iflar|d making failcloth, cordage, and even the finelt manu- jsforia. failures, growing in great plenty, and with fuch luxu- —-y— riance as to attain the height of eight feet. The pines meafure frequently 160, or even 180 feet in height, and are fometimes 9 or 10 feet in diameter at the bottom of the trunk. They rife to about 80 feet without a branch : the -wood is faid to be of the beft quality, al- moft as light as that of the beft Norway mafts; and the turpentine obtained from it is remarkable for purity and whitenefs. The fern tree is found alfo of a great height for its fpecies, meafuring from 70 to 80 feet, and affords excellent food for the ffieep and other fmall cattle. A plant producing pepper, and fuppofed to be the true ori¬ ental pepper, has been difeovered lately in the ifland, growing in great plenty ; and fpecimens have been fent to England in order to afeertain this important point.” NORFOLK Sound, according to the account of Cap¬ tain George Dixon, is fituated in 570 3' north latitude, and 1330 36' weft longitude. It is a very extenfivq place, but how far it ftretches to the northward is not known. There may poffibly be a paffage- through to the Bay of Iflands, but neither is this certain. The ffiore, in common with the reft of the coaft, abounds with pines ; there are alfo great quantities of the witch hazel. There are various kinds of flowering trees and ftirubs, wild goofberries, currants, and rafpberries ; wild parfley is found here in great plenty, and it eats excel¬ lently either as a falad or boiled amongft foup. The faranne, or wild lily root, grows alfo in great plenty and perfection. There are a very few wild geefe or ducks feen here, but they are fhy and difficult of approach. NORHAM, a town in England, in the county of Northumberland, on the river Tweed, near the mouth of the Till, under the caftle, which w-as aneientlv erec¬ ted on a fteep rock moated round, for the better fecuri- ty againft the incurfions of the Scotch mofs troopers. It is of great antiquity ; and its old church has lately re¬ ceived repairs, and been made a decent place of wor- fliip. Antiquities have been difeovered here. The church had the privilege of a fanCluary. The caftle has been frequently honoured with the prefence of fove- reigns, particularly Edward I. here received the oath of treaty from John Baliol of Scotland. It has been a formidable ftructure, a great part of which is in ruins; the lite of which, with its demefnes, confifted of 1030 acres. NORIA, a hydraulic machine much ufed in Spain. It confifts of a vertical wheel of 20 feet diameter, on the circumference of which are fixed a number of little boxes or fquare buckets, for the purpofe of raifing the -water out of the well, communicating with the canal below, and to empty it into a refervoir above, placed by the fide of the wheel. The buckets have a lateral ori¬ fice to receive and to difeharge the water. The axis of this wheel is embraced by four fmall beams, crofting each other at right angles tapering at the extremities, and forming eight little arms. This wheel is near the centre of the horfe w’alk contiguous to the vertical axis, into the top of which the horfe beam is fixed : but near the bottom it is embraced by four little beams, forming eight arms fimilar to thofe above deferibed, on the axis of the waterwheel. As the mule which they ufe goes G round, Noria, Noi'icum NOR [5 round, thefe horizontal arms, fupplying the place of cogs, take hold, each in fucceffion, of thole arms which are fixed on the axis of the water wheel, and keep it in rotation. This machine, than which nothing can be cheaper, throws up a great quantity of water; yet undoubtedly it has two defeats : the firft is, that part of the water runs out of the buckets and falls back into the well after it has been raifed nearly to the level of the refer- voir : the fecond is, that a confiderable proportion of the wrater to be difcharged is raifed higher than the re- fervoir, and falls into it only at the moment when the bucket is at the higheft point of the circle, and ready to defcend. Both thefe defers might be remedied with eafe, by leaving thefe fquare buckets open at one end, making them fwing on a pivot fixed a little above their centre of gravity, and placing the trough of the refervoir in fuch a pofition as to flop their progrefs whilft perpendi¬ cular } make them turn upon their pivot, and fo dif- charge their contents. From the refervoir the water is conveyed by channels to every part of the garden 5 thefe have divifions and fubdivifions or beds, fome large, others very fmall, fepa- rated from each other by little channels, into which a boy with his fhovel or his hoe direfts the water, firft in¬ to the moft diflant trenches, and fucceflively to all the reft, till all the beds and trenches have been either co¬ vered or filled with water. Mr Townfend, from whom we have taken the above account, thinks, that on account of the extreme fimpli- city of this machine, it is an invention of the moll remote antiquity. By means of it the inhabitants every morning draw as much water from the well as will ferve through the day, and in the evening diftribute it to every quarter according to the nature of their crops. The refervoirs into which they raife the water are about 20, 30, or even 40 feet fquare, and three feet high above the furface of the ground, with a flone cope on the wall, declining to the water for the women to wadi and beat their clothes upon. Our limits preclude us from following Mr Townfend farther in the defcription of a particular noria ufed at Barcelona j which he conceives to be the original chain pump, or at leaft its parent. He compares it with fimilar inftruments, and fhows its advantages and difad- vantages. NORICUM (Ptolemy, Tacitus) ; a Roman province, fituated between the Danube on the north, and thus fe- parated from ancient Germany ; the Alpes Noricae on the fouth •, the river iEnus on the weft, which feparates it from Vindelicia 5 and Mons Cetius on the eaft, which divides it from Pannonia. Now containing a great part of Auftria, all Saltzburg, Stiria, and Carinthia. It was anciently a kingdom under its own kings (Caefar, Vel¬ leius, Suetonius). Noricithe people, fubdued by Tibe¬ rius under Augufius, as allies of the Pannonii (Dio, Velleius). Tacitus reckons Noricum among thofe pro¬ vinces which were governed by procurators, officers lent by the emperors to receive and difpofe of the public re¬ venue-according to order. It was divided into two pro¬ vinces, but at what time uncertain j fuppofed as low down as Dioclefian and Conftantine, vix. the Noricum Ripenfe, running along the fouth fide of the Danube j o ] NOR and the Noncum Mediterrancum, extending towards the Noricum Alps. How far each of thefe extended in breadth does II. not appear : all the account we have of the matter be- , ing from Sextus Rufus, and the Notitia Imperii Occiden- talis. Anciently a country famous for its iron and Reel (Horace) 3 as is Stiria at this day, a part of Noricum. A climate cold and more fparingly fruitful (Solinus). N0R1N, a river which rifes in a corner of the Ve¬ netian confines, that runs between the rugged marble hills, and is left entirely to itfelf from its very fource 3 hence a vaft traft of land is overfimved by it, and en¬ cumbered with reeds, willows, and wild alders. A fmall fpace of ground only remains dry between the roots of the hills and the marffi at a place called Prud, and that is all covered with pieces of ancient hewn Rones, fragments of inferiptions, columns, and capitals, and bafs reliefs of the befl age, worn and deformed by time, and the barbarifm of the northern people, who begun on that fide to defiroy Narona. The inhabitants, who go often to cut reeds in the marfli, affert, that the vefliges of that large city may Rill be feen under water. It appears to have been extended over the plain a great way, and un¬ doubtedly it was three miles in length at the foot of the hills. The ancient road is now under water 3 and it is neceffary to afeend a very fteep road, in order to pafs the point of a craggy hill, on which, probably before the Roman times, thofe fortifications were eredted that coR Vetinius fo much labour. NORIS, Henry, cardinal, a great ornament of the order of the monks of St AuguRine, wras defeended from the prefident Jafon, or James de Noris, and was born at Verona 1631. He was carefully educated by his father Alexander Noris, originally of Ireland, and well known by his hiflory of Germany. He difeover- ed from his infancy an excellent underRanding, great vivacity, and a quick apprehenfion. His father inflruc- ted him in the rudiments of grammar, and procured an able profeffor of Verona, called Majfoleim, to be his preceptor. At 15 he wras admitted a penfioner in the Jefuits college at Rimini, where he Rudied philofophy 3 after which he applied himfelf to the writings of the fathers of the church, particularly thofe of St Augu¬ Rine : and taking the habit in the convent of the Au¬ guRine monks of Rimini, he diRinguiffied himfelf among that fraternity in a ffiort time by his erudition : info- much, that as foon as he was out of his noviciate or time of probation, the general of the order fent for him to Rome, in order to give him an opportunity of im¬ proving himfelf in the more folid branches of learning. He did not difappoint his fuperior’s expectations. He gave himfelf up entirely to his Rudy, and fpent whole days, and even nights, in the library of the Angeliques of St Augufline. His conflant courfe was to flick to his books 14 hours a day 3 and this courfe he continued till he became a cardinal. By this means he became qualified to inflruft others 3 and on this errand he was firfl fent to Pezaro, and thence to Peroufa, where he took his degree of doCtor of divinity 3 after which, pro¬ ceeding to Padua, he applied himfelf to finiffi his Hiflo¬ ry of Pelagianifm. He had begun it at Rome at the age of 26 ; and, having completed his defign, the book was printed at Florence, and publilhed in 1673. The great duke of Tufcany invited him the following year to NOR [ - Mens, to tliat city, made him his chaplain, and profeflor of ec- Norkoping. clefiaflical hiftory in the univerfity of Pifa, which his v highnefs liad founded with that view. In his hiftory he fet forth and defended the condem¬ nation pronounced, in the eighth general council, againlt Origen and Mopfuefta, the firit authors of the Pelagian errors : • he alfo added an account of the Schifm of Aquileia, and a Vindication of the Books written by St Auguftine againft the Pelagians and Semi-Pelagians. The work had procured him a great reputation, but met with feveral antagonifts, to whom he publifhed proper anfwers : the difpute grew warm, and was carried be¬ fore the fovereign tribunal of the inquilition. There the hiftory was examined with the utmoft rigour, and the author difmifled without the leaft cenfure. It Avas re¬ printed twice afterwards, and Mr Noris honoured by Pope Clement X. Avith the title of Qualificator of the Holy Office. Mot Avith Handing this, the charge rvas renewed againft the Pelagian Hiftory, and it Avas dila¬ ted afrefti before the inquifition in 1676 ; but it came out again with the fame fuccefs as at firft. Mr Noris Avas noAV fuffered to remain in peace for fixteen years, and taught ecclefiaftical hiftory at Pifa, Avithout any moleftation, till he wras called to Rome bv Innocent XII. Avho made him under-librarian of the Vatican in 1692. This poll was the A\’ay to a cardinal’s hat *, his accufers, therefore, took frefti fire, and publifhed fe¬ veral neAV pieces againft him. Hence the Pope appoint¬ ed fome learned divines, Avho had the character of ha¬ ving taken neither fide, to re-examine Father Noris’s books, and make their report of them. Their teftimo- ny Avas fo advantageous to the author, that his holinefs made him counfellor of the inquifition. Yet neither did this hinder one of his adverfaries, the moft formida¬ ble on account of his erudition, to rife up againft him, and attack him Avarmly, under the afiumed title of a Scrupulous DoElor of the Sorbonne. Noris tried to re¬ move thefe fcruples in a Avork Avhich appeared in 1695, under the title of An Hiftorical Diflertation concerning one of the Trinity that fuffered in the Flelh ; Avherein, having juftified the monks of Scythia, who made ufe of that expreffion, he vindicated himfelf alfo from the im¬ putation of having attainted the Pope’s infallibility, of having abided Vincentius Lirinenfis, and other bifhops of Gaul, as favourers of Semi-Pelagianifm, and of ha¬ ving himfelf gone into the errors of the bilhop of Y pres. His anfvvers to all thefe accufations Avere fo much to the fatisfa&ion of the pope, that at length his holinefs honoured him with the purple in 169 After this, he was in all the congregations, and employed in the moft important affairs; fo that he had little time to fpend in his ftudy, a thing of Avhich he frequently complained to his friends. Upon the death of Cardinal Cafanati, he Avas made chief library keeper of the Vatican in 170O', and two years aftenvards nominated, among others, to reform the kalendar : but he died at Rome in 1704 of a dropfy. He was one of the moft learned men in the laft century j his Avritings abound Avith erudition, and are v'ery elegantly finilhed. He ivas a member of the Aca¬ demy ; Avhence he affirmed the name of Eucrates Ago- rctico. His Avorks arc numerous, and were publifhed at Verona, in 1729 and I73°> *n five volumes folio. NORKOPING, a toAvn of Sweden, in the province of Eaft Gothland, in eaft longitude 150 30', latitude ;i ] NOR 58° 2o'. Its name fignifies “ the northern market,” in Nbrkoping. the SAyedifh language. It ftands on the banks of a Normandy. large river called Mot ala, which coming from the lake Vetter, falls a little lower into a gulf called Brawicken. It is the largeft and moft populous toAvn in Sweden, next to Stockholm, conveniently fituated near the fea on a navigable river, which brings large veffels up to the middle ol the toivn. There are fome handfome ftreets, and the houfes in general are neatly built. Some of the churches are Avorth feeing ; but the greateft curio- fity are the famous copper mines, where there is a A’aft number of people conftantly at Avork. In this article the town carries on a very good trade ; as alfo in feve¬ ral other manufactures, as leather, fteel, and guns, Avhich they make the beft in SAveden. It covers a large fpace of ground, being ten miles in circumference 5 but the houles are fmall and fcattered, and the inhabitants do not exceed io,oco. The river Motala floAvs through the toAvn, forms a feries of cata¬ racts, and is divided into four principal ftreams, Avhich encircle feveral rocky iffands, covered with houfes and manufactories. At the extremity of the town it is na¬ vigable for fmall veffels. Several manufactories are eftablilhed in the toAvn ) 55 fabrics of cloth, which em¬ ploy 1500 men ; 3 fugar-houfes ; 1 of fnuff 5 50 mills for grinding corn, which is exported in large quantities j and a brafs foundery. A falmon fifhery gives employ¬ ment and riches to many of the inhabitants. NORMANDY, a province of France, bounded on the north by the Englilh channel; on the eaft by Picar¬ dy and the Ifle of France; on the fouth by Perche and Maine, and one part of Bretagne ; and on the weft by the ocean. It is about 155 miles in length, 85 in breadth, and 600 in circumference. It is one of the moft fertile, and brings in the largeft revenue of the king¬ dom. It abounds in all things except Avine, but they fupply that defeeft by cyder and perry. There are vaft meadows, fat paftures, and the fea yields plenty of fifh. It contains iron, copper, and a great number of rivers and harbours. It carries on a great trade, is very popu¬ lous, and comprehends a vaft number of toAvns and vil¬ lages. It is divided into the Upper and Loiver j the Upper borders upon Picardy, and the Loiver upon Bre¬ tagne. It contains fe\'en diocefes or bilhoprics, Rouen, Bayeux, Avranches, Evreux, Sees, Lifieux, and Cou- tances, in ivhieh they compute 4189 parilhes, and 80 abbeys. I he inhabitants are ingenious, and capable of underftanding any arts and fciences, but they are chiefly fond of law. The Normans, a people of Denmark and Norway, having entered France under Rollo, Charles the Simple ceded this country to them in 912, Avhich from that time ivas called Normandy, and contains about 8200 fquare miles. Its chief city is Rouen. Rollo Avas the firft duke, and held it as a fief of the croivn of France, and feveral of his fucceffors after him, till Wil¬ liam, the feventh duke, conquered England in 1066 : from ivhicli time it became a province of England, till it ivas loft in the reign of King John, and reunited to the croAvn of France ; but the Englilh ftill keep the illands on the coafts of Normandy. The principal rivers are the Seine, the Eure, the Aure, the Iton, the Dive, the Andelle, the Rille, the Fouque, the Dr6mee, and the Orne : among the fea ports, the principal are thpfe of Dieppe, Havre, Hpnfleur, Cherburg, and Granville. Rouen is the principal city. G 2 ' NORMANS, NOR [5 NORMANS, a fierce •warlike people of Norway, Denmark, and other parts of Scandinavia. They at different times overran and ravaged moft countries in Europe : to the refpeclive hiilories of thofe countries we therefore refer for a fuller account of them, as it is impoffible to enlarge upon particulars in this place with¬ out repeating what has been already faid, or may be faid, in different parts of this work. NORMAN Chambers, a fpecies of writing introduced into England by William I. From fome old manu- feripts the Norman writing appears to have been com- po'ed of letters nearly Lombardic. In regal grants, charters, public inftruments, and law proceedings, this charadler was ufed with very little variation from the reign of the Conqueror to that of Edward III. See Writing. NORRIS, or Noris. See Noris. NORTH, one of the four cardinal points of the world ; being that point of the horizon which is di- reftly oppofite to the fun in meridian. The north •wind is generally accompanied with a confiderable de¬ gree of cold. It fometimes blows with almoft irrefift- ible fury. It is often mentioned by the elaffic authors Under the name of Boreas, which is of Greek original. See Boreas. North Po/e. See Pole. North, Dudley, Lord, the third baron of that ac- complifhed family, was one of the fineft gentlemen in the court of King James ; but in fupporting that cha- rafter, diffipated and gamed away the greateft part of his fortune. In 1645, he appears to have adted with the parliament ; and was nominated by them to be ad- miniftrator of the admiralty, in conjundlion with the great earls of Northumberland, Effex, Warwick, and others. He lived to the age of 85, the latter part of which he palled in retirement j and w'rote a fmall folio of mifcellanies, in profe and verfe, under this title, A Foreft promifeuous of feveral Seafons Produdlions, in four parts, 1659. North, Dudley, Lord, fon of the former, was made knight of the Bath in 1616, at the creation of Charles prince of Wales *, and fat in many parliaments, till ex¬ cluded by the prevailing party in that which condemned the king. From that period Lord North lived privately in the country, and towards the end of his life entertain¬ ed himfelf with books, and, as his numerous iffue requir¬ ed, with economy •, on which he wrote a little tra£I, call¬ ed Obfervations and advices economical, 1 2mo. Flis other works are, Paffages relating to the long parliament; the hiffory of the life of Lord Edward North, the firft baron of the family, addreffed to his eldeft fon 5 and a volume of Effays. NORTH, Francis, Lord Guildford, lord-keeper of the great feal in the reigns of Charles II. and James II. was a third fon of the fecond Dudley lord North, ba¬ ron of Kertling 5 and ftudied at St John’s college in Cambridge, from whence he removed to the Middle Temple. He acquired French, Italian, Spanifh, and Dutch ; and became not only a good lawyer, but wras well verled in hiftory, mathematics, philofophy, and mulic. He was afterwards made the king’s folicitor- general, and was chofen to reprefent the borough of Lynn in parliament. He fucceeded Sir Heneage I inch in the poll: of attorney-general; and Lord Chief-]uf- tice Vaughan, in the place of lord chief-juftice of the 4 ] NOR common pleas. He was afterwards made keeper of North, the great feal; and in 1683 was created a baron by the title of I^ord Guildford. He died at his houfe at Wroxton in 1685. Fie wrote a philofophical effay on mufic ; a paper on the gravitation of fluids, confidered in the bladders of fillies, printed in Lowthorp’s abridge¬ ment of the Philofophical Tranfabtions; and fome other pieces. North, Right Honourable Frcdcrich, earl of Guild¬ ford, Lord North, lord warden and admiral of the Cinque Ports, governor of Dover cattle, lord lieutenant and cuftos rotulorum of Somerfetlhire, chancellor of the univerfity of Oxford, recorder of Glouceffer and Taun¬ ton, an elder brother of the Trinity houfe, prefident of the Foundling hofpital and of the Afylum, a governor of the Turkey Company and of the Charter houfe, K. G. and LL. D. was born April 13. 1732; and married. May 20. 1756, Mifs Ann Speke, an heirefs of the an¬ cient family of Dillington in Somerietlhire, by whom he has left two fons and three daughters : the eldeft fon George Auguftus, born September 11. 1759, and mar¬ ried, September 30. 1785, to Mils Hobart, fucceeds to the earldom and eftates. The late earl fucceeded his fa¬ ther Auguft 4. 1790. His lordlhip fucceeded the cele¬ brated Mr Charles Townfend as manager of the houfe of commons and chancellor of the exchequer ; and in 1770, on the refignation of the duke of Grafton, was made firft lord of the treafury ; in which office he con¬ tinued until the clofe of the American war, or rather until the formation of the Rockingham miniftry, which began the bufinefs of peace with the colonies. He was a man of ftrong mental faculties ; and as an orator, at once commanded attention and enforced conviblion : but taking the helm at a time when the king’s party were unpopular, and when it was fuppofed that the late earl of Bute was the great machine by which the ca¬ binet was moved, fo he continued in that ftate of un¬ popularity until he refigned the feals. During the whole of his premierffiip (and to conduct the helm at that time required uncommonly great abilities) he ftu- dioufly avoided impofing any taxes that fliould mate¬ rially affebt the lower clafs of people. The luxuries, and not the neceffaries, of life were repeated objebts of his budget. As a financier, he flood high, even in the opinion of oppofition ; and they wrere a combi¬ nation of all the great talents in the kingdom : but, fatally wedded to the deftrublive plan of fubduing the republican fpirit of the Americans, his adminiftration will not only Hand marked in the page of hiftory with an immenfe wafte of public treafure, but it will appear befprinkled with the kindred blood of thoufands of Britifli fubjebls. To the very laft moment he fpoke in the fenate, however, he defended that war ; and faid, he w'as then, as he was formerly, prepared to meet the minuteft inveftigation as to his condubt in that bufi¬ nefs ; which nothing but the unforefeen intervention of France could have prevented from being crowned with fuccefs. His lordftiip was one of the firmeft and moft ftrenuous fupporters of the conftitution in church and ftate. He died on the 5th of Auguft 1792. His recolleblion he retained to his laft moments : his fa¬ mily, except Lord North, who came within a few mi¬ nutes afterwards, were affembled round his bed, and he took leave of them individually. Their grief did not fuffer them to leave the room for fome time after the event.; NOR [ Tsorth Faffaee. event *, and Lady Caroline Douglas was at laft forced from it. Even Dr Warren, who niufl be ftrengthened North-weft ag £ar as can operate againft nature to endure fuch feenes, ran from this, convulfed with forrow. If any extent of fympathy can leflen affliction, this family may find fuch relief ; for perhaps no man was ever more generally beloved by all who had accefs to him than the earl of Guildford. We may form an opinion of the eftimation the cele¬ brated univerfity of Oxford entertained of their chan¬ cellor while living, by the very great honour they paid to his remains. About five o’clock in the after¬ noon of the 15th, the great bell at St Mary’s church at Oxford rang out, which was a fignal that the fune¬ ral proceffion had arrived in the environs of that city. The officers of the univerfity, and the whole body of refident Undents, were previoufiy affcmbled in Mag¬ dalen College, in order to pay fome tribute to the memory of their deceaied chancellor. I hey joined the proceffion at Magdalen Bridge, and paraded on foot before the herfe up the high Itreet to Carfax ; from thence down the corn market to St Giles’s church at the town’s end, in a moft folemn manner. Here they halted, and opening to the right and left, the herfe and other carriages palled through, the whole univerfity be¬ ing uncovered. The herfe and attendants then proceeded to Banbury, where his lordlhip’s remains were depofited in the family vault. North Cape, the moft northerly promontory in Eu¬ rope, on the coaft of Norway. E. Long. 2i. 0. N. Lat. 78. o. NORTH Ferry, a fmall village, on the north fide of the frith of Forth, at the Queen’s Ferry paffage. There was here formerly a chapel, ferved by the monks of Dunfermline, and endowed by Robert I. Near it are large whinftone quarries, which partly fupply London with paving ftones, and employ many veflels for the con¬ veyance. “ The granite ( whinftone) (Mr Pennant fays) lies in perpendicular ftrata, and above is a reddifh earth, filled with micaceous friable nodules.” NORTH Foreland, a cape or promontory of Kent, in the ifle of Thanet, four miles call of Margate. Between this and the South Foreland are the Downs, through which all fhips pafs that are bound to or from the weft. E. Long. 1. 2?. N. Lat. 51. 25. NORTH-Wefl Paffage, a paflage to the Pacific ocean through Hudfon’s bay or Davis’s ftraits, and which hath been frequenily attempted without fuccefs *, notwith- ftanding which, many people are ftill of opinion that it is pra£licable. The idea of a paflage to the Eaft Indies by the north pole, or through fome opening near to it, was fuggefted as early as the year 1527. The perfon who had the honour to conceive jdiis idea was Robert Thorne, a mer¬ chant of Briftol, who addrefled two papers on the fub- je - - ^ ' at Mofcow ; from whom, overjoyed at the profpeft of opening a maritime commerce with Europe, he obtain¬ ed privileges for the Englilh merchants, and letters to King Edward VI. who was not, however, alive to re¬ ceive them. In 1585, Mr John Davis in two barks difcovered Cape Defolation, which is fuppofed to be part of Greenland j and two years after advanced as far as Lat. 72°, where he difcovered the flrait which ftill bears his name. To enumerate all the attempts which have been made to difcover a north-eaft paflage, would fwell the article to very little purpofe. The Engliih, Dutch, and Danes, have all attempted it without fuc- cefs. The lait voyage from England for this pur¬ pofe was made in 1676, under the patronage of the duke of York. That unfortunate prince, who wras on all occaflons earnett for the promotion of commerce, and the Lord Berkeley, &c. fitted out a Ihip, com¬ manded by Captain Wood, for an attempt once more to find a north-eaft paflage to India, accompanied with a Ihip of the king’s. They were encouraged to this at¬ tempt, after it had been fo long defpaired of, by feveral new reports and reafonings: fome of which feem not to have been very well grounded—As, “ I. On the coaft of Corea, near Japan, whales had been found with Englifh and Dutch harpoons flick¬ ing in them. This is no infallible proof that fhips could get thither by a north-eaft pafiage, although whales might. “ 2. That, 20 years before, fome Dutchmen had failed within one degree of the north pole, and found it temperate weather there : and that therefore Wil¬ liam Barents, the Dutch navigator who wintered at Nova Zembla in the year 1596, fliould have failed further to the north before turning eaftward ; in which cafe, laid they, he would not have found fo much ob- ftru&ion from the ice. “ 3. That two Dutch Ihips had lately failed 300 leagues to the eaftward of Nova Zembla •, but their Eaft India Company had Hilled that defign, as againft their interell:—and fuch like other airy reports. But this attempt proved very unfortunate. They doubled the North Cape, and came among much ice and drift wood, in 76° of north latitude, fleering to the coaft of Nova Zembla, where the king’s Ihip llruck upon the rocks, and was foon beat to pieces j and Captain Wood returned home with an opinion, “ that fuch a paflage was utterly impracticable, and that Nova Zembla is a part of the continent of Greenland.” Thefe paflages, however, are not yet deemed imprac¬ ticable by all. I he count de Buffon holds it for cer¬ tain, that there is fuch a paflage , and he thinks, that if any farther attempts be made to difcover a paflage to China by the north, it will be neceflary to fleer direCl- ly towards the pole; and to explore the moll open feas, where unqueftionably, fays he, there is little or no ice. 1 his opinion has been revived by the honourable Daines Barrington. See North-POLE. NOR!HALLERTON, a borough town of Eng¬ land, though not incorporated, in the north riding of J orkflure. It fends two members to parliament. The population in 1801 exceeded 2000. In 1138, theNorthallev- Scots arpy under King David was defeated by the t®n» Englilh near this town. It is 34 miles S. from Dur- x °jt0|1am^'' ham, and 223 N. from London. NORTHAMPTON, a town in England, capital of a county of the fame name, fituated in W. Long, o. 55. N. Lat. 52. 15. According to Camden, it was formerly called North-afandon, from its fituation to the north of the river Nen, called anciently Slu- fona, by which and another lefler river it is almofl: enclofed. Dr Gibfon fays, that the ancient Saxon annals called both it and Southampton limply Hamp¬ ton ; and afterwards, to diltinguilh them, called the one, from its fituation, Southampton, and the other Northampton; but never North-afandon. Though it does not appear to be a place of very great antiquity, nor to have emerged* from obfcurity till after the Con- queft, it has fent members to parliament lince the reign of Edward 1. and being in the heart of the kingdom, feveral parliaments have been held at it. There was alfo a caftle, and a church dedicated to St Andrew, built by Simon de Sandto Licio, commonly called Sen/e%, the firft earl of Northampton of that name. It is faid to have been burnt down during the Danilh depredations ; but in the reign of St Edward it appears to have been a confiderable place. It was be- fieged by the barons in their war with King John 5 at which time that military wmrk called Hunjkill, is fup¬ pofed to have been raifed. In the time of Henry III. it fided with the barons, when it was befieged and taken by the king. Here the bloody battle was fought in which Henry VI. was taken prifoner. It was en¬ tirely confumed by a moft dreadful fire in 1675 •, yet, by the help of liberal contributions from all parts of the country, it hath fo recovered itfelf, that it is now one of the neateft and beft built towns of the kingdom. Among the public buildings, which are all lofty, the moft remarkable are the church called All-hallows (which Hands at the meeting of four fpacious ftreets), the feffions and aflize houfe, and the George inn, which belongs to the poor of the town. A county hofpital or infirmary has been lately built here, after the manner of thofe of Bath, London, Briftol, &c. It has a con¬ fiderable manufacture of flhoes and ftockings 5 and its fairs are noted for horfes both for draught and faddle ; befides, it is a great thoroughfare for the north and weft roads. It was formerly walled, and had feven churches within and two without. The horfe market is reckoned to exceed all others in the kingdom, it be¬ ing* deemed the centre of all its horfe markets and horfe fairs, both for faddle and harnefs, and the chief rendezvous of the jockies both from York and London. Its principal manufacture is fhoes, of which great num¬ bers are fent beyond fea \ and the next to that, ftock¬ ings and lace, as we have hinted at above. It is the richer and more populous, by being a thoroughfare both in the north and weft roads ; but, being 80 miles from the fea, it can have no commerce by navigation. The walls of this town were above two miles in com- pafs. The number of inhabitants in 1801 exceeded 7000. It had formerly a nunnery in the neighbouring meadows, with feveral other monafteries; and of its very old caftle on the weft fide of the town, a fmall part of the ruins is ftill to be feen. Some difcontented fcholars NOR North Kock.s. Northamp- Scholars came hither from Oxford and Cambridge, about ton the end of the reign of Henry III. and, with the king s leave, profecuted their ftudies here academically tor three years ; during which there was the face of an ' univerfity, till it was put a flop to by exprefs. prohibi¬ tion, becaufe it was a damage to both univerfities. The public horfe races are on a neighbouring down, called Pey-Leys. In and about the town are abundance of cherry gardens. W ithin half a mile of the towrn is one of the croffes ere&ed by King Edward I. in memory of his queen Eleanor, whofe corpfe was relied there m its way to Weftminfter. On the north fide of the river, near that crofs, many Roman coins have been ploughed up. At Guilelborough, north-weft of Northampton, are to be feen the veftiges of a Roman camp, the fitua- tion of which is the more remarkable, as lying between the Nen and the Avon, the only pafs from the north to the fouth parts of England not intercepted by any river. This camp was fecured only by a Angle intrenchment, which was, however, very broad and deep. Northampton, a county of North America, in Virginia, forming the fouth part of the peninfula on the ealtern coaft of Virginia. NORTHAMPTONSHIRE, a county of England, is fituated in the very heart of the kingdom : bounded on the eail by the counties of Bedford and Huntingdon ; on the fouth by thofe of Buckingham and Oxford ; on the the weft by Warwicklhire 5 and on the north by the counties of Leicefter, Rutland, and Lincoln, which are feparated from it by the Leffer Avon, and the Welland. Its greateft length is about 50 miles, its greateft breadth about 20, and its circumference about 130. It con¬ tains 336 parilhes, one city, eleven market towns, 23,000 houfes, and in 1801 the inhabitants amounted to I3i,737. Nine members are returned to parliament for this county, viz. two knights for the Ihire, two for the city of Peterborough, twTo for each of the towns of Northampton and Brockly, and one for Higham Fer¬ rers. It lies in the midland circuit, and in the diocefe of Peterborough. As this county is dry, well culti¬ vated, free from marlhes, except the fens about Peter¬ borough, in the centre of the kingdom, and of courfe at a diftance from the fea, it enjoys a very pure and whole- fome air. In confequence of this, it is very populous, and fo full of towns and churches, that 3o fpires or fteeples may be feen in many places at one view j and even in the fens the inhabitants feem to enjoy a good ftate of health, and to be little affefted by the water which frequently overflows their grounds, efpecially in winter, but is never fuffered to remain long upon it. Its foil is exceeding fertile both in corn and pafturage •, but it labours under a fcarcity of fuel, as it doth not pro¬ duce much wood, and by lying at a diftance from the fea, cannot be eaflly fupplied with coal. Its commodi¬ ties, befides, corn, are (beep, wool, black cattle, and falt- petre •, and its manufactures are ferges, tammies, {bal¬ loons, boots, and (hoes. Befides many leffer brooks and ftreams, it is well watered by the rivers Nen, Welland, Oufe, and Lerm ; the three firft of which are large, and for the mod part navigable. NORTH rocks, (otherwife called St Patrick's rocks, from a feat of ftone amongft them called St Patrick's chair, whence the rocks have taken this fecond name); fituated in the harbour of Donaghadee, in the county of Down, and province of Ulfter, in Ireland. From [ 56 ] NOR north to fouth they are about two-thirds of a league, betw'een which is clean good ground. But care muft be taken of the fouth rock, on which many {hips have perifhed: for it is overflowed by every tide, and no crew can fave their lives if the wind blows high. This rock Hands a full mile from the fhore. NORTH sea. See North Sea. NORTHERN lights, the fame with Aurora borealis, under which article we have given a co¬ pious account of this phenomenon, and of the fup- pofed caufes of it. Natural fcience, however, does not arrive at perfection at once, and it is well if it does fo after trials repeated for years wdth care and accuracy. How far the caufes that have been afligned for this appearance will account for it, or whether they wrill be able to remove all difficulties, it is not for us to de¬ termine ; but it is the part of philofophers to hear all {ides, and to attend wTith patient afliduity to every hy- pothefis, rejecting or receiving, as reafon, after the ftriCteft invelligation, {hall feem to favour the one fide or the other. We fliall here notice a hypothefts which DoClor Stearns, an American, formed, about the year 1788, to account for the appearances called aurora bo¬ realis, anu aurora aujlrahs. DoClor Stearns fuppofes that thefe phenomena ori¬ ginate from aqueous, nitrous, fulphureous, bituminous, and other exhalations, from the fumes of various kinds of earths or other minerals, vegetables, ■animals, fires, volcanoes, &c. Thefe, he thinks, become rarefied, and being charged with electrical fluid, become fpeci- fically lighter than the circumambient air •, hence, of courfe, they afcend ; and being elevated to the upper regions of the air, and driven by the winds irom warmer to colder climates, the cold makes them combine and ‘ ftiffen. When they are afterwards agitated by dif¬ ferent currents of air, they fparkle and crackle like the hairs of cats and other animals when lliffened with cold. This corufcation in quite cold atmofpheres, and in thofe which are more temperate, appears in different politions in the horizon, zenith, or otherwife, according to the fituation of the fpeClator, and the pofition of the elevated exhalations. The difference of colours the doCtor fup¬ pofes to arife from the different qualities of the articles combined, thofe of the moil inflammable nature thining with the greateft luitre. The dodlor likewife tries to account for thefe lights not appearing, or but feldom appearing, in ancient times. The atmofphere, he thinks, was not impreg¬ nated with materials proper to produce them. He ima¬ gines that the increafed confumption of fuel, in A- merica in particular, the burning of volcanoes, and the approach of blazing ftars, whofe atmofpheres have been fo expanded by the fun’s heat that part of them have fallen into the earth’s atmofphere, and communicated to it new matter, have fo changed and prepared our air, that whenever its confiftence is proper, then, if the light of the fun and moon is not too powerful, the aurora borealis will appear. NORTHUMBERLAND, the mod northerly coun¬ ty of England, and formerly a dirtincl kingdom, is bounded on the north and weft by the river Tweed, which divides it from Scotland, the Cheviot hills, and part of Cumberland ■, w^aftied on the eaft by the Ger¬ man ocean •, and feparated from Durham on the fouth by the rivers Tyne and Derwent. This county, which North Rocks It Northum. berland, #•7 ortlium f berlaiid. NOR [ 57 gives the title of duke to a nobleman, who married the daughter of Algernon duke of Somerfet, whbfe J motlier was heirefs of the Percy family, extends about 66 miles in length from north to fouth, and about 47 in breadth from eaft to well. It is remarkably popu¬ lous, containing 12 market towns, 280 villages, and 460 parilhes. The face of the country, efpecially to¬ wards the weft, is roughened with huge mountains, the moft remarkable of which are the Cheviot hills, and the high ridge called Redefdale ; but the lands are level towards the fea fide and the borders of Durham. The climate, like that of every other mountainous country in the neighbourhood of the fea, is moift and dilagree- able : the air, however, is pure and healthy, as being well ventilated by breezes and ftrong gales of wind j and in winter mitigated by the warm vapours from the two Teas, the Irilh and the German ocean, between which it is fituated. The foil varies in different parts of the county. Among the hills it is barren ; though it affords good pafture for (beep, which cover thofe moun¬ tains. The low country, when properly cultivated, produces plenty of wheat, and all forts of grain ; and great part of it is laid out in meadow lands and rich en- clofures. Northumberland is well watered with many rivers, rivulets, and fountains : its greateft rivers are the Tweed and the Tyne. The Tyne is compofed of two ftreams called South and North Tyne: the firft rifes on the verge of Cumberland, near Alfton moor •, enters Northumberland, running north to Haltwhiftle; then bends eafterly, and receiving the two fmall rivers Eaft and Weft Alon, unites above Hexham with the other branch, taking its rife at a mountain called Fane-head in the weftern part of the county, thence called Tyne- dale ; is fwelled in its courfe by the little river Shele ; joins the Read near Billingham 5 and running in a direct line to the fouth-eaft, is united with the fouthern Tyne, forming a large river that wafhes Newcaftle, and falls into the German ocean near Tynemouth. In all probability the mountains of Northumberland contain lead ore and other mineralized metals in their bowels, as they in all refpefts referable thofe parts of Wales and Scotland where lead mines have been found and prdfecuted. Perhaps the inhabitants are diverted from inquiries of this nature, by the certain profits and conftant employment they enjoy in working the coal pits, with which this county abounds. The city of London, and the greateft part of England, are fup- plied with fuel from thefe ftores of Northumberland, which are inexhauftible, enrich the proprietors, and employ an incredible number of hands and Hupping. About 658,858 chaldrons are annually (hipped for London. There are no natural woods of any confequence in this county, but many plantations belonging to the feats of noblemen and gentlemen, of which here is a great number. As for pot herbs, roots, falading, and every article of the kitchen garden and orchard, they are here raiftd in great plenty by the ufual means of cultivation j as are alfo the fruits of more delicate flavour, fuch as the apricot, peach, and ne&arine. The fpontaneous fruits it produces in common with other parts of Great Britain, are the crab-apple, the floe or bullace, the hazel nut, the acorn, hips, and haws, with the berries of the bramble, the juniper, wood ftraw- berries, cranberries, and bilberries. Vox.. XV. Part I. berland. ] NOR Northumberland raifes a good number of excellent Northum- horfes and black cattle, and affords palture for numer¬ ous flocks of fheep 5 both the cattle and fheep are of a large breed, but the wool is coarfer than that which the more fouthern counties produce. The hills and mountains abound with a variety of game, fuch as red deer, foxes, hares, rabbits, heathcock, groufe, partridge, quail, plover, teal, and woodcock: indeed, this is counted one of the beft {’porting counties in Great Bri¬ tain. The fea and rivers are well flocked with fiih ; efpecially the Tweed, in which a vaft number of fal- mon is caught and carried to Tynemouth, where being pickled, they are conveyed by lea to London, and fold under the name of Newcajlle falmon. The Northumbrians were anciently ftigmatized as a favage, barbarous people, addicled to cruelty, and in¬ ured to rapine. The truth is, before the union of the two crowns of England and Scotland, the borderers on each fide were extremely licentious and ungovernable, trained up to war from their infancy, and habituated to plunder by the mutual incurfions made into each kingdom ; incurfions which neither truce nor treaty could totally prevent. People of a pacific difpofition, w'ho propofed to earn their livelihood by agriculture, would not on any terms remain in a country expofed to the firft violence of a bold and defperate enemy j therefore the lands lay uncultivated, and in a great meafure deferted by every body but lawlefs adventur¬ ers, who fubfifted by theft and rapine. There was a tradt 50 miles in length and fix in breadth, between Berwick and Carlifle, known by the name of the de- bateable land, to which both nations laid claim, though it belonged to neither *, and this was occupied by a fet of banditti who plundered on each fide, and what they Hole in one kingdom, they fold openly in the other : nay, they were fo dexterous in their occupation, that by means of hot bread applied to the horns of the cattle which they Hole, they twifted them in fuch a manner, that, when the right owners faw them in the market, they did not know their own property. War¬ dens were appointed to guard the marches or borders in each kingdom 5 and thefe offices were always con¬ ferred on noblemen of the firft character for influence, valour, and integrity. The Englifli border was divided into three marches, called the eajl, vuejl, and middle marches ; the gentlemen of the county were conftituted deputy wardens, w7bo held march courts, regulated the watches, difeiplined the militia, and took meafures for aflembling them in arms at the firft alarm : but in the time of peace between the two nations, they were chiefly employed in fuppreffing the infolence and rapine of the borderers. Since the union of the crowns, how¬ ever, Northumberland is totally changed, both with refpefft to the improvement of the lands, and the refor¬ mation of the inhabitants. The grounds, being now fecure from incurfion and infult, are fettled by creditable farmers, and cultivated like other parts of the kingdom. As hoftilities have long ceafed, the people have forgotten the ufe of arms j and exercife themfelves in the more eligible avocations of peace, in breeding fheep and cat¬ tle, manuring the grounds, working at the coal pits, and in different branches of commerce and manufacture. In their perfons they are generally tall, ftrong, bold, hardy, and frefh coloured ; and though lefs unpolifhed than their anceftors, not quite fo civilized as their H fouthern ' NOR [5 Northum- fouthern neighbours. The commonalty are well fed, berland i0(iged? ancJ clothed j and all of them remarkably dif- Norton’* by a kind of Jhibboleth or whurle, being a Sound, particular way of pronouncing the letter R as if they -V-"—' hawked it up from the windpipe, like the cawing of rooks. In other refpefts, the language they fpeak is an uncouth mixture of* the Englhh and ScottHh dialefts. There is no material diftindion between the fafhionable people of Northumberland and thofe of the fame rank in other parts of the kingdom ; the fame form of edu¬ cation will produce the fame effedts in all countries. The gentlemen of Northumberland, however, are dif- tinguiihed for their induftry, knowledge of rural affairs, and hofpitality. The number of inhabitants in 1801 was reckoned at 157,101 ; of houfes 22,740, A great number of Roman monuments have been found in this county, but the moil remarkable curio- fity of that kind confiils in the remains of Hadrian’s vallum and the wall of Severus. See ADRIAN, note (a), and Severus's Wall. The moft noted towns in Northumberland, are New- caftle, Morpeth, Alnwick, Berwick, Hexham, and North Shields. It fends two members to parliament. NORTHWICK, a fmall town of Cheihire, long celebrated for its rock fait and brine pits. The itra- tum of fait lies about 40 yards deep ; and fome of the pits are hollowed into the form of a temple. The de- fcent is through a dome, the roof fupported by rows of pillars about two yards thick, and feveral in height j and when illuminated with a fufficient number of candles, they make a moft magnificent appearance. Above the fait is a bed of whitifh clay, (Argilla ccerula-cmerea), ufed in making the Liverpool earthen rvare •, and in the fame place is alfo dug a good deal of the gypfum, or plafter ftone. The fodil fait is generally yellow, and lemipellucid, fometimes debafed with a dull greenilh earth 5 and is often found, but in fmall quantities, quite clear and colourlefs. The town is fituated near the river Dane, and is tolerably handfome : it has a market on Fridays. It is 20 miles north-eaft of Chefter, and 173 north-weft of London. W. Long. 2. 36. N. Lat. 53- l6- NORTON, in Cheftiire, a good modern alms-houfe, founded by P—y Brooke, Efq. on the fite of a priory of canons regular of St Auguftine, founded by William, fon of Nigellus, A. D. 1135, who did not live to com¬ plete his defign •, for Euftace de Burgaville granted to Hugh de Catherine pafture for 100 fheep, in cafe he finilhed the church in all refpefts conformable to the in¬ tent of the founders. It was granted afterwards to R. Brooke, Efq. NORTON’S SOUND, was difcovered in Captain Cook’s laft voyage, and was fo named in honour of Sir Fletcher Norton (Lord Grantley), a near relation of Mr afterwards Dr King. It extends as far as N. Lat. 64° 55'. There is no good ftation for (hips, nor even a tolerable harbour in all the found. Mr King, on his landing here, difcerned many fpaeious valleys, with rivers flowing through them, well wooded, and bounded with hills of a moderate height. One of the rivers to¬ wards the north-weft feemed to be confiderable •, and he was inclined to fuppofe, from its direftion, that it dif- charged itfelf into the fea from the head of the bay. Some of his people, penetrating beyond this into the country, found the' trees to be of a larger fize the 3 8 ] NOR further they proceeded. E. Long. loy. ij. N. Lat. Norton’*. 6 ^ 01 ‘ Sound, NORWAY, a country of Europe (for the map fee . Denmark), lying between the 57th and 72d degrees of north latitude, and between the 5th and 31ft de¬ grees of longitude eaft from London ; extending in length about 1000 miles, in a diredt line from Lindef- naes, in the diocefe of Chriftianfand, to the North Cape, at the extremity of Finmark. Its breadth, from the frontiers of Sweden weftward to Cape Statt, may amount, to about 300 miles j but from thence the coun¬ try becomes gradually narrower towards the north. On the fouth it is bounded by the Schagen rock, or Categate, the entrance into the Baltic; on the eaft it is divided from Sweden by a long ridge of high moun¬ tains ; and on the weft and north it is wafhed by the northern ocean. In the fouthern part of Norway, the country is craggy, abrupt, and mountainous, diverfi- fied fometimes with fertile and even delightful foots. In thefe refpedls it refembles Switzerland : the pro- fpedts and the meteorological phenomena feem to be very fimilar. The range of the thermometer is of great extent; in the fummer having rifen to 88°, and in the winter fallen to —40° : in general it is between 8o° and —22°. Refpedling the population of Norway it is difficult to attain to certainty. An author of fome note (Coxe) feems to think it amounts to 750,000 ; but .he appears to have over-rated it confiderably. The Norwegian peafants are free, well clothed, well lodged, fpirited, aftive, frank, open, and undaunted. They are faid to have a very confiderable refemblance to the peafants of Switzerland. The foil is too thin for the plough : corn is therefore obtained from the neighbouring ftates and the chief employment of the peafants of Norway is grazing. The following extradl from Mr Coxe, being a defeription of the feene near Chriftiana, is not befide our purpofe, and may not per¬ haps be difagreeable to our readers. “ As we approached Chriftiana, the country VizsCoxe'sTra- more wild and billy, but ftill very fertile and agree- able •, and about two miles from the town we came to the top of a mountain, and burft upon as fine a view as ever I beheld. From the point on which we flood in raptures, the grounds laid out in rich enclofures, gradually Hoped to the fea *, below us appeared Chrif¬ tiana, fituated at the extremity of an extenfive and fertile valley, forming a femicircular bend along the ffiore of a moft beautiful bay, which, being enclofed by hills, uplands, and forefts, had the appearance of a large lake. Behind, before, and around, the inland mountains of Norway rofe on mountains covered with dark forefts of pines and fir, the inexhauftible riches of the north. The moft diftant fummits -were caped with eternal fnow. From the glow of the atmofphere, the warmth of the weather, the variety of the produc¬ tions, and the mild beauties of the adjacent feenery, I could fcarcely believe that I was nearly in the 60th de¬ gree of northern latitude.” The coaft of Norway, extending above 300 leagues, is ftudded with a multitude of fmall iflands, affording habitation to fiftiermen and pilots, and pafture to a few cattle. They form an infinite number of narrow channels, and a natural barrier of rocks, which ren¬ ders Norway inacceffible to the naval power of its ene- mies.. N O ft * [ 59 1 NOR Norway, mies. Attempts of this kind are the more dangerous, as the fnore is generally bold, deep, and impending ; fo that clofe to the rocks the depth of the fea amounts to 100, 200, or 300 fathoms. The perils of the north fea are moreover increafed by hidden ftorms, funk rocks, violent currents, and dreadful whirlpools. T he moft remarkable vortex on this coaft is called Mojltoe- Jirom, from the fmall illand Molkoe, belonging to the diltrift of Lofoden in the province of Nordland. In time of flood, the ftream runs up between Lofoden and Moikoe with the moft boifterous rapidity; but in its ebb to the fea, it roars like a thoufand cataradls, fo as to be heard at the diftance of many leagues. The furface exhibits different vortices ; and if in one of thefe any (hip or veffel is abforbed, it is whirled down to the bottom, and daftied in pieces againft the rocks. Thefe violent whirlpools continue without intervals, except for a quarter of an hour, at high and low Ava- ter, in calm weather ; for the boiling gradually returns as the flood or ebb advances. When its fury is height¬ ened by a ftorm, no veffel ought to venture within a league of it. Whales have been frequently abforbed within the vortex, and howded and bellowed hideoufly in their fruitlefs endeavours to difengage themfelves. A bear, in attempting to fwim from Lofoden to Mof- koe, was once hurried into this whirlpool, from whence he ftruggled in vain for deliverance, roaring fo loud as to be heard on fliore ; but notivithftanding all his efforts, he was borne down and deftroyed. Large trees being abforbed by the current are fucked down, and rife again all fhattered into fplinters. There are three vortices of the fame kind near the iflands of Ferroe. Norway is divided into the four governments of Ag- gerhus, Bergen, Drontheim, and Wardhus, befldes that of Bahus, which is now fubjeft to Sweden. The pro¬ vince of Aggerhus comprehends the fouth-eaft part of Nonvay, extending in length about 300 miles. Its chief towns are Chriftiana, the fee of a Sifliop, fuffragan to the metropolitan fee of Drontheim, where the fovereign court of juftice is held, in prefence of the viceroy and the governor of the province ; Aggerhus, about 15 miles to the fouth-weft of Chriftiana ; Frederickfhall or Fre- derickftadt, in the fiege of which Charles XII. of Sive- den loft his life 5 Saltzberg, Tonfberg, Alleen, Ham- mar, and Hollen. The government of Bergen lies in the moft fouther- iy and rvefterly part of Norway, including the city of the fame name, which is an epifeopal fee, and a place of confiderable trade 5 and Staffhanger, fituated in the bay of Buckenfior, about 80 miles to the fouth- Avard of Bergen. The third province, called Dron¬ theim or Trontheim, extends about 500 miles along the coaft ; and is but thinly peopled. The chief town, Drontheim, feated on a little gulf at the mouth of the river Nider, is the only metropolitan fee in Nonvay 5 and carries on a confiderable trade in mails, deals, tar, copper, and iron. Leetftrand, Stronden, Scoerdale, Opdal, Romfdael, and Solendael, are like wife places of fome traffic. The northern divifion of Drontheim, call¬ ed fub-government of Sa/ten, comprehends the toAvns Melanger and Scheen. The province of Wardhus, ex¬ tending to the North Cape, and including the iflands, is divided into tAvo parts ; namely, Finmark and Nor- AA'egian Lapland. The chief toAvn, which is very in- confiderabF, ftands upon an ifland called Ward, from Avhence the place and the government derive their name. Norway. The province of Bahus, though now yielded to the Swedes, is reckoned part of Norway, being a narrovv tradl of land, about 90 miles in length, lying on the coaft of the Categate. The great chain of Non\ray mountains, running from north to louth, called indifferently Rudfield, Sudefe/d, Skarsfeld, and Score berg, is knoivn in different parts by other appellations ] fuch as Dofrefe/d, Lamsfeld, Sag- nifield, Filefeld, Halnefeld, Hardangerfield, Joklefeld, Byglejield, Hick/efeld, and Hangfe/d. The height and breadth of this extenfive chain likeAvife vary in different parts. To pafs the mountain Hardanger, a man muft travel about 70 F.nglifti miles, whereas Filefield may be about 50 over. This laft rifes about tivo miles and a half in perpendicular height 5 but Dofrefield is counted the higheft mountain of Norway, if not of Europe. The river Drivane Avinds along the fide of it in a ler- pentine courfe, fo as to be met nine times by thofe ivho travel the Avinter road to the other fide of the chain. The bridges are throwm over roaring cataradls, and but indifferently faftened to the fteep rocks on either fide j fo that the whole exhibits a very dreadful appearance, fufficient to deter the traveller from hazarding fuch a dangerous paflage 5 for ivhich reafon, people generally choofe the road over Filefield, Avhich is much more te¬ dious. This, hoAvever, is the poft road ufed by the king’s carriages. The Avay is diftinguiffied by polls fixed at the diftance of 200 paces from each other, that, in fnoivy or dark Aveather, the traveller may not be be- wildered. For the convenience of refting and refrefn- ing, there are two mountain ftoves or houfes maintain¬ ed on Filefield, as Avell as upon other mountains, at the expence of the public, and furniftied Avith fire, light, and kitchen utenfils. Nothing can be more difmal and dreary than thofe mountains covered i\'ith eternal fnow, where neither houfe, tree, nor living creature is to be feen, but here and there a folitary rein deer, and per¬ chance a few Avandering Laplanders. In travelling from SAVeden to Nordenfields, there is only one Avay of avoiding this chain of mountains j and that is, where it is interrupted by a long deep A^alley, extending from Romfdale to Guldbrandfdale. In the year 1612, a body of 1000 Scots, commanded by Sin¬ clair, and font over as auxiliaries to the SAVedes, were put to the fword in this defile, by the peafants of Guld- brand, Avho never give quarter. Befides this chain, there is a great number of de¬ tached mountains over all the country, that form Aral- leys and ridges, inhabited by the peafants. Some of thefe are of incredible height, and others exhibit very remarkable appearances. In failing up Joering Creek on the left hand, the fight is aftonilhed Avith a group of mountains, refembling the profpect of a city, Avith old Gothic toAvers and edifices. In the parifti of Oerikong is the high mountain Skopfhorn, the top of which repre- fents the figure of a fortification, with regular Avails and baftions. In the diftridl of Hilgeland appears a very high range of mountains, Avith feven pinnacles or crefts, knoivn by the appellation of the Seven Sifters, difeern- ible a great way off at fea. To the foutliAvard of this range, though in the fame diftrift, rifes the famous mountain Torghatten, fo called becaufe the fummit re- fembles a man’s head with a hat on, under which ap¬ pears a Angle eye, formed by an aperture through the H a mountain} N O 11 [ 60 ] NOR Norway, mountain, 150 ells high, and 3000 ells in length. 1 he v~—' fun may be feen through this furprifmg cavity, which is paflable by the loot of travellers. On the top oi the mountain we find a refervoir of water, as large as a mo¬ derate fiih pond : in the lower part is a cavern, through which a line 400 fathoms in length, being let down, did not reach the bottom. At Herroe in Sundmoer is another cavern called Doljleen, fuppofed to reach under the fea to Scotland j which, however, is no more than an idle tradition. In the year 1750, tw-o clergymen entered this fubterranean cavity, and proceeded a con- fidenable wav, until they heard the fea dafliing over their heads: the paffage is as wide and high as an ordi¬ nary church, the Tides perpendicular, and the roof vault¬ ed. They defeended one flight of natural Hairs •, but arriving at another, they were afraid to penetrate far¬ ther : they had gone fb far, however, that two candles were confiimed in their progrefs and return. A cavern of a very curious nature, ferving as a conduit to a dream of water, penetrates through the Tides oi the mountain Limur. In the diftrift of Rake, in the neighbourhood of Frtderiekdiall, are three cavities in a rock j one of which is fo deep, that a fmall itone dropped down does not reach the bottom in lefs than two minutes \ and then the found it produces is pleafant and melodious, not unlike the found of a bell. The vaft mountains and rugged rocks that deform the face of this country are productive of numberlefs incon¬ veniences. They admit of little arable ground : they render the country in feme parts impaffable, and every¬ where difficult to-travellers : they afford {belter to wild beads, which come from their lurking holes, and make terrible havock among the flocks of cattle: they expofe the fheep and goats, as well as the peafants, to daily ac¬ cidents of falling over precipices: they occafion fudden torrents, and falls of fnow, which defeend with incre¬ dible impetuofity, and often fweep away the labours of the huflxmdman •, and they are fubjeft to dread&l dif- ruptions, by which huge rocks are rent from their Tides, and, hurling down, overwhelm the plains below with inevitable ruin. The peafants frequently build their houfes on the edge of a fteep precipice, to which they muff climb by ladders, at the hazard of their lives; and when a perfon dies, the corpfe muff be let down with ropes, before it can be laid in the coffin. In winter the mail is often drawn up the Tides of fteep mountains. Even in the king’s road, travellers are expofed to the frequent rilks of falling over tbofe dreadful rocks ; for they are obliged to pafis over narrow pathways, without rails or riling on the fides, either {bored up with rotten ports, or fufpended by iron bolts faftened in the moun¬ tains. In the narrow pafs of Naeroe is a remarkable way of this kind, which, above 600 years ago, the fa¬ mous King Surre caufed to be made for the paffage of Lis cavalry ; and even this would have been found im¬ paffable by any other horfes than thofe of Norway, which are ufed to climb the rocks like goats. Another very difficult and dangerous road is that between Shog- fladt and Vang-in-Voider*, along the fide of a fteep mountain, in fome places fo narrow, that if two travel¬ lers on horfeback fliould meet in the night, they would find it impracticable either to pafs each other, or turn back. In fuch a cafe their lives could not be faved, unlefs one of them fhould alight, and throw his horfe headlong into the lake below, and then cling to the rock, until the other could pafs. When a {beep or goat Norway, makes a falfe ftep to the projection of a rock, from l"n v—“ whence it can neither afeend nor defeend, the owner hazards his own life to preferve that of the animal. He direCts himfelf to be lowered down from the top of the mountain, fitting on a crofs flick, tied to the end of a long rope ; and when he arrives at the place where the creature {lands, he fallens it to the fame cord, and it is drawn up with himfelf. Perhaps the other end of the rope is held by one perfon only ; and‘there are fome in* fiances in which the afliliant has been dragged down by the weight of his friend, fo that both have periihed. When either man or beaft has had the misfortune to fall over very high precipices, they have not only been fuf- focated by the repercuflion of the air, but their bodies have been always burft before they reached the ground. Sometimes entire crefts of rocks, many fathoms in length and breadth, have fallen down at once, creating fuch a violent agitation of the air, as feemed a prelude to the world’s diffolution. At Steenbroe in Laerdale, a flu- pendous rnafs, larger than any caftle in theuniverfe, ap¬ pears to have been fevered and tumbled from the moun¬ tain in large, lharp, and ragged fragments, through which the river roars with hideous bellowing. In tins year 1731, a promontory on Sundmoer, called Rum- mersfield, that hung over Nordal Creek, fuddenly gave way, and plunged into the water ; which fwelled to fuch a degree, that the church of Strand, though half a league on the other fide of the bank, was overflowed : the creek however wras not filled up ; on the contrary, the fifhermen declare they find no difference in the depth, which is faid to exceed 900 fathoms. The remarkable rivers of Norway are thefe : The Nied, iffuing from Tydalen, on the borders of Sw'eden, runs weftward into the lake Selboe ; and afterwards, turning to the northward, pafles by the city of Dron* theim, to which it anciently gave the name of Nideros and Nidrofia: Sule Ely, that defeending from Sulefield, runs with a rapid courfe through Nordale into the fea ^ Gulen, which rifes near Sffarsfield in the north ; and running 20 leagues weftward, through Aalen, Hlotaa-. len, Storen, and Melhuus, difeharges itfelf into the fea about a league to the weft of Drontheim. In the year. 1344, this river buried iifelf under ground: from, whence it again burft forth with fuch violence, that the earth and ftones thrown up by the eruption filled the valley, and formed a dam ; which, however, was foon. broken and wafhed away |?y the force of the water. Divers churches, 48 farm houfes, with 250 perfons, were deftroyed on this occafion.—Otteroen, a large ri-. ver, taking its rife from the mountain Agde, runs about 30 leagues through Seeterdale and Efie, and difem- bogues itfelf into the cataraft of Wiland. The river Syre rifes near the mountain Lang, and winds its courfe through the vale of Syre into the lake of Lunde in the diocefe of Chriilianfand; thence it continues its way to. the fea, into which it difeharges itfelf through a narrow ftrait formed by two rocks. This contraction augments its impetuofity, fo that it fhootsdike an arrow into the fea, in which it produces- a very great agitation. Nid. and Sheen are two confiderable ravers, iffuing out of Tillemark. Their water-falls have been diverted, with. infinite labour, by canals and paffages cut through the. rocks, for the convenience of floating down the timber. Tyrefiord or Dramme, is in the neighbourhood of PIo- nifoffe,. NOR [ <5i ] NOR Norway, rufoffe, joined by two rivers from Oedale and Hade- -V ’ land, and diiembogues itfelf into tlie fea near Bragnefs. Loven rifes in the higheft part of Nummedal, and runs through Konlberg to the fea near Laurwig. Glaamen is the largelt river of Norway, diftinguilhed by the name of S/or Eivin, or the great river. It derives its origin from the mountain Dofre, from whence it winds all along the plains of Oefterdale and Soloe j then joins the Vorme, another confiderable river riling out of Mioes and Guldbrandfdale. Thefe being joined, tra- verfe the lake Oeyern ; and thence ilfuing, run on to Sarp near Frederickftadt. Norway abounds with frefh-water lakes •, the princi¬ pal of which are Ryfvand in Nordland, Snaafen, Selboe, the Greater and Leffer Mioes, Slirevand, Sperdille, Rand, Veftn, Saren, Modum, Lund, Norfoe, Huidfoe, Farifvand, and Oeyevand : all thefe are well Hocked with filh, and navigable for large veffels. Wars have been formerly carried on upon thefe inland feas 5 in fome of which are fmall floating iflands, or parcels of earth, with trees on them, feparated from the main land, and probably preferved in compact maffes by the roots of trees, fhrubs, and grals, interwoven in the foil. In the year 1702, the family feat of Borge, near Fre- derickftadt, being a noble edifice, with lofty towers and battlements, fuddenly funk into an abyfs 100 fathoms deep, which was inflantaneoufly filled by a piece of wa¬ ter 300 ells in length and about ha1f as broad. Four¬ teen perfims, with 200 head of cattle, periihed in this cataltrophe, which was occafioned by the river Glaamen precipitating itfelf down a water-fall near Sarp, and un¬ dermining the foundation. Of all the water-falls in Norway this of Sarp is the moil dangerous for its height and rapidity. The current drives 17 mills 5 and roars with fuch violence, that the water, being dafhed and comminuted among the rocks, rifes in the form of rain, where a beautiful rainbow may be always feen when the fun fhines. In ancient times this cataradl was made ufe of for the execution of traitors and other malefactors : they were thrown down alive, that they might be dalli¬ ed in pieces on the points of rocks, and die in a dread¬ ful commotion, analogous to thofe they had endeavour¬ ed to excite in the community. Great part of Norway is covered with fore ft s of wood, which conftitute the principal article of com¬ merce in this country. They chiefly confift of fir and pine, for which great fums are received from foreigners, who export an immenfe number of marts, beams, planks, . and boards. Befides, an incredible quantity is con- fumed at home in building lioufes, (hips, bridges, piles, moles, and fences 5 over and above the vaft demand for charcoal to the founderies, and fuel for domeltic ufes.—Nay, in fome places, the trees, are felled for no other purpofe but to clear the ground, and to be burn¬ ed into aflies for manure. A good quantity of timber is yearly exported from all parts of Norway ; but the chief exports arc from Drammen, Frederickfhall or Frederickftadt, Chriftiana, Skeen, Arendal, Chriftian- fand, Chriftian’s Bay, ^and Drontheim. The mafts and large beams are floated down the rivers, and the reft is divided into boards at the faw mills. Thefe works fupply a vaft number of families with a com¬ fortable fubfiftence.—A tenth part of all fawed tim¬ ber belongs to his Danifti majefty, and makes a confi- derable branch of hu revenue.. The foreits in Norway are fo vaft and thick, that the people feem to think there can never be a fcarcity of wood, efpecially as the foil is peculiarly adapted for the produftion of timber : they therefore deftroy it with a wafttful hand ; infomuch that more wood rots in Norway than is burned in the whole kingdom of Denmark. The beft timber grows in the provinces of Saltan, Helleland, Romidale, Guld¬ brandfdale, Oerterdale, Soloe, Valders, Hallingdale, Sog- nifiord, Tellemark, and the lordihip of Nedenes'. The climate of Norway is very different in different parts of the kingdom. At Bergen the winter is fo mo¬ derate, that the leas are always open arid pradficable both to mariners and filhermen, except in creeks and bays, that reach far up into the country towards File- field, when the keen north-eaft wind blows from the land. On the eaft fide of Norway, from the frontiers of Sweden to Filefield, the cold generally fets in about the middle of October with great feverity, and lafts till the middle of April; during which interval the waters are frozen to a very confiderable thicknefs, and the face of the country is covered with fnow. In the year 750c Swedes, who intended to attack Drontheim, pe- rilhed in the fnow on the mountain of Ruden or Tydel, which feparates Jempteland in Sweden from the diocele of Drontheim. A company of 200 Norwegian Hedge- men under Major Emahus, found them all frozen to death on the ridge of the mountain, where they had been overtaken by a ftorm accompanied with fnow, bail, and extreme cold. Some of thefe unhappy vidfims ap¬ peared fitting, fome lying, and others kneeling in a pof- ture of praying. They had cut in pieces their mulkcts, and burned the little wood they afforded.—The gene¬ rals Labarre and Zoega loft their lives j and of the whole corps, confiding originally of x0,000, no more than 2500 furvived this dreadful cataftrophe. The cold is ftill more intenfe in that part of Norway called Finmark, lituated in tire frigid zone near the po¬ lar circle. But if the winter is generally cold, the fum- mer is often exceflively hot in Norway. The rays of the fun are reverberated from the fides of the mountains fo as to render the weather clofe and fultry in the val¬ leys ; befides, the fun’s abfeuce below the horizon is fo ftiort, that the atmofphere and mountains have not time to cool. The beat is fo great, that vegetation is re¬ markably quick. Barley is fown, grows, ripens, and is reaped, in the fpace of fix weeks or two months. The longeft day at Bergen eonfifts of 19 hours j the fun rifing at half an hour after two, and letting at half an hour after nine. The Ihorteft day does not exceed fix hours ; for the fun rifes at nine in the morning, and fets at three in the afternoon.—In the beginning of the year the daylight increales with remarkable celerity y and, at the approach of winter, decreafes in the fame proportion. In fummer one may read and write at mid¬ night by the light of the Iky. Ch; iftian V. while he refided at Drontheim, ufed to fup at midnight without candles. In the diiiritt of Tromfen, at the extremity of Norway, the fun is continually in view at midfum- mer. It is leen to circulate day and night round the north pole, contracting its orbit, and then gradually- enlarging it, until at length it leaves the horizon. In the depth of winter, therefore, it is for fome weeks in- vifible y and all the light perceived at noon is a faint glimmering for about an hour and a half, proceeding from the refle&iun of the fun’s rays from the higheft Norway. mountains.- NOR [ 62 ] NOR Norway. mountains. But the inhabitants of thefe provinces are fupplied with other lights that enable them to follow their employments in the open air. The fky being ge¬ nerally ferene, the moonlhine is remarkably bright, and, being reflefted from the mountains, illuminates the valleys. They are alfo a flirted by the aurora bo¬ realis, which is very frequent in the northern parts of Europe. The air of Norway is generally pure and falubrious. On the fea coafts, indeed, it is rendered moift by va¬ pours and exhalations : but in the midland parts of the country, towards the mountains, the climate is fo dry, that meal may be kept for many years without being worm-eaten or damaged in the leaft. The inhabitants have no idea of ficknefs, except what is occartoned by excefles. It is faid, that in the vale of Guldbrand the inhabitants live to fuch extreme old age, that they be¬ come weary of life, and caufe themfelves to be removed to a lefs falubrious climate, whereby they may have a chance of dying the fooner. In confumptions, how¬ ever, the moilt air on the fea fide is found to be moft agreeable to the lungs in refpiration. Norway, being a mountainous country interfered by creeks, abounding with lakes, rivers, and fnow, muft be fubjeft to fre¬ quent rains ; and from fudden thaws the inhabitants are fometimes expofed to terrible difafters. Vaft mafles of fnow falling from precipices overwhelm men, cattle, boats, houfes, nay even whole villages. About two centuries ago, a whole parifli was covered and deftroyed by an immenfe mafs of fnow •, and feveral domeftic uten- fils, as fciflars, knives, and bafons, have been at differ¬ ent times brought to light by a rivulet that runs under the fnow, which has been gradually hardened and in- creafed by repeated frofts and annual acceffions. The winds that chiefly prevail on the weftern coaft are thofe that blow from the fouth ; whereas, on the other fide of Filefield, the winds that produce and con¬ tinue the hard frofts are always northerly. In the fum- mer, there is a kind of regular trade-wind on the coaft of Bergen. *In the forenoon the fea begins to be cooled with a wefterly breeze, which continues till midnight. Then the land breeze begins from the eaft, and blows till about ten in the morning. The coaft is likewife fubjeft to fudden fqualls and ftorms. Hurricanes fome¬ times rife at fea *, and in thefe latitudes the phenomenon called a water-fpout is not uncommon. One of thefe in the neighbourhood of Ferro is faid to have fucked up with the water fome lafts of herrings, which were afterwards dropped on Ivolter, a mountain 1200 feet high. The frefh water of Norway is not very light or pure; but on the contrary is generally turbid, and depofites a fediment of adventitious matter, being fometimes im¬ pregnated with ochre and particles of iron.—Neverthe- lefs it is agreeable to the tafte, and remarkably falubri¬ ous } as appears from the good health of the common people, ivho drink little or no other liquor. The foil of Norway varies in different places accord¬ ing to the fituation of rock or valley. The mountains, here, as in every other country, are bare and barren; but the earth walhed down from them by the rains en¬ riches and fertilizes the valleys. In thefe the foil gene- " rally confifts of black mould, fand, loam, chalk, and gravel, lying over one another in unequal ftrata, and fometimes in three or four fucceffions: the mould that lies uppermoft is very fine and mellow, and fit to non- Norway, rifti all forts of vegetables. There is alfo clay found in v'— different parts of this kingdom, of which the inhabitants begin to make earthen ware-, but bricks and tiles arfe not ufed in building. The face of the country is in many places deformed by large fwamps and marlhes, very dangerous to the traveller. Near Leeffoe in the diocefe of Chriftianfand, a wooden caufeway is extend¬ ed near a mile over a morafsj and if a horfe or any other animal ftiould make a falfe ftep, he will fink at once into the abyfs, never to rife again. In a cold country like Norway, roughened with rocks and mountains, interfperfed with bogs, and covered with forefts, we cannot expeft to find agriculture in perfec¬ tion. The ploughed lands, in refpedt to mountains, woods, meadows, and waftes, do not exceed the pro¬ portion of 1 to 80 ; fo that the whole country does not produce corn to maintain above half the number of its inhabitants. The peafants are difeouraged from the pra&ice of hufhandry by the frequency of accidents that feem peculiar to the climate. Even in the fruitful pro¬ vinces of Guldbrandfdale, Oefterdale, and Soloer, as well as in the other places, when the corn appears in the moft flouriflning condition, the whole hope of the har- veft is fometimes deftroyed in one night by a fudden froft that nips the blade and extinguilhes the vegetation. The kingdom is moreover vifited by fome unfavourable years, in which the fun feems to have loft his genial power ; the vegetables are ftunted the trees bud and bloom, yet bear no fruit *, and the grain, though it rifes, will yet produce nothing but empty ears and ftraw. This calamity, however, rarely occurs } and in general the cultivated parts of Norway yield plentiful crops of excellent rye, barley, and oats. The moft fruitful pro¬ vinces are Nordland, Inderbarre, and Numedale, in the diocefe of Drontheim ; Sognifiord and Vaas, in that of Bergen; Jedderen, Ryefylfk, Raabygdelag, and the lordftiip of Nedenes, in the diocefe of Chriftianfand ; Hedemark in the diocefe of Aggerhus ; Hadeland, Toten, Romerige, Ringerige, and Guldbrandfdale : thefe territories not only produce grain enough for their own confumption, but likewife fupport their neighbours, and even fupply part of Sweden.—Peafe are likewifd propagated in this country, together with wheat, buck¬ wheat, hops, hemp, and flax, but not to any confider- able advantage. The meadows are well fiored with pafturage for flieep and cattle, and the fields are produc¬ tive of thofe vegetables which are common in other northern countries. Within thefe 50 years the people of Norway have beftowed fome attention on the culture of gardens, which in former times was fo negledled, that the cities and towns were fupplied with leeks, cabbage, and roots, from England and Holland. At prefent, however, the Norwegians raife their own culinary and garden roots and vegetables, which thrive there as well as in any other country. The feurvy being a difeafe that prevails along the fea coaft, Nature has fcattcred upon it a variety of h-vbs efficacious in the cure of that diftemper-, fuch as angelica, rofe-wort, gentian, creffes, trefoil, forrel, feurvy-grafs, and a plant called crkK's grafs, that grows in great plenty on the iflands of Nord¬ land : from whence the people of the continent fetch away boat loads of it, to be preferved in barrels as a fuccedaneum for cabbage. There are alfo a few noxious vegetables little known in any country but Norway. NOR [ 63 ] NOR Norway. In G uldbrandfdale is a fpecies of grafs called felf nape ; the root of which is fo poifonous, that any bead which eats of it dies immediately, the belly burfting 5 nay, the carnivorous fowls that prey upon the carcafs ot the bead meet with the fame fate : children have been more than once poifoned by this root, which neverthelefs is fometimes ufed externally as an amulet for arthritic dii- orders. Another vegetable pernicious to the cattle is the Gramen oflifragum Norwegienfe, which is faid to mollifv the bones of the cattle which feed upon it. A- mong the noxious plants of Norway we may alfo reckon the igle-grafs, fatal to the fheep and goats ; the tour- grafs, which affedls horfes and cows with a fort of le¬ thargy } and the plant torboe, or hide-fpring, which produces nearly the fame effeft on horfes, but is not at all prejudicial to cows, dieep, or any ruminating animals. The herb turte, not unlike angelica, operates nearly in the fame manner : yet the bears are faid to feed upon it writh peculiar relith; and when their hair begins to fall off by feeding upon this plant, they cure themfelves by eating the fledi of animals. The common fruit trees thrive tolerably well in Nor¬ way, the inhabitants of which have plenty of cherries, apples, and pears. Some kinds of plums attain matu¬ rity ; which is feldom the cafe with grapes, apricots, and peaches. But even the apples and pears that ripen here are dimmer fruit; that which grows till the winter feldom coming to perfection. Great variety of agree¬ able berries is produced in different parts of this king- dod 5 fuch as the hagebar, a kind of does ; an infudon of which in wine makes a pleafant cooling liquor ; juni¬ per berries, corinths red and w'hite, foelbar or fun- berries, rafpberries, goofeberries, blackberries, draw- berries, &c. with many other fpecies that feem to be natives of Norway and Sweden. Among thofe are the tranaebar, the produce of the myrtillus repens, red and audere, found in the fpring in perfection under the fnow, and much relifhed by the reindeer ; crakebeer, refemb- ling bilberries, deemed a powerful antifcorbutic ; ager- beer, larger and blacker than bilberries, of a pleafant acid, ripened by cold, and ufed as cherries for an infu- fion in wine ; and finally tyltebeer, a red pleafant berry growing on a fiiort dem, with leaves like thofe of box ; they are plucked off by handfuls, and fent to Denmark to be preferved for the table, where they are eaten by way of deffert. Of the trees that grow wild in Norway, the prin¬ cipal are the fir and the pine. The fird yield an an¬ nual revenue of 1,000,000 of rixdollars, if we include the advantages refulting from the faw mills and the mads ; one of which lad has been kmnvn to fell for 200 rixdollars. The red fir tree, which grows on the moun¬ tains, is fo rich in turpentine as to be almod incorrupti¬ ble. Some of the houfes belonging to the Norway pea- fants, built of this timber, are fuppofed to be above 400 years danding. In Guldbrandfdale the houfe is dill to be feen danding in which King Olaf lodged five nights, above 700 years ago, when he travelled round the king¬ dom to convert the people to the Chriftian faith. Even 100 years after the trunk of the fir tree has been cut down, the peafants burn the roots for tar, which is a very profitable commodity. In the fens, the refin of the fir tree is by nature transformed into a fubdance which may be called Norway frankincenfe. The buds or pine aples of this tree, boiled in dale beer, make an Norw excellent medicine for the fcurvy j lefs unpleafant to 'r the tade, though as efficacious, as tar-water. The pine tree is more tall and beautiful than the fir, though in¬ ferior to it in drength and quality ; for which reafon the planks of it are fold at an inferior price, and the peafants wade it without remorfe. Norway likewife produces fome foreds of oak, which is found to be excellent for diip-building. Here alfo grow plenty of elm trees j the bark of which, being powdered, is boiled up with other food to fatten hogs, and even mixed by the poor among their meal 5 alfo the afh, from which the peafants didii a balfam ufed in certain dxforders, and which is ufed both externally and internally. Many other trees flouridi in this country, an enumeration of which would prove too tedious. Hazels grow here in fuch abundance, that 100 tons of the nuts are annually exported from Bergen alone. A great diverfity of dones is found in Norway, fome of which are of a furprifing figure. Several mountains confid chiefly of a brown pebble, which decays with- age ; nay, it fometimes diffolves, and drops into the fea, and the cement being thus loofened, a terrible difruption enfues. In fome places the gray and black pebbles are intermixed with iron, copper, lead, filver, and gold. The ground in certain didrifts is covered with the frag¬ ments of rocks that have been precipitated from the fummits of mountains, and broken by their fall into in¬ numerable Ihivers. Between 20 and 30 years ago, in the neighbourhood of Bergen, a man wras fuddenly over¬ whelmed with fuch a mafs, which formed a kind of vault around him. In this dreadful tomb he remained alive for feveral weeks. By his loud cries the place of his confinement was difcovered : but it was found impoflible to remove the huge dones by which he was inclofed. All that his friends could do for him was, to lower down meat and drink through fome crevices ; but at length the dones fell in, and crulhed him to death. In Norway are inexhaudible quarries of excellent marble, black, white, blue, gray, and variegated 5 to¬ gether with fome detached pieces of alabader, feveral kinds of fpar, chalk-done, gypfum, fand-done, mill- done, baking-done, date, talc, magnets, and fvvine-done, a produftion natural to Norway and Sweden, of a brown colour, fetid fmell, in texture refembling crydal, and deriving its name from a fuppofed efficacy in curing a didemper incident to fwine. Here alfo is found the amianthus or done-flax, of which incombudible cloth may be made. Norway, however, affords no flints, but plenty of pyrites, beautiful rock cryflals, gra¬ nites, amethyfts, agate, thunder-dones, and eagle- dones. Gold has formerly been found in fmall quan¬ tity in the diocefe of Chridianfand, and coined into- ducats. There is at prefent a very confiderable filver mine wrought at Konglberg on account and at the rifk. of his Danilh majedy : the ore is furprifingly rich, but interrupted in fuch a manner, that the vein is often lod. Many maffes of pure filver have been found ; and, among the red, one piece weghing 560 pounds, preferved in the royal mufeum at Copen¬ hagen. Such is the richnefs of thefe mines, that the annual produce amounts in value to a ton and a half in gold. About 5000. people are daily employ¬ ed, and earn their fubfidence, in thofe dupenduous works. N O R [ 64 ] N O R Norway, r.orks (a'). Other filver mines are profecuted at Jarlf- jjerg^ ljUt not to the fame advantage •, and here the ore is mixed avith lead and copper. In many parts of this country copper mines have been difeiWered but the •principal, and perhaps the richeft in all Europe, is at Jioraas, about 100 Englilh miles from Drontheim. This work yields annually about noo drip pounds of pure copper : the founderies belonging to it confume yearly about l-j.,000 lalls of coal, and 50Q fathoms of wood. The next in importance is the copper work at Lykken, about 20 miles from Drontheim. A third mine is carried on at Indfet or £)uickne, at the dif- tance of 30 miles from the fame place ; and here they precipitate the copper from its menftruum, by means of iron. There is a fourth copper work at Silboe, about 30 miles dillant from Drontheim, though the lead confiderable of the four. Other copper mines of lefs note are worked in different parts of the king¬ dom. Iron is dill in greater plenty, and was the fird metal wrought in this country. Many hundred thou- » land quintals are annually exported, chiefly in bars, and part of it in doves, pots, kettles, and cannon : the national profit arifing from this metal is edimated at 300,000 rixdollars. There is a fpecies called moor- iron, found in large lumps among the moraffes : of this the peafants make their own domedic tools and utenfils, fuch as knives, fcythes, and axes. I he lead found mixed in the filver ore is an article of fmall im¬ portance in Norway 5 yet fome mines of this metal have been lately opened in the didrifl of Soloer by the proprietors of the copper work at Oudal. A vi¬ triol work has been begun near Kongfberg : the mines yield great plenty of fulphur *, which, however, the Norwegians will not take the trouble to melt and de¬ purate, becaufe immenfe quantities are found at a cheaper rate in the idand of Iceland. Alum is found between the date flakes near Chridiana in fuch plenty, that works have been fet up for refining this mineral, though they have not yet brought it to any degree of tranfparency. His Danidi majedy has edablidied fait works in the peninfula of Valoe, about fix Englifh miles from Tonfberg, where this mineral is eXtra&ed in large quantities from the fea water. Befides the animals common to other countries, Nor¬ way is find to contain many of the uncommon and du¬ bious kind *, fuch as the kraken, mermaid, fea ferpent, &c. See thefe articles. Many Danidi, Englifh, Scotch, Dutch, and Ger¬ man families have now fettled in Norway j and indeed form no inconfiderable part of the trading people : but the original inhabitants are the defcendants of thofe fe¬ rocious Normanni, who haraffed almod all the coads of Europe with piratical armaments in the 8th, 9th, and 10th centuries. “ Our fird certain knowledge of the inhabitants of * At-a. this country (fays Pennant*) was from the defola- ■Zool. tion they brought on the fouthern nations by their Norway, piratical invalions. Their country had before thaty-'**' period the name of Nortmanland, and the inhabitants Narimans, a title which included other adjacent peo¬ ple. Great Britain and Ireland were ravaged by them in 845 ; and they continued theif invafion till they effefted the conqued of England, under their leader Canute the Great, They went up the Seine a3 far as Paris, burnt the town, and forced its weak monarch to purchafe their abfence at the price of fourteen thoufand marks. They plundered Spain, and at length carried their exeurfions through the Mediterranean to Italy, and even into Sicily. They ufed narrow veffels, like their ancedors the Sitones ; and, befides oars, added tiie improvement of two fails 5 and vidlualled them with failed provifions, bifeuit, cheefe, and beer. Their fliips were at fird fmall j but in after times they were large enough to hold 100 or 120 men. But the mul¬ titude of veffels was amazing. The deet of Harold Blaatand confided of 700. A hundred thoufand of thefe favages have at once failed from Scandinavia, fo judly dyled Officina gentium, aut eerie velut vagina na- tionwn. Probably neceffity, more than ambition, caufed them to difeharge their country of its exuberant num¬ bers. Multitudes were dedroyed ; but multitudes re¬ mained, and peopled more favourable climates. “ Their king, Olaus, was a convert to Chridianity in 994 5 Bernard an Englidiman had the honour of baptizing him, when Olaus happened to touch at one of the Scilly iffands. He plundered w ith great fpirit during feveral years; and in 1006 received the crown of martyrdom from his pagan fubjedls. But religious zeal fird gave the red of Europe a knowledge of their country and the fweets of its commerce. The Hanfe towns poured in their miffionaries, and reaped a tem¬ poral harved. By the year 1204, the merchants ob¬ tained from the wife prince Suer every encouragement to commerce ; and by that means introduced wealth and civilization into his barren kingdom. England by every method cherilhed the advantages refulting from an in- tercourfe with Norway, and Bergen was the emporium. Henry III. in 1217, entered into a league with its mo¬ narch Haquin ; by which both princes dipulated for free accefs for their fubjefts into their refpeftive king¬ doms, free trade, and fecurity to their perfons. In 1269, Henry entered into another treaty with Magnus ; in which it was agreed, that no goods Ihould be exported from either kingdom except they had been paid for ; and there is, beddes, a humane provifion on both ddes, for the fecurity of the perfons and effefts of the fubjefts who fhould differ diipwreck on their feveral coails.'” The inhabitants now fpeak the fame language that is. nfed in Denmark, though their original tongue is the dialeft now fpoken in Iceland. They profeis the Lutheran religion, under an archbidiop edablilhed at Drontheim, (a) Mr Coxe tells us, that he vidted thofe mines. They formerly, he fays, produced annually 70,000!. but at prefent yield little more than 50,600!. The expences generally exceed the profits ; and government pains only by the number of miners employed. The mines of cobalt, and the preparation of f ruffian blue, are much more produftive. The latter goes through 270 hands, and the number of men employed is 365. It is fuppofed, that, at this period (1793), it may produce to government a profit of 16,cool, a-year. NOR [65 K'orway. Drcmtheim, 'with four fuffragans ; namely, of Bergen, J Staffanger, Hammer, and Chriitiana. By the union of Calmar, the two kingdoms of Norway and Denmark were united under one monarch \ and then the people of both nations enjoyed conhderable privileges : but the Daniih government foon became abfolutej and Nor¬ way was ruled defpoticaliy by a viceroy, who redded in the capital, and prelided in the fupreme court, to which appeals wrere made from the fubordinate courts of judi¬ cature. A great change has, however, taken place iince the prefent amiable and accomplilhed prince of Denmark had part of the government j and more may be expected from his virtue and adiduity when the power (hall come wholly into his own hands. The Norwegians are generally well formed, tall, fturdy, and robult, brave, hardy, honed, hofpitable, and ingenious ; yet favage, raih, quarrelfome, and litigious. The fame character will nearly fuit the inhabitants of every mountainous country in the northern climates. Their women are well lhaped, tall, comely, remarkably fair, and obliging. The nobility of Norway have been chiefly removed by the kings of Denmark, in order to prevent faction and oppofition to the court ; or are long tago degenerated into the rank of peafants : feme fami¬ lies, however, have been lately raifed to that dignity. Every freeholder in Norway enjoys the right of primo¬ geniture and power of redemption ; and it is very ufual to fee a peafant inhabiting the fame houfe which has been poflefled 400 years by his anceflors. The odels-gads, or freehold, cannot be alienated by fale or otherwife from the right heir, called odels-mand: if he is not aole to redeem the edate, he declares his incapacity every 10th year at the fedions j and if he, or his heirs to the third generation, fliould acquire wealth enough for that purpofe, the poffeffor pro tempore mud reflgn his pof- feflion. The mountaineers acquire furpriling drength and dexterity by hard living, cold, laborious exercife, climb¬ ing rocks, Ikating on the fnow, and handling arms, which they carry from their youth to defend themfelves againd the wild beads of the fored. Thofe who dwell in the maritime parts of Norway exercife the employ¬ ments of fithing and navigation, and become very expert mariners. The peafants of Norway never employ any handi- craftfmen for neceffaries to themfelves and families : they are their own hatters, (hoemakers, taylors, tan¬ ners, weavers, carpenters, fmiths, and joiners : they are even expert at ihip-building 5 and fome of them make excellent violins. But their general turn is for carving in wood, which they execute in a furprifing manner with a common knife of their own forging. They are tauoht in their youth to wredle, ride, fwim, ikate, climb, (hoot, and forge iron. Their amufements confid in making verfes, blowing the horn, or playing upon a kind of gui¬ tar, and the violin : this lad kind of mufic they perform even at funerals. The Norwegians have evinced their valour and fidelity in a thoufand different indances. The country was always didrafted byintedine quarrels, which raged from generation to generation. Even the farmers dand upon their pun four couples danced before his Daniih majdty at Frederickfliall: their ages, when joined, exceeded 8co years. Neverthelcfs the Norwegians are fubjedt to va¬ rious difeafes j fuch as the fcab, the leprofy, the feurvy, the catarrh, the rheumatifm, gout, and epilepfy. The drefs of the Norway peafants confids of a wide loot© jacket made of coarfe cloth, with waidcoat and breeches of the fame. Their heads are covered with flapped hats, or caps ornamented with ribbons. They wear Ihoes without outer loles, and in the winter leathern bulkins. Fhey have likewile fnow Ihoes and long Ikates, with which they travel at a great pace, either on the land ox- ice. There is a corps of foldiers thus accoutred, who can outmarch the fwifted hories. I. he Norwegian pea¬ fant never wears a neckcloth, except on extraordinary occafions : he opens his neck and bread to the weather, and lets the fnow beat into his bofom. His body is girt round with a broad leathern belt, adorned with brafs plates, from which depends a brafs chain that fullains a large knife, gimlet, and other tackle. The women are dreffed in clofe laced jackets, having leathern girdles decorated with ornaments of iilvtr. 'They likewift wear- filver chains round their necks, to the ends of which are fixed gilt medals. Their caps and handkerchiefs are ai¬ med covered whh fmall plates of filver, brafs, and tin, large rings, and buttons. A maiden bride appears with her hair plaited, and, together with her clothes, hung full of fuch j tngling trinkets. The churches, public edifices, and many private houfes in Norway, are built of done \ but the people in general live in wooden houfes, made of the trunks of fir and pine tree laid upon each other, and joined by mortifes at the corners. I hefe are counted more dry, warm, and healthy, than done or brick buildings. In the whole diocefe of Bergen, one hardly fees a farm houfe with a chimney or window : they are generally lighted by a fquare hole in the top of the houfe, which lets in the light, and lets out the fmoke. In dimmer I this NOR [ 66 ] NOR Norway, this hole is left quite open : in the winter, it is covered Norwich.^ w]iat tjiey cau a Jiau; that is, the membrane of v lome animal, ftretched upon a wooden frame that fits the hole, and tranfmits the rays of light. It is fixed or removed with a long pole occafionally. Every perlon that enters the houie, upon bufinefs or courtlhip, takes hold of this pole, according to ancient cutlom. I he ceiling is about eight feet high in the middle ; and, be¬ ing arched like a cupola, the fmoke of the fire under¬ neath rolls about, until it finds a vent at the hole, which is called liiir. Under this opening Hands a thick table with benches, and a high feat at the upper end for the mailer of the family : he has likewife a fmall cupboard for his own ufe, in which he locks up his moll valuable effe&s. The boards of the roof are coated with the bark of the birch trees, which is counted incorruptible : this again is covered with turf, which yields a good crop of grafs for goats and Iheep, and is often mowed as hay by the farmer. The Norwegians carry on a confiderable trade with foreign nations. The duty on the produce of their own country exported, amounts annually to 100,000 rix- dollars. Thefe commodities are, copper wrought and unwrought 5 iron cad into cannon, ftoves, and pots, or forged into bars 5 lead, in fmall quantity; malls, tim¬ ber, deal boards, planks, marble, millllones, herring, cod, ling, falmon, lobilers, flounders, cow hides, goat fkins, feal fkins, the furs of bears, wolves, foxes, beavers, ermines, martens, Sec. down, feathers, butter, tallow, train oil, tar, juniper, and other forts of berries, and nuts*, fait, alum, glafs, vitriol, and pot allies. All other com¬ modities and articles of luxury the Norwegians import from different nations. The nature of the ground does not admit of much improvement in agriculture : never- thelefs, the farmers are not deficient in indullry and Ikill to drain marlhes, and render the ground arable and fit for paffure. Many are employed in grazing and breed¬ ing cattle: but a much greater number is engaged in felling wood, floating timber, burning charcoal, and ex- traSfing tar from the roots of the trees which have been cut down ; in the filver, copper, and iron mines 5 in the navigation and filhery. A confiderable number of peo¬ ple earn a comfortable livelihood by hunting, Ihooting, and bird catching. Every individual is at liberty to pur- fue the game, efpecially in the mountains and commons: therefore every peafant is expert in the ufe of fire arjns j and there are excellent markfmen among the mountains, who make ufe of the bow to kill thofe animals, whofe Ikins, being valuable, w'ould be damaged by the fhot of fire arms. Norway can produce above 14,000 excellent feamen. The army of this country amounts to 30,000 effe&ive men-, and the annual revenue exceeds 800,000 rixdollars. Nortvat Rat. See Mus, Mammalia Index. NORWICH, the capital of the county of Norfolk in England, fituated in E. Long. 1. 26. N. Lat. V2. 40. It is fuppofed to have had its name, which fighifies “ a eaftle to the north,” from its fituation in refpeSf of Caf- ter, the ancient Venta Icenorum, three or four miles to the fouth of it, out of whofe ruins it feems to have rifen. In its infancy, in the reign of Ethtldred, it was plun¬ dered and burnt by Sueno the Dane, when he invaded England with a great army. Afterwards it recovered and in the reign of Edward the Confeflbr wras a con- fidcrable place, having 1320 burghers. But it fuffered again much in the reign of William I. by being the feat Norwich, of a civil war, which Ralph earl of the Eail Angles " v"'11—1 raifed againil that king. So much w7as it impaired by the fiege it then underwent, that there wrere fcarce 560 burghers lett in it, as appears from Doomfday book. From that time forward it began by little and little to recover, efpecially after Bilhop Herbert tranflated the epifeopal fee hither from Thetford in the reign of Wil¬ liam Rufus in 1096 •, and built a beautiful cathedral, of which he himfelf laid the firll Hone, with this inferip- tion, Dominus Herbertus pofuit pritnam lapidem, in nomine Patris, Filii, et Spiritus Sanfti, Amen j i. e. “ Lord (Bilhop) Herbert laid the firll Hone, in ihe name of the Father, Son, and Holy Ghoft j” and by a licenfe from Pope Pafchal, declared it the mother church of Norfolk and Suffolk. After this, as Malmfbury has it, it became a town famous for merchandife and the number of inhabitants. Yet it wTas miferably harafftd in the reign of Henry II. by Hugh Bigod earl of Nor¬ folk, who was an adherent of Henry’s fon, called the junior king. In the t’me of Edward I. it was walled round by the citizens, who had prefented a petition to parliament for liberty to do it. Henry IV. allowed them, inllead of bailiffs, which they had before, to ele Novelty. NOV [7! Novelty, difagreeable ; for it is perfectly coniiflcnt, that we be delighted with an objett in one view, and terrified with it in another. A river in flood {welling over its banks, is a grand and delightful objccft ; and yet it may pro¬ duce no fmall degree of fear when we attempt to crols it : courage and magnanimity are agreeable ; and yet, when we view thefe qualities in an enemy, they ferve to increafe our terror. In the fame manner, novelty may produce two effects clearly diAinguiArable from each other : it may, diredtly and in itfelf, be agreeable ; and it may have an oppolite effeft indirectly, which is, to inlpire terror ; for when a new objedt appears in any degree dangerous, our ignorance of its powers and fa¬ culties affords ample fcope for the imagination to drefs it in the moft frightful colours. rIhe firft fight of a lion, for example,, may at the fame inflant produce two oppofite feelings, the pleafant emotion of wonder, and the painful paflion of terror : the novelty of the object produces the former diredlly, and contributes to the lat¬ ter indireclly. Thus, when the fubjedt is analyzed, we find that the power which novelty hath indirectly to inflame terror, is perfectly confiftent with its being in every circumftance agreeable. The matter may be put in the cleareft light, by adding the following circum- Itance. If a lion be firft feen from a place of fafety, the fpedtacle is altogether agreeable without the leait mixture of terror. If, again, the firft fight puts us within reach of that dangerous animal, our terror may be fo great as quite to exclude any fenfe of novelty. But this faCt proves hot that wonder is painful : it proves only, that wonder may be excluded by a more powerful paflion. Every man may be made certain from his own experience, that rvonder raifed by a new obfedt that is inoffenfive, is always pleafant; and with refpedt to often five objedls, it appears, from the fore¬ going dedudlion, that the fame muff hold as long as the fpedlator can attend to the novelty. Whether farprife be in itfelf pleafant or painful, is^a queftion not lefs intricate than the former. It is certain that furprife inflames our joy when unexpedtedly we meet with an old friend } and not lefs our terror when w7c Humble upon any thing noxious. To clear that queftion, the firft thing to be remarked is, that in fome xnftances an unexpected object overpowers the mind, fo as to produce a momentary ftupefadtion : where the ob- jedt is dangerous, or appears fo, the fudden alarm it gives, without preparation, is apt totally to unhinge the mind, and for a moment to fufpend all its faculties, even thought itfelf-, in which ftate a man is quite helplefs : and if he move at all, is as like to run upon the danger as from it. Surprife carried to fuch a height, cannot i ] NOV be either pleafant or painful becaufe the mind, during Novelty, fuch momentary ftupefadlion, is in a good meafure, if v““ not totally, infenfihle. If we then inquire for the charadler of this emotion, it muft be where the unexpedted objedl or event produ- ceth lefs violent effedls. And while the mind remains fenfible of pleafure and pain, is it not natural to fuppofe, that furprii'e, like wonder, fliould have an invariable charadter ? It would appear, however, that furprife has no invariable charadler, but afiumes that of the objedl which raifes it. Wonder being an emotion invariably raifed by novelty, and being diftinguifbable from all other emotions, ought naturally to poffefs one conftant charadler. The unexpedted appearance of an objedl, feems not equally entitled to produce an emotion diftin- guiftiable from the emotion, pleafant or painful, that is produced by the objedl in its ordinary appearance : the effedl it ought naturally to have, is only to fwell that emotion, by making it more pleafant or more painful than it commonly is. And that conjecture is confirmed by experience, as well as by language which is built upon experience : when a man meets a friend unexpect¬ edly, he is faid to be agreeably furprifed } and when he meets an enemy unexpedtedly, he is faid to be difagree- ably furprifed. It appears, then, that the foie effedl of furprife is to fwell the emotion raifed by the objedl. And that eft'edl can be clearly.explained : a tide of con- nedled perceptions glide gently into the mind, and pro¬ duce no perturbation ^ but an object breaking in unex- pedledly, founds an alarm, roufes the mind out of its calm ftate, and diredls its whole attention to the objtdl, which, if agreeable, becomes doubly fo. Several cir- cumftances concur to produce that effedl : on the one hand, the agitation of the mind and its keen attention prepare it in the moft effedlual manner for receiving a deep impreffion : on the other hand, the objedl, by its fudden and unforefeen appearance, makes an impreflion, not gradually as expedled objedls do, but as at one ftroke with its whole force. The circumftances are precifely fimilar where the objedl is in itfelf difagrec- able (a). The pleafure of novelty is eafily diflinguiflied from that of variety : to produce the latter, a plurality of ob¬ jedls is neceffary ; the former arifes from a circumftance found in a fingle objedl. Again, Where objedls, whe¬ ther co-exiftent or in fucceflion, arc fufiiciently diverfi- fied, the pleafure of variety is complete, though every fingle objedl of the train be familiar ; but the pleafure of novelty, diredlly oppofite to familiarity, requires no diver fification. There are different degrees of novelty, and its effedls are (a) What Marefchal Saxe terms le coeur humain, is no other than fear occafioned by furprife. It is owing to that caufe that an ambufh is generally fo deftruaive : intelligence of it beforehand renders it perfeaiy harmlefs. The Marefchal gives from Cseflir’s Commentaries two examples of what he calls le coeur huniain. At the fiege of Amiens by the Gauls, Cajfar came tip with his army, which did not exceed 7000 men ; and began to entrench himfelf in fuch hurry, that the barbarians judging him to be airaid, attacked his entrenchments with great fpirit. During the time they were filling up the ditch, he iffued out with his cohorts, and Dy attacking them unexpectedly ftruck a panic that made them fly with precipitation, not a fingle naan offered to make a Hand. At the fiege^of Alefia, the Gauls infinitely fuperior in number, attacked the Roman lines of circumvallation, in order to raife the liege. Ciefar ordered a body of bis rnen to march out filently, and to attack tnem on the one flank, while he with another body did the fame on the other flank. The furprile ot being attacked when they expected a defence oiuy, put the Gauls into diforder, and gave an eafy victory to Caefar. A NOV [ 79 J NOV Novelty, are In proportion. The loweft degree Is found in ob- 'V"—''je&s furveyed a fecond time after a long interval j and that in this cafe an objedt takes on fome appearance of novelty, is certain from experience : a large building of many parts varioufly adorned, or an extenfive field em- bellifhed with trees, lakes, temples, Itatues, and other ornaments, will appear new oftener than once : the me¬ mory of an objedt fo complex is foon loft, of its parts at leaft, or of their arrangement. But experience teaches, that, even without any decay of remembrance, abfence alone will give an air of novelty to a once familiar ob- jedt $ wrhich is not furprifing, becaufe familiarity wears off gradually by abfence : thus a perfon with whom we have been intimate, returning after a long interval, ap¬ pears like a new acquaintance. And diftance of place contributes to this appearance, not lefs than diftance of time : a friend, for example, after a fhort abfence in a remote country, has the fame air of novelty as if he had returned after a longer interval from a place nearer home : the mind forms a connexion between him and the remote country, and bellows upon him the fingula rity of the objedts he has feen. For the fame reafon, when two things equally new and lingular are prefented, the fpedlator balances between them ; but when told that one of them is the produdf of a diftant quarter of the world, he no longer hefitates, but clings to it as the more fingular : hence the preference given to foreign luxuries, and to foreign curiofities, which appear rare in proportion to their original diftance. I he next degree of novelty, mounting upward, is found in objedfs of which we have fome information at fecond hand 5 for defeription, though it contribute to familiarity, cannot altogether remove the appearance of novelty when the objedt itfelf is prefented : the firft fight of a lion occafions fome wonder, after a thorough acquaintance with the correcteft pi&ures and Itatues of that animal. A new objedf that bears fome diftant refemblance to a known fpecies, is an inftance of a third degree of no¬ vel? y : a ftrong refemblance among individuals of the fame fpecies, prevents almoft entirely the effedt of no- V' lty, unlefs diftanee of place or fome other circum- ftance concur ; but where the refemblance is faint, fome degree of wonder is felt, and the emotion riles in pro¬ portion to the faintnefs of the refemblance. 'i'he higheft degree of wonder arifeth from unknown objedts that have no analogy to any fpecies we are ac¬ quainted with. Shakefpuare in a limile introduces that fpecies of novelty : As glorious to the fight As is a winged meflenger from heaven Unto the white up-turned wond’ring eye Of mortals, that fall back to gaze on him, Novelty. When he beftrides the lazy pacing clouds, u-—y—. And fails upon the bofom of the air. Romeo and Juliet, One example of that fpecies of novelty deferves pecu¬ liar attention •, and that is, when an objedt altogether new is feen by one perfon only, and but once. Thefe circumftances heighten remarkably the emotion : the Angularity of the fpedlator concurs rtith the Angu¬ larity of the objedt, to inflame wonder to its higheft pitch. In explaining the effects of novelty, the place a be¬ ing occupies in the fcale of exiftence, is a circumftance that mult not be omitted. Novelty in the individuals of a low7 clafs is perceived with indifference, or with a very flight emotion : thus a pebble, however lingular in its appearance, fearcely moves our wonder. The emo¬ tion rifes with the rank of the objedt j and, other cir¬ cumftances being equal, is ftrongeft in the higheft order of exiftence ; a Itrange infedt affedts us more than a ftrange vegetable j and a ftrange quadruped more than a ftrange iufedt. However natural novelty may be, it is a matter of experience, that thofe who relilh it the molt are careful to conceal its influence. Love of novelty, it is true, prevails in children, in idlers, and in men of lhallow underftanding : and yet, after all, why Ihould one be alhamed of indulging a natural propenfity ? A diftinc- tion will afford a fatisfadtory anfwer. No man is alham¬ ed of curiofity when it is indulged to acquire knorv- ledge. But to prefer any thing merely becaufe it is new, Ibows a mean tafte which one ought to be aflia- med of: vanity is commonly at the bottom, which leads thofe who are deficient in tafte to prefer things odd, rare, or fingular, in order to diftinguilh them- felves from others. And in fadt, that appetite, as above mentioned, reigns chiefly among perfons of a mean tafte, who are ignorant of refined and elegant pleafures. Of this tafte we have fome memorable inftances in men of the higheft and the belt education. Lucian tells the following ftory of Ptolemy I. which is as dif- graeeful to him, as honourable to his fubjedts. This prince had ranfaeked the world for two curiofities j one was a camel from Badtria all over black ; the other a man, half black half white. Thefe he prefented to the people in a public theatre, thinking they would give them as much fatisfadtion as they did him ; but the black monlter, inftead of delighting them, affright¬ ed them ; and the party-coloured man raifed the con¬ tempt of fome and the abhorrence of others. Ptolemy, finding the Egyptians preferred fymmetry and beauty to A third may be added not lefs memorable. In the year 8q6, an obftinate battle was fought between Xamire venfj ,Le°An T Ab,d()UlnIhm™ the Mooriai k'ms ^ Spain. After a very long conflidt the night only pre- vented the Arabians from obtamtng a complete vidtory. The king of Leon, taking advantage of The darknefs retreated to a neighbouring lull, leaving the Arabians matters of the field of battle.8 Next morning, perceiving • ' U C0U ,nut maiIJlt?!n hls Placc f°r want °f provifions, nor be able to draw off his men in the face of a vidtoT 16 rangCd i'S T” m fd,e!.' of and, without lofing a moment, marched to attack the enemy, fi.rr 1 1 all ^Onqfr-Or d'e* r,‘e Arabians, aftomfhed to be attacked by thofe who were conquered the night be- out almoft drawing IT’ ‘ t0 aftoulfhment>lhe Pauic tmiverfal, and they all turned their backs with- } NOV [ 80 ] NOV ^vovjce to tlio vnoil ^ftonifhing productions of art or nature ^ it. without' them, wifely removed his two enormous trifles BNnvl - out of fight j the neglected camel died in a little ■ ^ 1L time, and the man he gave for a fong to the mufician Thefpis. One final caufe of wonder, hinted above, is, that this emotion is intended to flimulate our curiofity. An¬ other, fomewhat different, is, to prepare the mind for receiving deep impreflions of new objeCts. An acquaint¬ ance with the various things that may affeCt us, and with their properties, is eflential to our well-being nor will a flight or fuperficial acquaintance be fufficient; they ought to be fo deeply engraved on the mind, as to be ready for ufe upon every occaflon. Now, in order to a deep impreflion, it is wifely contrived, that things fhould be introduced to our acquaintance with a certain pomp and folemnity produClive of a vivid emotion. When the impreflion is once fairly made, the emotion of novelty being no longer neceflary, vanilheth almoft inftantaneoufly j never to return, unlefs where the im¬ preflion happens to be obliterated by length of time or other means ; in which cafe the fecond introduClion hath nearly the fame folemnity with the firft. Defigning wifdom is nowhere more legible than in this part of the human frame. If new objefts did not affedt us in a very peculiar manner, their impreflions would be fo flight as fcarce to be of any ufe in life ; on the other hand, did objeCts continue to affeft us as deeply as at firft, the mind would be totally engrof- fed with them, and have no room left either for a&ion or refleClion. The final caufe of furprife is ftill more evident than of novelty. Self-love makes us vigilantly attentive to felf-prefervation •, but felf-love, which operates by means of reafon and refleClion, and impels not the mind to any particular objeCf or from it, is a principle too cool for a hidden emergency ; an objeCt breaking in unexpectedly, affords no time for deliberation ; and in that cafe, the agitation of furprife comes in feafon- ably to roufe felf-love into aCtion ; furprife gives the alarm *, and if there be any appearance of danger, our whole forge is inftantly fummoned to flmn or to pre¬ vent it. NOVELLARA, a handfome town of Italy, and capital of a {mall diftriCl of the fame name, with a hand¬ fome caftle, where their fovereign refides. E. Long. 10. 37. N. Lat. 45. 50. NOVEMVIRI, nine magiftrates of Athens, whofe government lafted but for one year. The firft of whom was called arc/ion, or prince j the fecond bq/tlius, or king ; the third polemarckus, or general of the army : the other fix were called thefmothetce, or lawgivers. They took an oath to obferve the laws j and in cafe of failure, obliged themfelves to beftow upon the common¬ wealth a ftatue of gold as big as themfelves. Thofe who difeharged their office with honour, were received into the number of the fenators of Areopagus. NOVI, a town of Italy, in the territory of Genoa, on the confines of the Milanefe. It was taken by the Piedmontefe in 1746. E. Long. 8. 48. N. Lat. 44. 45. Non Bazar, a confiderable town of Turkey in Eu¬ rope, and in Servia, near the river Orefco. E. Long. 20. 24. N. Lat. 43. 25. NOVICE, a perfon not yet {killed or experienced Novic* in an art or profeflion. _ - NovJL d In the ancient Roman militia, novicn, or novitii, were \y click?' the young raw foldiers, diftinguiftred by this appellation u from the veterans. In the ancient orders of knighthood, there were no¬ vices or clerks in arms, who went through a kind of apprenticelhip ere they were admitted knights.—See Knight. Novice is more particularly ufed in monafteries for a religious yet in his, or her, year of probation, and who has not made the vows. In fome convents, the fub-prior has the diredlion of the novices. In nunneries, the novices wear a w hite veil; the reft a black one. NOVICIATE, a year of probation appointed for the trial of religious, whether or no they have a voca¬ tion, and the neceflary qualities for living up to the rule ; the obfervation w hereof they are to bind them¬ felves to by vow. The novitiate lafts a year at leaft j in fome houfes more. It is efteemed the bed of the civil death of a novice, who expires to the world by profeflion. NOVIGRAD, a fmall but ftrong town of Upper Hungary, capital of a county of the fame name, with a good caftle, feated on a mountain near the Danube. E. Long. 18. 10. N. Lat. 40. 50. Novigrad, a fmall but ftrong town of Dalmatia, with a caftle, and fubjeft to the Turks *, feated on a lake of the fame name, near the gulf of Venice. E. Long. 16. 45. N. Lat. 44. 30. _ NOVIGRAD, a very ftrong place of Servia, fiibjeft to the Turks 5 feated near the Danube. E. Longvib. 5. N. Lat. 45. 5. N0V10DUNUM (Cfefar), a town of the ^dui, commodioufly feated on the Liguris : the Nivernum of Antenine. Now Nevers in the Orleannois, on the Loire.—A fecond Noviotlunum of the Aulerci Dia- blintes, in Gallia C^ltica, (Antonine) j called Novio- dunum (Ptolemy), and Noningentutn Rotrudum by the moderns : Nogente le Rotrou, capital of the duchy of Perche.—A third of the Eituriges, (Ciefarj : Now Nueve fur Baranion; a village 15 miles to the north of Bourges, towards Orleans.—A fourth, of Moefia Inferior, (Ptolemy), fituated on the Ifter : now Nivorz, in Beflarabia.—A fifth, of Pannonia Superior, (An¬ tonine) 5 now Gurhfeld in Carinthia.—A fixtb, Novio- dunum SueJJionum, the fame with Augujla Sueffionutiu— A feventh, Noviodunwn of the Veromandux in Gallia Belgica, (Ccefar) : now Noyon in the Ifle of France, on the borders of Picardy. NOUN, fee Grammar, N° 7. j and Chapter L in toto. NOVOGOROD WELICKI, Great Novgorod, ac¬ cording to Mr Coxe, is one of the moft ancient cities in Ruflia. It was formerly called Great Novogorod, to diftinguifh it from other Ruffian towns of a fimilar ap¬ pellation ; and now prefents to the attentive and intel¬ ligent traveller a ftriking inftance of fallen grandeur. According to Neftor, the earlieft of the Ruffian hi- ftorians, it was built at the fame time with Kiof, namely, in the middle of the 5th century, by a Sela- vonian horde, who, according to Procopius, iflued from the banks of the Volga, {ts antiquity is dearly • proved NOV [ Novogcrrod proved by a paffage in the Gothic hidorian Jornandes, Welicki. }n YvrJjleh it is called Civitas Nova, or new town. We f have little infight into its hiftory before the 9th cen¬ tury, when Ruric the firft great duke of Rufiia reduced it, and made it the metropolis of his valt dominion. The year fubfequent to his death, which happened in £79, the feat of government was removed, under his fon Igor, then an infant, to Kiof; and Novogorod con¬ tinued, for above a century, under the jurifdiction of governors nominated by the great dukes, until 970, when Svatoflaf, the fon of Igor, created his third fon Vladimir duke of Novogorod: the latter, fucceeding his father in the throne of Ruifia, ceded the town to his fon Yarollaf, who in 1036 granted to the inhabitants very confiderable privileges, that laid the foundation of that extraordinary degree of liberty which they after¬ wards gradually obtained. From this period Novogorod was for a long time governed by its own dukes : thefe fovercigns were at firft fubordinate to the great dukes, who refided at Kiof and Volodinlir ; but afterwards, as Ithe town increafed in population and wealth, they gra¬ dually ufurped an abfolute independency. Its indepen¬ dency, however, was not perpetual. It continued, in¬ deed, in a flouriihing ftate until the middle of the 15th century : but the great dukes of Rufiia, whofe anceftors had reigned over this town, and who ftill retained the title of dukes of Novogorod, having transferred their re- fidence from Kiof to Volodimir, and afterwards to Mof- cow, laid claim to its feudal fovereignty ; a demand 1 which the inhabitants fometimes put off by compofition, fometimes by refiftance, but were fometimes compelled to acknowledge. At length, however, the great duke became abfolute fovereign of Novogorod, though the -oftenfible forms of government were ftill preferved. It even then, however, continued to be the largeft and molt commercial city of Rufiia; a proof of which we have as late as the year 1554, from the following de- feription of Richard Chancellor, who paffed through it in 1554 on bis way to Mofcow. “ Next unto Mofcow, the city of Novogorod is reputed the chiefeft of Ruflia ; for although it be in majefty inferior to it, yet in greatnefs it goeth beyond it. It is the chiefeft and greateft mart town of all Mufcovy ; and albeit the emperor’s feat is not there, but at Mofcow, yet the commodioufnefs of the river, falling into that gulf which is called Sinus Finnicus, whereby it is well frequented by merchants, makes it more famous than Mofcow itfelf.” An idea of its population during this period, when compared with its prefent declined ftate, is manifeft from the fa£I, that in I508 above 15,000 perfons died of an epidemical difwder ; more than double the number of its prefent inhabitants. In its moft flouriihing condition it contained at leaft 400,000 fouls. Its ruin was brought on by Ivan Va- lilievitch II. and completed by the foundation of Pe- terlburgh. The prefent town is furrounded by a ram¬ part of earth, with a range of old towers at regular diftances, forming a circumference of fcarcely a mile and a half; and even this inconfiderable circle in¬ cludes much open fpace, and many houfes which are not inhabited. As Novogorod was built after the manner of the ancient towns in this country, in the Afiatic ftyle, this rampart, like that of the Semlaino- gorod at Mofcow, probably enclofed feveral interior Vol. XV. Part I. 81 ] N O Y circles. Without it was a vaft extenfive fuburb, which Novogorai reached to the diftance of fix miles, and included with- ^e!lcki in its circuit all the convents and churches, the ancient j^0y0n ducal palace and other ftruffures, that now make a ■ -■ ^ , fplendid but lolitary appearance, as they lie Icattercd in the adjacent plain. Novogorod ftretches on both fides of the Volkof, a beautiful river of confiderable depth and rapidity, and „ fomewhat broader than the Thames at Windfor. This river feparates the town into two divifions, the trad¬ ing part, and the quarter of St Sophia, which are unit¬ ed by means of a bridge, partly wooden and partly brick. NOVOGOROD Weiicki, a province of Mufcovy, bound¬ ed on the north by Ingria ; on the eaft by part of the duchy of Belozero, and that of Tuera, which alfo bounds it on the fouth, with the province of Rzeva ; and on the weft by Plefcow. It is full of lakes and forefts ; however, there are fome places which produce corn, flax, hemp, honey, and wax. NOVOGOROD Serpjhoi, a ftrong town of the Ruffian empire, and capital of a province of Siberia of the fame name, featedon the river Dubica, in E. Long. 33. 20. N. Lat. 52. 30. NOVOGORODECK, a town of Lithuania, and capital of a palatinate of the fame name. It is a large place, and fituated in a vaft plain, in E. Long. 25. 30, N. Lat. 53. 45. NOURISHMENT. See Nutrition. Nourishment of Vegetables. See Agriculture . Index. NO WED, in Heraldry, fignifies u knotted,” from the Latin nodatus ; being applied to the tails of fuch creatures as are very long, and fometimes reprefented in coat armour as tied up in a knot. NOX, in fabulous hiftory, one of the moft ancient deities among the heathens, daughter of Chaos. From her union with her brother Erebus, fhe gave birth to the Day and the Light. She was alfo the mother of the Parcae, Hefperides, Dreams, of Difcord, Death, Mo- mus, Fraud, &c. She is called by fome of the poets the mother of all things, of gods as well as of men ; and fhe was worfhipped with great folemnity by the ancients. She had a famous ftatue in Diana’s temple at Ephefus. It was ufual to offer her a black fheep, as fhe was the mother of the Furies. The cock was alfo offered to her, as that bird proclaims the approach of day during the darknefs of the night. She is re¬ prefented as mounted on a chariot, and covered with a veil befpangled with ftars. The conftellations gene¬ rally Avent before her as her conftant meffengers. Some¬ times fhe is feen holding tAvo children under her arms; one of which is black, reprefenting Death, and the other white, reprefenting Sleep. Some of the moderns have defcribed her as a woman veiled in mourning, and croAvn- ed with poppies, and carried on a chariot draivn by oavIs and bats. NO YON, a toAvn of France, fituated on the decli¬ vity of a hill on the rivulet Vorfe, which at a quarter of a league’s diftance falls into the Oyfe, in the department of Oyfe, in E. Long. 3. o. N. Lat. 49. 38. about 66 miles north-eaft of Paris. It is an ancient place, being the Noviodunum Belgarum oi the Latins. It is a pretty large city, and is well fituated for inland trade, Avhich confifts here in Avheat and oats, Avhich they fend to L Parij. Noyon il Nuba. NUB [8 Paris. They have alfo manufaftories of linen cloths, lawns, and tanned leather. There are eight pariflies in , it, two abbeys, and feveral monafteries of both fexes. It is the fee of a biihop, fuffragan to the metropolitan of Rheims ; he has the title of count and peer of France, and his income is faid to amount to about 15,000 livres per annum. The principal buildings are the epifcopal palace, a cloifter where the canons of the cathedral dwell, and the town-houfe. The latter is regularly built in a large fcjunre, in the middle of which there is a fountain, where the water conveyed to it from a neighbouring mountain runs continually through three conduits, and is received in a large bafon built of very hard done. They have alfo many other fountains, feveral market places, and two public gardens. Noyon is particularly remarkable for the birth of the famous John Calvin, who was born here on the 10th of July 1502, and died at Geneva the 27th of Pvlay 1564. NUAYHAS, the Ague Tree 5 a name given by the Indians to a fort of bamboe cane, the leaves of which falling into the water, are faid to impregnate it with fuch virtue, that the bathing in it afterwards cures the ague. iL hey ufe alfo a decodlion of the leaves to diffolve coagulated blood, giving it inter¬ nally, and at the fame time rubbing the bruifed part externally with it. It is faid that this plant bears its flowers only once in its life ; that it lives 60 years be¬ fore thofe make their appearance 5 but that when they begin to (how themfelves, it withers away in about a month afterwards ; that is, as foon as it has ripened the feed. There feems to be fomething of fidlion m the account of many other particulars relating to this tree in the IIortus Ma/abaricus ,* but it feems certain, that the length of the ftalks, or trunk, muft be very great : for, in the gallery of Leyden, there is pre- ferved a cane of it 28 feet l°ng 5 and another not much Ihorter in the Afhmolean mufeum at Oxford, and which is more than eight inches in diameter : yet both ' thefe appear to be only parts of the whole trunk, they being nearly as large at one end as at the other. NUBA, a race of black Pagans, in the neighbour¬ hood of Sennaar, of whom v^e know nothing but what we have learned from Mr Bruce. That celebrated tra¬ veller paflfed a day or two among them, in his wray from Abyflinia } and he tells us, that they are all fol- diers of the Mek or king of Sennaar, cantoned in vil¬ lages, which to the diftance of four or five miles fur- round the capital. They are not the aborigines of that part of Africa } but “ are either purchafed or taken by force from Fazuclo, and the provinces to the fouth upon the mountains Dyre and Tegla.” Though the flaves of a cruel and treacherous mafter, Mr Bruce re- prefents them as a gentle, honeft, and hofpitable people ; and he fays exprefsly, that on a journey he had feldom palled a more comfortable night, than one in which he took refuge from a llorm in a village of thofe Nuba. He had a good (upper, and a clean neat hut to fleep in, while fome of the Nuba watched for him all night, and took care of his beads and his baggage. “ Having fettlements and provifions given them by the govern¬ ment of Sennaar, as alfo arms put into their hands, they never wifh to defert, but live a very domeftic and fober life, and are a much gentler fort of negro than their mafters.” (See Sennaar). Though the 2 ] NUB eftablifhed religion of Sennaar is that of Mahomet, the government has never attempted to convert the Nuba. On the contrary, a certain number of Pagan prielts is maintained for them in every village, who have fol- diers in pay to aflift them in the affairs of their religion. This is a very lingular inflance of toleration among Mahometans, and what we fliould little have expedled from fuch barbarous and fanguinary wretches as thofe who have the fupreme power in Sennaar, had not our obferving traveller informed us, that thefe men them¬ felves know almoft nothing of the religion which they profefs, and are in their hearts rather Pagans than Ma¬ hometans. The idolatry of the Nuba is defcribed as a mixture of Sabiifm and flatue worfhip : but what is very un¬ common, their worfhip is chiefly paid to the moon, while they pay no attention to the fun either rifmg or Nuba, fetting, advancing to the meridian or receding from it. It is an old obfervation, that the worfhip of every people is tinflured by their natural difpofitions ; and this is verified in the Nuba. “ That their worfhip is per¬ formed with pleafure and fatisfaclion, is obvious (fays our author) every night that the moon fbines. Coming out from the darknefs of their huts, they fay a few words upon feeing her brightnefs, and teftify great joy, by motions of their feet and hands, at the firll appearance of the new moon.” I his is juft what we fliould have expe&ed from their gentlenefs and hofpk tality. They worfhip likewife a tree and a ftone ; but our author could never difcover what tree or ftone 5 only he learned that neither of them exifts in Sennaar. but in the country where the Nuba are born. Such of them as are natives of the villages where he faw them, become, like their mafters, nominal Mahometans.— The reft praftife the idolatrous worfhip of their ancef- tors, and arp much under the influence of their priefts, from fear rather than from affedfion. They are im¬ moderately fond of fwine’s flefli, and maintain great herds of fmall hogs, marked with black and white fpots. Few of the Nuba advance higher than to be foldiers and officers in their own corps j and the Mek main¬ tains about 12,000 of them near Sennaar to keep the Arabs in fubjedlion. In a climate fo violent as that which tjiey inhabit, there is very little need of fuel 5 and it is happy for them that fuch is the cafe, for in the whole country there is not a Angle tree, or turf, or any thing refembling it. They do not, however, “ eat their meat raw like the Abyflinians 5 but with the ftalk of the dora or millet, and the dung of ca¬ mels, they make ovens under ground, in whicli they roaft their hogs whole, in a very cleanly manner, keep¬ ing their fkins on till they are perfedlly baked. They have neither flint nor fteel with which to light their fire at firft ; but do it in a manner ftill more expedi¬ tious, by means of two flicks, brought, we are led to think, from Sennaar, and there picked out of the river when flooded. They make a fmall hole in one of thefe flicks, and point the other : then laying the former in a horizontal pofition, they apply the point of the latter to the hole •, and, turning the perpendicular flick be¬ tween their hands, as we do a chocolate mill, both flicks take fire and flame in a moment •, fo perfeflly dry and prepared to take fire is every thing there on the furface of the earth,” NUBECULA,. NUB [ 83 ] NUB Nubecula, Nubia. NUBECULA, Little Cloud, in Medicine, a term fometimes ufed for a difeafe in the eye, wherein objefts ^—v ' appear as through a cloud or mill. The nubecula feems to arife from certain grofs par¬ ticles detained in the pores of the cornea, or fwimming in the aqueous humour, and thus intercepting the rays of light. Nubecula, or Nubes, is alfo ufed for what is other- wdfe called albugo. See Albugo. Nubequla is ufed like wife for a matter in form of a cloud, fufpended in urine. NUBIA, a kingdom of Africa, bounded on the north by Egypt, on the call by the Red fea and part of Abydinia, on the weft by the kingdoms of Tagua, Gaoga, and the defert of Gerharn. The river Nile runs through it ; on the banks of which, and thofe of the other rivers, it is pretty fruitful, but in other places barren, fandy, and in want of water. To the weft of the Nile is the defert of Bahouda, which is five days journey over, being the ufual road from Egypt to Abyffinia. Money is of no ufe in this country in the way of trade, it being all carried on by way of ex¬ change. Their bread and drink is made of a fmall round feed, called dor a or fej}\ which is very ill tailed. Their houfes have mud walls,, being very low, and covered with reeds. The habit of the better fort is a veft without fleeves; and they have no coverings for their heads, legs, and feet. The common people wrap a piece of linen cloth about them, and the children go quite naked. They are a ftupid debauched fort of people, having neither modefty, civility, nor religion, though they profefs to be Mahometans.—The produc¬ tions of this country are gold, elephants teeth, civet, and fandal wood j and they fend a great many Haves in¬ to Egypt. The principal towns known to the Euro¬ peans are Dangola and Sennaar. It is famous for a race of horfes the moft powerful and docile in the world. Thefe animals are generally about fixteen hands high 5 and by Mr Bruce, who has given the moft fcientific account of them, they are laid to be the breed which was introduced into Nubia at the Saracen conqueft, and has been preferved un¬ mixed to this day. Our author reprelents this as a much nobler animal than the Arabian horfe. “ What * Travels, figure (fays he *) the Nubian horfe would make in vol. iv. b. 8. p0int of fleetnefs is very doubtful, his make being fo entirely different from that of the Arabian ; but if beautiful fymmetry of parts, great fize and ftrength, the moft agile, nervous, and elaftic movements, great endurance of fatigue, docility of temper, and feeming attachment to men beyond that of any other domef- tic animal, can proniife any tiling for a ftallion, the Nubian is above all companion the moft eligible in the world.” He thinks, and juftly thinks, that an at¬ tempt fliould at leaft be made to import them into this kingdom. “ The expence (he fays) would not be great, though there might be fome trouble and appli¬ cation neceffary : but if adroitly managed, there would not be much even of that. I he Nubians are very jea¬ lous in keeping Up the pedigree of their horfes, which are black or white, but a vaft proportion of the former to the latter.” Our author never faw the colour which we call gray, i. e. dappled \ but he has feen fome bright bays, and fome inclined to forrel. All noble horfes in Nubia are faid to be defcended of one of the five ch. 10. upon which Mahomet and his four immediate fuccef- fors, Abu Beer, Omar, Atmen, and Ali, fled from Mec¬ ca to Medina the night of the Hegira. No one will pay much regard to this legendary tale, or believe that the ftrength and beauty of this breed of horfes is owing to any virtue communicated to the firft of them by the prophet and his apoftles. Mr Bruce accounts for their excellence upon rational principles. “ The beft horfes of the Arabian breed are found (he fays) in the tribe of Mowelli and Annecy, which is about 36° north la¬ titude. Dangola, which is in 20° latitude, feemed to him to be the centre of excellence for this noble ani¬ mal.” Hence he infers, that the bounds in which the borfe is in greateft perfection, are between the 20th and 36th degrees of latitude, and between 30 degrees of, longitude ealt from Greenwich and the banks of the. Euphrates. L to the effedts of climate we add the, manner of feeding the Nubian horfes, ,we ftiall perhaps, have the tru“ caule of their fuperiority over all others. “ They are kept fat upon dora, and fuffered to eat no¬ thing green but the fhort roots of graft that art. to be found by the fide of the Nile, after the fun has withered it. Tlus is dug out where it is covered with earth, and appears blanched, and laid in fmall heaps once a-day on the ground before them.” NUBIAN desert, a vaft trad! of barren rocks and burning fands, extending from Syene in Upper Egypt to Geon, the capital of Berber in Nubia. As Syene is in latitude 240 o' 45" north, and Geon in latitude I7° 57' 22,/? the length of this defert from north to fouth is 6° 3' 23", or upwards of 420 Englifh miles. Its breadth from eaft to weft has not, as far as we know, been precifely afeertained. Through this hor-. rid region, where nothing is to be feen which has the breath of life, muft all travellers pafs from Sennaar to Egypt ; in danger every moment of perilhing by thirft, being overwhelmed by moving columns of fand, fuffo- cated by a hot and poifonous wind, or cut in pieces by troops of wandering Arabs. The laft European of whom we have heard that made the journey and lived to give an account of it, is Mr Bruce ; and the perfon muft have neither tafte nor fenfibility who can read un¬ moved his manly narrative. No fingle traveller, nor even a caravan, can enter with fafety into this deleft, but under the protection of a Hy- bear ; whofe title and office are thus explained by Mr Bruce : “ A Hybear is a guide, from the Arabic word Hubbar, which fignifies to inform, inftruCt, or direft, becaufe they are ufed to do this office to the caravans travelling through the defert in all directions. They are men of great confideration, knowing perfectly the fituation and properties of all kinds of water to be met with on the route, the diftance of wells, whether oc¬ cupied by enemies or not j and if fo, the way to avoid them with the leaft inconvenience. It is alfo necelfary that they fliould know the places occupied by the Si¬ moom, and the feafons of its blowing (fee Simoom), as well as thofe occupied by moving fands.”—Under the conduCt of one of thefe men, Mr Bruce, with , in¬ finite fortitude and addrefs, paffed through the defert in the year 1772, furmounting dangers at which one fliud- ders in his clofet. Of thefe, the following, which we fliall give in the nervous language of the author, may ferve as an inftance. “ We were here (at a place called Weadiul Halboub') L 2 at Nubia, Nubian Defert. JJnbian Deiert * Bruce's Tranels, -rol. iv. N U C [ ^4 ] N U M at once furprifed and terrified by a fight furely one of the moft magnificent in the world. In that vaft ex- panfe of defert, from W. and to NW. of us, we faw a number of prodigious pillars of fand at different di- fiances, at times moving with great celerity, at others Halting on with a majeilic llownefs. At intervals we thought they were coming in a very few minutes to overwhelm us 5 and fmall quantities of fand did actually more than once reach us. Again they would retreat fo as to be almoil out of fight -, their tops reaching to the very clouds. There the tops often feparated from the bodies ; and thefe once disjoined, difperfed in the air, and did not appear more. Sometimes they were broken in the middle as if ftruck with a large cannon fhot. About noon they began to advance with confiderable fwiftnefs upon us, the wind being very ftrong at north, j&leven of them ranged alongfide of us about the di- jftance of three miles. The greateft diameter of the largeft appeared to me at that diitance as if it would meafure 10 feet. They retired from us with a wind at SE. leaving an impreffion upon my mind to which I can give no name j though furely one ingredient in it was fear, with a confiderable degree of wonder and sdtonifhment.” If it be true, as the author of A Philofophical In¬ quiry into the Origin of our Ideas of the Sublime and Beautiful affirms, that “ the paffion raifed by the fublime is aftoniffiment, and that aftonilhment is that ftate of the foul in which all its motions are fufpended with fome degree of horror,” furely a more fublime fpe&acle was never prefented to mortal eyes, than that which was on this occafion prefented to Mr Bruce. It mull have been awfully majeftic *, but few', w'e believe, would choofe the pleafure of contemplating fuch a feene of magnifi¬ cence at the hazard of that dreadful death with which at every moment it threatened our traveller and his at¬ tendants. He, indeed, had firmnefs of mind to Hand Hill and admire it 5 but his companions fhrieked out; while fome of them exclaimed that it w'as the day of judgment, and others that it was hell or the world fet on fire. But for a more particular account of this phe¬ nomenon, as well as of the nature of the defert and the proper way of paffing it, we mull refer to tile work from which this ffiort fketch is taken*. NUCLEUS, in general, denotes the kernel of a nut, or even any feed enclofed within a hulk. The term nucleus is alfo ufed for the body of a comet, otherwfife called its head. NUCTA, a dewr, which falling in Egypt about St John’s day, is by the fuperliitious natives of the country confidered as miraculous, and the peculiar gift of that faint. Its effefts are indeed fo beneficial, that this belief is little furprifing among a people fo totally ignorant of natural caufes as the modern Egyptians, for it is acknowdedged, by the moft enlightened travellers, to flop the plague, and announce a fpeedy and plentiful inundation of the country. Thefe effefts are thus ra¬ tionally accounted for by Mr Bruce. “ In February and March, the fun is on its ap¬ proach to the zenith of one extremity of Egypt, and of courfe has a very confiderable influence upon the other. The Nile having now fallen low, the water in certain old cifterns, which, though they ft ill exift, are fuffered to accumulate all 'he filth of the river, be¬ comes putrid, and the river itfelf has loft, all its finer 2 and volatile parts by the continued adion of a vertical * NudU fun } fo that inftead of being fubjed to evaporation, it II grows daily more and more inclined to putrefadion. . uma^ About St John’s day it receives a plentiful mixture of the freffi and fallen rain from Ethiopia, which di¬ lutes and refreffies the almoft corrupted river, and the fun near at hand exerts its influence upon the water, which is now become light enough to be exhaled, though it has ftill with it a mixture of the corrupted fluid. It is in February, March, or April only, that the plague begins in Egypt.” Our philofopbical traveller does not believe it an endemical difeafe ; but affigns very fuffi- cient reafons for thinking that it comes from Conftan- tinople with merchandife or with paffengers at the very time of the year when the air, by the long abfence of dews, has attained a degree of putridity proper to re¬ ceive it. In this ftate of the atmofphere, the infec¬ tion continues to rage till the period of St John’s day* when it is fuddenly flopped by the dews oceafioned by a refreffiing mixture of rain -water, which is poured into the Nile at the beginning of the inundation. The firft and moft remarkable fign of the change effeft- ed in the air, is the hidden Hopping of the plague. Every perfon, though ffiut up from fociety for months before, buys, fells, and communicates with his neigh¬ bour without any fort of apprehenfion ; and as far as our author could learn upon fair inquiry, it was never known that one fell fick of the plague after the anni- verfary of St John. He admits that fome have died of it after that period ; but of them the difeafe had got fuch hold, under the moft putrid influence of the air, that they could not recover. To corroborate this theory, which attributes fo much to the benign influ¬ ence of the falling dew, he obferves, that immediately after St John’s day, the clothes of the many thoufands who have died during the late continuance of the plague are publicly expofed in the market place j and that all thele, though confifting of furs, cotton, filk, and woollen cloths, which are the fluffs moft retentive of infedtion,. imbibing the moift air of the evening and the morning, are handled, bought, put on and worn, without any ap- prehonfion of danger, and without a Angle accident be¬ ing known to have happened to any one poflefied of this happy confidence. NUDITIES, in painting and Sculpture, tbofe parts of -a-human figure which are not covered with any drapery •, or thofe parts where the carnation appears. NULLITY, in Zaxu, fignifies any thing that is null or void : thus there is a nullity of marii ige, where per- fons marry within the degrees, or where infants marry without eonfent of iheir parents or guardians. NUMA Pompilius, the fourth fon of Pompilius Pompo, an illuftrious Sabine. He had married Tatia, the daughter of King Tatius, and together with her remained in his native country, preferring the tran¬ quillity of a private life to the fplendour of a court. Upon the death of his wife, with whom he had lived thirteen years, he gave himfelf up entirely to the ftudy of wifdom; and, leaving the city of Cures, confined himfelf to the country, wandering from fblitude to folitude, in fearch only of thofe -woods and fountains which religion Had made facred. His reclufe life gave' rife to the fable, wh-ch w'as very early received among the Sabines, that Numa lived in familiarity with the nymph'Egeria. Upon the death of Romulus, both the- fenata N U M r 85 ] N U M Noma, fenate and people ftrongly folicited him to be their king. —y—i They defpatched Julius Proculus and Valerius Volefus, two fenators of diftinftion, to acquaint Numa with their refolution, and make him an offer of the king¬ dom. The Sabine philofopher rejefted at firft their propofal j but being at lait prevailed upon by the ar¬ guments and entreaties of the deputies, joined with thofe of his father and of Martius his near relation, he yielded ; and having offered facrifices to the gods, fet out for Rome, where he was received by all ranks of people with loud fhoutsof joy. Spurius Vettius, the interrex for the day, having affembled the curiae, he ^vas ele&ed in due form, and the eleftion was unanimoufly confirmed by the fenate. The beginning of his reign was popular ; and he difmiffed the 300 bodyguards which his predeceffor had kept around his perfon, and obferved, that he did not diltruft a people who had compelled him to reign over them. He was not, like Romulus, fond of war and military expeditions, but he applied himfelf to tame the ferocity of his fubje&s, to inculcate in their minds a reverence for the Deity, and to quell their diflenfions by dividing all the citizens into different clafles. He efta- blifhed different orders of priefts, and taught the Ro¬ mans not to worfhip the Deity by images $ and from his example no graven or painted ftatues appeared in the temples or fan&uaries of Rome for the fpace of 160 years. He encouraged the report that was fpread of his paying regular vifits to the nymph Egeria, and made ufe of her name to give fandlion to the laws and inftitutions which he had introduced. He eftablifhed the college of the veftals, and told the Ramans that the fafety of the empire depended upon the prefervation of the facred anajle or fhield, which, as was generally believed, had dropped from heaven. He dedicated a temple to Janus, which, during his whole reign, remain¬ ed (hut as a mark of peace and tranquillity at Rome. After a reign of 42 years, in which lie had given every oflible encouragement to the ufeful arts, and in which e had cultivated peace, Numa died in the year of Rome 82. Not only the Romans, but alfo the neigh¬ bouring nations, were eager to pay their laft offices to a monarch whom they revered for his abilities, mode¬ ration, and humanity. He forbade his body to be burnt according to the cuftom of the Romans j but he ordered it to be buried near Mount Janiculum, with many of the books which he had written. Thefe books were accidentally found by one of the Romans, about 400 years after his death ; and as they contained nothing new or interefting, but merely the reafons why he had made innovations in the form of worfhip and in the re¬ ligion of the Romans, they were burnt by order of the fenate. He left behind him one daughter called Pom- pilia, who married Numa Marcius, and became the mo¬ ther of Ancus Marcius the fourth king of Rome. Some fay that he had alfo four fons •, but this opinion is ill founded. The principal laivs of King Numa, men¬ tioned by different authors, are, I. That the gods fhould be worfhipped with corn and a falted cake. 2. That whoever knowingly killed a free man, fhould be held, as a parricide. 3. That no harlot fhould touch the altar of Juno j and if (he did, that (he fhould facrifice a ewe-lamb to that goddefs, with diffievelled hair. 4..That whoever removed a land-mark fhould be put to death. 5. That wine fhould not be poured on a funeral Num* pile, &c. II NUMANTIA, a very noble city, the ornament of, "v,u™1)er- the Hither Spain, (Florus) j celebrated for the long war of 20 years which it maintained againfl the Ro¬ mans. The bafenefs and injuftice of the Romans during this war were truly difgraceful to them, and altogether unworthy of a great and powerful people. The inha¬ bitants obtained fome advantages over the Roman forces, till Scipio Africanus was empowered to finifh the war and to fee the deftrudtion of Numantia. He began the fiege, with an army of 60,000 men, and was bravely oppofed by the befieged, who were no more than 4000 men able to bear arms. Both armies be¬ haved with uncommon valour, and the courage of the Numantines was foon changed into defpair and fury. Their provifions began to fail, and they fed upon the flefh of their horfes, and afterwards on that of their dead companions, and at laft they were obliged to draw lots to kill and devour one another. The melancholy fituation of their affairs obliged them to furrender to the Roman general. Scipio demanded them to deliver themfelves up on the morrow ; they refufed, and when a longer time had been granted to their petitions, they retired and fet fire to their houfes and deftroyed them¬ felves, fo that not even one remained to adorn the tri¬ umph of the conqueror. Some hiftorians, howeVer, deny that; and affert, that a number of Numantines delivered themfelves into Scipio’s hands, and that 50 of them were drawn in triumph at Rome, and the reft fold as Haves. The fall of Numantia wras more glorious than that of Carthage or Corinth, though the place was much inferior to them. It was taken by the Ro¬ mans, A. U. C. 629 ; and the conqueror obtained the furname of Numanticus. NUMBER, an affemblage of feveral units, or things of the fame kind. See Arithmetic, and Metaphy¬ sics, N° 205—208. Number, fays Malcolm, is either abftraift or appli¬ cate : Abftradft, when referred to things in general, without attending to their particular properties ; and applicate, when confidered as the number of a particu¬ lar fort of things, as yards, trees, or the like. When particular things are mentioned, there is al¬ ways fomething more confidered than barely their numbers $ fo that what is true of numbers in the ab- ftradl, or when nothing but the number of things is confidered, will not be true when the queftion is li¬ mited to particular things : for inftance, the number two is lefs than three ; yet two yards is a greater quantity than three inches : and the reafon is, becaufe regard muft be had to their different natures as well as number, whenever things of a different fpecies are confidered ; for though we can compare the number of fuch things abftraftedly, yet we cannot compare them in any applicate fenfe. And this difference is ne- ceffary to be confidered, becaufe upon it the true fenfe, and the poffibility or impoflibility, of fome queftions 1 depend. Number is unlimited in refpeft of increafe; becaufe we can never conceive a number fo great but ftill there is a greater. However, in refpeft of decreafe, it is li¬ mited •, unity being the firft and leaft number, below which therefore it cannot defeend. Kinds N U M [ 86 ] N U M ''fumber. Kinds anddijhndhonsofNuMBEBS. Mathematicians, 1 . confidering number under a great many relations, have , eftablifhed the following diftinaions. Broken numbers are the fame with fraaions. Cardinal numbers are thofe which exprefs the quan¬ tity of units, as i, 2, 3, 4, &c. whereas ordinal num¬ bers are thofe which exprefs order, as ift, 2d, 3d, &c. Compound number, one divilible by fome other num¬ ber befides unity ; as 12, which is divifible by 2, 3, 4, and 6. Numbers, as 12 and 15, which have lome com- mofi meafure belides unity, are faid to be compound numbers among themfelves. Cubic number is the produa of a fquare number by its root: fuch is 27, as being the produa of the fquare number 9 by its root 3. All cubic numbers, whofe root is lefs than 6, being divided by 6, the re¬ mainder is the root itfelf} thus 27 —-6 leaves the re¬ mainder 3, its root $ 215,_ the cube of 6, being di¬ vided by 6, leaves no remainder •, 343* ^ie. cuJDe 0 leaves a remainder 1, which added, to 6, is the cube root; and 512, the cube of 8, divided by 6, leaves a remainder 73 which added to 6,. is the cube root. Hence the remainders of the divifions of the cubes above 216, divided by 6, being added to 6, always give the root of the cube fo divided till that remainder be 5, and confequently 11, the cube root of the.number divided. But the cubic numbers above this being divided by 6, there remains nothing, the cube root be¬ ing 12. Thus the remainders of the higher cubes are to be added to 12 and not to .6, till you come to 18, when the remainder of the divilion mull be added to 18 j and fo on ad vifimtwn. Determinate number is that referred to fome given unite, as a ternary or three : whereas an indeterminate one is that referred to unity in general, and is called Homogeneal numbers are thofe referred to the fame unit ; as thofe referred to different units are termed heterogeneal. Whole numbers are otherwife called integers. Rational number is one commenfurable with unity ; as a number, incommenfurable with unity, is termed irrational, or a furd. . . , In the fame manner, a rational whole number is that whereof unity is an aliquot part; a rational broken number, that equal to fome aliquot part of unity ; and a rational mixed number, that confiding of a whole num¬ ber and a broken one. # Even number, that which may be divided into two equal parts without any fraclion, as 6, 12, &c* 1 “e fum, difference, and produft, of any number of even numbers, is alway an even number. An evenly even number, is that which may be mea- fured, or divided, without any remainder, by another even number, as 4 by 2. ■ An unevenly even number, when a number may be equally divided by an uneven numbei, as 20 by 5. " Uneven number, that which exceeds an even number, at lead; by unity, or which cannot be divided into two equal parts, as 3, 5, &c. The fum or difference of two uneven numbers makes an even number 5 but the faaum of two uneven ones makes an uneven number. If an even number be added to an uneven one : or it the one be fubtrafted from the other, in the former 3 cafe the fum, in the latter the difference, is an uneven Number, number ■, but the fadtum of an even and uneven num- v~~— ber is even. The fum of any even number of uneven numbers is an even number; and the fum of any uneven number of uneven numbers is an uneven number. Primitive or prime numbers are thofe divifible only by unity, as 5, 7, &c. And prime numbers among themielves, are thofe which have no common meafure befides unity, as 12 and 19. Perfeft number, that whofe aliquot parts added to¬ gether make the whole number, as 6, 28 5 the aliquot parts of 6 being 3, 2, and 1, —6 5 and thofe of 28, be¬ ing 14, 7, 4, 2, 1, =28. Imperfedt numbers, thofe whofe aliquot parts added together make either more or lefs than the whole. And thefe are diftinguilhed into abundant and defec¬ tive : an inftance in the former cafe is 12, whofe ali¬ quot parts 6, 4, 3, 2, I, make 16 *, and in the latter cafe 16, whole aliquot parts 8, 4, 2, and 1, make but 15. ... Plane number, that arifing from the multiplication of two numbers, as 6, which is the produdl of 3 by 2 j and thefe numbers are. called thejides of the plane. Square number is the produa of afiy number multi¬ plied by itfelf; thus 4, which is the fadum of 2 by 2, is a fquare number. Even fquare number added to its root makes an even number. Figurate numbers, are fuch as reprefent lome geo¬ metrical figure, in relation to ubich they aie always confidered } as triangular, pentagonal, pyramidal, S^c. numbers. Figurate numbers are diflinguilhed into orders, ac¬ cording to their place in the fcale of their generation, being all produced one from another, viz. by adding continually the terms of any one, thc.fucceffive lums are the terms of the next order, beginning from the firit order which is that of equal units I, 1, I, I, &c. ; then the 2d order confitts of the fucceffive fums of thofe of the iff order, forming the arithmetical progreffion 1, 2, 3, 4, &c. j thofe of the third order are the fucceffive fums of thofe of the 2d, and are the triangular num¬ bers 1, 3, 6, xo, 15, &c. ; thofe of the fourth order are the fucceflive fums of thofe of the 3d, and are the py¬ ramidal numbers I, 4, 10, 20, 35, &c. j and fo on as below : Order. 1, 2 v 3 4 5 6 7 Humes. Equals, Arithmeticals, Triangulars, Pyramidals, 2d Pyramidals, 3d Pyramidals, 4th Pyramidals, 1, 2, 3> 4> 5* 6, 7> Numbers. U U 4> xo, 20, 35> 56> 3> 6, 10, 21, 28, 5> 35? 7°? 126, 210, &c. &c. &c. &c. &c. &c. &c. The above are all confidered as different forts of tri¬ angular numbers, being formed from an arithmetical pro- oreffion whofe common difference is 1. But if that common difference be 2, the fucceflive fums will be the feries of fquare numbers : if it be 3,. the feries will be pentagonal numbers, or pentagons ; if it be 4, the feries will be hexagonal numbers, or hexagons and fo on. Thus: , ., . , Arithmeticals. N U M [ Number. Arithmcticals. I5 2, 3, 4> I> 3> 5> 4> 7? I0> i, 9> JS* &c. i ft Sums, or Polygons. Tri. I, 3, 6, 10 Sqrs. I, 4, 9, 16 Pent. I, 5, 12, 22 Hex. i, 6, 15, 28 2cl or 2d Polygons. 1, 4, 10, 20 1, 5> r4» 3° 1, 6, 18, .40 1, 7> 22» 5° And the reafon of the names triangles, fquares, pen¬ tagons, hexagons, &c. is, that thofe numbers may be placed in the form of thefe regular figures or polygons. But the figurate numbers of any order may alfo be found without computing thofe of the preceding orders ; which is done by taking the fuccefixve products of as many of the terms of the arithmeticals, 1, 2, 3, 4, 5, &c. in their natural order, as there are units in the num¬ ber which denominates the order of figurates required, and dividing thofe products always by the firft produff : thus, the triangular numbers are found by dividing the produffs 1X2, 2X3, 3X4, 4X5, &c. each by the ift pr. 1 X 2 j the firft pyramids by dividing the pro- duffs 1 X 2 X 3> 2 X 3 X 4? 3 X 4 X 5» &c- by the firft 1X2X3- And, in general, the figurate numbers of any order n, are found by fubftituting fucceftively I, 2, 3, 4, 5, &c. inftead of x in this general ex- „ . tf-f-i . .r4-2 . ff-l-3 . &c. preffion 5 ! J ’ 3-4 where the faftors 2 . 3 . 4 . . &c in the numerator and denominator are fuppofed to be multiplied together, and to be continued till the num¬ ber in each be lefs by 1 than that which exprefles the order of the figurates required. See Maclaurin’s Flux¬ ions, art. 351, in the notes j alfo Simpfon’s Algebra, p. 213 ; or Malcolm’s Arithmetic, p. 396, where the fubjeft of figurates is treated in a very extenfive and perfpicuous manner. Hutton's Mathematical Dill ion ary. Polygonal or polygonous numbers, the fums of arith¬ metical progreftions beginning with unity : thefe, where the common difference is 1, are called triangular nu?n- hers; where 2, fquare numbers ; where 3, pentagonal numbers ; where 4, hexagonal numbers ; where 5, hepta- gonal numbers, &c. Pyramidal numbers, the fums of polygonous numbers, colleffed after the fame manner as the polygons them- felves, and not gathered out of arithmetical progreffions, are calledyfr^ pyramidal numbers ; the fums of the firft pyramidals are called fecondpyramidals, &c. If they arife out of triangular numbers, they are called triangular pyramidal numbers ; if out of pentagons,/^? pentagonal pyramidals. From the manner of fumming up polygonal numbers, it is eafy to conceive how the prime pyramidal numbers r , . (tf—2)«34-3 ift—(a—z\n aie found, viz. ^ —— expreffes all the prime pyramidals. The number nine has a very curious property, its pro¬ duffs always compofmg either 9 or fome leffer produff of it. We have already given an account of this, with the examples from Hume, under the article Nine 5 and we need not repeat them. Did our limits permit us, we could inftance in a variety of other properties numbers both curious and furprifing. Such fpecula- tions are indeed by fome men confidered as trifling Numbers. 87 ] N U M and ufelefs : but perhaps they judge too haftily j for Number few employments are more innocent, none more inge¬ nious, nor, to thofe who have a tafte for them, more amufing. Numbers were by the Jews, as well as the ancient Greeks and Romans, expreffed by letters of the alpha¬ bet : hence wre may conceive how imperfeft and limit¬ ed their arithmetic was, becaufe the letters could not be arranged in a feries, or in different lines, conveniently enough for the purpofes of ready calculation. The in¬ vention of the cypher, or arithmetical figures, w’hich we now make ufe of, has given us a very great advantage over the ancients in this refpeff. Mankind, we may reafonably fuppofe, firft reckoned by their fingers, which they might indeed do in a va¬ riety of ways. From this digital arithmetic, very pro¬ bably, is owing the number 10, which conftitutes the whole fet of arithmetical figures. The letters chiefly employed by the Romans to ex- prefs numbers were, M, for 1000 ; D, for 500 •, C, for 100 ; L, for 50 ; V, for five 5 X, for 10 5 and I, for one..—M, probably fignified 1000, becaufe it is the initial of ?nille; D ftands for 500, becaufe it is dimi- dium mille; C fignifies 100, as being the firft letter of the word centum ; L ftands for 50, becaufe it is the half of C, having formerly been wrote thus c. ; V fig¬ nifies 5, becaufe V is the fifth vowel; X ftands for 10, becaufe it contains twice or V in a double form j I ftands for one, becaufe it is the firft letter of initium. Thefe however are fanciful derivations. See Numeral. Letters. The Jewitli cabbalifts, the Grecian conjurors, and the Roman augurs, had a great veneration for particular numbers, and the refult of particular combinations of them. Thus three, four, fix, feven, nine, ten, are full of divine myfteries, and of great efficacy. Golden Number. See Chronology, N° 27. Numbers, in Poetry, Oratory, &c. are certain mea- fures, proportions, or cadences, which render a verfe, pe¬ riod, or fong, agreeable to the ear. Poetical numbers confift in a certain harmony in the order, quantities, &c. of the feet and fyllables, which- make the piece mufical to the ear, and fit for finging, for which all the verfes of the ancients were intended.. See Poetry.—It is of thefe numbers Virgil fpeaks in his ninth Eclogue, when he makes Lycidas fay, Nu- meros mcmini, Ji verba tenerem; meaning, that al¬ though he had forgot the words of the verfes, yet he remembered the feet and meafure of which they were compofed. Rhetorical or profaic numbers are a fort of Ample un¬ affected harmony, lefs glaring than that of verfe, but fuch as is perceived and affefts the mind with pleafure.' The numbers are that by which the ftyle is faid to be eafy, free, round, flowing, &c. Numbers are things abfolutely neceffary in all writing, and even in all fpeech- Hence Ariilotle, Tully, Quintilian, &c. lay down abun¬ dance of rules as to the beft manner of intermixing dac- tyles, fpondees, anapefts, &c. in order to have the num¬ bers perfect. The fubftance of what they have faid, is reducible to what follows : 1. The ftyle becomes nu¬ merous by the alternate difpofition and temperature of. long and ffiort fyllables, fo as that the multitude of ffiort ones neither render it too hafty, nor that of long one& too.- N U M r 88 ] N U M Number?, too flow and languid : fometimes, indeed, long and Numeral.^ fyi]abtes are thrown together defignedly without ^ any fuch mixture,, to paint tlie flownefs or celerity of any thing by that of the numbers j as in thefe verfes of Virgil: Uli inter fefe magna vi brachia toliunt; and Rad it iter Jiquidum, celeres neque cornmomet alas. 2. The flvle becomes numerous, by the intermixing words of one, two, or more fyllables j whereas the too frequent repetition of monofyllables renders the ftyle pitiful and grating. 3. It contributes greatly to the numeroufnefs of a period, to have it cl oft d by magnifi¬ cent and well-founding words. 4. The numbers depend not only on the noblenefs of the words in the clofe, but * of thofe in the whole tenor of the period. 5. To have the period flow eafily and equally, the harfli concur¬ rence of letters and words is to be ftudioufly avoided, particularly the frequent meeting of rough confonants ; the beginning the fir ft fy liable of a word with the laft of the preceding *, the frequent repetition of the fame letter or fyllable •, and the frequent ufe of the like end¬ ing rvords. Laftly, The utmoft care is to be taken, left, in aiming at oratorial numbers, you fhould fall into poe- . tical ones 5 and inftead of profe, write verfe. Book of Numbers, the fourth book of the Penta¬ teuch, taking its denomination from its numbering the families of Ifrael. A greater part of this book is hiftorical, relating to fe- veral remarkable paffages in the Ifraelites march through the wildernefs. It contains a diftinft relation of their feveral movements from one place to another, or their 42 ftages through the wildernefs, and many other things, ■ whereby we are inftrutfted and confirmed in fome of the weightieft truths that have immediate reference to God and his providence in the world.-—But the greateft part of this book is fpent in enumerating thofe laws and ordinances, whether civil or ceremonial, which Were given by God, but not mentioned before in the preced¬ ing books. NUMERAL letters, thofe letters of the alphabet which are generally ufed for figures ; as I, one ; V, five ; X, ten ; L, fifty ; C, a hundred j D, five hundred j M, a thoufand, &c. It is not agreed how the Roman numerals originally received their value. It has been fuppofed, as we have obferved in the end of the article Number,. that the Romans ufed M to denote 1000, becaufe it is the firft letter of mille, which is Latin for 1000; and C to de¬ note 100, becaufe it is the firft letter of centum, which is Latin for 100. It has alfo been fuppofed, that D, being formed by dividing the old M in the middle, was therefore appointed to ftand for JOO, that is, half as much as the M flood for when it was whole ; and that L being half a C, was, for the fame reafon, ufed to de¬ nominate 50. But what reafon is there to fuppofe, that 1000 and 100 zvere the numbers which letters were firft ufed to exprefs ? And Avhat reafon can be afligned why D, the firft letter in the Latin Avord decern, ten, ftiould not rather have been chofen to ftand for that number, than for 500, becaufe it had a rude refemblance to half an M ?—But if thefe queftions could be fatisfaftorily anfAvered, there are other numeral letters which have never yet been accounted for at all. Thefe confidera- tions render it probable that the Romans, did not, in Numeral, their original intention, ufe letters to exprefs numbers at all ; the moft natural account of the matter feems to be this : The Romans probably put down a fingle ftroke, I, fur one, as is ftill the practice of thofe Avho fcore on a flate or Avith chalk : this ftroke, I, they doubled, trebled, and quadrupled, to exprefs 2, 3, and 4 : thus, II. ill. IIII. So far they could eafily number the ftrokes Avith a glance of the eye. But they prefently found, that if more Avere added, it Avould foon be neceflary to tell the ftrokes one by one : for this reafon, then, when they came to 5, they expreffed it by joining tAvo ftrokes to¬ gether in an acute angle thus, V j which Avill ap¬ pear the more’probable, iT it be confidered that the progreflion of the Roman numbers is from 5 to 5, i. e. from the fingers on one hand to the fingers on the other.—Ovid has touched upon the original of this in his Faforum, lib. iii. and Vitruvius has made the fame remark. After they had made this acute angle V. for five, they added the fingle ftrokes to it to the number of 4, thus, VI. VII. VIII. VIIII. and then as the ftrokes could not be further multiplied Avithout confufion, they doubled their acute angle by prolonging the two lines beyond their interfeftion thus, X, to denote tAvo fives, or ten. After this they doubled, trebled, and quadru¬ pled, this double acute angle thus, XX. XXX. XXXX. they then, for the fame reafon which induced them firft; to make a fingle and then to double it, joined two tingle ' ftrokes in another form, and inftead of an acute angle, made a right angle L, to denote fifty. When this 50 was doubled, they then doubled the right angle thus E, to denote zoo, and having numbered this double right angle four times, thus EE EEE EEEE j when they came to the fifth number, as before, they reverted it, and put a fingle ftroke before it thus it, to denote 500 ; and when this 500 Avas doubled, then they alfo doubled their double right angle, fetting two double right angles op- polite to each other, Avith a fingle ftroke between them, thus EI3 to denote 1000 : Avhen this note for 1000 had been four times repeated, then they put doAvn 133 for 5000, EEI33 for 10,000, and 1333 for 50,000, and EEEl333for 100,000,13333 forjOO,OOO and EEEEI3333 for one million. That the Romans did not originally write M for 1000, and C for ZOO, but fquare charafters, as they are written above, we are exprefsly informed by Paulus Manutius} but the corners of the angles being cut off by the tranfcribers for defpatch, thefe figures Avere gra¬ dually brought into Avhat are noAV numeral letters.— When the corners of E13 were made round, it flood thus cid, Avhich is fo near the Gothic on, that it foon deviated into that letter ; fo 13 having the corner made round, it flood thus 13, and then eafily deviated into D. L alfo became a plain C by the fame means \ the fingle re&angle Avhich denoted 50, was, without alteration, a capital L the double acute angle Avas an X ; the fingle acute angle a V confonant; and a plain fingle ftroke, the letter I; and thus thefe feven letters, M, D, C, L, X, V, I, became numerals. Numeral CharaBers of the Arabs, are thofe figures which are norv ufed in all the operations of arithmetic in every nation in Europe. We have elfeAvhere ftiown that the Arabs derived the ufe of them moft probably from ' • N U M Numeral from India, (See Arithmetic, N° 5.). H . however, though very generally received, has been con- Numencal. troverte(i with fome ingenuity. A writer in the Gentle¬ man’s Magazine, at a period when that mifcellany was in its higheft reputation, thus endeavours to prove that the Arabs derived their notations from the Greeks. “ I maintain (fays he) that the Indians received their nu¬ meral chara£ters from the Arabians, and the Arabians from the Greeks, as from them they derived all their learning, which in fome things they improved, but for the moft part have altered. The numerical figures which they received from the Greeks are proofs of this altera¬ tion 5 which is fo great, that without particular atten¬ tion one can fcarce difeover in t hem the veftiges of their origin. But when we compare them carefully and with¬ out prejudice, we find in them manifeft traces of the Greek figures. The Greek numerical figures were no other than the letters of their alphabet. A fmall Broke was the mark of unity. The B, being abridged of its two extremities, produced the 2. If you incline the y a little on its left fide, and cut off its foot, and make the left horn round towards the left fide, you will produce a 3 ; the A makes the 4, by railing the right leg perpen¬ dicularly, and lengthening it a little below the bale, and lengthening the bafe on the left fide. The s forms the 5, by turning the loweft femicircle towards the right, which before was turned towards the left fide. I he number 5 forms the 6 by having is head taken off, and its body rounded. Z, by taking away the bale, makes the 7. If we make the top and bottom-of H round, we lhall form an 8. The 9 is the 9 with very little al¬ teration. The cypher o was only a point, to which one of the figures was added to make it Hand for ten times as much. It was neceffary to mark this point very ftrong- ly •, and in order to form it better, a circle was made, which was filled up in the middle; but that cireum- ftancc was afterwards negle&ed. Theophanes, an hifte- rian of Conllantinople, who lived in the ninth century, fays exprefsly, that the Arabians retained the Greek fi¬ gures, having no characters in their language to repre- fent all the numbers. The Greeks obferved in thtjir numbers the decuple progreffion, which the Arabians have retained. Certain characters are found in the Greek alphabet, which are not ufed in reading, but on¬ ly in calculation, and for this reafon they are iiyled Epifemes, that is to fay, notes, marks, in order to diftin- guilh them from letters. The number 6 derives its form from one of thefe epifemes, which was called tmo-mpcv fiav. This epifeme forms the letter F among the ZEohansand among the Latins. This was called the Digamma, lb llyled from its figure, which feems to have been one r placed upon another. That this reafoning is plaufible will hardly be que- fiioned ; but whether it be conclufive our readers mull; determine. It has not convinced ourfelves ; but through the whole of this work we with to Hate candidly the dif¬ ferent opinions held on every fubjeCl of curiofity and ufefu'nefi. NUMERATION, or Notation, in Arithmetic, the art of expretfing in characters any number propofed in words, or of exprefling in words any number propofed in characters. See Arithmetic, N° 7. NUMERICAL, Numerous, or Numeral, fomething belonging to numbers j as numerical algebra is that which makes ufe of numbers, inltead of letters of the Vol. XV. Part I. If . Nutnuiia. [ 89 ] N U M This opinion, alphabet.— Alfo numerical difference is that by which Numerical one man is diftinguifhed from another. Hence a thing is faid to be numerically the fame, when it is fo in the ftriCtcft fenfe of the word. NUMIDA, a genus of birds belonging to the order of gallinse. See Ornithology Index. NUMIDIA, an ancient kingdom of Africa, bound¬ ed on the north by the Mediterranean fea; on the fouth by Gsetulia, or part of Libya Interior j on the weft by the Mulucha, a river which feparated it from Maurita¬ nia ; and on the eaft by the Tufca, another river which - bounded it in common with Africa Propria. Dr Shaw lias rendered it probable, that the river which formerly went under the denominations of Malva, Malvana, Mu- lucha, and Molochath, is the fame with that now called Mullooiah by the Algerines-, in which cafe, the king¬ dom of Numidia muft have extended upwards of 500 miles in length: its breadth, however, cannot be fo well afeertainedj but fuppofing it to have been the fame with that of the prefent kingdom of Algiers, in the narrow- eft part it muft have been at leait 40 miles broad, and in the widell upwards of 100. ‘ t This-country included two diftriCls ; one inhabited Anaent di- by the Majfj/li, and the other by the Mu/jaf/ii; the lat- ter being alio called in after times, Mauritania Cm far i- enjis, and the former Numidia Propria. The country of the Maffyli, or, as fome call it, Terra Metagonitis, was feparated from the proper territory of Carthage by its eaftern boundary the river Tufca, and from the king¬ dom of the Mafllefyli, or Mauritania Ctefarienfis, by the river Ampfaga. It feems to conefpond with that part of the province of Conftantina lying between the Zaine and the Wed al Kibeer, which is above 130 miles long, and more ’^an 100 broad. The fea coaft of this pro¬ vince is for the moft part mountainous and rocky, an- fwering to the appellation given to it by Abulfeda, viz. El Edwaa, the high or lofty. It is far from being equal in extent to the aqcient country of the Maffsefyli, which, Strabo informs us, was yet inferior to the country of the Maffyli. Its capital was Cirta, a place of very .confi- derable note among the ancients. „ The moft celebrated antiquarians agree, that the tra'Ci, Peopled by extending from the ifthmus of Suez to the lake Trito-tlie nis, was chiefly peopled by the defeendants of Miz-pj^^ar!rs raim, and that the pofterity of his brother Put, or Phut, fpread themfelves all over the country between that lake and the Atlantic ocean. To this notion He¬ rodotus gives great countenance: for he tells us, that the Libyan Nomades, whofe territories to the well were bounded by the Triton, agreed in their cuftoms and manners with the Egyptians 5 but that the Afri¬ cans, from that river to the Atlantic ocean, differed in almoft all points from them. Ptolemy mentions a city called Putea near Adrametum •, and Pliny, a river of Mauritania Tingitana, known by the name of Fut, or Phut ; and the diftrifil adjacent to this river was cal¬ led Rcgio Phutenfis, which plainly alludes to the name of Phut. That word fignifies fcattered, or difperfed, which very well agrees with what Mela and Strabo re¬ late of the ancient Numidians ; fo that we may, without any fcruple, admit the aborigines of this country to have been the delcendants of Phut. The hiftory of Numidia, during many of the early Grcrt pnrt ages, is buried in oblivion. It is probable, however, of the hi- that as the Phoenicians were mailers of a crcat part of !i0ry un~ -fi/r ° 1 .1 known. M the N U M [’ 90 ] N U' M N’umidiaf Hiftory of Syphax and MafiniiTa. the country, thefe'tranfadions had been recorded, and generally known to the Carthaginians, King Jarbas probably reigned here as well as in Africa Propria, if not in Mauritania, and other parts of Libya, when Di¬ do began to build Byrfa. It appears from Juftin, that about the age of Herodotus, the people of this country were called both Africans or Libt/ans and Numidiuns. Jurtin likewife intimates, that about this time the Car¬ thaginians vanquilhed both the Moors or Mauritanians and the Numidians •, in confequence of which they were excufed from paying the tribute which had hitherto been demanded of them. After the conclufion of the firft Punic war, the Afri¬ can troops carried on a bloody conteft againft their ma¬ ilers the Carthaginians *, and the moft active in this re¬ bellion, according to Diodorus Siculus, -were a part of the Numidian nation named Micatamans. This fo in- cenfed the Carthaginians, that after Hamilcar had either killed or taken prifoners all the mercenaries, he font a large detachment to ravage the country of thole Numi¬ dians. The commandant of that detachment executed his orders with the utmolf cruelty, plundering the di- ftrift in a terrible manner, and crucifying all the prifo¬ ners without diilinffion that fell into his hands. This filled the reft with fuch indignation and refentment, that both thev and their pofterity ever afterwards bore an implacable hatred to the Carthaginians. In the time of the fecond Punic -war, Syphax king of the Mafthefyli entered into an alliance with the Ro¬ mans, and gave the Carthaginians a confiderable defeat. This induced Gala, king of the Maffyli, to conclude a treaty with the Carthaginians, in confequence of which his fon Maliniffa marched at the head of a powerful army to give Syphax battle. The conteft ended in fa¬ vour of Mafmiffa \ 30,000 of the MaiTaefyli were put to the fword, and Syphax driven into Mauritania 5 and the like bad fuccefs attended Syphax in another engagement, where his troops w'ere entirely defeated and difperfed. Gala dying whilft his fon Mafiniffa was afting at the head of the Numidian troops fent to the afliftance of the Carthaginians in Spain, his brother Defalces, according to the eftablilhed rules of fucceflion in Numidia, took pofleffion of the Maffylian throne. That prince dying foon after his fucceflion, Capufa. his eldeft fon fucceeded. him. But he did not long enjoy his high dignity •, for one Mezetulus, a perfon of the royal blood, but an ene¬ my to the family of Gala, found means to excite a grea-t part of his fubjefts to revolt. A battle foon took place between him and Capufa •, in which the latte* was flain with many of the nobility, and his army entirely de¬ feated. But though Mezetulus thus became poffefled of the fovereignty, lie did not think -proper to aflume the title of king, but ftyled himfelf guardian to Lacu- maces, the furviving fon of Defalces, whom he graced with the royal title. To fupport himfelf in his ufurpa- tion, he married the dowager of Defalces, who was Hannibal’s niece, and confequently of the moft power¬ ful family in Carthage. In order to attain the fame end, he fent ambaffadors to Syphax, to conclude a treaty of alliance with him. In the mean time Mafinifla, re¬ ceiving advice of his uncle’s death, of his coufin’s {laugh¬ ter, and of Mezetulus’s ufurpation, immediately pafled over to Africa, and went to the court of Bocchar king of Mauritania to folicit fuccours. Bocchar, fenfible of the great injuftice done Mafiniffa, gave him a body of 4000 Moors to efeort him to his dominions. His fub- jedts, having been apprifed of his approach, joined him Nemidia. upon the frontiers with a party of 500 men. The v— Moors, in purfuance of their orders, returned home, as foon as Maiiniffa reached the confines of his kingdom. Notwithhanding which, and the fmall body that decla¬ red for him having accidentally met Lacumaces at Thapfus with an efcort going to implore Syphax’s alhit- ance, he drove him into the town, which he carried by affault after a faint refiftance. However, Lacumaces,. with many of his men, found means to efcape to Sy¬ phax. The fame of this exploit gained Maiiniffa great credit, infomuch that the Numidians flocked to him from all parts, and amongft the reft, many of his father Gala’s veterans, -who prelfed him to make a fpeedy and vigorous pufh for his hereditary dominions. Lacuma¬ ces having joined Mezetulus with a reinforcement of Maffaefylians, which he had prevailed upon Syphax to fend to the afliftance of his ally, the ufurper advanced at the head of a numerous army to offer Mafiniffa bat¬ tle *, which that prince, though much inferior in num¬ bers, did not decline. Hereupon an engagement en~ fued } -which notwithftanding the inequality of numbers ended in the defeat of Lacumaces. The immediate confequence of this vidlory of Mafiniffa was a quiet and peaceable poffeflion of his kingdom 5 Mezetulus and Lacumaces, with a few that attended them, flying into the territories of Carthage. However, being apprehen- five that he fliould be obliged to fuftain a war againft: Syphax, he offered to treat Lacumaces with as many marks of diftinftion as his father Gala had Defalces, provided that prince would put himfelf under his pro- tedlion. He alfo promifed Mezetulus pardon, and a re- ftitution of all the effefts forfeited by his treafonable conduff, if he would make his lubmiflion to him. Both of them readily complied with the propofal, and imme¬ diately returned home ; fo that the tranquillity and re- pofe of Numidia would have been fettled upon a folid and lafting foundation, had not this been prevented by Afdrubal, who was then at Syphax’s court. He infi- nuated to that prince, who was difpofed to live amica¬ bly with his neighbours, “ That he was greatly mifta- ken, if he imagined Mafiniffa would be fatisfied with hie hereditary dominions. That he was a prince of much greater capacity and ambition, than either his father Gala, his uncle Defalces, or any of his family. That he had difeovered in Spain marks of a moft rare and uncommon merit. And that, in fine, unlefs his rifing flame was extinguiftied before it came to too great a head, both the Maffsefylian and Carthaginian ftates would be infallibly con fumed by it.” Syphax, alarmed by thefe fuggeftions, advanced with a numerous body of forces into a diftridt which had long been in difpute between him and Gala, but was then in poffeflion of Mafinifla. This brought on a general aftion betw'een thefe two princeswherein the latter was totally de¬ feated, his'army difperfed, and he himfelf obliged to fly to the top of Mount Balbus, attended only by a few of his horfe. Such a decifive battle at the prefent jundlure, before Mafiniffa was fixed in his throne, could not but put Syphax into poffeflion of the kingdom of the Maf¬ fyli. Mafinifla in the mean time made nodlurnal incur- fions from his poft upon Mount Balbus, and plundered all the adjacent country, particularly that part of the Carthaginian territory contiguous to Numidia. This diftridl he not only thoroughly pillaged, but likewife laid wafte with fire and fword, carrying off from thence an N U M [ | Kumidia. an immenfe booty, which was bought by Tome mer- v chants, who had put into one of the Carthaginian ports for that purpofe. In fine, he did the Carthaginians more damage, not only by committing fuch dreadful devafta- tions, but by maffacring and carrying into gaptivity vaft numbers of their fubjects on this occafion, than they could have fuftained in a pitched battle, or one cam¬ paign of a regular war. Syphax, at the prefiing and reiterated infiances of the Carthaginians, fent Bocchar, one of his molt aftive commanders, with a detachment of 4000 foot, and 2000 horfe, to reduce this pefiilent gang of robbers, promifing him a great reward if he could bring Mafiniffa either alive or dead. Bocchar, watching an opportunity, furprifed the Maffylians, as they were draggling about the country without any or¬ der or difcipline ; fo that he took many prifoners, dif- perfed the reft, and purfued Mafiniffa himfelf, with a few of his men, to the top of the mountain Avhere he had before taken poft. Confidering the expedition as ended, he not only fent many head of cattle, and the other booty that had fallen into his hands, to Syphax, but likewife all the force, except 500 foot and 200 horfe. With this detachment he drove Mafiniffa from the fummit of the hill, and purfued him through feveral narrow paffes and defiles, as far as the plains of Clupea. Here he fo furrounded him, that all the Maffylians, ex¬ cept four, were put to the fword, and Mafiniffa himfelf, after having received a dangerous wound, efcaped with the utmoft difficulty. As this was effe&ed by crofting a rapid river, in which attempt two of his four attend¬ ants periftied in the fight of the detachment that pur¬ fued him, it was rumoured all over Africa, that Mafi¬ niffa alfo was drowned •, which gave inexpreflible plea- fure to Syphax and the Carthaginians. For fome time he lived undifcovered in a cave, where he was fupported by the robberies of the two horfemen that had made their efcape with him. But having cured his wound by the application of fome medicinal herbs, he boldly be¬ gan to advance towards his own frontiers, giving out publicly that he intended once more to take poffeftion of his kingdom. In his march he was joined by about 40 horfe, and, foon after his arrival amongft the Maffyli, fo many people flocked to him from all parts, that out of them he formed an army of 6000 foot and 4000 horfe. With thefe forces, he not only reinftated him¬ felf in the poffeflion of his dominions, but likewife laid warte the borders of the Maffaefyli. This fo irritated Syphax, that he immediately affembled a body of troops, and encamped very commodieufty upon a ridge of mountains between Cirta and Hippo. His army he commanded in perfon ; and detached his fon Vermina, #with a confiderable force, to take a compafs, and attack the enemy in the rear. In purfuance of his orders, Vermina fet out in the beginning of the night, and took poft in the place appointed him, without being dif- covered by the enemy. In the mean time Syphax de¬ camped, and advanced towards the Maffyli, in. order to give them battle. When he had poffeffed himfelf of a rifing ground that led to their camp, and conclu¬ ded that his fon Vermina muft have formed the ambuf- cade behind them, he began the fight. Mafiniffa being advaiftageoufly ported, and his foldiers diftinguiffiing themfelves in an extraordinary manner, the difpute was long and bloody. But Vermina unexpectedly falling upon their rear, and by this means obliging them to )i ] N U M divide their forces, which were fcarcely able before to Numidia. oppofe the ihain body under Syphax, they were foonv~—“ thrown into confufion, and forced to betake themfelves to a precipitate flight. Ail the avenues being blocked up, partly by Syphax, and partly by his fon, fuch a dreadful flaughtei? was made of the unhappy Maffyli, that only Mafiniffa himfelf, with 60 horfe, efcaped to the Leffer Syrtis. Here he remained, betwixt the con¬ fines of the Carthaginians and the Garamantes, till the arrival of Laelius and the Roman fleet on the coaft of Africa. What happened immediately after this junClion with the Romans, belongs to the article Rome. It will be fufficient, therefore, in this place to ob- ferve, that, by the aftiftance of Ltelius, Mafiniffa at laft reduced Syphax’s kingdom. According to Zonaras, Mafiniffa and Scipio, before the memorable battle of Zama, by a ftratagem, deprived Hannibal of fome ad¬ vantageous ports; which, with a folar eclipfe happening during the heat of the aCtion, and not a little intimidat¬ ing the Carthaginian troops, greatly contributed to the victory the Romans obtained. At the conclufion there¬ fore of the fecond Punic war, he was amply rewarded by the Romans for the important fervices he had done them. As for Syphax, after the lofs of his dominions, he was kept in confinement for fome time at Alba ; from whence being removed in order to grace Scipio’s triumph, he died at Tibur in his way to Rome. Zo¬ naras adds, that his corpfe was decently interred ; that all the Numidian prifoners were releafed ; and that Vermina, by the aftiftance of the Romans, took peace¬ able poffeflion of his father’s throne. However, part of the Maffaefylian kingdom had been before annexed to Mafiniffa’s dominions, in order to reward that prince for his Angular fidelity and elofe attachment to the Romans. This feems to be countenanced by the epitomizer of Livy, who gives us fufficiently to underftand, that Sy¬ phax’s family, for a confiderable time after the conclu¬ fion of the fecond Punic war, reigned in one part of Numidia. For he intimates, that Archobarzanes, Sy¬ phax’s grandfon, and probably Vermina’s fon, hovered with a powerful army of Numidians upon the Cartha¬ ginian frontiers a few years before the beginning of the third Punic Avar. This he feems to have done, either in order to cover them, or to enable the Cartha¬ ginians to make an irruption into Mafiniffa’s territo¬ ries. Cato, hoAvever, pretended that thefe forces, in conjundfion with thofe of Carthage, had a defign to in¬ vade the Roman dominions, which he urged as a reafon to induce the confcript fathers to deftroy the African republic. Nothing is further requifite, in order to complete the hiftory of this famous prince, than to exhibit to our readers vieAV fome points of his condudl toAvards the de¬ cline, and at the elofe, of life ; the wife difpofitions made after his death by AEmilianus, in order to the re¬ gulation of his domeftic affairs; and fome particulars relating to his charadler, genius, and habit of body, draAvn from the moft celebrated Greek and Roman au¬ thors. By draAving a line of circumvallation around the Carthaginian army under Afdrubal, ported upon an eminence, Mafiniffa cut off all manner of fupplies from them; which introduced both the plague and famine into their camp. As the body of Numidian troops em- M 2 ployed N U M [9: .Vumidia. ployed In tills blockade ^vas not near fo numerous as 1 'v " the Carthaginian forces, it is evident, that the line here mentioned mull have been extremely llrong, and con- fequently the effeft of great labour and art. The Carthaginians, finding themfelves reduced to the lall extremity, concluded a peace upon the following terms, which Mafiniffa diftated to them : I. That they ihould deliver up all deferters. 2. 1 hat they fhould recal their exiles, who had taken refuge in his domi¬ nions. 3. That they fhould pay him 5000 talents of filver within the fpace of 50 years. 4' ihat their foldiers Ihould pafs under the jugum, each of them car- rying off only a fingle garment. As Mafiniffa him- felf, though between 80 and 90 years of age, conduc¬ ted the whole enterprife, he mull have been extremely well verfed in fortification, and other branches of the military art. His underilanding likewife he muff have retained to the lall. I his happened a fhort time before the beginning of the third Punic war. See 5 Carthage. Mafiniffa Soon after, the confuls landed an army in Africa, in difpleafed on]er to ’iay fiege to Carthage, without imparting to TionKi-i® Mafiniffa their defign. This not a little chagrined xomai.s, a? jt was contrary to the former practice of the Romans 5 who, in the preceding war, had communicat¬ ed their intentions to him, and confulted him on all occafions. When, therefore, the confuls applied to him for a body of his troops to a<5t in concert with their forces, he made anfwer, “ That they fiiould have a^ re¬ inforcement from him when they flood in need of it.” It could not but be provoking to him to confider, that after he had extremely weakened the Carthaginians, and even brought them to the brink of ruin, his pre¬ tended imperious friends fhould come to reap the fruits of his viftory, without giving him the leaft intelligence of it. However, his mind foon returned to its natural bias, which was in favour of the Romans. Finding his end approaching, he fent to ./Emilianus, then a tribune in the Roman army, to defire a vifit from him. What he propofed by this vifit, was to inveft him with full powers to difpofe of his kingdom and eftate as he fliould think proper, for the benefit of his children. The high idea he had entertained of that young hero’s abi¬ lities and integrity, together with his gratitude and af- feflion for the family into which he was adopted, in- hnt le6aves duced him to take this ftep. But, believing that death every thing would not permit him to have a perfonal conference to the dif- with /Emilianus upon this fubjeft, he informed his wife pofal of JE- an(j children in his laft moments, that he had empower- jnihatius. e(j to difpofe in an abfolute manner of all his pof- feffions, and divide his kingdom amongft his fons. To which he fubjoined, “ I require, that whatever Almi- lianus may decree, fliall be executed as pundually as if I myfelf had appointed it by my will.” Having uttered thefe words, he expired, at about 90 years of age. This prince, during his youth, had met with ftrange reverfes of fortune. However, fays Appian, being fupported by the Divine proteftion, he enjoyed an un¬ interrupted courfe of profperity for a long feries of years. His kingdom extended from Mauritania to the weftern confines of Cyrenaica j from whence it ap¬ pears, that he was one of the mod powerful princes of Africa. Many of the inhabitants of this vaft tra£l he civilized in a wonderful manner, teaching them to cul- t ] N U M tivate their foil, and to reap, thofe natural advantages NumiJia. which the fertility of fome parts of their country of-v—« fered them. He was of a more robuft habit of body than any of his cotemporaries, being bleffed with the greateft health and vigour 5 which was doubtlefs owing to his extreme temperance, and the toils he inceffantly fuftained. We are informed by Polybius, that fome- times he flood upon the fame fpot of ground from mor¬ ning till evening, without the leaft motion, and at others continued as long in a fitting pofture. He would remain on horfeback for feveral days and nights together, without being fenfible of the leaft fatigue. Nothing can better evince the ftrength of Iris conttitution, than his youngeft fon, named Stembal, Sthemba, or Stembanusy who was but four years old at his deceafe. 1 hough 90 years of age, he performed all the exercifes ufed by young men, and always rode without a laddie. Pliny tells us, that he reigned above 60 years. He was an able commander, and much facilitated the redu&ion of Carthage. Plutarch from Polybius obferves, that the day after a great viftory won over the Carthaginians, Mafiniffa was feen fitting at the door of his tent, eating a piece of brown bread. Suidas relates, that to the laft he could mount his horfe without any alfiftancc- According to Appian he left a numerous w-ell difeiplined army, and an immenie quantity of wealth, behind him. Mafiniffa, before his death, gave his ring to his eldefi: fon Micipfa 5 -but left the diftributicn of all his other effe&s and poffeffions amongft his children entirely to iEmilianus. Of 54 fons that furvived him, only three were legitimate, to wit, Micipfa, Gulufla, and Mafia- nabal. iEmilianus, arrived at Cirta after he had ex¬ pired, divided his kingdom, or rather the government of it, amongft thefe three, though to the others he gave confiderable poffeflions. To Micipfa, who was a prince of a pacific difpofition, and the eldeft fon, he affigned Cirta, the metropolis, for the place of his refidence,. in exclufion of the others. Guluffa, the next to him, being a prince of military genius, had the command of the army, and the tranfadting of all affairs relating to peace or war committed to his care. And Maftanabal, the youngeft, bad the adminiftration of juftice, an employment fuitable to his education, allotted him. They enjoyed in common the immenfc treafures Mafiniffa had amaffed, and were all of them dignified by iEmi- lianus with the royal title. After he had made thefe wife difpofitions, that young nobleman departed from Cirta, taking with him a body of.Numidian troops, under the conduft of Guluffa, to reinforce the Roman army that was then a&ing againft the Carthaginians. Maftanabal and Guluffa died foon after their father, as appears from the exprefs teftimony of Salluft. W# find nothing more remarkable of thefe princes, befides what has been already related, than that the latter con¬ tinued to afiift the Romans in the third Punic v'ar, and that the former was pretty well verfed in the Greek language. Micipfa therefore became foie poffeffor of the kingdom of Numidia. In his reign, and under the con- fulate of M. Platius Hypfaeus and M. Fulvius Flaccus, according to Orofius, a great part of Africa V'as co¬ vered with locufts, which deftroyed all the produce of the earth, and even devoured dry wood. But at laft they were all carried by the wind into the African fea, out of which being thrown in vaft heaps upon the Ihore, a plague enfued which fwept away an infinite number Hiftory of Jugurtha. N U M Ntimklia. number of animals of all kinds. In • V ' 800,000 men perilhed, and in Africa Propria 200,000 ; amongft the reft, 30,000 Roman foldiers quartered in and about Utica for the defence of the latter province. At Utica, in particular, the mortality raged to fuch a degree, that 1500 dead bodies were carried out of one gate in a day. Micipfa had two fons, Adherbal and Hiempfal, whom he educated in his palace, together with his nephew Jugurtha. That young prince was the fon of Maftanabal •, but his mother having been only a concubine, Mafiniffa had taken no great notice of him. However, Micipfa confidering him as a prince of the blood, took as much care of him as he did of his 7 own children. Jugurtha poffeffed feveral eminent qualities, which gained him univerfal efteem. He was very handfome, endued with great ftrength of body, and adorned with the fineft intelleffual endowments. He did not devote himfelf, as young men commonly do, to a life of luxury and pleafure. He ufed to exercife himfelf, with perfons of his age, in running, riding, hurling the javelin, and other manly exercifes, fuited to the martial genius of the Numidians *, and though he furpaffed all his fel¬ low fportfmen, there was not one of them but loved him. The chafe was his only delight ; but it was that of lions and other favage bealfs. Salluft, to finifh his character, tells us, that he excelled in all things, and fpoke very little of himfelf. So confpicuous an affemblage of fine talents and per- fe&ions, at firft charmed Micipfa, who thought them an ornament to his kingdom. However, he foon be¬ gan to refledf, that he was contiderably advanced in years, and his children in their infancy ; that mankind naturally thirfted after power, and that nothing was capable of making men run greater lengths than a vi¬ cious and unlimited ambition. Thefe reflexions foon excited his jealoufy, and determined him to expofe Ju¬ gurtha to a variety of dangers, fome of which, he en¬ tertained hopes, might prove fatal to him. In order to this, he gave him the command of a body of forces which he fent to aflift the Romans, who wrere at that time befieging Numantia in Spain. But Jugurtha, by his admirable conduX, not only efcaped all thofe dan¬ gers, but likewife won the efteem of the whole army, and the friendfhip of Scipio, who fent a high charac¬ ter of him to his uncle Micipfa. However, that ge¬ neral gave him fome prudent advice in relation to his future conduX •, obferving, no doubt, in him certain fparks of ambition, which, if lighted into a flame, he apprehended might one day be produXive of the moft fatal confequences. Before this laft expedition, Micipfa had endeavour¬ ed to find out fome method of taking him off private¬ ly *, but his popularity amongft the Numidians obliged that prince to lay afide all thoughts of this nature. After his return from Spain the whole nation almoft adored him. The heroic bravery he had fhown there, his undaunted courage, joined to the utmoft calmnefs of mind; which enabled him to preferve a juft medium between a timorous forefight and an impetuous rafh- nefs, a cireumftance rarely to be met with in perfons of his age, and above all the advantageous teftimo- nials of his conduX given by Scipio, attraXed an uni¬ verfal efteem. Nay, Micipfa himfelf, charmed with the high opinion, the Roman general had entertained of [ 93 ] N U M Numidia only his merit, changed his behaviour towards him 5 refolv- NumiJia^ ing, if poflible, to win his affeXion by kindnefs. He * therefore adopted him, and declared him joint heir with his two fons to the crown. Finding, fome few years afterwards, that his end approached, he fent for all three to his bed fide j where, in the prefence of the whole court, he defired Jugurtha to recolleX with what extreme tendernefs he had treated him, and confequent- ly to confider how well he had deferved at his hands. r> He then entreated him to proteX his children on allwllo n^- occafions ; who, being before related to him by the^^ ®®^ 8 Is dreaded by King Micipfa, ties of blood, were now by their father’s bounty be- with the come his brethren. In order to fix him the more firmly Care of his in their intereft, he likewife complimented him upon children; his bravery, addrefs, and confummate prudence. He further infinuated, that neither arms nor treafures con- ftitute the ftrength of a kingdom ; but friends, who are neither won by arms nor gold, but by real fervices and an inviolable fidelity. “ Now, where (continued he) can we find better friends than in brothers ? And how can that man who becomes an enemy to his rela¬ tions, repofe any confidence in, or depend upon ftran- gers ?” Then addrefling himfelf to Adherbal and Hi¬ empfal, “ And you (faid he) I enjoin always to pay the higheft reverence to Jugurtha. Endeavour to imi¬ tate, and if poflible furpafs, his exalted merit, that the world may not hereafter obferve Micipfa’s adopted fon to have refleXed greater glory upon his memory than his own children.” Soon after, Micipfa, who, accord¬ ing to Diodorus, was a prince of an amiable charaXer, expired. Though Jugurtha did not believe the king to fpeak his real fentiments with regard to him, yet he feemed extremely pleafed with fo gracious a fpeech, and made him an anfwer fuitable to the occafion. However, that prince at the fame time was determined within himfelf to put in execution the fcheme he had formed at the fiege of Numantia, which was fuggefted to him by fome faXious and abandoned Roman offi¬ cers, with whom he there contraXed an acquaintance. The purport of this fcheme was, that he ftiould extort the crown by force from his two coufins, as foon as their father’s eyes were clofed *, which they infinuated might cafily be effeXed by his own valour, and the venality of the Romans. Accordingly, a ftiort time after the old king’s death, he found means to aflaffi- 10 nate Hiempfal in the city of Thirmida where his trea- one of fures were depofited, and drive Adherbal out of his^10™*16 dominions. That unhappy prince found himfelf obli- anc} ^r-Y’ . ged to fly to Rome, where he endeavoured to engage out th« the confcript fathers to efpoufe his quarrel ; but, not- other, withftanding the juftice of his caufe, they had not vir¬ tue enough efteXually to fupport him. Jugurtha’s am- baffadors, by diftributing vaft fums of money amongft: the fenators, brought them fo far over, that a majority palliated his inhuman proceedings. This encouraged thofe minifters to declare, that Hiempfal had been killed by the Numidians on account of his exceffive cruelty; that Adherbal was the aggreffor in the late troubles ; and that he was only chagrined becaufe he could not make that havock among his countrymen he would willingly have done. They therefore entreated the fenate to form a judgment of Jugurtha’s behavour in Africa from his conduX at Numantia, rather than from the fuggeftions of his enemies. Upon which, by far the greateft part of the fenate difeovered themfelves prejudiced N U M C 94 ] N U M the Ro. mans. Numidta. prejudiced in his favour. A few, however, that were * " 1 not loft to honour, nor abandoned to corruption, infifted upon bringing him to condign punifhment. But as they could not prevail, he had the beft part of Numidia allotted him, and Adherbal was forced to reft fatisfied TI with the other. Venality of Jugurtha finding now by experience that every thing was venal at Rome, as his friends at Numantia had before informed him, thought he might purfue his towering projects without any obftrudtion from that quarter. He therefore, immediately after the laft di- vifion of Micipfa’s dominions, threw off the mafk, and attacked his coufin by open force. As Adherbal was a prince of a pacific difpofition, and almoft in all re- fpe&s the reverfe of Jugurtha, he Was by no means a match for him. The latter therefore pillaged the for¬ mer’s territories, ftormed feveral of his fortreffes, and overran a good part of his kingdom without oppofitiop. Adherbal, depending on the friendfhip of the Romans, which his father in his laft moments affured him would be a ftronger fupport to him than all the troops and treafures in the univerfe, defpatched deputies to Rome to complain of thefe hoftilities. But whilft he loft his time in fending thither fruitlefs deputations, Jugur¬ tha overthrew him in a pitched battle, and foon after ihut him up in Cirta. During the fiege of this city, a Roman commiflion arrived there, in order to perfuade both parties to an accommodation ; but finding Jugur¬ tha untraftable, the commiflioners returned home with¬ out fo much as conferring with Adherbal. A fecond deputation, compofed of fenators of the higheft diftinc- tion, with ALmilius Scaurus, prefident of the fenate, at their head, landed fome time after at Utica, and fum- moned Jugurtha to appear before them. That prince at firft feemed to be under dreadful apprehenfions, efpe- ckdly as Scaurus reproached him with his enormous crimes, and threatened him with the refentment of the Romans if he did not immediately raife the fiege of Cirta. However, the Numidian, by his addrefs, and the irrefiftible power of gold, as was afterwards fu- fpefted at Rome, fo mollified Scaurus, that he left Adherbal at his mercy. In fine, Jugurtha had at laft Cirta furrendered to him, upon condition only that he Ihould fpare the life of Adherbal. But the mercilels tyrant, in violation of the laws of nature and humanity as well as the capitulation, when he had got poffeflion of the town, ordered him to be put to a moft cruel deatli. The merchants likewife, and all the Numidians in the place capable of bearing arms, he caufed without diftindlion to be put to the fword. Every perfon at Rome infpired with any fentiments of humanity, was ftruck with horror at the news of this tragical event. However, all the-venal fenators ftill concurred with Jugurtha’s minifters in palliating his enormous crimes. Notwithftanding which, the people, excited thereto by Caius Memmius their tri¬ bune, who bitterly inveighed againft the venality of the fenate, refolved not to let fo flagrant an inftance of villany go unpunifhed. This difpofition in them in¬ duced the confcript fathers likevvife to declare their intention to chaftife Jugurtha. In order to this, an army, was levied to invade Numidia, and the command of it given; to the conful Calpurnius Beftia, a perfon of good abilities* but rendered unfit for the expedition he was to go upon by his infatiable avarice. Jugurtha being informed of the great preparations making at NumiJia. Rome to attack his dominions, fent his fon thither to m avert the impending ftorm. The young prince was plentifully lupplied with money, which he had orders to diftribute liberally amongft the leading men. But Beftia, propofing to himfelf great advantages from an invafion of Numidia, defeated all his intrigues, and got a decree paffed, ordering him and his attendants to depart Italy in ten days, unlefs they were come to deliver up the king himfell, and all his territories, to the republic by way of dedition. Which decree being notified to them, they returned without fo much as having entered the gates of Rome j and the conlul foon after landed with a powerful army in Africa. For fome time he carried on the war there very brifkly, reduced feveral ftrong holds, and took many Numi¬ dians prifoners. But upon the arrival of Scaurus, a peace was granted Jugurtha upon advantageous terms. That prince coming from Vacca, the place of his refi- dence, to the Roman camp, in order to confer with Beftia and Scaurus, and the preliminaries of the trea¬ ty being immediately after fettled between them in private conferences, every body at Rome was convin¬ ced that the prince of the fenate and the conful had to their avarice facrificed the republic. The indigna¬ tion therefore of the people in general difplayed itlelf in the ftrongeft manner. Memmius alfo fired them with his fpeeches. It was therefore refolved to defpatch the praetor Caflius, a perfon they could confide in, to Numidia, to prevail upon Jugurtha to come to Rome, that they might learn from the king himfelf which of their generals and fenators had been feduced by the peftilenl influence of corruption. Upon his arrival there, he found means to bribe one Btebius Salca, a man of great authority amongft the plebeians, but of infatiable avarice, by whofe afliftance he efcaped with impunity. Nay, by the efficacy of gold, he not only eluded all the endeavours of the people of Rome to bring him to juftice, but likewife enabled Bomilcar, one of his attendants, to get Maffiva, an illegitimate fon of Micipfa, affaffinated in the ftreets of Rome. That young prince was advifed by many Romans of probity, wellwiftiers to the family of Mafiniffa, to apply for the kingdom of Numidia j which coming to Jugurtha’s ears, he prevented the ap¬ plication by this execrable ftep. However, he was ob¬ liged to leave Italy immediately. Jugurtha had fcarce fet foot in Africa, when he re¬ ceived advice that the fenate had annulled the ftrame- ful peace concluded with him by Beftia and Scaurus. Soon after, the conful Albinus tranfported a Roman army into Numidia, flattering himfelf with the hopes of reducing Jugurtha to reafon before the expiration of his confulate. In this, howrever, he found himfelf deceived; for that crafty prince, by various artifices fo amufed and impofed upon Albinus, that nothing of moment happen¬ ed that campaign. This rendered him ftrongly iufpeded of having betrayed his country, after the example of his predeceffors. His brother Aulus, who fucceeded him in the command of the army, was ftill more unfuccefsful; for after rifing from before. Suthul, where the king’s treafures w7ere depofited, he marched his forces into a defile, out of which he found it impoffible to extricate himfelf. lie therefore was obliged to fubmit to the ignominious ceremony of paffing under the jugum, with all his men, and to quit Numidia entirely in ten days time. N U M [ 9S ] N U M Metellus Numidia. time, in order to deliver his troops from immediate de- ItrufHon. The avaricious difpofition of the Roman commander had prompted him to befiege Suthul, the pofleflion of which place he imagined would make him mailer of all the wealth of .Tugurtha, and confequently paved the way to fuch a feandalous treaty. However, this was declared void as fooh as known at Rome, as being concluded without the authority of the people. The Roman troops retired into Africa Propria, which they had now reduced into the form of a Roman pro¬ vince, and there took up their winter quarters. In the mean time Cains Mamillius Limetanus, tri¬ bune of the people, excited the plebeians to inquire into the condufl of thofe perfons by whofe affiilance Jugurtha had found means to elude all the decrees of the fenate. This put the body of the people into a great ferment ; which occafioned a profecution of the guilty fenators, that was carried on, for fome time, with the utmoft heat and violence. Lucius Metellus the conful, during thefe tranfaclions, had Numidia afligned him for his province, and confequently was fentagainft appointed general of the army dellined to a£l againft Jugurtha. Jugurtha. As he perfcflly difregarded wealth, the Numidian found him fuperior to all his temptations j which was a great mortification to him. To this he joined all the other virtues which conftitute the great captain ; fo that .Tugurtha found him in all refpedls in- acceflible. That prince therefore was now forced to regulate his conduft according to the motions of Me¬ tellus, with the greateft caution ; and to exert his ut¬ moft bravery, in order to compenfate for that hitherto fo favourable expedient which now began to fail him. Marius, Metellus’s lieutenant, being likewife a perfon of uncommon merit, the Romans reduced Vacca, a large opulent city, and the moft celebrated mart in Numidia. They alfp defeated Jugurtha in a pitched battle ; overthrew Bomilcar, one of his generals, up¬ on the banks of the Muthullus ; and, in fine, forced the Numidian monarch to take fhelter in a place ren¬ dered almoft inacceffible bv the rocks and woods with which it was covered. However, Jugurtha fignalized himfelf in a furprifing manner, exhibiting all that could be expefted from the courage, abilities, and attention of a confummate general, to whom defpair adminifters freflr ftrength, and fuggefts new lights. But his troops could not make head againft the Romans } they rvere again worfted by Marius, though they obliged Metel¬ lus to raife the liege of Zama. Jugurtha, therefore, finding his country everywhere ravaged, his moft opu¬ lent cities plundered, his fortrefles reduced, his towns burnt, vaft numbers of his fubje&s put to the fword and taken prifoners, began to think ferioufiy of coming ^ to an accommodation with the Romans. JJis favourite Who is be- Bomilcar, in whom he repofed the higheft confidence, Eomilcw bllt 'vll° had been SaIned over t0 the enemy by Me¬ tellus, obferving this difpofition, found it no difficult matter to perfuade him to deliver up his elephants, money, arms, horles, and deferters, in whom the main ftrength of his army confifted, into the hands of the Romans. Some of thefe laft, in order to avoid the pu- nifhment due to their crime, retired to Bocchus king of Mauritania, and lifted in his fervice. But Metellus ordering him to repair to Tifidium, a city of Numidia, there to receive farther direftions, and he refufing a compliance wi th that order, hoftilities were renewed Numidia. T3 *4 with greater fury than ever. Fortune now feemed to declare in favour of Jugurtha : he retook Vacca, and maflacred all the Roman garrifon, except Turpilius the commandant. However, foon after,' a Roman le¬ gion feized again upon it, and treated the inhabitants with the utmoft feverity. About this time, one of Maf- tanabal’s fons, named Gauda, -whom Micipfa in his will had appointed to fucceed to the crown in cafe his two legitimate fons and Jugurtha died without iffue, wrote to the fenate in favour of Marius, who was then endeavouring to fupplant Metellus. That prince having his underftanding impaired by a de¬ clining ftate of health, fell a more eafy prey to the bafe and infamous adulation of Marius. The Roman, foothing his vanity, allured him, that as he was the next heir to the croWn, he might depend upon being fixed upon the Numidian throne, as Toon as Jugurtha was either killed or taken ; and that this mult in a ftrort. time happen, -when once he appeared at the head of the Roman army with an unlimited commiffion. Soon af- A ccmfpira- ter, Bomilcar and Nabdalfa formed a defign to aflaffinate againft Jugurtha, at the inftigatiqn of Metellus $ but this be- Im* ing detected, Bomilcar and moft of his accomplices fuf- fered death. The plot however had fuch an effe£t upon Jugurtha, that he enjoyed afterwards no tranquillity or repofe.' He fufpedled perfons of all denominations, Nu- midians as well as foreigners, of fome black defigns againft him. Perpetual terrors fat brooding over his mind ; infomuch that he never got a wink of fleep but by Health, and often changed his bed in a low plebeian manner. Starting from his lleep, he •would frequently fnatch his fword, and break out into the moft doleful cries : So ftrongly was he haunted by a fpirit of fear, jealoufy, and diftradlion ! Jugurtha having deftroyed great numbers of his friends on fufpicion of their having been concerned in the late confpiracy, and many more of them deferting to the Romans and Bocchus king of Mauritania, he found himfelf, in a manner, deftitute of counfellors, ge¬ nerals, and all perfons capable of affifting him in carry¬ ing on the war. This threw him into a deep melancho¬ ly, which rendered him diffatisfied with every thing, and made him fatigue his troops with a variety of contradic¬ tory motions. Sometimes he would advance with great celerity againft the enemy, and at others retreat with no fmall fwiftnefs from them. Then he refumed his former courage j but foon after defpaired either of the valour or fidelity of the forces under his command. All his movements therefore proved unfuceefsful, and at laft he was forced by Metellus to a battle. That part of the Numidian army which Jugurtha commanded, be¬ haved with fome refolution ; but the other fled at the firft onfet. The Romans therefore entirely defeated ^e* them, took all their ftandards, and made a few of them prifoners. But few of them were flain in the adlion __ fince, as Salluft obferves, the Numidians trufted more to their heels than to their arms for fafety in this en¬ gagement. Metellus purfued Jugurtha and his fugitives to Tha- la. His march to this place being through vaft de- ferts, was extremely tedious and difficult. But be¬ ing fupplied with leathern bottles and wooden veflels of all fizes taken from the huts of the Numidians, which were filled with water brought by the natives, who had fubmitted to him, he advanced towards the city. *5 Metellus, N U M [ 96 ■Ntxmidia. city. He had no fooner begun his march, than a moft s_ v copious iliower of rain, a thing very uncommon in thofe deferts, proved a great and feafonable refrelhment to his troops. This fo animated them, that upon their arrival before Thala, tliey attacked the town with fuch vigour, that Jugurtha with his family, and treafures dcpofited therein, thought proper to abandon it. Alter a brave defence, it was reduced } the garrifon, conliftingof Ro¬ man deferters, fetting lire to the king’s palace, and con- fuming themfelves, together with every thing valuable to them, in the flames. Jugurtha, being now reduced to great extremities, retired into Gsetulia, where he formed a conliderable corps. From thence he advanced to the confines of Mauritania •, and engaged Bocchus king of that country, who had married his daughter, to. enter into an alliance with him. In confequence of which, having reinforced his Gfetulian troops with a powerful body of Mauritanians, he turned the tables up¬ on Metellus, and obliged him to keep clofe within his , entrenchments. Salluft informs us, that Jugurtha brib¬ ed Bocchus’s miniflers to influence that prince in his favour } and that having obtained an audience, he inlinuated, that, fliould Numidia be fubdued, Mauri¬ tania mull be involved in its ruin, efpecially as the Ro¬ mans feemed to have vowed the deftruftion of all the thrones in the univerfe. In fupport of what he ad¬ vanced, he produced feveral inftances very appofite to the point in view. However, the fame author feems to intimate, that Bocchus was determined to aflift Ju¬ gurtha againit his enemies by the flight the Romans had formerly ihown him. lhat prince, at the firfl breaking out of the war, had lent ambalTadors to Rome, to propofe an offenfive and defenflve alliance to the re¬ public •, which, though of the utmofl: confequence to it at the junfture, a few of the moft yenal and infamous fenators, who were abandoned to corruption, prevent¬ ed from taking effeft. This undoubtedly wrought more powerfully upon Bocchus in favour of Jugurtha, than the relation he flood in to him : For both the Moors and Numidians adapted the number of their wives to their circumftances, fo that fome had 10, 20, &c. to their (hare •, their kings therefore w'ere unli¬ mited in this particular, and of cotirfe all degrees of af¬ finity refulting to them from marriage had little force. It is obfervable, that the pofterity of thofe ancient na¬ tions have the fame cuftom prevailing amongft them at this day. Marius fuc- Such was the fituation of affairs in Numidia, when ceeds Me- Metellus received advice of the promotion of Marius tellus. the confulate. But, notwithftanding this injurious treatment, he generoufly endeavoured to draw off Boc¬ chus from Jugurtha, though this would facilitate the re- duftion of Numidia for his rival. T- o this end ambaffa- dors were despatched to the Mauritanian court, who.in¬ timated to Bocchus, “ I nat it would be highly im¬ prudent to come to a rupture with the Romans without any caufe at all; and that he had now a fine opportuni¬ ty of concluding a mofl advantageous treaty with them, which was much preferable to a war. To which they added, that whatever dependence he might place upon his riches, he ought not to run the hazard of lofing his dominions by embroiling hirnfclf with other ftates, when he could eafily avoid this • that it was much eafier to begin a war than to end it, which it was in the power of the vi&or alone to do j that, in fine, he would by no ] N U M means confult the intereft of his fubjefb if he followed Numidia. the defperate fortunes of Jugurtha.” To which Boc-v—"Y*—" chus replied. “ That for his part there was nothing he wiflied for more than peace *, but that he could not help pitying the deplorable condition of Jugurtha ; that if the Romans, therefore, would grant that unfortunate prince the fame terms they had offered him, he would bring about an accommodation.” Metellus let the Mauritanian monarch know, that it was not in his power to comply with what he deflred. However, he took care to keep up a private negotiation with him till the new conful Marius’s arrival. By this conduct he ferved two wife ends. Firft, He prevented Bocchus from coming to a general adiion with his troops j which was the vciy thing Jugurtha defired, as hoping that this, whatever the event might be, would render a reconci¬ liation betwixt him and the Romans imprafticable. Se¬ condly, This in aft ion enabled him to difeover fomething of the genius and difpofition cf the Moors •, a nation of whom the Romans, till then, had fcarcely formed any idea 5 which, he imagined, might be of no fmall fervice, either to hirafelf or his fucceffors, in the future profe- cution of the war. Jugurtha, being informed that Marius, with a nu¬ merous army, was landed at Utica, advifed Bocchus to retire, with part of the troops, to fome place of dif¬ ficult accefs, whilft he himfelf took port upon another inacceflible fpot with the remaining corps. By this meafure, he hoped the Romans would be obliged to di¬ vide their forces, and confequently be more expofed to bis efforts and attacks. He likewife imagined, that fee¬ ing no formidable body appear, they would believe the. enemy in no condition to make head againit them j which might occafion a relaxation of difeipline, the ufu- al attendant of a too great fecurity, and confequently produce fome good effed. However, he was difappoint- ed in both thefe views. For Marius, far from fuffering a relaxation of difeipline to take place, trained up his troops, which confifted chiefly of new levies, in fo per- fed a manner, that they were foon equal in goodnefs to any confular army that ever appeared in the field. He alfo cut off great numbers of the Gcetulian marauders, defeated many of Jugurtha’s parties, and had like to have taken that prince himfelf near the city of Cirta. Thefe advantages, though not of any great importance, He ^ intimidated Bocchus, who now made overtures for an a ad- accommodation ; but the Romans, not being fufficiently vantage fatisfied of his fincerity, paid no great attention to them. o''er Jutul In the mean time Marius puflied on his conquefts, redu-' a‘ cing leveral places of lefs note, and at lall refolved to befiege Capfa. That this enterprife might be conduded with the greater fecrecy, he fuffered not the leafl hint of his defign to tranfpire, even amongft any of his offi¬ cers. On the contrary, in order to blind them, he de¬ tached A. Manlius, one of his lieutenants, with feme light-armed cohorts, to the city of Lares, where he had fixed his principal magazine, and depofited the military cheft. Before Manlius left the camp, that he might the more effedually amufe him, he intimated, that him¬ felf with the army ftiould take the fame route in a few days : but inftead of that, he bent his march towards the Tanais, and in fix days time arrived upon the banks of that river. Here he pitched his tents for a fhort time, in order to refrefti his troops *, which having done, he advanced to Capfa, and made himfelf mailer of it. * As N U M [ NumuTia. As tlie fituation of this city rendered it extremely com- modious to Jugurtha, 'whofe plan of operations, ever fince the commencement of the war, it had exceedingly favoured, he levelled it with the ground after it had been delivered up to the foldiers to be plundered. The citizens likewife, being more ftrongly attached to that prince than any of the other Numidians, on account of the extraordinary privileges he indulged them with, and of courfe bearing a more implacable hatred to the Romans, he put to the fvvord or fold for Haves. The true motive of the conful’s conduct on this occafion feems here to be afligned ; though we are told by Salluft, in conformity to the Roman genius, that neither avarice nor refentment prompted him to fo barbarous an ac¬ tion, but only a delire to Rrike a terror into the Numi¬ dians. The Numidians, ever after this exploit, dreaded the very name of Marius ; who now, in his own opinion, had eclipfed the glory of all his predecefibr’s great a- chievements, particularly the reduction of Thala, a city, in ftrength and fituation, nearly refembling Capfa, Fol¬ lowing his blow, he gradually prefented himfelf before moll of the places of ftrength in the enemy’s country j many of which either opened their gates, or were aban¬ doned, at his approach, being terrified rvith what had happened to the unfortunate citizens of Capfa. Others taken by force, he laid in alhes; and in ftiort, filled the greateft part of Numidia with blood, horror, and con- fufion. Then, after an obftinate defence, he reduced a caflle that feemed impregnable, feated not far from Mu- lucha, where .lugurtha kept part of his treafures. In the mean time, Jugurtha not being able to prevail upon Bocchus, by his repeated felicitations, to advance into Numidia, -where he found himfelf greatly prefled, Avas obliged to have recourfe to his ufual method of bribing the Mauritanian minifters, in order to put that prince in motion. He alfo promifed him a third part of his king¬ dom, provided they could either drive the Romans out of Africa, or get all the Numidian dominions confirmed to him by treaty. So confiderable a ceflion could not fail of engaging Rocchus to fupport Jugurtha Avith his Avhole power. The tAVo African monarchs, therefore, having joined their forces, furprifed Marius near Cirta as he was go¬ ing into Avinter quarters. The Roman general was fo pufhed on this occafion, that the barbarians thought themfelves certain of viftory, and doubted not but they 5 8 fhould be able to extinguilh the Roman name in Nu- igurtha midia. ]3ut their incaution and too great lecunty itirely de-enabled Marius to gRe them a total defeat; Avhich ated. -was folloAved four days after by fo complete an over¬ throw, that their numerous army, confifting of 90,000 men, by the acceflion bf a powerful corps of Moors, commanded by Bocchus’s fon Volux, Avas entirely ruin¬ ed. Sylla, Marius’s lieutenant, moft eminently diftin- guifhed himfelf in the laft aftion, which laid the founda¬ tion pf his future greatnefs. Bocchus, now looking upon Jugurtha’s condition as defperate, and not being Avilling to run the rilk of lofing his dominions, fhoAvcd a diipofition to clap up a peace Avith Rome. However, the republic gave him to underftand, that he muft not expeft to be^ ranked amongft its friends, till he had delivered up into the conful’s hands Jugurtha, the inve¬ terate enemy of the Roman name. The Mauritanian monarch, having entertained a high idea of an alliance Vol XV. Part I. 97 ] N U M Avith that ftate, refolved to fatisfy it in this particular ; 'Numicfia. and Avas confirmed in his refolution by one Dabar, a * ■' " Numidian prince, the fon of Maflugrada, and defeended by his mother’s fide from Mafinifla. Being clofely at¬ tached to the Romans, and extremely agreeable to Boc¬ chus, on account of his noble difpolition, he defeated all the intrigues of Alpar, Jugurtha’s minifter. Upon Syl- la’s arrival at the Mauritanian court, the affair there feemed to be entirely fettled. HoAArever, Bocchus, who Avas for ever projecting neiv defigns, and, like the reft of his countrymen, in the higheft degree perfidious, de¬ bated Avithin himfelf, Avhether he fhould facrifice Sylla or Jugurtha, Avho were both then in his poiver. He rvas a long time fluctuating Avith uncertainty, and combated by a contrariety of fentiments. The hidden changes which difplayed themfelves in his countenance, bis air, and his Avhole perfon, evidently (bowed Iioav ftrongly his mind Avas agitated. But at laft he returned to his firft de- fign, to Avhich the bias of his mind feemed naturally to lead him. He therefore delivered up Jugurtha into the hands of Sylla, to be conducted to Marius ; Avho, by that fuccefsful event, happily terminated this dangerous war. The kingdom of Numidia Avas ogav reduced to a new form: Bocchus, for his important fervices, had the country of the Maflaefyli, contiguous to Mauritania, af- v figned him : Avhich, from this time, took the name of New Mauritania. Numidia Propria, or the country of the Maffyli, Avas divided into three parts ; one of Avhich was given to Hiempfal, another to Mandreftal, both defeendants of MafiniiTa ; and the third the Romans an¬ nexed to Africa Propria, or the Roman province adja¬ cent to it. What became of Jugurtha after he had graced Marius’s triumph, at which ceremony he Avasled in chains, together Avith his two fons, through the ftreets of Rome, avc have already laid before our readers. See Jugurtha. jugurtha’s tA\m fons furvived him, but fpent their Tra. fac- lives in captivity at Venufia. However, one of them,ftorisafter named Oxyntas, Avas, for a ftiort time, releafed from neath o£ his confinement by Aponius, wlio befieged Acerrae jnJu§urtha’ the Avar betAveen the Romans and the Italian allies. 1 hat general brought this prince to his army, Avhere he treated him as king, in order to draAv the Numidian forces off from the Roman fervice. Accordingly thofe Numidians no fooner heard that the fon of their old king Avas fighting for the allies, than they began to defert by companies; which obliged Julius Ctefar the conful to part Avith all his Numidian cavalry, and fend them back into Africa. Some fevv years after this event, Pompey defeated Cneius Domitius Ahenobar- bus, and Hiarbas one of the kings of Numidia, kill¬ ing 17,000 of their men upon the fpot. Not fatisfied Avith this viftory, that general purfued the •fugitives to their camp, Avhich he foon forced, put Domitius to the fword, and took Hiarbas prifoner. He then reduced that part of Numidia Avhich belonged to Hiarbas, who feems to have fucceeded Mandreftal above-mentioned ; and gave it to Hiempfal, a neighbouring Numidian prince, defeended from Mafinifla, Avho had ahvays op- pofed the Marian faction. Suetonius informs us, that a difpute happened be-Csefar itt- tween Hiempfal and one Mafintha, a noble NumidianrnuU Juba, whom, it is probable, he had in fome tefpeff injured, when Julius Cmlar firft began to make a figure in the Avorld. The fame author adds, that CaTar Avarmly N efpoufed ' 'umidia. IT. Juba de¬ feats one of Csefar’s lieutenants. 1% Juba over¬ thrown by Cadar. N U M [ 98 ] efpoufcd the caufe of Mafintha, and even grofsly infult- lxru£tion. ed Juba, Hiempfal’a fon, when he attempted to vindi¬ cate his father’s condu£t on this occafion. He pulled him by the beard, than which a more unpardonable af¬ front could not be oftered to an African. In Ihort, he fcreened Mafintha from the infults and violence of his enemies 5 from whence a reafon may be affigned for Juba’s adhering fo clofely afterwards to the Pompeian faction. In confequence of the indignity Caefar had offered Juba, and the difpofition it had occafioned, that prince did Caefar great damage in the civil wars betwixt him and Pompey. By a llratagem he drew Curio, one of his lieutenants, into a general abfion, which it was his interell at that time to have avoided. He caufed it to be given out over all Africa Propria and Numidia, that he was retired into fome remote country at a great di- ftance from the Roman territories. This coming to Curio’s ears, who was then befieging Utica, it hin¬ dered him from taking the necefl'ary precautions againft a furprife. Soon after, the Roman general receiving in¬ telligence that a fmall body of Numidians was approach¬ ing his camp, he put himfelf at the head of his forces in order to attack them, and, for fear they (hould efcape, began his march in the night, looking upon himfelf as fure of viflory. Some of their advanced polls he fur- prifed alleep, and cut them to pieces •, which Hill farther animated him. In Ihort, about daybreak he came up with the Numidians, whom he attacked with great bra¬ very, though his men were then falling, and valfly fa¬ tigued by their forced and precipitate march. In the mean time, Juba, who immediately after the propagation of the rumour above mentioned, had taken care to march privately, with the main body of the Numidian army, to fupport the detachment fent before to decoy Curio, advanced to the relief of his men. The Romans had met with a great reliltance before he appeared ; fo that he ealily broke them, killed Curio, with a great part of his troops, upon the fpot, purfued the reft to their camp, which he plundered, and took many of them prifoners. Moll of the fugitives, who endeavoured to make their efcape on board the {hips in the port of Utica, were either llain by the purfuers, or drowned. The re¬ mainder fell into the hands of Varus, who would have faved them •, but Juba, who arrogated to hitnfelf the honour of this vidtory, ordered moll of them to be put to the fword. This vidlory infufed new life and vigour into the Pompeian fadfion, who thereupon conferred great ho¬ nours upon Juba, and gave him the title of king of all Numidia. But Csefar and his adherents declared him an enemy to the Rate of Rome, adjudging to Bocchus and Bogud, two African princes entirely in their in- tereft, the fovereignty of his dominions. Juba after¬ wards, uniting his forces with thofe of Scipio, reduced Caefar to great extremities, and would in all probabi¬ lity have totally ruined him, had he not been relieved by Publius Sittius. That general, having formed a confiderable corps, conlifting of Roman exiles, and Mau¬ ritanian troops fent him by Bocchus, according to Dio, or, as Caefar will have it, Bogud, made an irruption into Gaetulia and Numidia, while Juba was employed in Africa Propria. As he ravaged thefe countries in a dreadful manner, Juba immediately returned with the heft part of his army, to preferve them from utter de- *3 N U M However, Caefar knowing his horfe to be Nutnidia, afraid of the enemy’s elephants, did not think proper to Namifma. attack Scipio in the abfence of the Numidian, till his own elephants, and a frelh reinforcement of troops, v hourly expefted, arrived from Italy. With this accef- fion of ftrength, he imagined himfelf able to give a good account, both of the Roman forces with which he was to cope, and the barbarians. In the mean time Scipio defpatched reiterated expreffes to Juba to haften to his aftiitance *, but could not prevail upon him to move out of Numidia, till he had promifed him the pofleflion of all the Roman dominions in Africa, if they could from thence expel Csefar. This immediately put him in mo¬ tion j fo that, having fent a large detachment to make head againft Sittius, he marched with the reft of his troops to aflift Scipio. However, Csefar at laft over- threw Scipio, Juba, and Labienus, near the town of Thapfus, and forced all their camps. As Scipio was the ftrft furprifed and defeated, Juba fled into Numidia without waiting for Csefar’s approach} but the body of the Numidians detached againft Sittius, having been broken and difperfed by that general, none of his fub- jefls there would receive him. Abandoned therefore to defpair he fought death in a Angle combat with Pe- treius, and, having killed him, caufed himfelf to be def¬ patched by one of his Haves. After this decifive aftion, and the reduction of A- Nnmldia friea Propria, Caefar made himfelf mailer of Numidia, reduced to which he reduced to a Roman province, appointing ^ form Crifpus Salluftius to govern it in quality of proconful,a P10™1*’6* with private inftru£lions to pillage and plunder the in¬ habitants, and, by that means, put it out of their power ever to fliake off the Roman yoke. However, Bocchus and Bogud ftill preferved a fort of fovereignty in the country of the Maffaffyli and Mauritania, Ance the for¬ mer of thofe princes, having deferted Csefar, fent an ar¬ my into Spain to afliit the Pompeians y and the latter, with his forces, determined victory to declare for Csefar at the ever memorable battle of Munda. Bogud, after¬ wards Ading with Antony againft O&avius, fent a body of forces to aflift him in Spain 5 at which time the Tingi- tanians revolting from him, Bocchus, with an army com- pofed of Romans in the intereft of Odlavius, who paffed over from Spain into Africa, and his own fubje£ls, pof- feffed himfelf of Mauritania Tingitana. Bogud fled to Antony ; and Odftavius, after the conclufion of the war, honoured the inhabitants of Tingi with all the privileges of Roman citizens. He likewife confirmed Bocchus king of Mauritania Csefarienlis, or the country of the Maffsefyli, in the poffefiion of Tingitana, which he had conquered, as a reward for his important fervices. In this he imitated the example of his great predeceffor Julius Csefar, who divided fome of the fruitful plains of Numidia among the foldiers of P. Sittius, who had conquered great part of that country, and appointed Sittius himfelf fovereign of that diftrift. Sittius, as has been intimated above, having taken Cirta, killed Sabura, Juba’s general, entirely difperfed his forces, and either cut off or taken prifoners moft of the Pom¬ peian fugitives that efcaped from the battle of Thap- fus, highly deferved to be diftinguifhed in fo eminent a manner. After Bocchus’s death, Mauritania and the Maffsefylian Numidia were in all refpefts confidered as Roman provinces. NUMISMATOGRAPHIA, a term ufed for the defcriptioQ NUN [ Numifma- defcription and knowledge of ancient coins and medals, tographia whether of gold, filver, or brafs. See Coins and Me- ,T II D AES. . j ^‘n* , NUMITOR, the fon of Procas king of Alba, and the brother of Amulius. Procas before his death made him and Amulius joint heirs to the crown, on condition of their reigning annually by turns : but Amulius, on getting poffeffion of the throne, excluded Numitor, whofe fon Laufus he ordered to be put to death, and obliged Rhea Sylvia, Numitor’s only daughter, to be¬ come a veftal. This princefs becoming pregnant, de¬ clared that (he was with child by the god Mars j and afterwards brought forth Remus and Romulus, who at length killed Amulius, and reftored Numitor to the throne, 754 B. C. See Remus and Romulus. NUMMUS, a piece of money, otherwife called fejler- tius. NUN, the fon of Elifhamah, and father of Joflvja, of the tribe of Ephraim. The Greeks gave him the name of Nane inftead of Nun. This man is known in facred hiftory only by being the father of Jofhua. Nun, a woman, in feveral Chriftian countries, who devotes herfelf, in a cloifter or nunnery, to a religious life. See the article Monk. There were women, in the ancient Chriftian church, who made public profeftion of virginity, before the monaftic life was known in the world, as appears from the writings of Cyprian and Tertullian. Thefe, for dif- timftion’s fake, are fometimes called ecclefictjlical virgins, and w’ere commonly enrolled in the canon or matricula of the church. They differed from the monaftic virgins chiefly in this, that they lived privately in their fathers houfes, whereas the others lived in communities : but their profeilion of virginity was not fo ft rift as to make it criminal for them to marry afterwards, if they thought fit. As to the confecration of virgins, it had f . ne things peculiar in it: it was ufually performed publicly in the church by the bilhop. The virgin made a pub¬ lic profeffion of her refolution, and then the biftiop put upon her the accuftomed habit of facred virgins. One part of this habit was a veil, called the facrum vclamen ; another was a kind of mitre or coronet worn upon the head. At prefent, when a woman is to be made a nun, the habit, veil, and ring of the candidate are carried to the altar ; and the herfelf, accompanied by her neareft relations, is condufted to the bilhop, who, after mafs and an anthem, (the fubjeft of which is “ that Ihe ' ought to have her lamp lighted, becaufe the bridegroom is coming to meet her),” pronounces the benediftion; then Hie rifes up, and the bifliop confecrates the new habit, fprinkling it with holy water. When tire candi¬ date has put on her religious habit, Ihe prefents herfelf before the bilhop, and fings, on her knees, Ancilla Chrif- ti fum, &c. j then Ihe receives the veil, and afterwards the ring, by which Ihe is married to Chrift 5 and laftly, the crown of virginity. When (lie is crowned, an ana¬ thema is denounced againft all who (hall attempt to make her break her vows. In fome few inftances, per¬ haps, it may have happened that nunneries, monafteries, Sec. may have been ufeful as well to morality and reli¬ gion as to literature : in the grofs, however, they have been highly prejudicial', and however well they might be fuppofed to do when viewed in theory, in faft they are unnatural and impious. It was furely far from the intention of Providence to feolude youth and beauty in 99 ] N U O a cloiftered ruin, or to deny them the innocent en]'oy~ Nun meat of their years and fex. li NUNCIO, or Nuntio, an ambaffador from the pope k- ' to fome Catholic prince or ftate, or a perfon who at- tends on the pope’s behalf at a congrefs, or an aliemoly of leveral ambaffadors. NUNCUPATIVE, in the fchools, fomething that is only nominal, or has no exigence but in name. NUNCUPATIVE Will or Tejlament, a will made ver¬ bally, and not put in writing. See the articles W ile and Testament. NUNDINA, a goddefs among the ancient hea¬ thens, luppoicd to have the care of the purification of infants. And becaufe male infants were purified nine days after their birth, her name is derived from nonus, or the ninth, though female infants were purified the eighth day; which purification was called lujlration by the Romans. NUNDINAL, Nundinalis, a name which the Ro¬ mans gave to the eight firft letters of the alphabet ufed in their kalendar. This feries of letters, A, B, C, D, E, F, G, H, is placed and repeated fucceflively from the firft to the laft day of the year : one of thefe always exprefied the market days, or the affemblies called nundince, quaji no~ vending, becaufe they returned every nine days. The country people, aftef working eight days lucceflively, came to town the ninth, to fell their feveral commodi¬ ties, and to inform themfelves of what related to reli¬ gion and government. Thus the nundinal day being under A on the firft, ninth, feventeenth, and twenty- fifth days of January, &c. the letter D will be the nun¬ dinal letter of the year following. Thefe nundinals bear a very great refemblance to the dominical letters, which return every eight days, as the nundinals did every nine. NUNDOCOMAR, a Rajah in Bengal, and head of the Bramins, who, in 1775, was condemned to an ig¬ nominious death by Englilh laws newly introduced, in an Englilh court of juftice newly eftablilhed, for a for¬ gery charged to have been committed by him many years before. That he was guilty of the deed cannot be queftioned ; but there was furely fomething hard in condemning a man by an ex pojl fatto law. He bore his fate with the utmoft fortitude, in the full confidence that his foul would foon be reunited to the univerfal fpi- rit whence it had fprung. See Metaphysics, Part III. Chap. IV. Of the Immortality of the Soul. Monte NUOVO, in the environs of Naples, blocks up the valley of Averno. “ This mountain (Mr Swinburne tells us) arofe in the year 1538 ; for after repeated quakings, the earth burft afunder, and made way for a deluge of hot allies and flames, which riling extremely high, and darkening the atmofphere, fell down again and formed a circular mound four miles in circumfe¬ rence, and 1000 feet high, with a large cup in the middle. The wind riling afterwards, wafted the light¬ er particles oyer the country, blafted vegetation, and killed the animals who grazed ; the confequence was, that the place was deferted, till Don Pedro de Toledo, viceroy of Naples, encouraged the inhabitants by ex¬ ample and otherwife to return, “ Part of Monte Nuovo is cultivated, but the larger portion of its declivity is wildly overgrown with prickly broom, and rank weeds that emit a very fetid mlphu- N 2 reous N U R Monte reous fmell. The crater is {hallow, its infide clad with Nuoto jOhrubs, and the little area at the bottom planted with Nurem- % anc^ mulberry trees •, a moll ftriking fpecimen of the berg. amazing viciffitudes that take place in this extraordinay **■—vr-—country. I faw no traces of lava or melted matter, and few ftones within. “ Near the foot of this mountain the fubterraneous fires a6! with fuch immediate power, that even the fand at the bottom of the fea is heated to an intolerable de¬ gree.” NUPTIAL rites, the ceremonies attending the fo- lemnization of marriage, which are different in different ages and countries. We cannot omit here a cuftom which was praftifed by the Romans on thefe occafions; which was this : Immediately after the chief ceremonies were over, the new married man threw nuts about the room for the boys to fcramble for. Various reafons have been afiigued for it j but that which moil gene¬ rally prevails, and feems to be the moil juft, is, that by this aft the bridegroom fignified his relbluticn to aban¬ don trifles* and commence a ferious courfe of life ; whence nucibus reliciis in this fenfe became a proverb. They might alfo be an emblem of fertility. The ancient Greeks had a perfon to conduft the bride from her own to the bridegroom’s houfe \ and hence he was called by the Greeks Nijmphagogus, which term was afterwards ufed both by the Romans and the Jews. , NUREMBERG, an imperial city of Germany, ca¬ pital of a territory of the fame name, fituated in E. Long. II. N. Lat. 47. 30. It Hands on the Regnitz, over which it has feveral bridges, both of wood and Hone, at the bottom of a hill, 60 miles from Augf- burg, 87 from Munich, 46 from Wurtzburg, and 50 from Ratifbon •, and is thought by fome to be the Sego- dunum, and by others the Caftrum Noricum of the an¬ cients. The city has derived its name from the hill, upon which Hands this caftle, called, in Latin, Caftrum No¬ ricum, round which the city Avas begun to be built, and where the emperors formerly lodged ; and here they lodge ftill, when they pafs by that city. They there preferve, as precious relicks, the crown, fceptre, clothes, bufkins, and other ornaments of Charlemagne (a), which ferved alfo the emperor Leopold, when he went thither after his eleftion, to receive the homage of the city. The fmall river Regnitz, which runs through it, and thofe of Rednitz and Schivarzack, which pafs by its walls, furnilh the inhabitants, befides other advan¬ tages, with the means of making all forts of fluffs, dyes, and other manufaftures (b), and toys, which are car¬ ried and fold even in the Indies. N U R It is a large and ivell-built town, but not very popu- Nurem- lous. Its fortifications are a double wall, flanked with ^erg. torvers mounting cannon, and a deep ditch. The ma- giftrates, and moft of the inhabitants, are Lutherans. There are a great maiiy churches and chapels in it. In that of St Sebald is a brafs monument of the faint ; and a pifture, reprefenting the creation of the Avorld, by the celebrated Albert Durer, Avho was a native of the toAvn ; but the fineft church in the toAvn is that of St Giles. In that of the Holy Ghoft are kept moft of the jeAvels of the empire, together Avith the pretended fpear Avith which our Saviour’s fide AAras pierced, a thorn of his croAvn, and a piece of the manger wherein he ivas laid. Here are alfo a great many hofpitals, one in par¬ ticular for foundlings, and another for pilgrims j Avith H gymnafium, an anatomical theatre, a granary, a fine public library, the old imperial fortrefs or caftle, fome remains of the old citadel of the burgraves of Nurem¬ berg, feveral Latin Ichools, an academy of painting, a Avell furnilhed arfenal, a Teutonic houfe in Avhich the Roman Catholic fervice is tolerated, and a mint. Mr Keyfler fays, there are upAvards of 500 ftreets in it, about 140 fountains, 16 churches, 44 religious houfes, 12 bridges, 10 market places, and 25,000 inhabitants j and that its territories, befides the capital and four other towns, contain aboAre 500 villages, and about 160 mills on the Regnitz. The trade of this city, though upon the decline, is ftill very great, many of its manufaftures being ftill exported to all parts of the Avorld 5 among ' which may be reckoned a great variety of curious toys . in ivory, Avood, and metal, already mentioned. The city has alfo diftinguilhed itfelf in the arts of painting and engraA-ing. When the emperor Henry VI. aflifted at a tournament in Nuremberg, he railed 38 burghers to the degree of nobility, the defcendants of Avhom are called patricians, and have the government of the city entirely in their hands ; the Avhole council, except eight mailers of companies, Avho are fummoned only on extra¬ ordinary occafions, confilling of them. Among the fine brafs cannon in the arfenal, is one that is charged at the breech, and may be fired eight times in a mi¬ nute ; and tAvo that carry balls of eighty pounds. The city keeps, in conftant pay, feven companies, confifting each, in time of peace, of 100 men, but, in time of Avar, of 185 j tAvo troops of cuirafliers, each confifting of 85 men ; and tAvo companies of invalids. There are alfo 24 companies of burghers, Avell armed and difcip- lined. On the new bridge, which is faid to have coft 1 oo,oco guilders, are tAvo pyramids, on the top of one of which is a dove with an olive branch in her bill, and on the other an imperial black eagle. Mufic alfo flou- riflies greatly in Nuremberg ; and thofe Avho delight in mechanic [ 100 ] (a) Thefe ornaments are, a mitred croAvn, enriched with rubies, emeralds, and pearls ; the dalmatic of Char¬ lemagne, richly embroidered •, the imperial mantle powdered with embroidered eagles, and its border thick fet Avith large emeralds, fapphires, and topazes ; the bulkins covered with plates of gold ; the gloves embroidered j the apple, the golden fceptre, and fAvord. The ancient cuftom of the empire is, that the emperor is bound to af- femble in this city the firft diet that he holds after his eleftion and coronation. (B) T here is in Nuremberg, and in the neighbouring villages depending upon it, an infinite number of Avork- naen, very ingenious in making feveral kinds of toys of Avood, which are carried through all the fairs of Germany*, and from thence through all Europe. Thefe toys are called Nurembergs ; and they have fo great a fale, that it even exceeds defeription. This employment affords a livelihood to the greateft part of the inhabitants of the city y and they make a very confiderable profit from this traffic. 3 ■ Nurem¬ berg II Nurfing. NUB. f i mechanic arts and manufa&ures cannot anywhere bet¬ ter gratify their curiofity. As an imperial city, it has a feat and voice at the diets of the empire and circle, i paying to the chamber of Wetzlar 812 rixdollars each term. The territory belonging to the city is pretty large, containing, befides two confiderable forefts of pine, called the Sibald and Laurence forejls, feveral towns and villages. We have mentioned already that certain families cal¬ led patricians, to the exclufion of the reft, poflefs the offices of the fenate. They are compofed of 42 per- fons (c), over which two caftellans, or perpetual fe- nefchals, prefide, the firft of whom has his reftdence in the cattle. Thefe caftellans affemble fometimes in the cattle, with five or fix of the chief members, to hold a feerpt council (d). And, as this city glories in being one of the firft w'hich embraced Lutheranifm, it pre- ferves the privilege of that in civil matters, not admit¬ ting any Catholics to the magiftracy or freedom of the town *, the Catholics there having the liberty only of remaining under the protedtion of the reft, and perform¬ ing their religious worfhip in a commandery of Malta, and this but at certain hours, not to difturb the Luthe¬ rans, who likewife affemble there, although in poflef- iion of al] the other churches. This city is particularly noted for its antiquity, grandeur, fortifications, its triple walls of hewn ftone, its large and deep moat, its fine houfes, large churches, its wide ftreets, always clean, and for its curious and large library, and its magazine ftored with every thing proper for its defence. NURSERY, in Gardening, is a piece of land fet apart for raifing and propagating all forts of trees and plants to fupply the garden and other plantations. NURSING of Children. See Lactatio. The following obfervations and diredHons are faid to ^ An. Reg. be the refult of long experience f. The child ftiould be laid (the firft month) upon a thin mattrefs, rather longer than itfelf, which the nurfe will keep upon her lap, that the child may always lie ftraight, and only fit up as the nurfe flants the mattrefs. To fet a child quite upright before the end of the firft month, hurts the eyes, by making the white part of the eye appear be¬ low the upper eyelid. Afterwards the nurfe will begin to fet it up and dance it by degrees. The child muft be kept as dry as poflible. The clothing Ihould be very light, and not much longer than the child, that the legs may be got at with cafe, in order to have them often rubbed in the day with a warm hand or flannel, and in particular the in- fide of them. Rubbing a child all over takes off feurf, and makes the blood circulate. The one breaft fliould be rubbed with the hands one way, and the other the other way, night and morning at leaft. The ankle bones and infide of the knees fliould be vol. 13* 01 ] N U R rubbed twice a-day j this will {Lengthen thofe parts, Nurfing, and make the child ftretch its knees and keep them flat, which is the foundation of an dreft and graceful perfon. A nurfe ought to keep a child as little in her arms as poflible, left the legs ftiould be cramped, and the toes turned inwards. Let her always keep the child’s legs loofe. The oftener the pofture is changed, the better. Tofling a child about, and exercifing it in the open air in fine weather, is of the greateft fervice. In cities, children are not to be kept in hot rooms, but to have as much air as poflible. Want of exercife is the caufe of large heads, weak and knotted joints, a contrafted breaft, which occafions coughs and fluffed lungs, an ill-ftiaped perfon, and wad¬ dling gait, befides a numerous train of other ills. The child’s flefti is to be kept perfedlly clean, bv conftantly waffling its limbs, and likewife its neck and ears, beginning with warm water, till by degrees it ■will not only bear, but like to be walked with cold water. Riling early in the morning is good for all children, provided they awake of themfelves, which they gene¬ rally do : but they are never to be waked out of their lleep, and as foon as poflible to be brought to regular lleeps in the day. When laid in bed or cradle, their legs are always to be laid ftraight. Children, till they are two or three years old, muft never be fuffered to walk long enough at a time to be weary. Girls might be trained to the proper management of children, if a premium were given in free fchools, work- houfes, &c. to thofe that brought up the fineft child to one year old. If the mother cannot fuckle the child, get a ivhole- fome cheerful woman with young milk, who has been ufed to tend young children, After the firft fix months, fmall broths, and innocent foods of any kind, may do as well as living wholly upon milk. _ A principal thing to be always attended to is, to give young children conftant exercife, and to keep them in a proper pofture. With regard to the child’s drefs in the day, let it bo a fhirt 5 a petticoat of fine flannel, two or three inches longer than the child’s feet, with a dimity top (com¬ monly called a bodice coat), to tie behind ; over that a furcingle made of fine buckram, two inches broad, co¬ vered over with fatin or fine ticken, with a ribbon faft- ened to it to tie it on, which anfwers every purpofe of flays, and has none of their inconveniences. Over this put a robe,, or a flip and frock, or whatever you like beft ; provided it is faftened behind, and not much longer than the child’s feet, that their motions may be ftridtly obferved. Tivo (c) Of thefe 42 members, there are only 34 chofen from the patrician families j the other eight are taken from among the.burghers, and make in a manner a fmall feparate body. • ^ 1 his fecret.council is compofed of feven principal chiefs of the republic, and for that reafon is called feptem- virate. It determines the moft important affairs 5 and is the depofitory of the precious ftones. of the empire, of the- imperial crown, the enfigns, feals, and keys of the city. F ’ NUT [ 102 ] N U Y Tfurfing Two caps are to be put on the head, till the child has v A- teeth. ■J U ^-0n', The child’s drefs for the night may be a (hirt, a blanket to tie on, and a thin gown to tie over the blanket. NUSANCE, or Nuisance, in Law, a thing done to the annoyance of another. Nuifances are either public or private.—A public nuifance is an offence againfl: the public in general, ei¬ ther by doing what tends to the annoyance of all the king’s fubje&s, or by neglefting to do what the com¬ mon good requires : in which cafe, all annoyances and injuries to flreets, highways, bridges, and large rivers, as alfo diforderly alehoufes, bawdy-houfes, gaming houfes, ftages for rope-dancers, &c. are held to be com¬ mon nuifances.—A private nuifance is, when only one perfon or family is annoyed by the doing of any thing j as where a perfon flops up the light of another’s houfe, or builds in fuch a manner that the rain falls from his houfe upon his neighbour’s. NUT, among botanifts, denotes a pericarpium of an extraordinary hardnefs, enclofing a kernel or feed. NUTATION, in AJlronomy, a kind of tremulous motion of the axis of the earth, whereby, in each an¬ nual revolution, it is twice inclined to the ecliptic, and as often returns to its former pofition. NUTCRACKER. See Corvus, Ornithology Index. NUTHATCH. See Sitta, Ornithology Index. NUTMEG, the fruit of a tree, and a well known fpice. See Myristica. NUTRITION, in the animal economy, is the re¬ pairing the continual lofs which the different parts of the body undergo. The motion of the parts of the body, the fridlion of thefe parts with each other, and efpecially the aftion of the air, would deflroy the body entirely, if the lofs w’as not repaired by a proper diet, containing nutritive juices •, which being digeiled in the ftomach, and afterwards converted into chyle, mix with the blood, and are diflributed through the whole body for its nutrition. In young perfons, the nutritive juices not only ferve to repair the parts that are damaged, but alfo to increafe them which is called growth. In grown perfons, the cuticle is everywhere conflant- ly defquamating, and again renewing ; and in the fame manner the parts rubbed off, or otherwife feparated from the flelhy parts of the body, are foon fupplied with new flefli; a wound heals, and an emaciated perfon grows plump and fat. Buffon, in order to account for nutrition, fuppofes the body of an animal or vegetable to be a kind of mould, in which the matter neceffary to its nutrition is modelled and affimilated to the whole. But (con¬ tinues he) of what nature is this matter which an animal or vegetable aflimilates to its own fubftance ? What power is it that communicates to this matter the aiRivity and motion neceffary to penetrate this mould ? and, if fuch a force exift, would it not be by a fimilar force that the internal mould itfelf might be reproduced ? As to the firft queffion, he fuppofes that there exifts in nature an infinite number of living organical parts, and that all organized bodies confift of fuch organical parts $ that their production colls nature nothing, lince their exiftence is conftant and invariable j fo that the Nutritiofi matter which the animal or vegetable aflimilates to its II fubffance, is an organical matter of the fame nature , ^'U)ts' with that of the animal or vegetable, which confe- quently may augment its volume without changing its form or altering tire quality of the fubftance in the mould. As to the fecond queftion : There exift (fays he) in nature certain powers, as that of gravity, that have no affinity with the external qualities of the body, but aft upon the moft intimate parts, and penetrate them throughout, and which can never fall under the obfer- vation of our fenfes. And as to the third queftion, he anfwers, that the internal mould itfelf is reproduced, not only by a fimi¬ lar power, but it is plain that it is the very fame power that caufes the unfolding and reproduftion thereof: for it is fufficient (proceeds he), that in an organized body that unfolds itfelf, there be fome part fimilar to the whole, in order that this part may one day become it¬ felf. an organized body, altogether like that of which it is aftually a part. NUX MOSCHATA. See MyRISTICA. Nux Pijlachia. See Pistachia, Botany Index. NuX Vomica, a flat, compreffed, round fruit, about the breadth of a Ihilling, brought from the Eall Indies. It is found to be a certain poifon for dogs, cats, &c. and it is not to be doubted that it would alfo prove fatal to mankind. Its furface is not much corrugated 5 and its texture is firm like horn, and of a pale grayilh-brown. colour. It is faid to be ufed as a fpecific againft the bite of a fpecies of water-fnake. It is confiderably bit¬ ter and deleterious 5 but has been ufed in dofes from five to ten grains twice a-day or fo, in intermittents, parti¬ cularly obftinate quartans, and in contagious dyfentery. The Jinjchnus Ignatii is a tree of the fame kind, produ- cing gourd-like fruit, the feeds of which are improperly called St Ignatius’s beans. Thefe, as alfo the woods or roots of fome fuch trees, called lignum coluhrinum, or fnahewood, are very narcotic bitters, like the nux vo¬ mica. NUYTS, Peter, a native of Holland, and a lead¬ ing charafter in that extraordinary tranfaftion which happened between the Japanefe and the Dutch about the year 1628. In 1627 Nuyts arrived in Batavia from Holland, and was in the fame year appointed ambaffa- dor to the emperor of Japan by the governor and coun¬ cil of Batavia. He repaired to that empire in 1628 ; and being a man of a haughty difpofition, and extremely vain, he believed it prafticable to pafs upon the natives for an ambaffador from the king of Holland, Upon his af- fuming this title he was much more honourably received, careffed, and refpefted, than former minifters had been. But he was foon detefted, reprimanded, and reproach¬ ed in the fevereft manner, fent back to the port, and ordered to return to Batavia with all the circumftances of difgrace imaginable ; notwithftanding which, his iu- tereft was fo great, that, inllead of being punithed as he deferved, he was immediately afterwards promoted to the government of the iffand of Formofa, of which ho took poffeffion the year following. He entered upon the adminiftration of affairs in that ifland with the fame difpofition that he had fhown while ambaffador, and with the moft implacable refentment againft Nuyts II , Nychthe meron. NYC [ i againfl; the Japanefe 5 neither was it long before an op portunity offered, as he thought, of revenging bimfelf to the full. Two large Japanefe fhips, with upwards of 500 men on board, came into the port; upon which he took it into his head to difarm and unritj them, in the lame manner as the Dutch veffels are treated at Japan. The Japanefe did all they could to defend themfelves from this ill ufage j but at lall, for want of water, they were forced to fubmit. Governor Nuyts went ftill farther. When they had finifhed their affairs at For- mofa, and were defirous of proceeding, according to their inttruffions, to China, he put them off with fair words and fine promifes. till the monfoon was over. They began then to be very impatient, and defired to have their cannon and fails rcflored, that they might re¬ turn home 5 but the governor had recourfe to new arti¬ fices, and, by a feries of falfe promifes, endeavoured to hinder them from making ufe of the feafon proper for that voyage. The Japanefe, however, foon perceived his defign; and at length, by a bold attempt, accomplifhed what by fair means and humble entreaty they could not obtain ; for, by a daring and well concerted effort, they took him prifoner, and made him and one of the council fign a treaty for fecuring their liberty, free de¬ parture, and indemnity, which was afterwards ratified by the whole council. Nuyts was firfl confined in Ba¬ tavia, and afterw-ards delivered up to the Japanefe, not- withftanding the moft earneft entreaties on his part to be tried, and even to fuffer any kind of death where he was, rather than to be fent to Japan. He wras fent there, however, in 1634. was fubmitted to the mercy or difcretion of the emperor ; and the confe- quence was, that, though imprifoned, he was well ufed, and could go anywhere, provided his guards were with him, which was more than he could poffibly have ex- pefted. He now looked for nothing but the continu¬ ance of his confinement for life. On a particular occa- fion, however, i. e. at the funeral of the emperor’s father, at the requefl of the Dutch he was fet free, and returned again to Batavia, to the furprife of that people, Avho, however, adopted ever after a very different conduct with refpeft to the Japanefe. NUZZER,. or Nuzzeranah ; a prefent or offering from an inferior to a fuperior. In Hindoltan no man ever approaches Ids fuperior for the firft time on bufinefs without an offering of at leaft a gold or filver rupee in his right hand; which, if not taken, is a mark ofdif- favour. Nuzzeranah is alfo ufed for the fum paid to the government as an acknowledgement for a grant of lands or any public office. NYCHTHEMERON, among the ancients, figni- fied the whole natural day, or day and night confiftino- of 24 hours, or 24 equal parts. This way of confided mg the day was particularly adopted by the Jews, and feems to owe its origin to that expreffion of Mofes, in the firft chapter of Genefis, “ the evening and the morn¬ ing were the firft day.”—Before the Jews had introdu- ced the Greek hnguage into their difcourfe, they ufed to figmfy this fpace of time by the fimple expreffion of » night and a day. It is proper here to obferve, that all the eaftern countries reckoned any part of a day of 24 hours for a whole day ; and fay a thing that was done on the third or feventh day, &c. from that laft mentioned, was- 4 M And the Hebrews, Nychthe. Nymph. 03 ] NY done after three or feven days. ? having no word which exaftly anfwers to the Greek meron livyjmi^ov, fignifying “ a natural day of 24 hours,” ufe night and day, or day and night, for it. So that to i fay a thing happened after three days and three nights, was, with them, the fame as to fay it happened after three days, or on the third day. This, being remem¬ bered, will explain what is meant by “ the Son of Man’s being three days and three nights in the heart of the earth.” NYCTALOPIA. See Medicine, N° 361. NYC1 ANIHES, Arabian Jasmine, a genus of plants, belonging to the diandria clafs, and in the natu¬ ral method ranking with the 44th order, Sepiarice. See Botany Index. NYCTASTRATEGI, among the ancients, wmre officers appointed to prevent fires in the night, or to give alarm and call affiftance when a fire broke out. At Rome they had the command of the watch, and were called noBurni triumviri, from their office and number. NYCTICORAX, the night raven; a fpecies of Ardea. See Ardea, Ornithology Index. NYLAND, a province of Finland in Sweden, ly¬ ing on the gulf of Finland, to the weft of the province of Carelia. NYL-GHAU, a fp ecies of quadrupeds belonging to the genus Bos, a native of the interior parts of India. See Mammalia Index. NYMPH, in Mythology, an appellation given to certain inferior goddeffes, inhabiting the mountains, wood, waters, &c. faid to be the daughters of Oce- anus and lethys. All the univerfe was reprefented as full of thefe nymphs, who are diftinguiffied into feve- ral ranks or claffes. The general divifion of them is into celeftial and terreftrial; the former of them were called uranic?, and were fuppofed to be intelli¬ gences that governed the heavenly bodies or fpheres. , J he terreftrial nymphs, called epigeice, prefided over the feveral parts of the inferior world ; and were divi¬ ded into thofe of the water, and thofe of the earth. The nymphs of the water were the oceanitides, or nymphs- of the ocean ; the nereids, the nymphs of the fea; the naiads and ephydriades, the nymphs of the fountains; and the limniades, the nymphs of the lakes. The nymphs of the earth were the oreades, or nymphs of the moun¬ tains ; the napcece, nymphs of the meadows ; and the dryads and hamadryads, who were nymphs of the forefts and groves. Befides thefe, we meet with nymphs who took their names from particular countries, rivers, &c. as the eitheroniades, fo called from Mount Cithseron in Boeotia: the dodonides, from Dodona ; tiberiades, from the Tiber, &c.—Goats were fometimes facrifi- ced to the nymphs ; but their conftant offerings were '• milk, oil, honey, and wine. We have the following account of nymphs in Chand¬ ler’s Greece. “ They were fuppofed to enjoy longevity, but not to be immortal. They were believed to delight in fprings and fountains. They are deferibed as fleep- lefs, and as dreaded by the country people. They were- fufccptible of paffion. The Argonauts, it is related; landing on the fhore of the Propontis to dine m their way to Colchbs, fent Hylas, a boy for water, who dif-' covered a lonely fountain, in which the nymphs Eunica, . Mahs, and Nycheia, were preparing to dance; and thefe- feeing him were enamoured, .and, feizing him by th* hand N Y M [ 104 ] N Y M Nymph, hand as lie was filling his vafe, pulled him in. The dei- ■“"""v ties, their copartners in the cave, are fuch as prefided with them over rural and paftoral affairs. “ The old Athenians were ever ready to cry out, A god ! or a goddefs ! The tyrant Pififtratus entered the city in a chariot with a tall woman dreffed in ar¬ mour to refemble Minerva, and regained the Acropolis, which he had been forced to abandon, by this ftratagem ; the people worlhipping, and believing her to be the dei¬ ty wrhom fire reprefented. The nymphs, it wras the po¬ pular perfuafion, occafionally appeared 5 and nympho- lepfy is chara&erifed as a frenzy, which arofe from ha¬ ving beheld them. Superftition difpofed the mind to adopt delufion for reality, and gave to a fancied vifion the efficacy of full conviftion. The foundation was per¬ haps no more than an indire£f, partial, or obfcure view of fome harmlefs girl, who had approached the foun¬ tain on a like errand with Hylas, or was retiring after file had filled her earthen pitcher. “ Among the facred caves-on record, one on Mount Ida in Crete was the property of Jupiter, and one by Lebadea in Boeotia of Trophonius. Both thefe were oracular, and the latter bore fome refemblance to that we have defcribed. It was formed by art, and the mouth furrounded with a wall. 1 he defcent to the landing place was by a light and narrow ladder, occafionally applied and removed. It was fituated on a mountain above a grove ; and they related, that a fwarm of bees conduced the perfon by whom it was firfl: difcovered. But the common owners of caves were the nymphs, and thefe were fometimes local. On Cithseron in Boeo- tia, many of the inhabitants were poffeffed by nymphs called Sphragitides, whofe cave, once alfo oracular, was on a fummit of the mountain. Their dwellings had ge¬ nerally a w'ell or fpring of water ; the former often a colledlion of moifture condenfed or exuding from the roof and fides; and this, in many inftances, being pregnant with ffony particles, concreted, and marked its paffage by incruftation, the groundwork in all ages and coun¬ tries of idle tales framed or adopted by fuperftitious and credulous people. ' “ A cave in Paphlagonia was facred to the nymphs who inhabited mountains about Heraclea. It wTas long and wide, and pervaded by cold water, clear as cryftal. There alfo were feen bowls of ftone, and nymphs and their webs and diftaffs, and curious work, exciting admiration. The poet who has defcribed this grotto, deferves not to be regarded, as fervilely copying Homer •, he may juftly lay claim to rank as an original topographer. “ The piety of Archidamus furnifiied a retreat for the nymphs, where they might find Ihelter and provifion, if diftreffed ; whether the fun parched up their trees, or Jupiter enthroned in clouds upon the mountain top feared them with his red lightning and terrible thunder, pour¬ ing down a deluge of rain, or brightening the fummits with his fnow.” Nymph, among naturalifts, that ftate of winged in- fe£ls between their living in the form of a worm and their appearing in the winged or more perfeft ftate. The eggs of infers are firft hatched into a kind of worms or" maggots j which afterwards pafs into the nymph ftate, furrounded with ftiells or cafes of their own fkins } fo that, in reality, thefe nymphs are only the embryo infers, wrapt up in this covering •, from v'hence they at laft get loofe, though not without great Nymph difficulty. xr ^ 1 During this nymph ftate the creature lofes its motion. um Swammerdam calls it nympha aurelia, or limply aureiia; < y— and others give it the name of chrysalis, a term of the like import. See the article Chrysalis. Nymph-Band, fituated about 10 leagues off the coaft of the county of Waterford, and province of Mun- fter in Ireland, is a great filhing place, and 11 leagues S. S. E. from the high head of Dungarvan. It abounds with cod, ling, Ikate, bream, whiting, and. other fifii; which was difcovered by Mr Doyle, who on July 15. 1736 failed to it, in company with feven men, on board the Nymph, a fmall veffel of about 12 tons. This place is well adapted for a filhing com¬ pany, the great public advantages of which mull be very evident. NYMPHAS, in Anatomy, two membranaceous parts, fituated on each fide the rima. See Anatomy Index. v NYM PHAE A, the Water-lily 5 a genus of plants belonging to the polyandria clafs, and in the natural method ranking under the 54th order, Mifce/lanece. See Botany Index. Nymph.^ea (amongft the ancients), doubtful what ftrudlures they were ; fome take them to have been grottoes, deriving their name from the ftatues of the nymphs with which they were adorned ; but that they were eonfiderable works appears from their being ex¬ ecuted by the emperors, (Ammian, Vi&or, Capitolinus) or by the city prefers. In an infeription, the term is written nytnjium. None of all thefe nymphgea has lafted down to our time. Some years fince, indeed, a fquare building of marble was difcovered between Naples and Vefuvius, with only one entrance, and fome fteps that went down to it. On the right hand as you enter, towards the head, there is a fountain of the pureft water ; along which, by way of guard, as it were, is laid a naked Arethufa of the whiteft marble ; the bot¬ tom or ground is of variegated marble, and encompaffed with a canal fed by the water from the fountain : the ■walls are fet round with fiiells and pebbles of various co¬ lours ; by the fetting of which, as by fo many firokes in a picture, are expreffed the 12 months of the year, and the four political virtues ; alfo the rape of Proferpine ; Pan playing on his reed, and foothing his flock •, befides the reprefentations of nymphs fwimming, failing, and wantoning on fifties, &c. It feems pretty evident that the hymphoea were public baths \ for at the fame time that they were furnifiied with pleafing grottoes, they were alfo fupplied with cooling ft reams, by which they were rendered exceed¬ ingly delightful, and drew great numbers of people to frequent them. Silence feems to have been a particu¬ lar requifite there, as appears by this infeription, Nymphis loci, bibe, lava, tace. That building between Naples and Vefuvius, mentioned above, was certainly one of thefe nymphaea. NYMPPIAiUM, (Plutarch) ; the name of a facred place, near Apollonia in Ulyricum, fending forth con¬ tinually fire in detached ftreams from a green valley and verdant meadows. Dio Caffius adds, that the fire neither burns up nor parches the earth, but that herbs and trees grow and thrive near it, and therefore the place is called nymphccum : near which was an oracle of fuch a nature, that the fire, to ftiow that the wifti was granted t N Y M r 105 1 NYU Nymph®- granted, confumed the frankincenfe thrown into it : um- but repelled it, in cafe the defire was reje&ed. It was Nymph'- tjiere tjiat a fleepjng fatyr Was once caught and brought ‘hus' ■ Sylla as he returned from the Mithridatic war. This monfter had the fame features as the poets afcribe to the fatyr. He was interrogated by Sylla and by his interpreters*, but his articulations were unintelli¬ gible ; and the Roman fpurned from him a creature which feemed to partake of the nature of a bead more than that of a man. NyMPH/EUM, in antiquity, a public hall magnificent¬ ly decorated, for entertainments, &c. and where thofe who wanted convenience at home held their marriage feafts *, whence the name. NYMPH1DIUS, Sabinus, a perfon of mean de- feent, but appointed by Nero colleague of Tigellinus in the command of the praetorian guards. About the time, however, that the German legions revolted from this defpicable prince, he was alfo betrayed by Nymphi- dius and abandoned by his guards. Nymphidius began now to entertain thoughts of feizing the fovereignty himfelf. However, he did not immediately declare his ambitious views; but pretending to efpoufe the caufe of Galba, affured the guards that Nero was fled, and promifed them fuch firms as neither Galba nor any other was able to difeharge. This promife fecured for the prefent the empire to Galba, occafioned afterwards the lofs of it, and, finally, pro¬ duced the deftruftion of Nymphidius and the guards themfelves. After Nero’s death, however, and on the acknowledgement of Galba as emperor, he renewed his ambition ; and having, by his immenfe largeffes, gained the affections of the praetorian guards, and perfuading himfelf that Galba, by reafon of his infirmities and old age, would never reach the capital, ufurped all the authority at Rome. Prefuming upon his intereft, he obliged Tigellinus, who commanded, jointly with him, the praetorian guards, to refign his commiflion. He made feveral magnificent and extenfive entertainments, inviting fuch as had been confuls or had commanded armies, diftributed large firms among the people, and with Ihows and other diverfions, which he daily exhibit¬ ed, gained fo great an intereft: with all ranks, that he already looked upon himfelf as fovereign. The fenate, dreading his power, conferred extraordinary honours upon him, ftyled him their proteflor, attended him when he appeared in public, and had recourfe to him for the confirmation of their decrees, as if he had been already invefted with the fovereign power. This bafe com¬ pliance elated him to fuch a degree, that he ufurped Nymphfi not leifurely, and by degrees, but all at once, an ab- ‘Hi13 folute authority He aCled as fovereign indeed, but jgyU!.che. he had not as yet openly declared his defign of feizing ' .1—v— the empire: his power, however, was great, and he ufed it in undermining Galba’s power ; he was, how¬ ever, unfuccefsful, and the difclofure of his deiigns was much againft him. Galba was again acknowledged arid proclaimed, and he, notwithHanding his artifices, detefted and flain by the foldiers who were proclaiming Galba. See Nero. . NYON, a confiderable town of Switzerland, in the canton of Bern, and capital of a bailiwick of the fame name, with a caftle. It ftands delightfully upon the edge of the lake of Geneva, in the very point where it begins to widen, and in a moft charming country commonly called Pays de Vaud. It was formerly called Colonia Equejlris Noiodunum ; and, as a proof of its an¬ tiquity, feveral Roman inferiptions, and other ancient remains, have been frequently difeovered in the outikirts of the town. E. Long. 5. 10. N. Lat. 46. 24. NYSA, or Nyssa, in Ancient Geography, a torvn of Ethiopia, at the fouth of Egypt. Some place it in Arabia. This city, with another of the fame name in India, was facred to the god Bacchus, who was edu¬ cated there by the nymphs of the place, and who re¬ ceived the name of Dionysus, which feems to be com¬ pounded of Ares and Nv foft as to require it double, and that chiefly in the middle of words; as •goofe, reproof, &c. And in fome words, this 00 is pro¬ nounced like u fhort, as in blood, flood, &c, Vol. XV. Part I. ^ As a numeral, O was fometimes ufed for 11 among the ancients ; and with a dafti over it thus, o, for 11,000. In the notes of the ancients, O. CON is read opus conduclum ; O. C. £). opera confllioque; O. D. M. ope¬ ra, donum munus; and O. LO. opus locatum. O The OAK [ 106 ] OAK o, Oak. The Greeks had two O’e *, 'viz. omicran, a, and omega, m 4 the firft pronounced on the tip of the lips with a {harper found ; the fecond in the middle of the mouth, with a fuller found, equal to 00 in our lan¬ guage. The long and ihort pronunciation of our O are equivalent to the two Greek ones $ the fixft, as in fuppofe 5 the fecond, as in obey. O is ufually denoted long by a fervile a fubjoined, as moan ; or by e at the end of the fyllable, as bone; when thole •vowels are not ufed, it is generally flioft. Among the Irilh, the letter O, at the beginning of the name of a family, is a charafter of dignity annexed to great houfes. Thus, in the hiftory of Ireland, we frequently meet with the 0 Neals, 0 Cuito/s, Sec. con- fiderable houfes in that iiland. Camden obferves, that it is the cuftom of the lords ef Ireland to prefix an O to their names, to diliinguifli them from the commonalty. The ancients ufed O as a mark of triple time ; from a notion that the ternary, or number 3, was the moft perfect of numbers, and therefore properly expreffed by a circle, the moft perfect of figures. It is not, .itrhftly {peaking, the letter O, but the figure of a circle Q, or double C3, by which the mo¬ dern ancients in mufic ufed to exprefs what they called tcmiio perfeElo, or triple time. Hence the Italians call it circalo. The feven antiphones, or alternate hymns of feven verfes, &c. fung by the choir in the time of Advent, were formerly called 0, from their beginning with fuch an exclamation. O is an adverb of calling, or interjeclion of forrow or wilhing. OAK, in Botany. See Quercus. The oak has been long known by the title of -mo¬ narch erf the woods, and very juftly. It was well known, and often very elegantly deferibed, by the an¬ cient poets. The following defeription from Virgil is exquifite : Veluti annofo validam cum robore quercum Alpini Boreas, nunc hinc, nunc flatibus illinc Enuere inter fe certant: itjiridor, et alte Conjiernunt ten'am concujpo Jlipite frondes : Ipfa fucret fcopulis ; et quantum vertice ad auras JEithet'ias, tanium radice in Tart am, tendit. JEn. iv. 441. As o’er th’ aerial Alps fublimely fpread, Some aged oak uprears his reverend head ; This way and that the furious tempefts blow, To lay the monarch of the mountains low ; Th’ imperial plant, though nodding at the found, Though all his fcatter’d honours ftrew the ground j Safe in his ftrength, and feated on the rock, In naked majefty defies the (hock : High as the head {hoots tow’ring to the Ikies, So deep the root in hell’s foundation lies. Pitt. I he ancient druids had a moft profound veneration Oak, for oak trees. Pliny * fays, that “ the druids (as the — Gauls call their magicians or wife men) held nothing * NaU fo faered as the mifletoe, and the tree on which grows, provided it be an oak. They make choice of oak groves in preference to all others, and perform no rites without oak leaves 5 fo that they feem to have the name of druids from thence, if we derive their name from the Greek,” &c. (See Druids, Definition, and N° 11.) Maximus lyrius fays the Celtce or Gauls worftupped Ju¬ piter under the figure of a lofty oak (a). This ufeful tree grows to fuch a furprifing magni¬ tude, that were there not many well authenticated in- ftances of them in our own country, they would cer¬ tainly appear difficult of belief. In the 18th volume of the Gentleman’s Magazine we have the dimenfions. of a leaf twelve inches in length and feven in breadth, and all the leaves of the fame tree were equally large. On the eftate of Woodhall, purchafed in 1775 by Sir Thomas Rumbold, Bart, late governor of Madras, an oak was felled which fold for 43I. and meafured 24 feet round. We are alfo told of one in Millwood fo- reft, near Chaddefley, which was in full verdure in winter, getting its leaves again after the autumn ones fell off. In Hunter’s Evelyn’s Sylva, we have an ac¬ count of a very remarkable oak at Greendale 5 which Gough, in his edition of Camden, thus minutely de- feribes : The Greendale oak, with a road cut through it, ftill bears one green branch. Such branches as have been cut or broken off are guarded from wet by lead. The diameter of this tree at the top, whence the branches iffue, is 14 feet 2 inches; at the furface of the ground il.i4 feet 5 circumference there 35 feet 4 height of the trunk 53; height of the arch 10., width 6. Mr Evelyn mentions feveral more oaks of extraordinary fize.in Workfop park.” In the Gentleman’s Magazine for 1773 >.we have an account of one differing very effentially from the com¬ mon one; It is frequent about St Thomas in Devonfhire, and is in that county called Lucombe oak, from one William Lucombe who fuccelsfully cultivated it near Exeter. It grows as ftraight and handfome as a fir 4 its leaves are evergreen, and its wood as hard as that of the common oak. Its growth is fo quick, as to exceed in 20 or 30 years the altitude and girth iff the common one at iqo. It is cultivated in various (places 5 Cornwall, Somerfetihirc, &c. M. du Hamel du Mon^eau, of the Boy-al Academy of Sciences at Paris (who wrote a treatife on hulband- ry), gave an account in the year 1749 of an oak which he had kept in water eight years, and which yielded fine leaves every fpring. The tree had, he fays, four or five branches •, the largeft 19 or 20 lines round, and more than 18 inches long. It throve more in the two firft years than it would have done in the heft earth *, it af¬ terwards loft: its vigour, and rather decayed j which he attributed to a defedl in the roots rather than to a want of aliment. (a) Camden informs us of a tradition (which, like moft other traditions of this nature, feems to be founded in ignorance and foftertd by credulity) refpefting an oak near Malwood caftle, where Rufus was killed, viz. that it budded on Chriftmas day, and withered before night. This tree, the fame tradition reports to have been that againft which Tyrrel’s arrow glanced. % OAK f ^07 ] OAK O- Mi d"e Euffon made feme experiments en oak tree&; —» ~mmJ the rehdt of which is recorded in the G-entlcnian’s Magazine, 1754. He had compared barked with un- barked trees, and proves, we think with i'ucctfs, from a variety of trials, that timber barked and dried fland- ing, is always heavier and confiderably ftronger than timber kept in its bark. The baik of oak trees was formerly thought to be extremely ufeful in vegetation. One load (Mr Mills in his Treatife on Hufbandry informs us) of oak bark, laid in a heap and rotted, after the tanners have ufed it for drefhng of leather, will do more fervice to ftilF cold land, and its effects will laft longer, than two loads of the riched dung; but this has been ftrenu- c,Lilly controverted. (See OJK Leaves). Tlie baric, in medicine, is alfo a Huong aftxingent j and hence Hands recommended in haemorrhagies, alt- vine ftuxes, and other pxieternatiucal or immoderate fccretions; and in thefe it is fometknes attended with good effects. Some have alleged, that by the ufe of this bark every purpofe can be anfwered which may be obtained from Peruvian hark. But after 1'everal very fair trials, we have by no means found this to be the cale. Befides the bark, the buds, the acorns and their cups are ufed ; as alfo the galls, which are excrefcences eaufed by infects on the oaks of the eaftem countries,, of which there are divers fonts ; fome pcrfedtly round and fraoothr fome rougher with fmaJl protuberances, but all generally having a round hole in them. All the parts of the oak are Hypfcic,, binding, and ufeful in all kinds of fluxes and bleedings, either inward or outward. The bark is frequently ufed in- gargarifms, for the relaxation of the uvula, and for fore mouths and throats: it is alfo ufed in reftringent clyfters and injedtions, againft the prolapfus uteri or ani. The acorns, beaten to pow¬ der, are frequently taken by the vulgar for pains in the fide. The only officinal preparation is the aqua germinum quereus. Ojk Leaves. The ufe of oak bark in tanning, and in hot-beds, is generally known For the latter of thefe purpofes, however, oak leaves are now found to anfwer equally well, or rather better. In the notes to Dr Hunter’s edition of Evelyn’s Treatife on Foreft Trees, we find the following diredlions for their ufe by W. Speechly : The leaves are to be raked up as foon as pofiible after they fall from the trees. When raked into heaps, they fliould immediately be carried into fome place near the bot-houfes, where they may lie to couch. Mr Speechly fays, it was his cuftom to fence them round with charcoal hurdles, or any thing to keep them from being blown about the garden in windy weather. In this place they tread them Well, and water them in cafe they happen to have been brought in dry. The heap is made fix or feven feet thick, and covered over with old mats, or any thing elfe, to prevent the upper leaves from being blown away. In a few days the heap will come to a ftrong heat. For the firft year or two in which he ufed thefe leaves, our author did not continue them in the heap longer than ten days or a fortnight: but by this method of management they fettle fo much when brought to the hot-hodfe, that a fupply was very foon required; and he afterwards found, that it was proper to let them remain five or fix weeks in the heaps before they ate brought to the hot-knife. In gettino- them into the pine pots, if they appear dry, they are to be watered, and again trodden down exceedingly well, in layers, till the pits are quite full. The whole is then covered with tan bark, to the thicknefs of. two inches, and weh trodden down, till the furtace becomes fmooth ana even. On this the pine pots are to be placed in the manner they are to Hand, beginning with the middle row firft, and filling up. the fpaces between the pots with tan. In this manner we are to proceed to the next row, till the whole be finilhed 'T and this operation is perform¬ ed in the fame manner as when tan only is ufed. The leaves require no farther trouble through the whole fea- fon.j as they, will retain a conftant and regular heat for x 2 months without ftirring or turning 5 and our author irrfoims us, that if he may judge from their appearance when taken out (being always, entire and perfect), it is probable they would continue their heat through a fecond year ; but, as an annual fupply of leaves is eafily obtained, the experiment is hardly worth making. After tliis, the pines will have, no occafion to be moved but at Hated times of their management, viz. at the drifting them in their pots, &c. when at each time a little frefh tan (hould be added to make up the deficiency arifing from the fettling of the beds ; but this will be inconfiderable, as the leaves do not fettle much after their long couching. During the firft two years of our author’s pradhee he did not ufe any tan, but plunged the pine pots into the leaves, and juft covered the fur- face of the beds, when finifhed, with a little faw-duft, to give it a neatnefis. lifts method, however, was attended with one inconvenience ; for, by the caking of the leaves, they flirunk from the fides of the pots* whereby they became expofed to the air, and at the fame time the heat of the beds was permitted to efcape. “ Many powerful reafons (fays Mr Speechly) may¬ be given why oak leaves are preferable to tanners bark. 1. They always heat regularly ; for during the whole time that I have ufed them, which is near feven years, I never once knew of their heating with vio¬ lence ; and this is fo frequently the cafe with tan, that I affirm, and indeed it is well known to every perfon converfant in the management of the hot-houfe, that pines fuffer more from this one circumftanee, than all tne other, accidents put together, infedts excepted.— When this accident happens near the time of their fruiting, the effedl is foon feen in the fruit, which is exceedingly Imall and ill-fhaped. Sometimes there will be little or no fruit at all; therefore gardeners who make ufe of tan only for their pines, fliould he moft particu¬ larly careful to avoid an over-heat at that critfealjundlure —the time of ffiowing the fruit. “ 2. The heat of Dak leaves is conftant ; xvhereas tanner’s bark generally turns cold in a very ffiort time after its furious heat is gone off. This obliges the gar¬ dener to give it frequent turnings in order to promote its heatings. Thefe frequent turnings, not to mention the expence, are attended with the worft confequences * for by the continual moving of the pots backwards and forwards, tile pines are expofed to the extremes of heat and cold, whereby their growth is confiderably retarded; whereas, when leaves are ufed, the pines will have no oecafion to be moved but at the times of ■potting, &c. The pines have one peculiar advantage in this undifturbed fituation ; their roots grow through the bottoms of the pots, and mat among the leaves m a OAK r ios ] OAK Oak. a furpnfing 'manner. From the vigour of the plants —v 1 when in this fituation, it is highly probable that the leaves, even in this Hate, afford them an uncommon and agreeable nourifhment. “ 3. There is a faving in point of expence ; which is no inconfiderable objeft in places where tan cannot be had but from a great diftance. “ 4. The laft ground of preference is, that decayed leaves make good manure j whereas rotten tan is ex¬ perimentally found to be of no value. I have often tried it both on fand and clay, and pn wet and dry land •, and never could difcover in any of my experi¬ ments, that it deferved the name of a manure ; whereas decayed leaves are the richeft, and of all others the moft proper manure for a garden. Leaves mixed with dung make excellent hot-beds; and I find that beds compounded in this manner, preferve their heat much longer than when made entirely with dung-, and in both cafes, the application of leaves will be a confider-- able faving .of dung, which is a circumftance on many accounts agreeable.” OAK-Leaf Galls. Thefe are of feveral kinds *, the remarkable fpecies called the mu/hroom gall is never found on any other vegetable fubftance but thefe leaves: and befide this there are a great number of other kinds. .... The double gall of thefe leaves is very Singular, be- caufe the generality of produftions of this kind affeft only one fide of a leaf or branch, and grow all one way : whereas this kind of gall extends itfelf both ways, and is feen on each fide of the leaf, in form of two protuberances, oppofite the one to the other. I hefe are of differently irregular fhapes, but their natural figure feems that of two cones, with broad bafes, and very obtufe points, though fometimes they are round, or ^ very nearly lo. . . Thefe make their firft appearance on the leal in April, and remain on it till June or longer. They are at firft green, but afterwards yellowilh, and are fofter to the touch than many other of the produftions of this kind: they are ufually about the fize of a large pea, but fometimes they grow to the bignefs of a nut. When opened, they are found to be of that kind which are in¬ habited each by one infeft only, and each contains one cavity. The cavity in this is, however, larger than in any other gall of the fize, or even in many others of three times the fize the fides of it being very little thicker than the fubftance of the leaf. It is not eafy to afcertain the origin of the feveral fpecies of flies which are at times feen in this manner to come out of the fame fpecies of galls. It feems the common courfe of nature, that only one ipecies ol infea forms one kind of gall 5 yet it may be, that two or three kinds may give origin to the fame kind. There is, however, another occafion of our feeing dif¬ ferent fpecies come out of different galls of the fame kind : and this is the effba of the enemies of the pro¬ per inhabitants. It might appear that the parent fly, when (he. had formed a gall for the habitation of her worm offspring, had placed it in an impregnable fortrefs; but this is not the cafe -, for it frequently happens, that a fly, as fmall perhaps as that which gave origin to the gall, produces a worm which is of the carnivorous kind, as the other feeds on vegetable juices. This little fly, well knowing that where there is one of thefe protu¬ berances on a leaf, there is a tender and defencelefs in- fe£t within, pierces the fides of the gall, and depofites her egg within it. This, when it hatches into a worm, feeds upon the proper inhabitant ; and, finally, after devouring it, paffes into the chryfalis ftate, and thence appears in the form of its parent fly, and is feen mak¬ ing its way out of the gall, in the place of the proper inhabitant. On opening thefe leaf-galls, which are properly the habitation only of one animal, it is common to find two, the ftronger preying upon the body of the other, and fucking its juices as it does thofe of the leaf: often it is found w holly employed in devouring its un¬ offending neighbour at once: this is probably the cafe when its time of eating is nearly over: and, in fine, when we find the gall inhabited by only one infedf, *or containing only one chryfalis^ as it ought in its natu¬ ral ftate to do, we are never certain that this is the proper inhabitant, as it may be one of thefe deftroy- ers who has eaten up the other, and fupplied its place. See Aphis, Entomology Index. 0AK Saw-dujl is now found to anfwer the purpofes of tanning, as well, at lead, as the bark. See Tan¬ ning. 0AKofJerufalem. See Chenopodium, Botany Index.- OAKHUM, Ockham, or Oakum, in fea-language, denotes the matter of old ropes untwifted and pulled out into loofe hemp, in order to be uied in caulking the feams, tree nails, and bends of a (hip, for flopping or preventing leaks. OAKHAMPTON, a town of Devonfhire, which fends two members to parliament, has 1430 inhabitants, and a manufafture of ferge j fituated in W. Long. 4. 5. N. Lat. 50. 48. CANNES, a being in Chaldean mythology, repre- fented as half a man and half a fiih. According to Be- rofus and other fabulous writers, this monfter was the ci¬ vilizer of the Chaldeans; to whom he taught a fyftem of jurifprudence fo perfeft as to be incapable of improve¬ ment. In difcharging the duties of his office, he fpent the day on dry land, but retired every night into the ocean or the river. See Mythology, N° 25. O AR, a long piece of timber, flat at one end and round or fquare at the other; and which being applied to the fide of a floating veffel, ferves to make it advance upon the water. That part of the oar which is out of the veffel, and which enters into the water, is called the blade, or wajh-plat; and that wffiich is within board is termed the loom., whofe extremity being fmall enough to be grafped by the rowers, or perfons managing the oars, is called the handle. To pufti the boat or veffel forwards by means of this inftrument, the rowers turn their backs forward, and, dipping the blade of the oar in the water, pull the handle forward fo that the blade at the fame time may move aft in the wTater : but fince the blade cannot be fo moved, without ftriking the water, this impullion is the fame as if the water were to ftrike the blade from the ftern towards the head: the yeffel is therefore necef- farily moved according to this direflion. Hence it fol¬ lows, that {he will advance with the greater rapidity, by as much as the oar ftrikes the water more forcibly. Thus it is evident, that an oar a&s upon the fide of a boat Oak Oar. Oak H Oath. OAT [ 109 ] OAT boat or veflfel like a lever of the fecond clafs, whofe ful¬ crum is the ftation upon which the oar refts on the boat’s gunnel. In large veflels, this ftation is ufually called the row port ; but in lighters and boats it is always term¬ ed the row lock. OARI8TUS, or Oaristys, a term in the Greek poetry, fignifying a dialogue between a hufband and his wife ; fueh as that in the fixth book of the Iliad between Hedtor and Andromache. Scaliger obferves, that the oariftus is not properly any particular little poem, or entire piece of poetry ; but al¬ ways a part of a great one. He adds, that the paflage now cited in Homer is the only proper oariftus extant in the ancient poets. OASIS, the name of a fertile fpot in the midft of a fandy defert. Many of thofe fpots, or oafes, in the African deferts are remarkable for their fertility. OAT. See Avena, Botany Index. Mr Bruce gives the following account of the oats which he found growing wild in Aroofti, a fmall terri¬ tory in Abyflinia, not far from the fource of the Nile : “ Wild oats (fays he) grow up here fpontaneoufly to a prodigious height and fize, capable often of concealing both the horfe and his rider, and fome of the ftalks being little elfe than an inch in circumference. They have, when ripe, the appearance of fmall canes. The inhabitants make no fort of ufe of this grain in any period of its growth : the uppermoft thin hulk of it is beautifully variegated with a changeable purple colour; the tafte is perfeftly good. I often made the meal into cakes in remembrance of Scotland.” Our author in¬ forms us, that the Abyflinians could never be brought to relilh thefe cakes, which they faid were bitter, burnt their ftomachs, and made them thirfty. He is, however, decidedly of opinion, that the wdld oat of Aroofti is the oat in its original ftate ; and that it has degenerated everywhere in Europe. OATH, an affirmation or promife, accompanied with an invocation of God to witnefs what we fay; and with an imprecation of his vengeance, ora renunciation of his favour, if what sve affirm be falfe, or what we promife be not performed (a). The laws of all civilized itates have required the fecurity of an oath for evidence given in a court of juf- tice, and on other occafions of high importance (b) ; and the Chriftian religion utterly prohibits fwearing, except when oaths are required by legal authority. Indeed no ferious and reflefting theift, whether he ad¬ mit the truth of revelation or not, can look upon fwearing on trivial occafions as any thing elfe than a fin of a very heinous nature. To call upon that in¬ finite and omniprefent Being, who created and fuf- tains the univcrfe, to witnefs all the impertinence of idle converfation, of which great part is commonly ut¬ tered at random, betrays a fpirit fo profane, that nothing ftiort of experience could make us believe it poffible for a creature endowed with reafon and refle61ion to be ha¬ bitually guilty of a praflice fo impious. No man can plead in extenuation of this crime, that he is tempted to fwear by the importunity of any appetite or paffion im¬ planted in the human breaft: for the utterance of a profane oath communicates no pleafure and removes no uneafinefs : it neither elevates the fpeaker nor depreffes the hearer. Quakers and Moravians, fwayed by thefe confidera- tions, and by the fenfe which they put upon certain texts of Scripture, refufe to fwear upon any occafion, even at the requifition of a magiftrate, and in a court of juftice. Thefe fcruples are groundlefs; and feem to proceed from an incapacity to diftinguifti between the proper ufe and abufe of fwearing. It is unque- ftionably impious to call upon God to witnefs imper¬ tinences, or to ufe his tremendous name as a mere ex¬ pletive in converfation ; but it by no means follows, that we may not pioufly call upon him to witnels truths of importance, or invoke his name with reve¬ rence and folemnity. No individual could, without grofs profanenefs, pray for a thoufand times more wealth than he may ever have occafion to ufe ; but it was never thought profane to pray “ day by day for our daily bread, for rain from heaven, and fruitful fea- fons.” If it be lawful to alk of God thefe earthly bleffings, becaufe he alone can beftow them; it cannot furely be unlawful, where the lives or properties of our Oath. (a) The word oath is a corruption of the Saxon eoth. It is often in England called a corporal oath, becaule, in the days of popery, ,the perfon was fworn over the hoft or corpus Chrifti. (b) l he various oaths required by different nations at different times, and the various forms, &c. of impofing them, is a fubjeft of very confiderable extent and curiofity : An account of them does not fall within the plan of the prefent article ; it would indeed extend it to an undue length ; we cannot, however, omit obferving, what is doubtlefs very remarkable, that the grand impoftor Mahomet taught the Modems, that their oaths might be diffol- ved. I his wonderful dodftrine is contained in the 66th chapter of the Koran ; which, to free himfelf from his promife and oath to Hafsa his fpoufe, he pretended was revealed. What the ufe of oaths is in fuch circumftances, or Avhat fecurity they afford for performance, it is difficult to afcertain. It is alfo very remarkable, that an oath refpedling marriages was the caufe of the firft divorce at Rome. The circumftance happened about the year of the city 52^, Pofthumius Albinus and Spurius Carvilius being confuls. 1 he cenfors of this year obferving the population declining, and imagining it proceeded from interefted marriages and promifcuous cohabitation, obliged all the citizens to fwear, that they wrould not marry wdth any other view1 than that of peopling the republic. It raifed, however, many fcruples, and occafioned many domeftic ruptures. Among the reft, one Carvilius Ruga, a man of difthnftion, imagined that he was bound by his oath to divorce his wife, whom he paffionately loved, becaufe fhe was barren, which was the firft inftance of a divorce at Rome from its foundation, though the marriage laws of the kings allowed it; it afterwards, hoAvever, became fhamefully fre¬ quent. T his is alfo a ftriking inftance of the great attention paid to oaths among the Romans ; it is remarked in¬ deed by all writers, that they paid a moft profound refpedl to them; and on that we know they founded their hopes of fuccefs in Avar. O A T i h Cfath. our neighbours, or the fecurity of government is con- 1J' v cerned, to invoke him with reverence to witnefs the truth of our affertions, or the fincerity of our intentions ; becaufe of our truth in many cafes, and of our iincerity in all, none but he can be the witnefe. The text of Scripture upon which the Quakers chiefly reft their argument for the unlawfulnels of all {wearing under the gofpel, is our Saviour’s prohibi- - tion (Mat. v. 34.) : “ I fay unto you, fwear not at all.” But whoever lhall take the trouble of turning over his Bible, and looking at the context, will perceive, that it is only in ordinary converfation, and by no means in courts of juftice, that our Lord prohibits his followr- ers from {wearing at all. There is no evidence what¬ ever, that fwearing by heaven, by the earth, by Jerufa- lem, or by their own heads, was the form of a judicial oath in ufe among the Jews. On the contrary, we are w See Whit- told by Maimonides *, that “ if any man fwear by hea- by on the ven or by earth, yet this is not an oath j” which fure- *iaee- ly he could not have faid, had fuch been the forms of judicial fwearing. Indeed they could not have ad¬ mitted fuch forms into their courts without exprefsly violating the law of Mofes, who commands them to “ Fear the Lord (Jehovah) their God, to ferve him, and to fwear by his NAME.” But the JewTs, as every one knows, had fuch a reverence for the name Jeho¬ vah, that they would not pronounce it on flight occa- lions, and therefore could not fwear by that name in common converfation. Hence, to gratify their pro- penftty to eommon fwearing, they invented fuch oaths as, by heaven, by earth, by Jerufalem, by the life of thy head, &c. and by this contrivance they thought to avoid the guilt of profaning the name Jehovah. Thefe, however, being appeals to infenfible objefts, either had no meaning, or were in faft, as our Sa- ^viour juftly argues, oaths by that God whofe crea¬ tures they were ; fo that the Jew who fwore them was ftill guilty of profanenefs towards the very Jeho- VAH whofe name his fuperftition would not permit him to pronounce. But what puts it beyond all doubt that the ufe of judicial oaths is not wholly prohibited in the gofpel, is the conduct of our Saviour himfelf as well as of his apoftle St Paul. When Jefus was Amply afked by the high prieft, what it was which certain falfe witnefles teftified againft him ? we are told by the evangelifts, that “ he held his peace :” but being adjured by the living God to declare whe¬ ther he was the Chrift, the Son of God, or not, he immediately anfwered the high prieft, without objefting to the oath (for fuch it was) upon, which he was ex- f Palejs amined. “ St Paul, in his Epiftle to the Romansf, Moral Phi- favs,. ‘ God is my vaitnefs, that, without ceafing, I make Ifophy. mention of you in my prayers j and to the Corinthians, ftill more ftrongly, ‘ I call God for a record upon my foul, that, to fpare you, I came not as yet to Corinth.' Both thefe expreflions are of the nature of oaths 5 and the author of the Epiftle to the Hebrews fpeaks of the cuftom of fwearing judicially without any mark of cen- fure or difapprobation : ‘ Men verily fwear by the great¬ er ; and an oath, for confirmation, is to them an end of all ftrife.” But though a nation has an undoubted right to re¬ quire the fecurity of an oath upon occafions of real im¬ portance, we do not hefitate to fay, that, in our opinion, it is fomething worfe than bad policy to multiply oaths, o J 0 A T and to hold out to the people temptations to perjure' Oatk themielves. The fecurity which an oath affords, de-—v—u pends entirely upon the reverence which attaches to it in the mind of- him by whom it is given j but that re¬ verence is much weakened by the frequency of oaths, and by the carelefs manner in which they are too often adminiftered. An excellent moralift J oblerves, with { Mr Pa- truth, that “ the levity and frequency with which oaths. are adminiftered, has brought about a general inadver¬ tency to the obligation of them, which both in a re¬ ligious and political view is much to be lamented j and it merits (continues he) public confideration, whether the requiring of oaths on fo many frivolous oceafions, efpecially in the cuftoms, and in the qualification for petty offices, has any other effedl than to make them cheap in the minds of the people. A pound of tea can¬ not travel regularly from the Ihip to the confumer with¬ out coiling half a doszen oaths at leaft ; and the fame fe¬ curity for the due difeharge of his office, namely that of an oath, is required from a church warden and an arch- bfhop, from a petty confable and the chief juJUce of England. Let the law continue its owm functions, if they be thought requifite ; but let it fpare the folemni- ty of an oath: and where it is neceflary, from the want of fomething better to depend upon, to accept a man’s own word or own account, let it annex to prevarication penalties proportioned to the public confequence of the offence.” That thefe pernicious confequences of frequent oaths are not felt only in England, we have the evidence of another refpeftable writer, whofe acutenefs well quali¬ fied him to obferve, whilft his ftation in fociety furuiffi- ed him with the beft opportunities of obferving, the ef¬ fects of repeated fwearing upon the morals of Scotch¬ men. “ Cuftomhoufe oaths (fays Lord Karnes j) have § Sketches become fo familiar among us, as to be fwallowed with- of the Hi/- out a wry face; and is it certain that bribery and per- tory °f jury in ele&ing parliament members are not approach- ing to the fame cool ftate ? men creep on to vice by degrees. Perjury, in order to fupport a friend, has be¬ come cuftonaary of late years ; witnefs fi&itious quali¬ fications in the eleftors of parliament-men, which are made effeftual by perjury : yet fuch is the degeneracy of the prefent times, that no man is the worfe thought of upon that account. We nraft not flatter ourfelves, that the poifon will reach no farther : a man who bog¬ gles not at perjury to ferve a friend, will in time be¬ come fuch an adept, as to commit perjury in order to ruin a friend when he becomes an enemy.” Befides the frequency of oaths, we have mentioned the irreverent manner in which they are too often ad¬ miniftered as one of the caufes which make them cheap in the eftimation of the people. In this view, the form of the oath, and the ceremonies with which it is required to be taken, are of confiderable importance. “ The forms of oaths in Chriftian countries (fays Mr Paley) are very different j but in none I believe Avorfe contrived either to convey the meaning or to imprefe the obligation of an oath, than in England. In that country the juror, after repeating the promife or affirma¬ tion which the oath is intended to confirm, adds,. ‘ fo help me God or more frequently the fubftance of the oath is repeated to the juror by the officer or magiftrate who adminifters it j adding in the conclufion, ‘ fo help you God.’ The energy of the fentence refides in thq particle O A T [ Oath, particle fo ; fo, i. e. hac lege, ‘ upon condition of my —' fpeaking the truth, or performing thispromife, may God kelp me, and not other wife.’ The juror, whilft he hears or repeats the words of the oath, holds his right hand upon a Bible, or other book containing the four gofpels. The conclufion of the oath fometimes runs, ‘ ita me Deus ad]uvet, et lute faridla evangelia f or ‘ fo help me God, and the contents of this book which lafl daufe forms a connexion between the words and a&ion of the juror, which before was wanting. The juror then kifles the book.” This obfeure and elliptical form, the excellent au¬ thor juftly obferves, is ill calculated to imprefs the juror with reverence : and he feems to think great preference due to the form of judicial oaths in Scot¬ land. In that country the juror holds up his right hand towards heaven, and fw.ears by Almighty God, and as he lhall anfwer to God at the great day of judgment, “ that he will tell the truth, the whole truth, and nothing but the truth, fo far as he knows, or it ihall be aiked of him.” This, if adminiftered with dignity and reverence, is an oath fuffieiently folemn and well calculated to have the proper effect upon the mind of the juror, as it brings immediately into his view the Author of his beings and the awful day of final retribution when every man (hall receive the tilings done in his body according to that he hath done, whe¬ ther it be good or evil. But when the magiftrate, as isptoo often the cafe, repeats this folemn invocation without thing from his feat at the name of the Su¬ preme Being, and in a tone of carelelfnefs which may convey to the ignorant juror an opinion that he lias himfelf no fexious belief that there ever will be a great day of judgment, the form, however excellent, .makes not its full imprefiion. But let us fuppofe the oath to be adminiflered with the .greateft dignity and reverence, the words of the promife itfelf appear to us by no means unexception¬ able. In a trial on life and death, we fliould be glad to know what this oath binds the witnefs to declare. Is he^ to tell all that he knows touching the matter in quell ion or only all that (hall be ajked of him ? If he be obliged, in virtue .of his oath, to tell ail that he jvnxws, the claufe—“ or it fhall be afked of you” is taperfluous, and calculated to miflead. If he be bound to tell nothing more ,of the truth than what (hall be .dked of him, tke word or Ikould be changed into and; he fiiould fwear “ to tell the truth, &c. fo far as he knows, and it {hall be ajked of him.” The court, we believe, confiders the witnefs as bound to declare every thing which he knows .touching the .matter in queilion. The greater part of witnelfes, on the-other band, con- fider themfelves as bound no farther by their oath than to give true anfwers to fuch queftions as {hall be aiked of them. I hey would do well, however, to remember that as oaths are defigned for the fecurity of the public, they muft be interpreted in the fenfe in which the pu- bnc intends them, other,wife they afford no fecurity. .out the fenfe of tlm r>ivhlio tc lour • j i. _ But tue fenfe of the public is the law ; and as it be¬ longs to the court to declare what the mind of the law is, the witnefs, who has any doubt concerning the extent ol the obligation impofed on him by the words of this oath, fhould apply to the court for a folution of that doubt, which will be a fafe guide to him refpedting the evidence which he is to give. Should the court, in re- 5 m ] GAT' folving the doubts of a witnefs, give an opinion concern- Oath, ing the fenfe of any other part of the oath contrary to —y'—“ What he apprehends to be the defign of the law in im- pofing it, he is bound to difregard filch opinion ; becaufe it h only where he himfelf is doubtful that the court has a right to interfere, and becaufe in all moral queftions men muft be finally determined by their own judgment and conference. There is one cafe, and but one, in which, whatever fenfe be put upon the words of the oath, no witnefs is obliged to declare the whole truth. It is when fuch declaration would tend to accufe himfelf of fome legal crime 5 for as-the laws of Scotland and England con- ftrain no man to become his own accufer, they muft be confidered as impofing the oath of teftimony with this tacit refervation. “ The exception, however *, * Paley's muft be confined to legal crimes. A point of honour, Moral Phi* of delicacy, or of reputation, may make a witnefs back- lof°l>hX' ward to difclofe fome circumftance with which he is acquainted j but is no excufe for concealment;, unlels it could be fhown, that the law which impofes the oath, intended to allow this indulgence to fuch mo¬ tives. The exception is alfo withdrawn by compact between the magiftrate and the witnefs, when an ac¬ complice is admitted to give evidence agaiaft the part¬ ners of his crime.” But thefe are a fort of witnelfes to . whom a fenfible jury will always liften with a very - cautious ear. Oaths are either affertory or promiffbrij. Afiertory* oaths are required both to confirm our veracity in evidence, and to give fecurity to the public that we believe certain propofitioms conceived to be of public importance. An oath in evidence binds the juror to declare what he knows to be true, and nothing bus what he knows to be true. An oatli required to af» fare the .public of our belief in the truth of any propo¬ rtion, cannot, without the guilt of perjury, be taken by any man, who, at the time of fwearing, has the flighteft doubt whether the propofition be really true. Such an oath, however, though it unqueftionably re¬ quires the fincerity of the juror’s belief at the time when it .is given, cannot oblige him to continue in that belief as long as he may live ; for belief , is not in any man’s power : it is the ncceffary conlequence of evi¬ dence, which compels the affent of the mind according as it appears to preponderate on the. one fide or on the other. No man, therefore, can be juftly accufed of perjury for holding opinions contrary to thofe which he may formerly have fwqm to believe ; becaufe his belief at the time of emitting his oath may have been the neceffary refiilt of the evidence which then ap~- peared befoie him j and his change of opinion may have reiulted with the lame nectllity from fuperior evidence which had been fince thrown into the oppofite Icale, and made it preponderate. On this account, we cannot help thinking, that all affertory oaths, except fuch as are neceffary to confirm teftimony refpe&ing- faBs, ought either to be aboliflied or expreffed with great uaution. Of truths intuitively certain or capable of rigid demonftration, no man of common fenfe can en¬ tertain a doubt 3 and therefore the public never requires from individuals the folemnity of an oath as an affurance of their believing fuch truths. But with refpeft to the truth of propofitions which admit of nothing fupe¬ rior to moral evidence on either fide, a man of the moil ftgady ' O B E [I! Oath fleady virtue may think differently at different periods II of his life •, and in fuch cafes, the effedt of an oath, if Edom" ^ have any effedt, can only be either, to fhut the man’s eyes againlt the light, or to make his integrity be caufe- lefsly queftioned by thofe who (hall obferve his change of belief. Promiffory oaths cannot, without the guilt of pcrju- ty, be given by him, who, at the time of fwearing, knows that it will not be in his power to fulfil the pro- mife, or who does not ferioufly intend to fulfil it. A romiffory oath cannot, without great guilt, be given y any man, who at the time of fwearing believes the objedt of the promife to be in itfelf unlawful j for if he ferioufly mean to fulfil his oath, he calls upon Almighty God to witnefs his intention to commit a crime. Pro- miffory oaths give to the public greater fecurity than a fimple promife; becaufe the juror having the thoughts of God and of religion more upon his mind at the one time than at the other, offends with a higher hand, and in more open contempt of the divine power, knowledge, and juftice, when he violates an oath, than when he breaks a promife. Yet it is certain that promiffory oaths, though more folemn and facred, cannot be binding, when the promife without an oath would not be fo in an inferior degree ; for the feveral cafes of which, fee Promise and Allegiance. Coronation OATH. See King. OATH LAW, the name of a parifh in Angus, about two miles from Forfar, chiefly remarkable for the remains of a Roman camp called Battle-dykes (vul¬ garly Black-dykes'), which is about a mile wreft of the church. OB ADI AH, or the Prophecy of Obadiah, a cano¬ nical book of the Old Teftament, which is contained in one Angle chapter •, and is partly an invedlive againfl the cruelty of the Edomites, who mocked and derided the children of Ifrael as they paffed into captivity *, and with other enemies, their confederates, invaded and op- preffed thofe ftrangers, and divided the fpoil amongft themfelves } and partly a predidlion of the deliverance of Ifrael, and of the vidlory and triumph of the whole church over her enemies. Obadiah, the prophet, is believed to have been the fame with the governor of Ahab’s houfe, mentioned in the firft book of Kings, (xviii. 3, &c.) who hid and fed the hundred prophets whom Jezebel would have deftroy- -ed; and fome fay, that he w7as that Obadiah whom Jofiah made overfeer of the works of the temple, (2 Chron. xxxiv. 12.). The truth is, that when he lived or prophefied is wholly uncertain : though moft writers make him cotemporary with Hofea, Amos, and Jodi. Obadiah, a valiant man of David’s army, who came to join him in the wildnernefs, with feveral others of the tribe of Gad, (1 Chron. xii. 9.). This was alfo the name of one of thofe whom King Jehofhaphat fent into the cities of Judah to inftruft the people in their religion, (2 Chron. xvii. 7.). It wras al¬ fo the name of one of the principal men of Judah, who figned the covenant that Nehemiah renewed with the Lord, (Nehem. x. 5.). OBED-EDOM, fon of Jeduthun, a Levite, (1 Chr. xvi. 38.) and father of Shemaiah, Jehozabad, Joah, Bacar, Nathaneel, Ammiel, Iffachar, and Peulthai. He had a numerous family, fays the Scripture, (1 Chron, 2 ] QBE xxvi. 4.) becaufe the Lord blelfed him ; and this is the Obed- occaflon of the blefling. When David transferred the ark of the covenant to the city of Jerufalem, Uzzah ha- . ' ving ralhly laid hands on the ark, which he thought to be in danger of falling, was fmitten of God, and died upon the ipot. David terrified at this accident, durft not remove the ark into the place he had provided for it in his own houfe, but fet it up in the houfe of Obtd- edom, which was near the place where Uzzah had been ft ruck dead. But the prefence of the ark not only cre¬ ated no temporal misfortune to the family of this Levite* but, on the contrary, the Lord heaped upon him all forts of bleflings*, which encouraged David fome months after to remove it to the place he had appointed for it. Afterwards Obed-edom and his fons were afligned to be keepers of the doors of the temple, (1 Chron xv. 18, 21.). In the fecond book of Samuel, (vi. 10.) Obed- edom is called the Gittite, probably becaufe he was of Gathrimmon, a city of the Levites beyond Jordan, (Jofh. xxi. 24, 25.). OBELISK, in Architecture, a truncated, quadran¬ gular, and {lender pyramid, raifed as an ornament, and frequently charged either with infcriptions or hierogly¬ phics, Obelifks appear to be of very great antiquity, and to have been firft raifed to tranfmit to pofterity precepts of philofophy, which were cut in hieroglyphical charac¬ ters : aftenvards they were ufed to immortalize the <*reat adfions of heroes, and the memory of perfons be¬ loved. The firft obeliik mentioned in hiftory was that of Ramafes kind of Egypt, in the time of the Trojan war, w'hich was 40 cubits high. Phius, another king of Egypt, raifed one of 55 cubits-, and Ptolemy Phila- delphus, another of 88 cubits, in memory of Arfinoe. Augufttis erefted one at Rome in the Campus Martius, which ferved to mark the hours on a horizontal dial, drawn on the pavement. They Were called by the E- gyptian priefts the fingers of the fun, becaufe they were made in Egypt alfo to ferve as ftyles or gnomons to mark the hours on the ground. The Arabs ftill call them Pharaoh's needles ; whence the Italians call them aguglia, and the French aiguilles. The famous obelilks called the devil's arrows, now reduced to three, the fourth having been taken down in the laft century, ftand about half a mile from the town of Borough-Bridge to the fouth-weft, in three fields, feparated by a lane, 200 feet afunder nearly, on high ground floping every way. Mr Drake urges many arguments for their Roman antiquity, and plainly proves them to be natural and brought from Plumpton quar¬ ries about five miles off, or from Ickly 16 miles off. The crofs in the town, 12 feet high, is of the fame kind of ft one. The eaftermoft or higheft is 22 feet and a half high by 4 broad, and 14^ in girth the fe¬ cond 21-g- by 55-j ; the third 164- by 84. Stukeley’s meafures differ. 1 he flutings are cut in the ftone but not through : the talleft ftands alone, and leans to the fouth. Plot and Stukeley affirm them to be Britifti mo¬ numents, originally hewn fquare. Dr Gale fuppofed that they were Mercuries, which have loft their heads and infcriptions; but in a MS. note in his Antoninus, he acknowledges that he was mifinformed, and that there was no cavity to receive a buft. On the north fide of Penrith, in the churchyard, are two fquare obelilks, of a Angle ftone each, 11 or 12 feet high, 0. B L [ I Obelilk lilgli, about 12 inches diameter, and 12 by 8 at the !l _ Tides, the higheft about 18 inches diameter, with fome- Oblati. a tranfverfe piece to each, and mortifed into round bafe. They are 14 feet afunder, and between them is a grave enclofed between four femicircular ftones of the unequal lengths of five, fix, and four and a half, and two feet high, having on the outfides rude carving, and the tops notched. This is called the Giant'’s grave, and afcribed to Sir Ewan Caefarius, who is faid to have been as tall as one of the columns, and capable of ftretching his arms from one to the other $ to have de* ftroyed robbers and wild boars in Englewood foreft ; and to have had a hermitage hereabouts called Sir Hugh's parlour; but the conje&ures refpedting them are extremely various and contradiftory. A little to the \yeft of thefe is a ftone called the Giant's Thumb, fix feet high, 14 inches at the bafe contra£led to 10, which is no more than a rude crofs, fuch as is at Long- town in Cumberland, and elfewhere j the circle of the crofs 18 inches diameter. Near the town of Forres in the north of Scotland there is a very fine obelilk, 22 feet in height, known by the name of the Forres pillar, or Sweno'sJlone. See Forres. M. Pouchard, in the memoirs of the Academy of In- fcriptions, gives a curious account of fome celebrated Egyptian obelilks. See Gentleman’s Magazine for June 1748. OBJECT, in Philofophy, fomething apprehended or prefented to the mind by fenfation or imagination. See Metaphysics, Part I. Chap. I. Seft. II. OBJECT-Glafs of a Te/efcope, or Microfcope, the glafs placed at the end of the tube which is next the objedt. See Optics and Microscope. OBJECTION, fomething urged to overthrow a po- fition, or a difficulty raifed againft an allegation or pro- pofition of a perfon we are difputing with. OBJECTIVE, is ufed in the fchools, in fpeaking of a thing which exifts no otherwife than as an objedt known. The exiltence of fuch a thing is faid to be ob- jedtive. OBIT, (Lat.) fignifies a funeral folemnity, or office for the dead, moll commonly performed when the corpfe lies in the church uninterred : Alfo the anniverfary of¬ fice, (2 Cro. 51 Dyer 313.). The anniverfary of any perfori’s death was called the obit and to obferve fuch day with prayers and alms, or other commemoration, was the keeping of the obit. In religious houfes they had a regifter, wherein they entered the obits or obitual days of their founders and benefadtors j which was thence termed the obituary. The tenure of obit or chantry lands is taken away and extindt by I Edw. VI. c. 14. and 15 Car. II. c. 9. OBLATE, flattened or ffiortened j as an oblate fphe- roid, having its axis Ihorter than its middle diameter j being formed by the rotation of an ellipfe about the (hofter axis. The earth, whofe polar diameter is Ihort¬ er than the equatorial, is an oblate fpheroid. OBLATI, in church hiltory, were fecular perfons, who devoted themfelves and their eftates to fome mo- naftery, into which they were admitted as a kind of lay brothers. The form of their admilfion was putting the bell ropes of the church round their necks, as a mark or fervitude. They wore a religious habit, but differ¬ ent from that of the monks. Vol. XV. Part I. 13 ] O B O OBLIGATION, in general, denotes any adt where* Obligatlbn by a perfon becomes bound to another to do fome- II thing j as to pay a fum of money, be furety, or the , Qboth> , like. ’ Obligations are of three kinds, viz. natural, civil, and mixed. Natural obligations are entirely founded on natural equity ; civil obligations on civil authority alone, without any foundation in natural equity $ and mixed obligations are thofe which, being founded on natural equity, are farther enforced by civil authority. In a legal fenfe, obligation fignifies a bond, wherein i? contained a penalty, with a condition annexed, for the payment of money, &c. The difference betiveen it and a bill is, that the latter is generally without a penalty or condition, though it may be made obliga¬ tory : and obligations are fometimes by matter of re¬ cord, as ftatutes and recognizances. See the article Bond. Moral Obligation. See Moral Philosophy, N° 58, &e. OBLIQUE, in Geometry, fomething allant, or that deviates from the perpendicular. Thus an oblique angle is either an acute or obtufe one, i. e. any angle except 4 a right one. OBLIQUE Cafes, in Grammar, are all the cafes ex¬ cept the nominative.. See Grammar. OBLIQUE Afcenfon, is that point of the equinoctial which rifes with the centre of the fun, or liar, or any other point of the heavens, in an oblique fphere. OBLIQUE Circle, in the llereographic projection, is any circle that is oblique to the plane of projection. OBLIQUE Defcenfon, that point of the equinoCtial which fets with the centre of the fun, or liar, or any other point of the heavens, in an oblique fphere. OBLIQUE Line, that which, falling on another line, makes oblique angles with it, viz. one acute, and the other obtufe. OBLIQUE Planes, in Dialling, are thofe which de¬ cline from the zenith, or incline towards the horizon. See Dial. OBLIQUE Sailing, in Navigation, is when a Ihip fails upon fome rhumb between the four cardinal points, making an oblique angle with the meridian ; in which cafe Ihe continually changes both latitude and longitude. See Navigation, Chap. VIII. OBLIQUUS, in Anatomy, a name given to feveral mufcles, particularly in the head, eyes, and abdomen. See Anatomy, Table of the Miifcles. OBLONG, in general, denotes a figure that is long¬ er than broad ; fuch is a parallelogram. OBOLARIA, a genus of plants belonging to the didynamia clafs 5 and in the natural method ranking under the 40th order, Perfon atm. See Botany Index. OBOL US, an ancient filver money of Athens, the fixth part of a drachma j worth fomewhat more than a penny farthing fterling.—The word comes from the Greek or “ fpit, or broach 5” either be- caufe it bore fuch an impreffion j or becaufe, according to Euftathius, it was in form thereof. But thofe now in the cabinets of the antiquaries are round. Obolus, in Medicine, is ufed for a weight of ten grains, or half a fcruple. OBOTH, an encampment of the Hebrews in the wildernefs. From Punon they went to Oboth, and from Oboth to Ije-abarim, {Numb. xxi. 10. xxxiii. 43). P Ptolemy Oboth O B S -[ii Ptolemy fpeaks of a city called Oboda, or Eboda, in Arabia Petrrea, which is the fame as Oboth. Pliny and the geographer Stephanus mention it alfo. Stepha¬ nas makes it belong to the Nabathaeans, and Pliny to the Helmodeans, a people of Arabia. It was at Oboth that they Avorfhipped the god Obodus, which lertul- lian joins with Dufares, another god or king of this country. OBREPTITlOUS, an appellation given to letters patent, or other inftruments, obtained of a fuperior by furprife, or by concealing from him the truth. OBSCURE, fomething that is dark and refle&s lit¬ tle light in material objects, or that is not clear and in¬ telligible in the objects of the intelledl. OBSECRATION, in Rhetoric, a figure whereby the orator implores the affiftance of God or man. OBSEQUIES, the fame with funeral folemnities. See Funeral. OBSERVATION, among navigators, fignifies the taking the fun’s or the liars meridian altitude, in order thereby to find the latitude. OBSERVATORY, a place deftined for obferving the heavenly bodies; being generally a building erett- ed on fome eminence, covered with a terrace for making alironomical obfervations. The more celebrated obfervatories are, I. The Green¬ wich obfervatory, built in 1676, by order of Charles II. at the folicitation of Sir Jonas Moore and Sir Chrifto- pher Wren j and furnilhed with the moll accurate in- Rruments ^ particularly a noble fextant of feven feet ra¬ dius, with telefcopic fights. 2. The Paris obfervatory, built by the order of Louis XIV. in the fauxbourg St Jacques. It is a very fingular, and a very magnificent building, the defign of Monfieur Perault: it is 80 feet high ; and has a terrace at the top. The difference in longitude between this and the Greenwich obfervatory is 2° 2o'. In it is a cave or cellar, of 170 feet defcent, for ex¬ periments that are to be made far from the fun, &c. particularly fuch as relate to congelations, refrigerations, indurations, confervations, &c. 3. Tycho Brahe’s obfervatory, which was in the little iiland Ween, or Scarlet I Hand, between the coails of Schonen and Zealand in the Baltic. It Avas ere&ed and furnifhed Avith inftruments at his oAvn expence, and call¬ ed by him Uraniburg. Here he fpent twenty years in obferving the ftars •, the refult is his catalogue. 4. Pekin obfervatory. Father Le Compte defcribes a very magnificent obfervatory, erected and furniflied by the late emperor of China, in his capital, at the in- terceffion of fome Jefuit miffionaries, principally Father Verbeift, Avhom he made his chief obferver. The in¬ ftruments are exceedingly large but the divifion lefs accurate, and the contrivance in fome refpedls lefs com¬ modious, than that of the Europeans. The chief are, An armillary zodiacal fphere of fix feet diameter ; an equinoctial fphere of fix feet diameter •, an azimuthal ho¬ rizon of fix feet diameter ; a large quadrant fix feet ra¬ dius ; a fextant eight feet radius *, and a celeftial globe fix feet diameter. Obfervatories, as they are very ufeful, and indeed ab» folutely neceflary for aftronomers, fo they have become far more common than they w’ere. There is a very ex¬ cellent one now at Oxford, built by the Uuftees of Dr. 4 ] O B S Radcliffe, at the expence of nearly 30,000!. At Cam- Obffivj, bridge there is as yet no public obfervatory. Over the . 1 great gate of Trinity college, indeed, there is one which is called Sir IJaac Newton's, becaufe this great philofopher had ufed it *, but it is gone to decay. It Avere Avell if the univerfity Avould repair and preferve it in memory of that truly great man. In St John’s, too, there is a fmall one. The late ingenious Mr Cotes had ufed to give le&ures in Sir Ifaac Newton’s on experi¬ mental philofophy. In Scotland there is an obfervatory at Glafgow belonging to the univerfity : there is one erefted on the Calton hill at Edinburgh •, but it is in very bad repair, (fee Edinburgh) } and there is an ex¬ cellent one at Dublin. 3. Bramins obfervatory at Benares. Of this Sir Ro- Plate bert Barker gives the folloAving account, (Phil. Tranf. CCCLXX. vol. Ixvii. p. 598.). “ Benares in the Eaft Indies, one of the principal feminaries of the Bramins or priefts of the original Gentoos of Hindoftan, continues ftill to be the place of refort of that feft of people j and there are many public charities, hofpitals, and pagodas, Avhere fome thoufands of them iioav refide. Having frequently heard that the ancient Bramins had a knoAvledge of aftronomy, and being confirmed in this by their infor¬ mation of an approaching eclipfe both of the fun and moon, I made inquiry, when at that place in the year 1772, among the principal Bramins, to endeavour to get fome information relative to the manner in Avhich they Avere acquainted Avith an approaching eclipfe. The moft intelligent that I could meet with, hoAvever, gave me but little fatisfadion. I was told that thefe mat¬ ters were confined to a few, Avho Avere in poffeflion of certain books and records ; fome containing the myfte- ries of their religion ; and others the tables of aftrono- mical obfervations, Avritten in the Shanfcrit language, Avhich few underftood but themfelves : that they Avould take me to a place Avhich had been conftrufted for the purpofe of making fuch obfervations as I Avas inquiring after, and from avhence they fuppofed the learned Bra¬ mins made theirs. I Avas then conduded to an ancient building of ftone, the lower part of which, in its pre-> fent fituation, Avas converted into a liable for horfes, and a receptacle for lumber; but by the number of court-yards and apartments^, it appeared that it mull once have been an edifice for the ufe of fome public bo¬ dy of people. Me entered this building, and Avent up a ft air cafe to the top of a part of it, near to the river Ganges, that led to a large terrace, Avhere, to my fur¬ prife and fatisfadion, I faw a number of inftruments yet remaining, in the greateft prefervation, ftupendoutly large, immoveable from the fpot, and built of ftone, fome of them being upwards of 20 feet in height} and although they are faid to have been, ereded 200 years- ago, the graduations and divifions on the feveral arcs appeared as well cut, and as accurately divided, as ifi they had been the performance of a modern artift. T he. execution in the conftrudion of thefe inftruments exhi¬ bited a mathematical exadnefs ifl the fixing, bearing, fitting of the feveral parts, in theneceffary and fufficient fupports to the very large ftones that compofed them, and in the joining and faftening each into the other by means of lead and iron. “ The fituation of the tAVO large quadrants of the inftrument marked A in the plate, Avhofe radius is nine feet tAVO inches, by their being at right angles with a gnomon. O B S c Qbfem- gnomon at twenty-five degrees elevation, are thrown toiy. ;nt;0 fm-h ail oblique fituationas to render them themoft v ~ difficult, not only to conftrudi of fuch a magnitude, but to fecure in their pofition for fo long a period, and af¬ fords a ftriking inftance of the ability of the architect in their conftru£tion : for by the Ihadow of the gnomon thrown on the quadrants, they do not appear to have al¬ tered in the lead from their original pofition ; and fo true is the line of the gnomon, that, by applying the eye to a fmall iron ring of an inch diameter at one end, the fight is carried through three others of the fame di- menfion, to the extremity at the other end, diftant 38 feet 8 inches, without obllrudlion $ fuch is the firmnefs and art with which this inftrument has been executed. This performance is the more wonderful and extraordi¬ nary, when compared with the works of the artificers of Hindoftan at this day, who are not under the immediate dire&ion of an European mechanic ; but arts appear to have declined equally with fcience in the call. “ Lieutenant Colonel Archibald Campbell, at that time chief engineer in the Lad India Company’s fervice at Bengal, made a perfpeclive drawing of the whole of the apparatus that could be brought within his eye at one view ; but I lament he could not reprefent fome Very large quadrants, whofe radii were about 20 feet, they being on the fide from whence he took his draw¬ ing. Their defeription, however, is, that they are ex- aft quarters of circles of different radii, the larged: of which I judged to be 20 feet, condrufted very exaftly on the fides of done walls, built perpendicular, and fi- tuated, I fuppofe, in the meridian of the place : a brafs pin is fixed at the centre or angle of the quadrant, from whence, the Bramin informed me, they dretched a wire to the circumference when an obfervation wras to be made *, from which, it occurred to me, the obferver mud have moved his eye up or down the circumference, by means of a ladder or feme fuch contrivance, to raife and lower himfelf, until he had difeovered the altitude of any of the heavenly bodies in their paffage over the meridian, fo expreffed on the arcs of thefe quadrants : tbefe arcs were very exaftly divided into nine large fec- tions ; each of which again into ten, making ninety lef- fer divifions or degrees •, and thofe alfo into twenty, ex- preffing three minutes each, of about two-tenths of an inch afunder ; fo that it is probable they had fome me¬ thod of dividing even thefe into more minute divifions at the time of obfervation. “ My time would only permit me to take down the particular dimenfions of the moft capital inftrument, or the greater equinoftial fun-dial, reprefented by figure a, which appears to be an inftrument to exprefs folar time by the ftudow of a gnomon upon two quadrants, one fi- tuated to the eaft, and the other to the weft of it 5 and indeed the chief part of their inftruments at this place appear to be conftrufted for the fame purpofe, except the quadrants, and a brafs inftrument that will be de- feribed hereafter. “ Figure B is another inftrument for the purpofe of determining the exaft hour of the day by the fhadow of a gnomon, which ftands perpendicular to, and in the centre of, a flat circular ftone, fupported in an oblique fituation by means of four upright ftones and a crofs piece ; fo that the ffiadow of the gnomon, which is a perpendicular iron rod, is thrown upon the divifion of 15 ] OB T the circle deferibed on the face of the flat circular ftone. “ Figure c is a brafs circle, about two feet diameter, moving vertically upon two pivots between two ftone pillars, having an index or hand turning round horizon¬ tally on the centre of this circle, whicli is divided into 360 parts; but there are no counter diviftons on the in¬ dex to fubdivide thofe on the circle. This inftrument appears to be made for taking the angle of a ftar at fet- ting or rifing, or for taking the azimuth or amplitude of the fun at riling or fetting. “ The ufe of the inftrument, figure D, I was at a lofs to account for. It confifts of two circular walls ; the outer of which is about forty feet diameter, and eight feet high ; the rvall within about half that height, and appears intended for a place to ftand on to obferve the divifions on the upper circle of the outer wall, rather than for any other purpofe ; and yet both circles are di¬ vided into 360 degrees, each degree being fubdivided into twenty leffer divifions, the lame as the quadrants. There is a door-way to pafs into the inner circle, and a pillar in the centre, of the fame height with the lower circle, having a hole in it, being the centre of both circles, and feems to be a focket for an iron rod to be placed perpendicular into it. The divifions on thefe, as well as all the other inftruments, will bear a nice exami¬ nation with a pair of compaffes. “ Figure E is a fmaller equinoftial fun dial, conftruft¬ ed upon the fame principle as the large one a. “ I cannot quit this fubjeft without obferving, that the Bramins, without the affiftance of optical glafies, had neverthelefs an advantage unexperienced by the ob- fervers of the more northern climates. The ferenity and clearnefs of the atmofphere in the night-time in the Eaft: Indies, except at the feafons of the monfoons or periodi¬ cal winds changing, is difficult to exprefs to thofe who have not feen it, becaufe we have nothing in compari- fon to form our ideas upon : it is clear to perfeftion, a total quietude fubfifts, fcarcely a eloud to be feen, and the light of the heavens, by the numerous appearance of the ftars, affords a profpeft both of wonder and con¬ templation. “ This obfervatory at Benares is faid to have been built by the order of the emperor Ackbar : for as this wife prince endeavoured to improve the arts, fo he wiffied alfo to recover the fciences of Hindoftan, and therefore direfted that three fuch places ftiould be eredt- ed ; one at Delhi, another at Agra, and the third at Benares.” 0BSID1ANUS lapis, or Obsidian, a mineral fubftance. See Mineralogy Index. OBSIDIONALIS, an epithet applied by the Ro¬ mans to a fort of crown. See the article Crown. OBSTETRICS, or the Obstetric Art, the fame with Midwifery. OBS 1 RUC I ION, in Medicine, fuch an obturation of the veffels as prevents the circulation of the fluids, whether of the fqund and vital, or of the morbid and peccant kind, through them. OBTURATOR, See Anatomy, Table of the Mufcles. OBTUSE, fignifies blunt, dull, &c. in oppofition to acute or ffiarp. Thus we lay, obtufe angle, obtufe- angled triangle, &c. P 3 OBY, Obferva¬ tory II Obtufe. O C C [II Biack/1. Comment. OBY, or Ob, a large and famous river of Afiatic Ruflia, which iflues from the Altin lake (called by the Ruffians Telejkoi Ofero)y in latitude 52 degrees, and longitude 103 degrees 30 minutes. Its name fignifies Great; and accordingly in Ruffia it is often ftyled the Great River. The Calmucks and Tartars call it Umar. Its dream is very large and fmooth, its current being ufually flow; and it is in general between two and three hundred fathoms broad ; though in fome places it is much wider. It affords plenty of fiffi, and is navigable almofl: to the lake from which it fprings. After a long winding courfe through a vaft tra£l of land, in which it forms feveral iflands, it empties itfelf in latitude 67 de¬ grees, and longitude 86 degrees, into a bay, which, ex¬ tending near 400 miles farther, joins the Icy fea, in la¬ titude 73. 30. and longitude 90. The fprings from which this river rifes, are not very copious : but it re¬ ceives in its courfe the waters of a great number of con- fiderable ftreams. Of thefe, the Tom and the Irtis are the moft confiderable : the Tom falls into it in latitude 58. and the Irtis in latitude 61. and longitude 86. The exact courfe of this river was unknown till the country was furveyed by the Ruffians: who have given us toler¬ able maps of it and of all Siberia. The Oby forms the boundary between Europe and Afia, and its courfe is upwards of 2000 miles in length. OCCIDENT, in Geography, the wTeftward quarter of the horizon \ or that part of the horizon where the ecliptic, or the fun therein, defeends into the lower he- mifphere ; in\:ontradifl.in£lion to orient. Hence we ufe the word occidental for any thing belonging to the well 5 as occidental bezoar, occidental pearl, &c. Occident EJlival, that point of the horizon where the fun fets at midwinter, when entering the fign Ca¬ pricorn. Occident Equina Rial, that point of the horizon where the fun fets, when he crofles the equinoctial, or enters the fign Aries or Libra. OCCIPITAL, in Anatomy, a term applied to the parts of the occiput, or back part of the Ikull. OCCULT, fomething hidden, fecret, or invifible. The occult fciences are magic, necromancy, cabbala, &c. Occult qualities, in philofophy, were thofe qua¬ lities of body or fpirit which baffled the inveftigation of philofophers, and for which they were unable to give any reafonj unwilling, however, to acknowledge their ignorance, they deceived themfelves and the vul¬ gar by an empty title, calling what they did not know occult. Occult, in Geofnetry, is ufed for a line that is fcarce perceivable, drawn with the point of the compaffes or a- leaden pencil. Thefe lines are ufed in feveral opera¬ tions, as the raifing of plans, defigns of building, p mes of perfpeClive, &c. They are to be effaced when the Work is finiffled. OCCULTATION, mAjlronomy, the time a ftar or planet is hid from our fight, by the interpofition of the body of the moon or fome other planet. OCCUPANCY, in Law, is the taking poffeffion of thofe things which before belonged to nobody. This is the true ground and foundation of all Property, or of holding thofe things in feveralty, which by the law of nature, unqualified by that of foeiety, were common to all mankind. But, when once it was a- grecd that every thing capable of ownerfliip ftiould 6 ] O C C have an owner, natural reafon fuggefted, that he who Occupancy, could firft declare his intention of appropriating any ' —1 thing to his ufe, and, in confequence of fuch his in¬ tention, aftually took it into poffeffion, fhould there¬ by gain the abfolute property of it j according to that rule of the law of nations, recognized by the law’s of Rome, ^uod nullius ejl, id ratione naturali occupanti conceditur. This right of occupancy, fo far as it concerns real property, hath been confined by the laws of England within a very narrow compafs j and was extended only to a fingle inftance; namely, where a man was tenant pour autre vie, or had an eflate granted to himfelf only (without mentioning his heirs) for the life of another man, and died during the life of cejluy que vie, or him by whofe life it was holden : in this cafe he that could firfi: enter on the land, might lawfully retain the pof¬ feffion fo long as cejluy que vie lived, by right of occu¬ pancy. This feems to have been recurring to firft principles, and calling in the law of nature to afeertain the pro¬ perty of the land, when left without a legal owner. For it did not revert to the granter, who had parted with all his intereft, fo long as cejluy que vie lived ; it did not efeheat to the lord of the fee j for all efeheats muft be of the abfolute entire fee, and not of any par¬ ticular eftate carved out of it, much lefs of fo minute a remnant as this: it did not belong to the grantee j for he was dead : it did not defeend to his heirs $ for there were no words of inheritance in the grant : nor could it veft in his executors ; for no executors could fucceed to a freehold. Belonging therefore to nobody, like the hcereditas jacens of the Romans, the law left it open to be feized and appropriated by the firfl: perfon that could enter upon it, during the life of cejluy que vie, under the name of an occupant. But there was no right of occupancy allowed, where the king had the re- verfion of the lands : for the reverfioner hath an equal right with any other man to enter upon the vacant pof¬ feffion 5 and where the king’s title and a fubje&’s inter¬ fere, the king’s fhall always be preferred. Againft the king therefore there could be no prior occupant, becaufe nullum tempus occurrit regi. And, even in the cafe of a fubjeft, had the eftate pour autre vie granted to a man and his heirs during the life of cejluy que vie, there the heir might, and ftill may, enter and hold poffeffion, and is called in law a fpecial occupant; as having a fpecial exclufive right, by the terms of the original grant, to enter upon and occupy this hcereditas jacens, during the refidue of the eftate granted: though fome have thought him fo called with no very great propriety 5 and that fuch eftate is rather a defcendible freehold. But the title of common occupancy is now reduced almoft to no¬ thing b‘y two ftatutes 5 the one, 29 Car. II. c. 3. which enadls, that where there is no fpecial occupant, in whom the eftate may veft, the tenant pour autre vie may devife it by will, or it fhall go to the executors, and be affets in their hands for payment of debts : the other that of 14 Geo. II. c. 20. which enadls, that it ftiall veft not only in the executors, but, in cafe the tenant dies inte- ftate, in the adminiftrators alfo ; and go in courfe of a diftribution like a chattel intereft. By thefe two ftatutes the title of common occupancy is utterly extindl and aboliffled : .though that of fpecial oc¬ cupancy, by the heir at laiv, continues to this day } fuch heir O C C [i Occupancy, heir being held to fucceed to the anceftor’s eftate, not by defcent, for then he muft take an eftate of inheritance, but as an occupant, fpecially marked out and appointed by the original grant. The doftrine of common occu¬ pancy, may, however, be ufefully remembered on the following account, amongft others : That, as by the common law no occupancy could be of incorporeal he¬ reditaments, as of rents, tithes, advowfons, commons, or the like, (becaufe, with refpedl to them, there could be no aftual entry made, or corporeal feifin had ; and there¬ fore by the death of the grantee pour autre vie a grant of fueh hereditaments was entirely determined) : fo now, it is apprehended, notwithftanding thofe ftatutes, fuch grant would be determined likewife 5 and the heredi¬ taments could not be devifeable, nor veft in the execu¬ tors, nor go in a courfe of diftribution. For the ftatutes muft not be conftrued fo as to create any new eftate, or to keep that alive which by the common law was deter¬ mined, and thereby to defeat the granter’s reverfion j but merely to difpofe of an intereft in being, to which by law there was no owner, and which therefore was left open to die firft: occupant. When there is a refidue left, the ftatutes give it to the executors, &c. inftead of the firft occupant; but they will not create a refidue on purpofe to give it to the executors. They only mean to provide an appointed inftead of a cafual, a certain inftead of an uncertain, owner, of lands which before were nobody’s; and thereby to fupply this cafus omijfus, and render the difpofition of the lawr in all re- fpefts entirely uniform 5 this being the only inftance wherein a title to a real eftate could ever be acquired by occupancy. For there can be no other cafe devifed, wherein there is not fome owner of the land appointed by the law. In the cafe of a foie corporation, as a parfon of a church, when he dies dr refigns, though there be no a&ual owner of the land till a fucceflbr be appointed, yet there is a legal, potential, ownerftiip, fubfifting in contempla¬ tion of law ; and when the fucceflbr is appointed, his appointment fhall have a retrofpeft and relation back¬ wards, fo as to entitle him to all the profits from the in- ftant that the vacancy commenced. And, in all other inftances, when the tenant dies inteftate, and no other owner of the lands is to be found in the common courfe of defcents, there the law vefts an ownerfhip in the king, or in the fubordinate lord of the fee, by efcheat. So alfo, in fome cafes, where the laws of other nations give a right by occupancy, as in lands newly created, by the rifing of an iftand in a river, or by the alluvion or dereliftion of the fea ; in thefe inftances, the law of England afligns them an immediate owner. For Brae- ton tells us, that if an iftand arife in the middle oi a river, it belongs in common to thofe who have lands on each fide thereof; but if it be nearer to one bank than the other, it belongs only to him who is proprietor of the neareft fhore : which is agreeable to, and probably co¬ pied from, the civil law. Yet this feems only to be reafonable, where the foil of the river is equally divided between the owners of the oppofite fhores : for if the whole foil is the freehold of any one man, as it muft be whenever a feveral fiftiery is claimed, there it feems juft {and fo is the ufual practice) that the iilets, or little iilands, arifing in any part of the river, (hall be the pro¬ perty of him who owneth the pifcary and the foil. However, in cafe a new iiland rife in the fea, though the 3 17 ] O C E civil law gives it to the firft occupant, yet bur’s gives it Occupancy to the king. And as to lands gained from the fea j H either by alluvion, by the wafhing up of fand and earth, ■ c^an' ■ fo as in time to make terra firma ; or by derelidlion, as when the fea {brinks back below the ufual water mark} in thefe cafes the law is held to be, that if this gain be by little and little, by fmall and imperceptible de¬ grees, it (hall go to the owner of the land adjoining. For de minimis non curat lex : and, befides, thefe own¬ ers being often lofers by the breaking in of the fea, or at charges to keep it out, this poffible gain is there¬ fore a reciprocal cdnfideration for fuch poflible charge or lofs. But if the alluvion or dereliftion be fudden and confiderable, in this cafe it belongs to the king : for, as the king is lord of the fea, and fo owner of the foil while it is covered with water, it is but reafonable he fhould have the foil when the water has left it dry. So that the quantity of ground gained, and the time dur¬ ing which it is gained, are what make it either the king’s or the fubjedt’s property. In the fame manner, if a river, running between two lordftiips, by degrees gains upon the one, and thereby leaves the other dry, the owner who lofes his ground thus imperceptibly has no remedy : but if the courfe of the river be changed by a fudden and violent flood, or other hafty means, and thereby a man lofes his grounds, he {hall have what the river has left in any other place as recompenfe for this fudden lofs. And this law of alluvions and de- reliftions, with regard to rivers, is nearly the fame in the imperial law ; from whence indeed thofe our deter¬ minations feem to have been drawn and adopted : but we ourfelves, as iflanders, have applied them to marine increafes; and have given our fovereign the prerogative he enjoys, as well upon the particular reafons before mentioned, as upon this other general ground of prero¬ gative, which was formerly remarked, that whatever hath no other owner is verted by law in the king. See Prerogative. OCCUPANT, in Law, the perfon that firft: feizes or gets pofleflxon of a thing. OCCUPATION, in a legal fenfe, is taken for ufe or tenure : as in deeds it is frequently faid, that fucli lands are, or were lately, in the tenure or occupation of fuch a perfon.—It is likewife ufed for a trade or myftery. OCCUPIERS of Walling, a term ufed in the fait-works for the perfons who are the fworn officers that allot in particular places what quantity of fait is to be made, that the markets may not be overftocked, and fee that all is carried fairly and equally between the lord and the tenant. OCEAN, that huge mafs of fait waters which en- compafles all parts of the globe, and by means of which, in the prefent improved ftate of navigation, an eafy in- tercourfe fubfifts between places the moft diftant. The ocean is diftinguifhed into three grand divi- fions. 1. The Atlantic ocean, which divides Europe and Africa from America, which is generally about 3000 miles wide. 2. The Pacific ocean, or South fea, which divides America from Afia, and is generally about 10,000 miles over. And, 3. The Indian ocean, which feparates the Eaft Indies from Africa, which is 3000 miles over. The other feas, which are called oceans, are only parts or branches of thefe, and ufually receive their names from the countries they border uporn For O C E [II For the faltnefs, tides, &c. of the ix:can, fee the ar¬ ticles Sea, Tides, &c. OCEANIDES, in fabulous hiftory, fea nymphs, daughters of Oceanus, from whom they received their names, and of the goddefs Tethys or Thetis. They ■were 3000 according to Apollodorus, who mentions the names of feven of them j Alia, Styx, Eleftra, Donis, Eiuynome, Amphitrite, and Metis. Hcfiod fpeaks of the eldeit of them, which he reckons 41, Pitho, Adme- te, Prynno, Ian the, Rhodia, Hippo, Callirhoe, Urania, Clymene, Idyia, Palithoe, Clythia, Zeuxo, Galuxaure, Plexaure, Perfeis, Pluto, Thoe, Polydora, Melobofis, Dione, Cerceis, Xanthe, Acafta, Ianira,Teleftho, Euro- pa, Menelfho, Petroea, Eudora, Calypfo, Tyche, Ocy- roe, Crifia, Amphiro, with thofe mentioned by Apollo¬ dorus, except Amphitrite. Hyginus mentions 16, whofe names are almoft all different from thofe of Apollodo¬ rus and Heiiod •, which difference proceeds from the mu¬ tilation of the original text. The Oceanides, like the reft of the inferior deities, wrere honoured with libations and facrifices. Prayers were offered to them, and they were entreated to protect failors from ftorms and dange¬ rous tempefts. The Argonauts, before they proceeded to their expedition, made an offering of flour, honey, and oil, on the fea fhore, to all the deities of the fea, and facrificed bulls to them, and entroated their protec¬ tion. When the faerifice was made on the fea fhore, the blood of the victim was received in a veffel; but when it was in open fea, they permitted the blood to run down into the waters. When the fea was calm, they generally offered a lamb or a young pig ; but if it was agitated by the winds and rough, a black bull was deemed the moft acceptable vidtim. OCEANUS, in Pagan mythology, the fon of Coelus and Terra, the hufband of Thetis, and the father of the rivers and fountain1;, called Oceanides. The ancients called him the father of all things, imagining that he was produced by Humidity, which, according to Thales, was the firft principle from which every thing was pro¬ duced. Homer reprefents Juno vifiting him at the re- nioteft limits of the earth, and acknowledging him and Thetis as the parents of the gods. He was reprefented with a bull’s head, as an emblem of the rage and bel¬ lowing of the ocean when agitated by a ftorm. According to Homer, he . was the father even of all the gods, and on that account he received frequent vifits from them. He is often, indeed almoft always, repre¬ fented as an old man with a long flowing beard, and fit¬ ting upon the waves of the fea. He often holds a pike in his hand, while fhips under fail appear at a diftance, or a fea monfter ftands near him. Oceanus prefided over every part of the fea, and even the rivers were fub- jeffed to his power. The ancients were fuperftitious in their worfhip of him, and revered with great folemnity a deity to whofe care they intrufted themfelves when going on any voyage. OCEIA, a woman who prefided over the facred rites of Vefta for 57 years with the greateft fanffity. She died in the reign of Tiberius, and the daughter of Ho- mitius fucceeded her. OCELLUS the LuCANIAN, an ancient Greek philo- fopher of the fchool of Pythagoras, who lived before Plato. His work vigi rev Hallos, or “ The Univerfe,” is the only piece of his which is come down entire to us j and was written originally in the Doric dial eft, but 4 8 ] OCT was tranflated by another hand into the Attic. Wxl- Geelluv liam Chriftian, and after him Lewis Nogarola, tranfla- il ted this work into Latin ; and we have ieveral editions , a^on* of it, both in Greek and Latin. OCELOT, the Mexican cat. See Feus, Mamma¬ lia Index. OCHLOCRACY, that form of government where¬ in the populace have the chief adminifl ration of af¬ fairs. OCHNA, a genus of plants belonging to the poly- andria clafs ; and in the natural method ranking with thofe of which the order is doubtful. See Botany Index. OCHRE, in Natural Hijlory, a mineral fubftance compofcd of oxide and carbonate of iron, and clay. See Ores of Iron, Minf-Ralogy Index. OCHROMA, a genus of plants belonging to the monadelphia clais •, and in the natural method ranking under the 37th order, Colwmiferce, See Botany In¬ dex. OCHUS, a king of Perfia, fon of Artaxerxes. H« was cruel and avaricious ; and in order to ftrengthen himfelf on his throne, he murdered all his brothers and lifters. His fubjefts revolted ; but he reduced them to obedience, and added Egypt to his other do¬ minions.. Bagoas, his favourite eunuch, poifoned him for the infults he had offered to Apis the god of the Egyptians •, and he gave his flefh to be eaten by cats, and made handles for knives with his bones. It feems to be not a little remarkable, that all thofe monfters who difgraced humanity by their crimes, and funk themfelves below the level of brutes, have met with condign puniftunent •, and this in general feems true, whether we refer to ancient or modern times.—A man of Cyzicus, who was killed by the Argonauts.—A prince of Perfia, who refufed to vifit his native country for fear of giving all the women each a piece of gold.— A river of India or of Baftriana —A king of Perfia : He exchanged this name for that of Darius Nothus. See Persia. OCRA, a vifeous vegetable fubftance well known in the Weft Indies, where it is ufed to thicken foup, parti¬ cularly that kind called pepper pot, as well as for other purpofes. OCRISIA, in fabulous hiflory, the evife of Cornicu- lus, was one of the attendants of Tanaquil the wife of Tarquinius Prifcus. As (he was throwing into the flames, for offerings, fome of the meats that were ferved on the table of Tarquin, lire fuddenly faw, as is report¬ ed, in the fire, what Ovid calls obfeeeni forma virilis. She informed the queen of it j and when by her com¬ mand Ihc had approached near it, fhe conceived a fon who was named Servius Tullius, and was educated in the king’s family. He afterwards fucceeded to the va¬ cant throne. Some fuppofe that Vulcan had affumed that form which was prefented to the eyes of Ocrifia, and that this god was the father of the fixth king of Rome. OCTAETERIS, a cycle or term of eight years, in the Grecian chronology, at the conclufion of which three entire lunar months were added. This cycle was in ufe till Melon’s invention of the golden number or cycle of 19 years. OCTAGON, or Octogon, in Geometry, is a figure of eight fides and angles j and this, when all the iides and OCT [ i Odtavia. ©dragon and angles are equal, is called a regular* o^iagon^ or one 11 that may be inferibed in a circle. , Octagon, in Fortification, denotes a place that has eight baftions. See Fortification. OCTAHEDRON, or Octaedron, in Geometry, one of the five regular bodies, confiding of eight equal and equilateral triangles. OCTANDRIA {hktu, 11 eight,” and a “ man or hufband,”) the 8th clafs in Linnaeus’s fexual fyftem j eonfifting of plants which are furniftied with eight fta- mina. See Botany Index. OCTANT, the eighth part of a circle. Octant, or Octile, in AJlronomy, that afpeft of two planets, Avherein they are diilant an eighth part of a circle, or 450 from each other, OCTAPLA, in matters of facred literature, denotes a Polyglot Bible, confifting of eight columns, and as many different vtrfions of the facred text; viz. the ori¬ ginal Hebrew both in Hebrew and Greek characters, Greek verfions, &c. OCTATEUCH, an appellation given to the eight firft books of the Old Teftament. OCTAVE, in Mufic. See Interval. OCT AVI A, daughter of Caius Octavius and filter to Augultus Caefar. See the following article. She was one of the molt illuftrious ladies of ancient Rome ; her virtues and her beauty were equally confpicuous. Prideaux fays Ihe was much handfomer than Cleopatra. She married Claudius Marcellus, and after his death M. Antony. Her marriage with Antony was a political match, to reconcile her brother and him together. An¬ tony proved for fome time attentive to her: but when he had feen Cleopatra, he negle&ed and defpifed her: and when (lie attempted to withdraw him from this ille¬ gal amour by going to meet him at Athens, (lie was re¬ buked and totally banilhed from his prefence. This af¬ front was highly refented by her brother ; and though Gdtavia endeavoured to pacify him by palliating Anto¬ ny’s behaviour, yet he refolved to revenge her caufe by arms. After the battle of A&ium and the death of Antony, 06tavia, forgetful of her own injuries, took into her lioufe all the children of her hulband, and treated them with extraordinary tendernefs. Marcellus, her fon by her firft hufband, was married to a niece of Auguftus, . and openly intended as a fucceffor to his uncle. His fudden death plunged all the family into the greateft grief. Virgil, whom Auguftus patronized, undertook of himfelf to pay a melancholy tribute to the memory of a young man whom Rome had looked upon as her future father and patron. He was defired to re¬ peat his compofition in the prefence of the emperor and his fifter. Oftavia burft into tears even when the poet began j but when he mentioned Tu Marcellus eris, flie Avooned away. This tender and pathetic encomium upon the merit and the virtues of young Marcellos fhe liberally rewarded 5 and Virgil received 10,000 fefterces, according to fome 781. 2s. 6d. for every one of the ver- fes.. Octavia* had two daughters by Antony, Antonia Major and Antonia Minor.—The elder married L. Domitius Ahenobarbus, by whom fire had Cn. Do- imtius, who was the father of the emperor Nero by Agrippina the daughter of Germanicus. Antonia Mi¬ nor, who was as virtuous and as beautiful as her mother, married Drufus the fun of Tiberius, by whom ftie had Germanicus,. anc^ Claudius who reigned before Nero. 19 ] OCT I he death of Marcellus conftantly preyed upon the 0 generufity, and magnanimity.” He faid . u “ . he painted thefe charafters for the fenate’s informa¬ tion, defiring they would choofe which of the young princes they believed would render the kingdom hap- pieft. It was a matter which would admit of no he- lltation with one voice the fenate declared for that prince whofe panegyric the father had To warmly drawn j and under thefe happy aufpices commenced the origin of the grandeur of the houfe ot Oldenburg, at this day featcd on the throne of Denmark. Oldenburg, Henry, a learned German of the 17th century, was defcended from the noble family of his name, who were earls of the county of Oldenburg, in the north part of Weftphalia, for many generations. He was born'in the duchy of Bremen in the Lower Saxony *, and during the long Englifh parliament in King Charles I.’s time, was appointed conful for his countrymen,at London,after the ufurpationof Cromwell; but. being difcharged of that enjploy, he was made tutor to the lord Henry O’Bryan, an Iritb nobleman, whom he attended to the univerfity of Oxford, where he was admitted to ftudy in the Bodleian library in-the begin¬ ning of the year 1636. He was afterwards tutor to William lord Cavendith, and was acquainted with Ptlil- ton the poet. During his refidence at Oxford, he be¬ came alfo acquainted with the members of that body there, wdiich gave birth to the Royal Society ; and upon the foundation of this latter, he was elefted fellow ; and when the fociety found it neceflary to have two fecre- taries, he was chofen affiftant fecretary to Dr Wilkins. He applied himfelf with extraordinary diligence to the bufinefs of his office, and began the publication of the Philofophical Tranfaftions with N° I. in 1664. In order to difcharge this talk with greater credit to him¬ felf and the fociety, he held a correfpondence with more than feventy learned perfons, and others, upon a vaft variety of fubjefts, in different parts of the world. This fatigue would have been infupportable, had not he, as he told Dr Lifter, managed it fo as to make one letter anfwer another ; and that to be always frefti, he never read a letter before he had pen, ink, and paper, ready to anfwer it forthwith ; fo that the multitude of his letters cloyed him not, nor ever lay upon his hands. Among others, he was a conftant correfpondent of Mr Robert Boyle, with whom he had a very intimate friendfhip ; and he tranllated feveral of that ingenious gentleman’s works into Latin. Mr Oldenburg continued to publiffi the Tranfaftions, as before, to N° xxxvi. June 25. 1677. After the publication was difcontinued till the January fol¬ lowing, when it was again refumed by his fucceffor in the fecretary’s office, Mr Nehemiah Grew, who car¬ ried it on till the end of February 1678. Our author dying at his houfe at Charleton, near Greenwich in Kent, in the month of Auguft that year, was interred there. OLDENL ANDI A, a genus of plants belonging to the tetrandria clafs. See Botany Index. OLDHAM, John, an eminent Engliffi poet in the 17th century, fon of a Nonconformift minifter, w’as edu¬ cated under his father, and then fent to Edmund-hall in Oxford. He became uffier to the free-fchoo! at Croy¬ don in Surry : where he received a vifit from the earls ginous. of Rocbeffer and Dorfet, Sir Charles Sedley, and other Oldham perfons of dihinbtion, merely upon the reputation of^ >1 fome verfes of his which they had feen in manufoript. He was tutor to feveral gentlemen’s fons fucceffively ; and having faved a fmall turn of money, came to Lon¬ don, and became a perfect votary to the bottle, being an agreeable companion. He was quickly found out here by the noblemen who had viftted him at Croydon, Avho brought him acquainted with Mr Dryden. He lived moltly with the earl of Kingfton at Holme-Pier- point in Nottinghamihire, where he died ot the fmall- pox in 1683, in the 30th year of his age. His acquaint¬ ance with learned authors appears by his fatires againft the Jefuits, in which there is as much learning as wit difeovered. Mr Dryden efteemed him highly. His works are printed in 2 vols i2mo. They chiefly conlift of fatires, odes, tranflations, paraphrafos of Horace and other authors, elegfoc verfes, imitations, parodies, fami¬ liar epiftles, &c. OLD-HE AD, a promontory fituated in the county of Cork, and province of Munlter, four miles foutb of Kinfale, in the barony of Courcies, Ireland, which runs far into the lea, and on wlfich is a lighthoufe lor the convenience of Hupping. A mile from its extremity is an ancient caftle of the lords of Kinfale, built from one fide of the ifthmus to the other, which defended all the lands torvards the head : this place Avas formerly called Dunceanna, and Avas the old leat of the Irilh kings. The ifthmus, by the working of the fea, Avas quite pe¬ netrated through, lo as to form a ftupendous arch, un-' oer Avhich boats might pafs from one bay to the other. Among the rocks of this coaft there are aviaries of good hawks : alfo the lea eagles or ofpreys build their nefts and breed there. OLDMIXON, John, Avas defcended from an an¬ cient family in Somerfctlhire : he Avas a violent party- Avriter and malevolent critic, Avho Avould learcely have been remembered, if Pope, in refontment of his abufe, had not condemned him to immortality in bis Dun- ciad. His party-Avritings procured him a place in the revenue at Liverpool, Avhere he died at an advanced age in the year 1 745. Bolides his fugitive temporary pieces, he wrote a Hiltory of the Stuarts, in folio; a Critical Hiftory of England, 2 vols 8vo ; a volume of Poems, fome dramatic pieces, &c. ; none of them wor¬ thy of notice, his principal talent being that of falffty- ing hiftory. Old-wife, or Wrajfe. See Labrus, ] Ichthyolo- Old-WIFE Fifh. See Balistes, GY Index. Old-woman’s island, a narroAV flip of land, about two miles long, feparated from Bombay in the Eaft In¬ dies by an arm of the fea, Avhich, however, is paffable at Ioav Avater. It terminates at one extremity in a final! eminence, on Avhich a look-out houfe is kept for veffels. Near the middle are three tombs kept conftantly Avhite as land-marks into the harbour. From the end of the illand a dangerous ledge of rocks Ihoots forth, Avhich are not very eaffly cleared. It produces only pafture for a few cattle. OLE A, the olive-tree ; a genus of plants belonging to the diandria clafs ; and in the natural method ranking under the 44th order, Sepiarice. See Botany Index.. OLEAGINOUS, fomething that partakes of the nature of oil, or out of Avhich oil may be expreffed. OLEANDER, O L I [ 131 ] O L I Oleander OLEANDER, or Rose Bay, nerium ; a germs of II plants belonging to the pentandria clafs. See Botany , ^10' , Index. v OLECRANUM, or Olecranon, in Antitimt/, the protuberance of the ulna, which prevents the joint of the elbow from being bent back beyond a certain length. See Anatomy, N° 51. OLENUS, a Greek poet, older than Orpheus, catnb from Xanthe, a city of Lycia. He compofed feveral hymns, which were fung in the ifland of Delos upon fe¬ lt ival days. Olenus is faid to have been one of the founders of the oracle at Delphi; to have been the firfl who filled at that place the office of pried of Apollo ; and to have given refponfes in verfe : but the truth of thefe aflertions is very doubtful. OLERON, an ifland of France, on the coad of Au- nis and Saintogne, about five miles from the continent. It is 12 miles in length, and five in breadth j and is very fertile, containing about 12,000 inhabitants, who are excellent feamen. It is defended by a cadle, which is well fortified j and there is a lighthoufe placed there for the dire&ion of fhips. It is 14 miles fouth-ead of Rochelle. W. Long. 1. 26. N. Lat. 46. 3. Sea Laws of OLERON, certain laws relative to mari¬ time affairs, made in the time of Richard I. when he was at the ifland of Oleron. Thefe laws, being accounted the mod excellent fea laws in the World, are recorded in the black book of the admiralty. See Selden’s Mare Claufum. OLEUM palm® CHRISTI, commonly called cajlor oil, is extra&ed from the kernel of the fruit produced by the Ricinus Americanus. See RlciNUS, Botany and Materia Medic a Index. OLFACTORY nerves. See Anatomy, N°i39 and 143. OLGA, queen of Igor, the fecond monarch of Ruf- fia, who flouriflied about the year 880, having fucceed- ed his father Ruric, who died in 878. Olga was born in Plefcow, and Was of the bed family in that city. She bore him one fon, called Swetcflaxv. Igor being1 mur¬ dered by the Drewenfes, or Drewliani, Olga revenged his death. She went afterwards, for what reafon we know not, to Conflantinople, where (he was baptized, and received the name of Helena. The emperor John Zimifces w'as her godfather, and fell in love with her as we are told ; but (he, alleging their fpiritual alliance, refufed to marry him. Her ex¬ ample made fome impreflion upon her fubjedfls, a good number of whom became converts to Chridianity ; but none upon her fon, who reigned for a long time after her death, which happened at Pereflaw, in the 80th year of her age, 14 years after her baptifm. The Ruf¬ fians to this dav rank her among their faints, and com¬ memorate her fedival on the nth of July. OLIBANUM, in Pharmacy, a gumipy refin, (the product of dne juniperus lycia Lin.), brought from Tur¬ key and the Ead Indies, ufually in drops or tears. See Materia Medica Index. OLIGARCHY, a form of government wherein the adminifiration of affairs is confined to a few hands. OLIO, or Oglio, a favoury difh, or food, compofed of a great variety of ingredients j chiefly found at Spa¬ in fh tables. The forms of olios are various. To give a notion of this drange affemblage, we (hall here add one from an approved author. r.-ike rump of beef, neats tongues boiled and dried, and Bologna faufages ; boil them together, and, after boiling two hours, add mutton, pork, venifon and ba¬ con, cut in bits 5 as alfo turnips, carrots, onions and cabbage, borage, endive, marigolds, forrel, and fpi nach ; then (pices, as faffron, cloves, mace, nutmeg, &c. This done, in another pot put a turkey or goofe, with capons, pheafants, wigeons and ducks, partridges, teals, and dock-doves, fnipes, quails, and larks, and boil them in water and fait. In a third veffel, prepare a fauce of white wine, drong broth, butter, bottoms of artichokes, and chefnuts, with cauliflowers, bread, mar¬ row', yolks of eggs, mace, and faffrort. Ladly, Di(h the olio, by fird laying out the beef and veal, then the venifon, mutton, tongues, and faufages, and the roots over all ; then the larged fowls, then the fmalled, and ladly pour on the fauce. OLISIPO, (Pliny, Antonine, Infcriptions) j a town of Lufitania, fituated on the north fide of the frith of the Tagus ; of fuch antiquity, that Solinus thought it was built by Ulyffes 5 and Mela, probably to favour this opinion, writes, according to the common copies, Vlyfipo ; both of them perhaps deceived by the fimila- rity of found. It was a municipium, with the furname Felicit as Julia, a privilege granted by the munificence of Augudus, (Inferiptions, Pliny). Now Lifhon, ca¬ pital of Portugal, fituated on the north bank of the Tagus, diflant about ten miles from its mouth. See Lisbon. OLIVAREZ, CouNt DE, by name Don Gafpar de Guzman, favourite and minider to Don Philip IV. of Spain, about 1620 j a man of great parts and boundlels ambition. Philip no fooner became king, than he be¬ came the fubjeft of this his favourite. The king had abilities, it is true, but they lay dormant; and wdiilft he fpent his time in lidlefs inaflivity, the whole govern¬ ment was under the direclion of Olivarez. The count’s management, indeed, Avas fufficiently dexterous in ac- complifliing his oivn defigns^ for by the bed framed ex- cufes, and on the mod plaufible pretexts, he removed all fuch as he thought flood in his way ; nor did he flop there, but fometimes perfecuted his rivals even to death, of Avhich Don Rodrigo Calderona xvas a melancholy in¬ flame, an inflance ivliich at that time excited univerfd compaflion. This minider, in (hurt, had a genius of no common kind ; added to Avhich, he had a difpofition Avhich fpurned all controul. # He had perfecuted the late minidry for their pufilla- mmity in the management of affairs ; he therefore thought it neceffary, and it Avas certainly prudent, to purfue new meafures. His felf-fufficiency, though un¬ bounded, Avas concealed under the veil of affumed mo- defly, and he Avas careful to make it appear that he Avas wholly taken up Avith the things of his oAvn province. His politics were of a refined perhaps, but not of a very ufeful, tendency ; for his imprudence, or his Avrong no¬ tions on the fubjeft, made him reneAV a Avar Avith HoF land, contrary to the univerfal opinion of the council and the people. By the fame imprudence, or by fome- thing worfe, he provoked England, and obliged her to endeavour to humble the pride and leffen the authority of the houfe of Auffria. Thus far he had been of little R 2 fervice OKo Olivarez. O L I [ 132 ] O L I Olivarez, fervice to Ms country, having only provoked the refent- -y—' ment of the moft powerful Hates, particularly England, France, Holland, &c. to conlpire for its ruin. It is re¬ markable that Olivarez, notvvithftanding this, never loft his credit } and indeed things fo turned about in the end, that though Spain for a whole year was put to the fevered trials, it acquired a degree of fame which fuffi- ciently, in the general opinion, overbalanced fome lit¬ tle lofs. Olivarez too was particularly fortunate in making the peace } in which tranfaftion he gained a very confiderable advantage over Richelieu, fo that things appeared to be ftill in a very favourable train. Fortune, however, was not always quite fo indulgent to the fchemes of this minifter : he again drew Spain into a war with Mantua, contrary to the fentiments of the ■vvifeft men ; from which is juftly dated its declenfion, if not its ruin. On the whole, Olivarez feems to have been always averfe to peace ) and with fuch a reftlefs difpofitioii, it is undoubtedly wonderful that he held his place fo long and with fo few complaints as he did. It was certainly owing to his ambition and obftinacy, that an almoft general war was excited about the year 1627, and which, as we have faid, proved fo fatal to Spain. So averfe, indeed, does he appear to have been to peace, that he ufed every means in his power to pre¬ vent the reftoration of it in Italy ; and for this very pur- pofe he fent Feria into Milan, whom he knew to be a man of fuch a temper and abilities as fuited his purpofes; for he was naturally averfe to quiet. He endeavoured to break the alliances of the duke of Mantua by various flratagems 5 but they did not fucceed :' the fchemes of Olivarez and the intrigues of Feria being totally defeat¬ ed. Our minifter had foon after this another caufe of mortification, on Richelieu’s being created a duke and peer of France, and unanimoufty admitted among the Venetian nobility j which could not fail to be a fevere ftroke on Olivarez, who conlidered him as his implaca¬ ble enemy. The people at length began to fee and be difpleafed with his conduct j and with reafon, had they known it all, for it was in many inftances cruel and deteftable. Indeed the differences which at that time had fo long fubfifted between France and Spain were the effeft of the private animofity between him and Richelieu. Things, however, fo turned about, and Spain was fo unufually fuccefsful, that the faults of the minifter were overlooked for the time ; but this unexpected good for¬ tune had no other effeCt than that of making him far more infolent than ever. He was, in every inflance, one of the moft -headlVong and obftinate men in the world : he had fet his heart on the reduction of Cafal in Italy, and he'was determined on it at whatever ha¬ zard •, this foolifh enterprife was, however, unaccount¬ ably defeated, and the Spanilh army experienced a total defeat. The revolt of the Catalans, whom he wilhed to de¬ prive of their privileges, was the next confequence of his folly : he had privately employed the marquis de los Velez to extinguilh this rebellion *, but the cruelty of the meafures ufed for this purpofe only inflamed it the more. The revolution of Portugal, another dif- aftrous event, was alfo the refult of his obftinacy and rigour. » This feries of ill fortune, which ought to have opened the eyes of the Catholic king and his minifters, feemed Olivarez to infatuate both. The great fecret by which Olivarez li had governed his mafter was being the companion, or at leaf! the confidant, of his pleafures. W hile he affe&ed . ^ to deceive the world with a fpecious appearance of reli¬ gion and piety, he was not only immerfed in vice him- lelf, but encouraged and promoted it in his prince, to the fcandal of his lubjefls, and the prejudice of his af¬ fairs. At this time, of all others the moft improper, Olivarez produced a baftard of his, hitherto called Ju¬ lian ; he had taken fo little care of this fon, that, not able to fubfift in Spain, he had palled over to the Indies, where, in very mean ilations, he had fcarcely got bread. On him he now bellowed the name of Dun Henrico de Guzman; and bringing him with great pomp and fplendour to court, either flattered of forced the con- ftable of Cauile to give him his daughter ; in confidera- tion of which alliance he was to devolve upon him his duchy of St Lucar. In the beginning of his adminillra- tion, by fome accident or other, he prefen ted to the king a memorial, in relation to an affair upon which his majefty had already received one from Don Balthafar de Zuniga : upon comparing them, they contradicted each other flatly. The king ordered a perfon of great quality to inquire thoroughly into this bufinefs 5 in con¬ fequence of which Don Balthafar’s memorial appeared to be the truth, and that of Olivarez the reverfe of it. The king was very angry j but the count regained his favour, by procuring for him the fair aftrefs Calderona. By this woman he had a fon, of whom no great notice was taken j but now, to obfeure the folly of the count duke, this youth, fcarce in the 14th year of his age, was produced, with the title of Don Juan of Aujlria> and declared generaliflimo of the army againft Portugal j while the heir apparent to the crown, Don Balthalar, was left under the tuition, or rather in the cuftody of the countefs of Olivarez ; at which conduft the queen was chagrined, the people enraged, and the world in general aftoniftied. His fchemes now began to be entirely broken and defeated everywhere and in every kind ; he fell under the difpleafure of the queen, the emperor, the grandees, and the people all at once, and experienced the difgrace he had long merited. His ill fortune, which came up¬ on him with the force of a torrent, did not, however, wholly overpower him j he was indeed obliged to con¬ ceal himfelf, in order to avoid the rage of the populace : but he had ftill confidence enough to offer an apology for his conduCl, which poffeffed no inconfiderable Ihare of wit and humour, well tempered with fpirit and ma- fterly reafoning. It was not, however, of any confe- quence to him } for he was baniftied to ’loro, where, worn out by infirmities, or overcome by defpair, he end¬ ed his days about the year 1645. OLIVE, the fruit of the olive tree. See Olea, Bo¬ tany Index. Olive Prefs. In order to obtain the olive oil, the pIate olives are firft bruifed in a rough trough, under a mill- CCCLXX Hone, rolling perpendicularly over them ; and when fufficientiy maftied, put into the maye or trough, m, of an olive prefs, where a a are the upright beams, or cheeks ; b, the female, and f, the male ferew j /, the board on which the ferew paffes ; g, a cubical piece of wood, called a block; //, the peel, a circular board, to be put under the block. By turning the ferew, aft the liquor o L I [ 133 ] O L Y Olive liquor is prefled out of the maflied olives, and is called Prefs virgin oil; after which, hot water being poured upon Olivet an t^ie remainder in the prefs, a coarfer oil is obtained. > Olive oil keeps only about a year, after which it dege¬ nerates. OLIVE Colour, a yellow mingled with black. OLIVET, or Mount of OLIVES, in Ancient Geogra¬ phy, was fituated to the eait of the city of Jerufalem, and parted from the city only by the brook Kidron, and by the valley of Jehoihaphat, which It retches out from the north to the fouth. It was upon this mount that Solomon built temples to the gods of the Ammonites (1 Kings xi. 7.) and of the Moabites, out of compiai- fance to his wives, who were natives of thefe nations. Hence it is that the mount of Olives is called the moun¬ tain of corruption (2 Kings xxiii. 13.). Jofephus fays, that this mountain is at the diftance of five itadia, or furlongs, from Jerufalem, which make 625 geometrical paces, or the length of a Sabbath day’s journey, fays St Luke (Adis i. 12.). The mount of Olives had three fummits, or was compofed of three feveral mountains, ranged one after another from north to fouth. The middle fummit is that from whence our Saviour afcend- ed into heaven. It was upon that towards the fouth that Solomon built temples to his idols. The fummit •which is moll to the north is dillant two furlongs from the middlemoft. This is the higheft of the three, and is commonly called Galilee. In the time of King Uzziah, the mount of Olives was fo fhattered by an earthquake, that half of the earth that was on the weftern fide fell down, and rolled four furlongs er 500 paces from thence, towards the mountain which was oppofite to it on the eaft ; fo that the earth blocked up the highways, and covered the king’s gardens. Mr Maundrell tells us that he and his company going out of Jerufalem at St Stephen’s gate, and eroding the valley of Jehoihaphat, began immediately to afeend the mountain ; that being got above two-thirds of the way up, they came to certain grottoes cut with intricate windings and caverns under ground, which were called the fepulchres of the prophets ; that a little higher up were twelved arched vaults under ground, Handing fide by fide, and built in memory of the apoliles, rvho are faid to have compiled their creed in this place ; that 60 paces higher they came to the place where Chrift is faid to have uttered his prophecy concerning the final deltruftion of Jerufalem 5 and a little on the right hand, to another, where he is faid to have dictated a fecond time the Lord’s prayer to his difciples j that fomewhat higher is the cave of a faint called Pelagia; a little above that, a pillar denoting the place where an angel gave the Bleffed Virgin three days warning of her death •, and at the top of all, the place of our blefled Lord’s afeenfion. OLIVET AN, Robert, related to the famous Cal¬ vin, printed at Neufchatel in -I 535, in folio, a verfion of the Bible into French, the firlt which had been iranlla- ted from the original Hebrew and Greek. It is writ¬ ten in an uncouth and barbarous ftyle, and is far from being faithful. The charadlers in which it is printed are Gothic, and the language of it is no lefs fo. It is valued only becaufe it is rare. Calvin is thought to have had a very confiderable (hare in this tranllation. Olivetan furvived his publication but a fiiort time j for he was poifoned at Rome the year after, of which his Olivetan tranllation is alleged to have been the caufe. Olivetan’s II Bible, revifed by John Calvin and N. Malinger, was Oty^pia. reprinted at Geneva, in 1540, in quarto. This edition V is Hill rarer than the former. It is called the Bible de I'Epee, becaufe the printer had a (word for his fign. OLIVIER, Claude Matthieu, advocate of the parliament of Aix, was born at Marfeilles in 1701, and appeared at the bar with eclat. He had a chief hand in the eftablilhment of the academy of Marfeilles, and was one of its original members. He pofieffed a quick and lively genius. A few hours retirement from fociety and from his pleafures were frequently fufficient to en¬ able him to ipeak and write, even on important caufes; but his works commonly bore marks of halle. Given to excels in every thing, he would employ a fortnight in lludying the Code and the Digelt, or in lloring his mind with ihe beauties of Demolthenes, Homer, Cice¬ ro, or Boffuet : and then abandon himfelf for another fortnight, frequently a whole month, to a life of frivo¬ lity and diffipation. He died in 1736, at the age of 3 5- He publilhed, 1. L’Hifotre de Philippe rot de Ma¬ cedoine, et pere d'1 Alexandre le Grand, 2 vols i2mo. No writer has fo ably handled the hiltory of the age of Philip, the interells of the different nations of Greece, and their manners and culloms : but the condufl of the work is extremely defedlive. The digreflions are too frequent, and often tedious. The llyle is in no refpedl fuitable to a hiltory. It is in general dry, unconnected, and like the ityle of a differtation. Sometimes, how¬ ever, we find in it palfages full of fire and beauty, and turns of expreffion truly original. A difeafe of the brain, with which he was attacked, and under which he laboured feveral years, prevented him from putting his lalt hand to the work. 2. Me'moire fur les fecours donnes aux Remains par les Marfeillois pendant la ide Guerre P unique. 3. Me'moire fur les fecours donnes aux Remains par les Marfeillois durant la Guerre centre les Gau/uis. OLMUTZ, a town of Germany, in Moravia, with a bilhop’s fee, and a famous univerfity. The public buildings are very handfome, particularly the Jefuits col¬ lege. It is a populous, trading, and very Itrong place } and yet it was taken, with the whole garrifon, by the king of Prulfia in 1741. In July 1758 he befieged it again •, and when he had almolt taken the place he was obliged to raife the fiege, to go and meet the Ruffian army. It is feated on the river Morave. E. Long. 17. 35. N. Lat. 49. 30. OLYMPIA, Maldachini Donna, a woman of a very uncommon charaCter. She flouriffied about the middle of the 17th century. She was filter-in-law to Pope Innocent X. and had the addrefs to acquire an un¬ limited power over this vain, weak, and injudicious ecclefialtic. Her fon Camillo was promoted to the cardi- nalate, under the title of Pamphilio ; but falling in love with the princefs Rofiana, a beautiful young widow, he laid afide his hat, and married. The crime, if it was one, was elteemed by the Romans in general at lealt ve¬ nial. The pope, however, was difpleafed ; and Olym¬ pia procured their banilhment, being afraid left her daughter in-law fliould lelfen her authority in thefacred court. This authority, equally unnatural and uncom¬ mon, reflected neither honour on her who held it, nor on the man who allowed her to hold it. Such elevated fituationsj O L Y T 134 1 O L Y Olymplfl. fituations, however, whether they are the reward of merit, the etfeft of chance, or acquired by cunning, are feldom very fecure. Olympia, who had procured the difgrace of many who did not deferve it, and who had herfelf long merited fueh a fate, at length experi¬ enced both difgrace and banilhment. This was obtain¬ ed by means of Cardinal Panzirollo, a great favourite of the pope’s. The immediate caufe of it was this : The pope had determined, in order to leffen his owrn trouble, to adopt a nephew, and to make him a Cardinal Pa¬ tron, in order to give audience to ambaffadors and mi- nifters, and in his abfence to prefide at the council. For this purpofe, at the recommendation of his favourite, his holinefs make choice of Aftalli, brother of the mar¬ quis Aftalli, who had married a niece of Olympia. Olympia indeed was {lightly confulted on the affair, and fhowed 'no difapprobation of the appointment. Tire pope, however, no fooner got him fixed in his new of¬ fice, than he fhowed his own weaknefs by repenting of it. Olympia too was difpleafed, and by her felicitations procured the difgrace of Aftalli, before had enjoyed ei¬ ther the honours or emoluments of his office. Panzi¬ rollo, however, foon managed matters fo as to turn the fcales : he prevailed on the pope again to countenance 3 , and honour Aftalli; and, what was more, had influence fufficient to perfuade him to difgrace Olympia, and to banifh her the court. She had indeed abufed her autho¬ rity in a moft fcandalous manner, and had gained fuch an abfolute afeendant over the pope, that in every thing his will had been fubfervient to her dictates.—Pier ava¬ rice and ambition were unbounded : fhe difpofed of all benefices, which Avere kept vacant till fhe fully inform¬ ed herfelf of their value: fhe rated an office of 1000 crowns for three years, at one year’s revenue, and if for life, at 1 2 years purchafe, one half of which fum fhe required to be paid in advance : fhe gave audience upon public affairs, enafted new laws, abrogated thofe of former popes, and fat in council with Innocent, with bundles of memorials in her hands. It was generally laid that fhey lived together in a criminal correfpond- tnee, and that fhe had charmed him by fome fecret in¬ cantation. In the Proteftant countries the loves and intrigues of Innocent and Donna Olympia were repre- fented upon the ftage •, and fevere farcafms Avere daily put into the hands of Pafquin at Home.-—As fire had ufurped fuch an abfolute authority, the neAV cardinal nephew faw the neceffity of ruining her credit; he therefore feconded the endeavours of Panzirollo.—He infinuated to the pope, that his reputation had fuffered greatly among the Catholics by her fcandalous proceed¬ ings, and that his nuncios were treated with difrefpeft and contempt at the courts of the emperor, France, and Spain. Upon thefe reprefentations, Innocent at length, but Avith great reluftance, banifhed Olympia, and Avas reconciled to Prince Camillo and the prittcefs Roffana; though fome authors affirm that her banifhment was no more than a political retreat, and that fhe ftill in pri¬ vate direfted the affairs of the pope. A Avoman of O- lympia’s chara&er, hoAvever, Avith fueh unbounded am¬ bition, fuch an extravagant luft for power, and fuch an * ambitious defire of Avealth, and who had once poffeffed fo great an afcendcncy over fuch a man as Innocent, Avas not to be fo eafily put off. She Avas banifhed in 1650 5 but in 1653, A16 again afiumed the fupreme di¬ rection of affairs juft as before her difgrace. She again Olympia, accomplifhed the difgrace of Aftalli, and procured the promotion of Azzolini to the office of fecretary of the briefs. In 1654, his holinefs refigned himfelf entirely into the hands of this affuming woman j Avho, obferving his infirmities daily increafing, redoubled her rapacity", difpofing of benefices to the higheft bidders in all parts of Italv. She Avas again, however, in hazard of being difplaced by a nevv fav’ourite, viz. the cardinal de Retz j and had not the pope’s diffolution prevented it, it Avould in all probability quickly have taken place. During his laft illnefs he received nothing but from the hands of Donna Olympia, who Avas at great pains to prolong his life, Avatched continually at his bed fide, and pre¬ vented the ambafladors or others from difturbing him Avith difeourfes upon bufinefs. She is faid, during the laft ten days of his life, when he continued without the ufe of reafon, to have amaffed about half a million of crowns. She did not find the fuccecding pope (Alex¬ ander VII.) fo eafy to be played upon as his Aveak pre- deceffor: a number of memorials were fent in againft her, and his holinefs Avas Avell difpofed to attend to them : he ordered her to retire from Rome, and at the fame time began to examine Avitneffes refpefting her conduft. She Avas cut off, hoAvever, before the trial was finifhed, by the plague, Avhich, in 1636, affii£!ed Rome and its neighbourhood. Her eftate was not con- fifeated as Avas generally expefted j and the prince Pamphilio Avas allowed to fucceed her. The pope only referved for his own relations about a million of croAvns. Olympia, in Ancient Geography, Avith the furname Pifatis (Strabo) \ fo called from the territory of Pifain Elis j deferibed by Strabo', “ as the temple of Jupiter Olympius, before which Hands a grove of wild olive trees, in which is the ftadium, or foot-courfe, fo called becaufe the eighth part of a mile •, and by Avhich the Alpheus, coming doAvn from Arcadia, runs.” Olym¬ pia, however, was famous not merely for the temple of Jupiter, but alfo for a temple of Juno, 63 feet long, writh columns round it of the Doric order j and a Metroum or temple of the mother of the gods, a large Doric edifice ; with holy treafuries. Thefe, and the porticoes, a gymnafium, prytancum, and many more buildings, chiefly in the enclofure, Avith the houfes of the priefts and other inhabitants, made Olympia no in- confiderable place. The ftadium was in the grove of Avild olive trees, before the great temple 5 and near it was the hippodrome or courfe fi r the races of horfcS and chariots. The Alpheus flowed by from Arcadia with a copious and very pleafant ftream, which Avas re¬ ceived on the coaft by the Sicilian fea. The temple of Jupiter Avas of the Doric order, 68 feet high to the pediment, 95 Avide, and 230 long-, the cell encompaffed with columns. It Avas erefled Avith the country ftone the roof not of earth baked, but of Pentelic marble \ the flabs difpoftd as tiles ; the way to it up a AVinding ftaircafe. The two pediments Averc enriched with fculpture and one had over the centre a flatue of Viclory gilded 5 and underneath a votive buckler of gold. At each corner was a gilded srafe. Above the columns Avere fixed 21 gilded bucklers, of¬ fered at the conclufion of the Achaean Avar by the Ro¬ man general Mummius. The gates in the tAvo fronts O L Y [I Olympia, ■yyere ofbrafs, and over them were carved the labours of Olympiad. ££ertu]e9. Within the ceil were double colonnades, be- y tween which -was the approach to the image. The Jupiter of Olympia was accounted alone fuffi- cient to immortalize its maker, Phidias. It was of ivory and gold, the head crowned with olive. In the right hand was a ftatue of Vidlory; in the left a flowered fceptre, compofed of various metals, on which ■was an eagle. The fandals were of gold, as alio the veilment, which was curioufly emboffed with lilies and animals. The throne was gold inlaid with ebony and ivory, and ftudded with jewels, intermixed with paint- , ings and exquifite figures in relievo. The pillars be¬ tween the feet contributed to its fupport. Before it were walls, ferving as a fence, decorated principally with the exploits of Hercules; the portion oppolite to the door of a blue colour. It was the office of a fa¬ mily defcended from Phidias, called phadruntce or the poli/hersy to keep the work bright and clean. The Veil or curtain was cloth rich with the purple dye of Phoenicia and with AlTyrian embroidery, an offering of King Antiochus, and was let down from above by loofening the firings. The image impreffed on the fpec- tator an opinion that it was higher and wider than it meafured. Its magnitude is fuch, that though the tem¬ ple was very large, the artift feemed to have erred in the proportions. The god, fitting, nearly touched the ceil¬ ing with his head 5 fuggefting an idea, that if he were to rife up, he would deftroy the roof. A part of the pavement before it was of black marble, enclofed in a rim of Parian or white, where they poured oil to pre- forve the ivory. The altar of Jupiter Olympius was of great antiqui¬ ty, and compofed of allies from the thighs of the vic¬ tims, which were carried up and confumed on the top with wood of the white poplar tree. The allies alfo of the prytaneum, in which a perpetual fire was kept on a hearth, were removed annually on a fixed day, and ipread on it, being firff mingled with water from the Alpheus. The cement, it was affirmed, could be made with that fluid only j and therefore this river was much refpe£led, and effeemed the moft friendly of any to the god. On each fide of the altar were Hone fleps. I ts height was 22 feet. Girls and women, when allowed to be at Olympia, were fuffered to afeend the bale- ment, which was 125 feet in circumference. The peo¬ ple of Elis facrificed daily, and private perfons as often as they chofe. Religion flouriffied at Olympia, and many deities were worlhipped befides Jupiter. Paufanias has enumerated above 60 altars of various ffiapes and kinds. One of the unknown gods flood by the great altar. The people of Elis offered on all thefe monthly ; laying on them boughs of olive •, burning incenfe, and wheat mixed with honey ; and pouring libations of fuch liquors as the ritual preferibed. At the latter ceremony fometimes a form of prayer was ufed, and they lung hymns compofed in the Doric dialed;. Olympia was fituated on an eminence, between twro mountains called Oj/ii and Olympus. Though its ancient Iplendour is gone, the place reminds the traveller of w hat it once was. It is in the Morea, being npwr a fmall place called Longinico, 50 miles fquth of Lepanto, in E. Long. 22. o. N. Eat. 37. qo. O-eA MPIAD, the fpace of four years, whereby 2 35 1 O L Y the Greeks reckoned time.—1 he firft Olympiad fell, 'Olympiad according to the accurate and learned computation of II Erne of the moderns, exadly 776 years before the firff °,lyrapic year of Chrift, or 775 before the year of his birth, in . , the year of the Julian period 3938, and 22 years before the building of the city of Rome, he games were exhibited at the time of the full moon next after the fummer folftiee 5 therefore the Olympiads were of un¬ equal length, becauie the time of the full moon differs 11 days every year, and for that icalon they fometimes began the next day after the folitice, and at other times four weeks after. Tho computation by Olympiads ceafed, as fome iuppole, alter the 304th, in the year 440 of the Chriffian era. It was univerfally adopted not only by the Greeks, but by many of the neighbouring countries j though ffill the Pythian games ferved as an epoch to the people of Delphi and to the Boeotians; the Nemaean games to the Argives and Arcadians ; and the Ilihmian to the Corinthians and the inhabitants of the Peloponnefian ifthmus. To the Olympiads hilfory is much indebted, i hey htave ferved to fix the time of many momentous events : and indeed before this method of computing time was obierved, every page of hiiiory is moftiy fabulous, and filled with obfeurity and contra¬ diction, and no true chronological account can be pro¬ perly eftabliffied and maintained with certainty. OLYMPIAS, a celebrated woman, who was daugh¬ ter of a king of Epirus, and who married Philip king of Macedonia, by whom the had Alexander the Great. Her haughtinefs, and more probably her infidelity, obli¬ ged Philip to repudiate her, and to marry Cleopatra, the niece of King At talus. Olympias was fenfible of this injury, and Alexander fhowed his difapprobation of his father’s meafures, by retiring from the court to his mother. The murder of Philip, which foon followed this difgrace, and w hich fome have attributed to the in¬ trigues of Olympias, was produdfive of the greater! ex¬ travagances. Ihe queen paid the greateft honour to her hufband’s murderer. She gathered his mangled limbs, placed a crown of gold on his head, and laid his allies near thofe of Philip. The adminiftration of Alex¬ ander, who had fucceeded his father, was in fome infian¬ ces offenffve to Olympias ; but when the ambition of her fon was concerned, fhe did not fcruple to declare publicly that Alexander wras not the fon of Philip, but that he was the offspring of an enormous ferpent who had furpernaturally introduced himfelf into her bed W hen Alexander was dead, Olympias feized the government of Macedonia; and, to effablilh her ufurpation, fhe cruelly put to death Aridmus, with his wife Eurydice, as alfo Nicanor the brother of Caflander, with 100 lead¬ ing men of Macedon, w ho were inimical to her intereft. Such barbarities did not long remain unpunifhed: Caf- fander befieged her in Pydna, where fhe had retired with the remains of her family, and flie was obliged to fur- * render after an obftinate liege. The conqueror ordered her to be accufed, and to be put to death. A body oi 200 fnldiers were ordered to put the bloody commands into execution, but the Iplendour and majefly of the queen difarmed their courage ; and flie was at laft maf- facred by thofe whom ihe had cruelly deprived of tiieir children, about 316 years before the Chriftian era. GL\ MP1C games, were folemn games among the ancient Greeks, fo called from Olympian Jupiter, to whom they were dedicated; and by fome faid to be fir it Olympic Games. ° L Y [136 ] firfl; inftituted by him, after his vi&ory over the Ions of antiquity . Titan ; others afcribe their inftitution to Hercules, not O L Y * Gillies's Hijlory of Greece* the fon of Alcmena, but one of much greater antiqui ty j others to Pelops; and others to Hercules the fon of Alcmena. By whomfoever they were inilituted, we know that, at a period rather early, they had fallen into difufe. The wars which prevailed among the Greeks, for a while, totally interrupted the religious ceremonies and exhibitions with which they had been accuilomed to honour the common gods and heroes; but the Olympic games were reftored on the following occafion. Amidft the calamities which affli£led or threatened Peloponnefus, Iphitus, a defcendant of Oxylus, to whom the province of Eleia * had fallen in the general partition of the pen- infula, applied to the Delphic oracle. The priefls of Apollo, ever difpofed to favour the views of kings and legillators, anfwered agreeably to his wilh, that the fe- ftivals anciently celebrated at Olympia, on the Alpheus, muff be renewed, and an armitf ice proclaimed for all the Hates willing to partake of them, and delirous to avert the vengeance of heaven. Fortified by this authority, and aflifted by the advice of Lycurgus, Iphitus took meafures, not only for retioring the Olympic folemnity, but for rendering it perpetual. The injunftion of the oracle wras fpeedily diffufed through the remoteft parts of Greece by the numerous votaries who frequented the facred fhrine. The armilfice was proclaimed in Pelo¬ ponnefus, and preparations were made in Eleia for ex¬ hibiting (hows and performing facrifices. In the heroic ages, feats of bodily ftrength and addrefs Were deftined to the honour of deceafed warriors; hymns and facrifices were referved for the gods : but the flexible texture of Grecian fuperftition, eafily confounding the expreffions of refpe&ful gratitude and pious veneration, enabled Iphitus to unite both in his new inftitution. The feftival, which lafted five days, began and end¬ ed with a facrifice to Olympian Jove. The intermediate time was chiefly filled up by the gymnailic exercifes, in which all freemen of Grecian extraftion were invited to contend, provided they had been born in lawful wed¬ lock, and had lived untainted by any infamous irtimoral ftain. The preparation for this part of the entertain¬ ment was made in the gymnafium of Elis, a fpacious edifice, furrounded by a double range of pillars, with an open area in the middle. Adjoining were various apart¬ ments, containing baths, and other conveniences for the combatants. The neighbouring country was gradually adorned with porticoes, fliady walks and groves, inter- fperfed with feats and benches ; the whole originally deftined to relieve the fatigues and anxiety of the can¬ didates for Olympic fame; and frequented in later times, by fophifts and philofophers, who were fond to contemplate wifdom, and communicate knowledge, in thofe delightful retreats. The order of the athletic exercifes, or combats, was eftabliihed by Lvcurgus, and correfponded almoft exaftly to that defcribed by Ho¬ mer, in the 23d book of the Iliad, and eighth of the Odyffey. Iphitus, we are told, appointed the other ce¬ remonies and entertainments ; fettled the regular return of the feftival at the end of every fourth year, in the month of July ; and gave to the whole folemnity that form and arrangement, which it preferved with little va¬ riation above a thoufand years; a period exceeding the duration of the moft famous kingdoms and republics of Among the benefaflors of Olympia, at a much later period, was reckoned Herod, who was after- wards king of Judsea. Seeing, on his way to Rome, the games neglefted or dwindling into inlignificance from the poverty of the Eleans, he difplayed vaft muni¬ ficence as prefident, and provided an ample revenue for their future fupport and dignity. The care and management of the Olympics belong¬ ed for the moft part to the Eleans ; who on that account enjoyed their pofieffisns without moleftation, or fear of war or violence. They appointed a certain number of judges, who were to take care that thofe who offered themfelves as competitors fhould perform their prepara¬ tory exercifes ; and thefe judges, during the folemnity, fat naked, having before them a crown of vitiory, form¬ ed of wild olive, which was prefented to whomloever they adjudged it. Thofe who were conquerors w'ere called Ohjmpionices, and were loaded with honours by their countrymen. At thefe games women were not allowed to be prefent; and if any woman was found, during the folemnity, to have paffed the river Alpheus, the was to be thrown headlong from a rock. This, however, was fometimes neglected ; for we find not on¬ ly women prefent at the celebration, but alfo fome among the combatants, and fome rewarded with the crown. The preparations for thefe feftivals were great. No perfon was permitted to enter the lifts, if he had not re¬ gularly exercifed himfelf ten months before the celebra¬ tion at the public gymnafium of Elis. No unfair deal¬ ings wTere allow'ed; whoever attempted to bribe his ad- verfary wras fubjefled to a fevere fine ; and even the fa¬ ther and relations were obliged to fwear that they would have recourfe to no artifice which might decide the vic¬ tory in favour of their friends. No criminals, norfuch as were connefted with impious and guilty perfons, were fuffered to prefent themfelves as combatants. The wreftlers were appointed by lot. Some little balls fu- perfcribed with a letter w'ere thrown into a filver urn, and fuch as drew the fame letter were obliged to contend one with the other. He who had an odd letter remain¬ ed the laft ; and he often had the advantage, as he was to encounter the laft who had obtained the fuperiority over his adverfary. In thefe games were exhibited run¬ ning, leaping, wreftling, boxing, and the throwing of the quoit, which was called altogether mvTctShev, or qinn- quertiunu Befides thefe, there were horfe and chariot races, and alfo contentions in poetry, eloquence, and the fine arts. The only reward that the conqueror obtained was a crown of olive. This, as fome fuppofe, was in memory of the labours of Hercules, which were accom- plifhed for the univerfal good of mankind, and for which the hero claimed no other reward but the confcioufnefs of having been the friend of mankind. So fimall and trifling a reward ftimulated courage and virtue,and wasthefource of greater honours than the moft unbounded treafures. The ftatues of the conquerors, called Ohjmpionicce, were erefted at Olympia in the facred wood of Jupiter. Their return home was that of a warlike conqueror ; they were drawn in a chariot by four horles, and every where received with the greateft acclamations. Their entrance into their native city was not through the gates : to make it more grand and more folemn, a breach was made in the walls. Painters and poets were employed in celebrating their names ; and indeed the victories Olympic Games. I O L Y [ I Olympic, victories feverally obtained at Olympia are tire fuhje&s _ Olyopm- ^ of the molt beautiful odes of Pindar. The combatants v "' were naked. A fcarf was origirtally tied round their waiit; but when it had entangled one of the adverfa- ries, and been the caufe that he loft the victory, it was laid afide, and no regard was paid to decency. The Olympic games were obferved every fifth year, or, to fpeak with greater exaftnefs, after a revolution of four years, and in the firft month of the fifth year, and they continued for five fucceflive days. As they were the moft ancient and moft folemn of all the feftivals of the Greeks, it will not appear wonderful that they drew fo many people, not only inhabitants of Greece, but of the neighbouring iflands and countries. Such is the account of Grecian writers, who have, doubtlefs, often afcribed to pofitive inftitutian many in¬ ventions and ufages naturally refulting from the progref- five manners of fociety. When we come to examine the Elean games in. their more improved ftate, together with the innumerable imitations of them in other pro¬ vinces of Greece, there will occur reafons for believing, that many regulations, referred by an eafy folution to the legillative wifdom of Iphitus or Lycurgus, were in¬ troduced by time or accident, continued through cuftom, improved by repeated trials, and confirmed by a fenfe of *H?!lore’'f t^K‘r utility *• an hrftitution as the Olympi- Greece. ac'> even 'n *ts perfeft form, muft have been attend¬ ed with manifeft advantages to fociety. It is fufficient barely to mention the fulpenfion of hoftilities which took place, not only during the celebration of the fefti- val, but a conuderable time both before and after it. Confidered as a religious ceremony, at which the whole Grecian name was invited, and even enjoined to aftift, it was well adapted to facilitate intercourfe, to promote knowledge, to (often prejudice, and to haften the pro- grefs of civilization and humanity. Greece, and parti¬ cularly Peloponnefus, avas the centre from which the ad¬ venturous fpirit of its inhabitants had diffufed innumer¬ able colonies through the furrounding nations. To thefe widely feparated communities, which, notwith- ftanding their common origin, feemed to have loft all connexion and correfpondence, the Olympiad ferved as a common bond of alliance and point of re-union. The celebrity of this feftival continually attracted to it the characters moft diftinguilbed for genius and enterprife, whofe fame would have otherwife been unknown and loft in the boundlefs extent of Grecian territory. The remote inhabitants, not only of European Greece, but of Afia and Africa, being aflembled to the worfinp of common gods, were formed to the fenfe of a general intereft, and excited to the purfuit of national honour and profperity. Strangers of fimilar difpofitions might confirm in Elis the facred and indifloluble ties of hofpi- tality. If their communities were endangered by any barbarous power, they might here folicit afli lance from their Grecian brethren. On other occafions they might explain the benefits which, in peace or war, their refpec- tives countries were beft qualified to communicate. And the Olympic feftival might thus ferve the purpofe of refident atnbafladors, and other inftitutions alike un¬ known to antiquity. OLYMPUS, the name of feveral mountains.—One bounding B’.thynia on the fouth.—Another in the illami of Cyprus, on whofe top was a temple of Venus, which women were not permitted either to enter or to VOL. XV. Part I. 37 ] O M A fee (Strabo).—A third, Olympus of Galatia (Livy). Olympus —A fourth, of Lycia, with a noble cognominal town, il near the fea coaft (Strabo, Cicero), extxnCt in Pliny’s 0mar~ , time, there remaining only a citadel \ the town was de- v ftroyed by P. Servilius Ifauricus (Floras), having been the retreat of pirates. From this mountain there was an extenfive profpeCl of Lycia, Pamphilia, and Pifidia (Strabo).-—A fifth, Olympus of Myfia (Ptolemy); thence furnamed Olympena, anciently Minor; one of the higheft mountains, and furnamed Mysius (Theo- phraftus ;) (ituated on the Propontis, and thence extend¬ ing more inland.—A fixth,on the north of Theffaly, or on the confines of Macedonia ; famous for the fable of the giants (Virgil, Horace, Seneca); reckoned the higheft in the whole world, and to exceed the (light of birds (Apuleius), which is thereafon of its being called heaven, than which nothing is higher : the ferenity and calmnefs which reign there are celebrated by Homer, * Lucan, and Claudian. OLYRA, a genus of plants belonging to the mo- ncecia clafs; and in the natural method ranking under the 4th order, Gramina. See Botany Index. OMAR Ebn Al Khattab, fucceffor of Abu Beer. —The Mohammedan impofture, like every other falfe- hood of its kind, copies after the truth as far as was thought convenient or proper; and miracles being the grand proof of revelation, it was to be expefted that all pretences to that (hould aftume at leaft the ap¬ pearances of them. Few fyftems of faith are more abfurd than Mohammed’s; yet, thouglx he difelaimed miracles, it was fupported, as we are told by latter wri¬ ters, by a variety of them, which, however, unfortunate¬ ly for the creed they were contrived to fupport, are too tritling, abfurd, and contradictory, to deferve the fmall- eft attention. They tell us, but upon grounds too vague and in¬ determinate to command belief, that Omar was mira- euloufly converted to this faith : a man he is report¬ ed to. have been, before this event, truly relpedtable, and in particular a violent oppofer of the Arabian prophet. Mohammed, it feems, felt this oppofition, and regretted it ; he therefore, with the fervour, and as it happened, with the fuccefs of a true prophet, ac¬ cording to his followers account, prayed for the conver- fion of this his dangerous antagonift. Omar, it is faid, had no fooner read the 20th chapter of the Koran than he was convinced : upon which he inftantly repaired *to Mohammed and his followers, and declared his conver- fion. It is (aid, that at one time he intended to murder the prophet; and various caufes are afligned for the prevention of this (hocking piece of facrilege. After his wonderful converfion, the Mohammedan writers inform us that he was furnamed Al Faruk, or the “ divider;” beeaufe, fay they, when a certain Modem was condemned by Mohammed for his iniquitous treat¬ ment of a Jew, and appealed afterwards from the fen- tence of the prophet to Omar, he cut him in two with his feimitar for not acquiefcing in the deciuon of fo upright a judge: which circumftance when Mohammed heard, he gave him the furname of Al Faruk, or “ the dividerbecaufe, by this a&ion, he had (hown himfelf capable of perfectly diftinguhh- ing between truth and falfehood. Al Kodai affirms, that 39 of Omar’s adherents followed his example the fame day he profeffed himfelf a votary of Mohammed, S The O M A [ 13B ] O M B The eonverfion of Hamza and Omar Ebn A1 Khattab happened in the year preceding the firfl: flight of the Modems into Ethiopia, or the fourth year of Moham¬ med’s midion, according to Abulfeda. Pie was un- queftionably a great acquifltion to the prophet, and enabled him to carry on his fchemes to far more pur- pofe than lie could poflibly have done without him, or if he had continued his enemy. Omar at length found his fervices in the caufe he had undertaken luf- ficiently honoured and amply rewarded ; for on the death of Abu Beer, who had fucceeded the impoftor himfelf, he wras promoted to the regal and pontifical dignity. The title firft afligned him was the caliph of the. caliph of the apoflle of God; or in other words the fuccefl'or of the fucceffor of Mohammed: but the Arabs coniidering that this title, by the addition to be an¬ nexed to it at the acceflion of every future caliph, would be too long, they, by univerfal confent, fa- luted him the emperor of the believers ; which illuftrious title, at this junclure conferred on Omar, defeended afterwards to all the fucceflbrs of that prince. Our readers will not expeft us to follow the caliph with minute exadlnefs through the tranfadlions of his reign. This w’ould indeed fwell our article beyond all propor¬ tion. We {hall therefore confine ourfelves to forne of the leading fads. His arms appear to have been particularly fuccefs- ful ; the Perfians he conquered, and Jerufalem fub- mitted to his power •, nor does he appear to have been checked in a Angle inftance. In confequence, however, of his fuccefs, an attempt was made to affaflinate him.' The fad is thus related : Wathek Ebn Mofafer, a re- lolute young Arab, was procured by the king of Ghaf- fan, and fent to Medina for this very purpofe. Some time after his arrival, obferving Omar to fall afleep under a tree on which he had placed himfelf, fo as not to be difeovered by any perfon, he drew' his dag¬ ger, and was upon the point of ftabbing him, when, lifting up his eyes, he faw a lion walking round about him, and licking his feet. Nor did the lion ceafe to guard the caliph till he awoke ; but then inftantly wrent awray. This phenomenon {truck Wathek with a pro¬ found reverence for Omar, whom he now revered as the peculiar care of heaven. He therefore came down from the tree, on which the lion had forced him to remain, kiffed the caliph’s hand, confelfed his crime, and em¬ braced the Mohammedan religion ; being fo ftrongly affedted with the wTonderful deliverance he had been an eye witnefs of. His life, however, was at length ended by affaflination •, for about two years after the conclulion of the Nohawandian war, in which the Arabs probably {till farther extended their conquefts, though no account of their military operations during that pe¬ riod has reached us, that is in the 23d year of the He¬ gira, according to Abu Jaafar A1 Tabari, the caliph o mar Ebn A1 Khattab was affaflinated by a Perfian flave ; of which horrid fadt the Arab writers have hand¬ ed down the following particulars : Abu Lulua, a Per- lian of the Magian fedt, whofe name was Tiru%, one of A1 Mogheira Ebn A1 Shaabah’s flaves, was obliged by his mafter to pay daily two dirhems, in conformity to the Mohammedan cuftom, for the free exercife of this religion. Firuz relenting this treatment, complained of it to the caliph, and defired that fome part at leail of the tribute exadted of him might be remitted j but this favour being refufed by Omar, the Perfian threatened Omar, his deftrudlion j which he foon after effedfed, by itab- Ombi. bing him thrice in the belly with a dagger, while he v”'" was in the mofque at Medina performing his morning devotions. The Arabs then prefent perceiving that the villain had imbrued his hands in the blood of their fove- reign, immediately rufhed upon him j but he made fo defperate a defence, that he wounded 13 of the affailants, and feven of them mortally. At laft one of the caliph’s attendants threw his veil over him, and feized him ; up¬ on which he llabbed himfelf and foon after expired. According to Theophanes, this Firuz was an apollate or renegade, and confequently had before embraced the Mohammedan religion : but this aflertion is by no means probable j becaufe on his becoming a convert to Iflamifm, he muft have been manumitted by his mafter, and on his relapfinginto Magiifm, he would have been put to death by the caliph’s order : neither of which particulars are confident with what we find related by the Arab hifto- rians, and even by our Greek chronographer himfelf. Omar languished three days and then died, in the month of Dhu’lhajja, and the 23d year of the Hegira, which began in the year of our Lord 64,3. Authors are net agreed with regard to the duration of his caliphate. The Arab hiftorians, whom we are inclined to follow, fay that he reigned between 10 and 11 years. Theo¬ phanes affirms, that he was murdered in the 1 2th year of his caliphate, and Dionyfius Telmarenfis extends the length of his reign to 12 complete years. Only one of the wounds given him by Firuz was mortal, and that he received under his navel. At his death he w as 63 years old; which, as we are told by an Arab author, was the age of Mohammed himfelf, Abu Beer, and Ayeftia, one of the prophet’s waves, when they died. "When Omar fell in the mofque, Abd’alrahman Ebn Awf, one of Mohammed’s firft converts, fupplied his place during the remainder of the ferviee j and three days be¬ fore his death, Sahib Ebn Tarfib, at his command, offi¬ ciated for him. His body was interred in Ayelha’s apartment, near that of the prophet Mohammed. We are informed by Eutychius, that during his caliphate he performed the pilgrimage to Mecca nine times. His ex- tenfive conquefts made the Moflem empire one of the moft powerful and formidable monarchies in the wmrld. His difpofition is reprefented to us, with evident par¬ tiality indeed, as one of the beft poflible, and his tempe¬ rance has always been highly extolled. OMBI, a city of ancient Egypt, afterwards called Arfvioe and Crocodilopo/is, was the capital of one of the nomes into which that country was divided, and is re¬ markable, in the annals of idolatry, for the hatred of its inhabitants to the religion of their neighbours the citizens of Tentyra. The genius of paganifm was fo complying with re- fpedl to the objefts of religious worlhip, that although each nation, each city, and almoft every family, had its own tutelar god, we know not a fingle inftance, out of Egypt, of one tribe of Pagans perfecuting another for w'orftripping gods different from theirs. The Jews and Chriftians w7ere indeed perfecuted by the Romans, not however for worftripping the true God, but becaufe, to¬ gether with him, they would not vorfhip Jupiter, Juno, and all the rabble of heathen divinities. The reafon of the almoft univerlal tolerance of ido¬ laters to one another, and of the intolerance of all to the Ornl/i, Ombre. « Prep. Lvan%. p. 32. Steph. ed. O M B [I the Jews and Chridians, is very obvious. Not a fingle Pagan, a very few philofophers perhaps excepted, ever thought of paying his adoration to the Supreme and felf-exiftent Being, but to inferior divinities, to whom it was fuppofed that the care of particular perfons, fami¬ lies, cities, and nations, was configned by the God of the univerfe. The confequence was, that, as no perfon denied the divinity of his neighbour’s objeft of wor- fliip, an intercommunity of gods was everywhere ad¬ mitted, and all joined occafionally in adoring the gods of the various nations. By the Jews and Chriftians this communion was rejeftcd as in the higheit degree impious ; and it could not well be maintained between the citizens of Ombi and thofe of Tentyra. That brutes were worthlpped in Egypt is univerfally known (fee Polytheism) ; and Diodorus the Sicilian informs us, in a paffage quoted by Eufebius*, that “the cities and nomes of Egypt being at one time prone to rebellion, and to enter into confpiracies againft monar¬ chical government, one of their moft politic kings con¬ trived to introduce into the neighbouring nomes the worfhip of different animals-, fo that while each reve¬ renced the deity which itfelf held facred, and defpifed that which its neighbours had eonfecrated, they could hardly be brought to join cordially in one common de- fign to the difturbance of the government.” In this diftribution of gods he conferred upon Ombi the crocodile, and upon Tentyra, the mortal enemy of that monfter, the ichneumon. T he confequence of which was, that while the Ombites worfhipped the crocodile, the Tentyrites took every opportunity of flaughtering him, infomuch that, according to Strabo, the very voice of an inhabitant of Tentyra put the crocodile to flight. Ehis, we confefs, is a very improbable fatt but it is certain that the mutual hatred of thofe cities, on ac- ' count of their hoftile gods, rofe to fuch a height, that whenever the inhabitants of the one were engaged in the more folemn rites of their religion, thofe of* the o- ther Avere fure to embrace the opportunity of fetting fire to their houfes, and rendering them every injury in their poAver to inflift. And Avhat may, to afuperficial thinker, appear extraordinary, though it Avill excite no wonder in the bread: of him Avho has ftudied mankind, this animofity continued betAveen the inhabitants of the tAvo cities long after the crocodile and ichneumon had loft their divinity. 1 he conduct of the Egyptian monarch Avas admi¬ rably calculated for preventing the nation from com¬ bining againft the government; and it extended its influence over the Avhole kingdom. Diodorus informs us» that he affigned to each nome an animal to Avor- fhip, which Avas hated, killed, and fometimes fed up¬ on by the inhabitants of the neighbouring nome and we knoAV, upon higher authority than his, that the Ifraelites could not offer facrifices in Egypt, becaufe the bullock Avas deemed facred over the whole coun¬ try. OMBRE, a celebrated game at cards, borrowed from the Spaniards, and played by tivo, by three, or by five perfons, but generally by three. When three play at this game, nine cards are dealt to each party j the whole ombre pack being only 40 : becaufe the eights, nines, and tens, are throAvn out of the pack. J here are two forts of counters for flakes, the greater 39 ] OMB and the Idler j the laft having the fame proportion to Otnbrf. the other as a penny to a ftiilling : of the greater coun- 1 tens each man flakes one for the game j and one of the Idler for palling for the hand, when eldeft, and for every card taken in. . As to the order and value of the cards, tire ace of fpades, called fpadi/lo, is alrvays the higheft trump, in Avhatfoever fuit the trump be ; the manille, or black duce, is the fecond ; and the bajlo, or ace of duos, is alrvays the third : the next in order is the king, the queen, the knave, the hwen, the fix, the five, four, and three. Of the black there are 11 trumps ; of the red, j 2. The leaft fmall cards of the red are always the belt, and the moft of the black j except the duce andredfeven, both of Avhich are called the manilles, and are always fecond when the red is a trump. The red ace, Avhen a trump, enters into the fourth place, and is called puiito ; otherAvife it is only called an ace. The three principal cards are called mat adores ; Avhieh have this privilege, that they are not obliged to attend an inferior trump Avhen it leads ; but foi want of a fmall trump, the perfon may renounce trumps, and play any other card j and Avhen thefe are all in the fame hand, the others pay three of the great- ei counters a-piece 5 and Avith tnefe three for a foun dation, he may count as many matadores as he has cards in an uninterrupted feries of trumps; for all Avhich the others are to pay one counter a-piece. He who hath the firft hand is called ombre, and has his choice of playing the game, of naming the trump, and of ta- king in as many and as few cards as he pleafes ; and after him the fecond, &c. But if he does not name the trump before he looks on the cards he has taken in, any other may prevent him, by naming what trump he pleafes. He that has the firft hand ftiould neither take in, nor play, unlefs he has at leaft three fure tricks in his hand : for, as he Avins the game who wins moft tricks, he that can Avin five of the nine has a fure game r Avhich is alfo the cafe if he Avins four, and can fo divide the tricks as that one perfon may Avln twro, and the other three. If a perfon play without difearding or changing any cards, this is called playing fans prendre ; and if another Avin more tricks than he, he is faid to win co~ dille. The over-fights in the courfe of the game are called bea/ls. And if the ombre Avins all the nine tricks, it is called winning the vole. In ombre by five, which many, on account of its not requiring fo clofe an attention, prefer to that by three, only eight cards a-piece are dealt; and five tricks muft be won, otherwife the ombre is beafted. Here the per- lon who undertakes the game, after naming the trump, calls a king to his afliftance; upon which the perfon in xvliofc hand the king is, without difeovering himfelf, is to aflift him as a partner, and to fliare his fate. If, between both, they can make five tricks, the ombre Avins tivo counters, and the auxiliary king only one ; but a. hen the counters are even, they divide them equally. If the ombre venture the game without calling in any king, this too is called playing fans prendre ; in Avhich cafe the other four are all againft him, and he muft win five trices alone, or be beafted. The reft is much the fame as by three. OMBRE defoleil, “ Shadow of the fun,” in Herald- ry, is when the fun is borne in armory, fo as that the S 2 eves. O M E [ 140 ] O M E Ombre eyes, nofe, and mouth, which at other times arc repre- II fented, do not appear 5 and the colouring is thin, fo 0nieri‘ that the field can appear through it. ’“_v ^ OMBRI A, the ancient name of a province of Italy, in the territory of the pope, now called Spoletto and Perugia. OMBRO, or Lombro, a town of Italy, in the duchy of Tufcany, and territory of the Siennois, fituated near the Tufcan fea, a little fouth of the lake of Cafliglione, 45 miles fouth-weft of Sienna. OMBROMETER, an inftrument to meafure the quantity of rain that falls. We have the defcription and figure of one in Phil. 1 ranf. Is0 473; P‘ l2, ^ confifts of a tin funnel, whofe furface is an inch fquare, with a flat board, and a glafs tube fet into the middle, of it in a groove. 1 he rile of the water in the tube, whofe capacity at different times muft be meafured and marked, (hows the quantity of rain that has fallen. OMELET, or Amlet, a kind of pancake or fri- catlee of eggs, with other ingredients, very ufual in Spain and France. It may be made as follows. 1 he eggs being beaten, are to be feafoned with fait and pepper, and then fried in butter made boiling hot-, this done, gravy is to be poured on, and the whole ftewed with chives and parfley Aired fmall : when one fide is fried enough, it is to be turned on the other. OMEN, is a word which, in its proper fenfe, figni- fies a fign or indication of fome future event, taken from the language of a perfon fpeaking without any intent to prophecy. Hence Tully fays, “ Pythagorei non folum voces deorum obfervarunt, fed etiam hominum, quae vo- cent omina “ the Pythagoreans attend to the difeourfe not only of gods, but alfo of men, which they call omens.” This fort of omen was fuppofed to depend much upon the will of the perfon concerned in the event 5 whence the phrafes accepit omen, arripuit omen. Such were the ori¬ ginal omens ; but they wTere afterwards dei iv ed from things as well as from words. 1 hus Paterculus, ipeaking of the head of Sulpicius on the roftrum, fays it was vejut omen imminentfs profcriptlonis, “ the omen of an im¬ pending profeription.” Suetonius fays of Auguftus, that he believed implicitly in certain omens; and that, ft mane fibi calceus perperam, acfinijler pro dextero mdu- ceretur ut dirum, “ If his ftioes were improperly put on in the morning, efpecially if the left flioe was put upon his right foot, he held it for a bad omen.” Omen was ufed in a ftill larger fenfe, to fignify an augury; as in the following line of fully. “ Sic aquilm clarum fir- mavit Jupiter omen “ thus Jove confirmed the bright Omen, omen of the eagle.” It was lafily ufed, in the moft ''——v— generic fenfe of all, for a portent or prodigy j as in the third book of the TEneid, where a myrtle torn up by Hineas dropped blood. Upon this appearance, fays the herd, — Mihi frigidus horror Membra quatit, gelidufque coit formidine fanguis. And the fame thing being repeated upon his breaking a branch from another tree, he prayed to the gods to avert the omen. Malta movens animo Nymphas venerabar agreftes, Gradivumque patrem, Geticis qui pnefidet arvis, Rite fecundarent vifus, owewque levarent (a). The portentous or fupernatural omens were either external or internal. Of the former fort were thole fliowers of blood fo frequently occurring in the Roman hiftory, which were much of the fame nature with this adventure of Aineas, which he calls monstra drum. Of the fecond fort were thofe fudden confternations, which, feizing upon men without any vifible caufe, were imputed to the agency of the god Pan, and hence called panic fears. But indeed there w7as hardly any thing, however trivial, from which the ancients did not draw omens. That it fliould have been thought a direful omen when any thing befel the temples, altars, or ilatues of the GODS, need excite no wonder 5 but that the meeting of a eunuch, a negro, a bitch with whelps, or a fnake lying in the road, Ihould have been looked upon as portending bad fortune, is a deplorable infiance of human weaknefs, and of the pernicious in¬ fluence of fuperftitioH on the mind. It is more than probable that this praflice of making ordinary events ominous of good or bad fortune took its rife in Egypt, the parent country of almsft every fuper- ffition of paganifm j but wherever it may have arifen, it fpread itfelf over the whole inhabited globe, and at this day prevails in a greater or lefs degree among the vulgar of all nations. In England, it is reckoned a good omen, or a fign of future happinefs, if the fun fliines on a couple com¬ ing out of the church after having been married. It is alfo efteemed a good fign if it rains whilft a corpfe is burying : Happy is the bride that the fun {hines on; Happy is the corpfe that the rain rains on. To f A-) Inftead of tranlkti™ thofe flwrt quotations, sve flail here give Dryden’s verfion of the whole of this portentous adventure, as tve are perfuaded that the mere Englifl. reader who tdone. can w,(h for a tranflaUon, will be glad to have the fulleft account of the bleeding myrtle, together with its effeas on the mind of hero. glad It is as follows: Not far, a rifing hillock flood in view $ Sharp myrtles on the Tides and corners grew. There, while I went to crop the fylvan feenes, And (hade our altar with their leafy greens, I pull’d a plant (with horror I relate A prodigy fo firange, and full of fate) : The rooted fibres rofe 5 and from the wound Black bloody drops diftill’d upon the ground. Mute and amaz’d, my hair with terror flood ^ Fear fhrunk my finews, and congeal’d my blood. Mann’d once again, another plant I try ; That other gufli’d with the fame fanguine dye. Then, fearing guilt for fome offence, unknown, AFith prayers and vows the Dryads I atone, With all the filters of the woods, and moft The god of arms, who rules the Thracian craft: That they, or he, thefe omens would avert, Releafe our fears, and better ligns impart. 4 O M E [ i Omen. To break a looking glafs is extremely unlucky ; the party to whom it belongs will lofe his bell friend. ^ if, going a journey on bufinefs, a fow crofs the road, you will probably meet with a difappointment, if not a bodily accident, before you return home. To avert this you mull endeavour to prevent her eroding you j and if that cannot be done, you mull ride round on frelh ground. If the fow is attended with her litter of pigs, it is lucky, and denotes a fuccefsful journey. It is unlucky to fee frit one magpye, and then more ; but to fee two denotes marriage or merriment ; three, a fuccefsful journey ; four, an unexpedled piece of good news j five, you will Ihortly be in a great company. To kill a magpye, will certainly be punilhed with fome terrible misfortune. If in a family, the youngell daughter Ihould be married before her elder fillers, they mull all dance at her wedding without fhoes : this will counteract their ill luck, and procure them hulbands. If you meet a funeral proctffion, or one paffes by you, always take off your hat : this keeps all evil fpirits attending the body in good humour. If, in eating, you mifs your mouth, and the victuals fall, it is very unlucky, and denotes approaching fiek- nefs. It is lucky to put on a Hocking the wrong fide out¬ wards : changing it alters the luck. When a perfon goes out to tranfaCl any important bufinefs, it is lucky to throw an old Ihoe after him. It is unlucky to prefent a knife, feifiars, razor, or any (harp or cutting inllrument, to one’s miltrefs or friend, as they are apt to cut love and friendlhip. To avoid the ill effeCts of this, a pin, a farthing, or fome trifling reeompenfe, mull be taken. To find a knife or razor, denotes ill luck and difappointment to the party. In the Highlands of Scotland, it is thought unlucky if a perfon fetting out upon a journey Humble over the threlhofd, or be obliged to return for any thing forgot¬ ten. If a fj iortfman fee any perfon Hopping over his gun or filhing rod, he expeCls but little fuccefs in that day’s diverfion. Sneezing is alfo deemed ominous. If one fneeze when making a bed, a little of the flraw or heath is taken out and thrown into the fire, that no¬ thing may diflurb the refl of the perfon who is to fleep in the bed. Among the fame people, fuccefs in any enterprife is believed to depend greatly upon the firH creature that prefents itfelf after the enterprife is under¬ taken. Thus, upon going to fhoot, it is reckoned lucky to meet a horfe, but very unfortunate to fee a hare, if flic efcape ; and upon meeting any creature deemed un¬ lucky, the befl means of averting the omen is to roll a Hone towards it. The Greeks attributed the fame ef¬ ficacy to the rolling of a Hone, though they greatly pre¬ ferred hilling the ominous animal, that the evil portend- * See Pot- ed might fall on its own head *. ter's Anti- The motions and appearances of the clouds were ^'^,6vo1-notlong ago confidered as certain figns by which the ' 04 )- Ikilful Highlander might attain to the knowledge of futurity. On the evening before new year's day, if a black cloud appeared in any part of the horizon, it was thought to prognoflleate a plague, a famine, or the death of fome great man in that part of the country over which it flrould appear to fet ; and in order to afeertain the place threatened by the omen, the mo- i ] O M E tions of this cloud were often watched through the whole night, if it happened to continue fo long vifible above the horizon. By the believers in this fuperflition there are days* as well as words and events, which are deemed ominous of good or bad fortune. The firH day of every quar¬ ter, midfummer, and new year’s day, are reckoned the mofl fortunate days in the year for aceomplifliing any dehgn. In the ifle, of Mull, ploughing, lowing, and reaping, are always begun on Tuefday, though the moH favourable weather for thefe purpofes be in this way frequently lofl. That day of the week on which the third of May falls, is deemed unlucky throughout the whole year. In Morven, none will upon any account dig peat or turf for fuel on Friday ; and it is reckon¬ ed unlucky to number the people, or cattle belonging to any family, and doubly fo it the number be taken on Friday. The age of the moon is alio much at¬ tended to by the vulgar Hiuhlanders. It is aliened, that during the mcreafe things have a tendency to grow and Hick together : and hence, in the ifle of Sky, fences, which are there made of turf, are built only at that time ; whilfl turf or peat for fuel are never, even in the mofl favourable weather, either made or flacked up but while the moon is in its wane. An opinion prevails in fome places, that if a houfe take fire during the increafe of the moon, the family to which it be¬ longs will profper in the world : but that if the fire happen while the moon is in the decreafe, the family will from that time decline in its circumflances, and fink into poverty. In attributing fuch influence to the moon, the fuper- ftitious Highlanders have the honour to agree with the philofophic Virgil, who in his Georgies gives the follow¬ ing fage inflrudlions to the hufbandman t Ipfa dies alios alio dedit ordine Luna- Felices, operum. in turn fuge : Septima pojl decimam fe/ix et ponere vitem, Et prenfos domitare boves, et licia telce xdddere ; nona fugee mehor, contraria furtis. The lucky days in each revolving moon For labour choofe : the fifth be lure to Ihun. * * -* / * The feventh is, next the tenth, the befl to join Young oxen to the yoke, and plant the vine. Then weavers flreteh your flays upon the weft : The ninth is good for travel, bad for theft. Dryden^ From this coincidencp of the fuperftition of the Roman poet with that of the natives of Mull and Mor¬ ven, we are ftrongly inclined to adopt the hypothe- fis of the gentlemen who favoured us with this accu¬ rate account of Highland omens. He juftly obferves, that this fuperftitious pra&iee of auguring good or ill from trifling events, and from the particular phafes of the moon, has no connexion whatever with popifh prieftcraft : he ftiows that the Romifh clergy, even in the darkeft age, were at pains to eradicate it as idle and impious 5 and he therefore infers, that it muft be a relick of Hruidilm handed down by tradition from, an era prior to the introduction of Chriflianity into the Highlands and ifles of Scotland. That the Druids- were Omen. Omen II Omoa. O M O [ 142 ] O M O were acquainted with the particular do£lrines of Pytha¬ goras has been thown elfewhere (fee Druids) j that j Virgil was no ftranger to tlie Pythagorean philofophy is known to every fcholar j that Pythagoras and his fol¬ lowers were addicted to the dotages of Magic has been made apparent in that article ; and therefore it appears to us probable at lead, that the attention paid to pretended omens, not only in the Highlands, but alfo in the low country of Scotland, and indeed among the vulgar in every country of Europe, is a remnant of one of the many fuperftitions which the Druids impofed upon their deluded followers. That it is contrary to every principle of found philofophy, all philofophers wall readily acknowledge ; and whoever has ftudied the wri¬ tings of St Paul mud be convinced that it is inconddent with the fpirit of genuine Chridiamty. OMENTUM, or Epiploon, the Caw/, in Anatomy, a membranaceous part, ulually furnidied with a large quantity of fat ; being placed under the peritonaeum, and immediately above the intedines. See Anatomy, N° 90. OMER, in Jewidi antiquity. See CoRUS. St OMER’s, a drong, fortified, large, and populous town of France, in the department of the draits of Calais, with a cadle and a bifliop’s fee. It is a fortrefs of condderable importance, and furrounded on one dde with a large morafs •, and about it there are many duices, which ferve to carry the water off when it is overflow¬ ed 5 and in the midfl of the morafs there is a fort of floating iflands covered with verdure and trees. The cathedral is a handfome drudture •, and there are other fine buildings, with a rich Benedifline abbey. The French became maders of this place in 1679. It is feated on the river Aa, and on the fide of a hill, eight miles north-ived of Aire, and 135 north of Paris. E. Long. 2. 20. N. Lat. 54. 45. OMOA, a Spanifh town and fortification on the fouth fide of the bay of Honduras, N. Lat. 15. 50. W. Long. 89. 50. from London. It is the key to the bay ; and fuch is the depth of the ivater, that fhips of any burden may ride in the harbour Avith fafety. It is a place of the utmod importance to Spain, as the regider {hips to and from Guatimala are fent to it in the time of Avar. The toAvn was fird edabliflied in 1751, under the command of Don Jofeph Antonio de Palmo. At that period the inhabitants Avere about 20 white men, 60 mulattoes and free negroes, and 200 flaves to the king of Spain •, and the military force con¬ fided of about 30 foldiers, befides officers. The fort was originally compofed of fand confined in boarded coffers, and faced Avith half-burnt bricks. It Avas de¬ fended by 12 fine brafs 24 pounders mounted, four or five iron guns of different bores, and fome field-pieces. The Spaniards, fenfible of the importance of the place, afterAvards fortified it at an incredible expence, the done of which the Avails are built having been raifed from the fea, and brought from the didance of 20 leagues. The outworks Avere not completely finiflied in the year 1779, though 1000 men had then been employed upon them for 20 years. Towards the end of that year an expedition was un¬ dertaken againd this fortrefs, in confequence of one formed by the Spaniards againd the Britiffi logAVood ^cutters in the bay of Honduras and on the Mofquito 5 fliore. The latter, finding themfelves hard preffed by their enemies, applied to General Dulling governor of Jamaica for aflidance 5 Avho accordingly fent a detach¬ ment to their relief under Captain Dalrymple, Avith neceffary fupplies of arms, ammunition, and artillery. Before their arrival, hoAvever, the Spaniards had taken poffeflion of St George’s Key, the chief fettlement of the Britiffi in thefe parts, Avhich they plundered, and took a number of prifoners ; but thofe Avho efcaped, being joined by a body of their countrymen, retook it, and forced the enemy to retire. In the mean time Captain Dalrymple, who had been informed of the lofs of the place, was hadening to the relief of the inhabitants, and in his Avay fell in with Admiral Par¬ ker, Avho Avas in qued of fome regifler fliips \ but which, retreating into the harbour of Omoa, were too drongly protefted by the fort there to be attacked by fea. As the Spaniards, hoAvever, had hoav been compelled to abandon St George’s Key, it Avas propofed to unite the Britifh forces by fea and land, and to attempt the con- qued of this fortrefs. As the force under Captain Dal¬ rymple Avas too inconfiderable to attempt the fort by land, it was augmented by the marines of the fquadron and a flrong party of the fettlers; though, after all, it did not exceed the number of the garriion who oppofed them. The troops Avere landed at about nine miles diftance from the fort in the dufk of the evening, Avith a defign to march diredlly fonvard, in order to furprife and carry it by efcalade in the night time. No roads, hoAvever, being found, they Avere obliged to explore their w ay through narroAv foot-paths, moraffes, and over mountains fo befet Avith precipices, that they Avere obliged, in or¬ der to avoid them, to make ufe of lights made of the cabbage tree. In confequence of thefe impediments they were yet at a confiderable didance from the fort, when the approach of day difeovered them to the ene¬ my. An engagement enfued, in Avhich the Spaniards were quickly routed and driven into the toAvn : from whence as they continued to fire upon the Britilh, it was found neceffary to fet fire to it, though very much againd the inclination of the affailants. In the mean time the fquadron took the opportu¬ nity, while the toAvn Avas in flames, to come into the bay, and approach the fort with an intention to batter it j but the garrifon returned the fire fo brifkly, that no impreffion could be made by that of the fquadron, which Avas detained by Avant of Avind from approach¬ ing fufficiently near. The troops then, being maders of the ground adjacent to the fort, eredted feveral batteries in fuch fituations as were mod proper for an¬ noying it •, but though they carried on their operations with great vigour, it Avas dill found that heavier artil¬ lery than any they poffeffed Avould be requifite, the Avails being no lefs than 18 feet in thicknefs; in confequence of which they refolved dill to attempt the place by el- calade. The attempt was made on the 2id of Odlober, early in the morning. The troops entered the ditch, which fortunately for them happened to be dry, and fixed their fealing ladders againd the Avails, which Avere near 30 feet high. Tavo feamen mounted fird ; and, with admi¬ rable courage and prefence of mind, dobd by the ladder which they had mounted, to guard it till others afeend- Omoa. / O M O [i Omoa. ed ; and boldly prefented their pieces againft a large " M party drawn up to receive them, though they prudently retained their fire till their comrades came up. 1 he fquadron, now drawing near, kept up a heavy and continual fire upon the fort, while the Spaniards were ftruck with fucli furprife at the exceflive celerity and boldnefs of the afiailants, that they remained mo- tionlefs and unable to oppofe their enemies, notwith- ftanding the exhortation and example of their officers. From this panic they never recovered ; and while the feamen and foldiers continued to fcale the walls with amazing quicknefs, the Spaniards never made any ef¬ fort to defend themfelves. About 100 of them efcap- ed over the walls on the oppofite fide of the fort 5 the remainder furrendered at diferetion. The whole of this tranfaffion reflecled the highefl luftre both on the conduft and courage of the Britifh ; and an inffance of heroifm is related in a Eritifh failor to which hiftory affords nothing fuperior. This man, having fealed the walls, had armed himfelf with a cut- lafs in each hand. Thus armed, he met with a Spa- nifh officer unarmed, and juft roufed from deep. The generous tar fcorned to tkke advantage of his condition, and therefore prefented him with one of his own cut- laffes faying, “ You are now on a footing with me !” The officer, however, was too much ftruck with ad¬ miration at his conduit to accept the offer, and took care to make the circumftance fufficiently known. The value of the booty taken on this occafion amounted to three millions of dollars ; but the lofs molt fenfibly felt by the Spaniards was that of 250 quintals of quick- filver, a commodity indifpenfably neceflary in ex trail¬ ing the precious metals from their ores. They offered therefore to ranfom it at any price : but though the retention of it was far from affording a profit equal to t iiat offered by the Spaniards, the Britifh commanders abfolutely refufed to part with it, on account of the ad¬ vantages the enemy would derive from having the metal in their poffeffion. For the fame reafon they refufed to accept of any ranfom for the fort, though the governor offered to lay down 300,000 dollars for it. The Spa- niih military and the inhabitants were treated with the utmoft humanity ; their perfonal effects remaining un¬ touched : and this generofity muft have appeared to greater advantage, when contrafted with die beha¬ viour^ of their own countrymen at Honduras, where the Britifh were treated with remarkable feverity. The church plate and ornaments were reftored, on condi¬ tion that the terms of capitulation fhould be faithfully In a fliort time, however, it appeared that it would have been better to have accepted of a ranfom for the fort, as. from circumftanees at that time it could not be retained in the poffeftion of Britain. A garrifon ■was indeed left for its defence on the departure of the Biitilh fquadron ; but as it was very inconfiderable, on account of the fmall number of men that could be fpa- ied, the Spaniards quickly determined to make' an at¬ tempt to regain the fort. For this purpofe a bodv of 2000 men were coMed, who invefted it on the 2 cth of November. 1 lie Britifh defended it with the ut¬ moft bravery keeping up a conftant fire on the ene¬ my, and obliging them to retire for fhelter, and take up their quarters behind a hill. Here they made pre¬ parations for an affault, in which their numbers left 43 ] O M P the fuccefs, as they fuppofed, by no means dubious. T he garrifon was therefore fummoned to furrender, with a promife of the honours of war and a fafe con¬ veyance to Great Britain, denouncing at the fame time the utmoft vengeance in cafe of a refufal 5 which being refufed, the neceffary preparations were made for an ef- calade. 1 he condition of the garrifofi was now fuch as could afford very little hope of being able to make any ef- fedfual refiftance. 1 hey were but 85 in number, moft of whom were become incapable of duty either from illnefs or exceflive fatigue. I hey were now alfo ob¬ liged to make one centinel anfwer for five, by ftiifting his place, and challenging as many times. There was no furgeon to attend the fick and wounded 5 nor had they even any water but what came from a floop of war that lay abreaft of the fort. In this defperate fituation, they. refolved, notwithftanding the menaces of the Spanifh commander to render the place, as unferviceable as they could. For this purpofe they fpiked up all the guns ; deftroying the ftores and ammunition that could, not be carried.off: they even locked the gates of the fort, after which they embarked without the lofs of a fingle man. All this was performed in defiance of the large force that befieged them ; and the exploit, when duly confidered, muft appear not lefs a matter of aftoniftiment than the extraordinary manner in which, the.fort had been taken. The officer who command¬ ed in this remarkable retreat was Captain Hulke of the navy. OMOPHAGIA, an ancient Greek feftival, in ho¬ nour of Bacchus, furnamed Omophagos, i. e. eater of raw fleffi. 1 his feftival was obferved in the fame man¬ ner with the other feftivals of Bacchus, in which they counterfeited madnefs. What was peculiar to it, was, that the worffiippers ufed to eat the entrails of ’goats' raw and bloody, in imitation of the god, who was fun- pofed to do the fame thing. ^ OMPHACJNE oil-, a vifeous brown juice extraft- ed from green olives. With this oil the ancient at/i- let*, when going to wreftle, anointed themfelves ; and when that gymnaftic exercife was over, they rolled themfelves in the fand, which, mixing-with the oil and fweat on their bodies, conftituted the Jlngmenta fo high¬ ly efteemed in the cure of feveral difeafes. This precious medicine was. carefully feraped off the body of the ath- leta with a kind of inftrument fomething like a comb which was calledy^z'/fr; and fuch was the demand for the ferapings, that they were a very.lucrative article of trade. OMPHALE, in fabulous hiftorv, a queen of Ey« dia, daughter of Jardanus. She married Tmolus, who at his death left her mifirefs of his kingdom. Qmphale had been informed of the great exploits- of .Hercules, and wiftied to fee fo illuftrious a hero. He? wifti was foon gratified. After the murder of Eurytus, Hercules fell fick, and was ordered to be fold as a flave, that he might recover his health and the right ufe of his fen- fes. Mercury was commiffioned to fell him, and Om- phale bought him, and reftored him to liberty. The hero became enamoured of his miftrefs, and the queen favoured his paffion, and had a fon by him, whom fome call Agelaus, and others Lamon. From tiffs fon were defeended Gyges and Croefus ; but this opinion isf dif¬ ferent from the account which makes tbefe Lydian monarch? Omoa Omphale. ON [ Oiriphale rrumarelis fprlng from AIcceus, a fon of Hercule II one of the female fervants of Ompliale. On. _ . . . ^ . Hercules is reprefented by the poets as fo defperately enamoured of the queen, that, to conciliate her efieem, he fpins by her fide among her women, while the covers herfelf with the lion’s ikin, and arms herfelf with the club of the hero, and often tlrik.es him with her fandals, for the uncouth manner with which he holds the diftaff, &c. Their fondnefs was mutual. As they once tra¬ velled together, they came to a grotto on Mount J mo- lus, where the queen drelfcd herfelf in the habit of her lover, and obliged him to appear, in a female garment. After they had tupped, they both retired to reft in different rooms, as a facrifice on the morrow to Bac¬ chus required. In the night Faunus, or rather Pan, who was enamoured of Omphale, introduced himfelf into the cave. Pie went to the bed of the queen, but the lion’s tkin perfiiaded him that it was the drefs of Hercules •, and therefore he repaired to the bed of Her¬ cules, in hopes to find there the objefl of his affec¬ tions. The female drefs of Hercules deceived him, and he laid himfelf down by his fide. The hero was awa¬ kened, and kicked the intruder into the middle of the cave. The noife awoke Omphale, and Faunus wasdif- covered lying on the gound, greatly difappointed and alhamed. OMPHALE A, a genus of plants belonging to the monoecia clafs •, and in the natural method ranking with thofe of which the order is doubtful. See Botany In¬ dex. OMPHALO-mesentertc, in Anatomy. All fee- tufes are wrapped up in at leaft two coats or mem¬ branes-, moft of them have a third, called allantoides, or urinary. Some,'as the dog, cat, hare, &c. have a fourth, which has two blood-veffels, viz. a vein and an ar¬ tery, called omphalo-mefenterics, becaufe palling along the ft ring to the navel, and terminating in the mefen- terv. OMRAH, a man of the firft rank in the Mogul empire ; a nobleman. It is the plural of the Arabic ameer. ON, in Ancient Geography, a city of Egypt facred to the fun, and by the Greeks, on that account, called He¬ liopolis. (See Heliopolis). It was remarkable for the wifdom and learning of its priefthood, and for the fpacious building in which they cultivated the ftudies of philofophy and aftronomy. The priefts of On were eftcemed more noble than all the other priefts of Egypt. They were always privy counfellors and minifters of ftate ; and therefore, when Pharaoh refolved to make Jofeph prime minifter, he very wifely gave him in mar¬ riage a daughter of the prieft of On, thereby incorpo¬ rating him into the moft venerable call in Egypt. Bi- ftiop Warburton thinks that the fuperior nobility of the priefts of On was chiefly owing to their high antiquity and great learning. That they were much given to the ftudy of aftronomy, we know from the teftimony of 144 ] O N A by very different opinion), it is certain they taught that the Sun is in the centre of its fyftem, and that all the other bodies move round it in perpetual revolutions. This noble theory (he continues) came with the reft of the Egyptian learning into Greece (being brought thither by Pythagoras, who received it from Oenuphis *, a prieft of On) j and after having given the moft diftin- guithed luftre to his fchool, it funk into obfeurity, and fuffered a total eclipfe throughout a long fucceflion of learned and unlearned ages ) till thefe times reftored its ancient fplendour, and immoveably fixed it on the uner¬ ring principles of fcience.” If it be true, as fome philofophers allege, that Mofes appears from the firft chapter of Genefis to have been acquainted with the true lolar fyftem, this ac¬ count of the origin of that fyftem is extremely proba¬ ble. As it is of no importance to the civil or religious conftitution of a ftate whether the fyftem of Ptolemy or that of Copernicus be admitted by the people, we can¬ not reafonably fuppofe that the Jewifti lawgiver was taught aftronomy by a revelation from Heaven. But there can be no doubt of his knowing as much of that fcience as the priefts of On ,■ for we know that he was inftrutfed in all the wifdom of the Egyptians ■, and therefore, if he held the fun to be in the centre of the fyflem, it is morally certain that the fame thing was held by that priefthood. ONANIA, or Onanism, terms employed to denote the crime of felf-pollution, mentioned in Scripture to have been committed by Onan, and punilhed in him with death. This practice, however common, hath among all na¬ tions been reckoned a very great crime. In Scripture, befides the inftance of Onan above mentioned, we find felf-pollulers termed effeminate, unclean, ji/thy, and abo¬ minable. Even the heathens, who had not the advan¬ tage of revelation, were of the fame opinion, as appears from the following lines of Martial. * Tint, de If. et Ofir, p. 632. Steph. ed. Hoc nihil ejffe putes ! feel a'; ef, tnihi crede; fed ingens Quantum vix animo concipis ipfe tuo. You think ’tis nothing ! ’tis a crime, believe ! A crime fo great you fcarcely can conceive. Dr Tiffot has publithed a treatife on the pernicious effects of this Ihameful practice, which appears to be no lefs baneful to the mind than to the body. He^ be¬ gins with obferving, that, by the continual wafte of the human body, aliments are required for our fupport. Thefe aliments, however, require certain preparations in the body itfelf; and when by any means we become fo altered that thefe preparations cannot be effected, the beft aliments then prove infufficient for the fupport of the body. Of all the caufes by which this morbid alteration is brought on, none is more common than too copious evacuations *, and of all evacuations, that of the femen is the moft pernicious when carried to ex- cefs. It is alfo to be obferved, that though excefs in So0 ve^ is produftiye of very dangerous djfor- oirauo, auu , ' /-.I . r-.n vnt an ennal evacuation bv felf-pollution, which they fhould be attached to the ftudy of that fyftem over which their god, the Sun, prefided, not onlv in his mo¬ ral, but alfo in his natural capacity. The learned prelate affirms, that “ whether they received the do&rine from original tradition, or invented it at hazard (which laft fuppofition he thinks more probable, though we are of a ders, yet an equal evacuation by felf pollution, which is an unnatural way, is produftive of others ftill more to be dreaded. The confequcnces enumerated by Dr Tiffot are as follow’: 1. All the intelle&ual faculties are weakened j the memory fails j the ideas are confufed, and the patient fome times Oniinia Oneehoura. ONE [i fometiities even falls into a fliglit degree of infanity. They are continually under a kind of inward reftleflhefs, and feel a conftant anguifh. They are fubjeft to giddi- nefs } all the fenfes, efpecially thofe of feeing and hear¬ ing, grow weaker and \Veakef, and they are fubject to frightful dreams. 2. J he ftrefigth entirely fails, and the growth in young perfons is confiderably checked. Some are af- fli^led with almoft continual watching, and others dofe almolt perpetually. Almoft all of them become hy¬ pochondriac or hyfteric, and are afflided with all the evils which attend thefe diforders. Some have been known to fpit calcareous matters 5 and others are afflided with coughs, flow fevers, and confump- tions. 3. The patients are -affeded with the moft acute pains in different parts of the body, as the head, breaft, fto- mach, and inteftines ; while fome complain of an ob~ tufe fenfation of pain all over the body on the flighteft impreflion. 4. There are not only to be feen pimples on the face, which are one of the mod common fymptoms ; but even blotches, or fuppurative puftules, appear on the face, nofe, breaft, and thighs 5 and fometimes fleftiy ex- crefcenees arife on the forehead. 5. The organs of generation are alfo affeded 5 and the femen is evacuated on the flighteft irritation, even that of going to ftool. Numbers are afflided with an habitual gonorrhoea, which entirely deftroys the vigour of the conftitution, and the matter of it refembles a fetid fanies. Others are affeded with painful pria- pifms, dyfuries, ftranguries, and heat of urine, with painful tumours in the tefticles, penis, bladder, and fpermatic cord ; and impotence in a greater or lefs de¬ gree is the never-failing confequence of this deteftable vice. 6. The fundions of the inteftines are fometimes total¬ ly deftroyed 5 and fome patients complain of coftivenefs, others of diarrhoea, piles, and the running of a fetid matter from the fundament. With regard to the cure, the firft ftep is to leave off thofe pradices which have occafioned the difeafe ; which our author afferts is no eafy matter 5 as, accord¬ ing to him, the foul itfelf becomes polluted, and can dwell on no other idea ; or if (he does, the irritability of the parts of generation themfelves quickly recal ideas of tlfe fame kind. This irritability is no doubt much more to be dreaded than any pollution the foul can have received ; and by removing it, there will be no oc- cafion for exhortations to difcontinue the pradice. The principal means for diminiflung this irritability are, in the firft place, to avoid all ftimulating, acrid, and fpi- ced meats. A low diet, however, is improper, becaufe it would further reduce the body, already too much emaciated. The food ftiould therefore be nutritive, but plain, and fhould confift of flelh rather roafted than boil¬ ed, rich broths, &c. ONC A and Once. See Felis, Mammalia Index. ONEEHOURA and ONEEHOW, two fmall iflands of that clufter which was difeovered by Captain Cook, and by him called the Sandwich IJlands. (See Sandwich Islands). Oneehoura is very fmall, and its chief produce is yams. Oneehow is confiderably larger, being about ten miles over. It is remarkable for the great quantity of excellent yams which it produces, Vol, XV. Part I. 45 1 O N E and for a Iweet root called tee or tea, which is generally Oneehoura about the thicknefs of a man’s wrift, though fometimes j! much larger. This root, which the natives commonly ^n^”cn" bake previous to their bringing it to market, is of a wet > - y - clammy nature, and with proper management makes ex¬ cellent beer. ONEGA, a river and lake of the Ruffian empire, between Mufcovite Carelia, the territory of Cargapol, and Swedifh Carelia. It is ioo miles in length and 40 in breadth, having a communication with the lake Ladoga, and confequently with Peterftmrgh. The river, which has its fource in Cargapol, and gives its name to a country full of woods, falls into the White fea. ONEGLIA, a fea port town of Italy, in the terri¬ tory of Genoa, with the title of a principality j but it belongs to the king of Sardinia, as well as the province, which abounds in olive trees, fruit, and wine. It has often been taken and retaken in the wars of Italy, which is no wonder, as it is an open place. The French and Spaniards had poffeffion of it in 1744, but were driven out by the Piedmontefe ; however, they retook it the following winter. It was laft taken by the French in 1794. E. Long. 7. 51. N. Lat. 43. 58. ONEIROCRITIC A, the art of interpreting dreams j or a method of foretelling future events by means of dreams. See Dream, Divination, &c.—The word is formed from the Greek “ dream,” and XglTlXY), of y-gicyius, judgment.” Some c^ll it andro¬ cratic a; and derive it from ovu^os and “ I poffefs, I command.” It appears from feveral paffages of Scripture, that there was, under the Jewifti difpenfation, fuch a thing as foretelling future events by dreams ; but then there was a particular gift or revelation required for that purpofe. Hence it has been inferred, that dreams are really fig- nificative, and do forbode fomething tt> come ; and all that is wanting among us is the oneirocritica, or the art of knowing what ; yet it is the opinion of many, that dreams are mere chimeras ; bearing indeed fome rela¬ tion to what has paffed, but none to what is to come. As to the cafe of Jofeph, it was poflible for God, who knew all things, to difeover to him what was in the womb of fate •, and to introduce that, he might take the occafion of a dream. ONEIROCRITICS, a title given to interpreters of dreams, or thofe who judge of events from the circum- fiances of dreams. There is no great regard to be had to thofe Greek books called oneirocritics ; nor do we know why the patriarch of Conftantinople, and others, ftiould amufe themfelves with writing on fo pitiful a fubjeH. Rigault has given us a collection of the Greek and Latin works of this kind •, one attributed to Aftramp- fichus 5 another to Nicepliorus, patriarch of Conftanti¬ nople ; to which are added the treatifes of Artemidorus and Achmet. But the books themfelves are little elfe than reveries; a kind of waking dreams, to explain and account for fleeping ones. The fecret of oneirocriticifm, according to them all, confifts in the relation fuppofed to be between the dream and the thing fignified : but they are far from keeping to the relations of agreement and fimilitude j and frequently have recourfe to others of diflimilitude and contrariety. Concerning oneirocritics and onei- T rocritica, O N K [ 146 ] O N T Oneirocri- rocrllica, the unlearned reader will find much informa- tl“ tion in Warburton’s Divine Legation of Mofes, and the Onkelos b0°ks to which he refers. > ' ■ ONESI^i, THERMJE, were, according to Strabo, excellent baths, and falutary waters, at the foot of the Pyrenees in Aquitania. Near the river Aturus Hands at this day the town Bagneres, famous for its waters, which appear to be the Onefice of Strabo : fituated in the county of Bigorre in Gafcony, near the river Adour. ONI At, oppidum and Templum, fJofephus) 5 fo called from Onias, the high-prieft of the Jews in Egypt} who built a temple in imitation of that at Je- rufalem, by permiffxon ot the king of Egypt, on the fpot where Hood the temple of Diana Agreftis in Le- ontopolis : it was encompaffed with a brick wall, and had a large tower like that at Jerufalem (Jofephus) ; it was the metropolis of the Nomos Heliopolites, (Pto¬ lemy) •, becaufe in Strabo’s time Heliopolis Avas fallen to decay. ONGLEE, in Heraldry, an appellation given to the talons or claws of beafts or birds when borne of a dif¬ ferent colour from that of the body of the animal. ONION. See Allium, Botany Index; and for the mode of its cultivation, fee Gardening Index. ONISCUS, a genus of infefts belonging to the or¬ der of aptera. See Entomology Index. ONKELOS, furnamed the Profelyte, a famous rabbi of the firfl. century, and the author of the Chaldee Targum on the Pentateuch. He flourithed in the time of Jefus Chrift, according to the Jewith writers ; Avho all agree that he Avas, at leaft in fome part of his life, contemporary with Jonathan Ben Uzziel, author of the fecond Targum upon the prophets. Dean Prideaux thinks he Avas the elder of the two, for feveral reafons : the chief of Avhich is the purity of the ftyle in his Tar¬ gum, therein coming neareft to that part of Daniel and Ezra Avhich is in the Chaldee, and is the trueft ilandard of that language, and confequently is the moil ancient •, fince that language, as Avell as others, Avas in a conftant flux, and continued deviating in every age from the original : nor does there feem to be any rea- fon Avhy Jonathan Ben Uzziel, Avhen he undertook his Targum, ftiould pafs over the law, and begin Avith the prophets, but that he found Onkelos had done this Avork before him, and Avith a fuccefs Avhich he could not exceed. Azarias, the author of a book entitled Meor Enaun, or the light of the eyes, tells us, that Onkelos Avas a profelyte in the time of Hillel and Samnai, and lived to fee Jonathan Ben Uzziel one of the prime fcholars of Hillel. Thefe three doftors flourilhed 12 years be¬ fore Chrift, according to the chronology of Gauz ; Avho adds, that Onkelos Avas contemporary Avith Ga¬ maliel the elder, St Paul’s mafter, Avho Avas the grand- fon of Hillel, Avho lived 28 years after Chrift, and did not die till 18 years before the deftruftion of Jerufalem. However, the fame Gauz, by his calculation, places Onkelos 100 years after Chrift ; and to adjuft his opi¬ nion Avith that of Azarias, extends the life of Onkelos to a great length. The Talmudifts tell us that he af- fifted at the funeral of Gamaliel, and Avas at a prodi¬ gious expence to make it moft magnificent. Dean Prideaux obferves, that the Targum of Onkelos is rather a verfion than a paraphrafe ; fince it renders the Ontario. Hebrew text word for Avord, and for the moft part ac- Onkelos curately and exaftly, and is by much the bell of all this fort: and therefore it has always been held in __ efteem among the Jcavs much above all the other Tar- gums: and being fet to the fame mufical notes Avith the HebreAV text, is thereby made capable of being read in the fame tone with it in their public affemblies.— From the excellency and accuracy of Onkelos’s Tar¬ gum, the dean alfo concludes him to. have been a native Jew, fince Avithout being bred up from his birth in the Jewilh religion and learning, and long exercifed in all the rites and doctrines thereof, and being alfo thorough ¬ ly Ikilled in both the HebreAV and Chaldee languages, as far as a native Jcav could be, he can fcarce be thought thoroughly adequate to that Avork Avhieh he performed) and that the reprefentinghim as a profelyte feems to have proceeded from the error of taking him to have been the fame Avith Akilas, or Aquila, of Pontus, author of the. Greek Targum or verfion of the prophets and Hagio- graphia, Avho Avas indeed a Jewifli profelyte. ONOCLEA, a genus of plants belonging to the cryptogamia clals and order of Filices. See Botany' Index. ONOMANCIA, or rather Onomantia, a branch of divination, which foretels the good or bad fortune of a man, from the letters in his name. See the article Divination and Name. From much the fame principle the young Romans toafted their miftreffes as often as there Avere letters in their names : Hence Martial fays, Ncevia fex cyathis,feptem Juf ina bibatur. ONOMATOPOEIA, in grammar and rhetoric, a figure Avhere words are formed to refemble the found made by the things fignified •, as the buzz of bees, the cackling of hens, &c. Refemblances of this kind are often fancied Avhen they are not real, though, no doubt,, there are in every language fome Avords of which the found is very like to that which thofe Avords are em¬ ployed to exprefs. Yet, to the mortification of gram¬ marians and rhetoricians, conjunctions, Avhich have been juftly pronounced no parts of fpeech, are the only founds uttered by men that are wholly natural, and thefe are fevver than is commonly fuppofed. See' Gram¬ mar and Language. ONONIS, a genus of plants, belonging to the dia- delphia clafs. See Botany Index. ONOPORDUM, a genus of plants, belonging to the fyngenefia clafs) and in the natural method ranking under the 49th order, Compoftce. See Botany Index. ONOSANDER, a Greek author and Platonic phi- lofopher, Avho AVrote Commentaries on Plato’s Politics, which are loft : but his name is particularly famous for a treatife entitled Aeyoj 2rg!*T>iy t—,j OPERATION, in general, the aft of exerting or exereifing fome power or faculty, upon which an effeft follows. Operation, in Surgery and Medicine, denotes a me¬ thodical aftion of the hand on the human body, in order to re-eflablifh health. OPHID1UM, a genus of fifhes belonging to the or¬ der of apodes. See Ichthyology Index. OPHIOGLOSSUM, Adder’s Tongue, a genus of plants, belonging to the cryptogamia clafs, and to the order Fi/ices. See Botany Index. O P H I O L O G Y. INTRODUCTION. Hiftorical notices of .3 Ancient. 4 Modern. Definition.. rT',HE term ophialogy is compofed of two Greek words, * namely «£<;, a ferpetit, and heyo?, a difeourfe, and confequently denotes that branch of zoology- which ■ treats of ferpents. The latter conftitute an order in the clafs of amphibious animals. They are covered with feales, breathe by means of lungs, and are deflitute of „ feet and fins. The hideous afpeft of fome of the fpecies, and the poifonous properties of others, long contributed to pre- ©phioiogical venp any deliberate inveftigation of their ilrufture, con- wnters. ftitution, and modes of exitlence. Hence the ancients, who at belt had very imperfeft notions of claffification, fometimes indicate different fpecies under the fame name, or beftow different appellations on the fame fpe¬ cies, and moreover blend their vague deferiptions with the embellifhments or abfurdities of fable. Among the moderns, few naturahlls have direfted their refearches to the hiftory of ferpents. “It mull be acknowledged,” obferves Dr Ruffel, “ that it offers no attraftive allurements •, and that thofe who, from other avocations, can only fpare tranfient attention to fubjefts of natural hillory, are more likely to prefer objefts lefs difgufting, and experiments accompanied with lefs cruelty and perfonal danger. Even the eager and re- folute naturalift has to contend with many difficulties in this path of refearch. He cannot at once divert himfelf of the abhorrence, next to innate, of thefe rep¬ tiles •, nor can he foon acquire a dexterity in handling them, with that calmnefs requifite tor his own fafety. The fearch for plants, for birds, or even infefts, is com¬ paratively partime, or pleafurable occupation 5 but in the aftual puriuit of the difgufting race of ferpents, he ftands in need of affiftants, who are not at all times to be procured *, and if he rely folely on the diligence of fuch as he may employ, he will find himfelf expofed to the chagrin of ineeffant difappointment.” Seba has indeed prefented us with a numerous cata¬ logue ^ but his fpecies are too multiplied, and his de¬ feriptions too concife. Catelby was more felicitous to defign and colour his ferpents, than to unfold their dif- 5 Seba. 6 Cateiby. Gronovius. criminating charafters. The defcriptions of Gronovius 2 ate for the moft part wrell and acurately detailed j but they are unprovided with the fpecific names. § Linnaeus, availing himfelf of the works to which wre LinnseuSo have juft alluded, of the difeoveries of Garden, and of his own difeernment, publifhed his method of diftin- guiffiing the .fpecies by the number of fcaly plates on the abdomen, and beneath the tail. Experience has indeed proved, that thefe do not always conftitute an infallible criterion, and that more obvious marks, fuch as the relative fize of the head, the length of the body and tail, &c. mull fometimes be reforted to : it muft, however, be allowed, that the celebrated Swediffi naturalift paved the way to a far more accurate nomenclature of ferpents than had yet appeared, and that the value of his feien- tific diftinftions is greatly enhanced by the interefting notices on the fame fubjeft, which are inferted in his Amcenitates Acadcmicce, and in the firft and fecond vo¬ lumes of his Adolphian Mufeum. 9 The count de la Cepede.has in fome refpefts improved La Cepedc. the Linnaean arrangement, and exhibited a more corn"sl)a^° plete catalogue than any of his predeceffors. Dr Shaw has likewife difplayed his ufual fagacity in the fecond part of the third volume of his General Zoology, which is allotted to his expofition of the ferpent tribes. To 11 thefe we may add, Owen on the natural hiftory of Owen, ferpents, Klein’sTentamen Herpetologiae, Blumenbach’s Kiein’ c“ Beytragzur Naturgefchichte der Schlangen, Schneider’s Allgemeine Betrochtungen uber die Eintheilung und Kennzeiehen der Schlangen, Merian’s Beytrage zur « gefchichte der Amphibien, Lanrenti’s Specimen Medi- cum, continens Synopfin Reptilium, Bonaterre’s Ophi- ologie, in the Encyclopedic Methodique, Latreille’s Hiftoire Naturelle des Reptiles, Ruffel’s Account of In¬ dian Serpents, See. &c. Anatomy and Phyftology of Serpents. The body of ferpents is very long when compared Bedy. with its thkknefs ; and is femetirnes quite cylindrical, or rounded, fometimes compreffed on the fides, fome¬ times flat on the under furface, and fometimes attenuated towards the tail. It is ufually covered with feales •, but fometimes naked, either rough, or flippery to the touch, O P H I O L O G Y. ‘ Anatomy of Serpent' 13 Head. Mouth. *5 Snout. 16 Jaws. I? Lips. 18 Teeth. Fangs. Tongue. 21 ■Ej/ts. 22 Noltrils. and banded, fpotted, or reticulated ; the Ikin exhibiting ■ great varieties in the tints and diiiribution of the co- ' lours. The head is either diftindd from the trunk, or con¬ founded with it, and is convex, or flattened, oval, trian¬ gular, or heart-fhaped, and furnilhed with plates, or im¬ bricated fcales. It includes the mouth, fnout, jaws, lips, teeth, tongue, eyes, and noftrils. There is no vilible external ear ; though animals of this order doubtlefs poflefs the faculty of hearing. The mouth is that cavity which is fituated between the jaws. It is very large in proportion to the lize of the head, and is capable of being widely extended. The fnout is the anterior part of the head: it is flanting, elongated, obtufe, truncated, of"reflexed. The jaws, which are either of equal or unequal length, are com- pofed of two bones, which do not, as ours, open in the manner of a pair of hinges, but are held together at the roots, by a ftretching mufcular Ikin, fo as to open as widely as the animal choofes to ftretch them. By this contrivance ferpents are enabled to fwallow animals thicker than themfelves. The lips ax-e entire, notched, or reflexed. The teeth, in the jaws, are generally fliarp-pointed, and, in ferpents not poifonous, are difpofed in three rows in the upper jaw, one row exterior and two interior. The under jaw is fometimes provided with a Angle row. The noxious fpecies are furniflied with ca¬ nine teeth, or fangs, of a tubular Itrufture, Atuated in the projecting part of the upper jaw, commonly of a much larger Aze than the other teeth, and frequently accompanied by, fmaller or fubfidiary fangs, apparently deltined to fupply the principal ones, when loll either by age or accident. The fangs are Atuated in a peculiar bone, fo articulated with the reft of the jaw, as to ele¬ vate or deprefs them at the pleafure of the animal. In a quiefeent ftate they are recumbent, with their points direCted inwards or backwards; but, in the moment of irritation, their pofltion is altered by the mechanifm of the above-mentioned bone, in which they are rooted, and they become almoft perpendicular. The tongue is ufually ftraight and (lender, compofed of two long and rounded flelhyfubfiances, which terminate in {harp points, and are very pliable. They unite at about two thirds length, and the root is connected to the neck by two tendons, which give the whole organ a great variety and facility of motion. In molt fpccies, the tongue is al¬ moft wholly inclofed in a fneath, or integument, from which the animal can dart it out of its mouth, without opening its jaws ; the upper mandible having a fmall notch, through which it can pafs. Some of the viper kinds have tongues a fifth part of the length of their bodies, and, as they are conftantly darting them out, terrify thofe who are ignorant of the real Atuation of the poifon. The eyes are fmall, when compared with the length of the body, and greatly vary in refpeCt of livelinefs and colour. In fome fpecies the upper eyelid is wanting, while others have a nictitating membrane, or fkin, which keeps the organ clean, and preferves the fight. In all, the fubftance of th? eye is hard and horny, the crvftalline humour occupying a.great part of the globe. The pupil is fufceptible of conflderable con¬ traction and dilatation, and the iris is often of a golden or flne red colour. The noftrils are two openings at the extremity of the fnout, for receiving the fenfation of iinell. 6 149 Tl he trunk is that part of the body which reaches Anatomy from the nape to the vent. It is fcaly, annulated, tu-°* Serpents, berculated, or wrinkled ; and comprehends the back, Ades, belly, anus, organs of generation, and fcales. The Trunk, back is the upper part of the trunk, commencing at the 24' nape and terminating immediately above the vent. In Bark, molt Ipecies it is rounded, but in fome carinated or fur- . 25 rowed. 'The Ades are the lateral portions of the trunk, from the extremity of the jaws to the vent. The belly, Belly, or abdomen, is the loxver part of the body, from the head to the tail, the want of a diaphragm precluding a breaft. The anus is an opening, ufuaily tranfverfe, Anus7 placed at the extremity of tjie lower lurface of the trunk, forming the line of demarcation between the lat¬ ter and the tail, and affording a paffage to the liquid and folid excrements. The penis of the male, and the ovary of the female, are alfo Atuated in this common vent, from which they are extended only during the 28 feafon of pairing. The fcales, properly fo called, are Scales, round, oval, oblong, and attenuated at the extremities, rhomboidal, fmooth, or carinated. The broad undivid¬ ed plates on the belly and head, are termed 'cuta, and the 1 mailer or divided plates beneath the tail, are cal- led fquamcc fubcaudales or fcut ell a, fubcuudal fcales or platelets. The tail is attenuated, obtufe, fquare, in the form of Tail!9 a triangular pyramid, flattened or compreffed at the Ades. As ferpents have neither limbs nor breaft, the ftruc- Skeleton, ture of their Ikeleton is much lefs complex than that of quadrupeds. The bones of the head are from eight to ten. The Ikull, which is fometimes flat and 1'ometimes convex, is very hard and eompaCt, and exhibits four principal futures, which are with difficulty feparated. The bones of the trunk conftft of a feries of vertebra, incafed in one another, and articulated with the ribs. The caudal vertebrae are difpofed in the fame manner, and provided with fimilar proceffes ; but they are un- eonnedted with ribs, and gradually diminilh in fize as they approach to the end of the tail. In molt quadru¬ peds, the joints m the back-bone feldom exceed thirty or forty ; whereas in ferpents they often amount to 145, from the head to the-vent, and 25 more from that to the tail. The number of thefe joints mult give the back-bone a furpriAng degree of pliancy, which is ftill increafed by the manner in which one is locked into the other. In man and quadrupeds, the flat fur faces of the bones are laid one again u the other, and bound tight by flnews ; but in ferpents the bones play one within the other, like ball andfocket, fo that they have free motion in every direction. The remarkable ftrength and agility, manifclted by Mufcles. ferpents, depend on the vigorous mufcles with which they are provided. Several of thefe are inferted along and beneath the Ikull, and about the upper and lower jaws. Four, which are denominated lateral, have their origin behind the head, and delcend, by each fide, to the extremity of the tail. Each vertebra has alfo its correfpohding intercoftal mufcle, which ferves the fame purpofes as in other animals. The internal organs, or vifeera of individuals of this viftera, order of animals, nearly correfpond to thofe of others, and, confequently, need not long detain us. f he brain is divided into five fmall portions, which ^ are round, and fomewhat elongated. The two firlt are biain° placed *50 Anatomy of Serpents. 34 Tracheal artery. 35 Lungs. 3 <5 Ocfophagus, 37 Stomach. 35 Heart. O P H I O L O G Y. t9, Inteftxnal canal. 40 Kidneys. 41 External fenfes. 44 Sexual u- 43 Oviparou: placed between tbe eyes, and give origin to tire olfac¬ tory nerves ; other two are lituated in the middle region of the tkull j and the laft, which is a little farther back, appears to be the commencement of the fpinal marrow. The tracheal artery, compofed of diftinft and cartilagi¬ nous rings, has its origin at the top of the gullet, and communicates with the lungs, under the heart. The lungs are not lobed, but conlift of a cellular and mem¬ branous fubftance, abundantly furnilhed with blood vel- • fels. The oefophagus is formed of a fmgle membrane, extends to the orifice of the ftomach, is of an equal di¬ ameter throughout, and fufceptible of an extraordinary degree of dilatation. The ftomach, which is of a largei capacity, is formed of two concentric tunics, which clofely adhere, and which are internally covered with folds or wrinkles. The heart has two ventricles, and is fmall in proportion to the fize of the body. As the cir¬ culation of the blood is independent of the lungs, the animal is enabled to remain for a conftderable time un- xier water. It cannot, however, make this element its conftant refidence ; becaufe occafional fupplies of fiefh air are necefiary to preferve in its blood thofe qualities which are neceffary to motion and vitality. In ferpents, therefore, as Avell as in viviparous quadrupeds, refpira- tion is eflential to life. I his function they do not pei- form by a rapid fucceflion of alternate dilatations and contractions of the lungs } but, having this vifeus lemaik- ably large in proportion to their bodies, they are able to fill it with a confiderable provifion of air ; and as they expire very flowly, fome time will elapfe before they are obli°-ed to infpire again. The inteftinal canal is nar¬ row^ finuous, and internally divided by many tranfverfe partitions. The kidneys are particularly large, and compofed of fmall continuous glands, blended with ex¬ cretory veftels. re That animals of the ferpent kind poilels the ute ot the five external fenfes, can fcarcely admit of diipute. We have indeed remarked, that moft of the fpecies ap¬ pear to want an external auditory paffage 5 but.it is certain that they are often direfted to birds, by liften- ing to their notes 5 and many indicate a degree of fenfi- bifity to the founds of mufical inftruments. Their fenfe of fmell, with a few remarkable exceptions, is neither very aftive nor acute •, but, in moft, that of fight is quick and penetrating. The foft and nervous textuie of the tongue and palate.would induce a fufpicion, that they enioy the fenfe of tafte in a pre-eminent degree } yet, as they generally fwallow their food in large portions, they feldom avail themfelves of the delicacy of thefe organs. Bein°r unprovided with feet, hands, or feelers, their fen e of touch is probably very imperfea ; and even when thev twine very clofely round an objeft, the mterpo 1- tion of their feales will render their feeling of its furface vague and obtufe. „ ,, 1 - The fexual union of ferpents ufually takes place in the funny days of fpring,is very clofe and ardent, and varies in duration from an hour to feveral days, according to the fpecies, but terminates w ithout any permanent attachment. The females of fome are Oviparous, and of others vivi¬ parous. The eggs of the former vary in refpeCl of fize, colour, and number, according to the fpecies and con- ftitution of the individual •, and.they are depofited,. not in continuous fucceflion, but at intervals, and fometimes *vith the appearance of much fuffering on the part 01 the female. Sergerus relates, that he faw a female fnake, Plwfiology after twitting herfelf, and rolling on the ground in an01 Serpents. unufual manner, bring forth an egg. He immediately took her up, and facilitated the extruiion of thirteen more, the laying of all which confumed an hour and a half; for, after depofiting each, the retted for fome time. When he remitted his afliftance, the procefs w as more flow and difficult 5 and the poor animal feemed to re¬ ceive his good offices with gratitude, which ftie exprefled' by gently rubbing her head againft his hands. I he mother never hatches thefe eggs, but leaves them expo- fed in fome warm fituation, as in holes w ith a iouthern afped, on dry fand, under mofs or foliage, on a dung¬ hill, near an oven, &c. The outer covering of the egg is a thin compaa membrane, and the young ferpent is fpirally rolled in its albuminous liquid. T he viviparous Viviparous, fpeeies differ confiderably, both with refpea to their periods of geftation, and' the number of their offspring. Thus, vipers which go about three months with young, generally breed twice a-year, and produce from twenty to twenty-four, while the blind-worm, which is pregnant about a month, brings forth fometimes feven, and fome¬ times ten at a birth. When young ferpents are hatched or produced, they are abandoned to the refourees of their own inftina, and often periffi before they have acquired fufficient experience to ffmn the fnares which are laid for them by quadrupeds, birds, and reptiles. . 45 In regard to the different Itages of growth of the dif- Growth, ferentfpecies,little precife information feems to have been obtained: and, though fome arrive at a very large fize, their dimenfions have, no doubt, been much exaggera- ted. The young of the viper, at the moment of partu- Size, rition, meafures from twelve to fifteen lines ; and twm or three years elapfe before they are capable of repro¬ ducing their kind. Adanfon how'ever concludes, from ocular obfervation, that the largeft .ferpent in Senegal may meafure from forty to fifty feet in length, and from a foot to a foot and a half in breadth. Leguat affures us, that he faw one in Java, that was fifty feet long. Carli afferts, that they grow to upwards of forty feet. Mr Wentworth, a gentleman who had large concerns in the Berbices, informs us, that he one day lent out a fol- dier, with an Indian, to kill wild fow l for the table ; and they accordingly w'ent fome miles from the fort. In puriuing their game, the Indian, who generally marched before, beginning to tire, went to reft himfelf on the fallen trunk of a tree, as he fuppofed it to be } but, when he was juft going to fit down, the huge monfter began to move, and the poor favage, perceiving that he had approached a Boa, dropped down in an agony. The foldier perceiving what had happened, levelled at the ferpent’s head, and by a lucky aim {hot it dead. He continued his fire, however, until he was affured that the animal was killed ; and then going up to refeue his com¬ panion, he found him killed by the fright. The animal wras brought to the fort, and was found to meaiuie thirty-fix feet. Mr W. caufed the fkin to be fluffed, and fent it as a prefent to the Prince of Orange. We are told, that when Regulus led his army along the banks of the Bagrada, in Africa, an enormous ferpent difputed his paffage acrofs the river. If we can give credit to Pliny, this reptile was 1 20 feet long, and had deftroyed many of the foldiers, when it was overcome in turn by the battering engines. Its fpoils were carried OPHIOLOGY. 47 Voice. 4S Maffes of food. 49 jCapability pf abfti- phyfiology to Rome, and the general was decreed an ovation for his of Serpents. fuccefs. The fkin was preferved for years after in the 1 capital, where Pliny fays that he faw it. In regard to voice, fome ferpents are apparently filent, and others have a peculiar cry ; but hiding is the found which they moft commonly utter, either as a call to their kind, or a threat to their enemies. In countries where they abound, they are generally fi- lent in the middle of the day ; but, in the cool of the evening, they iffue from their retreats with continued hidings. The mafles of food which ferpents are enabled to fwallow, would appear quite miraculous, did Ave not re¬ ded on the lax ftrudure of their jaws, their power of crulhing their viftims, and the vifeid humour, or faliva, which lubricates the crude morfel in its paffage down an extenfile osfophagus. In fpite of all thefe circumdances, the quantity of.aliment is fometimes fo voluminous, that it flicks in the gullet, when only partly immevfed in the ftomach, and the animal lies flretched and nearly mo- tionlefs, in its retreat, till the fwallowed portion be di- gefted, and the extruded half introduced, to undergo the fame procefs. But, though ferpents thus occafionally gorge themfelves with food, as their blood is colder than that of moft other terreftrial animals, and circulates flowly, their powers of digeltion are feeble and tardy, fo that they can endure weeks, and even months of ab- flinence. Nay, fo tenacious are they of the vital prin¬ ciple, that they exift and grow in mephitic marfties, continue to breathe, for a confiderable time, in the ex- haufted receiver of an air-pump, and frequently exhibit fymptoms of life after one part of the body has been fevered from the other. Vipers are often kept in boxes, for fix or eight months, without any food whatever ; and there are little ferpents fometimes fent to Europe from Cairo, wrhich live for feveral years in glafles, and never eat at all. The natural term of the exiftence of ferpents, is not accurately known ; but it has been conje&ured, that fome of the larger kinds may complete a century. The firft failure of their ftrength is the almoft immediate forerunner of their diflblution ; for, when deprived of the requifite elafticity of frame to fpring on their prey, and of the requifite force to combat their enemies, they flirink into their recefles, and die of hunger, or are eafily devoured by the ichneumon, ftork, and other powerful aflailants. In the more northerly and temperate regions of the globe, the ferpent tribes, towards the end of autumn, fall into a ftate of torpor, more or lels profound, according to the greater or lefs intenfity of the cold ; and in this condition they remain, nearly life- lefs, till the approach of fpring reanimates their flif- fened frame. Soon after its refufeitation, the ferpent Works itfelf out of its old epidermis, by rubbing itfelf againft the ground, or by wedging itfelf between any two fubftan- ces that are fufficiently elofe to each other. The exu¬ viae come off entire, being loofened firft about the head j and are always found turned infide out. It is fome time before the feales acquire a fufficient degree of hardnefs to defend the animal againftr external in- jury; and, during this interval, it generally confines it¬ felf to its retreat. \gi. SO 5* fyberna- 5* | Renewal ikin. Generic and Specific Rxpofition of the Order* Gen. i. Crotalus. Ratt/e-Snuke. Scuta on the abdomen, feuta and fquamse beneath the tail, rattle terminating the tail. The animals of this genus inhabit America, where they prey on the fmaller birds, lizards, and infe&s. They are furnilhed with poifonous fangs, and have a broad head, covered with large feales. " Their fnout is obtufely rounded. Banded Ratt/e-Snake, Common Rattle-Snake, or Boi- quira.—The characters are, 167 abdominal, and 23 fub- caudal feuta. The ordinary length of this fpeeies is from three to four or five feet, and the greateft thiek- nefs that of a man’s arm. The prevailing colour is a yellowilh brown, marked with crofs and irregular bands of a deeper (hade, and two or three longitudinal ftripes from the head down the neck; the under parts are of a dingy brown, with many dulky variegations and frec¬ kles. The mouth is capable of great diftenfion. The tongue is black, (lender, bipartite, and inclofed in a kind of (heath, from which the fnake darts forth the double point, and vibrates it with great velocity. The rattle- fnake is viviparous, producing in June about twelve young, which, by September, acquire the length of about twelve inches. Thefe, it is faid to preferve from danger, like the viper in Europe, by receiving them in¬ to its mouth, and fwallowing them. In confirmation of this affertion, we (hall quote the words of M. de Beau- vois, who, during his refidence in America, bellowed particular attention on the hiftory of amphibious rep¬ tiles. “ Among the information which I endeavoured to obtain in my travels with refpeCl to ferpents in general, there was one point Avhich greatly excited my curiofity. Several perfons, and one among the reft to whom I owe a debt of gratitude for civilities and marks of friendlhip, which will for ever reft engraven on my heart, had in¬ formed me, that the female rattle-fnake concealed its young ones in its body ; that when they were alarmed by any noife, or by the approach of man, they took re¬ fuge in the body of their mother, into which they en¬ tered by her mouth. This faCl had been already afeer- tained with refpeCl to the viper of Europe ; but in con- fequence of the unfavourable and repulftve difpofitions infpired by this kind of reptile, and in order to render it ftill more hideous, an abfurd interpretation was given to this fad. It was pretended, that this ferpent eats its little ones after having given them birth. Curious to verify this fad related of the boiquira, I was conftant- ly occupied with this idea, and began to defpair of ever making the obfervation, when, at a moment in which I thought the lead of it, accident furniftied me the means. Having fallen Tick among the Indians, I found myfelf obliged to remain a few days with one of them in the neighbourhood of Pine-log. During my conva-- lefcence, I took a walk every morning, in the neigh¬ bourhood, and one day when I was following a pretty broad path, I perceived, at a diftance, a ferpent lying acrofs the road in the fun. I had a (tick in my hand, and drew near to kill it; but what was my furprife, when, in the moment that I was about to give the blow.,. the 53 Crotalus, 54 Generic characters* 55 Horriditt* 1^2 Crotalus. O P II I O L O G Y. tlie reptile perceived me, coiled up itfelf, and opened from various experiments reported in the Philofopliical Crotahs. * its large mOiith, into which live ferpents, which I had Tranfaflions, and other publications. A rattle-lnake of v~ not till then obferved, becaufe they were lying along about four feet long, being faftened to a flake, bit three its body,‘rulhed into the gulf which I had conceived dogs, the firll of which died in lefs than a quarter of a opened for xnyfelf. I retired to one fide, and hid my- minute the fecond, which was bitten a ibort time felf behind a tree. The reptile had crawled a few paces, afterwards, in about two hours, and the third, which but hearing no further noife, and not perceiving me, was bitten about half an hour afterwards, Ihowed the yi- flretched itfelf out afrelh. In a quarter of an hour the lible effcfts of the poifon in thre,e hours, and likewife young ones came out again. Satisfied'with this obferva- died. Other experiments were indituted y and laifly, tion, I advanced anew towards the animal, with intention in order to try it the fnake could poifon itlell, it was to kill it and examine the interior of its itomach : but provoked to bite a part of its own body, and actually it did not permit me to approach fo near as it did the expired in lefs than twelve minutes. Our limits "id ' fn-ft time, the young ones entered with dill greater pre- not permit us to enumerate various other indances of cipitation into their retreat, and the boiquira ded into the almod indantaneous effecls of this poifon, w hich is the grafs. My fatisfaftion and adonilhment were fo mod to be dreaded in hot weather, and when the animal great, that I did not think of following it.” _ is much irritated. The rattle-fnake, however, is rather ^ The rattle confids of a number of pieces, inferted in- afraid of man, and will not venture to attack him un¬ to each other, all alike in diape and fize, hollow, and lefs provoked. It motes flowly, for the mod part with of a thin, eladic, brittle fubdance, dmilar to the exte- its head on the ground, but if alarmed, it throws its rior part of the feuta. Their form is nearly that of an body into a circle, coiling itfelf, with the head ered in inverted quadrilateral pyramid, with the«porners round- the centre, and with its eyes darning in a terrific man¬ ed off. The fird piece, or that neared the body, may ner. In cafes of dight bites, the Indians ufually luck be conddered as a kind of cafe, which contains the three the wound. They have likewife recourfe to the juices lad vertebrae of the tail, on which it appeal’s to be of various herbs, and to the root at po/yga/afeneka ; b\\t moulded, and has three convex, circular elevations cor- thefe applications produce little effeft, without fcaridca- refponding with them ; the two lad of thefe elevations tion and ligatures. According to Dr Barton, the rude and are fitted tnto the two fird of the next piece j fo that of fimple praftice of the wedern fettlers, is, fird, to throw every piece except the lad, the fird only of the eleva- a tight ligature above the part into which the poilon lions is expofed to view, the two others being inclofed has been introduced, at lead as often as the cncum¬ in thofe of the following, in which they have room to dances of the cafe admit of fuch an application. 1 he play from fide to fide. Thefe feveral pieces have no wound is next fcarified, and a mixture of fait and. gun- mufcles, nerves, nor ligaments, nor are they connefted, powder, or either of thefe articles, feparately, laid on either with each other, or with the body of the ferpent the part. Over the whole is put a piece of the bark oi any otherwife than by the mode of infertion already de- juglans alba, or white .walnut-tree, which .afts as a feribed. Thus they derive no nouridiment from the blider. At the fame time, a deco.ftion or infufion.oi animal, and are merely an appendage which can have one or more dimulant vegetables, with large quantities no other motion than what is communicated to it by of milk, are adminidered internally : the doftor is, that of the tail. Thefe feveral pieces of which the rat- neverthelefs, of opinion, that, the beneficial effects ^of tie confids, appear to have been feparately formed, this mode of treatment are chiefly to be aferibed to tne Dr Van Meurs imagines them to be no other than the external applications. If the fang has penetrated a vein old epidermis of the tail, which, when its nouridiment is or artery, or attacked the region of the throat,, the bite intercepted by the new ficin formed beneath it, grows commonly proves fatal, and the patient expires in hard and brittle. Hence, he fuppofes, that whenever ful agony. “ Where a rattle-fnake, (lays Catefby), this part acquires a new Ikin, a new piece of the rattle with full force, penetrates with his deadly fangs, an is added to the former, which is thus detached from the pricks a vein, or artery, inevitable death enfues *, and vertebrae, and dioved farther from the tail. The num- that, as I have often fee.n, in lefs than two minutes, ber of thefe pieces, however, affords no certain criterion “ The Indians, (he continues), know their dediny the of the animal’s age, becaufe thofe which are mod re- minute they are bit 5 and, when they perceive it mor- mote from the tail, become fo dry and brittle, that they tal, apply no remedy, concluding all efforts in. vain.’ are very liable to be broken off and lod. Dr Barton, however, inclines to think, that this afler- The two principal fangs are placed without the jaws, tion diould be received with cOnfiderable limitation, and on a fe par ate bone, and the fmaller ones attached to that the application of ligatures, &c. even m cafes ap- mufcles and tendons. Thefe fangs may be couched, or parently the mod defperate, fhould not be neglected, raifed at the pleafure of the animal, and are furniflied According to Clavigero, the mod effectual method is with an opening near the root, and a flit towards the thought to be, the holding of the wounded part fome time point, fo that on prefling gently with the finger on the in the earth. But if the poifon be once received into fide of the gum, the poifon, which is yellowith, is per- the general mafs of the blood, it is almod needlefs to ceived to iffue from the hollow of the tooth, through the have recourfe to medicines. A confiderable degree of flit. The veficle which contains the poifon, is external- naufea is ufually the firfl alarming fymptom ) the pulle ly of a triangular form, and of a tendinous texture •, becomes full, flrong, and greatly agitated ; the whole internally, it is cellular j and its interior part termi- body fwells •, the eyes are fuffufed with blood ; a he- nates in a fmall du6l, communicating with the facculus morrhage frequently proceeds from the eyes, nofe, and which covers the perforated teeth. It is furniftied wdth ears ; large quantities of blood are fometimes thrown out a conflri&or mufcle, for the purpofe of exprefling its on the furfaee of the body, in the form of fweai ; the -contents. The virulence of the latter may be inferred teeth vacillate in their fockets j and the pains and groans OPHIOLOGY. Crotalm. 0f the unhappy fufferer too plainly indicate, that the mo- * 11 ment of diflolution is near at hand. The following remarkable cafe is related by Mr Heflor St John. A farmer was one day mowing with his negroes, when he accidentally trod on a rattle-fnake, which immediately turned on him, and bit his boot. At night, when he went to bed, he was attacked with fick- nefs, his body fwelled, and before a phyfician could be called in, he died. All his neighbours were furprifed at his hidden death *, but the body was interred without examination. A few' days after one of the fons put on the father’s boots, and, at night, when he pulled them off, he was feized with the fame fymptoms, and died on the following morning. The phyhcian arrived, and, unable to divine the caufe of fo lingular a diforder, fe- riouOy pronounced both the father and fon to have been bewitched. At the fale of the effects a neighbour purchafed the boots, and on putting them on, experien¬ ced the like dreadful fymptoms with the father and fon. A tkilful phyfician, however, being fent for, who had heard of the foregoing accidents, fufpe&ed the caufe, and by applying proper remedies, recovered the patient. The fatal boots were now carefully examined, and the two fangs of the fnake were difeovered to have been left in the leather, with the poifon-bladders adhering to them. They had penetrated entirely through, and both the fa¬ ther and fon had imperceptibly fcratched themfelves with their point in pulling off the boots. We are informed by Dr Barton, that a gentleman of Philadelphia had a large rattle-fnake brought to him alive, which he fo managed by a ftring, that he could eaflly lead it into, or out of a clofe cage. On the firft day, he fuffered this fnake to bite a chicken, w hich had teen allured to the mouth of the cage by crumbs of bread. In a few hours, the bird mortified, and died. On the fecond day, another chicken was bitten in the fame manner, and furvived the injury much longer than the firft:. On the third day, the experiment was made on a third chicken, which fwelled much, but, neverthe- left, recovered. On the fourth day feveral chickens were fuffered to be bitten, without receiving any injury. Thefe fimple experiments enable us to affign a reafon, why perfons who have aflually been bitten by the rat¬ tle-fnake, have fometimes experienced very inconfider- able, or no bad confequences from the wound *, they {hew in what manner many vegetables have acquired a reputation for curing the bites of ferpents, without our being obliged to impeach the veracity of thofe from whom our information is derived *, and laftly, they teach us the phyfiological fa .5S Camna. 66 Phrygia. O P H I O found wide enough to admit a body of the fize of a man’s head. The female depofits a confiderable number of eggs, which feldom exceed three inches in their greateft dia¬ meter, on the fand, or under leaves expofed to the fun’s rays. In fome diftri&s of Africa, the great boa is regard¬ ed as an objedt of veneration, and on the coaft of Mo¬ zambique, is worlhipped as a god. In a very interefting notice of this fpecies, communi¬ cated to us by John Corfe Scott, Efq. mention is made of a live individual, which was difcovered in a field, near the cattle, by fome labourers, in the province of Tipperah in Bengal. This fnake, wrhich meafured fifteen feet and three inches in length, and eighteen inches in circumference, was ftunned by repeated blows," before it could be fecured, and tied with cords to a long bamboo. It was pretty aftive after it wras untied, and made frequent darts at any perfon coming near it. On prefenting a long flick, it repeatedly feized and bit it with great fiercenefs. On difledlion, the heart was found to be of the fize of a flieep’s, with the communi¬ cation open between the two ventricles. The liver was fmall in proportion, being about the fize of the human pancreas, and, like it, divided into feveral lobes. The oefiphagus, from the mouth to the pylorus, meafured nine feet three inches, and its width was fufficient to admit a man’s head with eafe. The head was fmall, in proportion to the fize of the animal, the eyes w'ere dark and heavy, and the noftrils large ; but there was no per¬ ceptible organ of hearing. From the mechanifm of the jaws, they were capable of being diftended fo as to admit a fubftance or animal much thicker than the fnake itfelf. This mechanifm, and the abfence of grin¬ ders, obvioufly prove, that the food is fu-allowed entire, without maftication. In a gorged individual of this fpecies, Mr S. found an entire guana, and in another, a fawn, of a year old ; but the bones of thefe quadru¬ peds were unbroken. Spotted Boa.—250 abdominal, and 70 fubcaudal fcuta. Cinereous, with large, round, black fpots on the back, and fmaller ones, with white centres, on the fides, and oblong markings, interfperfed with fmaller variegations on the abdomen. Of a fize fcarcely inferior to the preceding, and of fimilar man¬ ners. It is a native of feveral parts of Soutli America, and, like other fnakes, occafionally eaten by the In¬ dians. , Ringed Boa.—265 abdominal, and 57 fubcaudal fcu¬ ta. General caft ferruginous, with large dark rings on the back, and blackifh kidney-lhaped fpots, with white centres on the fides. The aboma of feveral writers. Grows to a large fize, and is a native of South America, where it is treated with divine ho¬ nours. Canine or Green Boa.—203 abdominal, and 77 fub¬ caudal fcuta. Green, with crofs, waving, and white dorfal bands. It has its fpecific name from the form of its head, which refembles that of a dog. Though def- titute of poifon fangs, it inflitfls a fevere bite, when pro¬ voked. It meafures from four to twelve feet in lenoth inhabits South America, and is celebrated for^ its beautv. 67 LOGY, native of the Eaft Indies, and omitted by Linnaeus. White, with a cinereous tinge on the back, and the bo¬ dy marked with black lace-like variegations. Garden Boa.—290 abdominal, and 123 fubcaudal Hortulana. fcuta. Yellowifli gray, with brown variegations, re- fembling in form the parterres of an old-fafliioned gar¬ den, the body fomewhat comprefled, and the tides marked with cuneiform fpots. From two to three or four feet long, and native of South America. ^ Fafaated Boa.—233 abdominal, and 36 fubcaudal TL,fciata. fcuta. Yellosv, with dutky blue tranfverfe bands. The body fomewhat triangular, upwards of five feet in length, and five inches in the thickeft part. Native of India, and very poifonous. An individual of this fpecies was fent to Dr Ruffel, in a very languid and extenuated ftate. Being fet at liberty, it remained for fome time without moving, but foon began to crawl llowly towards a dark corner. A chicken being prefented, it feemed not to regard it, though the bird fluttered about it, and even refted a toe on its head. The chicken was then put on the fnake’s back, and clung fo faft with its toes, that, when attempted to be feparated, the fnake was dragged a lit¬ tle way, without offering to refent the infult. An hour after, the chicken was again prefented ; but the fnake ihe-wing no difpofition to bite, its jaws were forced afun- der, and the naked thigh of the chicken fo placed, that the jaws clofed on part of it. The chicken, when difen- gaged, (hewed immediate fymptoms of poifon : it couch¬ ed, purged once or twice, and was not able to fland. In the courfe of the firft ten minutes, after feveral inef- fe&ual efforts to rife, it refted its beak on the ground ; and the head was feized with paralyfis. After 15 mi¬ nutes, it Ihewed a frequent difpofition to lie down , but remained couched fome minutes longer. In 20 minutes, it lay down on one fide, and, convulfions fupervening foon after, it expired within 26 minutes. Viperme Boa.—209 abdominal, and 19 fubcaudal r7 69 fcuta. Gray, with a black waving dorfal band, edged ‘*erina‘ with white ; the fides fpotted with black. About a foot and a half in length, including the tail, which is only one inch and a half long. Native of India, where its bite is faid to produce a flow Availing of the fingers and toes. As, however, it has no fangs, and produces no deleterious effedts on brute animals : the truth of the re¬ port feems to be very queftionable. Lineated Boa.—209 abdominal, and 47 fubcaudal T. fcuta. Blackifh line, rvith white dotted, tranfverfe, meata arched lines, and Avhitifti abdomen. Slender, natNe of India, and highly poifonous. • Annulated Boa.—About tAvo feet in length, fome- ^nt^iata what ferruginous, Avith black rounded fpots, included * n “ a a' in rings, on the back, reniform ocellated fpots on the fides, and Avaving dulky variegations on the abdomen. Native of South America, figured by Madame Merian, and preferved in the Hunterian Mufeum, at Glalgow. I he other fpecies belonging to this genus are, eny- dris, ophryas, regia, murina, horatta, hipnule, contor- trix, and pa/pebrofa. Gen. 3. Coluber, Snale (properly fo called). Embroidered Boa.—A remarkably elegant pecies, 72 Coluber. Scuta, or undivided plates, under the abdomen j fquamae, pi, or broad alternate feales, under the tail. The lat-Chara 74 aems. 7$ Cacodee- O P H I O ter, although alternate, are reckoned by pairs j but, in many initances, the number is ftill undetermined, and it fometimes varies in the fame fpecies. This tribe contains about 200 fpecies, which greatly differ from one another in fize and habit. The poifon- ous forts, which conftitute about one-Hith of the whole, are generally dillinguifhed from the reft by their large, flattilh, fubeordate heads, and rather ihort bodies and tails *, whereas moft of the harmlefs fpecies have fmall heads, with longer bodies and tails in proportion. Lau- renti and Latreille have ranged the former under the genus Viper a, and the latter under that of Coluber: but Linnaeus, Daubenton, La Cepede, &c. include both forts under Coluber. This family of ferpents is widely diffufed over various quarters of the world. Common Viper.—146 abdominal fcuta, 39 fubcaudal fcales. Attains to the length of two, or even of three feet. The ground colour of the body is a dingy yellow, deeper in the female than in the male. The back is marked with rhomboidal, as the fides are with triangu¬ lar, black fpots. Its black belly, the greater thicknefs of the head, and the more abrupt termination of the tail, fufficiently diftinguifti it from the common fnake, with which it has been often confounded. The viper arrives at maturity in fix or feven years, and produces 10 or 12 live young at the end of the fe- cond or third. Mr White of Selborne killed and cut up a pregnant female, and found in the abdomen 15 young ones, about the fize of full grown earth-worms. No fooner were they freed from confinement, than they twifted and wriggled about, fet themfelves up, and gaped very wide when touched with a flick, exhibiting manift ft tokens of menace and defiance, though as yet no fangs were vifible, even with the help of glaffes,— That the young, for fome time after birth, retreat, when alarmed, into the mouth of the mother, feems to be a fat! fatisfadlorily afcertained. Vipers are capable of fupporting long abftinence, feed on reptiles, worms, and young birds, and become tor¬ pid in winter. Their poifon rarely proves fatal to man, and is moft fuccefTully counterafted by olive oil, tho¬ roughly rubbed on the wounded part. They are ufual- ly caught by wooden tongs, at the end of the tail, as, in that pofition, they cannot wind themfelves up to in¬ jure their enemy. Their flefh was formerly in high efteem, as a remedy for various difeafes, particularly as a reftorative. Of late years, however, it has loft much of its ancient credit, and is rarely prefcribed by modern practitioners. The common viper inhabits Europe and Siberia, and is by no means uncommon in Great Britain, being the only poifonous animal in the ifland, frequenting dry and ftony diftricts, and efpecially the chalky countries. It abounds in fome of the Hebrides, and is called adder by the Scots. This fpecies is fubject to feveral varieties, which we cannot flop to enumerate. The prefer, or black viper, refembles the berus, in almoft every particular but co¬ lour •, though Linnaeus, and other eminent naturalifts, rank it as a diftimt fpecies. American Black Viper.—About the length of the preceding, but much thicker, black, and remarkable for the largenefs of its head, which it diftends, with a horrid hifs, when irritated. Its bite is reckoned as dan- L O G Y. gerous as that of the rattlefnake. It is a native of Ca- Coluber, rolina, chiefly frequenting higher grounds. —v-—* Egyptian Viper.— 118 abdominal fcuta, and 22 fub- y "tl caudal fcales.. Somewhat ferruginous, Ipotted with ll>eia' brown $ whitifti beneath, with a ihort mucronated tail. Rather fmaller than the common fpecies. Imported in confiderable quantities to Venice, for the ufeofthe apo¬ thecaries in the compofition of theriaca, &c. Native of Egypt, and fuppofed by fome to be the afp of Cleo¬ patra 5 but it is very difficult to alcertain the true afp of the ancients. ^ Charajiun Viper.—Rufous, with the fnout acuminated CharaJU. above, and the body marked with ihort, fubconfluent, dufky, and tranfverfe ftreaks. Nearly allied to the common fpecies, and defcribed by Charas, a celebrated anatomift of ferpents in his day, but who contended, in oppofition to Redi, that the fymptoms caufed by the viperine bite, proceeded from what he termed the enra¬ ged fpirits of the creature, and not from the fuppofed poifonous fluid. Redi's Viper.—152 abdominal fcuta, and 32 fubcau- dal fcales. Of an iron brown colour with a quadruple tranfverfe feries of ihort, fubconfluent, brown ilreaks on the back. In other refpefts nearly allied to the com¬ mon viper, but faid to be more poifonous. It occurs in Auftria and Italy, and is the fort which Redi chiefly employed in his experiments relative to animal poi¬ fon. . 79 Afp.—155 abdominal fcuta, and 37 fubcaudal fcales. Jfu, Somewhat rufous, with roundiffi, alternate, duiky fpots on the back, and fubconfluent ones near the tail. A- bout three feet long, the head rather large, and cover¬ ed with fmall carinated fcales. Native of France, par¬ ticularly of the northern provinces of that country. It is very doubtful if this be the genuine coluber afpis (Lin.); and ftill more fo if it be the afp of the an¬ cients. go Greek Viper.—155 abdominal fcuta, and 46 fubcau- Lcbetimu, dal fcales. Gray, with a fourfold feries of tranfverfe fpots, thofe on the middle yellowiffi, and thofe on the fides dufky. Nearly a cubit in length, yery thick to¬ wards the middle, and the head large and deprefled. Inhabits Greece and the Grecian iflands. According to Forfkal, its bite proves fatal by inducing infuperable fleep. _ 8t Cerajles, or Horned Viper.*— 150 abdominal plates, Cerajles. and 25 fubcaudal fcales. Pale yellowiffi, or reddiffi brown, with a few round, diftant, or oblong fpots, of a deeper tinge, fcattered along the upper parts of the body, and the belly of a pale leaden hue. The two curved proceffes, fituated above the eyes, give the ani¬ mal a more than ordinary appearance of malignity. Its length varies from about 15 inches to two feet. It is found in many parts of Africa, efpecially affe&ing dry places, and fandy defects, and inflifting a dangerous wound on thofe who happen to approach it. 8a Horn-nofe Snake.— 127 abdominal plates, 3 2 fubcau- Nafieornit’ dal fcales. Olive brown, with blackiffi variegations, a row of pale dorfal fpots, furrounded by black, and a waving pale band on the fides. This fierce and forbid¬ ding fpecies, which has its denomination from two large and pointed proceffes on the tip of the nofe, is fuppofed to inhabit the interior parts of Africa. 83 Meg or Uenon. “ Having been always curious to obferve the means by which fume men command the opinions of others, I regretted that 1 was not at Rofetta, at the proceilion of the feait of Ibrahim, in which the convulfions of the Pfylli form the molt entertaining part, to the populace, of this religious ceremony. To make up for my lofs, I addrelTed myfelf to the chief of the left, who was keeper of the Okel or tavern of the Franks j I Hattered him j and he promifed to make me a fpectator of the exaltation of one of the Pfylli, as foon as he ihould have infpired him. From my curiofity he thought I was likely to become a profelyte, and he propofed to initiate me, which I accepted ; but when 1 learned that in the cere¬ mony of initiation, the grand mailer fpits in the mouth of the neophyte, this circumllance cooled my ardour, and I found that I could not prevail on myielf to fubmit to fuch a point of probation. I therefore gave my money to the chief, and the high prieft promifed to let me fee one of the infpired. “ They had brought with them feme ferpents, which they let loofe from a large leather fack in which they were kept, and by irritation made them eredl their bodies, and hifs. I remarked that the light was the principal caufe of their anger; for as loon as they were returned into the fack, their paflion ceafed, and they no longer endeavoured to bite. I hey had a particular quality, which was that when angry, the neck for fix inches below the head was dilated to the lize of one’s hand. I foon faw, that I had no greater reafon to dread the bite of thefe ferpents than their mailers had ; for having well remarked that the Pfylli, while they were threatening the animal with one hand, feized it on the back of the head with the other, I did the lame with one of the ferpents with equal fuccefs, though much to the indignation of thefe myfterious quacks.” We have likewife heard of people in Europe who allowed themfelves to be bitten by vipers, with im¬ punity, to the great allonilhment of the Ipedlators. They firll made the animal eat of a prepared palte, which clofed the apertures in the fangs, and thus pre- eluded the difeharge of the poifon. Serpentine Various and contradi&ory opinions, conjeftures, and poifon. fidlions, have been advanced relative to the nature, adlion, and cure of ferpentine poifon. Among the vul¬ gar errors connefled with this fubjecl, we may reckon the Jting, fixed in the ferpent’s tail, and the flowing of venom from the black forked tongue, and from the teeth in general. Towards the end of the 17th century, Ferdinand II. Grand Duke of Tufcany, invited Steno, Redi, and fome other eminent men of fcience, to his court, with a view to inveftigate the hiilory of this important phenomenon in tire animal economy. Redi, in particular, inllituted a great variety of experiments, and arrived at fome ufe- ful difeoveries. When he either caufed a living viper to bite a dog, or wounded the latter with the teeth of one newly dead, the event was the fame. If the bite was repeated, its effeft became weaker, and, at length was loll, the poifon contained in the veficle being ex- haufted. He obferved, that w hen the teeth of ferpents ■were extended to bite, they were moiflcned over with a certain liquor, and that when the veficle at the bafe Mifcellanr. was preifed, a drop of poifon flowed to the point of the ousObier- fang. When the poifon thus flowing from the veficle , 'l>‘ltl^ons' ^ was received in fofl bread, or a fponge, an animal bitten by the ferpent received no more harm from the wound than from the pinch of a needle, till after a few days, when the venom was fecreted afrelh but when an ani¬ mal was wounded with the point of a needle dipped in the poifon, it was tormented with the fame pains as if it had been bitten by the viper itlelf. Having preferved fome of this poifon in a glafs, and totally evaporated the moillure in the fun, when the refiduum was diluted with water, Redi found, to his great furprife, that it had the fame effedl as when recent. But the boldnefs of Jacob Sozzi, a viper charmer, excited the aftonithment of the learned. As they happened in the prince’s pre¬ fence to talk of the certain death which would attend the fwallowing of viperine poifon, Sozzi, confiding in his art, drank a confiderable portion of it without hefi- tation, and with the fame fafety as if he had drunk fo much water. This refult, which fo much llartled the grand duke and his philofophic affociates, was not unknown to the ancients, as may be inferredfrom thefe lines in Lucan. Noxia ferpentum ejl admifo /anguine pef is: Morfu virus habent et fatum dente minuntur, Pocu/a morte carent. The ingenious and indefatigable Fontana made no fewer than 6oco experiments on this interefling fubjedl. Of thefe, our limits will not permit us to enumerate the refults. In confequence, however, of his multiplied and perfevering refearches, wre are enabled to Hate, that this poifon is not fatal to all animals •, that it kills neither vi¬ pers, fnakes, blind-worms, fnails, nor leeches 5 that it adls very (lightly on tortoifes j that it is neither an acid nor an alkali-, thatit has no determined favour, and that it leaves in the mouth merely a fenfation of aftringency and ftu- por. It long retains its virulence in the cavity of the tooth, whether the latter be feparated or not from its focket; but when dried and kept in an expofed fitua- tion, it lofes its deleterious qualities in lefs than a year. Hence the propriety of caution in examining vipers that are fluffed or preferved in fpirits, and in making ufe of clothes that have been bitten by them. Fontana has alfo* proved that the poifon of the viper is not uniformly fa¬ tal except to very fmall animals, and that it is more dan¬ gerous to the larger forts, according to the quantity of virus fecreted, the frequency of the bites, the different- parts of the body on which they have been inflicted, and probably alfo, the higher temperature of the atmofphere. A fparrow dies in five or eight minutes, a pigeon in eight or twelve, a cat fometimes recovers, and a flieep very often j fo that a man has little reafon to dread the confequences of a Angle bite in the climate of Italy, and flill lefs fo in France or Great Britain. The hun¬ dredth part of a grain of poifon applied to a mufcle will kill a fparrow, whereas fix times that quantity are re¬ quired to kill a pigeon. According to this eflimate, about three grains fhould prove fatal to a man, and 12 to an ox. But the veficles of an ordinarily fized viper feldom contain more than two grains of poifon, and even that quantity is not exhaulled till after repeated bites. The poifon is of a gummy confiflency, and feems to aft by deftroying the irritability of the mufcular fibre, OPHIOLOGY. 163 Mlfcellane- fibre, and introducing into tlie fluids a principle of pu¬ pa* Obfer- trefadtion. It may be fwallowed with impunity, pro- , vat‘ons- i vided there be no wound in the mouth $ but if intro¬ duced into the blood, the molt violent and convulfive agonies enfue, the fanguiferous fyftem becoming coagu¬ lated, and the whole animal frame relaxed. Hence, powerful fudorifics, as the flefh of the viper itfelf, of fnakes and lizards, which contain a large proportion of ammoniacal foap, the volatile alkali, and its various preparations, with numerous plants which excite copious perfpiration, have been recommended, and often fuc- cefsfully ufed as antidotes, efpecially when their ex¬ hibition has been preceded by a tight ligature imme¬ diately above the wound, and by fcarification and cau- Itics. On the effects and cure of the poifon of fnakes, fome valuable obfervations and reflections occur in Dr Ruflell’s fplcndid work on Indian ferpents. The judicious au¬ thor remarks, that when the poifon is applied to brute animals, its progrefs is often fo very rapid as hardly to leave time for the operation of medicine, or the applica¬ tion of any means whatever, with a probability of fuc- cefs. When the. progrefs is flower, fhould the remedy be adminiflered before unequivocal fymptoms have re¬ moved all doubt of the poifon having taken cffeCt, re¬ covery may be afcribed to the medicine given, whilft, in reality, no malady cxifted ; and if deferred till doubts are removed, the remedy which, if applied in time might have proved efficacious, may be unjuflly regarded as ufelefs. Relides, it is well known that a bite of the moft noxious fnake does not conftantly prove fatal, and that even fome of the more tender animals, without the ufe of any remedy, recover in cafes where the fymptoms are apparently very formidable. Thefe fymptoms, in the bodies of different animals, are very much alike, and proceed nearly in the fame order of progreflion, though with different degrees of rapidity. The American Indians either fuck the wound, or ap¬ ply to it chewed tobacco, or make feveral incifions around it, which they fill with gunpowder, and then fire it off. During the progrefs of the cure they have likewife recourfe to feveral pounded and bruifed plants, as to fome of the fpecies of lachica, the root of prennn- thes alba, the Items and leaves of a fpecies of helianthus, and in defperate cafes the radical bark of the tulip-tree. In general they are partial to the ufe of the fyngenefious plants, and to the bark of the trunk and roots of va¬ rious trees. The experiments of Bernard de Juffieu, Lebeau, Son- nini, and Bofc, feem to have eftabliflied that, of all known remedies for the bite of the viper and the rattle- fnake, the moft efficacious are, the volatile alkali, or eau tie luce, with fudftion and fcarification of the recent wound, In addition to thefe methods of cure, we {hall quote the prefeription of Dr Mofeiey, who fpent 12 years in the Weft Indies. “ The bites and flings of all venomous animals are cured by the fame local means, which are very Ample if they were always at hand. The injured part muft be inftantly deftroyed or cut out. Deflroying it is the moil fafe, and equally certain ; and the beft application for that purpofe is the lapis infernalis, or butter of an¬ timony. Thefe are preferable to a hot iron which the ancients ufed, becaufe a hot iron forms a cruft, which adds as a defence to the under parts inftead of deftroying Mifcenanc. them. The lapis infernalis is much better than any other, as it melts and penetrates during its application. ' . The bitten part muft be deftroyed to the bottom, and where there is any doubt that the bottom of the wound is not fufficiently expbfed, butter of antimony fhould be introduced to it on the following day, as deep as pof- lible ; and inciflons ftiould be made to lay every part open to the adtion of thefe applications. BeJides de¬ ftroying, burning, or cutting out the part, incifions ffiould be made round the wound, to prevent the com¬ munication of the virus. The wound is to be drefl'ed for lome time with poultices, to afluage the inflamma¬ tion caufed by the cauftics •, and afterwards with acrid dreffings and hot digeftives to drain the injured parts. “ Where the above-mentioned cauflics cannot be procured, eorrofive fublimate, oil of vitriol, aquafortis, fpirit of fait, common cauftic, or a plafter made of quicklime and foap, may be applied to the wound. Gunpowder laid on the part and fired, has been ufed with fuccefs. When a perfon is bitten remote from any affiftance, he fliould make a tight ligature above the part until proper application can be made. The Spaidfli writers fay, that the habilla de Carthagena, or Carthagena bean, is a fpecific for poifonous bites taken inwardly. Dr Mofeiey then proceeds to ftate the ample tefti- mony of Ulloa in favour of this bean, which is found in great abundance in the Weft India iflands, under the name of antidote or cocoon antidote. “ I have been in¬ formed (adds he) by fome intelligent Indians, that any of the red peppers, fuch as bird pepper or bell pepper, or what is called Cayenne pepper, powdered, and taken in a glafs of rum, as much as the ftomach can pofiibly bear, fo as to caufe and keep up for fome time great heat and inflammation in the body, and a vigorous cir¬ culation, will flop the progrefs of the poifon of ferpents, even after its effefts are vifible ; and that the bitten part only afterwards mortifies and feparates, and that the patient, with bark, wine, and cordials, foon reco- vers-” . r3<) The naturalift who collcfts ferpents for the purpofe Preferva- of preferving them in his cabinet, fhould have recourfe t‘on ^er* to various precautions, which, though feveral of thempent8‘ are fufficiently obvious, are, at the fame time, too often neglefted. In general the hurtful forts are caught with the greateft fafety and dexterity by natives of the coun¬ try in which they abound. The want of the head in many of the larger fluffed fpecimens from Guiana, &c. renders them of little value in a feientific point of view, and is the refult of fuperfluous trouble to travellers who fend them to Europe in this mutilated condition. Col- leftors, therefore, ftumld carefully inftru£t their agents to preferve this part of the animal. As thefe larger fpecimens cannot eafily be prepared without an incifion in the {kin, it will be of confequence to make this inci¬ fion on the fide, beginning at the termination of the plates, and not cutting acrofs them, as is too often done* to the great prejudice of diftinft claffification. When the fkin is once ftripped, it may be carefully rolled up, and fluffed in the preparation room in the ufual manner. The fmaller fpecies of ferpents may be kept in pre¬ pared fpirits. Pure alcohol and fpirituous liquors, efpe- cialiy when not reduced by water, frequently afFeft the X 2 moft 164 O P H I O Mtfcellane- mofl; brilliant animal colours. Thus, in the ordinary 0tvatictiel ca^^net liquors, the fine red of the haemachate fnake » ^—7, degenerates into a dark brown, fcales of a bright green or blue become fomewhat pale, yellow always whitens, and orange changes to red or pale. White, brown, black, purple, mother of pearl, and metal-coloured fcales are not liable to change. The following is an approved recipe for preferving the various colours of ferpents entire. Take very pure fpring water, faturate it with alum, then mix with it about one-fifth of its bulk of very lim¬ pid fpirit of wine, pafs the mixture through a paper ftrainer, and keep the liquor well corked up in bottles, in fome cool and lhady fituation. Immerfe the animal which you wifh to preferve in a veffel filled with this liquor, and allow it to remain in it 24 hours. The vef- lei and its included liquor fhould be referved for this preliminary procefs. Then remove the reptile into a cylindrical veffel of fine glafs, filled to three-fourths of its height with the liquor above defcribed, and clofed LOG Y. with a glafs cover. Lute the latter with maftic and Mifcellane- hogs greafe } put the veffel on a ffielf that is Iheltered ous ?bf«- from heat and the folar rays 5 and at the end of two vatl0ns- months, if the maftic be dry, and you wilh the jar to 'r~J remain clofed, paint the luting with an oil colour; but if you intend to open it frequently, ufe only the hogs greafe. Reptiles may alfo be conveniently preferved accord¬ ing to the method indicated by Chauffer, in the Bulle¬ tin des Sciences, (for Prairial, year 10, N° 63.), without the previous trouble of preparing the Ikin. All that is required, is to {tuff the cavities with cotton, and to im¬ merfe the body in diftilled water, faturated with fuper- oxygenated muriate of mercury j and when it has fuf- ficiently imbibed the faline folution in all its parts, to allow’ it to dry {lowly in a well aired fituation, fcreened from the fun and duff. All the parts of the animal harden, and are thus defended from the voracity of in¬ fers, and corruption of every kind. EXPLANATION of PLATES CCCLXXI, CCCLXXII, CCCLXXIII, and CCCLXXIV. Fig. 1. Carinated Scale. — 2. Plain Scale. — 3. Tail of Coluber Snake. — 4. Tail of Boa. — 5. Fang or Tooth through which the poifon is conveyed. Fig. 6. The head of poifonous fnake furniffed with fangs, aa a a. Fig. 7. The head of innoxious fnake without fangs. — 8. Crotalus Horridus, Banded Rattle-Snake. — 9. Boa Conjlriffor. Fig. 10. Coluber Berus, Common Viper. — 11. - Cerajles. — 12. Laticaudatus, Colubrine Hydrus. — 13. Languya Nafuta, Snouted Langaya. — 14. Acrochordus Javanicus, Javan Acruchor- dus. Fig. 15. Anguis Corallinus, Coral Slow-worm. —* 16. Amphijbtzna Alba, White Amphilbaena. — 17. Fuliginous Amphif- baena. Fig. 18. Ceccilia Tentaculata, Eel-fliaped Csecilia. t INDEX. jicROCHOKDUS, characters and fpecies of, N° 116 Ana'omt/ of ferpents, 12—41 Anguis, characters and fpecies of, 119—126 Atnpliijhcena, characters, &c. 127—130 Asp, 79 B. Banded rattle-fnake, hiftory of, 55 Boa, characters, Ipecies, and hiftory of, 60—71 Black fnake, 93 Black-tailed rattle-fnake, 59 Blue and green fnake, 95 Canine boa, 65 Cerajles, 81 Crotalus, characters and fpecies of, 53—59 natural hiftory of, ib. Cobra de Capello, 84 Coluber, characters, fpecies, and hiftory of, 72—101 ConJlriBor boa, 61 Coach-whip fnake, N° 96 Cceciha, characters, &e. 132—135 D. Domejlic fnake, 100 E. Embroidered boa, 66 F. Fafdated boa, 68 Garden boa, 67 H. Horn-nofe fnake, 82 llydriis,characters and fpecies of, 106—112 I. Iridefcent fnake 105 Langaya, characters and fpecies, 114, 115 Lineated fnake, 102 M. Miliary rattle-fnake, 58 O. Ophiology, introduction to, > Ophiology, hiftory of, N° 2—-II writers on, ib. P. Phyjiology of ferpents, 42—52 Poifon of ferpents, 138 experiments on by Redi, ib. by Fontana, ib. cure of, ib. R. Rattle-fnake, characters^ fpecies, and hi- ftory of, 53-39 Kinged boa, 64 fnake, 92 Ruffellian fnake, 85 S. Serpents, anatomy of, 12—41 phyfiology of, 42—j2 worftiip of, 136 enchantment of, 137 poifon of, 138 prefervation of, 139 Striped rattle-fnake, 56 SpeElach r-v\7Vyivy OPHIOIiOGY FLATE CCCEXXZT. ■ ophiology: PLATE CCCLA A ///. ^//- OPHIOLOGY /VsJYV'J CCCJsXXZV » S'sy . / >0. Spectacle fnake, N° 84 Spotted boa, __ _ 63 Slow-warm, charaders and fpecies of, 119—126 common, 121 painted, 122 coral, 123 glafs, 124 OPHIOLOGY. Slow-xvorm, fnouted, N° 125 Jamaica, 126 V. Viper, common, 74 American black, 75 Egyptian, 76 Charafian, 77 Redi’s, 78 Viper, Greek, N° 80 horned, 81 water, 88 W. Water-fnahe, charaders and fpecies of, 106—112 Wood rattle-fnake, 37 O P H Ophioman- OPHIOMANCY, in antiquity, the art of making cy predidions from ferpents. Thus Calchas, on feeing II a ferpent devour eight fparrows with their dam, fore- °l)hir- , told the duration of the fiege of Troy : and the feven ’ coils of a ferpent that was feen on Anchifes’s tomb, were interpreted to mean the feven years that ./Eneas wandered from place to place before he arrived at Latium. OPHIORHIZA, a genus of plants belonging to the pentandria clafs, and in the natural method ranking un¬ der the 47th order, Stellatce. See Botany Index. OPHIOXYLON, a genus of plants belonging to the polygamia clafs, and in the natural method ranking with thofe of which the order is doubtful. See Botany T Index. Different OPHIR, a country mentioned in Scripture, from hypothefes which Solomon had great quantities of gold brought the fifing ^ome wh*ch he fent out for that purpofe ; but tion of11" 'where t0 its lituation is the great difficulty, authors Ophir. running into various opinions on that head. Some ^ have gone to the Weft, others to the Eaft Indies, and Hypothefis the eaftern coaft of Africa, in fearch of it.—Mr Bruce, of Mr the celebrated Abyffinian traveller, has difplayed much Bruce. learning and ingenuity in fettling this queftion of Bi¬ blical hiftory. To the fatisfadHon of moft of his readers, he has determined Ophir to be Sofala, a king¬ dom of Africa, on the coaft of Mofambique, near Zan- guebar (fee Sofala). His reafons for this determi¬ nation are fo generally known, that it would be im¬ proper to repeat them here at length j becaufe fuch as are not already acquainted with them may con- fult his book, which has been long in the hands of the public. He juftly obferves, that in order to come to a certainty where this Ophir was, it will be neceflary to examine what Scripture fays of it, and to keep precifely to every thing like defcription which we can find there, without indulging our fancy farther. V?, Then, the trade to Ophir, was carried on from the Elanitic gulf through the Indian ocean, id/y, The returns were gold, filver, and ivory, but efpecially f 1 Kings, ^ver f. ^d/y, The time of the going and coming of J-22. the fleet was precifely three years J, at no period more ^ 1 ^gs, or lefs. 2 chron Now, if Solomon’s fleet failed from the Elanitic ix. 2i, §UR to the Indian ocean, this voyage of neceffity nrnft have been made by monfoons, for no other winds reign in that ocean. And what certainly ftiows this ivas the cafe, is the precife term of three years in which the fleet went and came between Ophir and Ezion-gaber. Thefe mines of Ophir were probably what furniflied 3 O P H the Eaft with gold in the earlieft times : great traces of Ophir. excavation muft therefore have appeared. ' ^ But John dos Santos fays, that he landed at Sofala in the year 1586; that he failed up the great river Cuama as far as lete, where, always defirous to be in the neighbourhood of gold, his order had placed their convent. Thence he penetrated for about two hundred leagues into the country, and faw the gold mines then 3 working at a mountain called Afura. At a confi-Arguments derable diftance from thefe are the filver mines of Chi-in fuPPort coua j at botli places there is a great appearance of0* lt;“ ancient excavations \ and at both places the houfes of the kings are built with mud and ftraw, whilft there, are large remains of maffy buildings of ftone and lime. Every thing then confpires to fix the Ophir of Solo¬ mon in the kingdom of Sofala, provided it would necef- farily require neither more nor lefs than three years to make a voyage from Ezion-gaber to that place and Tar- ftiiflr and return. To eftabliffi this important fad, our author obferves, that the fleet or ffiip for Sofala, part¬ ing in June from Ezion-gaber (fee Ezion-gaber),. would run down before the northern monfoon to Mo¬ cha (fee Mocha). Here, not the monfoon, but the direflion of the gulf, changes; and the violence of the fouth-wefters, which then reign in the Indian ocean, make themfelves at times felt even in Mocha roads. The veflel therefore comes to an anchor in the harbour of Mocha} and here fhe waits for moderate weather and a fair wind, which carries her out of the ftraits of Babelmandel, through the few leagues where the wind is variable. Her courfe from this is nearly louth-weft, and flie meets at Cape Guardafui, a ftrong fouth-wefter that blows dircftly in her teeth. Being obliged to return into the gulf, ftie miftakes this for a trade-wind j be¬ caufe lire is not able to make her voyage to Mocha but by the fummer monfoon, which carries her no far¬ ther than the ftraits of Babelmandel, and then leaves her in the face of a contrary wind, a ftrong current to the northward, and violent fwell. The attempting this voyage with fails, in thefe cir- cumftances, was abfolutely impoffible, as their veflels went only before the wind : if it was performed at all, it muft have been by oars; and great havock and lofs of men muft have been the confequence of the feveral trials. At laft, philofophy and obfervation, together with the unwearied perfeverance of man bent upon his own viewTs and intereft, removed thefe difficulties, and (bowed the mariners of the Arabian gulf, that thefe periodical ■winds. V O P H . [ 166 ] O P H Ophir. -wincls, wlilch in the beginning they looked upon as in- vjncjj3ie barriers to the trading to Sofala, when once underftood, were the very means of performing this voyage fafely and expeditioufly. The veffel trading to Sofala failed from the bottom of 'the Arabian gulf in fummer, with the monfoon at north, which carried her to Mocha. There the mon¬ foon failed her by the change of the dire&ion of the gulf. The fouth-well winds, whicli blow without Cape Guardafui in the Indian ocean, forced themfelves round the cape fo as to be felt in the road of Mocha, and make it uneafy riding there. But thofe foon changed, the Aveather became moderate, and the veffel, we fup- pofe in the month of Auguft, was fafe at anchor un¬ der Cape Guardafui, where was the port whicli, many years afterwards, was called Protnontorium Aroma- tum. Here the fliip was obliged to flay all Novem-^ ber, becaufe all thefe fummer months the wind fouth of the cape was a ftrong fouth-wefter, as hath been before faid, direftly in the teeth of the voyage to So¬ fala. But this time was not loft •, part of the goods bought to be ready for the return was ivory, frankin- cenfe, and myrrh •, and the fliip Avas then at the princi¬ pal mart for thefe. Our author fuppofes, that in November the veffel failed Avith the Avind at north-eaft, Avith Avhich flie would foon have made her voyage : but off the coaft of P*Ielinda, in the beginning of December, fhe there met an anomalous monfoon at fouth-weft, in our days fir ft obferved by Dr Halley, Avhich cut off her voyage to Sofala, and obliged her to put into the fmall har¬ bour of Mocha, near Melinda, but nearer ftill to Tarftiifli, Avhich aa'C find here by accident, and which we think a ftrong corroboration that avc are right as to the reft of the voyage. In the annals of Abyflinia, it is faid that Amda Sion, making Avar upon that coaft in the 14th century, in a lift of the rebellious Moorifli vaffals, mentions-the chief of Tarfliifli as one of them, in the very fituation Avhere avc have noAV placed him. Solomon’s veffel, then, Avas obliged to ftay at Tar¬ fliifli till the month of April of the fecond year. In May, the Avind fet in at north-eaft, and probably carried her that fame month to Sofala. All the time flie fpent at Tarfliifti Avas not loft, for part of her cargo was to be brought from that place •, and flie probably bought, befpoke, or left it there. From May of the fecond year, to the end of that monfoon in October, the veffel could not ftir •, the Avind Avas north-eaft. But that time, far from being loft, Avas neceffary to the traders for getting in their cargo, which we (hall fuppofe was ready for them. The ftlip fails on her return, in the month of Novem¬ ber of the fecond year, with the monfoon fouth-weft, which in a very feAv weeks Avould have carried her into the Arabian gulf. But off Mocha, near Melinda and Tarfliifli, fhe met the north-eaft monfoon, and Avas obli¬ ged to go into that port, and ftay there till the end of that monfoon 5 after which a fouth-wefter came to her relief in May of the third year. With the May mon¬ foon flie ran to Mocha within the ftraits, and was there confined by the fummer monfoon bloiving up the Ara¬ bian gulf from Suez, and meeting her. Here {he lay till that monfoon which in fummer blows northerly from Suez, changed to a fouth-eaft one in October or 4 November, and that very eafily brought her up into the EJanitic gulf, the middle or end of December of the third year. She had no need of more time to com¬ plete her voyage, and it was not poflible fhe could do it in lefs. Such is a very fliort and imperfeft abftraft of our author’s reafons for placing Ophir in Sofala. If it excite the curiofity of our readers to confult his work, it w’ill anlwer the purpofe for which avc have made it. We are noAV to give another ingenious conjedture Another concerning the fituation of Ophir and Tarftiilh, Avith hypothefis* which we have been favoured by Dr Doig, the learn¬ ed author of Letters on the Savage State, addreffed to Lord Karnes. This refpedlable Avriter holds that Ophir was fome- where on the Aveft coaft of Africa, and that Tarftiilh was the ancient Bietica in Spain. His effay is not yet publiftied; but he authorizes us to give the follow¬ ing abltradl of it: “ The firft lime that Ophir, or ra¬ ther Aufir, occurs in Scripture, is in Gen. x. 29. Avhere the facred hiftorian, enumerating the fons of Joktan, mentions Aulir as one of them.” According to his account, the defeendants of thofe 13 brothers fettled all in a contiguous fituation, from Melba (the Mocha of the moderns) to Sepharah, a mountain of the eaft, Mofes, as every one knoAVs, denominates countries, and the inhabitants of countries, from the patriarch from whom thofe inhabitants defeended. In delcribing the courfe of one of the branches of the river of paradife, the fame Mofts informs us that it encompaffed the Avhole land of Havilah, &c. which abounded Avith fine gold, bdellium, and the onyx fione and this land had its name from Havilah, the 1 2th fon of the patriarch Joktan. Ophir or Aiifir Avas Havilah’s immediate elder brother ; and of courfe the defeendants of the former, in all probability, fixed their habitation in the neigh¬ bourhood of thofe of the latter. If, then, the land of Havilah abounded Avith gold and precious ftones, the land of Ophir undoubtedly produced the very fame articles. Here then we have the original Ophir \ here was yj^ found the primary gold of Ophir 5 and here lay the nal Ophir Ophir mentioned in Job xi. 24. But as navigation not the Avas then in its infant ftate, the native land of gold mentioned by Job muft have been much nearer home ,v]ut'u’ than that to which the fleets of Solomon and Hiram made their triennial voyages. That feveral countries on the fouth-eaft coaft of Africa abounded Avith gold long after the era of Job, is evident from the teftimony of Herodotus, Strabo, Diodorus Siculus, Ptolemy, Pom- ponius Mela, &c. $ but that in thefe countries the Gphir of Solomon could not be fituated, is plain, becaufe his {hips in the fame voyage touched at Tarfliilh, which lay in a very different quarter. The Abyffinian traveller has placed this regia mrri- fera in Sofala on the eaftern coaft of Africa, nearly- oppolite to the ifland of Madagafcar, This hypotbelis Avas current a hundred years before he Avas born $ but I am perfuaded (fays our author) that it is not tenable. The Ophir of Solomon, in Avbatever part of Africa it lay, muft have been well knoAvn, prior to his reign, both to the Phoenicians and the Edomites. Thefe people na¬ vigated that monarch’s fleet, and therefore could be no ftrangers to the port whither they were bound. That Ophir. 6 the fitua- tion muft be afcer- tained by difcovering that of Tarfliifli. f Pf. xlviii. 7. Ixxii. 10. $ Gen. ii. 26. H If. xxiii. pajjim. Tlie origi¬ nal Tar- Ihifli, where fituated. O P H [ 1 it was in Africa is certain ; and that it was on the well: coad of that immenfe peninfula, will appear more than probable, when we have afcertained the fituation of Tarfhifh, and the ufual courfe of Phoenician naviga¬ tion. To thefe obje&s, therefore, we diall now direft our inquiries. “ Javan, tlie fourth fon of the patriarch Japhet, had four fons, Elidia, Tarjhijh, Kittim, and Dodanim or Rodanim •, among whofe ‘ defcendants were the ifles of the Gentiles divided.’ The city of Tarfus on the coad of Cilicia, at once afcertains the region colonized by the defcendants of Tarfhifh. Rut as much depends upon determining the pofition of this country, I fhall endeavour (fays the Dodtor) to fix it with all poflible precifion. “In the fird place, I mud beg leave to obferve, that there is not a fingle paffage in any ancient author, facred or profane, that fo much as alludes to any city, didrift, canton, or country, of the name of Tarfhifh in the eadern parts of the world. The defcendants of Javan, of whom Tarfhidi was one, are agreed on all hands to have extended their fettlements towards the north-wed, i. e. into Ada Minor, Italy, and Spain. The inhabitants of Tarfhifh are everywhere in Scrip¬ ture faid to be addifted to navigation and commerce, in which they feem to have been connefted with the Tyrians and Phoenicians f, who were always faid by the Jews to inhabit the ides of the fea. Indeed, in He¬ brew geography, all the countries towards the north and wed, which were divided from Judea by the fea, were called the ides of the fea J. Thus Ifaiah : ‘ The bur¬ den of Tyre. Howl ye fhips of Tarfhifh, for it is laid wade, fo that there is no houfe, no entering in : from the land of Chittim it is revealed unto them. Be dill ye inhabitants of the ide, thou whom the merchants of Zidon, that pals over the fea, have replenifhed.’ The land of Chittim was Macedonia, and often Greece, from which every one knows that the dedruftion of Tyre came ; and that Tardiifh was not an unconcerned fpec- tator of that dedruftion, is obvious from the fame pro¬ phet, who proceeds to fay ]| : ‘As at the report con¬ cerning Egypt, fo fhall they be forely pierced at the re¬ port concerning Tyre. Pafs over to Tarfhidi 5 howl ye inhabitants of the ide. Is this your joyous city ?’ It appears likewife from Ezekiel xxvii. 12. that Tarfhifh was the merchant with whom Tyre traded for filver, iron, tin, and lead, and that this trade was carried on in fairs. “ From all thefe padages, it feems to be evident, that the defcendants of Tarfhifh fettled on the wedern coad of Afia Minor \ that thefe people were addifted to navigation and commerce ; that in the courfe of their traffic they were connefted with the Tyrians and Phoenicians 5 that the commerce they carried on confid¬ ed of filver, iron, tin, and lead \ that the people of Tar- fhidr were connefted with Kittim and the illes of the Gentiles, which are confededly fituated toward the north and wed of Judea. “ But led, after all, a faft fo fully authenticated fhould dill be called in quedion, I fhall add one proof more, which will place the matter beyond the reach of doubt and controverfy. “ When the prophet Jonah intended to dee from the prefence, of the Lord, in order to avoid preaching at, Nineveh, let us fee where the peevifh deferter embark- 67 ] O P H ed (Jonah i. 3.). “ And Jonah rofe up to dee unto Ophir. Tarfhidi, from the prefence of the Lord, and went down ' 1 v ■ to Joppa 5 and he found a fiiip going to Tarfhifh, and he paid the fare thereof, and went down into it, to go with them into Tardiifh, from the prefence of the Lord.’ Every body knows that Joppa or Japhah flood upon the fliore of the Mediterranean j of courfe the fugitive pro¬ phet had determined to go to fome very diilant region weftward, and by that means to get as far from Nineveh as poffible.” g Having thus proved to a demonftration, that the This not original Tarfhidi was a region on the weftern coaft of the Tar- Afia Minor, where either the patriarch of that name, 01 i0“ or fome of his immediate defcendants, planted a colo¬ ny, it remains to determine whether this w7as aftually the country from which Solomon imported the vail quantities of filver mentioned by the facred hiftorian. That it was not, our author frankly acknowledges ; and therefore, fays he, we muft look out for Solomon’s Tar- diiffi in fome other quarter of the globe. ^ To pave the way for this difeovery, he very juftly The name obferves, that it has at all times been a common prac-of one tice to transfer the name of one country to another, in country confequence of fome analogy or refemblance between them. It has likewife often happened, that when a commodity was brought from a very diftant country by a very diftant people, the people to whom it was import¬ ed have taken it for granted that it was produced in the region from which it was immediately brought to them. Of the truth of this pofition no man acquainted -with the Greek and Roman poets can for a moment entertain a doubt. Hence the AJJyrium amomutn of Virgil, and the AJfijrium malabathrum of Horace, though thefe ar¬ ticles were the produft not of Aflyria but of India. The Jews, who were as little acquainted with foreign countries as the Greeks and Romans, had very probably the fame notions with them refpefting articles of com¬ merce y and if fo, they would undoubtedly fuppofe, that the filver fold by the merchants of Tarffiifh was the produft: of that country. When this miftake came to be difeovered, they very naturally transferred the name Tarjhijh from the country of the merchants to that of the articles which they imported. Let us now, fays our author, try if we cannot find out where that country was. It has been already ftiown, by quotations from Ifaiah and Ezekiel, that the merchants of Tarlhiffi traded in the markets of Tyre with filver, iron, lead, and tin. To thefe authorities, xve ffiall add another from Jere¬ miah : “ Silver (fays that prophet) fpread into plates is brought from Tarffiilh.” “ But in Spain (continues our learned diflertator), all thofe commodities were found in the greateft abundance. All the ancient authors who deferibe that region dwell with rapture on its filver mines. This faft is too generally known to need to be fupported by authorities. Spain was then the region which furniffied Solomon’s traders with the immenfe mafs of filver he is faid to have imported. This was, one might fay, the modern Tarffiiffi ; and indeed both Jofephus and Eufebius are pofitive that the pofterity of Tarlhiffi aftually peopled that country. If this was an early opinion, as it certainly w'as, the Jews would of courfe denominate Spain from the patriarch in que- ftion. I have ffiown above, that the inhabitants of Tar- fhiffi O P H [ Ophir. fliifli were ftri&ly connefled with the Kittim, or Gre- cians : J {hall here produce an authority which will prove to a demonftration that the Kittim had extend¬ ed their commerce into that part of Africa now called Barbary. “ The prophet Ezekiel, (xxvii. 6.) defcribing the fplendour and magnificence of Tyre, tells us, ‘ that the company of the Afhurites made her benches of ivo¬ ry, brought from the ifies of Kittim.’ In the firft place, I muft obferve, that there is probably a fmall error in the orthography of the word Aftiurim. This term is everywhere in Scripture tranflated Aflyrians, which tranilation is certainly juft. But how the Affyrians could export ivory from the ifles of Kittim, and fa- fliion it into benches for the Tyrian mariners, is, in my opinion, a problem of no eafy folution. T-he fadft is Aftiurim ftiould be Alherim, that is, the company of the men of Aftier. The tribe of Aftier obtained its inheritance in the neighbourhood of Tyre ; (fee Jofli. xix. 28.). ‘ And Hebron, and Rehob, and Ham- mon and Canah, unto Zidon the great.1 The compa¬ nies of the tribe of the Alherites then, and not the Afhurim, were the people who manufactured the bench¬ es in queftion. “ Be that as it may, the ivory of which the imple¬ ments were formed was imported from the ifies of Kittim, that is, from Greece and its neighbourhood. Thefe ifiands, it is certain, never produced ivory. They muft therefore have imported it from fome other ■country •, but no other country, to which the Greeks and their neighbours could have extended their com¬ merce, except the north of Africa, produced that com¬ modity. The conclufion then is, that the maritime ftates of Afia Minor, Greece, and probably the He- trufcans on the weft coaft of Italy, carried on a gain¬ ful commerce with Spain and Barbary at a very early periods “ We have now feen that the original Tarftiifli on the coaft of Afia Minor did not produce the metals im¬ ported by Solomon’s fleet; that no Tarftiifti is to be found in the eaftern parts of the globe j that the Tar- ftiifh we are in queft of was undoubtedly fituated fome- where towards the weft of Judea : we have ftiown that the mercantile people of Afia Minor, Greece, and pro¬ bably of Italy, aftually imported fome of thofe articles from the coaft of Africa •, we have hazarded a con- jefture, that Spain was the modern Tarftiifti, and that very country from which Solomon imported his filver, and the Tyrians their filver, iron, tin, and lead. Let us now make a trial whether we cannot exhibit fome internal proofs in fupport of the hypothefis we have above adopted. “ The ancients divided Spain into three parts, Bae- tica, Lufitania, and Tarraconenfis. Baetica is the mo¬ dern Andalufia. It ftretched along the Fretum Hercu- leum, or Straits of Gibraltar, to the mouth of the Gua- dalquiver. This region is thought by fome to have been the Elyfian fields of the poets. The river Baetis, which divides it, is called Tarte£us by Ariftotle, Stefi- chorus, Strabo, Paufanias, Steph. Byzant. and Avianus. Here too we have a city and a lake of the fame name. But Tarteffus is pofitively the very fame with Tar- ram colledled their gold in the courfe of their voyage ftiifli. The Phoenicians, by changing fchin into than, fomewhere on the coaft of Africa, beyond the Cape, made it Tartifti. The Greeks manufactured the reft, for the following reafons: Had they found the golden fleece 168 ] 0 P H by changing Tavtifti into Tartis, and in procefs of time Oplar. into TagTus-o-ej. That the Phoenicians actually changed fchin into thuu is certain ; for Plutarch tells us, in the life of Sylla, that in their language an ox was cal¬ led thor, which is, no doubt, the fame with the Hebrew fhor. ... . 10 “ From this deduction, it appears highly probable atxarfliififi leaft, that the Spanifti Baetica was originally called Tar-Spanith Jhifh. Indeed this fimilarity of names has operated fo^setica. powerfully on the learned Bochart, and on fome other moderns of no mean figure, that they have pofitively affirmed, as Jofephus had done before them, that the patriarch Tarftiifti actually fettled in that country. This I fliould think not altogether probable 5 but that his defcendants who fettled on the coaft of Afia Mi¬ nor colonized Baetica, and carried on an uninterrupted commerce to that country, along with the Phoenicians, for many centuries after it was peopled, and that from the circumftances above narrated, it was denominated Tarjhijh, are fa&s too palpable to admit of contradic¬ tion. “ Let us now fee whether this Bretica, where I have endeavoured to fix the fituation of the Tarftiifti of the Scriptures, was aftually furniftied with thofe articles of commerce which are faid to have been imported from that country. To enlarge on this topic would be alto¬ gether fuperfluous. Diodorus Siculus, Strabo, Polybiu^, Pliny, Solinus, and, in one wrord, all the Greek and Ro¬ man hiftorians who have mentioned that region, have unanimoufty exhibited it as the native land of filver, iron, and tin : to thefe, contrary to the opinions of the cele¬ brated modern traveller, they likewife add gold in very large quantities.” Our author having thus afcertained the fituation of Tarftiifh, proceeds to prove, by a mafs of evidence too large for our infertion, that the Edomites and Ty¬ rians had doubled the Cape, and almoft encompafled Africa, long before the era of Solomon. Then refer¬ ring to 1 Kings, chap. ix. and x. 2 Chron. viii. ix. 2 Kings xxii. and 2 Chron. xx. he obferves, that from thefe authorities it appears indubitable, that the fleets of Solomon and Hiram failed from Eloth and Ezion- geber 5 that the voyages to Ophir and Tarftiifti were exactly the fame, performed at one and the fame time, by the very fame fleet •, which muft neceflarily have en- compaffed the peninfiila of Africa before it could ar¬ rive at the country of Tarfliifti. This being the cafe, the traders might eafily enough colleft the gold on th& coaft of Guinea, or on what is now vulgarly called the Gold Coajl. The ivory they might readily enough pro¬ cure on the Barbary coaft, oppoftte to Tarftiifti. In Africa, too, they might hunt apes, monkeys, baboons, &c. \ and peacocks, or rather parrots, and parroquets, they might furprife in the forefts which abounded on the coaft:. In Spain, filver, iron, lead, and tin, were, one may fay, the native produce of the foil. Even at this early period, the Phoenician navigators had difcovered the Cafliterides or Scilly ifiands, and Cornwall 5 and from that region, in company with the merchants, may have fupplied them with that rare commodity. “ I have fuppofed that the navy of Solomon and Hi- O P H [ 169 ] O P H Ophir. fleece at Sofala (a), or any part of tlie coaft of Afri- ca, they would have chofen to return and unlade at Eloth or Ezion-geber, rather than purfue a long and dangerous courfe, quite round Africa, to Tarlhifh j to which laft country they might have fhaped their courfe much more commonly from Zidon, Tyre, Jop¬ pa, &c. But being obliged to double the Cape in quell: of fome of thofe articles which they were en¬ joined to import, they pulhed onward to Tarfhilh, and returned by the Pillars of Hercules to Tyre, or perhaps to Joppa, &c. Their next voyage commen¬ ced from one or other of thele ports, from which they diredled their courfe to Tarlhifti: and having taken m part of their lading there, they afterwards coafted round Africa, and lo arrived once more at Eloth or Ezion-geber. “ Let us now attend to the fpace of time in which thefe voyages were performed. We are told exprefs- ly (2 Chron. ix. 21.) that once every three years came the fhips of Tarfhith, &c. This is exadlly the time one would naturally imagine neceflary to per¬ form fuch a dillant voyage, at a period when naviga¬ tion was Hill in its infancy, and mariners feldom ad¬ ventured to lofe light of the coaft. Of this we have an irrefragable proof in the hillory of a voyage round the very fame continent, undertaken and aecomplifh- ed in the very fame fpace of time, about two centuries after. “ We learn from Herodotus, lib. ii. cap. 149. that Nechus, one of the latter kings of Egypt, whom the Scripture calls Pharaoh Necho, built a great number of ftu’ps, both on the Red fea and the Mediterranean. The fame hiftorian, lib. iv. cap. 42. informs us, that this en terprifing monarch projected a voyage round the conti¬ nent of Africa, which was actually accompliflied in the fpace of three years. In the condudt of this enterprile, he employed Phoenician mariners, as Solomon had done before him. Thefe, we may fuppofe, were aflifted in the courfe of this navigation by charts or journals, or at lead by traditional accounts derived from their ancef- tors : ‘ Thefe navigators (fays the hiftorian) took their departure from a port on the Red fea, and failing from thence into the fouthern ocean, and, in the beginning of autumn, landing on the coaft of Africa, there they fowed fome grain which they had carried out with them on board their veflels. In this place they waited till the crop was ripened ; and, having cut it down, they pro¬ ceeded on their voyage. Having fpent two years in this navigation, in the third they returned to Egypt, by the Pillars of Hercules. Thefe mariners, adds the author, reported a fa6t, which, for his part, he could by no means believe to be true ; namely, that in one part of their courfe their lhadows fell on their right; a circum- ftance which gives confiderable weight to the truth of the relation.’ “ Let it now be obferved that Phoenician mariners navigated the fleet of Solomon : the fame people con¬ duced that of Necho : the fleet of Necho fpent three years in the courfe of its voyage ; that of Solomon did the fame in its courfe about two centuries before : Vol. XV. Part I. the fleet of Necho failed from a port on the Red lea ; Ophir. that of Solomon took its departure from Eloth or *v'~— Ezion-geber, fituated on the fame fea : the fleet of ihe former returned by the Pillars of Hercules ; that of the latter, according to the hypothelis, purfued the very fame route. Such a coincidence of fimilar cir- cumftances united with thofe adduced in the preced¬ ing part of this article, feem to prove almoft to a demonftration, that the navy of Hiram and Solo¬ mon performed a voyage round Africa, in that age, in the fame manner as that of Necho did two centuries after. “ Upon the whole, I conclude, that the original. Ophir, which is really Aufir or Aufr, was fituated on the fouth of Arabia Felix, between Sheba and Havilah, which laft was enepmpaffed by one of the branches of the river of Paradife : that the name Ophir, i. e. Aufr, was, in confequence of its refemblance, in procefs of time transferred to a region on the coaft of Africa ; and that from it firft Afer and then Africa was deno¬ minated : that the primitive Tarfhilh was Cilicia, and that the Jews applied this name to all the commercial ftates on the coaft of Afia Minor, and perhaps of Italy, there being ftrong prefumptions that the Tyrrhenians were colonifts from Tarfhifti ; that Beetica, and per¬ haps fome other regions of Spain, being planted with colonies from Tarlhifti, like wife acquired the name of Tarlhifti; that the Tyrians were ftriclly connected with the merchants of Tarlhifti in their commercial enter- prifes •, that Tarlhifh was certainly fituated wertward from Judea, Phoenicia, &c. •, that no other country in the weftern quarters produced the commodities import¬ ed by the two kings, except Spain and the oppofite coafts ; that this country, in thofe ages, produced not only filver, iron, tin, and lead, but likewife gold in great abundance ; that the merchants of Kittim import¬ ed ivory, of which the Alherites made benches for the Tyrians •, which commodity they mull have purchafed on the coaft of Barbalry, where the Jews and Phoenici¬ ans would find the fame article ; that Tarfhifti being fi¬ tuated in Spain, it was impoflible for a fleet failing from Eloth, or Ezion-geber, to arrive at that country with- t£ out encompafling Africa j that of courfe the fleet in Ophir fitu- queftion did adlually encompafs that continent ; that ated on the the Ophir of Solomon mull have been fituated fome- coaft where on the coaft of Africa, to the weft of the Cape, becaufe from it the cqurfe to Tarlhifti was more eligible Cape, than to return the fame way back to Ezion-geber.” Our author fupports this conclufion by many other arguments and authorities, which the limits preferibed us will not permit us to detail ; but perhaps the ar¬ ticle might be deemed incomplete if we did not Ihow how he obviates an objeftion that will readily occur to his theory. “ If the original Ophir was feated on the coaft of Arabia Felix, and the modern region of the fame name on the weft coaft of Africa, it may be made a queftion, how the latter country came to be denominated from the former ? Nothing (fays our au¬ thor) can be more eafy than to anfwer this queftion. An objec- The practice of adapting the name of an ancient country tion an- Y to iwered. (A^ ^at Sofala oppofite to the ifland of Madagafcar was Ophir, was an ancient conjeflure. See Bochart- chan. 1. xi. cap. 27. p. 160. 4to, O P I [ r Ophir t0 a newly difcovered one, refenabling the other in ap- Opillion Pearance? in fituation, in figure, in diftance, in the na- — ' ture of the climate, produflions, &e. has ever been fo common, that to produce inftances would be altoge¬ ther fuperfluous. The newly difcovered region on the eoaft of Africa abounded with the fame fpecies of com¬ modities by which the original one was diftinguifhed ; and of courfe, the name of the latter was annexed to the former. Whether Mr Bruce’s hypothefis, or Dr Doig’s, re- ipefling the long-difputed fituation of Solomon’s Ophir, be the true one, it is not for us to decide. Both are plaufible, both are fupported by much ingenuity and uncommon erudition $ but we do not think that the arguments of either writer furnifii a complete con¬ futation of thofe adduced by the other. Sub judice lis ejl. OPHIRA, a genus of plants belonging to the o£tan- dria clafs. See Botany Index. OPHITES, in Natural Hjldnj, an old term em¬ ployed to denote a mineral, of a dutkv green ground, fprinkled with fpots of a lighter green, otherwife called Jerpentine. See Mineralogy Index. Ophttf.s, in church hiftory, Chritlian heretics, fo called both from the veneration they had for the ferpent that tempted Eve, and the worfhip they paid to a real ferpent: they pretended that the ferpent was Jefus Chrift, and that he taught men the knowledge of good and evil. They diftinguithed between Jefus and Chrijl: Jefus, they faid, was born of the Virgin, but Chritt came down from heaven to be united with him ; Jefus was crucified, but Chrift had left him to return to heaven. They di¬ ftinguithed the God of the Jews, Avhom they termed Jaldabaoth, from the fupreme God : to the former they afcribed the body, to the latter the foul of man. They had a live ferpent, which they kept in a kind of cage ; at certain times they opened the cage door, and called the ferpent : the animal came out, and mounting upon the table, twined itfelf about fume loaves of bread ; this bread they broke and diftributed it to the company, who all killed the ferpent : this they called their Eu- charijl. OPHRYS, Twyblade ; a genus of plants be’ong- ing to the gynandria clafs ; and in the natural method ranking under the 7th order, Orchidece. See Botany Index. OPHTHALMOSCOPY, a branch of phyfiogno- my, which deduces the knowledge of a man’s temper and chara&er from the appearance of his eyes. OPHTHALMIA, in Medicine, an inflammation of the eye or of the membranes which invert it; efpecial- ly of the adnata, or albugineous coat. See Medicine N° 174. OPIATES, medicines which are adminiftered to procure fleep, whether in the form of eleffuaries, drops, or pills. OPINION is that judgment which the mind forms of any propofition for the truth or falfehood of which there is not fufficient evidence to-produce faience or ab- folute belief. That the three angles of a plane triangle are equal to two right angles, is not a matter of opinion, nor can it with propriety be called an objeH of the mathemati¬ cian’s belief: he does more than believe it 5 he knows it to be true. When two or three men, under no temp- o ] O p o tation to deceive, declare that they were witneffes of an Opinion uncommon, though not preternatural event, their tefti- II mony is complete evidence, and produces ablblute be- , 0Porto- liefm the minds of thofe to whom it is given ; but it does not produce fcience like rigid demonftration. The faH is not doubted, but thofe who have it on report do not know it to be true, as they know the truth of pro- pofitions intuitively or demonitrably certain. When one or two men relate a ftory including many circum- ftances to a third perfon, and another comes who pofi- tively eontradi&s it either in whole or in part, he to whom thole jarring teftimonies are given, weighs all the circumftances in his own mind, balances the one againft the other, and lends an aflent, more or lefs wa¬ vering, to that fide on which the evidence appears to preponderate. I his afient is his opinion refpefting the facts of which he has received fuch different ac¬ counts. Opinions are often formed of events not yet in being. Were an officer from the combined armies, which are juft now * befieging Valenciennes, to come into the ^Julyiypj. room where we are writing, and tell us that thofe armies are in good health and high fpirits 5 that every Ihot which they fire upon the fortrefs produces feme effect; and that they have plenty of excellent provifion-, whilft: the befieged are perilhing by hunger ; we fliould abfo- lutely believe every faff which he had told us upon the evidence of his teftimony ; but we could only be of opi¬ nion that the garrifon muft foon furrender. In forming opinions of this kind, upon which, in a great meafure depends our fuccels in any purfuit, every circumitance ffiould be carefully attended to, and our judgments guided by former experience. Truth is a thing of fuch importance to man, that he (liould always purfue the belt methods for attaining it ; and when the objeH eludes all his refearches, he fhould remedy the difap- pointment, by attaching himfelf to that which has the ftrongeft refemblance to it ; and that which moft re- fembles truth is called probability, as the judgment which is formed ol it is termed opinion. See Probabi¬ lity. OPIUM, in the Materia,Medica, is an infpiffated juice, obtained from the capfule of the white poppy, partly of the refinous and partly of the gummy kind, and poffeffing alfo a narcotic principle. See Materia Medica, N° 612. OPOB ALSAMUM, in the Materia Medica, Opo- balfum, or balm of Gilead, a refinous fubftance obtained from a fpecies of Amyris. See Chemistry, N° 2472, and Materia Medica, N° $07. OPOCALPASUM, Opocarbasum, or Apocal- PASUM 5 a gummy refinous fubftance, which has a ftrong refemblance to liquid myrrh, and which in the time of Galen was mixed with myrrh. It was difficult, accord¬ ing to this writer, to diftinguifti the one from the other unlefii by their effedrts, the former being of a poifonous nature, which frequently produced lethargy. OPOPONAX, in the Materia Medica, is a gummy refinous fubftance brought from the Eaft Indies. See Materia Medica, N° 455, OPORTO, or Porto, a flourifhing city and fea- port of Portugal, in the province of Entre-Douero-e- Minho, with a bifhop’s fee. Nature has rendered it al- moft impregnable ; and it is juftly celebrated for the ftrength of its wines, large quantities of which are ex- , ported o p o i; i Oporto ported to Britain, and on this account all red wines ei- O un ther from Spain or Portugal are denominated pert wines. j^Un' . After the earthquake at Lifbon in the year 1755, the trade of this city increafed rapidly, before which memo¬ rable period its population did not exceed 20,000 5 but it is now computed at upwards of 40,000. Oporto is fituated on the declivity of a mountain, near the river Douero, which forms an excellent and commodious har¬ bour ; and is about 147 miles north by eaft of Lifbon. W. Long. 8. 21. N. Lat. 41. 10. OPOSSUM, in Zoology, a fpecies of didelphis. See Didelphis. OPOUN, one of the Navigators Iflands, of which there are ten in number, firft difeovered by Bougain¬ ville, and fo called by hirrij becaufe the inhabitants do not pafs from one village to another but in canoes. This and the other iflands lie in 140 fouth latitude, and from 1710 to 1730 longitude weft from Paris, accord¬ ing to Peroufe. Here the fugar cane is to be met with growing fpontaneoufly j but it is faid to contain lefs of the faccharine fubftance than what is produced in the Weft Indies. TL he men are poflefled of uncommon ftrength, and tatow their bodies in fuch a manner, that, although almoft naked, they have the appearance at a little diftance of being clothed. Ferocity and treachery are chara&eriftic marks of this people, of which the un¬ fortunate Peroufe had but too foon a melancholy proof, 11 out of 60 of his crew having been murdered by them, although received at firft with an air of good humour* T his ought to ferve as a caution to future na¬ vigators, not to place implicit confidence in the appa- OPT , PFICS, from oTcrcfioit, to fee, is that fcience which f # confiders the nature, the compofition, and the definition. mo^on 5—the changes .which it fuffers from the adtion of bodies —the phenomena of vifion, and the in- flruments in which light is the chief agent. HISTORY. Sect. I. Diftoveries concerning the Refra&ion of Light. TRefradtion THOUGH tfie ancients made few optical experiments, theTn-t0 tllcy. heverthelefs knew, that when light paffed through *ients; luedia of difterent denfities, it did not move in a ftraight line, but was bent or refraEed out of its original di¬ rection. This was probably fuggefted to them by the appearance ol a ftraight rod partly immerfed in water j and accordingly we find manyqueftions concerning this and other optical appearances in the works of Ariftotle. Archimedes is faid to have written a treatife on the ap¬ pearance of a ring or circle under water, and therefore could not have been ignorant of the common phenomena of refradtion. The ancients, however, were not only ac¬ quainted with thefe more ordinary appearances, but alfo with the production of colours by refraCtion. Seneca fays, that if the light of the fun fliines through an an¬ gular piece of glafs, it will fhow all the colours of the 71 ] OP T rent kindnefs of thefe favages, which is frequently the Opourt difmal prelude of ruin and deftruCtion. Among thefe II. fell the celebrated naturalift Lamanon} fee Lama- , NON. v’ OPPENHEIM, a town of Germany, in the lower palatinate of the Rhine, and capital of a bailiwick of the fame name j feated on the declivity of a hill near the Rhine. E. Long. 8. 20. N. Lat. 49. 48. OPPI ANUS, a poet and grammarian of Anazarba in Cilicia, in the fecond century. He compofed a poem of hunting, and another of fiftiing, for which Antoni¬ nus Caracalla gave him as many golden crowns as there were verfes in his poems; they were hence called Op~ plait's golden verfes.. He died in the 30th year of his age. OPPIL ATION, in Medicine, the aft of obftrufting or flopping up the pafiage of the body, by redundant or peccant humours. This word is chiefly for obftruCtions in the lower belly. OP i ALIVE MOOD, in Grammar, that which ferves to exprefs an ardent defire or wifh for fomething. In moft languages, except the Greek, the optative is only exprefled by prefixing to the fubjunClive an adverb of wiihing ; as utinam, in Latin •, pint a Dieu, in French ; and would to God, in Englifh. OPTIC angle, the angle which the optic axes of both eyes make with one another, as they tetid to meet at feme diftance before the eyes. Optic Axis, the axis of the eye, or a line going through the middle of the pupil and the centre of the eye. I C S. rainbow. Thefe colours, he fays, are falfe, fuch as are Hi (lory, feen in a pigeon’s neck when it changes its pofition j —-v—^ and of the fame nature, he fays, is a fpeculum, which, without having any colour of its own, aflumes that of any other body. It Appears, alfo, that the ancients were not ig-norant of the magnifying power of glafs globes filled with water, though they do not feem to have 3 been acquainted wflth its caufe •, and the ancient engra- and the vers are fuppofed to have uftd a glafs globe filled with »iagn'fying water to magnify their figures. This indeed feems evi- of dent, from their lenticular arid fpherical gems of rock8 * S ° ^ cryftal which are ftill preferved, the effeCl of which, in magnifying at leaft, could fdarcely have efcaped the no¬ tice of thofe who had often occafion to handle them ; if indeed, in the fpherical or lenticular form, they were not folely intended for the purpofes of burning. One of thefe, of the fpherical kind, of about an inch and a half diameter, is preferved among the foflils pre- - fented by Br Woodward to the univerfity of Cam¬ bridge. The firft treatife of any confequence written on the Refraction fubjeCt of optics, was by the celebrated Ptolemy. The firft treated treatife is now loft ; but from the accounts of others, Wefcientifical" find that he treated of aftronomical refraftions. Thejy by Pt0“ firft aftronomers were not aware that the intervals be-16™7* tween ftars appear lefs near the horizon than near the meridian j but it is evident that Ptolemy was atvare of this circumftance, by the caution which he gives to allow Y 2 fomething His hypo- fun and moon. OPT fomething for it, upon every recourfe to ancient obfer- vations. Ptolemy alfo advances a very fenfible hypothefis to thefis con- account for the greater apparent fize of the fun and ceming the moon when feen near the horizon. The mind, he fays, horizontal judges of the fize of obje&s by means of-a preconceived idea of their diftance from us: and this diftance is fan¬ cied to be greater when a number of objects intervene j which is the cafe when we fee the heavenly bodies near the horizon. In his Almageft, however, he afcribes this appearance to a refra&ion of the rays by vapours, which adually enlarge the angle fubtended by the lu¬ minaries. The nature of refra&ion was afterwards confider- ed by Alhazen an Arabian writer; infomuch that, having made experiments upon it at the common fur- 6 face between air and water, air and glafs, water and Difcoveries glafs 5 and, being prepoffeffed with the ancient opinion of Alhazen. 0f cryfinllme orbs in the regions above the atmofphere, he even fufpeded a refradion there alfo, and fancied he could prove it by aftronomical obfervations. Hence this author concludes, that refradion increafes the alti¬ tudes of all objeds in the heavens ; and he firll; advan¬ ced, that the fiars are fometimes feen above the horizon by means of refradion, when they are really below it. This obfervation was confirmed by Vitellio, B. Walthe- rus, and by the excellent obfervations of Tycho Brahe. Alhazen obferved, that refradion contrads the vertical diameters and diftances of the heavenly bodies, and that it is the caufe of the twinkling of the liars. But we do not find that either he, or his follower Vitellio, fub- jeded it to menfuration. Indeed it is too fmall to be determined except by very accurate inftruments, and therefore we hear little more of it till about the year 1500, when great attention was paid to the fubjed by Bernard Walther, Mseftlin, and Tycho Brahe. Alhazen fuppofed that the refradion of the atmo¬ fphere did rot depend upon the vapours, but on the dif¬ ferent tranfparency 5 by which, as Montucla conjec¬ tures, he fneant the denfity of the grofs air contiguous to the earth, and the ether or fubtile air that lies be¬ yond it. We judge of diftance, he fays, by comparing the angle under which objeds appear, with their fup¬ pofed diftance ; fo that if thefe angles be nearly equal, and the diftance of one objed be conceived greater than that of the other, it will be imagined to be larger. He alfo obferves, that the Iky near the horizon is always imagined to be further from us than any other part of the concave furface. Roger Bacon afcribes this account of the horizontal moon to Ptolemy ; and as fuch it is examined, and objeded to by B. Porta. In the writings of Roger Bacon, we find the firft di- Itind account of the magnifying power of glaffes ; and it is not improbable, that what he wrote upon this fub¬ jed gave rife to the ufeful invention of fpedacles. He fays, that if an objed be applied clofe to the bafe of the larger fegment of a fphere of glafs, it will appear magnified. He alfo treats of the appearance of an ob¬ jed through a globe, and fays that he was the firft who obferved the refradion of rays into it. Of Vitellio. Vitellio, a native of Poland, publilhed a treatife of ?i70. optics, containing all that was valuable in Alhazen. He obferves, that light is always loft by refradion 5 but he does not pretend to eftimate the quantity of this lofs. He reduced into a table the refult of his experk I c s. ments on the refradive powers of air, water, and glafs, Hiftory. correfponding to different angles of incidence. In his '•’■’■"V’"-' account of the horizontal moon he agrees exadly with Alhazen. He afcribes the twinkling of the ftars to the motion of the air m v'hich the light is refraded ; and to illuftrate this hypothefis, he obferves, that they twinkle ftill more when viewed in water put in motion. He alfo Ihows, that refradion is neceflary as rvell as re- fledion, to form the rainbow j becaufe the body which the rays fall upon is a tranfparent fubftance, at the fur- face of which one part of the light is always refleded and another refraded. But he feems to confider re¬ fradion as ferving only to condenfe the light, thereby enabling it to make a ftronger impreffion upon the eye. This writer alfo makes many attempts to afeertain the law of refradion. He likewife confiders the foci of glafs fpheres, and the apparent fize of objeds feen through them : though upon thefe fubjeds his obfervations are inaccurate. It is fufficient indeed to fhow the ftate of knowledge, at that time, to obferve, that both Vitellio, and his mafter Alhazen, account for objeds appearing larger when feen under water, by the circular figure of its furface ; fince, being fluid, it conforms to the figure of the earth. • g •Contemporary with Vitellio was Roger Bacon, a man of Roge* of extenfive genius, who wrote upon almoft every Bacon. branch of fcience j yet in optics he does not feem to have made any conliderable advances. Even fome of the moil abfurd of the opinions of the ancients have had the fandion of his authority. He believed that vifual rays proceed from the eye *, becaufe every thing in na¬ ture is qualified to difeharge its proper fundions by its own powers, in the fame manner as the fun and other celeftial bodies. In his Specula Mathematical he added fome obfervations of little importance on the refradion of the light of the ftars 5 the apparent fize of objeds ^ the enlargement of the fun and moon in the horizon. In his Opus Majus he demonftrates, what Alhazen had done before, that if a tranfparent body interpofed be¬ tween the eye and an objed, be convex towards the eye, the objed Avill appear magnified. ^ From this time, to that of the revival of learning inOfMaur*. Europe, we have no treatife on optics. One of thelycus. firll who diftinguilhed himfelf in this way was Mauro-I575- lycus, teacher of mathematics at Meflina. In two works, entitled Theoremata Lucis et U?nbrce, and Dia- phanoTum Partes, &c. he demonftrates that the cryftal- line humour of the eye is a lens that colleds the rays of light iffuing from the objed, and throws them upon the retina, where is the focus of each pencil. From this principle he difeovered the reafon why fome people were Ihort-fighted and others long-lighted } and why the for¬ mer are relieved by concave, and the others by convex, glafles. O # JQ While Maurolycus made fuch advances towards the Difcoveries d-fcovery of the nature of vifion, Baptiila Porta of Na- of B. Porta, pies invented the camera obfeura, which throws ftill Bom 1445. more light on the fame fubjed. His houfe was reforted I5I5* to by all the ingenious perfons at Naples, whom he formed into an academy offecrets ; each member being obliged to contribute fomething ufeful and not generally known. By this means he was furnilhed with materials for his Magia Naturalis, which contains his account of the camera obfeura, and which was publilhed, as he in¬ forms us, when he was not quite 15 years old. He alfo gave ■ Hiftory The law of refradlion difcovered. 16 $1- iz Opinions of Bei'caites and Leib¬ nitz on this fubjedt. OPT gave the firfl: hint of the magic lantern ; which Kircher ; afterwards improved. His experiments with the camera obftura convinced him, that vifion, as Ariftotle fuppo- fed, is performed by the intromiffion of fomething into the eye, and not by vifual rays proceeding from the eye, as had been formerly imagined by Empedocles ; and he was the firtt who fully fatisfied himfelf and others upon this fubjeft. The refemblance indeed between experi¬ ments with the camera obfcura and the manner in which vifion is performed in the eye, was too ftriking to efeape the obfervation of a lefs ingenious perfon. But when he fays that the eye is a camera obfcura, and the pupil the hole in the window fhutter, he was fo far mistaken as to fuppofe that it was the cryftalline hu¬ mour that correfponds to the wrall which receives the images ; nor was it difcovered till the year 1604, that this office is performed by the retina. He makes a va¬ riety of juft obfervations on vifion j and explains feveral cafes in which we imagine things to be without the eye, when the appearances are occafioned by fome affeftion of the organ itfelf, or fome motion within it. He re¬ marks alfo, that, in certain circumftances, vifion will be affifted by convex or concave glafles j and he feems al fo to have made fome fmall advances towards the dif- covery of telefcopes. He obferves, that a round and flat furface plunged into water, will appear hollow as well as magnified to an eye above it; and he explains by a figure the manner in which this effedt is pro¬ duced, The great problem concerning the meafure of re- fraftions was ftill unfolved. Alhazen and Vitellio, in¬ deed, had attempted it •, but failed, by trying to meafure the angle inftead of its fine. At laif it was difcovered by Snellius, profeffor of mathematics at Leyden. This philofopher, however, did not perfedfly underftand his own difcovery, nor did he live to publiffi any account of it. It was afterwards explained by Profeffor Hor- tenfius before it appeared in the writings of Defcartes, who publiffied it under a different form, without mak¬ ing any acknowledgement of his obligations to Snellius, whole papers Huygens affures us, were feen by Def¬ cartes. Before this time Kepler had publifhed a New Table of Angl es of Refraction, determined by his own experiments, for every degree of incidence. Kircher had done the fame, and 'attempted a theory of refrac¬ tion, on principles, which, if conduced with precifion, would have led him to the law difcovered by Snel¬ lius. Defcartes undertook to explain the caufe of refraCtion by the refolution of forces. Hence he was obliged to fuppofe that light paffes with more eafe through a denfe medium, than through a rare one. The truth of this explanation was firft queltioned by M. Fermat, w7ho af- ferted, contrary to the opinion of Defcartes, that light fuffers more refiftance in water than air, and more in glafs than in water •, and maintained, that the refiftance of different media with refpeCt to light is in proportion to their denfities. M. Leibnitz adopted the fame gene¬ ral idea, upon the principle that nature accomplifties her ends by the fhorteft methods, and that light therefore ought to pafs from one point to another, either by the fhorteft road, or that in which the leaft time is re¬ quired. At a meeting of the Royal Society, Aug. 31. 1664, it was found, with a new initrument prepared for that I C S. I73 purpofe, that the angle of incidence being 40 degrees, Hiftory. that of refraCtion is 30. About this time alfo we find v—J the firft; mention of media not refraCting the light in an Djfcoyeries exaCt proportion to their denfities. For Mr Boyle, in concerning a letter to Mr Oldenburgh, dated Nov. 3. 1664, ob-the refrac- ferves, that in fpirit of wine, the proportion of the finestion of dif- of the angles of incidence to the fines of the angles of refraftion was nearly the fame as 4 to 3 *, and that, asUance ’ fpirit of wine occafions a greater refraftion than common water, fo oil of turpentine, which is lighter than fpirit of wine, produces not only a greater refraClion than common water, but a much greater than fait water. And at a meeting held November 9. the fame year, Dr Hooke mentioned, that pure and clear falad oil produ¬ ced a much greater refraCtion than any liquor which he had tried ; the angle of refraction that anfwered to an angle of incidence of 30° being no lefs than 40° 30', and the angle of refraCtion that anfwered to an angle of incidence of 20° being 290 47'.—M. de la Hire alfo made feveral experiments to alcertain the refraCtive power of oil, and found the fine of the angle of inci¬ dence to that of refraCtion as 60 to 42; which, he ob¬ ferves, is a little nearer to that of glafs than to that of water, though oil is much lighter than water, and glafs much heavier. The members of the Royal Society finding that the refraCtion of fait water exceeded that of freffi, purfued the experiment farther with aqueous folutions of vitriol, faltpetre, and alum. They found the refraCtion of the folulion of vitriol and faltpetre a little more, but that of alum a little lefs, than common w’ater. Dr Hooke made an experiment before the Royal So¬ ciety, Feb. 11. 1663, which clearly proves that ice re- fraCts.the light lefs than water. M. de la Hire alfo took a good deal of pains to determine whether the re¬ fraCtive power of ice and water were the fame ; and he found, as Dr Hooke had done before, that ice refraCts lefs than water. By a moft accurate experiment made in 1698, in which a ray of light was tranfmitted through a Torri¬ cellian vacuum, Mr Lowthorp found, that the refrac- / tive power of air is to that of water as 36 to 34.400. He obferves, that the refraCtive power of bodies is not proportioned to the denfity, at leaft not to the fpecific gravity, of the refraCting medium. For the refraCtive power of glafs to that of water is as 55 to 34, whereas its fpecific gravity is as 87 to 34 ; that is, the fquares of their refraCtive powers are very nearly as their re- fpeCtive gravities. And there are fome fluids, which, though they are lighter than water, yet have a greater power of refraCtion. Thus the refraCtive power of fpi¬ rit of wine, according to Dr Hooke’s experiment, is to'- that of water as 36 to 33, and its gravity reciprocally as 33 to 36, or 36^. But the refraCtive powers of air and water feem to obferve the Ample direCt proportion of their gravities. The Royal Academy of Sciences at Paris endeavour¬ ed to repeat this experiment in 1700 ; but they did not fucceed.—For, as they faid, beams of light paffed through the vacuum without fuffering any refraCtion. The Royal Society being informed of this, ordered Mr Hawkflbee to make an inftrument fo]t the purpofe, under the direction of Dr Halley, for the purpofe of repeating the experiment. It confifted of a ftrong brafs prifm, two fides of which had fockets to receive two plane glaffes,. 174- . OPT Hiitory. glafles, whereby the air in the prifm might either be ‘ exhaufted or condenfed. I he prifm had alfo a mercu¬ rial gage fixed to it, to difcover the deniity of the con¬ tained air ‘y and turned upon its axis, in order to make the retractions equal on each fide when it was fixed to the end of a telefcope. The refraCting angle was near 64° '■> and the length of the telefcope, having a fine hair in its focus, was about 10 feet. The event of this ac¬ curate experiment was as follows :—Having chofen a proper objeft, vvhofe diftance was 2588 feet, June 15. O. S. 1708, in the morning, the barometer being then at 29.74, and the thermometer at 60, they firft ex¬ haufted the prifm, and then applying it to the telefcope, the horizontal hair in the focus covered a mark on the objeCf diftinClly feen through the vacuum, the two glaffes being equally inclined to the vifual ray. Then admitting the air into the prifm, the objeft was feen to rife above the hair gradually as the air entered, and when the prifm Avas full, the hair Avas obferved to hide a mark 10^ inches beloAv the former mark. After this they applied the condenfing engine to the prifm ; and having forced in another atmofphere, fo that the denfity of the included air Avas double to that of the outAvard, they again placed it before the telefcope, and, letting out the air, the objeft, Avhich before feem- ed to rife, appeared gradually to defcend, and the hair at length refted on an objeCt higher than before by the fame interval of ioI: inches. They then forced in another atmofphere ; and upon difcharging the conden¬ fed air, the objedl was feen near 21 inches loAver than before. Noav the radius in this cafe being 2588 feet, I0-| ■ inches Avill fubtend an angle of i' 8", and the angle of incidence of the vifual ray being 32 degrees (becaufe the angle of the glafs planes Avas 64°), it folloAvs from the knoAvn laAvs of refraftion, that as the fine of 390 is to that of 310 59' 26", differing from 3 2° by 34" the half of i' 8"; fo is the fine of any other angle of incidence, to the fine of its angle of refl ation ; and fo is radius, or 1000000, to 999736 ; which, therefore, is the propor¬ tion between the fine of incidence in vacuo and the fine I4 ©f refra&ion from thence into common air. Refra&ive It appears, by thefe experiments, that the refra&ive power of power of the air is proportional to its denfity. And ttmiiiwcf" *'mcc t'ie denfity of the atmofphere is as its weight dired- ly, and its temperature inverfely, the ratio of its denfi¬ ty, at any given time, may be had by comparing the heights of the barometer and thermometer ; and thence he concludes that this Will alfo be the ratio of the refrac¬ tion of the air. But Dr Smith obferves, that before avc can depend upon the accuracy of this conclufion, we ought to examine whether heat and cold alone may not alter the refradive poAver of air, Avhile its denfity con¬ tinues the fame. The French academicians, being informed of the re- fult of the above-mentioned experiment, employed M. De I’llle the younger to repeat the former experiment Avith more care : He prefently found, that the opera- ’ tors had never made any vacuum at all, there being . chinks in their inftrument, through Avhich the air had infmuated itfelf. He therefore annexed a gage to his inftrument, by which means he Avas fure of his vacuum 5 and then the refult of the experiment Avas the fame Avith that of the Royal Society. Ihe refradion Avas aRvavs i e s. proportional to the denfity of the air, excepting when Hiftory. the mercury was very low, and confequentiy the ah ""V11 ‘'J very rare j in which cafe the Avhole quantity being very fmall, he could not perceive much difftrenee in them. Comparing, however, the refradive power of the at- mofphere, obferved at Paris, with the refult of his experiment, he found, that the celt vacuum he could make Avas far ihort oi that of the regions above the at¬ mofphere. Dr Hooke firft fuggefted the idea of making allow¬ ance for the effed of the refradion of light, in palling from the tarer to the denier regions of the atinofphere, in the computed height of mountains. To this he aferibes the different, opinions of authors concerning the height of leveral very high hills. He could not ac¬ count for the appearance of very high mountains, at fo great a diftance as that at Avhich they are adually feen, but upon the fuppofition of the curvature of the vifual ray, that is made by its pafting obliquely through a me¬ dium of fuch different denhty, from the top of them to the eye, very far diftant in the horizon. All calcula¬ tions of the height of mountains that are made upon the fuppofition that the rays of light come from the tops of them, to our eyes, in ftraight lines, he confiders very erroneous. Dr Hooke aferibes the tAvinkling of the ftars to tha irregular and unequal refradion of the rays of light, which is alfo the reafon Avhy the limbs of the fun, moon, and planets, appear to wave or dance. That there is fuch an unequal diftribution of the atmofphere, he fays, Avill be evident by looking upon diftant objeds, over a piece of hot glafs, Avhich cannot be fuppofed to throAV out any kind of exhalation from itfelf, as avcII as through afeending fteams of Avater. About this time Grimaldi firft obferved that the co- Colours loured image of the fun refraded through a prifm is al-difco\ erefl ways oblong, and that colours proceed from refradion. to ariie —The way in which he firft difeovered this Avas by Vi- |r0^-re" tellio’s experiment already mentioned, in which a piece c of white paper placed at the bottom of a glafs vefiel filled Avith water, and expofed to the light of the fun, appears coloured. However, he obferved, that in cafe the two furfaces of the refraded medium Avere exadly parallel to each other, no colours Avere produced. But of the true caufe of thofe colours, he had not the leaft T(j fufpicion. This difeovery Avas referved for Sir Ifaac New- Different ton. Flaving procured a triangular glafs prifm to fa-refrangibi- tisfy himfelf concerning the phenomena of colours j he the was furprifed at the oblong figure of the coloured fpec- 'igiltOciifc0. trum, and the great difproportion betwixt its length and vered by breadth \ the former being about five times the meafure sir II;U!C of the latter. After various conjedures refpeding the^ewtcn’ caufcs of thefe appearances, he fufpeded that the colours l06°' might arife from the light being dilated by fome un- evennefs in the glafs, or fome other accidental irregula¬ rity ; and to try this, he took another prifm like the for¬ mer, and placed in fuch a manner, that the light, paf- fing through them both, might be refraded in oppofite diredions, ahd thus be returned by the latter into the fame courfe from Avhlch it had been diverted by the for¬ mer. In this manner he thought that the regular ef- feds of the firft nrifm Avould be augmented by the mul¬ tiplicity of refradions. The event was, that the light, diffufed bv the firft prifm into an oblong form, was by *7 Mr Dol- land’s dif- covery of the method of eorredl- ing the errors of re- fradling te- lefcopes. Hiftorj'. by the fecond reduced into a circular one, with as much —regularity as if it had not paffed through either of them. He then hit upon what he calls the experwientum cru- ci f, and found that light is not fimilar, or homogeneous j but that it confilfs of rays, fome of which are more re¬ frangible than others: fo that, without any difference in their incidence on the fame medium, iome of them fhall be more refraded than others ; and therefore, that, according to their particular degrees of refrangibility, they will be tranfmitted through the prifm to different parts of the oppofite wall. Since it appears from thefe experiments that differ¬ ent rays of light have different degrees of refrangibili- tf 7 it follows, that the rules laid down by preceding philofophers concerning the refradive power of water, glals, &c. mult be limited to the mean rays of the fpec- trum. Sir Ifaac, however, proves, both geometrically and by experiment, that the fine of the incidence of every kind of light, confidered apart, is to its fine of refradion in a given ratio. 1 he molt important difcovery concerning refradion fince the time of Sir Ifaac Newton is that of Mr Dol- lond, who found out a method of remedying the defeds of refrading telefcopes arifing from the different re¬ frangibility of light. Sir Ifaac Newton imagined that the different rays were refraded in the fame proportion by every medium, fo that the refrangibility of the ex¬ treme rays might be determined if that of the mean ones were given. From this it followed, as Mr Dollond obferves, that equal and contrary refradion5 muft not only deffroy each other, but that the divergency of the colours from one refradion would likewife be correded by the other, and that there could be no poffibility of producing any fuch thing as refradion without colour. Hence it was natural to infer, that all objed glaffes of telefcopes muft be equally affeded by the different ry- frarigibility of light, in proportion to their apertures, of whatever materials they may be formed. for this reafon, philofophers defpaired of bringing re- frading telefcopes to perfedion. They therefore ap¬ plied them {elves chiefly to the improvement of the re- fledmg telefcope ; dll 1747, when M. Euler, improv- mg upon a hint of Sir Ifaae Newtond, propofed to make objed glaffes of water and glafs; hoping, that by their dirterence of refradive powers, the refradions would ba¬ lance one another, and thereby prevent the difperfion of the rays that is occafioned by their difference of refran ■ gibility. This memoir of M. Euler excited the atten¬ tion of Mr Dollond. He went over all M. Euler’s cai culations, fubttituting for his hypothetical laws of re¬ fradion thofe which had been afeertained by Newton • and found, that, it followed from Euler’s own princip]es, that there could be no union of the foci of all kinds of colours, but in a lens infinitely large. Euler did not mean to controvert the experiments of Ne wton : but afl'erted, that, if they were admitted in all their extent, it would be impoffible to corred the diffe¬ rence of refrangibility occafioned by the tranfmiflion of the rays from one medium into another of different den- hty •, a corredion which he thought was very uoflible finee he fuppofed it to be effeded in the eye, which he comidered as an achromatic inftrument. To this reafoniim Mr Dollond made no reply, but by appealing to theex& penments of Newton, and the circumfpedion with which it was known that he comluded all his inquiries. OPTICS. This paper of Euler’s was particularly noticed by M. Klingenftierna of Sweden, who found that, from New¬ ton s own piinciptes, the refult of his 8th experiment could not anfwer his defcription of it. Newton found, that when light paffes out of air through feveral media, and thence goes out again into air, whether the refrad¬ ing fuifaces be parallel or inclined to one another, this light, as often as by contrary refradions it is fo corred¬ ed as to emerge inclines parallel to thofe in which it was incident, continues ever after to be white; but if the emergent rays be inclined to the incident, the white- nefs of the emerging light will; by degrees, become tinged at its edges with colours. This he tried by re¬ frading light with prilins of glafs, placed within a prifmatic veffel of water. By theorms deduced from tins experiment he infers, that the refradions of the rays of every fort, made out of any medium into air, are known by havinc the re¬ fradion of the rays of amj one fort; and alfo that the refiadion out of one medium into another is found as often as we have the refradions out of them both into any third medium. On the contrary, the Swedifh philofopher obferves, that, in this experiment, the rays of light, after paffing tin ough the water and the glafs, though they come out parallel to the incident rays, will be coloured ; but; that the fmaller the glafs prifm is, the nearer will the refult of it approach to Newton’s defcription. i his paper of M. Klingenftierna being communica¬ ted to Dollond, made him entertain doubts concerning Newton’s report, and induced him to have recourfe to experiment. He therefore cemented together two plates of glafs at their edges, fo as to form a prifmatic veffel, when flopped at the ends ; and the edge being turned down¬ wards, he placed in it a glafs prifm, with one of its edges upwards, and filled up the vacancy with clear wa¬ ter ; fo that the icfraftion of the prifm was contrary to that of the water, in order that a ray of light, tranfmit¬ ted through both thefe refrafting media, might be af- fefted by the difference only between the two refrac¬ tions. As he found the water to refraO more or lefs than the glafs prifm, he diminifhed or increafed the an¬ gle between the glafs plates, till he found t lie two con¬ trary refradlions to be equal; which he difeovered bv viewing an objea through this double prifm. For when it appeared neither raifed or depreffed, he was fatisfied that the refraftions Were equal, and that the emergent and incident rays were parallel. But according to the prevailing opinion, the objea fhould have appeared of its natural colour; for if the difference of refrangibility had been equal in the two equal refraaions, they would have reaified each other. This experiment^ therefore, fully proved the fallacy of the received opinion, by fhowing the divergency of the light by the glafs prifm to be almoft double of'that by the water ; for the image of the objea was as much in- feaed with the prifmatic colours, as if it had been feen through a glafs wedge only, whofe refraaing angle was near 30 degrees. Mr Dollond was convinced that if the refraaing an¬ gle of the water veffel could . have admitted of a fuffi- cient increafe, the divergency of the coloured rays would have been greatly diminifhed, or entirely reaificd ; and that there would hav^bcen a very great refraction with¬ out 1/76 OPT Hiftoiy. out colour j but tbe inconvenience of fo large an an- ^ vr—' gie as that 0£ the prifmatic veffel muft have been, to bring the light to an equal divergency with that of the glali, prifm whofe angle was about 60 degrees, made, it neceflary to try fome experiments of the iamekind with fmaller angles. He, therefore, got a wedge of plate glafs, the angle of which was only nine degrees ; and uling it in the fame circumftances, he increafed the angle of the water wedge, in which it was placed, till the divergency ot the light by the water was equal to that by the glafs ; that is, till the image of the object, though confiderably re- frufted by the excefs of the refraction of the water, ap¬ peared quite free from any colours proceeding from the different refrangibility of the light j and as near as he could then mealure, the refraCfion by the water was about ^ of that by the glafs. As thefe experiments proved, that different fubftances caufed the light to diverge very differently in proportion to their general refraCtive power, Mr Dollond began to fufpeCf that fuch a variety might poflibly be found in different kinds of glafs. His next objeCf, therefore, w^as to grind wedges of different kinds of glafs, and apply them together j fo that the refradfions might be made in contrary direc¬ tions, in order to difcover whether the refraCHon and the divergency of the colours would vanifh together. From thefe experiments, which were not made till 1757, he difcovered a difference far beyond his hopes in the refraCfive qualities of different kinds of glafs, with refpeft to the divergency of colours. The yellow or ffraw coloured kind, commonly called Venice gtafs, and the Englifh crown glafs, proved to be nearly alike in that refpeft; though, in general, the crown glafs feemed to make light diverge lefs than the other. 1 he com¬ mon Englilh plate glafs made the light diverge more ; and the white cryftal, or Engliffi flint glafs, moll of aU. _ He then examined the particular qualities of every kind of glafs that he could obtain, to fix upon two kinds in which the difference of their difperfive powers (hould be the greateft •, and he foon found thefe to be the crown glafs and the white flint glafs. He therefore ground one wedge of white flint, of about 25 degrees j and another of crown glafs, of about 29 degrees j which refrafted very nearly alike, but their power of making the colours diverge was very different. He then ground feveral others of crown glafs to different angles, till he got one which was equal, with refpeH to the divergency of the light, to that in the white flint glafs 5 for when they were put together fo as to refraft in contrary diredlions. the refrafred light was entirely free from colours. Then meafuring the refraflion of each wedge with thefe different angles, he found that of the white glafs to be to that of the crown glafs nearly as two to three : fo that any two wedges made in this proportion, and applied together, that they might refraft in a contrary diredlion, would tranfmit the light without any difperfion of the rays. He found alfo, that the fine of incidence in crown glafs is to that of its general refrac¬ tion as 1 to 1.53, and in flint glafs as 1 to 1.583. In order to apply thefe difcoveries to the conftru&ion of telefcopes, Mr Dollond confidered, that, in order to make two fpherical glaffes that Ihould refract the light ICS* in contrary directions, tne one muff be concave and tbe Hlftory, other convex; and as the rays are to converge to a real focus, the excefs of reffadlion mull be in the convex lens. Alfo, as the convex glafs is to refraft the moll, it appeared from his experiments, that it mull be made of crown glafs, and the concave of white flint glafs. Farther, As the refradlions of Ipherical glaffes are in the inverfe ratio of their focal diffances, it Inflows, that the focal diltances of the two glaffes Ihall be inverfely as the ratios of the refractions of the wedges; for being thus proportioned, every ray of light that paffes through this combined glafs, at whatever diftanee it may pafs from its axis, will conffantly be refra&ed, by the dif¬ ference between two contrary reflations, in the propor¬ tion required j and therefore the different refrangibility of the light will be entirely removed. The difficulties which occurred in the application of this reafoning to pratice, arofe from the following cir¬ cumftances. In the firll place, The focal diftances, as well as the particular furfaces, muft be very nicely pro¬ portioned to the denfities or refra&ing powers of the glaffes, which are very apt to vary in the fame fort of glafs made at different times. Secondly, '1 he centres of the two glaffes muft be placed truly in the common axis of the tekfeope, otherwife the defired tffedf will be in a great meafure deftroyed. And, thirdly, 1 he difficulty of forming the four furfaces of the lenfes ex- aflly fpherical. At length, however, after numerous trials, he was able to conftruft refradling telefcopes, with fuch apertures and magnifying powers, under li¬ mited lengths, as far exceeded any thing that had been produced before, reprefenting objects with great di- ftindtnefs, and in their natural colours. As Mr Dollond did not explain the method by which he determined the curvatures of his lenfes, the celebrated M. Clairaut, who had begun to inveftigate this fubjeft, endeavoured to reduce it to a complete theory, from which rules might be deduced, for the benefit of the pra&ical optician. With this view, therefore, he endeavoured to afeer- tain the refraflive power of different kinds of glafs, and alfo their property of difperfing the rays of light. For this purpofe he made ufe of two prifms, as Mr Dollond had done : but, inftead of looking through them, he placed them in a dark room 5 and when the tranfmitted image of the fun was perfedlly white, he concluded that the different refrangibility of the rays was corrected. In order to afeertain more eafily the true angles that prifms ought to have in order to deftroy the effedl of the difference of refrangibility, he conftrufted a prifm which had one of its furfaces cylindrical, with feveral degrees of amplitude. By this means, without changing his prifms, he had the choice of an an infinity of angles} among which, by examining the point of the curve furface, which, receiving the folar ray, gave a white image, he could eafily find the true one. He alfo afeer- tained the proportion in which different kinds of glafs feparated the rays of light, by meafuring, with proper precautions, the oblong image of the fun made by tranf- mitting through them a beam of light. In thefe experiments M. Clairaut was aflifted by M, de Tournieres, and the refults agreed with Mr Dol¬ lond’s in general} but whereas Mr Dollond had made the difperfion of the rays in glafs and in water to be as . five OPT Hiftory. five to four (acknowledging, however, that he did not ' pretend to do it with exadtnefs), thefe gentlemen, who took more pains, found it to be as three to two. For the theorems and problems deduced by M. Clairaut from thefe new principles of optics, with a view to the per¬ fection of telefcopes, we muft refer the reader to Mem. Acad. Par. 1756, 1757. The fubjeCt of achromatic telefcopes wras alfo invefli- gated by the illuitrious D’Alembert. This excellent mathematician propofed a variety of new conftruCtions, the advantages and difadvantages of which he diltinCtly notes j at the fame time that he points out feveral methods of correcting the errors to which thefe telefcopes are liable : as by placing the object glaffes, in fome cafes, at a fmall diitance from one another, and fome- times by ufing eye glaffes of dift'erent refraCtive powers ; which is an expedient that does not feem to have occur¬ red to any perfon before him. He even (hows, that telefcopes may be made to advantage, confiding of only one objcCt glafs, and an eye glafs of a different refraCtive power. Some of his condruCtions have two or more eye glaffes of different kinds of glafs. This fubjeCt be confidered at large in one of the volumes of his Opufcu/es Mnthematigues. We have alfo three memoirs of M. D’Alembert upon this fubjeCt, among thofe of the French Academy in the years 1764, 1765, and 1767. The invedigations of Clairaut and D’Alembert do not feem to have adided the exertions of foreign artids. The lelefcopes made in England, according to no exaft rule, as foreigners fuppofed, were greatly fuperior to any that could be made elfewhere, though under the immediate direction of thofe able calculators. M. Euler who fird gave occadon to this inquiry, having perfuaded himfelf, both by reafoning and calcula¬ tion, that Mr Dollond had difeovered no new principle in optics, and yet not being able to controvert Mr Short’s teilimony in favour of the achromatic telefcopes, concluded that this extraordinary effeCt was partlv ■owing to the crown glafs not tranfmitting all the red light, which would have otherwife come to a different focus, and have didorted the image ; but principally to bis giving a juft curvature to his glafs, which he dH not doubt would have produced the fame effeCt if the lenfes had all been made of the fame kind of glafs. At another time he imagined that the goodnefs of Mr Dollond’s telefcopes might be owing to the eye glafs. If my theory, fays he, be true, this difagreeable confequence follows, that Mr .Dollond’s objeft glaffes cannot be exempt from the difperfion of colours : yet a regard to ■To refpeCtable a teftimony embarraffes me extremely, it being as difficult to queftion fuch exprefs authority,’ as to abandon a theory which appears to me well founded, and to embrace an opinion which is as contrary to all the eftabliftied laws of nature as it is'ftrange and feem- ingly abfurd. He even appeals to experiments made in a darkened room •, in which he fays, lie is confident that Mr Dollond’s objeft-glaffes would appear to have the fame defefls to which others are fubjeft. Not doubting, however, but that Mr Dollond had made fome improvement in the conftru&ion of tele¬ fcopes, by the combination of glaffes, he abandoned his former projeft, in which he had recourfe to different media, and confined his attention to the correftion of the errors which arife from the curvature of lenfes. But friule l)e was proceeding, as he imagined, upon the true Vol. XV. Part I. I c s. principles of optics, he could not help expreffing his furprife that Mr Dollond ffiould have been led to fo important a difeovery by reafoning in a manner quite contrary to the nature of things. At length, however, M. Euler was convinced of the reality and importance of Mr Dollond’s difeoveries ; and frankly acknowledges, that perhaps he ffiould never have been brought to afient to it, had he not been affured by his friend M. Clairaut that the experiments of the Engliffi optician might be depended upon. The experiments of M. Zeiber, how- ever, gave him the moft complete fatisfaclion with re- fpect to this fubject. This gentleman demonftrated, that it is the lead in the compofition of glals which produces the variation in its difperfive power ; and, by increafing the quantity of lead in the mixture, he produced a kind of glafs, which occafioned a much greater feparation of the extreme rays than the flint glals which Mr Dollond had made ufe of. From thefe new principles M. Euler deduces theo¬ rems concerning the combination of the lenfes, and, in.a manner fimilar to M. Clairaut and D’Alembert’ points out methods of conftrutfing achromatic tele¬ fcopes. While he was employed upon this fubjeft, he informs us, that he received a letter from M. Zeiher, dated Peterfburgh, 30th of January 1764, in which he gives him a particular account of the fuccefs of his experi¬ ments on the compofition of glafs; and that, having mixed minium and fand in different proportions, the re- fult of the mean refraaion and the difperfion of the rays varied according to the following table. 18 Different compoli- tions of glafs for the purpofe of correcting- the imper- fedtion of telefcopes. Proportion of minium to flint. I. II. III. IV. V. VI. Ratio of the mean refraaion from air into glafs. Difperlion of the rays in comparifon of crown glafs. 2028 I^3° t7&7 1732 1724 1664 1000 1000 1000 I coo xcoo IOOO 4800 3550 3259 2207 1800 I354 1000 1000 1000 1000 1000 1000 From this taole it is evident, that a greater quantity of lead not only produces a greater difperfion of the rays, but alfo increafts the mean refraaion. The firft of thefe. kinds of .glafs, which contains three times as much minium as flint, will appear very extraordinary • fince, hitherto, no tranfparent fubftance has been known " hole refraaive power exceeded the ratio of two to one’ and fince the difperfion occafioned by this glafs is almoft five times as great as that of crown glafs, which could fcarcely.be believed by thofe who entertained any doubt concerning the fame property in flint glals, the effea of which is three times as great as crown glafs. Here, however, M. Euler announces to us another difeovery of M. Zeiher, no lefs furprifing than the for- me.r, and which difconcerted all his fchemesfor recon¬ ciling the above-mentioned phenomena. As the fix kinds of glafs mentioned in the preceding table were com- poled of nothing but.minium and flint, M. Zeiher hap¬ pened to think of mixing alkaline falts with them in order to give the. glafs a confiftence more proper fur- diontnc ufes: This mixture, however, greatly diminilh- Z * 178 Hiftory. 19 Difcovery of Dr Ro¬ bert Blair for this purpofe. OPT ed the mean refraftion, almoft without making any change in the difperfion. After many trials, he is laid to have obtained a kind of glafs, which occafioned three times as great a difperfion of the rays as the common glafs, at the fame time that the mean refraclion rvas only as 1.61 to 1. } though we have not heard that this kind of glafs was ever ufed in the conitrufrion of telefcopes. Mr Dollond was not the only optician who had the merit of difcovering the achromatic telefcope, as this inftrument appears to have been conftru&ed by a private gentleman—Mr Chefter More Hall. He obferved that prifms of flint glafs gave larger fpecfra than prifms of water, when the mean refra&ion was the fame in both. He tried prifms of other glafs, and found fimilar differ¬ ences j, and he applied this difcovery to the fame pur- pofes as Mr Dollond. Thefe fa«5ts came out in a procefs raifed at the inftance of Watkins optician, as alfo in a publication of Mr Ramfden. There is, however, no evidence that Dollond ftole the idea from Mr Hall, or that they had not both claims to the difcovery. The bell refrafting telefcopes, conftrudled on the principles of Mr Dollond, are flill defeftive, on account of that colour which, by the aberration of the rays, they give to objects viewed through them, unlels the objedt glafs be of fmall diameter. This defedl philofo- phers have endeavoured to remove by various contrivan¬ ces, and Bofcovich has, in his attempts for this purpofe, difplayed much ingenuity •, but the philofopher w hole exertions have been crowned with moll fuccefs, and who has perhaps made the molt important difcovery in this fcience, is Dr Robert Blair profeflbr of pradlical af- tronomy in the college of Edinburgh. By a judicious fet of experiments, he has proved, that the quality of difper- fing the rays in a greater degree than crown glafs, is not confined to a few media, but is poffeffed by a great variety of fluids, and by fome of thefe in a moll extraordinary de¬ gree. He has Ihown, that though the greater refrangibili- ty of the violet rays than of the red rays, when light paffes from any medium whatever into a vacuum, may be con- fidered as a law of nature •, yet in the paflage of light from one medium into another, it depends entirely on the qualities of the media which of thefe rays lhall be the moll refrangible, or whether there lhall be any differeirce in their refrangibility. In order to corredt the aberration arifing from difference of refrangibility among the rays of light, he inllituted a fet of experi¬ ments, by which be detedled a very lingular and im¬ portant quality in the muriatic- acid. In all the dif- perfive media hitherto examined, the green rays, which are the mean refrangible in crown glafs, were found among the lefs refrangible ; but in the muriatic acid, thefe fame rays were found to make a part of the more refrangible. This difcovery led to complete fuccefs in removing the great defedt of optical inltruments, viz. that diflipation or aberration of the rays which arifes from their unequal refrangibility, and has hitherto rendered it impoflible to converge all of them to one point either by fingle or oppofite refradtions. A fluid, in which the particles of marine acid and metalline par¬ ticles hold a due proportion, at the fame time that it feparates the extreme rays of the fpedtrum much more than crown glafs, refradts all the orders of the rays in the fame proportion that glafs does : and hence rays of all colours made to diverge by the refradtion of the ICS. glafs, may either be rendered parallel by a fubfequent Hiitory. refradtion in the confine of the glafs and .this fluid j or, * by weakening the refradtive denfity of the fluid, the refradtion which takes place in the confine of it and glafs may be rendered as regular as refledtion, without the lead colour whatever. The dodtor has a telefcope, not exceeding 15 inches in length, with a compound objedt glafs of this kind, which equals in all refpedts, if it does not furpafs, the belt ©f Dollond’s 42 inches long. See Phil. Tranf. Edin. vol. iii. _ 20 We fhall conclude the hiitory of the difeoveries con- Of the re- cerning refradtion, with fome account of the refradtion of the atmofphere.—Tables of refradtion have been cal- eulated by Mr Lambert, with a view to corredt inac¬ curacies in determining the altitudes of mountains geo¬ metrically. The obfervations of Mr Lambert go upon the fuppofition that the refradtive power of the atmo¬ fphere is invariable : But as this is by no means the cafe, his rules inult be confidered as true only for the mean ftate of the air. VW XT,.fnkfprvpd ts s o t- L' O r's 1"tro Y*1 f refradtive power of the atmofphere, which demonltratcs how little we can depend upon the calculated heights of mountains, ■when the obfervations are made with an in¬ ftrument, and when the refradtive power of the air is to be taken into the account. Being defirous to learn, by obfervation, how far the mercury would defeend in the barometer at any given elevation, be propofed to meafure the height of fome of their higheft hills j but when he attempted it, he found his obfervation fo much di- fturbed by refradtion, that he could obtain no certain refult. Having meafured one hill of a confiderable height, in a clear day, and obferved the mercury at the bottom and at the top, he” found, that about 19 feet or more were required to make the mercury fall x-^th of an inch ; but afterwards, repeating the experiment, when the air was rather grofs and hazy, he found the fmall angles fo much increafed by refradtion as to make the hill much higher than before. He afterwards fre¬ quently made obfervations at his own houfe, by point¬ ing a quadrant to the tops of fome neighbouring hills, and obferved that they would appear higher in the morning before funrife, and alfo late in the evening, than at noon in a clear day, by feveral minutes. In one cafe the elevations of the fame hill differed more than 30 minutes. M. Euler confidered the refradtive power of the atmofphere, as affedted by different degrees of heat and elafticity ; in which he (hows, that'its refradtive power, to a confiderable diftance from the zenith, is fufficiently near the proportion of the tangent of that diftance, and that the law of refradtion follows the diredt ratio of the difference marked by the thermometer j but when ftars are in the horizon, the changes are in a ratio fomewhat greater than this, more efpecially on account of the va¬ riation in the heat. _ 21 As the denfity of the atmofphere varies with its La Place altitude, and as the irregular curvature of the earth ^ caufes a conftant change in the inclination of the drata through which any ray of light paffes to the eye, the cai refrac- refradtion cannot be obtained from the denfity of the tion. atmofphere, and the angular diredtion of the refradted ray. By comparing aftronomical with meteorological obfervations, however, the celebrated M. La Place, has given OPT ftiftory. given a complete folution of this very important pro- blem. phenomena known by the names of mirage, ot ure'fiilai' looming, and fata morgana, have been traced to irre- rcfratftions. gularities of refractions arifing from accidental changes in the temperature of the atmofphere. From the rare- fa6tion of the air near the furface of water, buildings, or the earth itfelf, a diltant object feen through this rare¬ fied air fometimes appears deprefl'ed inftead of raifed by refraction ) at other times it appears both elevated and depreffed, f« that the object feems double, and fome¬ times triple, one of the images being in an inverted pofition. This fubjeft is much indebted to the refear- ches of the ingenious Dr Wollaflon, who has imitated thefe natural phenomena by viewing obje&s through the rarefied air contiguous to a red-hot poker, or through a faline or faccharine folution with water and fpirit of wine floating upon its furface. This branch of optics has alfo been well illullrated by Mr Vince and Mr Hud- dart. Sect. II. Difcoveries concerning the Reflet! ion of Light. Difcoveries The followers of Plato were acquainted with the « the an- equality between the angles of incidence and reflexion ; dents. antj jt probable that they difcovered this, by obferving a ray of the fun reflected from Handing water, or fome other polilhed body $ or from attending to the images of objects reflected by fuch furfaces. If philofopbers paid any attention to this phenomenon, they could not but perceive, that, if the ray fell nearly perpendicular upon fuch a furface, it was reflefted near the perpendicular •, and if it fe” obliquely, it was reflected obliquely : and obfervations upon thefe angles, the molt rude and imper¬ fect, could not fail to convince them of their equality, and that the incident and reflected rays were in the fame plane. Ariftotle was fenfible that it is the reflection of light from the atmofphere which prevents total darknefs after the fun fets, and in places where he does not Ihine in the day-time. He was alfo of opinion, that rainbows, halos, and mock funs, were occafioned by the reflection of the funbeams in different circumltances, by which arfimper- feCt image of his body was produced, the colour only being exhibited, and not his proper figure. The image, he fays, is not Angle, as in a mirror •, for each drop of rain is too fmall to refleCt a vifible image, but the con¬ junction of all the images is vifible. Treatife of Without inquiring any farther into the nature of light optics by or vifion, the ancient geometers contented themfelves Euclid. with deducing a fyftem of optics from two faCts, the reCtilineal progrefs of light, and the equality of the angles of incidence and reflection. The treatife of optics afcribed to Euclid is employed in determining the ap¬ parent fize and figure of objeCts, from the angle which they fubtend at the eye, and the apparent place of the image of an objeCt reflected from a polifhed miror. This place he fixes at the point where the reflected ray meets a perpendicular to the mirror drawn through the objeCt. But this work is fo imperfeCt and inaccurate, that it 25 does not feem to be the production of Euclid. Burning It appears from Pliny and LaCtantius, that burning the an° gHA*65 were known to the ancients. In one of the plays cients. of Arittophanes, indeed, a perfon is introduced who pro- pofes to deltroy his adverfary’s papers by means of this I c s. inftrument 5 and there is reafon to believe that the Romans had a method of lighting their facred fire by means of a concave fpeculum. It feem indeed to have been known A. C. 433, that there is an increafeof heat in the place where the rays of light meet, after reflection from a concave mirror. The burning power of concave mirrors is noticed by the author of the work afcribed to Euclid. If we give any credit to what fome ancient hiltorians are faid to have written concerning the exploits of Archimedes, we fhall be induced to think that he conftruCted fome very powerful burning mirrors : but nothing being faid of other perfons making ufe of h« inventions, the whole account is very doubtful. It is allowed, however, that this eminent geometer did write a treatile on the fubjeCt of burning mirrors, which has not defcended to our times. B. Porta fuppofes that the burning mirrors of the ancients were parabolic and made of metal. It follows from the properties of this curve, that all the rays which fall upon it, parallel to its axis, will meet in the fame point at the focus. Confequently, if the vertex of the parabola be cut off, as in fig. 1. it will make a con¬ venient burning mirror. In fome drawings of this in- firument the fruftum is fo fmall, as to look like a ring. With an inllrument of this kind, it is thought, that the Romans lighted their facred fire, and that with a fimilar mirror Archimedes burnt the Roman fleet; ufing a lens, to throw the rays parallel, when they had been brought to a focus; or applying a fmaller parabolic mirror for this purpofe, as is reprefented fig. 2. 2- The nature of reflection was, however, very far from of feelr-r being underftood. Even Lord Bacon, who made much images in greater advances in phyfics than his predeceffors, fup- the air. pofed it poflible to fee the image reflected from a look- ing glafs, without feeing the glafs itfelf; and to this purpofe he quotes a ftory of Friar Bacon, who is re¬ ported to have apparently walked in the air between two fteeplps, and which was thought to have been ef- fefted by reflection from glaffes while he walked upon the ground. Vitellio had endeavoured to Ihow that it is noflible, by means of a cylindrical convex fpeculum, to fee the images of objeCts in the air, out of the fpeculum, when the objeCts themfelves cannot be feen. But from his defcription of the apparatus, it will be feen that the eye was to be directed towards the fpeculum placed within a room, while the objeCt and the fpeCtator were with¬ out it. But as no fuch effeCt Can be produced by a convex mirror, Vitellio muft have been under fome de¬ ception with refpeCt to his experiment. B. Porta fays, that this eff Ct may be produced by a plain mirror only; and alfo by the combination of a plain and a concave mitror. Kirchef alfo fpeaks of the poffibility of exhibiting thefe pendulous images, and fuppofes that they are re¬ flected from the denfe air: But the molt perfeCt and pleafing deception, depending upon the images in the air, is one of which this writer gives a particular ac¬ count in his Ars Magna Lucis et Umbrae, p. 783. In this cafe the image is placed at the bottom of a hollow polifhed cylinder, by which means it appears like a real folid fubftance, fufpended within the mouth of the veffel. ay It was Kepler who firft difcovered, that the apparent Difcoveries places of objeCts feen by reflecting mirrors depended u^eP^er* Z 2 upon 179 Hiftorv- Plate CCCLXXV. fig. 1. j8o OPT Hirtory. upon the angle which the rays of light, iflfuing from the extreme part of an object, make with one another after 23 refleflion. Difcoveries Mr Boyle made feme curious obfervations concern- of Mr Jng refleftisig powers of differently coloured fub- fiances. In order to fhew that fnow ihines by a bor¬ rowed and not by a native light, he placed a quantity of it in a room, from which all foreign light was ex¬ cluded, and found that it was completely invifible. To try whether white bodies refleft more light than others, he held a fheet of white paper in a funbeam admit¬ ted into a darkened room *, and obferved that it reflect¬ ed much more light than a paper of any other colour, a confiderable part of the room being enlightened by it. To fhow that u'hite bodies refleCt the rays outwards, he adds, that common burning glaffes require a long time to burn or difcolour white paper ; that the image of the fun was not fo well defined upon white paper as upon black ; that when he put ink upon the paper, the moifture would be quickly dried up, and the paper, which he could not burn before, would prefently take fire •,—and that by expofing his hand to the fun, with a thin black glove upon it, it would be fuddenly and more confiderably heated, than if he held his naked hand to the rays, or put on a glove of thin white leather. To prove that black is the reverfe of white, with refpedl to its property of reflefting the rays of the fun, he procured a large piece of black marble, ground into the form of a large concave fpeculum, and found that the image of the fun reflefted from it was far from offending or dazzling his eyes, as it would have done from another fpeculum ; and though this was large, he could not for a long time fet a piece of wood on fire with it ; though a far lefs fpeculum, of the fame form, and of a more refleCling fubilance, would prefently have made it flame. To fatisfy himfelf flill farther with refpefl to this fubjeft, he took a tile •, and having made one half of its furface white and the other black, he expofed it to the fummer fun. Having let it lie there fome time, he found, that while the whitened part remained cool, the black part wras very hot. He fometimes left part of the tile of its native red ; and, after expofing the whole to the fun, obferved that this part grew hotter than the white, but not fo hot as the black part. Of the in- remarkable property of lignum nephriticum (a fufion of fpecies of guilandina) was firft obferved by Kircher. lignum ne- Mr Boyle has deferibed this lignum nephriticum as a phriticum. kind of wood, which was brought from Mexi¬ co, and which had been thought to tinge water of a green colour only ; but he ,fays that he found it to communicate all kinds of colours. If an infufion of this wood be put into a glafs globe, and expofed to a flrong light, it will be as colourlefs as pure water \ but if it be carried into a place a little (haded, it will be a beauti¬ ful green. In a place dill more (haded, it will incline to red ; and in a very (hady place, or in an opaque veffel, it will be green again. Mr Boyle firft diftin&ly noted the two very different colours which this remarkable timffure exhibits by tranf- mitted and refledled light. If it be held dire&ly between the light and the eye, it will appear tinged (excepting the very top of it, where a fky-coloured circle fome¬ times appears) almoft of a golden colour, except the in- I c s. fufion be too llrong ; in which cafe it will be dark or Hiftory. reddilh, and requires to be diluted with water. But if v—' it be held from the light, fo that the eye be between the light and the phial, it will appear of a deep lively blue colour 5 as will alfo the drops, if any lie on the outfide of the glafs. When a little of this tinfture was poured upon a (heet of white paper, and placed in a window where the fun (hone upon it, he obferved, that if he turned his back upon the fun, the ihadow of anybody projedled upon the liquor would not be all dark, like other fhadows j but that part of it would be curioufly coloured, the edge of it next the body being almofl: of a lively golden colour, and the more remote part blue. Obferving that this tindlure, if it were too deep, was not tinged in fo beautiful a manner, and that the impregnating virtue of the wood did, by frequent in¬ fufion in frefh water, gradually decay, he conjeflured that the tin&ure contained much of the effential fait of the wood ; and to try whether the fubtle parts, on which the colour depended, were volatile enough to be diftilled, without diffolving their texture, he applied fome of it to the gentle heat of a lamp furnace j but he found all that came over was as limpid and colourlefs as rock water, while that which remained behind was of fo deep a blue, that it was only in a very ftrong light that it appeared of any colour. Having fometimes brought a round long-necked phial, filled with this tinfiure, into a darkened room, into which a beam of the fun was admitted by a fmall aperture j and holding the phial fometimes near the funbeams, and fometimes partly in them and partly out of them, changing alfo the pofition of the glafs,. and viewing it from feveral parts of the room, it exhi¬ bited a much greater variety of colours than it did in an enlightened room. Befides the ufual colours, it was- red in fome places and green in others, and within were intermediate colours produced by the different mixtures of light and (hade. It was not only in this tinfture of lignum nephriti¬ cum that Mr Boyle perceived the difference between refledled and tranfmitted light. He obferved it even in gold, though no perfon explained the caufe of thefe appearances before Sir Ifaac Newton. He took a piece of leaf gold, and holding it betwixt his eye and the light, obferved, that it did not appear of a golden colour, but of a greenifh blue. He alfo obferved the fame change of colour by candle light ; but the experiment did not fucceed with a leaf of (liver. The conftitution of the atmofphere and of the fea, we (hall find, by more recent obfervations, to be fimilar to that of this infufion ; for the blue rays, and others of a faint colour, do not penetrate fo far into them as the red, and others of a (Ironger colour. The firfl: diftindt account of the colours exhibited by Mr jg® jef5 thin plates of various fubftances is to be found among account of the obfervations of Mr Boyle. To (how that colours the colours may be made to appear or vanifh, where there is no ac-of tllin eeffion or change either of the fulphureous, the faline,lllates‘ or the mercurial principle of bodies, he obferves, that all chemical effential oils, as alfo good fpirit of wine, being (haken till they rife in bubbles, appear of various colours ; which immediately vanifh when the bubbles burft, fo that a colourlefs liquor may be immediately made to exhibit a variety cf colours, and lofe them in a- moment. OPT Hiftory. moment, without any change in its effential principles, '"—nr™”' He then mentions the colours that appear in bubbles of foap and water, and alfo in thofe of turpentine. He fometimes got glafs blown fo thin as to exhibit fimilar colours ; and obferves, that a feather, and alfo a black ribbon, held at a proper diftance, between his eye and the fun, (bowed a variety of little rainbows, with very vivid colours, none of which were conftantly to be feen t in the fame obje&s. Dr Hooke’s This fubjeft was more carefully invelligated by Dr account of Hooke, who promifed, at a meeting of the fociety on thefe co- the 7th of March 1672, to exhibit, at their next meet- lours. Jng^ fomething which had neither refledtion nor refrac¬ tion, and yet was diaphanous. Accordingly he produ¬ ced the famous coloured bubble of foap and water of which fuch ufe was afterwards made by Sir Ifaac New¬ ton, but which Dr Hooke and his contemporaries feem to have overlooked in Mr Boyle’s treatife on colours, though it was publilhed nine years before. It is no wonder that fo curious an appearance excited the at¬ tention of that inquifitive body, and that they fliould defire him to bring an account of it in writing at their next meeting. By the help of a frnall glafs pipe, there were blown feveral fmall bubbles, out of a mixture of foap and wa¬ ter. At firft, they appeared white and clear; but, after fome time, the film of water growing thinner, there ap¬ peared upon it all the colours of the rainbow : Firft, a pale yellow; then orange, red, purple, blue, green, &c. with the fame feries of colours repeated ; in which it was farther obfervable, that the firft and laft ferics were very faint, and that the middlemoft feries was very bright. After thefe colours had pafled through the changes above mentioned, the film of the bubble began to appear white again ; and prefently, in feveral parts of this fecond white film, there were feen feveral holes, which by degrees grew very large, feveral of them run¬ ning into one another. Dr Hooke was the firft who obferved the beautiful colours that appear in thin plates of Mufcovy glafs. With a microfcope he could perceive that thefe colours were ranged in rings furrounding the white fpecks or flaws in this thin fubftance, that the order of the colours was the very fame as in the rainbow, and that they were often repeated ten times. But the colours were difpofed as in the outer rainbow. Some of them alfo were much brighter than others, and fome of them very much broader. He alfo obferved, that if there was a part where the co¬ lours were very broad, and confpicuous to the naked eye, they might be made, by prefling the part with the finger, to change places, and move from one part to another. Laftly, He obferved, that if great care be ufed, this fubftance may fplit into plates of one-eighth or one-fixth of an inch in diameter, each of which will appear through a microfcope to be uniformly adorned with fome one vivid colour, and that thefe plates will be found upon examina¬ tion to be of the fame thicknefs throughout. A phenomenon fimilar to this was noticed' by Lord Brereton, who at a meeting of the Royal Society in 1666, produced fome pieces of glafs taken out of a church window, both on the north and on the fouth fide of it ; they were all eaten in by the air, but the piece taken from the fouth fide had fome colours like thofe of the rainbow upon it, which the others on the north .fide had not. It cannot be doubted, but that in 4 I C S. ,8i all thefe cafes, the glafs is divided into thin plates, Hiftory. which exhibit colours, upon the fame principle with ’ v thofe which Dr Hooke obferved in the bubble of foap and water, and in the thin plate of glafs, which we (hall find more fully explained by Sir Ifaac Newton. The enquiries of M. Bouguer concerning the reflec¬ tion of light are worthy of particular notice. They are fully detailed in his Traite (POptique, apofthumous work publilhed by La Caille in 1760. ^ In order to compare different degrees of light, he al- Difcoveries ways contrived to place the radiant bodies or otherof M- Em¬ bodies illuminated by them, in fuch a manner that hesue^• could view them diftinftly at the fame time; and he either varied the diitances of thefe bodies, or modified their light in fome other way, till he could perceive no difference between them. Then, confidering their dif¬ ferent diftances, or the other circumftances by which their light was affedted, he calculated the proportion which they would have borne to each other at the fame diftance, or in the fame circumftances. To afeertain the quantity of light loft by refleftion, plate he placed the mirror, or refledlirig lurface, B, on which ccclxxv. the experiment was to be made, truly upright; and %• 3- having taken two tablets, of precifely the fame colour, or of an equal degree of whitenefs, he placed them ex- adtly parallel to one another at L and D, and threw light upon them loy means of a lamp or candle, P, placed in a right line between them. He then placed himfelf fo, that with his eye at A he could fee the tablet E, and the image of the tablet D, refle&ed from the mirror B, at the fame time ; making them as it were, to touch one another. He then moved the candle along the line ED, fo as to throw more or lefs light upon either of them, till he could perceive no difference in the ftrength of the two lights that came to his eye. After this, he had nothing more to do than to meafure the diftances EP and DP, and then the in- tenfity of the lights was as EP* to DP*. To find how much light is loft by oblique refledfion, Fig. 4, he took two equally polilhed plates, D and E, and caufed ° them to be enlightened by the candle P. While one of them, D, was feen at A, by refledtion from B, placed in a pofition oblique to the eye, the other, E, was fo placed, as to appear contiguous to it ; and removing the plate E, till the light which it refledted was no ftronger than that which came from the image D, feen by reflec¬ tion at B, he eftimated the quantity of light that was loft by this oblique refledtion, by the fquares of the diftances of the two objedts from the candle. In order to afeertain the quantity of light loft by Fig. 5. refledtion with the greateft exadtnefs, M. Bouguer in¬ troduced two beams of light into a darkened room, as by the apertures P and Q; which he had fo contrived, that he could place them higher and lower, and enlarge or conlradt them at pleafure ; and the refledting fur- face (as that of a fluid contained in a veflel) was placed horizontally at O, from which the light com¬ ing through the hole P, was refledted to R, upon the fereen GH, where it was compared with another beam of light that fell upon S, through the hole £) ; which he made fo much lefs than P, as that the fpaces S and R were equally illuminated ; and by the proportion that the apertures P and £) bore to each other, he calcu¬ lated what quantity of light was loft by the refledlion - at O. It I 8 2 OPTICS. Hiftorv. 33 Expei i- raent of M. BulFon. It was neceflary, he obferves, that the two beams of light PO and QS (which he ufually made 7 or 8 feet long) fhould be exaftly parallel, that they might come from two points of the Iky of the fame altitude, and having precifely the fame intcnfity of light. It was alfo neceffary that the hole thould be a little higher than P, in order that the two images Ihould be at the fame height, and near one another. It is no lefs necef¬ fary, he fays, that the fcreen GH be exactly vertical, in order that the direct and refletted beams may fall upon it, with the fame inclination ; lince, otherwife, though the two lights were perfectly equal, they would not il¬ luminate the fcreen equally. This difpolhion, he fays, ferves to anfwer another important condition in thefe experiments 5 for the direct ray QS mull be of the fame length with the fum of the incident and reflected rays, PO and OR, in order that the quantity of light intro¬ duced into the room may be fenlibly proportional to the lizes of the apertures. Before we proceed to detail the other experiments of Bouguer, we fhall notice fome which were made pre¬ vious to them by BulFon on the diminution of light by refledion, and the tranfmiflion of it to conliderable di- ftances through the air. By receiving the light of the fun in a dark room, and comparing it with the fame light of the fun refleded by a mirror, he found that at fmall diftances, as four or five feet, about one half was loft by refiedion. When the diftances were 100, ^00, and 300 feet, he could hardly perceive that it loft any of its intenfity by being tranfmitted through fuch a fpace of air. He afterwards made the fame experiments with candles, in the following manner : He placed himfelf nppofite to a looking glafs, Avith a book in his hand, in a dark room-, and having one candle lighted in the next room, at the diftance of about 40 feet, he had it brought nearer to him by degrees, till he could juft diftinguilh the letters of the book, which was then 24 feet from the candle. He then received the light of the candle, refleded by the looking glafs, upon his book, carefully excluding all the light that rvas refleded from any thing elfe ; and he found that the diftance of the book from the candle, including the diftance from the book to the looking glafs (which was only half a foot) Avas in all 15 feet. He repeated the experiment feveral times, with nearly the fame refult; and therefore concluded, that the quantity of dired is to that of refleded light as 376 to 225 *, fo that the light of five candles refleded from a plain mirror is about equal to that of txvo candles. From thefe experiments it appeared, that more light Avas loft by refledion of the candles than of the fun, Avhich M. Buffon thought Avas owing to this circum- ftance, that the light iifuing from the candle diverges, and therefore falls more obliquely upon the mirror than the light of the fun, the rays of which are nearly parallel. Thefe experiments and obfervations of M. Buffon, though curious, are inferior to thofe of M. Bouguer, both in extent and accuracy. In order to afcertain the difference in the quantity of light refleded by glafs and polilhed metal, he ufed a fmooth piece of glafs one line in thicknefs, and found the reflec- that Avhen it Avas placed at an angle of 15 degrees Avith tion of glafs the incident rays, it refleded 628 parts of 1000 which •edmeuf1" ^ uFon ^ \ at t^ie ^ame t™e t'iat a metallic mirror, which he tried in the fame circumftances, refleded only 5 34 Mr Bou- guer’s dif- coveries •concerning 961 of them. At a lefs angle of incidence much more Hiftory. light Avas refleded : fo that at an angle of three degrees the glafs refleded 700 parts, and the metal fomething lefs, as in the former cafe. In the cafe of unpolilhed bodies, be found that a piece of Avhite plafter, placed at an angle of 750, with the incident rays, refleded Part of the light that is re¬ ceived from a candle nine inches from it. White paper, in the fame circuinftanees, refleded in the fame propor¬ tion ; but at the diftance of three inches, they both re¬ fleded 150 parts out of 1000. Proceeding to make farther obfervations on the fub- jed of refleded light, he premifes the two folloAving theorems, Avhich he demonftratesgeometrically. j.When the luminous body is at an infinite diftance, and its light is received by a globe, the furface of Avhich has a per- fed polilh, and abforbs no light, it refleds the light equally in all diredions, provided it be received at a confiderable diftance. He excepts the place Avhere the ftiadoAv of the globe falls: becaufe this is no more than a Angle point, with refped to the immenfity of the fpherical furface Avhich receives the light. 2. The quantity of light refleded in one certain di- redion Avill ahvays be exadly the fame, Avhether it be refleded by a very great number of fmall polithed he- mifpheres, by a lefs number of large hemifpheres, or by a Angle hemifphere, provided they occupy the fame bafe, or cover the fame ground plan. The ufe he propofes to make of thefe theorems is to afiift him in diftinguifhing Avhether the light refleded from bodies be owing to the extindion of it Avithin them, or Avhether the eminences Avhich coyer them haAre not the fame effed as the ftnall polifhed hemifpheres above mentioned. He begins Avith obferving, that of the light refleded from mercury, one fourth at leaft is loft, and that pro¬ bably no fubftances refled more than this. The rays Avere received at an angle of ii-J degrees of incidence, that is meafured from the furface of the refleding body, and not from the perpendicular, Avhich, he fays, is Avhat we are from this place to underfland whenever he men¬ tions the angle of incidence. ^5 With regard to the quantities of light refleded at Great dif- different angles of incidence, M. Bouguer found in ge-ferences in neral, that refledion is ftronger at fmall angles of-inci-^ere(^^ dence, and Aveaker at large ones. The difference is ex-0f fubftan- ceffive Avhen the rays ftrike the furface of tranfparent ces accord- fubftances, Avith different degrees of obliquity j but it is^'S t0 tlie almoft as great in foroe opaque fubftances, and it 'vasc^nce ^ always more or lefs fo in every thing that he tried. He found the greateft inequality in black marble, which, though not perfedly poliftied, yet Avith an angle of 30 35' of incidence, it refleded almoft as Avell as quick- filver. Of 1000 rays Avhich it received, it returned 600: but Avhen the angle of incidence Avas 140, it re- 51 fleded only 136; Avhen it was 30°, it refleded and Avhen it Avas 8o°, it refleded only 23. Similar experiments made with metallic mirrors al¬ ways gave the difterenecs much lefs confiderable. The greateft was 'hardly ever an eighth or a ninth part of it, but they were always in the fame Avav. The great difference betAveen the quantity of light refleded from the furface of Avater, at different angles of incidence, is truly furprifing. M. Bouguer fome- times fufpeded, that, when the angles of incidence were very OPT very fmall, the reflexion from water was even greater J than from quickfilver ; though he rather thought that it was fcarcely fo great. In very fmall angles, he fays, that water reflefts nearly ^ of the direft light. The light refledled from a lake is fometimes j- or or even a greater proportion, of the light that comes di¬ rectly from the fun, which is an addition to the direft rays of the fun that cannot fail to be very fenfible. The direCt light of the fun diminifhes gradually as it ap¬ proaches the horizon, while the reflected light at the fame time grows ftronger: fo that there is a certain al¬ titude of the fun, in which the united force of the di- reCt and reHeCted light will be the greateft poflible, and this he fays is 12 or 13 degrees. The light reflected from water at great angles of in¬ cidence is extremely fmall. M. Bouguer vras aflured, that, when the light was perpendicular, it reflected no more than the 37th part that quickfilver does in the fame cir cum fiances ; for it did not appear that water re¬ flects more than the 60th, or rather the 55th, part of perpendicular light. When the angle of incidence was 50°, the light reflected from the furface of water was about the 3 2d part of that which mercury reflected ; and as the reflection from water increafes as the angle of incidence diminifhes, it was twice as ftrong in proportion at 390 j for it was then the 16th part of the quantity re¬ flected from mercury. In order to procure a common ftandard by which to meafure the proportion of light reflected from various fluid fubflances, he feleCted water as the moft commo¬ dious *, and partly by obfervation and calculation he drew up the following table of the quantity of light re¬ flected from its furface at different angles of incidence. In the fame manner, he conftruCted the following table containing the quantity of light reflected from the looking glafs not quickfilvered. Angles of incidence. 2i 5 74 10 20 25 „RT.r( A"gi*-of fleCted of 8. P. Binoidence. IOOO. 584 543 474 412 356 299 222 157 30 40 5Q 60 70 80 90 Rays re¬ flected of ; 1000. 112 57 34 27 25 25 25 ICS.. *83 When water floats upon mercury there will be two Hiftory. images of any objeCt feen by reflection from them, one * " " v at the furface of the water, and the other at that of the quickfilver. In the largeft angles of incidence, the image at the furface of the water will difappear, which will happen when it is about a 60th or an 80th part lefs luminous than the image at the furface of the quickfilver. Deprefling the eye, the image on, the wa¬ ter will grow ftronger, and that on the quickfilver weaker in proportion ; till at laft, the latter will be in¬ comparably weaker than the former, and at an angle of about 10 degrees they will be equally luminous. Ac¬ cording to the table, tVoV incident rays are re¬ flected from the water at this angle of 10 degrees. At the furfaee of the mercury they w'ere reduced to 500 j and of thefe, part being reflected back upon it from the under furface of the water, only 333 remained, to make the image from the mercury. ^ It has been frequently obferved, that there is a remark- Reflection * ably flrong reflection into water, with refpeCt to rays of images ifluing from the water j and perfons under water have^y tkea^ feen images of things in the air in a manner peculiarly diftinCt and beautiful. In order to account for thefe faCts, M. Bouguer obferves that from the fmalleft angles of incidence, to a certain number of degrees, the greateft part of the. rays are reflected, perhaps, in as great a pro¬ portion as at the furface of metallic mirrors, or of quick¬ filver •, while the other part, which does not efcape into the air, is extinguifhed or abforbed ; fo that the furface of the tranfparent body appears opaque on the infide. If the angle of incidence be increafed only a few degtees, the ftrong reflection ceafes altogether, a great number of rays efcape into the air, and very few are abforbed. As the angle of incidence is farther increafed, the quantity . of the light reflected becomes lefs and Ids ; and when it is near 90 degrees, almolt all the rays efcape out of the tranfparent body* its furface lofing almoft all its power of reflection, and becoming nearly as tranfparent as when the light falls upon it from without. This property belonging to the furfaces of tranfpa-Extinction rent bodies, of abforbing the rays of light, is truly re-.of the rays markable, and, as there is reafon to believe, had not0^'^ at been noticed by any perfon before M. Bouguer. of tranf^ That all the light is reflected at certain angles of in-rentab0dies. cidence from air into denfer fubftances, had frequently 38 been noticed, efpecially in glafs prifms ; fo that New-Stroi?g re‘ ton made’ufe of one of them, inftead of a mirror, in the^6^011 '>y - - - - - 7 * pnfm. conftfuCtion of his reflecting telefcope. If a beam of'* light fall upon the air from within thefe prifms, at an angle of 10, 20, or 30 degrees, the die it will be nearly the fame as at the furface of quickfilver, one-fourth or one-third of the rays being extinguifhed, and two-thirds or three-fourths reflected. This property retains its full force as far as an angle of 490 49', (the proportion of the fines of the refraCtion being 3 i and 20) ; but if the angle of incidence be increafed but one degree, the quantity of light reflected inwards fuddenly deereafes, and a great part of the rays efcape out of the glafs, fo that the furface becomes fuddenly tranfparent. All tranfparent bodies have the fame property, with this difference, that the angle of incidence at which the ftrong reflection eeafes, and at which the light which is not reflected is extinguifhed, is greater in fome than in others. In water this angle is about 410 32''; and in every medium it depends fo much on the invariable proportion c s. 184 OPT Hiftory, proportion of the fine of the angle of refra£Hon to the ¥ ~ ' fine of the angle of incidence, that this law alone is fufficient to determine all the phenomena of this new circumfiance, at leaft as to this accidental opacity of the furface. When M. Bougner proceeded to meafure the quanti¬ ty of light reflefted by thefe internal furfaces at great angles of incidence, he had to ftruggle with many dif¬ ficulties j but by ufing a plate of cryftal, he found, that at an angle of 75 degrees, this internal refle&ion dimi- nifhed the light 27 or 28 times j and as the external refleftion at the fame angle diminilhed the light only 26 times, it follows that the internal reflection is a little ftronger than the other. Repeating thefe experiments with the fame and dif¬ ferent pieces of cryftal, he fometimes found the two re¬ flexions to be equally ftrong 5 but, in general, the in- 39 ternal was the ftronger. O/the Refuming his obfervations on the diminution of light, jT'hi^ref occafi°ned by the reflection of opaque bodies obliquely fleCtad by fixated, he compared it with the appearances of fimilar different ” fubftances which reflected the light perpendicularly, fubftances. Ufing pieces of filver made very white, he found, that when one of them was placed at an angle of 75 degrees with refpeCt to the light, it reflected only 640 parts out of 1000. He then varied the angle, and alfo ufed white plafter and fine Dutch paper, and drew up the follow¬ ing table of the proportion of the light reflected from each of thofe fubftances at certain angles. Quantity of Light reflected from Angles of incidence. 90 75 60 45 30 *5 Silver. 1000 802 640 455 3T9 209 Plafter. 1000 762 640 529 352 194 Dutch Paper. 971 743 5°7 332 203 Suppofing the afperities of opaque bodies to confift of very fmall planes, it appears from thefe obferva¬ tions, that there are fewer of them in thofe bodies which refleCt the light at fmall angles of incidence than at greater. None of them had their roughnefs equivalent to fmall hemifpheres, which would have difperfed the light equally in all directions ♦, and, from the c/a/a in the preceding table, he deduces mathematically the number of the planes that compofe thofe furfaces, and that are inclined to the general furface at the angles above men¬ tioned, fuppofing that the whole furface contains 1000 of them that are parallel to itfelf, fo as to refleCl the light perpendicularly, when the luminous body is fituat- ed at right angles with refpeCl to it. His conclufions reduced to a table, correfponding to the preceding, are as follow’: I Inclinations of the fmall fur¬ faces with re- fpeCl to the large one. o !5 3° 45 60 75 The diftribution of the fmall planes that conftitute the af¬ perities of the opaque furface in the Silver. Plafter. 1000 777 554 333 161 53 1000 736 554 374 176 50 Pape IOOO 937 545 35S 166 52 Hiftory, Thefe variations in the number of little planes, he ex- preffes in the form of a curve ; and afterwards fhows, geometrically, what would be the efteCt if the bodies were enlightened in one direction, and viewed in ano¬ ther. Upon this fubjeCt he has feveral curious theorems and problems; but for thefe we muft refer to the work itfelf. 40 Since the planets are more luminous at their edges 91jl®rva' that at their centres, he concludes, that the bodiestlons.con* which form them are conftituted in a manner different from ours •, particularly that their opaque furfaces confift &c. of fmall planes, more of which are inclined to the ge¬ neral furface than they are in terreftrial fubftances j and that there are in them an infinity of points, which have exaftly the fame fplendour. M. Bouguer next proceeds to afeertain the quantity of furface occupied by the fmall planes of each particu¬ lar inclination, from confidering the quantity of light reflected by each, allowing thofe that have a greater in¬ clination to the common furface to take up proportion- ably lefs fpace than thofe which are parallel to it. And comparing the quantity of light that would be reflected by fmall planes thus difpofed, -with the quantity of light that was actually reflected by the three fubftances above mentioned, he found that plafter, notwithftanding its extreme whitenefs, abforbs much light j for that, of 1000 rays falling upon it, of which 166 or 167 ought to be reflected at an angle of 770, only 67 are in faCfc returned ; fo that 100 out of 167 were extinguilhed, that is, about three-fifths. With refpeCt to the planets, Bouguer concludes, that of 300,000 rays which the moon receives, 172,000, or perhaps 204,100, are abforbed. 4I Plaving confidered the furfaces of bodies as confiftingOf thefur- of planes only, he obferves that each fmall furface, fe-face.sof parately taken, is extremely irregular, fome of thembotlie** really concave, and others convex 5 but, in reducing them to a midale ftate, they are to be regarded as planes. Neverthelefs he confiders them as planes only with refpeCl to the reception of the rays; for as they are almoft all curves, and as, befides this, many of thofe whofe fituation is different from others contribute to the fame effeCts, the rays always iffue from an aCtual or imaginary focus, and after refleClion always diverge from another. The experiments of Lambert, related in his Photome- tna, have laid open to us many curious obfervations concerning the natural hiftory of light. He was the firft who determined that a radiating furface emits its light with nearly the fame intenfity in all directions, fo that OPT Hiftory 42 Mr Mel¬ ville’s ob- fervations on the manner in which bo¬ dies are heated by light. 43 Abbe i\Tol- •et’s experi- ments with burning glafles. tlrat every portion of it appears equally bright to an ob- ferver placed in any direction. ° W e ate obliged to Mr Pi/Ielville for fume ingenious obfervations on the manner in which bodies are heated by light. He obferves, that, as each colorific particle of an opaque body mull be fomewhat moved by the refle&ion of the particles of light, when it is reflected backwards and forwards between the fame particles, it is manifeft that they muft likewife be agitated with a vibratory motion, and the time of a vibration will be equSl to that which light takes up in moving from one particle of a body to another adjoining. This dillance, in the molt folid opaque bodies, cannot be fuppofed greater than TT^th of an inch, which fpace drRfcrlbf3 5n the T^ToOOo4o000O00tb Of a fecond. With lo rapid a motion, therefore, may the internal parts of bodies be agitated by the influence of light, as to perform 1 25,000,000,000,000 vibrations, or more, in a fecond of time. The arrival of different particles of light at the fur- face of the fame colorific particle, in the fame or dif¬ ferent rays, may difturb the regularity of its vibrations, but will evidently increafe their frequency, or raife Hill fmaller vibrations among the parts which compofe thofe particles ; whence the inteftine motion will be¬ come more fubtle, and more thoroughly diffufed. If the quantity of light admitted into the body be increafed, the vibrations of the particles muft likewife increafe in magnitude and velocity, till at laft they may be fo violent, as to make all the component particles dafh one another to pieces by their mutual collifion ; in which cafe, the colour and texture of the body muft be de- ftroyed. Since there is no refle&ion of light but at the fur- face of a medium, the fame gentleman obferves, that the greateft quantity of rays, though crowded into the fmalleft fpace, will not of themfelves produce any heat. Hence it follows, that the portion of air which lies in the focus of the molt potent fpeculum, is not at all af¬ fected by the paffage of light through it, but continues of the fame temperature with the ambient air ; though any opaque body, or even any tranfparent body denfer than air, when put in the fdme place, would, in an in- ftant, be intenfely heated. I he eafieft way to be fatisfied of this truth experi¬ mentally is, to hold a hair, or a piece of down, imme¬ diately above the focus of a lens or fpeculum, or to blow a ftream of finoke from a pipe horizontally over it 5 for if the air in the focus were hotter than the furrounding fluid, it would continually afcend on account of its ra¬ refaction, and thereby fenfibly agitate thofe flender bo¬ dies.^ Or a lens may be fo placed as to form its focus ■within a body of water, or feme other tranfparent fub- ftance, the heat of which may be examined from time to time with a thermometer j but care muft be taken, m this experiment, to hold the lens as near as poflible to the tranfparent body, left the rays, by falling clofer than ordinary on its fur face, fliould warm it more than the common funbeams. See Prieftley on Vifion. I he attempts of the Abbe Nollet to fire inflam¬ mable fubflances by the concentration of the folar rays have a near relation to the prefent fubjeCf. He attempt¬ ed to fire liquid fubftances, but he was not able to do it either with fpirit of wine, olive oil, oil of turpentine, or ether yind though he could fire fulphur, yet he could Vol. XV. Part I. I C S. not fucceed with Spanifli wax, rofin, black pitch, or fuet. He both threw the focus of thefe mirrors upon the fub¬ ftances themfelves, and alfo upon the fumes that rofe from them ; but the only effect was, that the liquor boiled, and was difperfed in vapour or very fmall drops. When linen rags, and other folid fubftances, were moift- ened with any of thefe inflammable liquids, they would not take fire till the liquid was difperfed in a copious fume ; fo that the rags thus prepared were longer in burning than thofe that were dry. 4i M. Beaume, who aflifled M. Nollet in fome of thefe M. Beau- experiments, obferved farther, that the fame fubftances me’s expe- which were eafily fired by the flame of burning bodies,nments- could not be fet on fire by the contaft of the hotteft bo¬ dies that did not a&ually flame. Neither ether nor fpi¬ rit of wine could be fired with a hot coal, or even red- hot iron, unlefs they were of a white heat. By the help of optical principles, and efpecially by Bodies obfervations on the refle&ion of light, Mr Melville de- which feem monftrated that bodies which feem to touch one anothert0 touch are not always in a&ual contaft. Upon examining the therTre" volubility and luftre of drops of rain that lie on the nothTac- leaves of colewort, and fome other vegetables, he found tual con- that the luftre of the drop is produced by a copious re- flection of light from the flattened part of its furface contiguous to the plant. He found alfo, that, when the drop rolls along a part which has been wetted, it imme¬ diately lofes all its luftre, the green plant being then feen clearly through it 5 whereas, in the other cafe, it is hardly to be dilcerned. From thefe two obfervations, he concluded, that the drop does not really touch the plant, when it has the mercurial appearance, but is fufpended in the air at fome diftance from it by a repulfive force. For there could not be any copious refle&ion of white light from its un¬ der furface, unlefs there were a real interval between it and the furface of the plant. If that furface were perfeftly fmooth, the under furface of the drop would be fo likewife, and would therefore fliow an image of the illuminating body by reflexion, like a piece of poliflied filver ; but as it is confiderably rough, the under furface becomes rough likewife, and thus by reflecting the light copioully in different directions, affumes the brilliant hue of unpo- liflied filver. It being thus proved by an optical argument, that the drop is not really in contaft with the leaf, it may eafily be conceived whence its volubility arifes, and why it leaves no moifture where it rolls. Before we conclude the hiltory of the obfervations concerning the reflection of light, we muft not omit to,ious niif_ take notice of two Angular mifcellaneou? obfervations. cellaneouS Baron Alexander Funk, vifiting fome filver mines in°Uerva- Sweden, obferved, that, in a clear day, it was as dark as'10115, pitch below ground, in the eye of a pit, at 60 or 70 fa¬ thoms deep •, whereas, in a cloudy or rainy day, he could even fee to read at the depth of ic6 fathoms. He ima¬ gined that it arofe from this circumftance, that when the atmofphere is full of clouds, light is reflefted from them into the pit in all directions, and that thereby a con- fiderable proportion of the rays is reflected perpendicular¬ ly upon the earth 5 whereas, when the atmofphere is clear, there are no opaque bodies to refleCt the light in this man¬ ner, at leaft in a fufficient quantity ; and rays from the fun itfelf can never fall perpendicularly in that country. A a The i86 ° P T Hiftory. The other obfervation was that of the ingenious Mr ' Grey. He took a piece of ftiff brown paper, and prick¬ ing a fmall hole in it, he held it at a little diftance be¬ fore him ; when, applying a needle to his eye, he was furprifed to fee the point of it inverted. The nearer the needle was to the hole, the more it was magnified, but the lefs diitindl ; and if it was fo held, that its image was near the edge of the hole, its point feemed crooked. From thefe appearances he concluded, that thefe fmall holes, or fomething in them, produce the effedls of con¬ cave fpeculums ; and from this circumflance he took the liberty to call them aerial fpeculums. This method of accounting for the inverted image of the pin is evidently erroneous j for the fame effedl is pro¬ duced, when the fmall aperture is formed of two femi- apertures at different diilances from the eye, or when a fmall opening is made in the pigment on a piece of fmoked glafs. We have found indeed that the fame phenomenon rvill appear, if, inflead of looking at a hole in a piece of paper, we view a fmall luminous point fo that it is expanded by indiftindl vifion into a circular image of light. The pin always increafes in magnitude in proportion to its diftance from the luminous point. Sect. III. Difcoveries concerning the Injle Elion of Light. This property of light was not difcovered till about the middle of the 17th century. The perfon who firft made the difcovery was Father Grimaldi } at leaft he firft publifned an account of it in his treatife L)e lu- tnine, coloribu?, et inde, printed in 1666. Dr Hooke, however, laid claim to the fame difcovery, though he did not make his obfervations public till fix years after Grimaldi. Dr Hooke’s Dr Hooke having darkened his room, admitted a diicovexies. beam of the fun’s light through a very fmall hole in a brafs plate. This beam fpreading itfelf, formed a cone, the vertex of which was in the hole, and the bafe was on a paper, fo placed as to receive it at fome diftance. In the image of the fun, thus painted on the paper, he obferved that the middle was much brighter than the edges, and that there was a kind of dark penumbra about it, of about a 16th part of the diameter of the circle ; which he aferibed to a property of light, that he promifed to explain.—Having obferved this, at the diftance of about two inches from the former he let in another cone of light ; and receiving the bafes of them, at filch a diftance from the holes that the circles in- Plate terfefled each other, he obferved that there was not on- CCCLXXV. ly a darker ling, encompaffing the lighter circle, but a Tig. 6. manifeft dark line, or circle, as in fig. 6. which appear¬ ed even where the limb of the one interfered with that of tlie other. In the light thus admitted, he held an opaque body Fig. 7.. fig. 7. fo as to intercept the light that entered at a hole in the window fhutter O, and was received on the fcreen AP. In thefe circumftances, he obferved, that the (hadow of the opaque body (which was a round piece of wood, not bright or polifhed) was all over fomewhat enlightened, but more efpecially towards the edge. In order to (how that this light was not produ¬ ced by reflection, he admitted the light through a hole burnt in a piece of pafteboard, and intercepted it with a razor which had a very (harp edge ■, but ftill the ap¬ pearances were the very fame as before $ fo that he con- 3 I c s. eluded that they were occafioned by fome new property Hiftory, of light. u“—Y—-■< Pie diverfified this experiment, by placing the razor fo as to divide the cone of light into two parts, and placing the paper fo that none of the enlightened part of the circle fell upon it, but only the ftiadow of the razor j and, to his great furprife, he obferved what he calls a very brifk and vifible radiation ftriking down up¬ on the paper, of the fame breadth with the diameter of the lucid circle. This radiation always ftruck perpen¬ dicularly from the line of ftiadow, and, like the tail of a comet, extended more than 10 times the breadth of the remaining part of the circle. He found, wherever there was a part of the interpofed body higher than the reft, that, oppoiite to it, the radiation of light into the ftiadow was brighter, as in the figure ; and wherever there was a notch or gap in it, there rvould be a dark ftroke in the half-enlightened fliadow. From all thefe appearances, he concluded, that there is a deflefrion of light, differing both from reflection and refra&ion, and feeming to depend on the unequal denfity of the conftituent parts of the ray, whereby the light is dil- perfed from the place of condenfation, and rarefied, or gradually diverged into a quadrant •, that this defleftion is made towards the fuperficies of the opaque body per¬ pendicularly •, that thofe parts of the diverged radiations which are defleCted by the greateft angle from the ftraight or diredt radiations are the fainteft, and thofe that are defledled by the leaft angles are the ftrongeft y that rays cutting each other in one common aperture do not make the angles at the vertex equal 5 that colours may be made without refradlion ; that the diameter of the fun cannot be truly taken with common fights ; that the fame rays of light, falling upon the fame point of an object, will turn into all forts of colours, by the va¬ rious inclinations of the objedl; and that colours begin to appear when two pulfes of light are blended fo well, and fo near together, that the fenfe takes them for one. . 4s . We (hall now proceed to give an account of the dif- Grimaldi’s coveries of Father Grimaldi. Having introduced a ray ^ftco',er'es‘ of light, through a very fmall hole, AE, fig. 8. into a 8- darkened room, he obferved that the light wras diffufed in the form of a cone, the bafe of which was CD •, and that if any opaque body, FE, was placed in this cone of light, at a confiderable diftance from the hole, and the ftia¬ dow received upon a piece of white paper, the boundaries of it were not confined within GH, or the penumbra IL, occafioned by the light proceeding from different parts of the aperture, and of the dilk of the fun, but extended to MN : At this he was very much furprifed, as he found that it was broader than it ought to have been made by rays palling in right lines by the edges of the objeft. But the moft remarkable circumftance in this ap¬ pearance was, that upon the lucid part of the bale, CM and ND, ftreaks of coloured light were plainly diftinguifhed, each being terminated by blue on the fide next the ftiadow, and by red on the other j and though thefe coloured ftreaks depended, in fome meafure on the fize of the aperture AB, becaufe they could not be made to appear if it was large, yet he found that they were not limited either by it, or by the diameter of the fun’s dilk. He farther obferved, that thefe coloured ftreaks were Fig. p Fig. 10. OPT Hiftory. were not all ot the fame breadth, but grew narrower as ““'"V—they receded from the fhadow, and were each of them broader the farther the fhadow was received from the opaque body, and alfo the more obliquely the paper on which they were received was held with refpeft to it. He never obferved more than three of thefe flreaks. To give a clearer idea of thefe coloured ftreaks, he drew the reprefentation of them, exhibited in fig. 9. in which NMO reprefents the largeft and moft luminous flreak, next to the dark fiiadow X. In the fpace in which M is placed there was no diftin&ion of colour, but the fpace NN was blue, and the fpace OO on the other fide of it was red. The fecond ftreak QPR was narrower than the former ; and of the three parts of which it confided, the fpace P had no particular colour, but £)£) was a faint blue, and RR a faint red. The third Itreak, TSV, was exatdly fimilar to the two others, but narrower than either of them, and the colour dill fainter. Thefe coloured dreaks he obferved to lie parallel to the fhadow of the opaque body ; but when it was of an angular form, they did not make the fame acute an¬ gles, but were bent into a curve, the outermod being rounder than thofe that were next the fhadow, as is re- prefented in fig. 10. If it was an inward angle, as DCH, the coloured dreaks, parallel to each other of the two fides eroded without obliterating one another ; only the colours were thus rendered either more intenfe or mixed. W ithin the diadow itfelf, Grimaldi fometimes per¬ ceived coloured dreaks, fimilar to thofe above mentioned on the outfide of the diadow. Sometimes he faw more of them, and fometimes fewer ; but for this purpofe it was necedary to have drong light, and to make the opaque body long and moderately broad. A hair, for indance, or a fine needle, did not anfwer fo well as a thin and narrow plate : and the dreaks were mod dif- tingui(liable when the fhadow was taken at the greated didance; though the light grew fainter in the fame pro¬ portion. The numbers of thefe dreaks increafed with the breadth of the plate. They were at lead two, and fometimes four, if a thicker plate were made ufe of. But, with the fame plate, more or fewer dreaks appear¬ ed, in proportion to the didance at which the diadow was received 5 but they were broader when they were few, and narrower when there were more of them; and they were all much more didintt when the paper was held obliquely. Thefe coloured dreaks, like thofe on the outfide of the diadow, were bent in an arch, round the acute an¬ gles of the diadow, as they are reprefented in fig. 11. At this angle alfo, as at D, other fhorter lucid dreaks were vifible, bent in the form of a plume, as they are drawn betwixt D and C, each bending round and meet- ing again in D. Thefe angular dreaks appeared, though the plate or rod was not wholly immerfed in the beam of light, but the angle of it only ; and they increafed in number with the breadth of the plate. If the plate was very thin, the coloured dreaks bent round from the oppofite fides, and met one another as at B. In order to obtain a more fatisfa£Iory proof, that rays of light really bend, in pading by the edges of bo- 1 8-7 fig-11 I c s. dies, he admitted a beam of light into a dark room, as Hiftory. before j and, at a great didance from it, he fixed a plate v (fig. 1 2.) with a fmall aperture GH, which admit-I2, ted only a part of the beam of light, and found, that when the light tranfmitted through this plate was re¬ ceived at fome diitance upon a white paper, the bafe IK was confiderably larger than it could podibly have been made by rays ilfuing in right lines through the two a- pertures. Grimaldi generally made the aperture CD tso or Part °fa foot, and the fecond aperture, GH, tsV or Totr ? an light, was pretty ftrong for the fpace ol about ^ of an inch, eir 4 of an inch, and gradually decreafed till it became infenfible. The whole length of either of thefe ftreams, mea- fured upon the paper, at the diftance of 3 feet from the knife, was about 6 or 8 inches •, fo that it lubtend¬ ed an angle, at the edge of the knife, of abend 10 or 12, or at moft 14, degrees. Yet fometimes he thought he faw it ftioot 3 or 4 de grees farther ; but with a light fo very faint, that he could hardly perceive it.' This light he lufpedted might, in part as kail, arife fremi fome other caufe than the two ftreams. For, placing his eye in that light, beyond the end of that ftream which was behind the knife, and looking towards the knife, he could lee a line of light upon its edge ; and that not only when his eye was in the line of the ftreams, but alfo when it was out of that line, either towards the point of the knife, or towards the handle. 1 his line of light appeared contiguous to the edge of the knife, and was narrower than the light of the inner- moll fringe, and narrowelt when his eye was fartheft from the diredil light ; and therefore feemed to pals be¬ tween the light of that fringe and the edge of the knife j and that which pafled neareft; the edge feemed to be moft bent. He then placed another knife by the former, fo that their edges might be parallel, and look towards one another, and that the beam of light might fall upon both the knives, and fome part of it pafs between their edges. In this fituation he obferved, that when the diftance of their edges was about the 400th of an inch, the ftream divided in the middle, and left a lhadow between the two parts. This ftiadow was fo dark, that all the light which paffed between the knives feemed to be bent to the one hand or the other 5 and as the knives Hill approached each other, the ftiadow grew broader and the ftreams Ihorter next to it, till, upon the contafl of the knives, all the light.vaniftied. Hence Sir Ifaac concluded, that the light which is leaft bent, and which goes to the inward ends of the ftreams, paffes by the edges of the knives at the greateft .diftance j OPT Hiftory dhlance ; and this diftance, wlien the fliadow began to 1 appear between the itreams, was about the Sooth of an inch; and the light which paifed by the edges of the knives at didances ft ill lefs and lefs, was more and more faint, and went to thofe parts cf the ftreams which were farther from the direct light j becaufe, when the knives approached one another till they touched, thofe parts of the ftream vaniflied laft which were fartheft from the direfl line. In the experiment of one knife only, the coloured fringes did not appear ; but, on account of the breadth of the hole in the window, became fo broad as to run into one another, and, by joining, to make one continual light in the beginning of the ftreams ; but in the laft experiment, as the knives approached one another, a little before the ftiadow appeared between the two ftreams, the fringes began to appear on the inner ends of the ftreams, on either fide of the diredf light 5 three on one fide, made by the edge of one knife, and three on the other fide, made by the edge of the other knife. They were the moft diftinct when the knives were placed at the greateft diftanee from the hole in the win¬ dow, and became ftill more diftinct by making the hole lefs •, fo that he Could fometiraes fee a faint trace of a fourth fringe beyond the three above mentioned : and as the knives approached one another the fringes grew more diftinit and larger, till they vanished ^ the outer- moft vanififing firft, and the innermoft laft. After they avere all vanifhed, and the line of light in the middle between them was grown very broad, extending itfelf on both fides into the ftreams of light deferibed before, the above-mentioned ftiadow began to appear in the middle of this line, and to divide it along the middle into two lines of light, and increafed till all the light vanifhed. This enlargement of the fringes was fo great, that the rays which went to the innermoft fringe feem- ed to be bent about 20 times more when the fringe was ready to vanifti, than when one of the knives was taken away. From both thefe experiments Newton concluded, that _ the light of the firft fringe paffed by the edge of the knife at a diftance greater than the 800th of an inch } that the light of the fecond fringe pafted by the edge of the knife at a greater diftance than the light of the firft fringe, and that of the third at a greater diftance than that of the fecond ; and that the light of which the ftreams above mentioned confifted, palled by the edges of the knives at lefs diftances than that of any of the fringes. He then got the edges of two knives ground ftraight, and fixed their points into a board, fo that their edges might contains rectilinear angle. The diftance of the edges of the knives from one another, at four inches from the angular point, was the 8th of an inch •, fo that the angle contained by their edges was about i° 54'. The knives being thus fixed, he placed them in a beam of the fun’s light let into his darkened chamber, through a hole the 4 2d of an inch wide, at the diftance of 10 or 13 feet from the hole ^ and he let the light which paf¬ fed between their edges fall very obliquely on a fmooth white ruler, at the diftance of \ inch, or an inch, from thij knives 5 and there he faw the fringes made by the two edges of the knives run along the edges of the fha- dows of the knives, in lines parallel to thofe edges, with- I c s. out growing fenfibly broader, till they met in angles Hiftory. equal to the angle contained by the edges of the knives j y—— and where they met and joined, they ended, without crofting one another. But if the ruler was held at a much greater diftance from the knives, the fringes, where they were farther from the place of their meet¬ ing, were a little narrower, and they became fomething broader as they approached nearer to one another, and after they met they crofted one another, and then be¬ came much broader than before. From thefe obfervations he concluded, that the di¬ ftances at which the light compofing the fringes pafled by the knives were not increafed, or altered by the ap¬ proach ; and that the knife which was neareft to any ray determined which v7ay the ray ftiould be bent, but that the other knife increafed the bending. When the rays fell very obliquely upon the ruler, at the diftance of \ of an inch from the knives, the dark line between the firft and fecond fringes of the fhadow of one knife, and the dark line between the firft and fe¬ cond fringe of the fhadow of the other knife, met one another, at the diftance of ^ of an inch from the end of the light which paiTed between the knives, where their edges met; fo that the diftance of the edges of the knives, at the meeting of the dark lines, rvas the 160th of an inch ; and one half of that light pafled by the edge of one knife, at a diftance not greater than the 320th part of an inch, and, falling upon the paper, made the fringes of the fhadow oi that knife; while the other half pafled by the edge of the other knife, at a diftance not greater than the 320th part of an inch, and, falling upon the paper, made the fringes -of the fhadow of the other kniie. But if the paper was held at a diftance from the knives greater than ^ of an inch, the dark lines above mentioned met at a greater diftance than -f of an inch from the end of the fight which pafled be¬ tween the knives, at the meeting of their edges j fothat the light which fell upon the paper where thofe dark lines met pafled between the knives, where their edges were farther diftant than the 160th of an inch. For at another time, when the two knives were 8 feet 5 inches from the little hole in the window, the light which fell upon the paper where the above mentioned dark lines met pafled between the knives, where the diftance be¬ tween their edges was, as in the following table, at the diftances from the paper noted. Diftance of the paper from the knives in inches. Diftance between the edges of the knives in thoufandth parrs of an inch. 3t 8f 32 96 I3r 0,0 r 2 0,020 0,054 0,057 0,081 0,087 From thefe obfervations he concluded, that the light which forms the fringes upon the paper is not the fame light at all diftances of the paper from the knives; but that when the paper is held near the knives, the fringes are made by light which pafles by the 5 9° Hiftory. Plate ■CCCLXXVI fig. 2. OPT the edges of the knives at a let's diftance, and is more bent than when the paper is held at a greater diiiance from the knives. When the fringes of the tliadows of the knives fell perpendicularly upon the paper, at a great dillance from the knives, they were in the form of hyperbolas, of the following dimentions. Let CA, CB, (fig. 2.) reprefent lines drawn upon the paper, parallel to the edges of the ' knives j and between which all the light would fall if it fuffered no inflection. DE is a right line drawn through C, making the angles A CD, BCE, equal to one an¬ other, and terminating all the light which falls upon the paper, from the point where the edges of the knives meet. Then e z /, and g / v, will be three hy¬ perbolic lines, reprefenting the boundaries of the flia- dow of one of the knives, the dark line between the firtl and fecond fringes of that fhadow, and the dark line between the fecond and third fringes of the fame tha- dow. Alfo # z’p, y £ <7, and z/r, will be three other hyperbolic lines, reprefenting the boundaries of the tha- dow of the other knife, the dark line between the firtl and fecond fringes of that fhadow, and the dark line between the fecond and third fringes of the fame lhadow. Thefe three hyperbolas which are fimilar, and equal to the former, crofs them in the points z, k, and /; fo that the fhadows of the knives are terminated, and diftin- guifhed from the firfl: luminous fringes, by the lines e is and x z p, till the meeting and eroding of the fringes ; and then thofe lines crofs the fringes in the form of dark lines terminating the firfl: luminous fringes on the infide, and diflinguilhing them from another light, which begins to appear at z", and illuminates all the triangular fpace zp DE j1, comprehended by thefe dark lines and the right line DE. Of thefe hyperbolas one afymptote is the line DE, and the other afymptotes are parallel to the lines CA and CB. Before the fmall hole in the window Newton placed a prifm, to form on the oppofite wall the coloured image of the fun *, and he found that the fhadowrs of all bodies held in the coloured light, were bordered with fringes of the colour of the light in which they were held ; and he found that thofe made in the red light were the lar- geft, thofe made in the violet the leaft, and thofe made in the green of a middle bignefs. The fringes with which the fhadow of a man’s hair were furrounded, be¬ ing meafured acrofs the fhadow, at the didance of fix inches from the hair, the diftance between the middle and moft luminous part of the firft or innermoft fringe on one fide of the fhadow, and that of the like fringe on the other fide of the fhadow, wras, in the full red —^— of an inch, and in the full violet -S-g. The 37*5 like diftance betwreen the middle and moft luminous parts of the fecond fringes, on either fide of the fhadow, was in the full red light -g-V, and in the violet ?tt of an inch •, and thefe diftances of the fringes held the fame proportion at all diftances from the hair, without any fenfible variation. From thefe obfervations it was evident, that the rays which formed the fringes in the red light, pafled by the hair at a greater diftance than thofe which made the like fringes in the violet; fo that the hair, in caufing thefe fringes, afted alike upon the red light or leaft refran¬ gible rays at a greater diftance, and upon the violet or I c s. moft refrangible rays at a lefs diftance ; ana thereby oc- t Hiftoiy, cafloned fringes of different fizes, without any change in the colour of any fort of light. It may therefore be concluded, that when the hair was held in the white beam of light, and caft a fhadow bordered with three coloured fringes, thofe colours arofe not from any new modifications impreffed upon the rays of light by the hair, but only from the various inflexions by which the feverai forts of rays were fepa- rated from one another, which before feparation, by the mixture of all their colours, compofed the white beam of the fun’s light j but, when feparated, compofed lights of the feverai colours which they are originally difpofed to exhibit. The perfon who firft made any experiments fimilar to Marakfi’s thofe of NeWton on infleXed light is M. Maraldi. His Xfcoveries. obfervations chiefly refpeX the infleXion of light to¬ wards other bodies, whereby their fhadows are partially illuminated. He expofed in the light of the fun a cylinder ofEsi:ie5rj_ Wood three feet long, and 6^ lines in diameter, when ments con¬ its fhadow was everywhere equally black and well de-cermng the fined, even at the diftance of 23 inches from it. At a ^ greater diftance the fhadow appeared of two difterent y denfities; for its two extremities, in the direXion of the length of the cylinder, were terminated by two dark ftrokes, a little more than a line in breadth. Within thefe dark lines there was a faint light, equally difper- fed through the fhadow, which formed an uniform pen¬ umbra, much lighter than the dark ftrokes at the ex¬ tremity, or than the ftiadow received near the cylinder. This appearance is reprefented in Plate CCCLXXVI. fig. 3. < _ 3- As the cylinder was removed to a greater diftance from the paper, the twm black lines continued to be nearly of the fame breadth, and the fame degree of ob- feurity ; but the penumbra in the middle grew lighter, and its breadth diminifhed, fo that the tvro dark lines at the extremity of the ftiadow approached one another, till at the diftance of 60 inches, they coincided, and the penumbra in the middle entirely vanifhed. At a ftill greater diftance a faint penumbra was vifible ; but it vras ill defined, and grew broader as the cylinder was removed farther off, but was fcnfible at a very great di¬ ftance. Befides the black and dark fhadow which the cylin¬ der formed near the opaque body, a narrow and faint penumbra was feen on the outfide of the dark ftiadow. And on the outfide of this there was a traX more ftrong- ly illuminated than the reft of the paper. The breadth of the external penumbra increafed with the diftance of the ftiadow from the cylinder, and the breadth of the traX of light on the outfide of it wTas alfo enlarged ; but its fplendour diminifhed with the di¬ ftance, He repeated thefe experiments with three other cy¬ linders of different dimenfions ; and from all of them he inferred, that every opaque cylindrical body, expofed to the light of the fun, makes a fhadoiv which is black and dark to the diftance of 38 to 45 diameters of the cylinder which forms it ; and that, at a greater di¬ ftance, the middle part begins to be illuminated in the manner deferibed above. In explaining thefe appearances, Maraldi fuppofes that OPT Hiftory. that the light which diluted the middle part of the flia- u—v ' dow was occafioncd by the inflexion of the rays, which, bending inwards on their near approach to the body, did at a certain diftance enlighten all the fhadow, ex¬ cept the edges, which were left undifturbed. At the fame time other rays were deflefted from the body, and formed a ftrong light on the outfide of the (liadow, and which might at the fame time contribute to dilute the outer fhadow, though he fuppofed that penumbra to be occafloned principally by that part of the paper not being enlightened, except by a part of the fun’s difk only, according to the known principles of optics. 54 • ^ h® fame experiments he made with globes of feveral thXrS diameters •, but he found, that the fhadows of the globes. globes were not vifible beyond 15 of their diameters; which he thought was owing to the light being infiedl- ed on every fide of a globe, and confequently in fuch a quantity as to difperfe the fhadows fooner than in the cafe of the cylinders. In repeating the experiments of Grimaldi and New¬ ton, he obferved that, befides the enlarged fhadow of a hair, a fine needlg, &c. the bright gleam of light that bordered it, and the three coloured fringes next to this enlightened part, when the fhadow was at a confiderable diftance from the hair, the dark central fhadow was di¬ vided in the middle by a mixture of light; and that it was not of the fame denfity, except when if was very near the hair, A briftle, at the diftance of nine feet from the hole, made a fhadow, which, being received at five or fix feet from the objcdl, he obferved to confift of feveral ftreaks of light and fhade. The middle part was a faint fhadow7, or rather a kind of penumbra, bordered by a darker fhadow7, and after that by a narrower penum¬ bra ; next to which was a light ftreak broader than the dark part, and next to the ftreak of light, the red, violet, and blue colours were feen as in the fhadow,of the hair. A plate, two inches long, and about half a line cerningThe^0^’fixetl PerPendicularly to the rays, at the lhadowsof diform6 of nine feet from the hole, a faint light was feen uniformly difperfed over the fhadow, when it was received perpendicularly to it, and very near. The fhadow of the fame plate, received at the diftance of two feet and a half, was divided into four narrow black ftreaks, feparated by fmall lighter intervals equal to them. The boundaries of this fhadow on each fide had a penumbra, which was terminated by a very ftrong light, next to which were the coloured ftreaks of red, violet, and blue, as before. This is reprefented in Plate CCLXXVI. fig. 4. The fhadow7 of the fame plate, at 4^ feet diftance from it, was divided into two black ftreaks only, the two outermoft having difappeared, as in fig. 5. ; but thefe two black ftreaks which remained were broader than before, and feparated by a lighter fhade, twice as broad as one of the former black ftreaks, when the fha¬ dow was taken at 2y feet. This penumbra in the middle had a tinge of red. After the two black ftreaks there appeared a pretty ftrong penumbra, ter¬ minated by the two ftreaks of light, which were now broad and fplendid, after which followed the coloured ftreaks. A fecond plate, 2 inches long and a line broad, be- 55 Experi¬ ments con- plates. g-4- % 5* ICS. ing placed, 14 feet from the hole, its fhadow v7as re¬ ceived perpendicularly very near the plate, and was found to be illuminated by a faint light, equally difper¬ fed, as in the cafe of the preceding plate. But being received at the diftance of 13 feet from the plate, fix fmall black ftreaks began to be vifible, as in fig. 6. At Fig. 6, 17 feet the black ftreaks were broader, more diftinit, and more feparated from the ftreaks that were lefs dark. At 42 feet, only two black ftreaks were feen in the middle of the penumbra, as in fig. 7. This middle pen- umbra between the two black ftreaks wras tinged with red. Next to the black ftreaks there always appeared the ftreaks of light, which w7ere broad, and the coloured ftreaks next to them. At the diftance of 72 feet, the appearances were the fame as in the former fituation, except that the two black ftreaks w7ere broader, and the interval betw7een them, occupied by the penumbra, was broader alfo, and tinged with a deeper red. With plates from 4- line to 2 lines broad, he could not obferve any of the ftreaks of light, though the fhadows were in fome cafes 56 feet from them. The extraordinary fize of the fhadow's of fmall fub- ftances M. Maraldi thought to be occafioned by the fhadow from the enlightened part of the fky, added to that which was made by the light of the fun, and alfo to a vortex occafioned by the circulation of the inflected light behind the object. Maraldi having made the preceding experiments upon Angle long fubftances, placed two of them fo as to crofs one another in a beam of the fun’s light. The fhadows of two hairs placed in this manner, and received at fome diftance from them, appeared to be painted reciprocally one upon the other, fo that the obfcure part of one of them was vifible upon the obfcure part of the other. The ftreaks of light alfo crofted one another, and the coloured ftreaks did the fame. He alfo placed in the rays of the fun a briftle and a plate of iron a line thick, fo that they crofted one an¬ other obliquely • and when their fhadows were received at the fame diftance, the light and dark ftreaks of the fhadow of the briftle were vifible fo far as the middle of the fhadow of the plate on the fide of the acute angle, but not on the fide of the obtufe angle, whether the briftle or the plate were placed next to the rays. The plate made a fhadow fufficiently dark, divided into fix black ftreaks 5 and thefe w7ere again divided by as many light ones equal to them ; and yet all the ftreaks be¬ longing to the fhadow of the bridle were vifible upon it, as in fig. 8. To explain this appearance, he fuppofed Fig, g; that the rays of the fun glided a little along the briftle, fo as to enlighten part of that which was behind the plate. But this feems to be an arbitrary and improbable fuppofition. M Maraldi alfo placed fmall globes in the folar light, admitted through a fmall aperture, and compared their fhadow7s wdth thofe of the long fubftances, as he had done in the day light, and the appearances were ftill fi- milar. It was evident, that there was much more light in the fhadows of the globes than in thofe of the cylin¬ ders, not only when they were both of an equal diame¬ ter, but when that of the globe was larger than that of the cylinder, and the fhadows of both the bodies were received at the fame diftance. He alfo obferved, that he could perceive no difference of light in the fhadows of . coloured iTiadows. 57 M. Mai- ran’s the¬ ory. 392 ' . OPT Hiftory. Gf tlie p]ates wliich were a little more than one line *"'' broad, though they wei'e received at the diftance of 72 feet j but he could obferve a difference of (hades in thofe of the globes, taken at the fame diftance, though they were 2^ lines in diameter. In order to explain the colours at the edges of thefe ^5 fhadows, he threw fome 6f the fhadows upon others. Experi- He threw the gleam of light, which always intervened ments with between the colours and the darker part of the lhadow, a mixture of on different parts of other fhadows j and obferved, that, when it fell upon the exterior penumbra made by another needle, it produced a beautiful fky blue colour, almoft like that which was produced by two blue co¬ lours thrown together. When the fame gleam of light fell upon the deeper fliadow in the middle, it produced a red colour. He placed two plates of iron, each three or four lines broad, at a very fmall diftance : and having placed them in the rays of the fun, and received their fhadows at the diftance of 15 or 20 feet from them, he faw no light between them but a continued fhadotv, in the mid¬ dle of which were fome parallel ftreaks of a lively pur¬ ple, feparafed by other black ftreaks j but between them there were other ftreaks, both of a very faint green, and alfd of a pale yellow. The fubjedt of infleaion was next inveftigated by M. Mairan : but he only endeavoured to explain the fadts winch were known, by the hypothefis of an atmofphere furrounding all bodies ; and confequently making two refledlions and refradtions of the light that falls upon them, one at the furface of the atmofphere, and the other at that of the body. This atmofphere he fuppo- fed to be of a variable denfity and refradtive power, like the atmofphere. M. Du Tour thought the variable atmofphere fuper- fluous, and attempted to account for all the phenomena by an atmofphere of an uniform denfity, and of a lefs refradtive power than the air furrounding all bodies.. Only three fringes had been obferved by preceding authors, but M. Du Tour was accidentally led to ob¬ ferve a greater number of them, and adopted from Gri¬ maldi the follow'ing ingenious method of making them all appear very diftindt. He took a circular board ABED, (fig. 9.) 13 inches ‘in diameter, the furface of which w^as black, except at the edge, where there was a ring of white paper about three lines broad, in order to trace the circumference of a circle, divided into 36c degrees, beginning at the point A, and reckoning 180 degrees on each hand to the point E ; B and D being bach of them placed at 90 de- orees. A flip of parchment 3 inches broad, and difpo- fed in the form of a hoop, was faftened round the board, and pierced at the point E with a fquare hole, each fide being 4 or 5 lines, in order to introduce a ray of the fun’s light 5 and in the centre of the board C, he fixed a perpendicular pin about of a line in diameter. This hoop being fo placed, that a ray of light enter¬ ing the chamber, through a Vertical cleft of 2^ lines.in length, and about as wide as the diameter of the pin, went through the hole at E, and palling parallel to the plane of the board, projected the image of the fun and the fhadow of the pin at A. In thefe circumftances he obferved, 1. That quite round the concave furface of this hoop, there were a multitude of coloured ftreaks •, but that the fpace ?nAn, of about 18 degrees, the 58 . Difcovenes of M. Du Tour. Plate cccrfcxvi fig. 9. I c s. middle of which was occupied by the image of the fun, Hiftory. was covered with a faint light only. 2. The order of the colours in thefe ftreaks was generally fuch that the moft refrangible rays were the neareft to the incident ray EGA $ fo that, beginning from the point A, the violet was the firft and the red the laft colour in each of the ftreaks. In fome of them, however, the colours were difpofed in a contrary order. -3. The image of the fun, proje&ed on each fide of the point A, was divided by the lhadow of the pin, which w'as bordered by two luminous ftreaks. 4. The coloured ftreaks were nar- roAver in fome parts of the hoop than others, and gene¬ rally decreafed in breadth in receding from the point A. 5. Among thefe coloured ftreaks, there were fometimes others Avhich Avere white, 1 or ij lines in breadth, which Avere generally bordered on both fides by a ftreak of orange colour. From this experiment he thought it evident, that the rays which palled beyond the pin were not the only ones that Avere decompofed, for that thofe which were re- fiedled from the pin Avere decompofed alfo ; whence he concluded that they muft have undergone fome refrac¬ tion. He alfo imagined that thofe Avhich Avent beyond the pin fuffered a refte&ion, fo that they were all affeft- ed in a fimilar manner. 59 In order to give fome idea of his'hypothefis, M. Du Account of Tour (hows that the ray ab, fig. 10. after being refrabl- ed at by reflected at r and u, and again refraded at J ie ’ and ty Avill be divided into its proper colours *, the leaft 1 I0* refrangible or the red rays ifluing at x, and the moft re¬ frangible or violet at y. Thofe ftreaks in Avhich the co¬ lours appear in a contrary order he thinks are to be aferibed to inequalities in the furface of the pin. The coloured ftreaks neareft the ftiadoAV of the pin, he fuppofes to be formed by thofe rays which, entering the atmofphere, do not fall upon the pin 5 and, without any refledion, are only refraded at their entering and leaving the atmofphere, as at b and ru, fig. 11. In Fig. n this cafe, the red or leaft fefrangible rays Avill iffue at r, and the violet at u. To diftinguifti the rays which fell upon the hoop in any particular diredion, from thofe that came in any other, he made an opening in the hoop, as at P, fig. 9. by which means he could, with advantage, and at any diftance from the centre, obferve thofe rays unmixed with any other. 1 To account for the coloured ftreaks being larger next the fhadoAv of the pin, and groAving narroAver to the place where the light Avas admitted, he fhoAVS, by fig. 12. Fig. 12* that the rays a b are farther feparated by both the re- fradions than the rays c d. Sometimes M. Du Tour obferved, that the broader ftreaks were not difpofed in this regular order 5 but then he found, that by turning the pin they changed their places, fo that this circumftance muft have been an ac¬ cidental irregularity in the furface of the pin. The white ftreaks mixed Avith the coloured ones he aferibes to fmall cavities in the furface of the pin •, for they alfo changed their places Avlien the pin Avas turned upon its axis. He alfo found, that bodies of various kinds, and of different fizes, always produced fringes of the fame di- menfions. Expofing tAAro pieces of paper in the beam of light, fo that part of it paffed betAveen two planes formed by them* Fig. 13- 60 This hypo- thefis ufe- lefs and ill- founded. Hiftory. them, M. da Tour obferved, that the edges of this light were bordered with two orange ftreaks. To ac¬ count for them, he fuppofes, that the more refrangible of the rays which enter at b are fo refra£led, that they do not reach the furface of the body at R : fo that the red and orange light may be refledted from thence in the direction d M, where the orange ftreaks will be formed ; and, for the fame reafon, another ftreak of orange will be formed at m, by the rays which enter the atmofphere on the other fide of the chink. In a fimilar manner he accounts for the orange fringes at the borders of the white llreaks, in the experiment of the hoop. He fuppofes, that the blue rays, which are not refle&ed at R, pafs on to I ; and (hat thefe rays form the blue tinge obfervable in the fhadows of fome bodies. This, however, is mere trifling. We may here make a general obfervation, applicable to all the attempts of philofophers to explain thefe phe¬ nomena by atmofpheres, Thefe attempts give no expla¬ nation whatever of the phyfical caufe of the phenomena. A phenomenon is fome individual fadl or event in na¬ ture. We are faid to explain it, when we point out the general faft in which it is comprehended, and fhow the manner in which it is fo comprehended, or the particu¬ lar modification of the general fad!. Philofophy re- fembles natural hiltory, having for its fubjedt the events of nature •, and its inveftigations are nothing but the claflification of thefe events, or the arrangement of them Under the general fadls of which they are individual in- flances. In the prefent inftance there is no general fad! referred to. The atmofphere is a mere gratuitous fup- pofition *, and all that is done is to fhow a refemblance between the phenomena of infledlion of light to what would be the phenomena were bodies furrounded with fuch atmofpheres ; and even in this point of view, the difcuftions of Mairan and Du Tour are extremely defi¬ cient. They have been fatisfied with very vague refem- blances to a fad! obferved in one Angle inftance, and not fufficiently examined or defcribed in that inftance, name¬ ly, the refradlion of light through the atmofphere of this globe. The attempt is to explain how light is turned out of its diredlion by pafling near the furface of bodies. This indicates the adfion of forces in a diredlion tranf- verfe to that of the light. Newton took the right road of inveftigation, by taking the phenomenon in its origi¬ nal fimplicity, and attending merely to this, that the rays are defledfed from their former courfe; and the foie aim of his inveftigation was to difcover the laws, or the more general fadls in this defledlion. He deduced from the phenomena, that fome rays are more defledfed than others, and endeavoured to determine in rvhat rays the defied!ions are moft remarkable : and no experiment of M. du Tour has ftiown that he Was miftaken in his mo¬ dified affertion, that thofe rays are moft infledfed which pafs neareft to the body. We fay modified alfertion ; for Newton points out with great fagacity many in- ilahces of alternate fits of infledlion and defledlion ; and takes it for granted, that the law of continuity is obfer¬ ved in thefe phenomena, and that the change of inflec¬ tion into defledlion is gradual. But thefe analogical difcuflions are eminently deficient in another refpedl : Phey are held out as mechanical ex¬ planations of the.changes of motion obferved in rays of light. When it ftiall be ftiown, that thefe are precifely Vol. XV. Part I. 1 ' OPTICS. i9? fuch as are obferved in refracting atmofpheres, nothing Hiftory. is done towards deciding the original queftion ; for the v“—~v~“—^ action of refradling atmofpheres prefents it in all its dif¬ ficulties, and we mull ftill alk how do thefe atmofpheres produce this effedl ? No advance whatever is gained in fcience by thrufting in this hypothetical atmofphere ; and Newton did wifely in attaching himfelf to the fim- ple fad! : and he thus gives us another ftep in fcience,, 61. by fliowing us a fad! unknown before, viz. that the ac-^6^™' tion of bodies on light is not confined to tranfparent bo-andlnfiec- dies. He added another general fadt to our former tion pro- ftock, that light as well as other matter is aEled on at a bal)iy pro- diftdnce ; and thus he made a very important dedudlion,^10^1 by that reflection, refraction, and inflection, are probably forces”''' brought about by the fame forces. ^ M. Le Cat has well explained a phenomenon of vi-ObjecTs lion depending upon the infledtion of light, which (hows, fometimes that, in fome cafes objedts by this means appear magni-magnified fied. Looking at a diftant fteeple, Avhen a wire, of ab-y lnflec* lefs diameter than the pupil of his eye, was held near totl0n" it, and drawing it feveral times betwixt his eye and that objedl, he found, that, every time the wire paffed before bis pupil, the fteeple feemed to change its place, and fome hills beyond the fteeple appeared"to have the fame motion, juft as if a lens had been drawn belwixt his eye and them. He found alfo, that there was a polition of the wire in which the fteeple feemed not to have any motion, when the wire was paffed before his eye ; and in this cafe the fteeple appeared lefs diftindt and magni¬ fied. He then placed his eye in fuch a manner with re- fpedl to the fteeple, that the rays of light by which he law it mull come very clofe to the edge of a window, where he had placed himfelf to make his obfervations j and pafling the wire before Ids eyes, he obferved, that, when it was in the vifual axis, the fteeple appeared near¬ er to the window, on whichever fide the wire was made to approach. He repeated this experiment, and always, with the fame refult, the objedl being by this means mag¬ nified, and nearly doubled. This phenomenon he explains by fig. 14. in which B ^ate re prefents the eye, A the fteeple, and C a fedlion of the ccfiCLXixvr* wire. The black lines exprefs the cone of light by *S" ^ which the natural image of the fteeple A is formed, and which is much narrower than the diameter of the wire C 5 but the dotted lines include not only that cone of light, flopped and turned out of its courfe by the wire, but alfo more diftant rays infledled by the wire, and thereby thrown more converging into "the pupil ; juft as would have been the effedl of the interpofttion of a lens between the eye and the objedl. Sect. IV. Diflcoveries concerning Vijion. Maurolycus was the firft who demonftrated that the Difcoverie* cryftalline humour of the eye is a lens which colledls the of Mauro- light iffuing from external objedls, and converges them 1>rcus> KeP= upon the retina. He did not, however, feem to beler’ &ct aware that an image of every vifible objedl was thus c™cernin§ formed upon the retina, though this feems hardly to have V110n’ been a ftep beyond the dilcovery he had made. Mon- tucla conjedlures, that lie was prevented from mention¬ ing this part of the difcovcry by the difficulty of ac¬ counting for the upright appearance of objedls. This difcovery was made by Kepler; but he, too, was much puzzled with the mverfion of the image upon the rcfti- B b ns- 194- ilW.ary. OPTICS. d4 Difcovertes *>f Schemer 65 . Difco varies of Defcar- tes. na. The rechTcation of thefe images, he fays, is the bufmefs of the mind ; which, when it perceives an im- pfeffion on the lower part of the retina, confiders it as made by rays proceeding from the higher parts of ob- jefts ; tracing the rays back to the pupil, where they or of. one another. This is the true explanation of the difficulty, and is exactly the fame as that which was lately given by Dr Reid. Thefe difcoveries concerning'vifion were completed by Schemer. For, in cutting away the coats of the back part of the eyes of (Keep and oxen, and prefenting feveral objefts before them, he faw their images diftindt- ly painted upon the retina. He did the fame with the human eye, and exhibited this experiment at Rome in 1625. Scheiner took a good deal of pains to afcertam the denfity and refradlive power of all the humours of the eye, by comparing their magnifying power with that of water or glafs in the fame form and circumffances. Ihe refult of his inquiries was, that the aqueous humour does not differ much from water in this refpedt, nor the cry- Ralline from glafs ; and that the vitreous humour is a medium between both. He alfo traces the progrefs of the rays of light through all the humours , and after difcuffing every poffible hypothefis concerning the feat of vifion, he demonftrates that it is in the retina, and ihows that this was the opinion of Alhazen, Vitellio, Kepler, and all the moft eminent philofophers. He advances many reafons for this hypothefis j anfwers ma¬ ny obiedlions "to it 5 and, by a variety of arguments, re¬ futes the opinion that the feat of vifion is in the cryftal- line lens. _ . > - The fubjedt of vifion occupied the attention of Def- cartes. He explains the methods of judging of the magnitudes, fituations, and diftances, of objedts, by the diredlion of the optic axes ; comparing it to a. blind man’s judging of the fize and diftance of an objedl, by feeling it with two flicks of a known length, when the hands in which he holds them are at a known diftance from each other. He alfo remarks, that having been accuftomed to judge of tbe fituation of objedls by their images falling on a particular part of the eye ; if by any diftortion of the eye they fall on a different place, we are apt to miftake their fituation, or imagine one ob- jedl to be two, in the fame way as we imagine one flick to be two, when it is placed between two contiguous fingers laid acrofs one another. R he diredlion of the optic axes, he fays, will not ferve us beyond 15 or 20 feet, and the change of form of the cryftalline not more than three or four feet. For he imagined that the eye conforms itfelf to different diftances by a change in the curvature of the cryftalline, which he fuppofed to be a mufcle, the tendons of it being the ciliary proceffes. In another place, he fays, that the change in the conforma¬ tion of the eye is of no ufe to us for the purpofe of judging of diftances beyond four or five feet, and the angle of the optic axes not more than 100 or 200 feet: for this reafon, he fays, that the fun and moon are con¬ ceived to be much more nearly of the fame fize than they are in reality. White and luminous objefls, he ob- ferves, appear larger than others, and alfo the parts con¬ tiguous to thofe on which the rays aflually impinge *, and for the fame reafon, if the objefrs be fmall, and placed at a great diftance, they will always appear round, the figure of the angles difappearing. The celebrated Dr Berkeley, biftiop of Cloyne, pub- Hiftory. liftied, in 1709, An Eflay towards a New Theory of Vifion, in which he folves many difficulties. He does Eerkeley,s not admit that it is by means of thofe lines and angles, theory of which are ufeful in explaining the theory of optics, that vifion. different diftances are eftimated by the fenfe of fight -, neither does he think that the mere direftion of the op¬ tic axes or the greater or lefs divergency of the rays of light are fufficient for this purpofe. “ I appeal (fays he) to experience, whether any one computes its diftanc-e by the bignefs of the angle made by the meeting of the two optic axes ; or whether he ever thinks of the great¬ er or lefs divergency of the rays which arrive from any point to his pupil: Nay, whether it be not perfectly impoftible for him to perceive, by fenfe, the various angles wherewith the rays according to their greater or leffer divergency fell upon his eye.” That there is a neceffary connexion between thefe various angles, &c. and different degrees of diftance, and that this con¬ nexion is known to every perfon {killed in optics, he readily acknowledges ; but “ in vain (he obferves) fliall mathematicians tell me, that I perceive certain /ices and ang/es, which introduce into my mind the various no¬ tions of dijiance, fo long as I am confeious of no fuch thing.” He maintains that diftance, magnitude, and even figure, are the objefts of immediate perception on¬ ly by the fenfe of touch ; and that when we judge of them by fight, it is from different fenfations felt in the eye, which experience has taught us to be the confe- quence of viewing objefts of greater or lefs magnitude, of different figures, and at different diftances. Thefe fenfations, with the refpettive diftances, figures, and magnitudes by which they are occafioned, become fo clofely affociated in the mind long before the period. of diftinft recolle£tion, that the prefence of the one in- ftantly fuggefts the other 5 and we attribute to the fenfe of fight thofe notions which are acquired by the fenfe of touch, and of which certain vifual fenfations are merely the figns or fymbols, juft as words are the fymbols of ideas. Upon thefe principles he accounts for fingle and ereft vifion. Subfequent writers have made conlidera- ble difcoveries in the theory of vifion } and among them there is hardly any one to whom this branch of fcience is fo much indebted as to Dr Reid, and Dr Wells, whofe reafonings we {hall afterwards have occafion to detail. Sect. V. Of Optical Injlrutnents. Glafs globes, and fpeeula, feem to have been the «n- Invetfjon ly optical inftruments known to the ancients. Alhazen 0f fpedta- gave the firft hint of the invention of fpeftacles. From cles. the writings of this author, together with the obferva- tions of Roger Bacon, it is not improbable that fome monks gradually hit upon the conftruftion of fpeftacles ;. to which Bacon’s leffer fegment was a nearer approach than Alhazen’s larger one. It is certain that fpeflacles were well known in the 13th century, and not long before. It is laid that Alexander Spina, a native of Pifa, who died in 1313, happened to fee a pair of fpcflacles in the hands of a perfon who would not explain them to him ^ but that he fucceeded in making a pair for himfelf, and im¬ mediately made the conftrudftion public. It is alfo in- feribed on the tomb of Salvinus Armatus, a nobleman of Florence, who died 13x7, that he was the inventor of fpedlacles. TVmnoJi 60 Other ac counts. OPT Hlftory- Though both convex and concave lenfes were fuffi- -v—ciently common, yet no attempt was made to combine 6S s,s them into a telefcope till the end of the 16th century. ^tof Defeartes confiders James Metius as the firft conftrubfor the inven- of the telefcope : and fays, that as he was amufingJura¬ tion of tele-felf with mirrors and burning glaffes, lie thought of fcopes. looking through two of his lenfes at a time) and that happening to take one that was convex and another that was concave, and happening aifo to hit upon a pret¬ ty good adjuitment of them, he found, that, by looking through them, diltant objects appeared very large and diifinft. In fad, without knowing it, he had made a telefcope. Other perfons fay, that this great difeovery was firft made by John Lipperfheim, a fpedacle-maker at Mid- dleburgh, or rather by his children ; who were diverting themfelves with looking through two glades at a time, and placing them at different dillances from one another. But Borellus, the author of a book entitled De vero telefcopn inventore, gives this honour to Zacharias Joan- nides, i. e. Janlen, another fpedacle-maker at the fame place, who made the firft telefcope in 1590. This ingenious mechanic had no fooner found the ar¬ rangement of glaffes that magnified diftant objeds, than he enclofed them in a tube, and ran with his inftrument to Prince Maurice ; who, immediately conceiving that it might be ufeful in his wars, defired the author to keep it a fecret. But this was found impofiible ‘y and feveral perfons in that city immediately applied themfelves to the making and felling of telefcopes. One of the moft diftinguillied of thefe was Hans Laprev, called Lipper- Jheim by Sirturus. Some perfon in Holland being very early fupplied by him with a telefeope, he paffed with many for the inventor ; but both Metius above men¬ tioned, and Cornelius Drebell of Alcmaar, in Holland, applied to the inventor himfelf in 1620 ; as alfo did Galileo, and many others. The firft telefcope made by Janfen did not exceed 15 or 16 inches in length ; but Sirturus, who fays that he had feen it, and made •ne/ ^°0 U^e it the beft that he had ever exami¬ ned. Janfen dire&ing his telefcope to celeftial objeds, di- ftin&ly viewed the fpots on the furface of the moon j and difeovered many new ftars, particularly feven pretty confiderable ones in the Great Bear. His fon, Joannes Zacharias, obferved the lucid circle near the limb of the moon, from whence feveral bright rays feem to dart in different diredions : and he fays, that the full moon, viewed through this inftrument, did not appear flat, but was evidently globular. Jupiter appeared round, and rather fpherical j and fometimes he perceived two, fome- times three, and at other times even four fmall ftars, a little above or below him; and, as far as he could ob- ferve, they performed revolutions round him. There are feme who fay that Galileo was the inven¬ tor of telefcopes ; but he himfelf acknowledges, that he firft heard of the inftrument from a German; but, that being informed of nothing more than the effeds of it, firft by common report, and a few days after by a French nobleman, J. Badovere, at Paris, he himfelf difeovered the conftrudion, by confidering the nature of refradion: and thus he had much more real merit than the inventor himfelf. About April or May, in 1609, it was reported at Venice, where Galileo (who was profeffor of mathema- 70 The lirlt telefcope an exceed A telefcope fnade by Galileo without feeing one. account of I c s. tics in the univerfily of Padua) then happened to be, that a Dutchman had prefented to Count Maurice oi Naffau, a certain optical inttrument, by means of which, diftant objeds appeared as if they were near; but no h:S difeo, farther account of the difeovery had reached that place, veries, though this was near 20 years after the firft dilcovtry of the telefcope. Struck, however, with this account, Ga¬ lileo returned to Padua, confidering what kind oi an inftrument this muft be. The night following, the con¬ ftrudion occurred to him; and the day after, putting the parts of the inftrument together, as he had previous¬ ly conceived it; and notwithftanding the nnpertedion of the glaffes that he could then procure, the effed an- fwered his expedations, as he prekptly acquainted his friends at Venice, where, from feveral eminences, he fhowed to fome of the principal fenators of that repu¬ blic a variety of diftant objects, to their very great aito- niihment. When he had made farther improvements in the inftrument, he made a preient of one ot them to the Doge, Leonardo Donati, and at the fame time to all the fenate of Venice ; giving along with it a written paper, in which he explained the ftrudure and wonderful ufes that might be made of the inftrument both by land and fea. In return for fo noble an entertainment, the re¬ public, on the 25th of xVuguft, in the fame year, more than tripled his falary as profeffor. Galileo having amufed himfelf for feme time with the view of terreftrial objeds, at length diredeed his tube towards the heavens ; and found, that the I'urface of the moon was diverfified with hills and valleys, like the earth. He found that the miky way and nebulce con¬ fided of a colledion of fixed ftars, which on account either of their vaft diftance, or extreme fmallnefs, were invifible to the naked eye. Pie alfo difc9Vered innume¬ rable fixed ftars difperfed over the face of the heavens, which had been unknown to the ancients; and examin¬ ing Jupiter, he found him attended by four ftars, which, at certain periods, performed revolutions round him. This difeovery he made in January 1610, new ftyle; and continuing his obfervations the whole of February following, he publifhed, in the beginning of March, ait account of all his difeoveries, in his Nuncius Sidertus, printed at Venice. The extraordinary difeoveries contained in the Nun¬ cius Sidereus, which was immediately reprinted both in Germany and France, were the caufeof much debate among the philofophers of that time ; many of whom could not give any credit to Galileo-'s account, while others endeavoured to decry his difeoveries as nothing more than mere illufions. In the beginning of July, 1610, Galieo being ftill at Padua, and getting an imperfebt view of Saturn’s ring, imagined that that planet confifted of three parts ; and therefore, in the account which he gave of this difeovery to his friends, he calls it planetarn ter- geminam. Whilft he was ftill at Padua, he obferved fome fpots on the face of the fun : but he did not choofe, at that time, to publifti his difeovery ; partly for fear of incur¬ ring more of the hatred of many obftinate Peripatetics; and partly in order to make more exabf obfervations on this remarkable phenomenon, as well as to form fome conjecture concerning the probable caufe of it. He therefore contented himfelf with communicating his ob¬ fervations to fome of his friends at Padua and Venice, B b 2 among 196 Hiftory. 73 Account of his te- lefcepes. 74 l he ratio¬ nale of the inftrument firft difco- vered by Kepler. General reafon of the effects of tele¬ scopes. OPT among whom we find the name of Father Paul. This delay, however, was the caufe of this difcovery being contefted with him by the famous Scheiner, who like- wife made the fame obfervation in Odtober 1611, and we fuppofe had anticipated Galileo in the publication of it. In November following Galileo was fatisfied, that, from the September preceding, Venus had been conti¬ nually increafing in bulk, and that file changed her pha- fes like the moon. About the end of March 1611, he went to Rome, where he gratified the cardinals, and all the principal nobility, with a view of the new wonders which he had difcovered in the heavens. Twenty-nine years Galileo enjoyed the ufe of his te- lefcope, continually enriching aftronomy with his obfer- vations : but by too clofe an application to that inftru¬ ment, and the detriment he received from the nofturnal air, his eyes grew gradually weaker, till in 1639 he be¬ came totally blind j a calamity which, however, nei¬ ther broke his fpirits, nor interrupted the courfe of his ftudies. The firft telefcope that Galileo conftrufted magni¬ fied only three times 5 but prefently after, he made another which magnified 18 times } and afterwards with great trouble and expence, he conftrudted one that magnified 33 times j and with this it was that he difcovered the fatellites of Jupiter and the fpots of the fun. The honour of explaining the rationale of the tele¬ fcope is due to the celebrated Kepler. He made feve- ral difcoveries relating to the nature of vifion ; and not only explained the theory of the telefcope which he found in ufe, but alfo pointed out methods of conftrutt- ing others of fuperior powers and more commodious ap¬ plication. It was Kepler who firft gave a clear explication of the effedfts of lenfes, in converging and diverging the rays of a pencil of light. He fhorved, that a plano-convex lens makes rays that were parallel to its axis, to meet at the diftance of the diameter of the fphere of convexity 5 but that if both fides of the lens be equally convex, the rays will have their focus at the diftance of the radius of the circle, correfponding to that degree of convexity. He did not, however, inveftigate any rule for the foci of lenfes unequally convex. He only fays, in general, that they will fall fomewhere in the middle, between the foci belonging to the two different degrees of convexity. We owe this inveftigation to Gavalieri, who laid down the following rule : As the fum of both the diameters is to one of them, fo is the other to the diftance of the focus. The principal effecls of telefcopes depend upon thefe fimple principles, viz. That objefts appear larger in proportion to the angles which they fubtcnd at the eye •, and the effeft is the fame whether the pencils of rays, by which objefts are vifible to us, come dire&ly from the objedts themfelves, or from any place nearer to the eye, where they may have been converged fo as to form an image of the objedt 5 becaufe they iffue again from thofe points where there is no real fubftance, in certain dire&ions, in the fame manner as they did from the correfponding points in the objedls themfelves. In fadl, therefore, all that is effcdted by a telefcope is, firft, to make fuch an image of a diftant obiedl, by means of a lens or mirror j and then to give the eye 3 I c s. fome afliftance for viewing that image as near as pof- Hiftory. fible : fo that the angle which it ftiall fubtend at the » J eye, may be very large, compared with the angle which the objedl itfelf would fubtend in the fame fituation. Thy, is done by means of an eye-glafs, which fo re- fradb the pencils of rays, that they may afterwards be brought to their feveral foci by the humours of the eye. But if the eye was fo formed as to be able to fee the- image with futficient diftindtnefs at the fame diftance without any eye-glafs, it would appear to him as much magnified as it does to another perfon who makes ufe of a glafs for that purpofe, though he would not in all cafes have fo large a field in view. If, inftead of an eye-glafs, an object: be looked at througli a fmall hole in a thin plate or piece of paper, held clofe to the eye, it may be viewed very near to the eye, and, at the fame diftance, the apparent magnitude of the objedh will be the fame in both cafes. For if the hole be fo fmall as to admit but a fingle ray from every point of the objedl, thefe rays will fall upon the retina in as many other points, and make a diftindt image. They are only pencils of rays, which have a fenfible bafe, as the breadth of the pupil, that are capable, by their fpreading on the retina, of producing an indif- tindl image. As very few rays, however, can be admitted through a fmall hole, there will feldom be light fufficient to view any objeft to advantage in this manner. If no image be formed by the foci of the pencils without the eye, yet if, by the help of a concave eye- glafs, the pencils of rays fliall enter the pupil, juft as they would have done from any place without the eye, the vifual angle will be the fame as if an image had adfually been formed in that place. Objects will not appear inverted through this telefcope, becaufe the pen¬ cils which form the images of them, only crofs one an¬ other once, viz. at the objedl glafs, as in natural vifion they do in the pupil of the eye. ^ Such is the telefeope that was firft difcovered and Galilean ufed by philofophers. The great inconvenience attend-telefeope ing it is, that the field of view is exceedingly fmall. For fince the pencils of rays enter the eye very much ftrufticm diverging from one another, but few of them can be than others, intercepted by the pupil. This inconvenience increafes with the magnifying power of the teiefcope •, fo that it is a matter of furprife how, with fuch an inftrument, Galileo and others could have made fuch difcoveries. No other telefcope, however, than this, was fo much as thought of for many years after the difcovery. Defcar- tes, who wrote 30 years after, mentions no others as ac¬ tually conftrudled. *7 It is to the celebrated Kepler that we are indebtedTelefcopej for the, conftruction of what we now call the ajlronotm- nnpioved cal telefcope. The rationale of this inftrument is ex-k>’er* plained, and the advantages of it are clearly pointed out, by this philofopher, in his Catoptrics ; but, what is very furprifing, he never adfually reduced his theory into pradlice. Montucla conjedtures, that the reafon why he did not make trial of this new conftrudfion was, his not being aware of the great increafe of the field of view 5 fo that being engaged in other purfuits, he might not think it of much confequence to take any pains about the conftrudlion of an inftrument, which could do little more than anfwer the fame purpofe with thofe which he already poffeffed. He muft alfo have forefeen, that the length OPTICS. Hiftory. length of this telefcope mull have been greater in pro- ‘ v ’ portion to its magnifying power, fo that it might ap¬ pear to him to be upon the whole not quite fo good a 78 conllruftion as the former. His method f lie frit perfon who aftually made an inllrument of ^raclice'b KcPler’s conflrudion was Father Scheiner, who has Stlieiner. Y S'*''011 a defcription of it in his Rofa Urjina, publifhed in 1630. If, fays he, you infert two limilar lenfes in a tube, and place your eye at a convenient diftance, you will fee all terreftrial objects, inverted, indeed, but magnified, and very diltincit, with a confiderable extent of view. He afterwards fubjoins an account of a tele¬ fcope. of a different conftruftion, with two convex eye- glalfes, which again reverfes the images, and makes them appear in their natural pofition. This difpofition of the lenfes had alfo been pointed out by Kepler, but had not been reduced to praftice. This conllrudion, however, anfwered the end very imperfeftly 5 and Fa¬ ther Kheita prefently after difcovered a better conftruc- tion, ufing three eye-glafles inftead of two. The only difference between the Galilean and the aftronomical telefcope is, that the pencils by which the extremities of any object are feen in this cafe, enter the eye diverging; whereas, in the other they enter it con¬ verging; but if the fphere of concavity in the eye-glafs of the Galilean telefcope be equal to the fphere of con¬ vexity in the eye glafs of another telefcope, their mag¬ nifying power will be the fame. The concave eye-glafs, however, being placed between the obje£t-glafs and its focus, the Galilean telefcope will be Ihorter than the other, by twice the focal length of the eye-glafs. Con- fcquently, if the length of the telefcopes be the fame, ^ the Galilean will have the greater magnifying power. Huygens Huygens was particularly eminent for his lyllematic improves knowledge of optics, and is the author of the chief im- fcojefof Provements which have been made on all the dioptrical Scheiner 'lnftrurnents till the difcovery of the achromatic telefcope. and Rheita. He was well acquainted with the theory of aberration arifing from the fpherical figure of the glaffes, and has ffiown feveral ingenious methods of diminilhing them by proper conltruttions of the eye-pieces. Fie firlt pointed out the advantages of two eye-glafles in the aftronomical telefcope and double microfeope, and gave rules for this conftrudtion, which both enlarges the field and (hortens the inftrument. Mr Dollond adapted his conftrudion to the terreftrial telefcope of De Kheita ; and his five eye-glaflfes are nothing but the Huygenian eye-piece doubled. This conftru£tion has been too haftily given up by the artifts of the prefent day for another, go alfo of Mr Dollond’s, of four glafles. Binocular f he fame Father Rheita, to whom we are indebted telefcope. for the conftru£lion of a telefcope for land objedls, in¬ vented a binocular telefcope, which Father Cherubin, of Orleans, afterwards endeavoured to bring into ufe. It confifts of two telefcopes faftened together, pointed to the fame objecft. When this inftrument is well fixed, the object appears larger, and nearer to the eye, when it is feen through both the telefcopes, than through one of them only, though they have the very fame magnify¬ ing power. But this is only an illufion, occafioned by the ftronger impreflion made upon the eye, by two equal images, equally illuminated. This advantage, however, is counterbalanced by the inconvenience attending the ufe of it. 'Ihe firft who diftinguilhed themfelves in grinding telefcopic glafles were two Italians, Euftachio Divini Hiftory. at Rome, and Campani at Bologna, whofe fame was ‘ v~~' ’ much fuperior to that of Divini, or that of any other T perfon oi his time ; though Divini himfelf pretended, 0fecampani that, in all the trials that were made with their glaffes, and Divini. his, of a greater focal length, performed better than thofe of Campani, and that his rival was not willing to try them with equal eye-glafles. It is generally fuppo- fed, however, that Campani really excelled Divini, both in the goodnefs and the focal length of his objedt- glafles. It was with telefcopes made by Campani that Caflini difcovered the neareft fatellites of Saturn. They were made by the exprefs order of Louis XIV. and were of 86, 100, and 136 Paris feet in focal length. Campani fold his lenfes for a great price, and took every poflible method to keep his art of making them fecret. His laboratory was inacceflible, till alter his death ; when it was purchafed by Pope JBenedidl XIV. who prefented it to the academy called the Injlitute, eftablilhed in that city; and by the account which M„ Fougeroux has given of what he could difcover from it, we learn, that (except a machine, which M. Campani conftrudted, to work the bafons on which he ground his glafles) the goodnefs of his lenfes depended upon the clearnefs of his glafs, his Venetian tripoli, the paper with which he polilhed them, and his great Ikill and addrefs as a Avorkman. It was alfo the general opi¬ nion that he orved much of his reputation to the fecrecy. and air of myftery which he affe&ed; and that he made a great number of object-glafles which he reje&ed, Ihow- ing only thofe that Avere very good. He made feAV lenfes of a very great focal diftance; and having the misfortune to break one of 141 feet in tAvo pieces, he took incredible pains to join the tAvo parts together, which he did at length fo effedlually, that it Avas ufed as if it had been entire ; but it is not probable that he Avould have taken fo much pains about it, if, as he pre¬ tended, he could very eafily have made another as good. Sir Paul Neille, Dr Hooke fays, made telefcopes of 36 feet, pretty good, and one of 50, but not of pro¬ portional goodnefs. AfterAvards Mr Reive, and then Mr Cox, Avho were the moll celebrated in England as grinders of optic glaffes, made fome good inftruments of 50 and 60 feet focal length, and Mr Cox made one of 1°°. g Thefe, and all other telefcopes, Avere far exceeded by ExtraoHv an obje£t-glafs of 600 feet focus made by M. Auzout; nary object but he Avas never able to manage it. Hartfocker is even glafs made faid to have made fome of a ftill greater focal length • br M‘ Au“ but this ingenious mechanic, finding it impoffible to make ufe of objed-glafles the focal diftance of Avhich Avas much lefs than this, when they Avere enclofed in a tube, contrived a method of ufing them Avithout a tube, by fixing them at the top of a tree, a high wall, or the roof of a houfe. Mr Huygens, who Avas alfo an excellent mechanic, Telefcopes maoe confiderable improvements on tins contrivance of ufed with— Hartfocker’s. He placed the objed-glafs at the top of0jL tubes* a long pole, having previoufly enclofed it in a fhort tube Avbich Avas made to turn in all diredions by means of a bail and focket. 1 he axis of this tube he could com¬ mand AAith a fine fifteen firing, lo as to bring it into a line with the axis of another Ihort tube Avhich he held in his uand, and Avhich contained the eye-glafs. In this method he could make ufe of objed-glaifes of the greatell Plate 198 OPT Hiitory. grvateft magnifying power, at whatever altitude his ob- jeft ayas, and even in the zenitli, provided his pole was as long as his telefcope j and to adapt it to the view of objctts of different altitudes, he had a contrivance, by which he could raife or deprels at pleafure, a ftage that fupported his objedl-glafs. M. de la Hire made fome improvements in this method of managing the objeft-glafs, by fixing it in the centre of a board, and not in a tube 5 but as it is not probable that this method will ever be made ufe of, fince the difeovery of both reflecting and achromatic telefcopes, which are now brought to great perfeflion, and have even micro¬ meters adapted to them, we fhall not deferibe the ap¬ paratus minutely, but (hall only give a drawing of M. Huygen’s pole, with a fhort explanation. In fig. 1. « reprefents a pulley, by the help of which a ftage c, cl% e, f, (that fupports the objeft-glafs k, and the apparatus cc—vn belonging to it), may be railed higher or lower at plea- lo ' fure, the whole being counterpoifed by the weight k, .fattened to a ftring g. n, is a weight, by- means of which the centre of gravity of the apparatus belonging to the objeft-glais is kept in the ball and locket, fo that it may be eafily managed by the ftring /u, and its axis brought into a line with the eye-glafs at 0. When it was very dark, M. Huygens was obliged to make his objedt-glafs vifible by a lantern, 1/, lo conftrutfted as to $4 throw up to it the rays of light in a parallel dire61ion. Of the a- Before leaving this fubjeift, it mutt; be obferved, refra^n°f t'iat Auzout, in a paper delivered to the Royal telefcopes. Society, obferved, that the apertures which the objedd- glaffes of refradting telefcopes can bear with diftindl- nefs, are in the fubduplicate ratio of their lengths ; and upon this fuppofition he drew up a table of the aper¬ tures of objedt-glaffes of a great variety of focal lengths, from 4 inches to 400 feet. Upon this occafion, how¬ ever, Dr Hooke obferved, that the fame glafs will bear a greater or lefs aperture, according to the lefs or greater light, of the objedl. But all thefe improvements were diminiftied in value by the difeovery of the rt-fieSiing telefcope. For a refrac¬ ting telefcope, even of 1000 feet focus, fuppofing it poftible to be made ufe of, could not be made to mag¬ nify with diftindlnefs more than IOOO times •, whereas a reflecting telefcope, not exceeding 9 or 10 feet will g magnify 1 200 times, Hiftory of “ It mutt be acknowledged, fays Dr Smith, that Mr the refledt- James Gregory of Aberdeen was the firft inventor of the ing tele- refledling telefcope ; but his conftrudlioh is quite dif¬ ferent from Sir Ifaac Newton’s, and not nearly fo ad¬ vantageous.” According to Dr Pringle, Merfennus was the man who entertained the fi ft thought of a refle&or. He cer¬ tainly propofed a telefcope with fpecula to the celebrated Defcartes many years before Gregory’s invention, though indeed in a manner fo very unfatisfadlory, that Defcar¬ tes was fo far from approving the propofal, that he endeavoured to convince Merfennus of its fallacy. Dr Smith, it appears, had never perufed the two letters of Defcartes to Merfennus which relate to that fubje£f. Gregory, a young man of uncommon genius, was led to the invention, in trving to correct two imperfections of the common telefcope : the firft was its too great length, which made it lefs manageable ; the fecund, the jncorretnefs of the image. Mathematicians had de monftrated, that a pencil of rays could not be colle&ed 4 fcop«. ICS. ‘in a Angle point by a fpherical lens ; and alfo, that the Hifterr. image tranfmitted by fuch a lens would be in fome de- gree incurvated. Thefe inconveniences he believed would be obviated by fubftituting for the obje£l-glafs a metallic fpeculum, of a parabolic figure, to receive the incident rays, and to refleH them towards a fmall fpecu¬ lum of the fame metal ; this again was to return the image to an eye-glafs placed behind the great fpeculum, which for that purpofe was to be perforated in its centre. This conftru£Hon he publilhed in 1663, in his Optica Pramcta. But as Gregory, by his own account, was endowed with no mechanical dexterity, nor could find any workman capable of conttru£ting his inftrument, he was obliged to give up the purfuit: and probably, had not fome new difeoveries been made in light and colours, a reflefting telefcope would never more have been thought of. At an early period of life, Newton had applied him- felf to the improvement of the telefcope; but imagin¬ ing that Gregory’s fpecula were neither very neceffary, nor likely to be executed, he began with profecuting the views of Defcartes, who aimed at making a more perfeft image of an objeft, by grinding lenfes, not to the figure of a fphere, but to that of one of the conic fedlions. Whillt he was thus employed, three years after Gregory’s publication, he happened to examine the colours, formed by a prifm, and having by means of that fimple inftrument difeovered the different refrangibility of the rays of light, he then perceived that the errors of telefcopes ariftng from that caufe alone, were fome hundred times greater than thofe which were occafioned by the fpherical figure of lenfes. This cir- cumftance forced, as it were, Newton to fall into Gre¬ gory’s track, and to turn his thoughts to refie£lors. “ The different refrangibility of the rays of light (fays he in a letter to Mr Oldenburg, fecretary to the Royal Society, dated Feb. 1672) made me take reflexions into confideration *, and finding them regular, fo that the angle of refleftion of all forts of rays vras equal to the angle of incidence, I underflood that by their me- ; diation optic inftruments might be brought to any de¬ gree of perfeXion imaginable, providing a refleXing fubftance could be found which would polifli as finely as glafs, and refleX as much light as glafs tranfmits, and the art of communicating to it a parabolical figure he alfo obtained. Amidft thefe thoughts 1 was forced from Cambridge by the intervening plague, and it was more than two years before I proceeded further.” It was towards the end of 1668, or in the beginning of the following year, when Newton being obliged to have reeourfe to refleXors, and not relying on any arti¬ ficer for making his fpecula, fet about the work himfelf, and early in the year 1672 completed two fmall refleX¬ ing telefcopes. In thefe he ground the great fpeculunt into the concave portion of a fphere $ not but that he approved of the parabolic form propofed by Gregory, though he- found himfelf unable to accomplilh it. In the letter that accompanied one of thefe inftruments which he prefented to the Society, he writes, “ that though he then defpaired of performing that work (to wit, the parabolic figure of the great fpeculum) by geome¬ trical rules, yet he doubted not but that the thing might in fome meafure be accoropliftied by mechanical devices.” Not lels did the difficulty appear to find a metallic fubftance OPT Hiftory. fubftance that would be of a proper hardnefs, have the ' ‘ feweft pores, and receive the fmootheft polifh j a diffi¬ culty which he deemed almoft unffirmountable, when he conlidered, that every irregularity in a ref!e£Hng fvir- face would make the rays of light ftray five or fix times more out'of their due courfe, than fimilar irregularities in a refrafting one. In another letter, written foon af¬ ter, he informs the fecretary,-^ “ that he was very fenfi- ble that metal reflefts lefs light than glafs tranfmits; but as he had found fome metallic fubflances more Itrongly refle£tive than others, to polifh better, and to be freer from tarnifhing than others, fo he hoped that there might in time be found out fome fubftances much freer from thefe inconveniencies than any yet known.” New¬ ton therefore laboured till he found a com poll tion that anfwered in fome degree, and left it to tllofe who ffiould come after him to find a better. Huygens, one of the grcatefi: geniufes of the age, and a diitinguiihed improver of the refracting telefcope, no fooner was in¬ formed by Mr Oldenburg of the difcovery, than he wrote in anfwer, “ that it was an admirable telefcope 5 and that Mr Newton had w’ell confidered the advantage which a concave fpeculum had over convex glaffes in collecting the parallel rays, which, according to his own calculation, was very great: Hence that Mr Newton could give a far greater aperture to that fpeculum than to an objeCt glafs of the fame focal length, and confequently produce a much greater magnifying power than by an ordinary telefcope: Befides, that by the re- fieCtor he avoided an inconvenience infeparable from objeCt glaffes, which was the obliquity of both their fur- faces, which vitiated the refraCtion of the rays that pafs towards the fide of the glafs : Again, That by the mere reflection of the metalline fpeculum there were not fo many rays loft as in glaffes, which reflected a confider- able quantity by each of their furfaces, and befides in¬ tercepted many of them by the obfeurity of their fub- ftance : That the main bufinefs would be to find a fub- ftance for this fpeculum that would bear as good a po¬ lifh as glafs. Laftly, He believed that Mr NewTon had not omitted to confider the advantage which a para¬ bolic fpeculum would have over a fphcrical one in this conftruCtion; but had defpaired, as he himfelf had done, of working other furfaces than fpherical ones with ex- aClnefs.” Huygens was not fatisfied with thus expref- fing to the foeiety his high approbation of the inven¬ tion } but drew up a favourable account of the new te¬ lefcope, which he publifhed in the Journal des Spa-vans for 1672, by which channel it was foon known over Europe. Excepting an unfuccefsful attempt which the fociety made, by employing an artificer to imitate the Newto¬ nian conftruClion, but upon a larger fcale, and a dif- guifed Gregorian telefcope, fet up by Caffegrain abroad as a rival to Newton’s, no refleClor wTas heard of for nearly half a century after. But when that period was elapfed, a refleCHng telefcope of the Newtonian form was at laft produced bv Mr Hadley, the inventor of the refleCling quadrant. The two telefcopes which Newton had made were but fix inches long *, they were held in the hand for viewing objeCts, and in power were com¬ pared to a fix feet refra&or ; whereas Hadley’s was about five feet long, was provided with a well-contrived apparatus for managing it, and equalled in performance the famous aerial telefcope of Huygens of 123 feet in I c s. 199 length. Excepting the manner of making the fpecula, Hiftory. we have, in the Philofophical Tranfa&ions of 1723, a " '»-r™ complete defeription, with a figure of this telefcope, to¬ gether with that of the machine for moving it 3 but, by a ftrange omiffion, Newton’s name is not once mention¬ ed in that paper, fo that any perfon not acquainted with the hiftory of the invention, and reading that ac¬ count only, might be apt to conclude that Hadley had been the foie inventor. The fame celebrated artift, after finifhing two tele¬ fcopes of the Newtonian conftrudtion, accomplilhed a third of the Gregorian form 3 but, it would feem, lefs fuccefsfully. Mr Hadley fpared no pains to inftruct Mr Molyneux and the Reverend Dr Bradley 3 and when thofe gentlemen had made a fufficient proficiency in the art, being defirous that thefe telelcopes ftiould become more public, they liberally communicated to fome of the principal inftrument-makers of London the know¬ ledge they had acquired from him. Mr James Short, as early as the year 1734, had fignalized himfelf at Edinburgh by the excellence of his telefcopes. Mr Maclaurin wrote that year to Dr Jurin, “ that Mr Short, who had begun with making glafs fpecula, was then applying himfelf to improve the metallic 3 and that by taking care of the figure, he was enabled to give them larger apertures that others had done 3 and that upon the whole they furpaffed in perfection all that he had feen of other workmen.” He added, “ that Mr Short’s telefcopes wTere all of the Gregorian conftruftion 3 and that he had much im¬ proved that excellent invention.” This character of excellence Mr Short maintained to the laft 3 and v’ith the more facility, as he was well acquainted with the theory of optics. It was fuppofed that he had fallen upon a method of giving the parabolic figure to his great fpeculum 3 a point of perfection that Gregory and Newton had defpaired of attaining 3 and that Had¬ ley had never, as far as wTe know, attempted. Mr Short indeed affirmed, that he had acquired that faculty, but never would tell by what peculiar means he effeCled it; fo that the fecret of working that configuration, what¬ ever it was, died with that ingenious artift. Mr Mudge, however, has lately realized the expeClation of Sir Ifaac Newton, who, above 100 years ago, preiaged that the public would one day poffefs a parabolic fpeculum, not. aecompliihed by mathematical rules, but by mechanical devices. This Vas a defideratumy but it was not the only want fupplied by this gentleman : he has taught us likewife a better compofition of metals for the fpecu¬ la, how to grind them better, and how to give them a finer polifh 3 and this laft part (namely, the polith), he remarks, was the moft difficult and effential of the whole operation. “ In a word (fays Sir John Pringle), I am of opinion, there is no optician in this great city (which hath been fo long and fo juftly renowned for ingenious and dexterous makers of every kind of ma¬ thematical inftruments) fo partial to his own abilities as not to acknowledge, that Mr Mudge has opened to them all fome new and important lights, and has greatly improved the art of making reflefting tele- M c IVIf Ld- COP5S* , j j • . , i ttj j j waids’sim- 1 he late reverend and ingenious John Edwards de-provements voted much of his time to the improvement of re-of the re¬ flecting telefcopes, and brought them to fuch per- fieClmg te- fecTion,lefcoPe- 200 Hiftory OPTICS. S? Herfchel’ improve¬ ments. S8 Account Mr Dol- lond’s im prove- ments. • fe£Uon, that Dr Malkelyne, the aftronomer royal, found telefeopes conftru£ted by him to furpafs in brightnefs, and other refpefts, thofe of the fame fize made by the beft artifts in London. The chief ex¬ cellence of his telefcopes arifes from the compofition, which, from various trials on metals and femimetals, he difcovered for the fpecula, and from the true pa¬ rabolic figure, which, by long pradlice, he had found a method of giving them, preferable to any that was known before him. His direflions for the compofition of fpecula, and for calling, grinding, and polilhing them, were publilhed, by order of the commiflloners of longitude, at the end of the Nautical Almanack for the year 1787. To the fame almanack is alfo an¬ nexed his account of the caufe and cure of the tremors which particularly aflFedl refle£ling telefcopes more than refradling ones, together with remarks on thefe tremors by Dr Malkelyne. s But in conltrufting refiefling telefcopes of extra¬ ordinary magnifying powers, Dr Herfchel has difplay- ed Ikill and ingenuity furpafling all his predeceffors in this department of mechanics. He has made them from 7, 10, 20, to even 40 feet in length j and with inllruments of thefe dimenfions he is now employed in making difcoveries in aftronomy. Of the conllruftion, magnifying powers, and the curious collection of ma¬ chinery by which his 40 feet telefcope is fupported and moved from one part of the heavens to another, accounts will be given under the word Telescope. The greatelt improvement in refraRing telefcopes hitherto made public is that of Mr Dollond, of which an account has already been given in a preceding fec- tion, in which his difcoveries in the fcience of Optics were explained. But, befides the obligation -we are under to him for correcting the aberration of the rays of light in the focus of objeCt-glafies, he made another confiderable improvement in telefcopes, viz. by correct¬ ing, in a great meafure, both this kind of aberration, and alfo that which arifes from the fpherical form of lenfes, by an expedient of a very different nature, viz. increafing the number of eye glaffes. 0f If any perfon, fays he, would have the vifual angle of a telefcope to contain 20 degrees, the extreme pen- - cils of the field mull be bent or refraCled in an angle of 10 degrees 5 which, if it be performed by one eye- glafs, will caufe an aberration from the figure, in pro¬ portion to the cube of that angle ; but if two glaffes be fo proportioned and fituated, as that the refraClion may be equally divided between them, they -will each of them produce a refraClion equal to half the required angle ; and therefore, the aberration being proportion¬ al to the cube of half the angle taken twice over, will be but a fourth part of that whicli is in propor¬ tion to the cube of the whole angle j becaufe twice the cube of one is but of the cube of 2 •, fo the aber¬ ration from the figure, where two eye-glaffes are right¬ ly proportioned, is but a fourth of what it mull un¬ avoidably be, -where the whole is performed by a fingle eye-glafs. By the fame way of reafoning, when the re¬ fraClion is divided between three glaffes, the aberra¬ tion will be found to be but the ninth part of what would be produced from a fingle glafs} becaufe three times the cube of 1 is but one-ninth of the cube of 3. Whence it appears, that by increafing the number of -ye-glaffcs, the indiltinClnefs which is obferved near the borders of the field of a telefcope may be very much di- Hiftory. minilhed. v iuJ The method of correCling the errors arifing from the different refrangibility of light is of a different con- fideration from the former. For, whereas the errors from the figure can only be diminilhed in a certain proportion according to the number of glaffes, in this they may be entirely corrected by the addition of only one glafs. Alfo in the day-telefcope, where no more than two eye-glaffes are abfolutely neceffary for ereCl- ing the objeCl, we find, that by the addition of a third, rightly fituated, the colours, which -would otherwife make the image confufed, are entirely removed. This, however, is to be underitood with fome limitation : for though the different colours into which the extreme pencils muff neceffarily be divided by the edges of the eye-glaffes, may in this manner be brought to the eye in a direction parallel to each other, fo as to be made to converge to a point on the retina 5 yet, if the glaffes ex¬ ceed a certain length, the colours may be fpread too wide to be capable of being admitted through the pu¬ pil or aperture of the eye ; which is the reafon, that in long telefcopcs, conftruCled in the common manner, with three eye-glaffes, the field is always very much con- traCled. •« Thefe confiderations firft fet Mr Dollond on contri¬ ving how to enlarge the field, by increafing the num¬ ber of eye-glaffes without affeCting the diftinCtnefs or brightnefs of the image ; and though others had been about the fame work before, yet, obferving that fome five-glafs telefcopes which were then made would admit of farther improvement, he endeavoured to conllruCl one with the fame number of glaffes in a better manner ; which fo far anfwered his expectations, as to be allowed by the bell judges to be a confiderable improvement on the former. Encouraged by this fuccefs, he refolved to try if he could not make fome farther enlargement of the field, by the addition of another glafs, and by placing and proportioning the glaffes in fuch a manner as to correCt the aberrations as much as poffible, without injuring the diftinClnefs 5 and at lafl he obtained as large a field as is convenient or neceffary, and that even in the longeft telefcopes that can be made. Thefe telefcopes with fix glaffes having been well received, and fome of them being carried into foreign countries, it feemed a proper time to the author to fettle the date of his invention ; on which account he drew up a letter, which he addrefied to Mr Short, and which was read at the Royal Society, March 1. 1753. To Mr Short we are indebted for the excellent eon-^ • . trivance ot an equatorial telelcope, or, as lie likewile teiefCOpe> called it, a portable obfervatory ; for with it pretty ac-or portable curate obfervations may be made with very little trouble, °hierva- by thofe who have no building adapted to the purpofe.tor^' The inftrument confifts of a piece of machinery, by which a telefcope mounted upon it may be dire£led to any degree of right afeenfion or declination, fo that the place of any of the heavenly bodies being known, they may be found without any trouble, even in the day-time. As it is made to turn parallel to the equator, any object is eafily kept in view, or recovered, without moving the eye from its fituation. By this inilrument moll of the ftars of the firft and fecond magnitude have been feen even at mid-day, when the fun was ftiining bright; as alfo I-Mcry. ftars in the day-time. 9i M. Epi- tms’s pro- pofal for alfo Mercury, Venus, and Jupiter. Saturn and Mars are not fo eafy to be feen, on account of the faintnefs of their light, except when the fun is but a few hours above the horizon. This particular effed depends upon the telefcope excluding almolt all the light, except what comes from the objed itfelf, and which might other- wife efface the impreflion made by its weaker light upon tlie eye. Any telefcope of the fame magnifying power would have the fame effed, could we be fure of pointino- it right. Mr Ramfden invented a portable or equatorial telefcope, which may perhaps fuperiede the ufe of Mr po Short’s How to ob- In order to fee the fixed ftars In the day-time, it is ierve the neceflary to exclude the extraneous light as much as poflible. For this reafon the greater the magnifying power of any telefcope is, the more eafily a fixed ftar will be diftinguithed in the day-time ■ the light of the ftar remaining the fame in all magnifying powers of the lame telefcope, but the ground upon which it is feen becoming darker by increafing the magnifying power j and the vifibility of a ftar depends very much upon the difference between its own light and that of the ground upon which it is obferved. A fixed ftar will be very nearly equally vifible with telefcopes of very dif¬ ferent apertures, provided the magnifying power remains the fame. M. -/Epinus propofes to bend the tubes of long te¬ lefcopes at right angles, fixing a plane mirror in the b nli according to Borellus, ’ 've are indebted for them to the fame author, at leaft to Zacharias Janfen, in conjunftion with his fon. The Janfen*, however, have not always enjoyed, undifturbed, that fhare of reputation to which they feem to be entitled, with refpeft either to the telefcope or the microfcope. The difeovery of the latter, in par¬ ticular, has generally been confidered as more uncer¬ tain than that of the former. All that many writers fay we can depend upon is, that microfcopes were firft ufed in Germany about the year 1621. Others fay Positively, that this inftrument was the contrivance of Cornelius Drebell, a man of ingenuity, who alfo invent¬ ed the thermometer. According to Borellus, Zacharias Janfen and his fon prefented the firft microfcopes they had conftrufted to Prince Maurice, and Albert archduke of Auftria. Wil¬ liam Borell, who gives this account in a letter to his brother eter, fays, that when he was ambaffador in England, in 1619, Cornelius Drebell, with whom he was intimately ac- 93 quainted, fliowed him a microfcope, which he faid was the ^ icrofcope fame that the archduke had given him, and had been made by Janlen himfelf. This inftrument was not fo fiiort as they are generally made at prefent, but was fix feet lono- confifting of a tube of gilt copper, an inch in diameter* lupported by three brafs pillars in the fliape of dolphins, on a bate of ebony, on which the fmall objeds were placed. Vox. XV. Part I. 1 OPTICS. 201 This microfcope was evidently a compound one, or Hiftory. rather fomething betwixt a telefcope and a microfcope; fo that it is pofiible that fingle microfcopes might have been known, and in ufe, feme time before : but perhaps nobody thought of giving that name to fingle lenfes; though, from the firft ufe of lenfes, they could not but have been ufed for the purpofe of magnifyino- fmall objects. In this fenfe we have feen, that even the ancients were in pofie/fion of microfcopes ; and it appears from Jamblicus and Plutarch, quoted by Dr Rogers, that they gave filch inftruments as they ufed foi this purpofe the name of dioptra. At what time lenfes were made fo fmall as we now generally ufe them for magnifying in fingle microfcopes, we have not found. But as this mult neceffarily have been done gradually, the only proper objed of inquiry is the invention of the double microfcope; and this is clearly given, by the evidence of Borellus above mentioned, to Z. Janfen, or his fon. i he invention of compound microfcopes is claimed by the fame Fontana who arrogated to himfelf the dif- covery of telefcopes; and though he did not publifh any account of this invention till the year 1646 (not- withftanding he pretended to have made the difeovery in 1618), Montucla, from not attending perhaps to the teftimony of Borellus, is willing to allow his claim, as he thought there was no other perfon who feemed to have any better title to it. Euftachio Divini made microfcopes with two com- -r , tv4-- • mon objeft-glaffes, and two plano-convex eye-glaffes ^ joined together on their convex fides fo as to meet in a point. The tube in which they were inclofed was very large, and the eye-glaffes almoft as broad as the palm of a man’s hand. Mr Oldenburg, fecretary to the Royal Society, received an account of this inftrument fiom Rome, and read it at one of their meetinp-s A urrnfl- ^ * | pnfen. Auguft 6. 1668. It was about this time that Hartfccker improved By H*rt- iingle microfcopes, by ufing fmall globules of glafs looker, made by melting them in the flame of a candle, in- Itead Oi the lenfes which had before been made ufe of for that purpofe. By this means he firft dilcovered the ammalcula in femme mufculino, which gave xife to a new fyftem of generation. A microfcope of this kind confiding of a globule of ^ of an inch in diameter’ M. Huygens demonftrated to magnify 100 times ; and fmee it is eafy to make them of left than half a line in diameter, they may be made to magnify 300 times. But no man diftinguiflied himfelf fo much by micro-By Leeu fcopical difeoveries as the famous M. Leeuwenhoek wenhoek. though he uled only fingle lenfes with fliort foci, pre¬ ferring diftinanefs of vifion to a large magnifying power. M. Leeuwenhoek’s microfcopes were all fingle ones* each of them confifting of a fmall double convex glafs’ fet in a focket between two filver plates rivetted tooe- ther, and pierced with a fmall hole; and the objeft was fixed on the point of a needle, which could be placed at any diftance from the lens. If the objeas -were foHd, he fattened them with glue; and if they u ere fluid, or required to be fpread upon 'dais, he -placed them on a fmall piece of Mufcovy talc, or thin •glafs ; which he afterwards glued to his needle. He had, however, a different apparatus for viewing the circulation of the blood, which he could attach to the fame microfcopes. Cc M. 97 Wilfon’s niieroicope 9S Adams’s method of making glo. bules for large mag¬ nifiers. OPT M. Leeuwenhoek bequeathed the greatell part of his microfcopes to the Royal Society. They were placed in a fmall Indian cabinet in the drawers of which were 13 little boxes, each of which contained twro mi- crofcopes, neatly fitted up in filver. The glafs of all thefe lenfes is exceedingly clear, but none of them magnifies fo much as thofe globules which are frequently ufed in other microfcopes. Air Folkes, who examined them, thought that they {howed objefts with much greater diftindlnefs, a circumftance which AI. Leeuwenhoek principally valued. His difeo- veries, however, are to be aferibed not fo much to the goodnefs of his glaffes, as to his great experience in ufing them. Air Baker, who alfo examined thefe microfcopes, and reported concerning them to the Royal Society, found that the greatelt magnifier enlarged the diameter of an object about 160 times, but that all the reft fell much ftiort of that power. He therefore concluded that AI. Leeuwenhoek muft have had other microfcopes of a much greater magnifying power for many of his difeoveries. It appears from AI. Leeuwenhoek’s writings, that he was not unacquainted with the method of viewing opaque objects by means of a fmall concave reflecting mirror, which was afterwards improved by AI. Lie- berkhun. For, after deferibing his apparatus for view¬ ing eels in glafs tubes, he adds, that he had an inftru- ment to which he ferewed a microfcope fet in brafs, upon which microfcope he faftened a little difii of brafs, probably that his eye might be thereby affifted to fee objects better j for he fays he had filed the brafs which w'as round his microfcope as bright as he could, that the light, while he was viewing objects, might be refle&ed from it as much as poffible. This micro¬ fcope, with its diih, is conftrufted upon principles fo fimilar to thofe which are the foundation of our fingle microfcope by refleftion (fee AIicroscope,) that it may well be fupppofed to have given the hint to the ingeni¬ ous inventor of it. In 1702, Air Wilfon made feveral ingenious improve¬ ments in the method of ufing fingle magnifiers, for the purpofe of viewing tranfparent objefts •, and his micro¬ fcope, which is alfo a neceffary part of the folar micro¬ fcope, is in very general ufe at this day, (See {Micro¬ scope, feci. 1.). In 1710, Air Adams gave to the Royal Society the following account of his method of making fmall glo¬ bules for large magnifiers. He took a piece of fine •window-glafs, and cut it with a diamond into feveral flips, not exceeding f of an inch in breadth ; then, holding one of them between the fore-finger and thumb of each hand over a very fine flame, till the glafs began to foften, he drew it out till it was as fine as a hair, and broke ; then putting each of the ends into the pureft part of the flame, he had two globules, which he could increafe or diminifli at pleafure. If they were held a long time in the flame, they would have fpots on them, fo that he drew them out immediately after they be¬ came round. He broke oft' the ftem as near to the globule as he could, and lodging the remainder between the plates, in which holes were drilled exa&ly round, the microfcope, he fays, performed to admiration. Through thefe magnifiers the fame thread of very fine muflin appeared three or four times bigger than it did in the largeft of Air Wilfon’s magnifiers. I c s. The ingenious Air Grey hit upon a very eafy expe- Hiftory, dient to make very good temporary microfcopes, at a ' very little expence. They confift of nothing but fmall T ^ drops of water taken up with the point of a pin, and put microfCOp^ into a fmall hole made in a piece of metal. Thefe glo-by Mr bules of wTater do not, indeed, magnify fo much as thofe Grey, which are made of glafs of the fame fize, becaufe the refradlive power of -water is not fo great j but the fame purpofe will be anfwered nearly as well by making them fomewhat fmaller. The fame ingenious perfon, obferving that fmall he¬ terogeneous particles inclofed in the glafs of which mi¬ crofcopes are made, were much magnified W’hen thofe glafles were looked through, thought of making his mi¬ crofcopes of water that contained living animalcula, to fee how they would look in this new fituation •, and he found his fcheme to anfwer beyond his expeftation, fo that he could not even account for their being magnified fo much as they wrere : for it was much more than they would have been magnified if they had been placed be¬ yond the globule, in the proper place for viewing objefls. But Alontucla obferves, that, when any objetft is inclofed within this fmall tranfparent globule, the hinder part of it a£ls like a concave mirror, provided they be fitu- ated between that furface and the focus j and that, by this means, they are magnified above 3-i- times more than they would have been in the ufual way. Ioo Temporary microfcopes of a difterent kind have been Microfcop« conftrufted by Dr Brewfter. They were compofed of of t\ir pen- turpentine varnifli, which was formed into a piano-con- t'ne varni^ vex lens, by laying a drop of it upon a piece of plain glafs : the under furface of the glafs was then fmoked, and the black pigment removed immediately below, the fluid lens. Thefe lens lafted for a long time, and (hewed objefts diftinflly, even when combined into a compound microfcope. See Appendix to Fergufon's Lechtres, vol. ii. and AIicroscope, p. 19- H After the fuccefsful conftrudlion of the reflefting te- RefjC(r Accordingly we find two plans of this kind. The firft Barker. W'as that of Dr Robert Barker. His inftrument differs in nothing from the reflefting telefcope, excepting the diftance of the two fpeculums, in order to adapt it to thofe pencils of rays which enter the microfcope diverg¬ ing \ whereas they come to the telefcope from very di- ftant objefls nearly parallel to each other. This microfcope is not fo eafy to manage as thofe of the common kind. For vifion by reflection, as it is much more perfect, fo it is far more difficult than that by refraClion. Nor is this microfcope fo ufeful for any but very fmall or tranfparent objeCts. For the objeCt, being between the fpeculum and image, would, if it were large and opaque, prevent a due reflection. 1Q1 Dr Smith invented a double reflecting microfcope, j)r Smith's of which a theoretical and practical account is given inrefledting his remarks at the end of the fecond volume of his Sy-!P‘cr0/C0^ ftem of Optics. As it is conftruCted on principles dif-^J5^^^ ferent from all others, and in the opinion of fome, fu- perior to them all, the reader will not be difpleafed with the following practical defeription. A feCtion of this microfcope is {hewn in fig. 2. -where p[ate ABC and ab c are two fpecula, the former concave, and ccclxxv& the latter convex, inclofed within the tube DEFG. fig ^ The fpeculum ABC is perforated, and the objeCt to be viewed OPT Hiftory. viewed is fo placed between the centre and principal ' focus of that fpeculum, that the rays flowing from it to ABC are reflefted towards an imagery. But before that image is formed, they are intercepted by the con¬ vex fpeculum a b c, and thence refle&c^l through the hole BC in the vertex of the concave to a fecond image 7r x, to be viewed through an eye-glafs /. The objedt may either be fituated between the two fpecula, or, which is perhaps better, between the principal focus and vertex c of the convex fpeculum a b c, a fmall hole being made in its vertex for the tranfmifTion of the in¬ cident rays. When the microfcope is ufed, let the ob¬ ject be included between two little round plates of Mufcovy-glafs, fixed in a hole of an oblong brafs plate u m, intended to Hide clofe to the back fide of the con¬ vex fpeculum : which mufl: therefore be ground flat on that fide, and fo thin that the objefl may come pre- cifcly to its computed diftance from the vertex of the fpeculum. The Aider mufl be kept tight to the back of the metal by a gentle fpring. The diflance of the objeft being thus determined, diflinft vifion to different eyes, and through different eye-glaffes, muff be pi-ocur- ed by a gentle motion of the little tubes that contain thefe glaffes. Thefe tubes mull be made in the ufual form of thofe that belong to Sir Ifaac Newton’s refleft- ing tclefcope, having a fmall hole in the middle of each plate, at the ends of the tube, fituated exa'flly in each focus of the glafs: The ufe of thefe holes and plates is to limit the vifible area, and prevent any ftraggling rays from entering the eye. To the tube of the eye-glafs is faflened the arm g, on which the adjufling ferew turns. A fimilar arm u is attached to the fixed tube X, in which the neck of the ferew turns; and by turning the button //, the eye-tube is moved farther from or nearer to the objeft, by which means different forts of eyes obtain di- ftin£l vifion. The rays ivhich flow from the objefl direflly through the hole in the concave fpeculum and through the cye-glafs, by mixing with the refle£led rays, would dilute the image on the retina, and therefore mufl be intercepted. This is done by a very fimple contri¬ vance. 1 he little hole in the convex fpeculum is ground conical as in the figure ; and a conical folid P, of which the bafe is larger than the orifice in the back of the convex fpeculum, fupported on the flender pil¬ lar P^), is fo placed as to intercept all the direB rays from the eye-glafs. The’tubes are flrongly blacked on their infides, and likewife the conical folid, to hin¬ der all refle&ion of ray* upon the convex fpeeulum. The little bale, too, of the folid fhould be made concave, that whatever light it may Hill reflect, may be thrown back upon the objeeff ; and its back-fide being conical and blacked all over, will either abforb or laterally difperfe any flraggling rays which the concave fpeculum may fcatter upon it, and fo prevent their coming to the eye-glafs. Notwithflanding the interpofition of this conical folid, yet when the eye-glafs is taken out, diflant ob- jeils may be dillinclly feen through the microfcope, by rays reflefled from the metals, and diverging upon the eye from an image behind the convex fpeculum. But this mixture of foreign rays with thofe of the ob- jefl, wjiich is common to all kinds of microfcopes in viewing tranfparent objedls, is ufually prevented by ICS. 203 placing before the objefl a thick double convex lens /, Hiftory. to collefl the Iky-light exaflly upon the objedl. This "v " F lens fhould be juft fo broad as to fubtend the oppoftte angle to that which the concave fpeculum fubtends at the objedl. The annular frame of the lens mull be very narrow, and connedled with the microfcope by two or three flender wires or blades, whofe planes produced ♦ may pafs through the objedl, and intercept from it as little Iky-light as poflible. This is not the place for explaining the principles of this microfcope, or demonftrating its fuperiority over moft others ; nor are fuch explanation and demonllra- tion neceffary. Its excellence, as well as the principles upon which it is conftrufted, will be perceived by the reader, when he has made himfelf mailer of the laws of refraction and reflection as laid down in the fequel of this article. M. Lieberkuhn, in 1738 or 1739, made two capi-Soj tal improvements in microfcopes, by the invention oferofcope, thefolar microfcope, and the microfcope for opaque objeBs. and that for When he was in England in the winter of 1739, he?Pacluc0'3“ fliowed an apparatus for each of thefe purpofes, made by^c<^s‘ himfelf, to leveral gentlemen of the Royal Society, as well as to fome opticians. The microfcope for opaque objeCls remedies the in¬ convenience of having the dark fide of an objeCt next the eye. For by means of a concave fpeculum of fil- ver, highly poliflied, in the centre of which a magni¬ fying lens is placed, the objeCl is fo ftrongly illumi¬ nated tljat it may be examined with all imaginable eafe and pleafure. A convenient apparatus of this kind, with four different fpecula and magnifiers of different powers, was brought to perfeClion by Mr Cuff in Fleet- ftreet. M. Lieberkuhn made confiderable improvements in his folar microfcope, particularly in adapting it to the view of opaque objeCls ; but in what manner this was effeCled, M. Atpinus, who was highly entertained with the performance, and who mentions the faCl, was not able to recolleCl; and the death of the ingenious inventor prevented his publithing any account of it him¬ felf. M. Atpinus invites thofe who came into the pof- feflion of M. Lieberkuhn’s apparatus to publiffi an ac¬ count of this inilrument; but it does not appear that his method was ever publilhed. This improvement of M. Lieberkuhn’s induced M. iEpinus himfelf to attend to the fubjeCl ; and he thus produced a very valuable improvement in this inilru- mtnt. For by throwing the light upon the forefide of any objeCl by means of a mirror, before it is tranfmit- ted through the objeCl-lens, all kinds of objeCls are equally well reprefented by it. 104 M. Euler propofed to introduce vifion by refle&ed Refle<^e(* light into the magic lantern and folar microfcone, by \s“t1mtr0“ which many inconveniences to which thofe inllruments tll# mitro- are fubjeCl might be avoided. For this purpofe, he fays,fcope and that nothing is neceffary but a large concave mirror, maSlc lan" perforated as for a telefcope ; and the light fliould befotern’ fituated, that none of it may pafs direCtly through the perforation, fo as to fall on the images of the objeCls upon the ftreen. He propofes to have four different machines, for objeCls of different fixes; the firff for thofe of fix feet long, the fecond for thofe of one foot, the third for thofe of two inches, and the fourth for thofe of two lines ; but it is needlefs to be particular in the de- C c 2 feription 204 Iliftory. 505 Mr Mar¬ tin’s im¬ provement in the iolar niicrofcope to5 Di Torre’s extraordi¬ nary mag¬ nifying mi- crofcope. 107 Tould not he ufed by Mr Baker. DPT feripttott of thtie, as ttlorc jjel'ife’61 Iinlrllnients are de¬ fer! bed under the article MltRoStoPEs. Several irnproveihtiits were hiade in the apparatus to the folar Oiicrofcbpe^ sis adapted to view opaque objefh, by M. Zeilrer, who made one conftruction for the larger kind of objedts, and another for the fmall ones, Mr Martin having conftrudled a folar microfcope of a larger fize than common, for his own ufe, the illumi¬ nating lens being 4^ inches in diameter, and all the other parts of the inilrument in proportion, found, that by the help of an additional part, which he does not deferibc, he could fee even opaque objedts very well. If he had made the lens any larger, he was aware that the heat produced at the focus w'ould have been too great for moft objedts to bear. The expence of this in- itrument, he fays, does not much exceed the price of the common folar microfcope. The fmalleft globules, and confequently the greateft ntagnifiers, for microfcopes, that have yet been execu¬ ted, were made by T. Di Torre of Naples, who, in 1765, fent four of them to the Royal Society. The largell: of them was only two Paris points in diameter, and it was faid to magnify the diameter of an objedt 640 times. The fecond was the fize of one Paris point, and the third w?as no more than half of a Paris point, or the 144th part of an inch in diameter, and was faid to magnify the diameter of an objedf 2560 times. One of thefe globules was wanting when they came into the hands of Mr Baker, to whofe examination tlaey were fubmitted by the Royal Society. This gentleman, how* 1 c s. ever, was not able to make any ufe of thefe. With that which magnifies the lead, he was not able to fee any objedt with fatisfaction ; and he concludes his ac¬ count with expreding his hopes only, that, as his eyes had been much ufed to microfcopes, they were not in¬ jured by the attention he had given to them, though he believed there were few' perfons who w’ould not have been blinded by it. The condrudfion of a telefcope with fix eye-glafles led M. Euler to a fimilar confirudiion of microfcopes, by introducing into them fix lenfes, one of which ad* mits of fo fmall an aperture, as to ferve, indead of a diaphragm, to exclude all foreign light, though, as he fays, it neither lefiens the field of view, nor the bright- nefs of objedts. The improvement of all dioptric indruments is great¬ ly impeded by inequalities in the fubdance of the glafs of which they are formed ; but though many attempts have been made to make glafs without that imper¬ fection, none of them have been hitherto quite effec¬ tual. M. A. D. Merklein, having found fome glafs which had been melted when a building was on fire, and which proved to make excellent objedt-glafles for telefcopes, concluded that its peculiar goodnefs arol’e from its not having been difturbed when it was in a fluid ftate ; and therefore he propofed to take the metal out of the furnace in iron veffels, of the fame form that was wanted for the glafs j and after it had been perfedtly fluid in thofe veflels, to let it ftand to cool, without any difturbance. This, however, is not always found to anfwer. Hiftcry. 10S Difficultly attending the con¬ ftruction of dioptric in- ftruments. PART I. THEORY OF OPTICS. THE feienee of optics is commonly divided into three parts, Dioptrics, which treats of the laws of re¬ fraction, and the phenomena depending upon them } Catoptrics, which treats of the laws of reflection, and the phenomena connected with them ; and, laftly, Chromatics, which treats of the phenomena of colour. But this divifion is of no ufe in a treatife of Optics, as molt of the phenomena depend both on refraCtion and reflection, colour itfelf not excepted. For this reafon, though we have given detached articles under the words .Dioptrics, Catoptrics, and Chromatics; we have referved for this place the explanation of the law's of reflection and refraCtion, by w'hich all optical phenome¬ na may be explained. Chap. I. On Light. Under the article Light we have given fome ac- count of the controverfies concerning its nature. The opinions of philofophers may, in general, be arranged 109 under thefe^ two : 1. That light is produced by the un- Difftrent dulations of an elaltic fluid, nearly in the fame manner epmions as found, is produced by the undulations of the air. coneeinin- This opinion was firft offered to the public by Des oflielit!1 Cartes, and afterwards by Mr Huygens. It was re¬ vived by Euler, and has lately found an able and inge¬ nious defender in Dr Thomas Young—2d, That the phenomena of vifion are produced by the motion and aCtion of matter emitted from the fliining body with immenfe velocity, moving uniformly in ftraight lines, and aCted on by other bodies; fo as to be reflected, re- fraCted, or infleCted, in various ways, by means of forces which aCt on it in the fame manner as on other inert matter. Sir Ifaac Newton has ably ihown the diflimila- rity between the phenomena of vifion and the legitimate confequences of the undulations of an elaftic fluid. All M. Euler’s ingenious and laborious difeuflions have not removed Newton’s objections in the fmalleft degree. Sir Ifaac adopts the vulgar opinion, therefore, becaufe the difficulties attending this opinion are not ineonfiftent with the eftabliflied principles of mechanics, and are merely difficulties of conception to limited faculties like ours. We need not defpair of being able to decide, by experiment, which of thefe opinions is neareft to the truth ; becaufe there are phenomena where the refult fliould be fenfibly different in the two hypothefes. At prefent, we ftiall content ourfelves with giving fome ac¬ count of the legitimate confequences of the vulgar opi¬ nion, as modified by Sir Ifaac Newton, viz. that light confifts of fmall particles emitted with very great velo- city, and attraCled or repelled by other bodies at very no fmall diflances. Light iflues Every vifible body emits or refleCls inconceivably !n ftrafight fmall particles of matter, from each point of its furface, 5 point which iffue from it continually., not unlike fparks from in a lumi- a coal, in ftraight lines and in all directions. Thefe nous fur* particles Theory. OPT KefracTion. particles entering the eye, and ftriking upon the retina (an expanfion of the optic nerve over the back part of the eye to receive their impulfes), excite in our minds the idea of light. And according as they differ in iubftance, denflty, velocity, or magnitude, they produce in us the ideas of different colours j as will be explained in its proper place. That the particles %hich conflitute light are exceed¬ ingly fmall, appears from this, that if a hole be made through apiece of paper with a needle, rays of light from every objeft on the farther fide of it are capable of being tranfmitted through it at once without the leaf! confufion *, for any one of thofe objefts may as clearly be feen through it, as if no rays paffed through it from any of the reft. Befides, if a candle is lighted, and there be no obftacle in the way to obftru celerated during its paflfage through the fpace in which that attraction exerts itfelf; and therefore, after it has* paffed that fpace, it will move on, till it arrive at the oppofite fide of the medium, with a greater degree of velocity, than it had before it entered. So that in this cafe its velocity only will be altered. Whereas, if a ray enters a denier medium obliquely, it will not only- have its velocity augmented thereby, but its direction will become lefs oblique to the furface. Juft as when a ftone is thrown downwards obliquely from a precipice, it falls to the furface of the ground in a direction near¬ er to a perpendicular one, than that with which it was thrown from the hand. Hence we fee a ray of light, in palling out of a rarer into a denfer medium, is refraCled towards the perpendicular ; that is, fuppofing a line drawn perpendicularly to the furface of the me¬ dium, through the point where the ray enters, and ex¬ tended both ways, the ray in paffmg through the fur? face is refraCled or bent towards the perpendicular line ; or, which is the fame thing,, the line which it deferibes by its motion after it has paffed through the furface, makes a lefs angle with the jjerpendicular, than the line which it deferibed before. Thefe pofitions may be il-» luftrated in the following manner. Let us fuppofe firft,' that the ray palles out of a va- Plats cuum into the denfer medium ABCD (fig. 3.), andCCCLXXVI3: that the attractive force of each particle in the medium Flg‘ is extended from its refpeCtive centre to a diftance equal to that which is between the lines AB and EF, or AB and GH ; and let KL be the path deferibed by a ray of light in its progrefs towards the denfer me? dium. This ray, when it arrives at L, will enter the fphere of attraClion of thofe particles which lie in AB the furface of the denfer medium, and will therefore ceafe to proceed any longer in the right line KLM, but will be diverted from its courfe by being attraCled to? wards 206 OPT t'aufe of wards the line AB, and will begin todefcribe the curve Refraction, palling through the furface AB in home new di- region, as O^) j making a lefs angle with a line PH, drawn perpendicularly through the point N, than it would have done had it proceeded in its firfl: diredlion KLM. As w'e have fuppofed the attraftive force of each par¬ ticle to be extended through a fpace equal to the di- * fiance between AB and EF, it is evident that the ray, after it has entered the furface, will Hill be attradled dowmvards, till it has arrived at the line EF ; for, till then, there will not be fo many particles above it which will attradl it upwards, as below, that will attradl it downwards. So that after it has entered the furface at N, in the diredlion ()£), it will not proceed in that direction, but will continue to defcribe a curve, as NS ; after which it Avill proceed flraight on towards the op- polite fide of the medium, being attradled equally every U'ay ; and therefore wfill at laft proceed in the direction XST, Hill nearer the perpendicular PR than before. If we fuppofe ABZY not to be a vacuum, but a ra¬ rer medium than the other, the cafe will flill be the fame ; but the ray will not be fo much refradted from its redlilineal courfe, becaufe the attraftion of the par¬ ticles of the upper medium being in a contrary direc¬ tion to that of the attradlion of thofe in the lorver one, the attradlion of the denfer medium wall in fome mea- fure be deftroyed by that of the rarer. When a ray, on the contrary, paffes out of a denfer into a rarer medium, if its diredtion be perpendicular to the furface of the medium, it will only lofe fome what of its velocity, in palling through the fpaces of attrac¬ tion of that medium (that is, the fpace wherein it is at- tradled more one way than it is another). If its direc¬ tion be oblique, it will continually recede from the per¬ pendicular during its paffage, and by that means have its obliquity increafed, juft; as a ftone thrown up obliquely from the furface of the earth increafes its obliquity all the time it rifes. Thus, fuppofing the ray TS palling out of the denfer medium ABCD into the rarer ABZY, when it arrives at S it will begin to be attract¬ ed downwards, and fo will defcribe the curve SNL, and then proceed in the right line LK *, making a larger angle with the perpendicular PR, than the line TSX in ■which it proceeded during its palfage through the other medium. We may here make a general obfervation on the for¬ ces which produce this deviation of the rays of light from their original path. They arife from the joint aftion of all the particles of the body which are fuffi- ciently near the particle of light", that is, whofe diftance from it is not greater than the line AE or G A •, and therefore the whole force which a£ls on a particle in its different fituations between the planes GH and EF, fol¬ lows a very different law from the force exerted by one particle of the medium. T he fpaee through which the attraftion of cohefion of the particles of matter is extended is fo very fmall, that in confidering the progrefs of a ray of light out of one medium into another, the curvature it deferibes in paffmg through the fpace of attra&ion is generally negletted ; and its path is fuppofed to be bent, or re- ffadled, only in the point where it enters the denfer medium. x I C S. Part I. Now the line which a ray deferibes before it enters Law of a denfer or a rarer medium, is called the incident ray; jfr'fraftion. and that which it deferibes after it has entered, is the ref rafted ray. The angle comprehended between the incident ray and the perpendicular, is the angle of incidence; and that between the refradled ray and the perpendicular, is the angle of refraftion. There is a certain and immutable law, by which refraftion is always performed; which is this : What¬ ever inclination a ray of light has to, the furface of any medium before it enters it, the degree of refrac¬ tion will always be fuch, that the fine of the angle of incidence and that of the angle of refraftion, will always have a conftant ratio to one another in that medium. Plate To illuftrate this : Let us fuppofe ABCD (fig. 4.) CCCLXxvir to reprefent a rarer, and ABEF a denfer medium : let 4' GH be a ray of light patting through the firft and en¬ tering the fecond at H, and let HI be the refrafted ray: then fuppofing the perpendicular PR drawn through the point H, on thexentre H, and with any radius, de¬ fcribe the circle ABPR; and from G and I, where the incident and refrafted rays cut the circle, let fall the lines GK and IL perpendicularly upon the line PR ; the former of thefe will be the fine of the angle of in¬ cidence, the latter of refraftion. Now if in this cafe the ray GH is fo refrafted at H, that GK is double or triple, &c. of IL, then, whatever other inclination the ray GH might have had, the fine of its angle of inci¬ dence would have been double or triple, &c. to that of its angle of refraftion. For inftance, had the ray paf- fed in the line MH before refraftion, it Avould have paf- fed in fome line as HN afterwards, fo fituated that MO thould have been double or triple &c. of N£). The following table contains the refraftive denfities of feveral bodies. Diamond, - 2.500 Flint-glafs, - l‘S^5 Plate glafs, - - 1-502 Crown glafs, - I*525 Sulphuric acid, - I-435 Solution of potafti, I-39° Olive oil, - 1.469 Alcohol, - 1.370 Atmofpheric air, 1.000276 Ice, - - 1.31 Water, - I>336 This relation of the fine of the angle of incidence to that of refraftion, which is a propofition of the moft ex- tenfive ufe in explaining the optical phenomena on phy- fical or mechanical principles, may be demonftrated in the following eafy and familiar manner. Lemma I. The augmentations or diminutions of the fquares of the velocities produced by the uniform ac¬ tion of accelerating or retarding forces, are pro¬ portional to the forces, and to the fpaces along which they aft, jointly *, or are proportional to the produfts of the forces multiplied by the fpaces. Let two bodies be uniformly accelerated from a ftate of reft in the points Ac, along the fpaces AB, ab, fig. 5. Fig. $. by Theory. OPT Law of by the accelerating forces Fand let AC, a c, be Refrartioru fpaces defcribed in equal times j it is evident, from what ^ Fas been faid under the articles Gravity and Acce- Fig- 5. ITERATION, that becaufe thefe fpaces are defcribed with motions uniformly accelerated, AC and a c are refpec- tively the halves of the fpaces which would be uniform¬ ly defcribed during the fame time with the velocities acquired at C and c, and a’re therefore meafures of thefe velocities. And as thefe velocities are uniformly acquired in equal times, they are meafures of the accelerating forces. Therefore, AC : a crrrF : f. Alfo, from the nature of uniformly accelerated motion, the fpaces are proportional to the fquares of the acquired velocities. Therefore, (ufing the fymbols \/"C, ^/*c, &c. to ex- prefs the fquares of the velocities at C c, &c.) we have : X/*C=AB : AC -y/1 C : c = AC1 : nc* -y/* c : >yib—ac\ab Therefore, by equality of compound ratios V'* B : AB X AC : a^X«G=ABxF: ab^f And in like manner y/1 D : ^id y/AD x F : ody^f; and y/1^—: y/2 b—y/1 r/rzBD X F :bdyf E. D. Corollary. If the forces are as the fpaces inverfe- ly, the augmentations or diminutions of the fquares of the velocities are equal. Remark. If DB, db, be taken extremely fmall, the produfts BD X F and bdy /'may be called the momen¬ tary a&ions of the forces, or the momentary increments of the fquares of the velocities. It is ufually exprelfed, by the writers on the higher mechanics, by the fymbol f s, or f ds, where f means the accelerating force, and .r or ds means the indefinitely fmall fpace along which it is uniformly exerted. And the propofition is exprefled by the fluxionary equation= becaufe vv is half the increment of v%, as is ivell known. Lemma II. Plate ^ a particle of matter, moving with any velocity ccclxxvii along the line AC, be impelled by an accelerat- ing or retarding force, a&ing in the fame or in the oppofite direction, and if the intenfity of the force in the different points B, F, H, C, &c. be as the ordinates BD, FG, &c. to the line DGE, the areas BFGD, BHKD, &c. will be as the changes made on the fquare of the velo¬ city, at B, when the particle arrives at the points F, H, &c. For let BC be divided into innumerable fmall por¬ tions, of which let FH be one, and let the force be fup- pofed to a£l uniformly, or to be of invariable intenfity during the motion along FH *, draw GI perpendicular to HK : It is evident that the redlangle FHIG will be as the produff of the accelerating force by the fpace along which it a£ts, and will therefore exprefs the mo¬ mentary increment of the fquare of the velocity. (Lem¬ ma 1.). The fame may be faid of every fuch reflangle. And if the number of the portions, fuch as FH, be in- creafed, and their magnitude diminifhed without end, the reffangles will ultimately occupy the whole curvili- neal area, and the force will therefore be as the finite I C vS. 207 changes made on the fquare of the velocity, and the propofition is demonftrated. Corollary. The whole change made on the fquare of the velocity, is equal to the fquare of that velocity ■which the accelerating force would communicate to the particle by impelling it along BC from a Hate of reft in B. For the area BCED will ftill exprefs the fquare of this velocity, and it equally exprelfes the change made on the fquare of any velocity wherewith the particle may pafs through the point B, and is independent on the magnitude of that velocity. Remark. The figure is adapted to the cafe where the forces all confpire with the initial motion of the particle, or all oppofe it, and the area expreffes an aug¬ mentation or a diminution of the fquare of the initial velocity. But the reafoning would have been the fame, although, in fome parts of the line BC, the forces had confpired with the initial motion, and in other parts had oppofed it. In fuch a cafe, the ordinates which exprefs the intenfity of the forces muft lie on different fides of the abfeifla BC, and that part of the area which lies on one fide muft be confidered as negative with refpeft to the other, and be fubtrafted from it. Thus, if the for¬ ces be reprefented by the ordinates of the dotted curve line DH e, which croffes the abfeiffa in H, the figure will correfpond to the motion of a particle, which, after moving uniformly along AB, is fubjeded to the a£Hon of a variable accelerating force during its motion along BH, and the fquare of its initial velocity is increafed by the quantity BHD ; after which it is retarded during its motion along HC, and the fquare of its velocity in H is diminilhed by a quantity HC e. Therefore the fquare of the initial velocity is changed by a quantity BHB—HC f-, or HC e—BHD. This propofition, which is the 39th of the ift book of the Principia, is perhaps the molt important in the whole fcience of mechanics, being the foundation of every application of mechanical theory to the explana¬ tion of natural phenomena. No traces of it are to be found in the writings of philofophers before the publi¬ cation of Newton’s Principia, though it is afiumed by John Bernoulli and other foreign mathematicians, as an elementary truth, without any acknowledgment of their obligations to its author. It is ufually expreffed by the equation f s~vv and ffs=v*, i. e. the fum of the mo¬ mentary actions is equal to the whole or finite increment of the fquare of the velocity. Law of Refraction. Proposition. 113 When light paffes obliquely into or out of a tranf- The ratio parent fubftance, it is refracted fo that the fine of the angle of incidence is to the fine of the t0 the fine angle of refra&ion in the conftant ratio of theofrefrac- velocity of the refracted light to that of thetl0n* incident light. Let ST, KR, reprefent two planes (parallel to, and Plate equidiftant from, the refratting furface XY) whichCCfig^.VU bound the fpace in which the light, during its paffage, is afted on by the refracting forces. The intenfity of the refraCting forces being fuppofed equal at equal diftances from the bounding planes, though anyhow different at different diftances from them, may be reprefented by the ordinates T #, n q,p r, c R, &c. of the curve a b np c, of which the form muft be .208 o p T La.wof 'kg determined from dbfervatkm, and may remain for , 'cha^‘on; ever unknown. The phenomena of infledted light fhow v -us that it is attrafted by the refrafting fubftance at fome •- -diftances, and repelled at others. Let the light, moving uniformly in the diredtion AB, enter the refrafting ftratum at B. It will not " proceed in that diredtion, but its path will be incur- vated upwards, while adted on by a repulfive force, and downwards, while impelled by an attractive force. It will defcribe fome curvilincal path B d a CDE, which AB touches in B, and will finally emerge from the refradting ftratum at E, and move uniformly in a ftraight line EF, which touches the curve in E. If, through b, the interfedtion of the curve of forces with its abfciffa, we draw b o, cutting the path of the light in o, it is evident that this path wrill be concave up¬ wards between B and o, and concave downward* be¬ tween o and E. Alfo, if the initial velocity of the light has been fufficiently fmall, its path may be fo much bent upwards, that in fome point d its diredlion may be parallel to the bounding planes. In this cafe it is evident, that being under the influence of a repulfive force, it will be more bent upwards, and it will de¬ fcribe df equal and fimilar to d B, and emerge in an angle gfs, equal to ABG. In this cafe it is refledted, making the angle of refledlion equal to that of inci¬ dence. By which it appears how refledtion, refradlion, and infledlion, are produced by the fame forces and performed by the fame laws. But let the velocity be fuppofed fufficiently great to enable the light to penetrate through the refradling ftratum, and emerge from it in the diredtion EF; let AB and EF be fuppofed to be defcribed in equal times : They will be proportional to the initial and final velo¬ cities of the light. Now, becaufe the refradting for¬ ces ?7iufl adt in a diredtion perpendicular to the refradt¬ ing furface (fince they arife from the joint adtion of all the particles of a homogeneous fubftance which are within the fphere of mutual adtion), they cannot af- fcdt the motion of the light eftimated in the diredtion of the refradting furface. If, therefore, AG be drawn per¬ pendicular to ST, and FK to KR, the lines GB, EK, muft be equal, becaufe they are the motions AB, EF, eftimated in the diredtion of the planes. Draw now EL parallel to AB. It is alfo equal to it. Therefore, EL, .EF, are as the initial and final velocities of the light. But EF is to EL as the fine of the angle ELK to the fine of the angle EFK 5 that is, as the fine of the angle ABH to the fine of the angle FEI •, that is, as the fine of the angle of incidence to the fine of the angle of re¬ fradlion. By the fame reafoning it will appear that light, mov¬ ing in the diredlion and with the velocity FE, will de¬ fcribe the path EDB, and will emerge in the diredlion and with the velocity BA. . Let another ray enter the refradling ftratum perpen¬ dicularly at B, and emerge at Q. Take two points N, P, in the line B£), extremely near to each other, fo that the refradling forces may be fuppofed to adl uni¬ formly along the fpace NP : draw NC, PD, parallel to ST, CM perpendicular to DP, and MO perpendicular to CD, which may be taken for a ftraight line. Then, becaufe the forces at C and N are equal, by fuppofition they may be reprefented by the equal lines CM and NP. The force NP is wholly employed in accelerating the I c s. Part I. light along NP j but the force CM being tranfverfe to Law of the motion BD, is but partly fo employed, and may be fttfta&ion. conceived as arifing from the joint adtion of the forces ’ J CO, OM, of which CO only is employed in accelerat¬ ing the motion of the light, while OM is employed in incurvating its path. Now it is evident, from the fimi- larity of the triangles DCM, MCO, that DC : CMrr CM: CO, and that DC X CO—CM X CM—NP X NP. But DC X CO and NP xNP are as the produdts of the fpaces by the accelerating forces, and exprefs the mo¬ mentary increments of the fquares of the velocities at C and N. (Lemma 1.). Thefe increments, therefore, are equal. And as this muft be faid of every portion of the paths BCE and BNQ, it follows that the whole incre¬ ment of the fquare of the initial velocity produced in the motion along BCE, is equal to the increment pro¬ duced in the motion along BNO. And, becaufe the initial velocities were equal in both paths, their fquares were equal. Therefore the fquares of the final veloci¬ ties are alfo equal in both paths, and the final velocities themfelves are equal. The initial and final velocities are therefore in a conftant ratio, whatever are the di- redtions 5 and the ratio of the fines of the angles of incidence and refradlion being the ratio of the veloci¬ ties of the refradled and incident light, by the former cafe of Prop. 1. is alfo conftant. Remark. The augmentation of the fquare of the initial velocity is equal to the fquare of the velocity whieir a particle of light woufd have acquired, if im¬ pelled from a ftate of reft at B along the line BQ. (Corol. of the Lemma 2.), and is therefore indepen¬ dent on the initial velocity. As this augmentation is exprefled by the curvilineal area a T b np c R, it depends both on the intenfity of the refradling forces, exprefled by the ordinates, and on the fpace through which they adl, viz. TR. Thefe circumftances arife from the na¬ ture of the tranfparent fubftance, and are charadleriftic of that fubftance. Therefore, to abbreviate language, we (hall call this the fpecific velocity. This fpecific velocity is eafily determined for any fubftance in which the refradlion is obferved, by draw¬ ing L i perpendicular to EL, meeting in /’the circle defcribed with the radius EF. For E i being equal to EF, will reprefent the velocity of the refradled light, and EL reprefent the velocity of the incident light, and L/rrEL1-}-L z1, and therefore Lz’l is the aug¬ mentation of the fquare of the initial velocity, and L i is the fpecific velocity. It will now be proper to deduce fome corollaries from thefe propofitions, tending to explain the chief phenomena of refradtion. Cor. 1. When light is refradled towards the per pen- dicular to the refradling furface, it is accelerated 5 and it 0f i*ght°ac. is retarded when it is refradled from the perpendicular, ederated or In the firft cafe, therefore, it muft be confidered asretart3e(i by having been adled on by forces confpiring (in part at re^ra(^'0I!' leaft) with its motion, and vice verfa. Therefore, be¬ caufe we fee that it is always refradled towards the per¬ pendicular, when paffing from a void into any tranfpa¬ rent fubftance, we mull conclude that it is, on the whole, attradled by that fubftance. We muft draw the fame conclufion from obferving, that it is refradled from the perpendicular in its paflage out of any tranf¬ parent lubftance whatever into a void. It has been at¬ tradled backwards by that fubftance. This Theory. OPTICS. Law of Reft idlion Tins acceleration of liglit in refraction is contrary to the opinion of tlioie philofophers who maintain, that illumination is produced by the undulation of an elaitic medium. Euler attempts to prove, by mecha¬ nical laws, that the velocities of the incident and re- fiafted bght, are proportional to the fines of incidence and refraction, while our principles make them in this ratio inverfely. Bofeovich propofed a fine experiment for deciding this queition. 1 he aberration of the fixed flars arifes from the combination of the motion of light with the motion of the teleicope by which it is obierv- ed. Therefore this aberration thould be greater or lefs when obferved by means of a teleicope filled with water, according as light moves flower or fwifter through wa¬ ter than through air. He was miflaken in the manner in which the conclufion fhould be drawn from the ob- fervation made in the form preferibed by hirn : and the experiment has not yet been made in a convincing man¬ ner } becaufe no fluid has been found of fuffieient tranf parency to admit of the neceflary magnifying power. It is an experiment of the greateft importance to optical fcience. Cor. 2. If the light be moving within the tranfparent fubftance, and if its velocity (ertimated in a dire&ion perpendicular to the furface) do not exceed the fpecific velocity of that fubftance, it will not emerge from it, but will be reflefted backwards in an angle equal to that of its incidente. For it muft be obferved, that in Plate ike figure of laft propofition, the' excefs of the fquare ccLxxvn.of EF above the fquare of EL, is the fame with the % s- excefs of the fquare of KF above the fquare of KL. Therefore the (quare of the fpecific velocity is equal to the augmentation or diminution of the fquare of the per¬ pendicular velocity. If therefore the initial perpendi¬ cular^ velocity ^ FK be precifely equal to the fpecific velocity, the light will juft reach the farther fide of the attra&ing ftratum, as at B, where its perpendicular velocity will be completely extinguiftied, and its motion will be in the dire&ion BT. But it is here under the influence of forces tending towards the plane KR, and its motion will therefore be ftill incurvated towards it ; and it will deferibe a curve BD equal and fimilar to EB, and finally emerge back from the refraining ftra¬ tum into the tranfparent fubftance in an angle RDA equal to KEF. S If ^ the direction of the light be ftill more oblique, fb that its perpendicular velocity is lefs than the fpecific velocity, it will not reach the plane ST, but be re- fl^iRed as foon as it has penetrated fo far that the fpe¬ cific velocity of the part penetrated (eftimated by the compounding part of the area of forces) is equal to its perpendicular velocity. Thus the ray/E will deferibe the path EdD a penetrating to b d, fo that the corre¬ sponding area of forces a bee is equal to the fquare of jk, its perpendicular velocity. The extreme brilliancy of dew drops and of jewels had often excited the attention of philofophers, and it always appeared a difficulty how light was refle&ed at all from the pofterior furface of tranfparent bodies. It afforded Sir Ifaac Newton his ftrongeft argument agamft the ufual theory of refleftion, viz. that it was produced by impadl on folid elaftic matter. He was the firft.who took notice of the total refle&ion in great obliquities ; and very properly afleed how it can be faid Vol. XV. Part I. 209 that there is any impa& in this cafe, or that the refled- Law g ing ini pad ftiould ceafe at a particular obliquity ? RefrarL It muft be acknowledged that it is a very curious circumftance, that a body which is pcrfe&ly tranlpa- HSyc ^ a rent fhould eeafe to be. io at a certain obliquity } that certain 00- a great obliquity ftiould not hinder light from paffing ’T* [y ve from avoid into a piece of glafs ; but that the lame obliquity Ihould prevent it from paffing from the giakirL! parerit into a void. The fineft experiment for illuftrating the fubltances. fad is, to take two pieces of mirror-glafs, not lilvered, and put them together with a piece of paper between them, forming a narrow margin all round to kvep them apart. Plunge this apparatus into water. When it is held nearly parallel to the furface of the water, every thing at the bottom of the veffel will be feen clearly through the glaffes j but when they are turned fo as to be inclined about 50 degrees, they will intercept the light as much as if they were plates of iron. It will be proper to foak the paper in varnifti, to prevent water from getting between the glaffes. IJ6- What is called the brilliant cut in diamonds, is fuch The bri!~ a difpofition of the pofterior facets of the diamond, li.ant cut iu that the light is made to fall upon them fo obliquely dla"i0nds that none of it can go through, but all is refleded. tai reflecl°* To produce this effed in the greateft poffible degree istion. a matter of calculation, and merits the attention of the lapidary. When diamonds are too thin to admit of this form, they are cut in what is called the rofe faftiion. This has a plain back, and the facets are all on the front, and fo difpofed as to refrad the rays into fuffici- ent obliquities, to be ftrongly refleded from the pofterior plane. Doublets are made by cutting one thin diamond rofe faftiion, and another fimilar one is put behind it, with their plane furfaces joined. Or, more frequentlv, the outfide diamond has the anterior facets of the bril¬ liant, and the inner has the form of the inner part of a brilliant. If they be joined with very pure and ftrong* ly refrading varniffi, little light is refleded from the feparating plane, and their brilliancy is very confider- able, though ftill inferior to a true and deep brilliant. If no varnilh be ufed, much of the light is refleded from the flat fide, and the efftd of the pofterior facets is much diminifhed. But doublets might be conftrud- ed, by making the touching furfaces of a fpherical form (of which the curvature ftiould have a due pro¬ portion to the fize of the ftone), that would produce an effed nearly equal to that of the moft perfed brilliant. t f Cor. 3. Since the change made on the fquare of the Refraftion velocity of the incident light is a conftant quantity, it diminiflies follows, that the refradion will diminifti as the velocity f the ijici: of the incident light increafes. For if L fin fig. 7. ty mercafe*’ be a conftant quantity, and EL be increafed, it is evi- * dent that the ratio of E 2, or its equal EF, to EL will be diminiftied, and the angle LEF, which conftitutes the refradion, will be diminiftied. The phyfical caufe of this is eafily feen : When the velocity of the incident light is increafed, it employs lefs time in paffing through the refrading ftratum or fpace between the planes ST and KR, and is therefore lefs influenced by the refrac¬ ting forces. A fimilar effed would follow if the tranf¬ parent body were moving with great velocity, towards’ the luminous body. Some naturalifts have accounted for the different re* D d frangibility 210 OPT Law of frangibility of the differently coloured rays, by fuppo- Refratftion. gng. t}iat t]ie rt,(i rayS move with the greateft rapidity, and they have determined the difference of original ve¬ locity which would produce the obfervcd difference of refradlion. But this difference would be obfeived in 118 The refrac¬ tion of a fbar greater in the even¬ ing than in the morn¬ ing. Jip All light fubjedl to the fame laws. the eciipfes of Jupiter’s fatellites. They fbould be ruddy at their immerfions, and be fome feconds before they at¬ tain their pure whiteriefs; and they Ihould become bluifh immediately before they vanifh in emerfions. '1 his is not obferved. Befides, the difference in refrangibility is much greater in flint glafs than in crown glals, and this would require a proportionally greater difference in the original velocities. 1 he explanation therefore mult be given up. It fhould follow, that the refraction of a ftar which is in our meridian at fix o’clock in the evening Ihould be greater than that of a Itar which comes on the me¬ ridian at fix in the morning 5 becaufe we are moving away from the firft, and approaching to the laft. But the difference is but xo’Vo of the whole, and cannot be obferved with fufficient accuracy in any way yet prae- tifed. A form of obfervation lias been propofed by Dr Blair, profeffor of practical aftronomy in the univerfity of Edinburgh, which promifes a very fenfible difference of refraCtion. It is alfo to be expeCted, that a differ¬ ence will be obferved in the refraCtion of the light from the eaft and weflern ends of Saturn’s^ring. Its diame¬ ter is about 26 times that of the earth, and it revolves in 1 oh. 32' } fo that the velocity of its edge is about of the velocity of the fun’s light. If therefore the light be reflected from it according to the laws of perfeCl elailicity, or in the manner here explained, that which comes to us from the weftern extremity will move more {lowly than that which comes from theeaft- ern extremity in the proportion of 2500 to 25OT. And if Saturn can be feen diftinCtly after a refraCtion of 30° through a prifm, the diameter of the ring will be in- creafed one half in one pofition of the telefcope, and will be as much diminithed by turning the telefcope half round its axis •, and an intermediate pofition will exhibit the ring of a diftorted fliape. This experiment is one of the molt interefting to optical fcience, as its refult will be a levere touch done of the theories which have been attempted for explaining the phenomena on mechanical principles. If the tail of a comet be impelled by the rays of the fun, as is fuppofed by Euler and others, the light by which its extreme parts are feen by us muff have its ve¬ locity greatly diminiftied, being refiefted by particles which are moving away from the fun with immenfe rapidity. This may perhaps be difeovered by its great¬ er aberration and refrangibility. As common day light is nothing but the fun’s light refleded from terreftrial bodies, it is reafonable to ex- peCt that it will fuffer the fame refraCtion. But no¬ thing but obfervation could affure us that this would be the cafe with the light of the {tars 5 and it is rather furprifing that the velocity of their light is the fame with that of the fun’s light. It is a circumftanc.e of con¬ nexion between the folar fy'ftem and the reft of the uni- verfe. It was as little to be looked for on the light of terreftrial luminaries. If light be conceived as fmall particles of matter emitted from bodies by the aCfion of accelerating forces of any kind, the vaft diverfity which we obferve in the conftitution of fublunary bodies fliould ICS. Parti. make us expect differences in this particular. Yet it is Law oi found, that the light of a candle, of a glow worm, &c, Kefraftfon. fuffers the fame refraCtion, and confiits of the fame co- lours. This circumftance is adduced as an argument againft the theory of emiftion. It is thought more probable that this famenefs of velocity is owing to the nature of the medium, which determines the frequen¬ cy of its undulations and the velocity of their propa¬ gation. Cor. 4. When two tranfparent bodies are contiguous, Lawofre- the light in its paffage out ot the one into the other will fraction be refraCted towards or from the perpendicular, accord- when light ing as the refraCting forces of the fecond are greater or lefs than thofe of the firft, or rather according as the iparent bo-" area exprefling the fquare of the fpecific velocity isdyintoan- greater or lefs. And as the difference of thefe areas is other cen- a determined quantity, the difference between the velo- 10 city in the medium of incidence and the velocity in the11’ medium of refraCtion, will alfo be a determined quantity. Therefore the fine of the angle of incidence will be in a conitant ratio to the fine of the angle of refraction j and this ratio will be compounded of the ratio of the fine of incidence in the firft medium to the fine of re¬ fraCtion in a void; and the ratio of the fine of incidence in a void to the fine of refraCtion in the fecond medium. If therefore a ray of light, moving through a void in any direction, {hall pals through any number of media bounded by parallel planes, its direction in the laft me¬ dium will be the fame as if it had come into it from a void. Cor 5. It alfo follows from thefe propofitions, that if the obliquity of incidence on the pofterior furfaee of a tranfparent body be fuch, that the light fliould be reflected back again, the placing a mafs of the fame or of another medium in eontaCl with this furface, will caufe it to be tranfmitted, and this the more completely, as the added medium is more denfe or more refraCtive ^ and the reflection from the feparating furface will be the more vivid in proportion as the pofterior fubftance is lefs denfe or of a fmaller refraCtive power. It is not even neceffary that the other body be in contaCt; it is enough if it be fo near, that thofe parts of the refraCting ftrata which are beyond the bodies interfere with or co¬ incide with each other. All thefe confequences are agreeable to experience. The brilliant reflection from a dew-drop ceafes when it touches the leaf on which it refts ; The brilliancy of a diamond is greatly damaged by moifture getting be¬ hind it : The opacity of the combined mirror plates,, mentioned in Cor. 2. is removed by letting water get between them f A piece of glafs is diftinCtly or clearly feen in air, more faintly when immerfed in water, {till more faintly amidft oil of olives, and it is hardly per¬ ceived in fpirits of turpentine. Thefe phenomena are incompatible with the notion that reflection is occafioned by impaCt on folid matter, whether of the tranfparent body, or of any ether Or other fancied fluid behind it; and their perfeCt coincidence with the legitimate confe¬ quences of the affumed principles, is a ftrong argument in favour of the truth of thofe principles. It is worth while to mention here a faCt taken notice 0bjef- of by Mr Beguelin, and propofed as a great difficulty in tionto the the Newtonian theory 01 refraCtion. In order to get ^cwton|.aI1 the greateft p.offible refraCtion, and the fimpleft meafure of the refraCting power at the anterior furface of any tran{parent. Theory. . ' OPT Law of tranfparent fubflance, Sir Ifaac Newton enjoins us to Rciradhon employ a ray of light falling on the flit face quam obli- quiffimt. But Mr Beguelin found, that when the obli¬ quity of incidence in glafs was about 89° ^o', no light was refra&ed, but that it was wholly rededed. He al- fo observed, that when he gradually increafed the obli¬ quity of incidence on the polferior furface of the glafs, the light which emerged laid of all did not fltmi a- long the furface, making an angle of 9c0 with the per¬ pendicular, as it fliould do by the Newtonian theory, but made an angle of more than ten minutes with the pofterior furface. Alfo, when he began with very great obliquities, fo that all the light was refle&ed back into the glafs, and gradually diminiihed the obliquity of in¬ cidence, the firrt ray of light which emerged did not fkim along the furface, but was raifed about 10 or 15 minutes. Ill Shown to But all thefe phenomena are neceffary confequences of be the ne- our principles, combined with what obfervation teaches I ceflary ion- us concerning the forces which bodies exert on the rays oftlhtCe *s evident, from the experiments of Gri- 1 theory, and maldi and Newton, that light is both at traded and re- of courfe a pelled by folid bodies. Newton’s fagacious analyfis of con firm a- thefe experiments difeovered feveral alternations of ac¬ tion ot it. tuaj infection an(] defleftion 5 and he gives us the pre- cife diftance from the body when feme of thefe attrac¬ tions end and repulfion commences 5 and the moll re¬ mote a&ion to be obferved in his experiments is repul- fion. Let us fuppofe this to be the cafe, although it be Plate n0t abfoIutely nectary- Let us fuppofe that the forces cccLxxvii are represented by the ordinates of a curve a b npc fig, 7. which croffes the abfcilfa in b. Draw b 0 parallel to the refrading furface. When the obliquity of incidence of the ray AB has become fo great, that its path in the glafs, or in the refra&ing ilratum, does not cut, but on¬ ly touches the line 0 b, it can penetrate no further, but is totally refleded ; and this muft happen in all greater obliquities. On the other hand, when the ray LE, moving within the glafs, has but a very fmall perpendi¬ cular velocity, it will penetrate the refrading ftrafum no further than till this perpendicular velocity is extin- guifhed, and its path becomes parallel to the furface, and it will be refleded back. As the perpendicular ve¬ locity increafes by diminilhing the obliquity of incidence, it will penetrate farther ; and the laft refiedion will happen when it penetrates fo far that its path touches the line 0 b. Now diminilh the obliquity by a frngle fecond ; the light will get over the line 0 b, will de~ . feribe an arch 0 r/ B concave upwards, and will emerge in a diredion BA, which does not Hum the furface, but is fenfibly raifed above it. And thus the fads obferved by M. Beguelin, inflead of being an objedion againft this theory, afford an argument in its favour. Euler’s Cor. 6. Thofe philof >phers who maintain the theory lieory of of undulation, are under the neceflity of conneding the *on difperfive powers of bodies with their mean refradive ^rary to poWerS iru]er has attempted to deduce a neceffary difference in the velocity of the rays of different colours from the different frequency of the undulations, which he affigns as the caufe of their different colorific powers. His reafoning on this fubjed is of the molt delicate na¬ ture, and unintelligible to fuch as are not completely mailer of the infinitefimal calculus of partial differences, and is unfatisladory to fuch as are able to go through its intricacies. It is contradided by fad. He fays, ICS. 2II that mufical iounds which differ greatly in acutenefs are law of propagated through the air with different velocities : but Refradhon, one or the fmalieft bells in the chimes of St Giles’s v~“”— church in Edinburgh was ftruck againft the rim or the very deep-toned bell on which the hours are llruck. When tire found was lifu ned to by a nice obierver at the diftance of more than two miles, no interval what¬ ever could be obferved. A fimilar experiment was ex¬ hibited to M. Euler himfclf, by means of a curious in- ftrument ufed at St Peterftmrg, and which may be heard at three or four miles diftance. But the experi¬ ment with the bells is unexceptionable, as the two founds were produced in the very fame inftant. This connec¬ tion between the refrangibiiity in general and the velo¬ city muft be admitted, in its full extent, in every at¬ tempt to explain refradion by undulation ; and Euler was forced by it to adopt a certain confequence which made a neceffary connedion between the mean refrac¬ tion and the dilperfion of heterogeneous rays. Confident of his analyfis, he gave a deaf ear to all that was told him of Mr Dollond’s improvements on telefcopes, and afferted, that they could not be fuch as were related j for an increafe of mean refradion muff always be ac¬ companied with a determined increafe of difperfion. Newton had faid the fame thing, being milled by a li¬ mited view of his own principles \ but the difperfion af- figned by him was different from that afligned by Eu¬ ler. I he difpute betw’een Euler and Dollond was con¬ fined to the decifion of this queftion only ; and when fome glafies made by a German chemift at Peteifburg convinced Euler that his determination was erroneous, he did not give up the principle which had forced him to this determination of the difperfion, but immediately introduced a new theory of the achromatic telefcopes of Dollond ; a theory which took the artifts out of the track marked out by mathematicians, and in which they had made confiderable advances, and led them in¬ to another path, propofing maxims of conftrudlion hi¬ therto untried, and inconfiftent with real improvements which they had already made. The leading principle in and mil- this theory is to arrange the different ultimate images o£leacls a point which arife either from the errors of a fpherieal figure or different refrangibiiity, in a ftraight line paf- fing through the centre of the eye. The theory itfelf is fpecious ; and it requires great mathematical {kill to accomplifh this point, and hardly lefs to decide on the propriety of the conftru£Hon which it recommends. It is therefore but little known. But that it is a falfe theory, is evident from one fimple confideration. In the moft indiftinft vifion arifing from the worft con- ftrutftion, this redfilineal arrangement of the images ob¬ tains completely in that pencil which is fituated'in the axis, and yet the vifion is indiftimft. But, w hat is to our prefent purpofe, this new theory is purely mathema¬ tical, fulling any obferved difperfive power, and has no connedion with the phyfical theory of undulations, or indeed with any mechanical principles whatever. But, by admitting any difperfive power, whatever may be the mean refradion, all the phyfical dodrines in his Nova Theoria Lucis et Colorum are overlooked, and therefore never once mentioned, although the effeds of M. Zeiher’s glafs are taken notice of as inconfiftent with that mechanical propofition of Newton’s which occa- fioned the whole difpute between Euler and Dollond. They are indeed inconfiftent with the univerfality of D d 2 that 212 OPT Law of that proportion. "Newton advances it in his Optics Rein,(ftion. mereiy as a mathematical propofition highly probable, but fays that it will be corredled if he [hallfind it falfe. The ground on which he fieems (for he does not ex- prefsly fay fo) to reft its probability, is a limited view of his own principle, the aftion of bodies on light. He (not knowing any caufe to the contrary) fuppofed that the adlion of all bodies was fimilar on the different kinds of light, that is, that the fpecific velocities of the dif¬ ferently coloured rays had a determined proportion to each other. This was gratuitous; and it might have been doubted by him who had obferved the analogy be¬ tween the chemical aftions of bodies by eledlive attrac¬ tions and repulfions, and the fimilar actions on light. Not only have different menftrua unequal aflions on their folids, but the order of their affinities is alfo dif¬ ferent. In like manner, we might expect not only that fome bodies would attraft light in general more than others, but alfo might differ in the proportion of their aftions on the different kinds of light, and this fo much, that fome might even attraft the red more than the vio¬ let. The late difeoveries in chemiftry ffiow us fome very diftintl proofs, that light is not exempted from the laws of chemical aftion, and that it is fufceptible of chemical combination. The changes produced by the fun’s light on vegetable colours, (how the neceffity of illumination to produce the green fecula; and the aro¬ matic oils of plants, the irritability of their leaves by the adlion of light, the curious effedls of it on the mi¬ neral acids, on manganefe, and the calces of bifmuth and lead, and the imbibition and fubfequent emiffion of it by phofphorefcent bodies, are ftrong proofs of its che¬ mical affinities, and are quite inexplicable on the theory of undulations. All thefe confiderations taken together, had they been known to Sir Ifaac Newton, would have made him expedt differences quite anomalous in the difperfive powers of different tranfparent bodies •, at the fame time that they would have afforded to his fagacious mind the ftrongeft arguments for the actual emiffion of light from the luminous body. Having in this manner eftabliflied the obferved law of refradtion on mechanical principles, fhoAving it to be a neceffary confequence of the known adtion of bodies on light, we proceed to trace its mathematical confe- quences through the various cafes in which it may be exhibited to our obfervation. Thefe conftitute that part of the mathematical branch of optical fcience which is called dioptrics. The varia- We are quite unacquainted with the law of adtion of tion of the bodies on light, that is, with the variation of the inten- auradRonf ^ t^ie attra<^ons an^ repulfions exerted at different ancTrepul- diftances. All that we can fay is, that from the expe- fions un- riments and obfervations of Grimaldi, Newton, and known. others, light is defledted towards a body, or is attradled by it, at fome diftances, and repelled at others, and this with a variable intenfity. The adlion may be ex¬ tremely different, both in extent and force, in different bodies, and change by a very different law with the fame change of diftance. But, amidft all this variety, there is a certain fimilarity arifing from the joint adlion of many particles, which ffiould be noticed, becaufe it tends both to explain the fimilarity obferved in the re- i I c s. Part I. fradlions of light, and alfo its connexion with the phe- Law of nomena of refledlion. I'o.n a6hUm The law of variation in the joint adlion of many par- I20 tides adjoining to the furface of a refradting medium, is The law of extremely different from that of a fingle particle j but variation in when this laft is known, the other may be found out. ^ a?—RK : RP, =fin. DPR : fin. RKP, =rfin. DPR : fin. CPF. Therefore CPF is the angle of refradlion corre,ponding to the angle of incidence RPD, and PF is the refradted ray, and F the focus. £L E. D. Cor. 1. CK : CP=CR : CF, and CFr CPxC:R Plate ecclxxviii. %s- 5. 6> &.C. 1-8 The focus of ray_ re fracted by fpherical furlaces afeertained Now CP X CR is a confiant quantity ; and therefore CF is reciprocally as CK, which evidently varies with a va¬ riation of the arch VP. Hence it follows, that all the rays flowing from R are not colledled at the conjugate focus F. The ultimate fituation of the point F, as the point P gradually approaches to, and at laft coincides with, V, is called the conjugate focus of central rays, and the diflance between this focus and the focus of a lateral ray is called the aberration of that ray, arifing from the fpherieal figure. There are, however, two fituations of the point R fuch, that all the rays which flow from it are made to diverge from one point. One of thofe is C (fig. 5.), be- caufe they all pafs through without refradiion, and there¬ fore dill diverge from C ; the other is when rays in the rare medium with a convex furface flow from a point R, fo fituated beyond the centre that CV is to T C S. Pprt X. CR as the fine of incidence in the rare medium is to Pet on the fine of refradtion in the denier, or when rays in ''v ' ^i. the rare medium fall on the convex lurface of tht den- fer, converging to F, fo fituated that CF : CV — . ~ ^" j m : n. In this cafe they will all be difperft d trom F, fo fituated that CV : CF—« : m, — CR : CV for fire RPC : line PKC—« : m, — CR : CP, rriine RPC : fine PRC. Therefore the angle PRC is equal to PKC, or to FPC (by eonftrudtion of the problem), and the an^le C is common to the triangles PRC, FPC j they are therefor® fimdar and die angles PRC, FPC are equal, and n : CP: CF, = CK: CR,rrCR: CP j therefore CP: CK- CP1 : CR*: but CP and CR are confiant quantities, and therefore CK is a conftant quantity, and (by the corollary) CF is a conftant quantity, and. ail the rays flowing from R are difperfed from F by refradlion. In like manner rays converging to F will by refradlion con¬ verge to R. This was firft obferved by Huygens. Cor. 2. If the incident ray R’P is parallel to the axis Fig. 5. RC, we have PO to CO as the fine of incidence to the fine of refradlion. For the triangles R’PK’PCO are fi¬ milar, and PO : COrrR’K’ : R’P, —m : n. Cor. 3. In this cafe, too, we have the focal diftance of central parallel rays reckoned from the vertex — ~—X VC. For fince PO is ultimately VO, we have m—n J m : zzmVO : CO, and m—n : m—\0—CO : VO, — tn VC : VO, and YOzz x VC. This is called the. m—n principal focal diftance, or focal diftance of parallel rays. Alfo CO, the principal focal diliance reckoned from the centre, xVC. m—n N. B. When m is lefs than n, m—n is a negative quantity.—Alfo obferve, that in applying fymbols to this computation of the focal diftances, thofe lines are to be acceunted pofitive which lie from their begin¬ nings, that is, from the vertex, or the centre, or the radiant point, in the diredlion of the incident rays. Thus when rays diverge from R on the convex fur¬ face of a medium, VR is accounted negative and VC pofitive. If the light pafies out of air into glafs, m is greater than n ; but if it paffes out of glafs into air, m is lefs than n. If, therefore, parallel rays fall on the convex furface of glafs out of air, in which cafe m : «—3 : 2 very nearly, we have for the principal focal CK * diftance—— VC, or -f-3 VC. But if it pa& out of glafs into the convex furface of air, we have VO: -VC, or —2 VC ; that is, the focus O will be in the fame fide of the furface with the incident light. In like manner, we (hall have for thefe two cafes CO—4-2VC and —3 VC. Cor.4. Byconflrudlion we haveRK : RP—wz: n by fimilarity of triangles PF : RKrrCF : CR therefore PF: PR=rwCF:«CR and m PR X CFrrzz CR X PF therefore m PR : n CRrzPF : CF and m PR—/zCR : /zzPR—PF—CF: PF ultimately m VR—«CR : m VR=VC : VF This is a very general optical theorem, arAaffords an eafy method for computing the focal diftance of refraft* ed ravs. For Theory. OPT Retraction For this purpofe let VR, the diftance of the radiant by IsiiT" be exPreffed the fymbol r, the diftance of the Cfaces." focus of refrafted rays by the fymbol /, and the radius i t ■ of the fpherical furface by a ; we have m r-—« r—a : m r—a : f and mar mar -nrJ^n d In its application due attention muft be paid to the qualities of r and a, whether they be pofitive or nega¬ tive, according to the conditions of laft corollary. Plate Cor. 5. If be the focus of parallel rays coming ccclxxviii. from the oppofite fide, we (hall have RQ : £)C—RV : fig. S. VF. For draw C q parallel to PF, cutting RP in q ; then Vi. q \ q CrrRP : PF. Now q is the focus of the parallel rays EP, C y. And when the point P ultimate¬ ly coincides with the point V, q mult coincide with Q, and we have RQ^: Q^CrrRV : VF. This is the molt general optical theorem, and is equally applicable to lenfes, or even to a combination of them, as to fimple furfaces. It is alio applicable to refleiStions, with this difference, that is to be affumed the focus of parallel rays coming the fame way with the incident rays. It affords us the molt compendious me¬ thods of computing fymbolically and arithmetically the focal diltances in all cafes. Cor. 6. We have alfo Ry : RPrrRV : RF, and ulti¬ mately for central rays R£) : RVr=RV : RF, and RF= RV* This propofition is true in lenfes and mirrors, but not in fingle refracting furfaces. Cor. 7. AlfoRy: RC—RP : RF, and ultimately R£) : RV=RC : RF, and RFzrRVD*RC. N. B. Thefe four . . . points £), V, C, F, either lie all one way from P, or two of them forward and two backward. Cor. 8. Alio making O the principal focus of rays coming the fame way, we have R y : y C=rC 0 : oF, and ultimately RQ, : O : OF, and OF=^^-~9> and therefore reciprocally proportional to R£), becaufe &cx™ is a conltant quantity. Thefe corollaries or theorems give us a variety of Uaethods for finding the focus of refraCted rays, or the other points related to them ; and each formula contains four points, of which any three being given, the fourth ' may be found. Perhaps the laft is the molt fimple, as the quantity oc-f-c Q is always negative, becaufe 0 and Q are on different lides. Cor. 9. From this conltruCtion we may alfo derive a Very eafy and expeditious method of drawing many re- fraCted rays. Draw through the centre C (fig. 15. 16.) a line to the point of incidence P, and a line CA pa¬ rallel to the incident ray RP. Take VO to VC as the fine of incidence to the fine of refraCtion, and about A, with the radius VO, deferibe an arch of a circle cutting PC produced in B. Join AB : and PF parallel to AB is the refrafted ray. When the in¬ cident light is parallel to RC, the point A coincides with V, and a circle deferibed round V with the di- ftance VO will cut the lines PC, p C, Stc. in the points BZ». The demonftration is evident. Having thus determined the focal diftanee of re- fra&ed rays, it will be proper to point out a little 3 ICS. 215 more particularly its relation to its conjugate focus of Refmtftion incident rays. We fhall confider the four cafes of light -pheri- incident on the convex or concave furface of a denier Cf1 Sur' or a rarer medium, « 1. Let light moving in air fall on the convex Fig. 5. to furface of glafs. Let us fuppofe it tending to a point %• beyond the glafs infinitely diftant. It tvill be collect¬ ed to its principal focus 0 beyond the vertex V. Now let the incident light converge a little, fo that R is at a great dillance beyond the furface. The focus of refra&ed rays F will be a litJe within O or nearer to V. As the incident rays are made to converge more and more, the point R comes nearer to V, and the point F alfo approaches it, but with a much flower motion, being always fituated between O and C till it is overtaken by R at the centre C, when the incident light is perpendicular to the furface in every point, and therefore fuffers no refradlion. As R has overtaken F at C, it now paffes it, and is again overtaken by it at V. Now the point R is on the fide from which the light comes, that is, the rays diverge from R. After refraclion they will diverge from I a little without R j and as R recedes farther from V, F recedes ftill farther, and with an accelerated motion, till, when R comes to £), F has gone to an infinite diftance, or the refrafted rays are parallel. When R ftill recedes, F now appears on the other fide, or beyond V ; and as R recedes back to an in¬ finite diftanee, F has come to O : and this completes the feries of variations, the motion of F during the whole changes of fituation being in the fame direction with the motion of R. 2. Let the light moving in air fall on the concave furface of glafs 5 and let us begin with parallel inci¬ dent rays, conceiving, as before, R to lie beyond the glafs at an infinite diftance. The refradled rays will move as if they came from the principal focus O, lying on that fide of the glafs from which the light comes,, As the incident rays are made gradually more conver¬ ging, and the point of convergence R comes toward the glafs, the conjugate focus F moves backward from O $ the refra£led rays growing lefs and lefs di¬ verging, till the point R comes to ^), the principal focus on the other fide. The refrafted rays growing parallel, or F has retreated to an infinite diftance. The incident light converging ftill more, or R coming between £) and V, F will appear on the other fide, or beyond the furface, or within the glafs, and will ap¬ proach it with a retarded motion, and finally overtake R at the furface of the glafs. Let R continue its mo¬ tion backwards (for it has all the while been moving backwards, or in a direftion contrary to that of the light) ; that is, let R now be a radiant point, moving backwards from the furface of the glafs. F will at firft be without it. but will be overtaken by it at the centre C, when the rays will fuffer no refra£Hon. R ftill receding will get without F 5 and while R recedes to an infinite diftance, F will recede to O, and the feries will be completed. 3. Let the light moving in glafs fall on the convex furface of air ; that is, let it come out of the concave furface of glals, and let the incident rays be parallel, or tending to R, infinitely diftant: they will be dif- perfed by refra&ion from '•he prinoipal focus O with¬ in the glafs. As they are made more converging, R cornea- 2t6 OPT On Lenfip*. comes nearer, and F retreats backward, till R comes to £), the principal focus without the glafs $ when F is now at an infinite diftance within the glafs, and the re¬ fracted rays are parallel. R Rill coming nearer, F now appears before the glafs, overtakes R at the centre C, and is again overtaken by it at N. R now becoming a radiant point within the glafs, F follows it backwards, and arrives at O, when R has receded to an infinite diftance, and the feries is completed. 4. Let the incident light, moving in glafs, fall on the concave furface of air, or come out of the convex furface of glafs. Let it tend to a point R at an infinite diftance without the glafs. The refraCled rays will converge to O, the principal focus without the glafs. As the inci¬ dent light is made more converging, R comes towards the glafs, while F, fetting out from v, alfo approaches the glafs, and R overtakes it at the furface V. R now becomes a radiant point within the glafs, receding back¬ wards from the furface. F recedes flower at firft, but overtakes R at the centre C, and paffes it with an ac¬ celerated motion to an infinite diftance 5 while R re¬ treats to £), the principal focus within the glafs. R ftill retreating, F appears before the glafs ; and while R re¬ treats to an infinite diftance, F comes to V, and the fe¬ ries is completed. Sect. IV. On Len/es* I29 Xenfes, Lenfes for optical purpofes may be ground into nine how many, different fhapes. Lenfes cut into five of thofe ftiapes, together with their axes, are deferibed in vol. vi. page Plate 33* (See Dioptics). The other four are, ccclxxix. !• A plane gla/sy which is flat on both hides, and of igs. i. 2. equal thicknefs in all its parts, as EF, fig. 1. 2. A J?ctt plano-convex, whofe convex fide is ground into feveral little flat furfaces as A, fig. 2. 3. A prifm, which has three flat fides, and wrhen viewed end wife appears like an equilateral triangle, as B. 4. A concavo-convex glafs, or tnenifeus, as C, which Ylg r is feldom made ufe of in optical inftruments. A ray of light Gh falling perpendicularly on a plane glafs EF, will pafs through the glafs in the fame direc¬ tion hi, and go out of it into the air in the fame ftraight line iH. A ray of light AB falling obliquely on a plane glafs, will go out of the glafs in the fame direction, but not in the fame ftraight line: for in touching the glafs, it will be refracted in the line BC ; and in leav¬ ing the glafs, it will be refracted in the Une CD. Lemma. Fig. 3. to 6. There is a certain point E within every double convex or double concave lens, through which every ray that pafies will have its incident and emergent parts QA, a q parallel to each other : but in a plano-convex or plano-concave lens, that point E is removed to the vertex of the concave or convex furface; and in a menifeus, and in that other concavo-convex lens, it is removed a little way out of them, and lies next to the fur¬ face which has the greateft curvature. For let REr be the axis of the lens joining the cen¬ tres B, r of its furfaces A, a. Draw any two of their ICS. Part ]. femidiameters R A, ra parallel to each other, and join Lenfe. the point, A, a, and the line A a will cut the axis in ” the point E above dtferihed. For the triangles REA, rEr being equiangular, RE will be to Er in the given ratio of the femidiameters RA, ra; and confequently the point E is invariable in the fame lens. Now lup- poiing a ray to pafs both ways along the line A a, it being equally inclined to the perpendiculars to the lurtaces, will be equally bent, and contrariwife in go¬ ing out of the lens 5 fo that its emergent part AQ^ aq will be parallel. Now any of thefe lenles will be¬ come plano-convex or plano-concave, by conceiving one of the femidiameters RA, ra to become infinite, and confequently to become parallel to the axis of the lens, and then the other femidiameter will coincide with the axis 5 and fo the points A, E or «, E will coincide. E. D. Corol. Hence when a pencil of rays falls almoft per¬ pendicularly upon any lens, whofe thicknefs is incon- fiderable, the courfe of the ray which paffes through E, above deferibed, may be taken for a ftraight line paffing through the centre of the lens without fen- fible error in fenfible things. For it is manifeft from the length of A a, and from the quantity of the refrac¬ tions at its extremities, that the perpendicular diftance of A£), aq, when produced, will be diminifhed both as the thicknefs of the lens and the obliquity of the ray is diminifhed. Prop. I. To find the focus of parallel rays falling almoft perpendicularly upon any given lens. Let E be the centre of the lens, and r the centres of Fig. 7. te its furfaces, R r its axis, g EG a line parallel to the inci- I3* dent rays Upon the furface B, whofe centre is R. Paral- Yheiocm lei to^E draw a femidiameter BR, in which produced 0f paraiiej let V be the focus of the rays after their firft refraftion rays falling at the furface B, and joining Vr let it cut E produced perpendicuJ in G, and G will be the focus of the rays that emerge J from the lens. ^ For fince V is alfo the focus of the rays incident upon the fecond furface A, the emergent rays imift have their focus in fome point of that ray which paffes ftraight through this furface j that is, in the line Vr, drawn through its centre r .* and fince the whole courfe of another ray is reckoned a ftraight line g EG f, its f Corol. mterfeftion G with V r determines the focus of them *rom all. 4- E- D* ma' Corol. i. When the incident rays are parallel to the axis rR, the focal diftance EF is equal to EG. For let the incident rays that were parallel to ^ E be gra¬ dually more inclined to the axis till they become paral¬ lel to it j and their firft and fecond foci V and G will deferibe circular arches NT and GF whofe centres are R and E. For the line RV is invariable ; being in proportion to RB in a given ratio of the leffer of the fines of incidence and refraftion to their difference (by a former propofition) •, confequently the line EG is alfo invariable, being in proportion to the given line RV in the given ratio of rE to rR, becaufe the triangles EGr, RVr are equiangular. Corol. 2. The laft proportion gives the following rule for finding the focal diftance of any thin lens. As Rr, the interval between the centres of the furfaces. Theory. OPT Of Lenfe-^ is to /•£, the feraldlaffieter of the fecond furface, fp is y "J RV °r E 1, the continuation of the firlt iemidiameter to the firlt focus, to EG or EF the focal diftance of the lens ; which, according as the lens is thicker or thinner in the middle than at its edges, muft lie on the fame fide as the emergent rays, or on the oppofite fide. Corol. 3. Hence when rays fall parallel on both fides of any lens, the focal difiances EF, E/are equal. For let ri be the continuation of the femidiameter E r to the firft focus t of rays falling parallel upon the furface A ; and the fame rule that gave rR • rE= RT : EF, gives alfo rR : REzrr/■ : Ef. Whence E/=: EF, becaufe the re&angles/-Ex BT:=RE X rFor r E is to r r and alfo RE to RT in the fame given ratio, Corol. 4, Hence in particular in a double convex or double concave lens made of glafs, it is as the furii of their femidiameters (or in a menifeus as their difference) to either of them, fo is double the other, to the focal diftance of the glafs. For the continuations RT, /• t are feverally double their femidiameters : becaufe in glafs ET : TR and alfo E/ : ^/~3 : 2. Corol. 5. Hence if the femidiameters of the furfaces of the glafs be equal, its focal diftance is equal to one of them j and is equal to the focal diftance of a piano-con- vex or plano-concave glafs whofe femidiameter is as fhort again. For confidering the plane furface as having an infinite femidiameter, the firft; ratio of the laft-mention- cd proportion may be reckoned a ratio of equality. Prop. II. The foous The focus of incident rays upon a fingle furface, raysTundf fPhefe» or lensi being given, it is required to find the focus of the emergent rays. Plate ccclxxx. fig. I. to 6 * By Co. rol. from former Prep. • Let any point be the focus of incident rays upon a fpherical furface, lens, or fphere, whofe centre is E ; and let other rays come parallel to the line QE q the contrary way to the given rays, and after refra&ion let them belong to a focus F; then taking E/equal to EF the lens or fphere, but equal to FC in the fingle furface, fay as QF to FE fo Ef tofq; and placing^ the con¬ trary way from f to that of E(f from F, the point q will be the focus of the refra&ed rays, without fenfible error j provided the point £) be not fo remote from the axis, nor the furfaces fo broad, as to caufe any of the rays to fall too obliquely upon them. For with the centre E and femidiameters EF and E/defcribe two arches FG,/g cutting any ray QA«y in G and g, and dravv EG and E^. Then fuppofmg G to be a focus of incident rays (as GA), the emer¬ gent rays (as ag y) will be parallel to GE * ; and on the other hand fuppofing g another focus of incident rays (as gn), the emergent rays (as AG^)) will be pa¬ rallel to^E. Therefore the triangles ()GE, Egq are equiangular, and confequently QG : GErrE^- gq; that is, when the ray QAtfy is the neareft to QeV £VF -.EE—Ef-.fg. Now when £) accedes to F and' coincides with it, the emergent rays become parallel, that is, q recedes to an infinite diftance j and confe¬ quently when f) paffes to the other fide of F, the fo¬ cus q will alfo pafs through an infinite fpace from one fide of/to the other fide of it. O. E. D Vox, XV. Part I. ics. 2r? Corol. i. In a fphere or lens the focus q may be OfLenfes, found by this rule: QF : QE=QE : Qy, to be" Y—*-? placed the fame way from Q as QF lies" from Q.—. For let the incident and emergent rays QA, y a bejiro- duced till they meet in e; and the triangles QGE, Qey being equiangular, we have QG : QE=Q a is equiangular at the bafe A a, and confequently A e and ae will at laft become femdiameters of the fphere. In a lens the thicknefs A a is inconfiderable. The focus may alfo be found by this rule : QF ; FE=QE : Ey, for QG : GE=QA : A y!- And then the rule formerly demonftrated for fingle fur¬ faces holds good for the lenfes. Corol. 2. In all cafes the diftance^/y varies recipro¬ cally as FQ does 5 and they lie contrariwife from f and F; becaufe the reftangle or the fquare under EF and E^f the middle terms in the foregoing proportions, is invariable. The principal focal diftance of a lens may not only be found by collefting the rays coming from the fun, confidered as parallel, but alfo (by means of this pro- pofition) it may be found by the light of a candle or window. For, becaufe Qy : yA=QE : EG, w'e have (when A coincides with E) p y : yErrGE : EF 5 that is, the diftance obferved between thtTra¬ diant objedft and its pi£ture in the focus is to the di¬ ftance of the lens from the focus as the diftance of the lens from the radiant is to its principal focal di¬ ftance. Multiply therefore the diftances of the lens from the radiant and focus, and divide the produft by their Him. Corol. 3. Convex lenfes of different lhapes that have equal focal diftance when put into each others places, have equal powers upon any pencil of rays to refraft them to the fame focus. Becaufe the rules above mentioned depend only upon the focal diftance of the lens, and not upon the proportion of the femidiameters of its furfaces. Corol. 4. The rule that was given for a fphere of an uniform denfity, will ferve alfo for finding the focus of a pencil of rays refra&ed through any number of con¬ centric furfaces, which feparate uniform mediums of any different denfities. For when rays come parallel to any line drawn through the common centre of thefe me¬ diums, and are refrafted through them all, the diftance of their focus from that centre is invariable, as in an uniform fphere. Corol. 5. When the focufes Q, y lie on the fame fide of the refra&ing furfaces, if the incident rays flow from Q, the refracted rays will alfo flow from y; and if the incident rays flow towards Q, the refracted will alfo flow towards y; and the contrary will happen when Q and y are on contrary fides of the refradting furfaces. Becaufe the rays are continually going forwards. From this propofition we alfo derive an eafy method of drawing the progrefs of rays through any number of lenfes ranged on a common axis. Let A, B, C, be the lenfes, and R A a ray incident Fig. «, on the firft of them. Let *, *, be their foci for pa- rallel rays coming in the oppofite diredtion ; draw the perpendicular a d, cutting the incident ray in d, and draw d a through the centre of the lens : AB parallel E e 2 I 8 Of Vi«on. o p T I c S. Part I, to da Avill be the ray refrafted by the firft lens. ' v' Through the focus of the fecund lens draw the perpen¬ dicular /3 e, cutting AB in e; and draw eb through the centre of the fecund lens. BD parallel to b c will be the next refracted ray. Through the focus x of the third lens draw the perpendicular x.f cutting BD in f, and draw f c through the centre of the third lens. CE parallel to/c, will be the refradted ray *, and fo on. Sect. V. On Vijion, Having defcribed how the rays of light, flowing from objedts, and paffing through convex glaffes, are colledl- ed into points, and form the images of external objedts; it will be eafy to underftand how the rays are refradted by the humours of the eye, and are thereby colledled into innumerable points on the retina, on which they form the images of the objedls from which they flow. For the different humours of the eye, and particularly the cryftalline, are to be confidered as a convex glafs ; and the rays in palling through them as aftedled in the fame manner in the one as in the other. A defcription of the coats and humours, &c. has been given in Ana¬ tomy •, but it will be proper to repeat as much of the defcription as will be fufficient for our prefent pur- pofe. Plate The eye is nearly globular, and confiftsof three coats CCCLXXX and three humours. The part DHHG of the outer fig. 8. coat, is called thefc/erotica; the reft, DEFG, the cornea. Defcnption Next within this coat is that called the choroides, which of the eye. ferves as it were for a lining to the other, and joins with the iris, ?nn,7nn. The iris is compofed of two fets of mufcular fibres j the one of a circular form, which contracts the hole in the middle called the pupil, when the light would other wife be too ftrongfor theeye; and the other of radical fibres, tending everywhere from the circumference of the iris towards the middle of the pupil ; which fibres, by their contradlion, dilate and enlarge the pupil when the light is weak, in order to let in a greater quantity of it. The third coat is only a fine expanfion of the optic nerve L, which fpreads like net work all over the infide of the choroides, and is therefore called the retina; upon which are thrown the images of all vifible objects. Under the cornea is a fine tranfparent fluid like water, thence called the aqueous humour. It gives a protube¬ rant figure to the cornea, fills the two cavities m m and n n, which communicate by the pupil P ; and has the fame limpidity, fpecific gravity, and refrafting power, as water. At the back of this lies the cryftalline hu¬ mour II, which is lhaped like a double convex glafs; and is a little more convex on the back than the fore part. It converges the rays, which pafs through it from every vifible objeft to its focus at the bottom of the eye. This humour is tranfparent like cryftal, is of the confidence of hard icily, and is to the fpecific gravity of water as 11 to 10. It is enclofed in a fine tranfparent membrane, called the capfule of the cryftalline lens, from which proceed radial fibres o o, called the ciliary ligaments, all around its edge, and join to the circum¬ ference of the iris. At the back of the cryftalline, lies the vitreous hu¬ mour KK, which is tranfparent like glafs, and is largeft of all in quantity, filling the whole orb of the eye, and giving it a globular fnape. It is much of a confiftence Of Vifion. with the white of an egg, and very little exceeds the fpecific gravity and refractive power of water. ^ As every point of an object ABC, fends out rays in The objefts all directions, fume rays, from every point on the fide on the reti- next the eye, will fall upon the cornea between E. andna °Dhe F; and by paffing on through the pupil and humours of m' the eye, they will be converged to as many points on the retina or bottom of the eye, and will form upon it a diltindt inverted picture c ba, of the object. Thus, the Fig. 8. pencil of rays qrs that flows from the point A of the objedt, will be converged to the point a on the retina; thofe from the point B will be converged to the point b; thofe from the point C will be converged to the point c; and fo of all the intermediate points : by which means the whole image a b c is formed, and the objedl made vifible; though it muft be owned, that the me¬ thod by which this fenfation is conveyed by the optic nerve from the eye to the brain, and there difeerned, is above the reach of our comprehenfion. That vifion is effedled in this manner, may be de- monftrated experimentally. Take a bullock’s eye whilft it is freflr; and having cut off the three coats from the back part, quite to the vitreous humour, put a piece of white paper over that part, and hold the eye to¬ wards any bright objedl, and you will fee an inverted pidlure of the objedl upon the paper, or the fame thing > may be better accompliffied by paring the fclerotic coat fo thin that it becomes a little tranfparent, and retains the vitreous humour. ^ Since the image is inverted, many have wondered whv they why the objedl appears upright. But tve are to confider, are feen up- l. That inverted is only a relative term: and, 2. Thaf'g^* there is a very great difference between the real objedl and the image by which we perceive it. When all the parts of a diftant profpedl are painted upon the retina, they are all right with refpedl to one another, as well as the parts of the profpedl itfelf; and we can only judge of an objedl’s being inverted, when it is turned reverfe to its natural pofition with refpedl to other objedls which we fee and compare it with.—If we lay hold of an upright ftick in the dark, we can tell which is the upper or lower part of it, by moving our hand downward or upward; and know very well that we can¬ not feel the upper end by moving pur hand downward. Tn the fame manner we find by experience, that upon diredling our eyes towards a tall objedl, we cannot fee its top by turning our eyes downward, nor its foot by turning our eyes upward ; but muft trace the objedl the fame way by the eye to fee it from head to foot, as we do by the hand to feci it ; and as the judgment is in¬ formed by the motion of the hand in one cafe, fo it is alfo by the motion of the eye in the other. In fig. 9. is exhibited the manner of feeing the fame Fig. 9. objedl ABC, by both the eyes D and E at once. ^ When any part of the image cb a falls upon the op-An objeft tic nerve L, the correfponding part of the objedl be-when view- comps invifible. On this account, the optic nerve wifely placed, not in the middle of the bottom of the 'j^s eye, but towards the fide next the nofe ; fo that what-peardouble, ever part of the image falls upon the optic nerve of onebecaufe eye, may not fall upon the optic nerve of the other, d16 °Pilc. Thus the point a of the image cb a falls upon the optic 0; nerve of the eye D, but not of the eye E; and the point ment Fig. 2 Theory. OPT Of Vifion. c falls upon tlie optic nerve of tire eye E, but not of the -v 1 eye D j and therefore to both eyes taken together, the whole object ABC is vifible. The nearer that any object is to the eye, the larger is the angle under which it is feen, and the magnitude of which it appears. Thus to the eye D, the" object ABC is feen under the angle APC 5 and its image cba Plate j3 Very large upon the retina : but to the eye E, at a ccclxxxi. diftance, the fame objeft is feen under the angle S‘ ' ApC, which is equal only to half the angle APC, as is evident by the figure. The image c b a is like wife twice as large in the eye D, as the other image c £ <7 is in the eye E. In both thefe reprefentations, a part of the image falls on the optic nerve, and the object in the correfponding parts is invifible. As the fenfe of feeing is allowed to be occafioned by the impylfe of the rays from the vifible objeft upon the retina, and thus forming the image of the objeft upon it, and that the retina is only the expanfion of the optic nerve all over the choroides •, it fiiould feem furprifing, that the part of the image which falls on the optic nerve Ihould render the like part of the object in¬ vifible ; efpecially as that nerve is allowed to be the inftrument by which the impulfe and image are convey¬ ed to the common fenfory in the brain. 13$ That part of the image which falls upon the middle Proved by of the optic nerve is loit, and confequently the corre- expen- fponding part of the objeft is rendered invifible, is plain by experiment. For if a perfon fixes three patches, A, B, C, (fig. 2.) upon a white wall, at the height of the eye, and at the diftance of about a foot from each other, and places himfelf before them, ftmtting the right eye, and direding the left towards the patch C, he will fee the patches A and C, but the middle patch B will difappear. Or, if he fhuts his left eye, and direds the right towards A, he will fee both A and C, but B will difappear ; and if he direds his eye towards B, he will fee both B and A, but not C. For whatever patch is di- redly oppofite to the optic nerve N, vanithes. This re¬ quires a little pradice 3 after which he will find it eafy to dired his eye fo as to lofe the fight of whatever patch he pleafes. r This experiment, firft tried by M. Marriotte, occa- conceming fioned a new hypothefis concerning the feat of vifion, vifionat 0t fapp0^ not to be in the retina, but in the choroides. An improvement on the experiment was af¬ terwards made by M. Picard, who contrived that an objed ftiould difappear when both the eyes were kept open. He faftened upop a wall a round white paper, an inch or two in diameter *, and by the fide of it he fixed two marks, one on the right hand, and the other on the left, each at about two feet diftance from the paper, and fomewhat higher. He then placed himfelf diredly be¬ fore the paper, at the diftance of nine or ten feet, and putting the end of his finger over againft both his eyes, fo that the left-hand mark might be hid from the right eye, and the right-hand mark from the left eye. Re¬ maining firm in this pofture, and looking fteadily, with both eyes, on the end of his finger, the paper which was not at all covered by it would totally difappear. 1 his, he fays, is the more furprifing, becaufe, without this particular encounter of the optic nerves, where no vifion is made, the paper will appear double, as is the cafe when the finger is not rightly placed. I c 219 . 'V Difpute M. Marriotte obferves, that this improvement on his Of Vifion. experiment, by M. Picard, is ingenious, but difficult to »r~““ execute, fince the eyes muft be confiderably ftrained in looking at any objeeft fo near as four inches ; and pro- pofes another not lefs furprifing, and more eafy. Place, fays he, on a dark ground, two round pieces of white paper, at the iame height, and three feet from one an¬ other 3 then Itand oppofite to them, at the diftance of 1 2 or 13 feet, and hold your thumb before your eyes; at the diftance of about eight inches, fo that it may conceal from the right eye the paper that is to the left hand, and from the left eye the paper to the right hand. Then, if you look at your thumb fteadily with both eyes, you will lofe fight of both the papers ; the eyes being to diipofed, that each of them receives the image of one of the papers upon the bafe of the optic nerve, while the other is intercepted by the thumb. M. Le Cat purfued this curious experiment a little farther than M. Marriotte. In the place of the fccond paper, he fixed a large white board, and obferved, that at a proper diftance he loft fight of -a circular fpace in the centre of it. He alfo obferved the fize of the paper which is thus concealed from the fight, correfpond¬ ing to feveral diftances, which enabled him to aicertain feveral circumftances relating to this part of the ftructure of the eye more exactly than had been done before. I he following is the manner in which this curious experiment is now generally made. Let three pieces of paper be faftened upon the fide of a room, about two feet afunder ; and let a perfon place himfelf oppofite to the middle paper, and, beginning near to it, retire gradually backwards, all the while keeping one of his eyes thut, and the other turned obliquely towards that outfide paper which is towards the covered eye, and he will find a fituation (which is generally at about five times the diftance at which the papers are placed from one another), when the middle paper Avill entirely dif¬ appear, while the two outermoft continue plainly vi¬ fible 3 becaufe the rays which come from the middle paper will fall upon the retina where the optic nerve is inferted. It is not furprifing that M. Marriotte was led, by this remarkable obfervation, to fufpedt that the retina was the feat of vifion. He not only did fo ; but, in confe- quence of attentively confidering the fubjefl, a variety of other arguments in favour of the choroides occurred to him, particularly his obfervation, that the retina is tranfparent, as well as the cryftalline and other humours of the eye, which he thought could onlyT enable it to tranfmit the rays farther ; and he could not perfuade himfelf that any fubftance could be confidered as being the termination of the pencils and the proper feat of vi¬ fion, at which the rays are not flopped in their progrefs. He was farther confirmed in his opinion of the fmall degree of fenfibility in the retina, and of the greater fenfibility of the choroides, by obferving that the pupil dilates itfelf in the (hade, and contrafts itfelf in a great light; which involuntary motion, he thought, was a clear proof that the fibres of the iris are extremely fenfible to the aftion of light; and this part of the eye is only a continuation of the choroides. He alfo thought that the dark colour of the choroid coat was ' intended to make it more fufceptible 6f the impreffion of light. Ee 2 M.- 220 OPT OfVifion. M. Pecquet, in anfvver to M. Mamotte’s obfervation ' concerning the tranfparency of the retina, fays, that it is very imperfectly fo, refembling only oiled paper, or the horn that is ufed for lanterns ; and befides, that its ■\vhitenefs demonftrates it to be fufficiently opaque for Hopping the rays of light, as much as is neceffary for the purpofe of vilion ; whereas, if vifion be performed by means of thofe rays which are tranfmitted through fuch a fubftance as the retina, it muft be very indiftindt. The retina refembles very much the thin white film which intervenes between the white of an egg and its fhell. As to the blacknefsof the choroides, which M. Mar- riotte thought to be neceflary for the purpofe of vifion, M. Pecquet obferves, that it is not the fame in all eyes, and that there are very different Ibades of it among the individuals of mankind, as alfo among birds, and fome other animals, whofe choroides is generally black $ and that in the eyes of lions, camels, bears, oxen, Hags, fheep, dogs, cats, and many other animals, that part of the choroides which is the moft expofed to light, very often exhibits colours as vivid as thofe of mother-of- pearl, or of the iris. He admits that there is a defedt of vifion at the inferlion of the optic nerve ; but he thought that it was owing to the blood-velfels of the retina, the trunks of which are fo large in that place as to obftrudt all vifion. To M. Pecquet’s objedtion, founded on the opacity of the retina, M. Marnotte replies, that there mull be a great difference betwixt the Hate of that fubflance in living and dead fubjedts j and as a further proof of . the tranfparency of the retina, and the power of the choroides beyond it to refiedt light, he fays, that if a lighted candle be held near to a perfon’s eyes, and a dog, at the diftance of eight or ten Heps, be made to look at him, he would fee a bright light in the dog’s eyes, which he thought to proceed from the refledtion of the light of the candle from the choroides of the dog, fince the fame appearance cannot be produced in the eyes of men, or other animals, whofe choroides is black. M. Marriotte obferves, in oppofition to Pecquet’s re¬ mark concerning the blood-veffels of the retina, that they are not large enough to prevent vifion in every part of the bafe of the nerve, fince the diameter of each of the two velfels occupies no more than ^th part of it. Befides, if this were the caufe of this want of vifion, it would vanilh gradually, and the fpace to which it is confined would not be fo exadlly terminated as it appears to be. We muft add, that M. Pecquet alfo obferved, that notwithftanding the infenfibility of the retina at the in- fertion of the optic nerve when the light is only mode¬ rate j yet luminous objedls, fuch as a bright candle pla¬ ced at the diftance of four or five paces, do not abfo- lutely difappear, in the fame circumftances in which a white paper would •, for this ftrong light may be per¬ ceived though the pidture fall on the bafe of the nerve. Hr Prieftley, however, found that a large candle made no impreffion on that part of his eye, though by no means able to bear a ftrong light. The common opinion was alfo favoured by the ana¬ tomical defcription of feveral animals by the members cf the French academy, and particularly their account of the fea calf and porcupine j in both of which the optic nerve is inferted in the very axis of the eye, ex- I C S. Parti. adlly oppofite to the pupil, which was thought to leave OfVifion. no room to doubt, but that in thefe animals the retina ''“'"‘v——' is perfedtly fenfible to the imprelfion of light at the in- fertion of the nerve. M. He la Hire took part with M. Pecquet, arguing in favour of the retina from the analogy of the lenfes, in all of which the nerves are the proper feat of fenfa- tion. This philofopher, however, fuppofed that the cho¬ roid coat receives the imprelfions of images, in order to tranfmit them to the retina. M. Perrault alfo took the part of M. Pecquet againft M. Marriotte, and in M. Perrault’s works we have fe¬ veral letters that pafl'ed between thefe two gentlemen upon this fubjedt. This difpute was revived by an experiment of M. Mery, recorded in the memoirs of the French Acade¬ my for 1704. He plunged a cat in water, and expofing her eye to the ftrong light of the fun, obferved that the pupil was not at all contradted by it j whence he con¬ cluded, that the contradtion of the iris is not produced by the adtion of the light. For he contended that the eye receives more light in this lituation than in the open air. At the fame time he thought he obferved that the retina of the cat’s eye was tranfparent, and that he could fee the opaque choroides beyond it: from which he concludes, that the choroides is the fubftance intend¬ ed to receive the rays of light, and to be the chief in- ftrument of vifion. But M. He la Hire, in oppofition to this argument of M. Mery, endeavours to fliow that fewer rays enter the eye under water, and that in thofe circumfiances it is not fo liable to be affedled by them. Befides, it is obvious, that the cat muft be in great terror in this fituation ; and being an animal that has a very great voluntary power over the mufcles of the iris, and being now extremely attentive to every thing about her, the might keep her eye open notwith¬ ftanding the adlion of the light upon it, and though it might be very painful to her. We are informed, that when a cat is placed in a window through which the fun is thining, and confequently her iris nearly clofed, if {he hear a ruftling, like that which is made by a moufe, on the outfide of the window, ftie will immedi¬ ately open her eyes to their greateft extent, without in the leaft turning her face from the light. M. Le Cat took the fide of M. Marriotte in this con- troverfy, it being peculiarly agreeable to his general hy- pothefis, viz. that the pia mater, of which the choroides is a produdtion, and not the nerves themfelves, is the proper inftrument of fenfation. He thought that the change which takes place in the eyes of old people (the choroides growing lefs black with age) favoured his hy- pothefis, as they do not fee with the fame diftindtnefs as young perfons. M. Le Cat fuppofed that the retina anfwers a purpofe fimilar to that of the fcarf-lkin, cover¬ ing the papillae pyramidales, which are the immediate organs of feeling, or that of the porous membrane which covers the glandulous papillae of the tongue. The re¬ tina, lie fays, receives the impreffion of light, moderates it, and prepares it for its proper organ, but is not itfelf fenfible of it. It muft be obferved, that M. Le Cat had difeovered that the pia mater, after clofely embracing the optic nerve, at its entrance into the eye, divides into two- branches, one of which clofely lines the cornea, and at length is loft in it, while the fecond branch forms what. is. Theory. OPT Of Vifion. is called the choroides, or uvea. He alfo fhowed that v-^\ 1 the fclerotic coat is an expanfion of the dura mater: and he fent diffeftions of the eye to the Royal Academy of Sciences in 1739, to prove thefe affertions, and feve- ral others contrary to the opinions of the celebrated Window, which he had advanced in his Traitd de Sens. •To thefe arguments in favour of the choroides, we may add the following given by Mr MicheJl. In order that vifion be difi.in£t, the pencils of rays which ifl'ue from the feveral points of any objeft, mu ft be colleffed either accurately, or at leaft very nearly, to correfponding points in the eye, which can only be done upon feme uniform furface. But the retina being of a confiderable thicknefs, and the whole of it being uni¬ formly nervous, and at leaft nearly, if not perfedlly, tranfparent, prefents no particular furface 5 fo that, in whatever part of it the pencils be fuppofed to have their foci, the rays belonging to them will be feparated from one another, either before or after they arrive there, and confequently vifion would be confufed. If we fuppoie the feat of vifion to be at the interior furface of the retina, and the images of objects to be formed by diretft rays, a confiderable degree of confu- fion could not but arife from the light refie6!ed by the choroides, in thofe animals in which it is white, or co¬ loured. On the other hand, it would be impoflible that vifion ftiould be performed at this place by light refietft- ed from the choroides, becaufe in many animals it is perfe&ly black; and yet fuch animals fee even more di- ftimftly than others. If the feat of vifion be at the farther furface of the retina, and if vifion be performed by direft rays, a white choroid coat could be of no ufe ; and if it were by reflefted rays, a black one could not anfwer the pur- pofe. It is likewife an argument in favour of the choroides being the organ of vifion, that it is a fubftance which receives a more diftinft impreflion from the rays of light than any other membrane in any part of the animal fy- ftem, excepting, perhaps, that white cuticle which lies under the feales of fifties : whereas the retina is a fub¬ ftance on which the light makes an exceedingly faint impreftion, and perhaps no impreffion at all; fince light in pafling out of one tranfparent medium into another immediately contiguous to it, fuffers no refraction or re¬ flexion, nor are any of the rays abforbed unlcfs there is fome difference in the refraCting power of the two media, which probably is not the cafe between the reti¬ na and the vitreous humour which is in contad with it: And wherever the light is not afteCfed by the medium on which it falls, we can hardly fuppofe the medium to receive any impreffion from the light, the aCtion being probably always mutual and reciprocal. Befides, the retina is fo fituated, as to be expofed to many rays befides thofe which terminate in it, and which, therefore, cannot be fubfervient to vifion, if it be per¬ formed there. Now this is not the cafe with the cho¬ roides, which is in no fhape tranfparent, and has no re¬ flecting fubftanee beyond it. It is, befides, peculiarly favourable to the opinion of Marriotte, that we can then fee a fufficient reafon for the diverfity of its colour in different animals, according as they are circumftanced with refpeCt to vifion. In all tcrreftrial animals, which ufe their eyes by night, the 4 ICS. 221 choroides is either of a bright white, or of fome very vivid Of Vifion- colour, which refleCts the light very ftrongly. On this account vifion may be performed with lefs light, but it cannot be with great diftinClnefs, the reflection of the rays doubling their effeCf, fince it muft extend over fome fpace, all reflection being made at a diftance from the reflecting body. Befides, the choroides in brutes is not in general perfectly white, but inclined to blue ; and is therefore, probably, better adapted to fee by the fainter coloured light, which chiefly prevails in the night; and we would add, is on the fame account more liable to be ftrongly impreffed by the colours to which they are chiefly expofed. On the other hand, the choroides of birds in general, efpecially eagles, hawks, and other birds of prey, is black ; by which means they are able to fee with the greateft diftinClnefs, but only in bright day light. The owl, however, feeking her food by night, has the cho¬ roides white like that of a cat. In the eyes of man, which are adapted to various ufes, the choroides is nei¬ ther fo black as that of birds, nor fo white as that of thofe animals who make the greateft ufe of their eyes in the night. As to a third hypothefis, which is in effeCt that of M. de la Hire, and which makes both the retina and the choroides equally neceffary to vifion, and fuppofes it to be performed by the impreffion of light on the cho¬ roides communicated to the retina ; Mr Michell ob- ferves, that the perceptions can hardly be fuppofed to be fo acute, when the nerves do not receive the impreffions immediately, but only after they have been communi¬ cated to another fubftance. Befides, it muft be more natural to fuppofe, that, when the principal impreffion is made upon the choroides, it is communicated to the brain by its own nerves, which are fufficient for the pur- pofe. . # 138 The dimenfions and precife form of the fpot in the Dimenfions eye in which there is no vifion, were more accurately the fPot calculated by Daniel Bernouilli, in the following man-eye ner. He placed a piece of money, O, upon the1 floor ; dbere^ no and then (hutting one of his eyes, and making a pendu-vifion. lum to fwfing, fo that the extremity of it might be near- Hate ly in the line AO, he obferved at what place C it be- CC^LXXXI°- gan to be invifible, and where it again emerged into S’ view at A. Raifing the pendulum higher and lower, he found other points, as H, N, P, G, B, .at which it began to be invifible.; and others, as M, L, E, A, at which it began to be vifible again; and drawing a curve through them, he found that it was elliptical; and, with refpecl to his own eye, the dimenfions of it were as fol¬ low ; OC was 23, AC 10, BD 3, DH 13, and EG 14 ; fo that the centre being at F, the greater axis w'as to the lefs as 8 to 7. From thefe data the plane on which the- figure was drawn being obliquely fituated with refpecl to the eye, he found, that the place in the eye that correfponded to it was a circle, the diamefter of which was a feventh part of the diameter of the eye, the centre of it beino- 27 parts of the diameter from the point oppofite to the pupil, a little above the middle. In order, therefore, that this fpace in which there is no vifion may be as fmall as poffible, it is necefljary that the nerve ffiould en¬ ter the eye perpendicularly, and that both this end, and alfo its entering the eye at a diftance from its axis, are gained by the particular manner in which the two optic nerves O P T Of Vifion. nerves unite and become feparate again, by croffing ' v ‘ 0ne another. In fupport of one of the obfervations of Mr Michel], Dr Prieftley obferves, that Aquapendente mentions the cafe of a perfon at Pifa, who could fee very well in the night, but very little or none at all in the day time. This is alfo faid to be the cafe with thofe white people among the blacks of Africa, and the inhabitants of the ifthmus of America, Avho, from this circumitance, are called moon-eyed. Dr Prieftley thinks it probable that their choroides is not of a dark colour, as it is in others of the human fpecies ; but white or light-coloured, as in thofe animals which have moft occafion for their eyes 139 in the night. Arguments Dr Porterfield obferves, that the reafon why there is for the re- , no vifion at the entrance of the optic nerve into the eye, thefeat;61 fSmay be its want of that foftnefs and delicacy which it vifion. has when it is expanded upon the choroides ; and that, in thofe animals in which that nerve is inferted in the axis of the eye, it is obferved to be equally delicate, and therefore probably equally fenfible, in that place as in any other part of the retina. In general, the nerves, when embraced by their coats, have but little fenfibility in comparifon of what they are endued with when they are divefted of them, and unfolded in a foft and pulpy fubftancc. Haller obferves, that the choroides cannot be univer- fally the feat of vifion, becaufe, fometimes in men and birds, but efpecially in fifties, it is covered internally with a black mucus, through which the rays cannot pene¬ trate. This ivriter fpeaks of a fibrous membrane in the retina diftinft from its pulpy fubftance. On thefe fi¬ bres, he conje&ures, that the images of objects are la Hire’s argument in favour of the retina, from the analogy of the fenfes, is much ftrengthened by confidering that the retina is a large nervous appa¬ ratus, immediately expofed to the impreflion of light ; Avhereas the choroides receives but a flender fupply of ner\res, in common A\Tith the fclerotica, the conjunc¬ tiva, and the eyelids, and that its nerves are much lefs expofed to the light than the naked fibres of the optic nerve. That the optic nerve is of principal ufe in vifion, is farther probable from feveral phenomena attending fome of the difeafes of the eye. When an amaurofis has af- fedted one eye only, the optic nerve of that eye has been found manifeftly altered from its found ftate. Dr Prieft¬ ley Avas prefent xvhen Mr Hey examined the brain of a young girl, Avho had been blind of one eye, and faw that the optic nerve belonging to it Avas confiderably fmaller than the other ; and he informed him, that up¬ on cutting into it it Avas much harder, and cineritious. Morgagni mentions tsvo cafes, in one of Avhich he found the optic nerves fmaller than ufual, and of a cineritious colour, when, upon inquiry, he Avas informed that the perfon had not been blind, though there might have been fome defedt in the fight of one of the eyes. In the other cafe, only one of the optic nerves Avas affedted in that manner, and the eye itfelf Avas in other refpedts very perfedt. Here, alfo, he Avas exprefsly told, that the perfon Avas not blind of that eye. Befides, as the optic nerve is folely fpent in forming the retina, fo no fundlion of the eye not immediately ifubfervient to vifion, is aftedted by an amaurofis. On painted M. I 5 I C S. Part I. the contrary, thofe nerves which go to the choroides OfVifion. are found to retain, in this difeafe, their natural in- v~--J fluence. The iris Avill contract in a recent gutta ferena of one eye, if the other remains found, and is fuddenly expofed to a ftrong light. The fclerotica, conjundtiva, and eyelids, which receive their nerves from the fame branches as the choroides, retain their fenfibility in this diforder. » The manner in svhich perfons recover from an amau¬ rofis, favours the fuppofition of the feat of vifion being- in the retina : fince thofe parts Avhich are the moft di . ftant from the infertion of the nerve recover their fenft- biiity the fooneft, being in thofe places the moft pulpy and foft •, A\rhereas there is no reafon to think that there is any difference in this refpedt in the different parts of the choroides. Mr Hey has been repeatedly informed, by perfon? labouring under an imperfedt amau¬ rofis, or gutta ferena, that they could not, when look¬ ing at any objedt Avith one eye, fee it fo diftindlly Avhen it Av-as placed in the axis of the eye, as Avhen it Avas fi- tuated out of the axis. And thofe perfons Avhom he had knoAvn to recover from a perfedt amaurofis, firft difeo- vered the objedts whofe images fell upon that part of the retina which is at the greateft diftance from the op¬ tic nerv'e. We fhall conclude thefe remarks Avith obferving, that if the retina be as tranfparent as it is generally reprefent- ed to be, fo that the termination of the pencils muft ne- ceffarily be either upon the choroides, or fome other opaque fubftance interpofed between it and the retina, the adtion and readtion occafioned by the rays of light being at the common furface of this body and the retina, both thefe mediums (fuppofing them to be equally fenfi¬ ble to light) may be equally affedted ; but the retina, being naturally much more fenfible to this kind of im- preffion, may be the only inftrument by Avhich the fen- fation is conA^eyed to the brain, though the choroides, or the black fubftance Avith Avhich it is fometimes lined, may alfo be abfolutely neceffary to vifion. This is not far from the hypothefis of M. de la Hire, and Avill com¬ pletely account for the entire defedt of vifion at the in¬ fertion of the optic nerve. I^0 Vifion is diftinguiftied into bright and obfeure, dijlincl Of bright and indijlinft.—It is faid to be bright, when a fufficient andobfeure, number of rays enter the pupil at the fame time 5 ob- ai,'e** was the opinion of Sir Ifaac Newton and others, that objects appear fingle, becaufe the tvro optic nerves unite before they reach the brain. But Dr Porterfield fliow's, from the obfervation of feveral anatomifts, that the op¬ tic nerves do not mix, or confound their fubftance, be¬ ing only united by a clofe cohefion j and objefls have appeared fingle where the optic nerves were found to be disjoined. Dr Briggs fuppofed that fingle vifion was owing to Solutions the equal tenfion of the correfponding parts of the op- of this dif. tic nerves, whereby they vibrated in a fynchronous man-ficulty.l)y ner. But, befides feveral improbable circumftances in ^>r this account, Dr Porterfield {hows that fads do by no means favour it. To account for this phenomenon, this ingenious writ¬ er fuppofes, that by an original law in our natures, wre imagine objeds to be fituated fomewhere in a right line drawn from the pidure of it upon the retina, through the centre of the pupil. Confequently, the fame objed ^7 appearing to both eyes to be in the fame place, the Dr Porter- mind cannot diftinguilh it into turn. In anfwer to an objedion to this hypothefis, from objeds appearing double when one eye is diftorted, he fays the mind mif- takes the pofition of the eye, imagining that it had moved in a manner correfponding to the other, in which cafe the conclufion W'ould have been juft. This principle, however, has been thought fufficient to account for this appearance. Originally, every ob¬ jed, making two pidures, is imagined to be double j but by degrees, we find, that when two correfponding parts of the retina are impreffed, the objed is but one 5 but if thofe correfponding parts be changed, by the dif- tortion of one of the eyes, the objed muft again appear double as at the firft. This has been thought verified by Mr Chefelden j who informs us, that a gentleman, who from a blow on his head had one eye diftorted, found every objed to appear double j but by degrees the Theory. OPT 14S Dr Held, r.»d 149 Dr Wells. Of Vifion. the moft familiar ones came to appear fingle again, and — ' in time all objects did fo, without any amendment of the diftortion. On the other hand, Dr Reid is of opinion, that the correfpondence of the centres of the two eyes, on which fingle vifion depends, does not arife from euftom, but from feme natural conftitution of the eye and of the mind. He makes feveral juft objections to the cafe of Mr Forfter, recited by Dr Smith and others; and thinks that the cafe of the young man couched by Chefelden, who faw fingly with both eyes immediately upon receiv¬ ing his fight, is nearly decifire in proof of his fuppofi- tion. He alfo found that three young gentlemen, whom he endeavoured to cure of fquinting, faw objects fingly, as foon as ever they were brought to direft the centres of both their eyes to the fame objedf, though they had never been ufed to do fo from their infancy; and he ob- ferves, that there are cafes, in which, notwithftanding the fulleft convidlion of an objedi being fingle, no prac¬ tice of looking at it will ever make it appear fo, as when it is feen through a multiplying glafs. To all thefe folutions of the difficulty refpedling fingle vifion by both eyes, objedlions have been lately made which feem infurmountable. By judicious experi¬ ments, Dr Wells has fliown, that it is neither by cuftom alone, nor by the original property of the eyes alone, that objedls appear fingle ; and having demolifhed the theories of others, he thus endeavours to account for the phenomenon. “ The vifible place of an objedt being compofed of its vifible diftance and vifible diredlion, to Aioav how it may appear the fame to both eyes, it will be neceflapy * Etfay on (fays he *) to explain in what manner the diftance and diredlion, which are perceived by one eye, may co- 1 ’ ’ incide with thofe which are perceived by the other.” With refpedf to vifible diftance, the author’s opinion feems not to differ from that which we haveftated elfe- where (fee Metaphysics, N° 49, 50.); and therefore we have to attend only to what he fays of vifible direc¬ tion. When a fmall objedt is fo placed with refpedf to either eye, as to be feen more diftindtly than in any other fituation, our author fays that it is then in the optic axis, or the axis of that eye. When the two optic axes are diredted to a fmall objedl not very di- ftant, they may be conceived to form two fides of a triangle, of which the bafe is the interval between the points of the corners where the axes enter the eyes. This bafe he called the vifual bafe; and a line drawn from the middle of it to the point of interfedlion of the optic axis he calls the common axis. He then pro¬ ceeds to (how, that objedts really Jituated in the optic axis do not appear to be in that line, but in the common axis. Every perfon (he obferves) knows, that if an objedl be viewed through two fmall holes, one applied to each eye, the two holes appear but as one. The theories hitherto invented afford two explanations of this fadf. According to Aguilonius, Dechales, Dr Porterfield, and Dr Smith, the two holes, or rather their borders, will be feen in the fame place as the objedl viewed through them, and will confequently appear united, for the fame reafon that the objedl itfelf is feen fingle. But whoever makes the experiment will diftindlly perceive, that the united hole is much nearer to him than the objedl; not Vol. XV. Part I. I c s. 22 r* to mention, that any fallacy on this head might be cor- redled by the information from the fenfe of touch, that the card or other fubiiance in which the holes have been made is within an inch or lefs of our face. The other explanation is that furnithed by the theory of Dr Reid. According to it, the centres of the retinas, which in this experiment receive the pidlures of the holes, will, by an original property, reprefent but one. This theory, however, though it makes the two holes to appear one, does not determine where this one is to be feen. It can¬ not be feen in only one of the perpendiculars to the images upon the fetinas, for no realon can be given why this law, of vifible diredtion, which Dr Reid thinks eftablithed beyond difpute, if it operates at all, ffiould not operate upon both eyes at the fame time ; and if it be feen by both eyes in fuch lines, it muft appear where thofe lines crofs each other, that is, in the fame place with the objedl viewed through the holes, which, as I have already mentioned, is contrary to experience. Nor is it feen in any diredlion, the confequence of a law af- fedling both eyes confidered as one organ, but fufpend- ed when each eye is ufed feparately. For when the two holes appear one, if we pay attention to its fitua¬ tion, atid then clofe one eye, the truly fingle hole will be feen by the eye remaining open in exadlly the fame diredlion as the apparently fingle hole was by both eyes. wi v moils “ Hitherto I have fuppofed the holes almoft touching the face. But they have the fame unity of appearance, in whatever parts of the optic axes they are placed ; whether both be at the fame diftance from the eyes, or one be clofe to the eye in the axis of which it is, and the other almoft contiguous to the objedl feen through them. If a line, therefore, be drawn from the objedl to one of the eyes, it will reprefent all the real or tan¬ gible pofitions of the hole, which allow the objedl to be feen by that eye, and the whole of it will coincide with the optic axis. Let a fimilar line be drawn to the other eye, and the two muft appear but as one line ; for if they do not, the two holes in the optic axes will not, at every diftance, appear one, whereas experiments prove that they do. This united line will therefore reprefent the vifible diredlion of every objedl fituated in either of the optic axes. But the end of it, which is toivards the face, is feen by the right eye to the left, and by the left eye as much to the right. It muft be feen then in the middle between the two, and confequently in the com¬ mon axis. And as its other extremity coincides with the point where the optic axes interfedl each other, the whole of it muft lie in the common axis. Hence the truth of the propofition is evident, that objedts fituated in the optic axis, do not appear to be in that line, but in the common axis.” He then proves by experiments, that objedts fituated in the common axis did not appear to be in that line, but in the axis of the eye by which they are not feen: that is, an objedl fituated in the common axis appears to the right eye in the axis of the left, and vice verfa. His next propofition, proved likewife by experiments, is, that “ objedls, fituated in any line drawn through the mutual interfedlion of the optic axes to the vifual bafe, do not appear to be in that line, but in another drawn, through the fame interfedlion, to a point in the vifual bafe diftant half this bafe from the fimilar extremity of the former line towards the left, if the objedls be F f feen 226 OPT Of Vifion. 150 Objeifls feen with both eyes appear brighter than when feen with one. feen by the right eye, but towards the right if feen by the Jeft eye.” From thefe propofitions he thus accounts for Angle vifion by both eyes. “If the queftion be concerning an objedl at the concourfe of the optic axes, it is feen Angle, becaufe its two fimilar appearances, in regard to fize, lhape, and colour, are feen by both eyes in one and the fame direction, or if you will, in two diredlions, which coincide with each other through the whole of their extent. It therefore matters not whether the di¬ fiance be truly or falfely eftimated ; whether the object be thought to touch our eyes, or to be infinitely remote. And hence we have a reafon, which no other theory or vifible direction affords, why objedls appeared fingle to the young gentleman mentioned by Mr Chefelden, im¬ mediately after his being couched, and before he could have learned to judge of diftance by fight. “ When two fimilar objefts are placed in the optic axes, one in each, at equal diftances from the eyes, they will appear in the fame place, and therefore one, for the fame reafon that a truly fingle objedl, in the concourfe of the optic axes, is feen fingle. “ To finifh this part of my fubjeft, it feems only neceflary to determine, whether the dependence of vifi¬ ble dire&ion upon the adlions of the mufcles of the eyes be eftablilhed by nature, or by cuftom. But fafts are here wanting. As far as they go, however, they ferve to prove that it arifes from an original principle of our conftitution. For Mr Chefelden’s patient faw ob- je£Is fingle, and confequently in the fame direftions with both eyes, immediately after he was couched ; and per- fons aftedted with fquinting from their earliell infancy fee objedls in the fame diredlions with the eye they have never been accuftomed to employ, as they do with the other they have conftantly ufed.” We are indebted to Dr .Turin for the following cu¬ rious experiments, to determine whether an objedl feen by both eyes appears brighter than when feen with one only. He laid a flip of clean white paper diredtly before him on a table, and applying the fide of a book clofe to his right temple, fo that the book was advanced con- fiderably farther forward than his face, he held it in fuch a manner, as to hide from his right, eye that half of the paper which lay to his left hand, while the left half of the paper was feen by both eyes, without any impediment. Then looking at the paper with both eyes, he ob- ferved it to be divided, from the top to the bottom, by a dark line, and the part which was feen with one eye only w:as manifeftly darker than that which w7as feen with both eyes ; and, applying the book to his left temple, he found, by the refult of the experiment, that both his eyes were of equal goodnefs. He then endeavoured to determine the excefs of this brightnefs *, and comparing it with the appearance of an objedt illuminated partly by one candle and partly by two, he was furprifed to find that an objedt feen with two eyes is by no means twice as luminous as when it is feen with one *, and after a number of trials, he found, that when one paper was illuminated by a candle placed at the diftance of three feet, and another paper by the fame candle at the fame diftance, and by another candle at the diftance of 11 feet, the former feen by both eyes apd the latter with one eye only, appeared to be of I C S. Part I. equal whitenefs 5 fo that an objedl feen with both eyes Of Vifion. appears brighter than when it is feen with one only by v"—“v— about a 13th part. Fie then proceeded to inquire, whether an objedt feen with both eyes appears larger than when feen with one ; but he concluded that it did not, except on account of fome particular circumftances, as in the cafe of the bi¬ nocular telefcope and the concave fpeculum. M. du Tour maintains, that the mind attends to no more than the image made in one eye at a time } and produces feveral curious experiments in favour of this hypothefis, which had alfo been maintained by Kepler and almoft all the nrft opticians. But, as M. Buffon obferves, it is a fufficient anfwer to this hypothefis, how¬ ever ingenioufly it may be fupported, that we fee more diftindtly w'ith two eyes than with one ; and that when a round objedt is near us, we fee more of the furface in. one cafe than in the other. With refpedl to fingle vifion with tw'o eyes, Dr Hartley obferves, that it deferves particular attention, that the optic nerves of men, and iiich other animals as look the fame way with both eyes, unite in the ctlla turcica in a ganglion, or little brain, as one may call it, peculiar to themfelves ; and that the affociations betw een fynchronous impreflions on the two retinas muft be made fooner and cemented ftronger on this account: alfo that they ought to have a much greater pow'er over one ano¬ ther’s images, than in any other part of the body. And thus an impreflion made on the right eye alone, by a fingle objedl, may propagate itfelf into the left, and there raife up an image almoft equal in vividnefs to it¬ felf ; and confequently when we fee with one eye only, we may, however, have pictures in both eyes. A curious deception in vifion, arifing from the ufe of both eyes, was obferved and accounted for by Dr Smith. It is a common obfervation, he fays, that ob- jedts feen w ith both eyes appear more vivid and ftrong¬ er than they do to a fingle eye 5 efpecially when both of them are equally good. A perfon not fhort-fighted may foon be convinced of this fadt, by looking at¬ tentively at objedts that are pretty remote, firft with one eye, and then with both. This obfervation gave occafion to the conftrudlion of the binocular telefcope, in the ufe of which the phenomenon is ftill more ftrik- in ot,01’"obftru6t the ray EH 5 but when it is filled with water ■Media of to the height GH, the ray at EK being refracted at the different furface of the "water into the line KF, the eye at F lhall Forms, fee the object by means of that. ' ^ In like manner, an object fituated in the horizon AnobjeH app^^s above its true place, on account of the re- fituated in fraction of the rays which proceed from it in their the horizon paflage through the atmofphere. For, firft, If the ob- appears je(cj, fjtuated beyond the limits of the atmofphere, true place ^rays entering it will be refrafted towards the per¬ pendicular ; that is, towards a line drawn from the point where they enter, to the centre of the earth, which is the centre of the atmofphere : and as they pafs on, they will be continually refradted the fame way’, beeanfe they are all along entering a denfer part, the centre of whofe convexity is ftill the fame point; upon which account the line they defcribe will be a curve bending down¬ wards : and therefore none of the rays that come from that object can enter an eye upon the furface of the earth, except "what enter the atmofphere higher than they need to do if they could come in a right line from the objedt : confequently the objedt mult appear above its proper place. Secondly, If the objedt be placed within the atmofphere, the cafe is Itill the fame; for the rays which flow from it mult continually enter a denfer medium whofe centre is below the eye ; and therefore being refradted towards, the centre, that is, downwards as before, thofe which enter the eye fnuft neceflarily proceed as from fome point above the ob¬ jedt ; whence the objedt will appear above its proper place. Hence it is, that the fun, moon, and ftars, appear above the horizon, when they are juft below it; and higher than they ought to do, when they are above it: Likewife diftant hills, trees, &c. feem to be higher than , they are. Befides, The lower thefe objedts are in the horizon, the greater is the obliquity with which the rays which flow from them enter the atmofphere, or pafs from the rarer into the denfer parts of it; and therefore they ap¬ pear to be the more elevated by refradHon : on which account the lower parts of them are apparently more elevated than the reft. This makes their upper and under parts feem nearer than they are ; as is evident from the fun and moon, w’hich appear of an oval form when they are in the horizon, their horizontal diame¬ ters appearing of the fame length that they would do if the rays fuffered no refradh’on, while their vertical ones are thus fhortened. Prop. II. An object feen through a medium terminated by plane and parallel furfaces, appears nearer^ 1S4 brighter, and larger, than with the naked eye. feen°tW ■F?r inftance»let (fig- 7-) be the objedt, CDEFthe a plane me- medium, and GH the pupil of an eye, which is here dium ap- drawn large to prevent confufion in the figure.—And, pears nearer x. Let RK, RL, be two rays proceeding from the pointR, trthan'Yeen anC* enter*ng ^ denfer medium at K and L; thefe rays by the nak-fiere ^ refradtion be made to diverge lefs, and to ed eye. proceed afterwards, fuppofe in the lines K a, L b ; at « Plate and b, where they pafs out of the denfer medium, they eccLxxxt. be as much refracted the contrary way, proceeding I c s. Part I. in the lines a c, b d, parallel to their finft diredtions. Appear. Produce thefe lines back till they meet in e: this will a.nc® °£ Ob- be the apparent place of the point R ; and it is evident 'Media of from the figure, that it muft be nearer the eye than that different point; and becaufe the fame is true of all other pencils Forms, flowing from the objedt AB, the whole will be feen in' y— the fituation fg, nearer to the eye than the line AB. 2. As the rays RK, RL would not have entered the eye, but have paffed by it in the diredtions Kr, L /, had they not been refradted in pafling through the me¬ dium, the objedt appears brighter. 3. The rays A B £, will be refradted at /i and i into the lefs conver¬ ging lines /i k, i /, and at the other furface into k M, f M,. parallel to A h and B i produced ; fo that the ex¬ tremities of the objedt will appear in the lines M £, M / produced, viz. in f and g, and under as large an angle /Mg, as the angle B under which an eye at q would have feen it had there been no medium inter- pofed to refradt the rays 1 and therefore it appears larger to the eye at GH, being feen through the in- terpofed medium, than otherwife it, would have done. But it is here to be obferved, that the nearer the point e appears to the eye on account of the refradHon of the rays RK, RL, the fticrter is the image fg, becaufe it is terminated by the lines Mf and M^, upon which account the objedt is made to appear lefs; and there¬ fore the apparent magnitude of an objedt is not much augmented by being feen through a medium of this form. Farther, it is apparent from the figure, that the ef- fedt of a medium of this form depends wholly upon its thicknefs; for the diftance betw-een the lines R r and e c, and confequently the diftance between the points e and R, depends upon the length of the line K a :•—. Again, The diftance betw'een the lines AM and depends on the length of the line h k ; but both K n and k h depend on the diftance between the furfaces CE and DF, and therefore the effedt of this medium depends upon its thicknefs. Prop. III. An objedft feen through a convex lens, appears larger, brighter, and more diftant, than with the naked eye. To illuftrate this, let AB (fig. 8.) be the objedl, CD Seeruhro* the lens, and EF the eye. I. From A and B, the extre- a convex mities of the objedt, draw the lines AY r, BX r, crofting lens> each other in the pupil of the eye; the angle A?-B com- brig^ter^ prehended between thefe lines, is the angle under which and more the objedt would be feen with the naked eye. But by diftant. the interpofition of a lens of this form, whofe property Gg- 8. it is to render converging rays more fo, the rays AY and BX will be made to crofs each other before they, reach the pupil. There the eye at E will not perceive the extremities of the objedt by means of thefe rays (for they will pafs it without entering), but by fome others which muft fall without the points Y and X, or be¬ tween them ; but if they fall between them, they will be made to concur fooner than they themfelves would have done : and therefore, if the extremities of the ob- jedt could not be feen by them, it will much lefs be feen by thefe. It remains therefore* that the rays which will enter the eye from the points A and B after refrac¬ tion, muft fall upon the lens vfithout the points Y and Theoi'y- OPT Appear- X j let then the rays AO and BP be fuch. Thefeaf- incf of Ob- ter refraction entering the eye at r, the extremities of ^jYIedia of t^e be feen in the lines r r T, produced, different and under the optic angle Q^rT, which is larger than Form'i. A r B, and therefore the apparent magnitude of the ob- y "" ' ject will be increafed.—2. Let GHI be a pencil of rays flowing from the point G ; as it is the property of this lens to render diverging rays lefs diverging, parallel, or converging, it is evident that fome of thofe rays, which would proceed on to F and E, and mifs the eye were they to fuffer no refraction in palling through the lens, will now enter it j by which means the objeft will ap¬ pear brighter. 3. The apparent diftance of the objeCt will vary according to the fituation of it with refpeCt to the focus of parallel rays of the lens. 1. Then, let us fuppofe the objeft placed fo much nearer the lens than its focus of parallel rays, that the refraCted rays KE and LF, though rendered lefs diverging by palling through it, may yet have a confiderable degree of divergency, fo that we may be able to form a judgment of the dif¬ tance of the objeCt thereby. In this cafe, the object ought to appear where EK, FL produced back concur; which, becaufe they diverge lefs than the rays GH, GI, will be beyond G, that is, at a greater diftance from the lens than the objeCt is. But becaufe both the brightnefs and magnitude of the objeCt will at the fame time be augmented, prejudice will not permit us to reckon it quite fo far off as the point where thofe lines meet, but fomewhere between that point and its proper place. 2. Let the objeCl be placed in the focus of pa¬ rallel rays, then will the rays KE and LF become pa¬ rallel ; and though in this cafe the object would appear at an immenfe diftance, if that diftance were to be judged of by the direction of the rays KE and LF, yet on account of its brightnefs and magnitude we lhall not think it much farther from us than if it were feen by plate the naked eye. 3. If the objeCt be fituated beyond the cclxxxi. focus of parallel rays, as in BA, the rays flowing from fig- 9. it, and falling upon the lens CD, will be collected into their refpeCtive foci at a and b, and the intermediate points /«, «, &c. and will there form an image of the objeCt AB ; and after crofting each other in the feveral points of it, as expreffed in the figure, will pafs on di¬ verging as from a real objeCt. Now if an eye be fitua- ed at r, where Ac, B r, rays proceeding from the ex¬ treme points of the objeCt, make not a much larger angle A c B, than they would do if no lens were inter- pofed, and the rays belonging to the fame pencil do not converge fo much as thofe which the eye would receive if it were placed nearer to a or Z», the objeCt upon thele accounts appearing very little larger or brighter than with the naked eye, is feen nearly in its proper place : but if the eye recede a little way towards a b, the objeCt then appearing both brighter and larger feems to approach the lens: which is an evident proof of what has been fo often afferted, viz. that we judge of the diftance of an objeCt in fome meafure by its bright¬ nefs and magnitude ; for the rays converge the more the farther the eye recedes from the lens •, and there¬ fore if we judged of the diftanee of the objeCt by the direction of the rays which flow from it, we ought in this cafe to conceive it at a greater diftance, than when the rays were parallel, or diverged at their entrance into the eye That the objeCt ftiould feem to approach the lens in. 1 ^ O. 229 this cafe, was a difficulty that puzzled Dr Barrow, and Appear- which he pronounces infuperable, and not to be ac- a?ce ot Ob- counted for by any theory we have of vifion. Mo- 'Ivi^dia of lineux alfo leaves it to the folution of others, as that different which will be inexplicable, till a more intimate know- Forms, ledge of the vifive faculty, as he expreffes it, be obtain- v— ed by mortals. t hey imagined, that fince an objeCt appears farther off, the lefs the rays diverge which fall upon the eye, if they fhould proceed parallel to each other, it ought to appear exceeding remote ; and if they fhould con¬ verge, ft fhould then appear more diftant ftill: the rea- fon of this was, becaufe they looked upon the apparent place of an objeCt, as owing only to the direction of the rays whatever it was, and not at all to its apparent magnitude or fplendour. Perhaps it may proceed from our judging of the dif¬ tance of an objeCt in fome meafure by its magnitude, that the deception of fight commonly obferved by tra¬ vellers may arife ; viz. that upon the firft appearance of a budding larger than ufual, as a cathedral church, or the like, it generally feems nearer to them, than they afterwards find it to be. Prop. IV. If an obje£t be placed farther from a convex lens than its focus of parallel rays, and the eye be fituated farther from it on the other fide than the pace where the rays of the feveral pencils are collected into their proper foci, the objeCt appears inverted, and pendulous in the air, be¬ tween the eye and the lens. To explain this, let AB reprefent the objeCt, CD the In cerfain 1 lens ; and let the rays on the pencil ACD be collected circum- in a, and thofe of BCD in b, forming there.an inverted ftances a« 1 image of the objeCt AB, and let the eye be placed in hT* F : it is apparent from the figure, that fome of the re- convex lens fraCted ray s which pafs through each point of the image appears in¬ fill enter the eye as from a real objeCt in that place • verted and and therefore the objeCt AB will appear there, as the Pendulous propofition yfferts. But we are fo little accuftomed to m 116 ^ fee objeCts in this manner, that it is very difficult to FlS‘9* perceive the image with one eye; but if both eyes are fituated in fuch a manner, that rays flowing from each point of the image may enter both, as at G and H, and we direCt our optic axes to the image, it is eafy to be perceived. If the eye be lituated in a or b, or very near them on either fide, the objeCt appears exceedingly indiitinCt, viz. if at r/, the rays which proceed from the fame point of the objeCt converge fo very much, and if at e they diverge fo much, that they cannot be collected together upon the retina, but fall upon it as if they were the axes of fo many diftinCt pencils coming through every point of the lens; wherefore little more than one Angle point of the objeCt is feen at a time, and that appears all over the lens ; whence nothing but indiftinCL nefs arifes. If the lens be fo large that both eyes may be ap¬ plied to it,, as in h and £, the objeCt will appear double; for it is evident from the figure, that the rays which enter the eye at h from either extremity of the objeCt A or B, do not proceed as from the fame point with that 230 Appear¬ ance ot Ob different Forms. I5? An objedl through a OPT tliat from tvlience thofe which enter the other at k feem uilc ui ^u-to ^ow . t]ie mind therefore is here deceived, and looks Ivbjdia^of uPon the object as fituated in two different places, and therefore judges it to be double. Prop. V. An object feen through a concave lens appears nearer, fmaller, and lefs bright, than with the concave , , lens is feen naked eye. fmaller and Thus, let AB (fig. 10.) be the objedt, CD the pupil lefs bright of an eye, and EF the lens. Now, as it is the propelty of a lens of this form to render diverging rays more fo, and converging ones lefs fo, the diverging rays Gxi, GI, proceeding from the point G, will be made to diverge more, and fo to enter the eye as from fome nearer point g; and the rays AH, BI, which converge, will be made to converge lefs, and to enter the eye as from the points a and b ; wherefore the objefts wUl appear in the fituation ctgh, lefs and nearer than without the lens. Further, As the rays which proceed from G are render¬ ed more diverging, fome of them will pais by the pu¬ pil of the eye, which otherwife would have entered it, and therefore each point of the objedt will appear lefs bright. Prop. VI. than with the naked eye. Fig. 10. An objedb feen through a polygonal glafs, that is, one which is terminated by feveral plain furfa- ces, is multiplied thereby. Plate Let A be an objedl, and BC a polygonous glafs ter- ccclxxxi. niJnated by the plane furfaces ED, DE, &c. and let f's- 11, j.]ie fituation of the eye F be fuch, that the rays AB be¬ ing refradted in paffing through the glafs, may enter it in the direction BF, and the rays AC in the diredion CF. Then will the eye, by means of the former, fee the objedt in G, and by the latter in H ; and by means of the rays AI, the objedt will alfo appear in its proper fituation A. Sect. VII. On the RefleBion of Light. 158 Some por- When a ray of light falls upon any body, however tion of light transparent, the whole of it never paffes through the fi eft ed from body, but fome part is always refledted from it-, and tranfparent it is by this refleded light that all bodies which have bodies. no light of their own become vifible to us. Of that part of the ray which enters, another part is alfo reflec¬ ted from the fecond furface, or tbat_ which is fartheft from the luminous body. When this part arrives again at the firft furface, part of it is refleded back from that furface ; and thus it continues to be refleded between the two furfaces, and to pafs backwards and forwards within the fubftance of the medium, till fome part is totally extinguiflied and loft. Belides this inconfider- able quantity, however, which is loft in this manner, (he fecond furface often refleds much more than the firft ; fo that, in certain pofitions, fcarcely any rays will f.afs through both fides of the medium. A very conft- derable quantity is alfo unaccountably loft at each re- fleding furface ; fo that no body, however tranfparent, can tranfmit all the rays which fall upon it neither, though it be ever fo well fitted for refledion, will it re¬ tied them all. I c s. Part I, n , Caufe of On the Caufe of RefeBion. Refleftion. The refledion of light is not fo eafily accounted for as y ~ ' J refradion. This lalt property may be accounted for in a fatisfadory manner, by the fuppofition of an attrac-. tive power diffufed throughout the medium, and extend¬ ing a very little way beyond it 5 but with regard to the refledion of light, there feems to be no fatisfadory hypothelis hitherto invented. Of the principal opinions on this fubjed Mr Rowning has given us the following account. i_9 I. It was the opinion of philofophers, before Sir Ifaac Light is Newton difeovered the contrary, that light is refleded n°t reflect, by impinging dpon the folid parts of bodies. But that1'1 b>’im- this is not the cafe is evident from the following reafons.Ihe^iohd'1 Firft, It is net refleded at the firft furface of a body parts of by impinging againft it. For in order that the light bodies at may be regularly refleded, there fliould be no afperi-fur. ties or unevennefs in the refleding furface large enough “ ’ to bear a fenflble proportion to the magnitude of a ray of light ; becaufe if the furface abound with thefe, the incident rays would be irregularly fcattered rather than refleded with that regularity with which light is ob- ferved to be from a well polilhed furface. Now thofe furfaces, which to our fenfes appear perfedly fmooth and well polilhed, are far from being fo ; for to pulifh, is only to grind off the larger protuberances of the me¬ tal with the rough and fharp particles of emery, which muft of neceflity leave behind them an infinity of alteri¬ ties and feratches, which, though inconfiderable with re¬ gard to the former roughneffes, and too minute to be difeerned by us, muft neverthelefs bear a large propor¬ tion to, if not vaftly exceed, the magnitude of the par¬ ticles of light. j£0 . Secondly, It is not refleded at the fecohd furface by nor at the impinging againft any folid particles. That it is not fecond. refleded by impinging upon the fulid particles which conftitute this' fecond furface, is fufticiently obvious from the foregoing argument; the fecond furfaces of bodies being as incapable of a perfed polifh as the firft : and it is farther confirmed from this, viz. that the quantity of light refleded differs according to the different denfity of the medium behind the body. It is likewife not re¬ fleded by impinging upon the particles which conftitute the furface of the medium behind it, becaufe the ftrong- eft refledion at the fecond furface of a body, is when there is a vacuum behind it. ^ II. It has been the opinion of fome, that light is re-sUpp0fuion fleded at the firft furface of a body, by a repulfive force of a repul- equally diffufed over it : and at the fecond, by an at-five f°rce! tradive force. i6z X. If there be a repulfive force diffufed over the fur-objeftedto. face of bodies that repels the rays of light, then, fince by increafing the obliquity of a ray we diminifh its per¬ pendicular force (which is that only whereby it muft make its way through this repulfive force), however weakly that force may be fuppofed to ad, rays of light may be made to fall with fo great a degree of obliquity on the refleding furface, that there fhall be a total re¬ fledion of them there, and not one particle of light be able to make its way through : which is contrary to; obfervation the refledion of light at the firft furface of a tranfparent body being never total in any obliquity - ^ whateViSr. _ ^ Attradiy,? * 2. As to the refledion at the fecond furface by the force fup- attradive pofed; 3 Theory. OPT Caufe of attrafHve force of the body $ this may be confidered Itefleiftion. jn two refpefts : firft, when the reflexion is total; fe- condly, when it is partial. Firft, In cafes where the refleflion is total, the caufe of it is undoubtedly that fame attradlive force by which light would be refradled in palling out of the fame body. 1 his is manifeft from that analogy which is obfervable between the reflection of light at the fecond furface, and its refradtion there. For, otherwife, wjiat can be the reafon that the total refledtion Ihould begin juft when the obliquity of the incident ray, at its arrival at the fecond furface, is fuch, that the refracted angle ought to be a right one ; or when the ray, were it not to return in refledtion, ought to pafs on parallel to the furface, without going from it ? For in this cafe it is evident, that it ought to be returned by this very power, and in fuch a manner that the angle of refledtion fliall be equal to the angle of incidence ; juft as a ftone thrown obliquely from the earth, after it is fo far turn¬ ed out of its courfe by the attradtion of the earth, as to begin to move horizontally, or parallel to the furface of the earth, is then by the fame power made to return in a curve ftmilar to that which is deferibed in its depar¬ ture from the earth, and fo falls with the fame degree of obliquity that it was thrown with. Objection. -^ut> fecondJy, As to the refledfion at the fecond fur¬ face, when it is partial; an attradlive force uniformly fpread over it, as the abettors of this hypothefis conceive it to be, can never be the caufe thereof. Becaufe it is inconceivable, that the fame force, adiing in the fame circumftances in every refpedl, can fome- times refledl the violet-coloured rays, and tranfmit the red, and at other times refledl the red and tranfmit the violet. This objedlion, however, is not well founded ; for in each colour, the refledlion takes placQ at that angle, and no other, where the refraction of that ray would make it parallel to the pofterior furface. This partial refledlion and refradiion is a great dif¬ ficulty in all the attempts which have been made to give a mechanical explanation of the phenomena of optics. It is equally a defideratum in that explana¬ tion which was propofed by Huygens, by means of the undulations of an elaftic fluid, although a vague con- fideration of undulatory motions feems to offer a very fpecious analogy. But a rigid application of the know¬ ledge we have acquired of thefe motions, will convince us that the phenomena of undulation are effentially diflimilar to the phenomena of light. The infledlion and refradiion of light, demon (Irate that light is aEled on by moving forces in a diredlion perpendicular to the furface; and it is equally demonftrable that fuch forces muft, in proper circumftances, produce refledlions pre- cifely fuch as we obferve. The only difficulty is to (how how there can be forces which produce both reflec¬ tion and refradiion, in circumftances which are fimilar. The fadl is, that fuch effedls are produced : the firft logical inference is, that .with refpedl to the light which is refledled and that which is refradled, the circumftances are not fimilar 5 and our attention fliould be diredled to the difeovery of that diflimilarity. All the phenomena of combined refledlion and refradiion fliould be examined and claffed according to their ge¬ nerality, not doubting but that thefe points of re- femblance will lead to the difeovery of their caufes. I C Sr 231 Now the experiments of M. Bouguer fhow that bodies Caufe of differ in their powers of thus feparating light by reflee- f^Aedtion. tion and refradtion. It is not therefore a general proper- v_" ' ty of light to be partly refledled and partly refradled, but a difinEhve property of different bodies ; and fince we fee that they poflefs it in different degrees, we are authorized to conclude that fome bodies may want it al- together. We may therefore expedt fome fuccefs, by confidering how bodies are affedled by light, as well as how light is affedled by bodies. Novr, in all the phe¬ nomena of the material world we find bodies connedled by mutual forces. We know no cafe w here a body A tends towards a body B, or, in common language, is at- tradled by it, without, at the fame time, the body B tending towards A. This is obferved in the phenomena of magnetifm, eledlricity, gravitation, corpufcular at- tradlion, impulfe, &c. We fliould therefore conclude from analogy, that as bodies change the motion of light, light alfo changes the motion of bodies ; and that the particles near the furface are put into vibra¬ tion by the paflage of light through among them. Suppofe a parcel of cork balls all hanging as pendu- xh^otfjec lums in a fymmetrical order, and that an eledlrified tion obviat- ball paffes through the midft of them j it is very eafyed. to ihow that it may proceed through this affemblage in various diredlions with a finuated motion, and with¬ out touching any of them, and that its ultimate direc¬ tion will have a certain inclination to its primary direc¬ tion, depending on the outline of the aflemblage, juft as is obferved in the motion of light; and, in the mean time, the cork balls will be varioufly agitated. Juft fo muft it happen to the particles of a tranfparent body, if we iuppofe that they a£l on the particles of light by mutual attradlions and repulfions. An attentive confideration of what happens here will fliow us that the fuperficial particles will be much more agitated than the reft j and thus a ftratum be produced, which, in any inftant, will a£l on thofe particles of light which are then approaching them in a manner different from that in which they will a£l on fimilarly fituated particles of light, which come into the place of the firft in the following moment, when thefe aft- ing particles of the body have (by their motion of vibration) changed their own fituation. Now it is clearly underftood, that, in all motions of vibration, fuch as the motions of pendulums, there is* a moment when the body is in its natural fituation, as when the pendulum is in the vertical line. This may happen in the fame inftant in each atom of the tranfparent body. I he particles of light which then come within the fphere of atlion may be wholly refle&ed ; in the next moment, particles of light in the very fituation of the firft may be refradled. Then will arife a feparation of light ; and as this will depend on the manner in which the particles of bodies are agitated by it during its paflage, and as this again will depend on the nature of the body, that is, on the law of adlion of thole forces which connefl the particles with each other, and with the particles of light, it will be different in different bodies. But in all bodies there will be this general refemblanee, that the feparation will be molt copious in great obliquities of incidence, which gives the repulfive forces more time for adlion, while it diminilhes the perpendicular force of the light.. Such a refemblance between the phenomena and the 232 OPT Caufe of the legitimate confequences of the afllimption (the agi- ■Iltffledion.^ ta^;on 0f parts of the body), gives us feme authority for aligning this as the caufe ; nor can the affumption be called gratuitous. To fuppofe that the particles of the tranfparent body are not thus agitated, would be a moft gratuitous contradiction of a law of nature to which w7e know no other exception. Thus the objection ftated in N° 164. is obviated, be- caufe the refleCtion'and refraCtion are not here conceived KJS as fimultaneous, but as fueceflivc. Another III. Some have ftippofed, that, by the aCtion of light -hypothefis. upon the furface of bodies, their parts are put into an undulatory motion ; and that where the furface of it is fubfiding light is tranfmitted, and in thofe places where it is riling light is reflected. But to overlook the objections which we have juft made to this theory of undulation, we have only to ob- ferve, that, were it admitted, it does not feem to ad¬ vance us a ftep farther *, for in thofe cafes, fuppofe where red is reflected and violet tranfmitted, how comes it to pafs that the red impinges only on thofe parts when the waves are riling, and the violet when they 167 are fubfiding ? Sir I New- jy. The next hypothefis is that remarkable one of thefis •^°" Hhac Newton’s fits of eafy reflection and tranfmif- ! lion, which we lhall now explain and examine. That author, as far as we can apprehend his mean¬ ing in this particular, is of opinion, that light in its ■paffage from the luminous body, is difpofed to be alter¬ nately reflected by, and tranfmitted through, any re- fraCting furface it may meet with •, that thefe difpofi- tions, which he calls fits of eafy refle&ion and eafy tranf- mijjton, return fucceflively at equal intervals •, and that they are communicated to it at its firft emiflion out of the luminous body, from which it proceeds probably by feme very fubtile and elaftic fubftance diffufed through the univerfe, and that in the following manner. As bodies falling into water, or palling through the air, pro¬ duce undulations in each, fo the rays of light may excite vibrations in this elaftic fubftance. The quicknefs of thefe vibrations depending on the elafticity of the me¬ dium (as the quieknefs of the vibrations in the air, which propagate found, depend folely on the elafticity of the air, and not upon the quicknefs of thofe in the founding body), the motion of the particles of it may be quicker than that of the rays, and therefore, when a ray at the inftant it impinges upon any furface, is in that part of a vibration of this elaftic fubftance which con- fpires with its motion, it may be eafily tranfmitted 5 and when it is in that part of a vibration which is contrary to its motion, it may be reflected. He further fuppofes, that when light falls upon the furface of a body, if it be not in a fit of eafy tranfmiflion, every ray is there put into one, fo that when they come at the other fide (for this elaftic fubftance, pervading the pores of bodies, is capable of the fame vibrations within the body as without it), the rays of one colour lhall be in a fit of eafy tranfmiflion, and thofe of another in a fit of eafy refleClion, according to the thicknefs of the body, the intervals of the fits being different in rays of a different kind. Fhis feems to account for the different colours of the bubble and thin plate of air and water ; and like- wife for the reflection of light at the fecond furface of a thicker body 5 for the light thence refleaed is alfo ob¬ served to be coloured, and to form rings according to I C S. Part I. the difterent thicknefs of the body, when not intermixed Caufe of and confounded with other light, as will appear from Keflettion. the following experiment. If a piece of glafs be ground concave on one fide and convex on the other, both its concavity and convexity having one common centre j and if a ray of light be made to pafs through a fmall hole in a piece of paper held in that common centre, and be permitted to fall on the glafs ; befides thofe rays which are regularly reflefted back to the hole again, there will be others refleCled to the paper, and form coloured rings furrounding the hole, not un¬ like thofe occafioned by the reflection of light from thin Plates; . I(r, It is ever with extreme reluctance that we venture This hypo, to call in queftion the dodtrines of Newton; but to thefis un- his theory of refledtion there is this infuperable ob-tenable' jedtion, that it explains nothing, unlefs the caufe of the fits of more eafy refledtion and tranfmiflion be held as legitimate, namely, that they are produced by the undula¬ tions of another elaftic fluid, incomparably more fubtile than light, adting upon it in the way of impulfe. The fits themfelves are matters of faff, and no way different from what we have endeavoured to account for ; but to admit this theory of them would be to tranfgrefs every rule of philofophizing. Of the Laws of Refle&ion. The fundamental law of the reflediion of light, is,Thefond* that the angle of refledtion is always equal to the angle mental law of incidence. This is found by experiment to be theofrefle<:' cafe, and befides may be demonftrated mathematicallytl0n' from the laws of impulfe in bodies perfedtly elaftic. The axiom therefore holds good in every cafe of reflec¬ tion, whether it be from plane or fpherical furfaces j and hence the feven following propofitions relating to the refledtion of light from plane and fpherical furfaces may be deduced. I. Rays of light refle&ed from a plane furface have the fame degree of inclination to one another that their refpe&ive incident ones have.—For the angle of reflec¬ tion of each ray being equal to that of its refpedlive in¬ cident one, it is evident, that each refledled ray will have the fame degree of inclination to that portion of the furface from which it is refledled that its incident one has; but it is here fuppofed, that all thofe portions of furface from which the rays are refledled, are fituated in the fame plane ; confequently the refledled rays will have the fame degree of inclination to each other that their incident ones have, from whatever part of the fur¬ face they are refledled. j^0 II. Parallel rays refle&ed from a concave furface are Laws of re- rendered converging.—To illuftrate this, let AF, CD,EB, Aedtion (fig. 1.) reprefent three parallel rays falling upon the con-from l con‘ cave furface FB, Avhofe centre is C. To the points F^J^ and B draw the lines CF, CB ; thefe being drawn from the centre, will be perpendicular to the furface at thofe cf^*L points. The incident ray CD alfo pafling through the C fig. 1. centre, will be perpendicular to the furface, and there¬ fore will return after refledlion in the fame line ; but the oblique rays AF and EB will be refledled into the lines FM and BM, fituated on the contrary fide of their refpedlive perpendiculars CF and CB. They will therefore proceed converging after refledtion towards fume point, as M, in the line CD. III. Converging rays falling on a concave furface, are. made Theory. OPT taws of made to converge more.—for, every thing remaining Kefle.inon. as ab0ve, let GF, HB, be the incident rays. Now, be- caufe thefe rays have greater angles of incidence than the parallel ones AF and EB in the foregoing cafe, their angles of reflection will alfo be larger than thofe of the others ; they will therefore converge after reflec¬ tion, fuppofe in the lines FN and BN, having their point of concourfe N farther from the point C than M, that to which the parallel rays AF and EB converged to in the foregoing cafe ; and their precife degree of convergency will be greater than that wherein they con¬ verged before reflettion. IV. Diverging rays fidling upon a concave furface, are, after refection, parallel, diverging, or converging. If they diverge from the focus of parallel rays, they then become parallel ; if from a point nearer to the furface than that, they will diverge, but in a lefs de¬ gree than before reflection ; if from a point between that and the centre, they will converge after reflection, to fome point on the contrary fide of the centre, but fi- tuated farther from it than the radiant point. If the in- cidentrays diverge from a point beyond the centre, the re- flcdted ones will converge to one on the other fide of it, but nearer to it than the radiant point; and if they di¬ verge from the centre, they will be refle&ed thither agan. 1. Let them diverge in the lines MF, MB, proceed¬ ing from the radiant point M, the focus of parallel rays j then, as the parallel rays AF and EB were refle&ed in¬ to the lines FM and BM (by Prop, ii.), thefe rays will now on the contrary be reflt ded into them. 2. Let them diverge from N, a point nearer to the furface than the focus of parallel rays, they will then be refle&ed into the diverging lines FG and BH, which the incident rays GF and HB defcribed that were ftiown to be reflected into them in the foregoing pro- pofition j but the degree of their divergency will be lefs than their divergency before reflection. 3. Let them diverge from X, a point between the focus of parallel rays and the centre ; they then make lefs angles of incidence than the rays MF and MB, which became parallel by reflection : they will confe- quently have lefs angles of reflection, and therefore pro¬ ceed converging towards fome point, as Y ; which point will always fall on the contrary fide of the centre, be- caufe a reflected ray always falls on the contrary fide of the perpendicular with refpeCt to that on which its in¬ cident one falls ; and of confequence it will be farther diftant from the centre than X. 4. If the incident rays diverge from Y, they will, after refle&ion, converge to X $ thofe which were the incident rays in the former cafe being the reflected ones in this. 5. If the incident rays proceed from the centre, they fall in with their refpeCtive perpendiculars j and for that 171 reaf°n are refle&ed thither again. 3ni a con- ^ • Parallel rays refeSied from convex furfaces are * iurface. rendered diverging.—For, let AB, GD, EF, be three Plate parallel rays falling upon the convex furface BF, whofe :Lxxxn centre is C, and let one of them, viz. GD, be perpendi¬ ng- x. cular to the furface. Through B, D, and F, the points of refle&xon, draw the lines CV, CG, and CT j which, will be perpendicular to the furface at thefe points! The incident ray GD being perpendicular to the fur¬ face, will return after refle&ion in the fame line, but the oblique ones AB and EF will return in the lines Vol. XY. Part L BK and FL, fituated on the contrary fide of their re- Laws of fpe&ive perpendiculars BV and FT. They will there- Lefledtion. fore diverge, after refle&ion, as from fome point M in the line GD produced ; and this point will be in the middle between D and C. \T. Diverging rays refelled from convex furfaces are rendered more diverging.—For, things remaining as above, let GB, GF, be the incident rays. Thefe ha- ving greater angles of incidence than the parallel ones AB and El in the preceding cafe, their angles of reflec¬ tion will alfo be greater; they will therefore diverge after refle&ion, fuppofe in the lines BP and FQ, as from fome point N, farther from C than the point M ; and the degree of their divergency will exceed their divergency before refle&ion. VII. Converging rays refected from convex furfaces are parallel, converging, or diverging.—If they tend to¬ wards the focus of parallel rays, they then become pa¬ rallel •, if to a point nearer the furface, they converge, but in a lefs degree than before refle&ion 5 if to a point between that and the centre, they will diverge after re¬ fle&ion, as from fome point on the contrary fide of the centre, but fituated farther from it than the point to which they converged ; if the incident rays converge to a point beyond thejcentre, the refle&ed ones will di-- verge as from one on the contrary fide of it, but near¬ er to it than the point to which the incident ones con¬ verged ; and if the incident rays converge towards the centre, the refle&ed ones will feem to proceed from it. 1. Let them converge in the lines KB and LF, tend¬ ing towards M, the focus of parallel rays ; then, as the parallel rays AB, EF were refle&ed into the lines BK and FL (by Prop, v.), thofe rays will nowr on the con¬ trary be refle&ed into them. 2. Let them converge in the lines PB, QF, tending towards N a point nearer the furface than the focus of parallel rays, they will then be refle&ed into the conver¬ ging lines BG and FG, in which the rays GB, GF pro¬ ceeded that were Ihown to be refle&ed into them by ther laft propofition : but the deg ree of their convergency will exceed their convergency before refle&ion. 3. Let them converge in the lines RB and SF pro¬ ceeding totvards X, a point between the focus of pa¬ rallel rays and the centre j their angles of incidence will then be lefs than thofe of the rays KB and LF, which became parallel after refle&ion : their angles of refle&ion will therefore be lefs $ on which account they mull neceffarily diverge, fuppofe in the lines BH and FI, from fome point, as Y •, which point (by Prop, iv.) will fall on the contrary fide of the centre with refpe& to X, and will be farther from it than that. 4. If the incident rays tend towards Y, the refle&ed ones will diverge as from X 5 thofe which were the in¬ cident ones in one cafe being the refle&ed ones in the other. 5. If the incident rays converge towards the centre, they coincide with their refpe&ive perpendiculars; and will therefore proceed after refle&ion as from that centre. We have already obferved, that in fome cafes there is a very great refle&ion from the fecond furface of a tranfparent body. T he degree of inclination neceflary to caufe a total refle&ion of a ray at this furface, is that which requires that the refra&ed angle (fuppofing the ray to pafs out there) fliould be equal to or greater than G g a 234 Laws of Reflection. OPT a right one ; and confequently it depends on the refrac¬ tive power of the medium through which the ray paffes, and is therefore different in different media. When a ray paffes through glafs furrounded with air, and is in¬ clined to its fecund furface under an angle of 4 2° or more, it will be wholly refle&ed there. For, as 11 is to 17 (the ratio of refraftion out of glafs into air), fo is the fine of an angle of ^2° to a fourth number that will exceed the fine of a right angle. Hence it follows, that when a ray of light arrives at the fecond furface of a tranfparent fubftance with as great or a greater degree of obliquity than that which is neceffary to make a total reflexion, it will there be all returned back to the firfl: and if it proceeds towards that with as great an obli¬ quity as it did towards the other (which it will do if the furfaces of the medium be parallel to each other), it will there be all refieaed again, &c. and will therefore never get out, but pafs from fide to fide, till it be wholly ex- tinguifiied within the body.—krom this may arife an obvibus inquiry, how it comes to pafs, that light falling very obliquely upon a glafs window from without, (hould be tranfmitted into the room. In anfwer to this it muff be confidered, that however obliquely a ray falls upon the furface of any medium whofe fides are parallel as thofe of the glafs in a window, it will fuffer fuch a degree of refra&ion in entering there, that it fhall fall upon the fecond with a lefs obliquity than that which is neceffary to caufe a total reflexion. For fince the medium be glafs : then, as 17 is to 1 x, fo is the fine of the greateft angle of incidence with which a ray can fall upon any furface to the fine of a lefs angle than that of total re- fie&ion. Therefore, if the fides of the glafs be parallel, the obliquity with which a ray falls upon the firft fur¬ face cannot be fo great, that it fhall pafs the fecond without fuffering a total refledlion there. When light paffes out of a denfer into a rarer medium, the nearer the fecond medium approaches the firft in its refraftive power, the lefs of it will be refracted in paffing from one to the other; and when their refracting powers are equal, all of it will pafs into the fecond medium. The above propofitions may be all mathematically demonltrated in the following manner : 172 The pre¬ ceding pro¬ pofitions de- monftratfed xnathemati- cally. Plate CCCLXXXII. fig- 3- Prop. I. Of the refle£tion of rays from a plane furface. When rays fall upon a plane furface, if they diverge, the focus of the reflefted rays will be at the fame di- ' fiance behind the furface, that the radiant point is be¬ fore it: if they converge, it will be at the fame diftance before the furface that the imaginary focus of the inci¬ dent rays is behind it. This propofition admits of two cafes. Case i. Of diverging renjs. Let AB, AC be two diverging rays incident on the plane furface DE, the one perpendicularly, the other obliquely : the perpendicular one AB will be refle&ed to A, proceeding as from fome point in the line AB produced ; the oblique one AC will be reflefted into fome line as CF, fo that the point G, where the line FG produced interfefts the line AB produced alfo, fiiall be at an equal diftance from the furface DE with the radiant point A. For the perpendicular CH being drawn, A CH and HCF will be the angles of.incidence and refleftion ; which being equal, their complements ACB and FCE are alfo equal; but the angle BCG is ICS. - Part I. equal to its vertical angle FCE: therefore in the tri- Laws of angles ABC and GBC the angles at C are equal, the fide BC is common, and the right angles at B are equal; therefore AB=BG : and confequently the point Gr the focus of the incident rays AB, AC, is at the fame diftance behind the furface, that the point A is before it- CasE 2. Of converging rays. This is the converie of the former cafe. For fuppo- fing FC and AB to be two converging incident rays, CA and BA will be the refle&ed ones (the angles oi incidence in the former cafe being now the angles of refleffion, and vice verfa), having the point A for their focus; but this is at an equal diftance from the re flee¬ ing furface with the point G, which in this cafe is the imaginary focus of the incident rays FC and AB. It is not here, as in the cafe of rays palling through a plane furface, where fome of the refracted rays pro¬ ceed as from one point, and fome as from another: but they all proceed after refledtion as from one and the fame point, however obliquely they may fall upon the furface ; for what is here demonftrated of the ray AC holds equally of any other, as AI, AK, &c. The cafe of parallel rays incident on a plane furface is included in this propofition : for in that cafe we are to fuppofe the radiant point infinitely diftant from the furface, and then by the propofition the focus *){ the refledled rays will be fo too : that is, the rays will be parallel after refiedlion, as they were before it. Prop. II. Of the refle&ion of parallel rays from a fpherical furface. When parallel rays are incident upon a fpherical fur¬ face, the focus of the refiedled rays will be the middle point between the centre of convexity and the lurface. This propofition admits of two cafes. Case i. Of parallel rays falling upon a convex'furface. Let AB, DH, reprefent two parallel rays incident p;gt on the convex furface BH, the one perpendicularly, the other obliquely ; and let C be the centre of convexity. Suppofe HE to be the refledled ray of the oblique one DH, proceeding as from F, a point in the line AB pro¬ duced. Through the point H draw the line Cl, which will be perpendicular to the furface at that point; and the angles DHI and IHE, being the angles of inci¬ dence and refle6tion, will be equal. But HCFrzDHI, the lines AC and DH being parallel; and CHFzrIHE, wherefore the triangle CFH is ifofceles, and confequent¬ ly CFrrFH : but fuppofing BH to vanilb, FHzzFB ; and therefore upoti this fuppofition FCzrFB ; that is, the focus of the refle&ed rays is the middle point be¬ tween the centre of convexity and the furface. Case 2. Of parallel rays falling upon a concave furface. Let AB, DH, be two parallel rays incident, the one Fig. 5. perpendicularly, the other obliquely, on the concave furface BH, whofe centre of concavity is C. Let BF and HF be the reflefted rays meeting each other in F; this will be the middle point between B and C. For drawing through C the perpendicular CH, the angles DHC=FHC, being the angles of incidence and reflec¬ tion ; but HCF=DHC its alternate angle, and there¬ fore the triangle CFH is ifofceles. Wherefore CF= FH ; but if we fuppofe BH to vanilh, FB~FH, and therefore *73 , Refleifiecl rays from Theory. OPT Laws of therefore CF=FB ; that is, the focal diftance of the Reflection reflefted rays is the middle point between the centre “ and the furface. It is here obfervable, that the farther the line DH, either in fig. 4. or 5. is taken from AB, the nearer the ■point F falls to the furface. For the farther the point H recedes from B, the greater the triangle CFH will become ; and confequently, fince it is always ifofceles and the bafe CH, being the radius, is everywhere of the fame length, the equal legs CF and FH will lengthen ; but CF cannot grow longer unlefs the point F approach towards the furface. And the farther H is removed from B, the fafter F approaches to it. This is the reafon, that whenever parallel rays are confidered as refle&ed from a fpherical furface, the diftance of the bblique ray from the perpendicular one is taken fo fmall with refpeft to the focal diftance of that furface, that without any phyfical error it may be fuppofed to vanifti. Hence it follows, that if a number of parallel rays, as AB, CD, EG, &c. fall upon a convex furface, and a fpherical jf BA, DK, the reflected rays of the incident ones AB, ver proceed proceed as from the point F, thofe of the incident from the ones CD, EG, viz. DK, GL, will proceed as from N, fame point, thofe of the incident ones EG, HI, as from O, &c. be- Fig. 6. caufe the farther the incident ones CD, EG, See. are from AB, the nearer to the furface are the points ^iff, in the line BF, from which they proceed after refleftion •, fo that properly the foci of the reflefted rays BA, DK, GL, &c. are not in the line AB produced, but in a curve line palling through the points F, N, O, &c. The fame is applicable to the cafe of parallel rays reflefled from a concave furface, as expreffed by the dotted lines on the other half of the figure, where PQ, RS, TV, are the incident rays •, QF, Sj^ the reflefted ones, interfering each other in the points X, Y, and F ; fo that the foci of thofe rays are not in the line FB, but in a curve palling through thofe points. Had the furface BH in fig. 4. or 5. been formed by the revolution of a parabola about its axis having its focus in the point F, all the rays reflered from the convex furface would have proceeded as from the point F, and thofe reflefted from the concave furface would have fallen upon it, however diftant their incident ones an'reflected might have been from each other. For in from one t^ie Parabola, all lines drawn parallel to the axis make point. angles with the tangents to the points where they cut the parabola (that is, with the furface of the parabo¬ la) equal to thofe which are made with the fame tan¬ gents by lines drawn from thence to the focus-, there¬ fore, if the incident rays deferibe thofe parallel lines, the reflefted ones will neceflarily deferibe thefe other, and fo will all proceed as from, or meet in, the fame point. Prop. III. 17S Of the refle&ion of diverging and converging rays Propor- from a fpherical furface. tional di¬ ftance of When rays fall upon any fpherical furface, if they nyVSa^v^, t^e c^ance ^ie f°cus °f the refle&ed rays «d from a ^rom the furface is to the diftance of the radiant point fpherical frorn the fame (or, if they converge, to that of the lurface. imaginary focus of the incident rays), as the diftance x74 Rays pro¬ ceeding from one point, and falling on a parabolic concave furface ICS. 235 of the focus of the reflected rays from the centre its to Laws of the diftance of the radiant point (or imaginary focus of Refleftior. the incident rays) from the fame. ^ This propofition admits of ten cafes. Case i . Of diverging rays falling upon a convex fir- face. Let RB, RD, reprefent two diverging rays flowing Fig. 7. from the point R as from a radiant, and falling the one perpendicularly, the other obliquely,' on the convex fur¬ face BD, whofe centre is C. Let DE be the reflected ray of the incident one RD ; produce ED to F, and through R draw the line RH parallel to FE till it meets CD produced in H. Then RHDzrrEDH the angle of refleftion, and RHDzrRDH the angle of incidence *, wherefore the triangle DRH is ifofceles, and DR—RH. Now the lines FD and RH being parallel, the triangles FDC and RHC are fimilar, or the fides are cut propor- tionably, and therefore FD : RH or RD—CF : CR ; but BD vaniftiing, FD and RD difter not from FB and RB : wherefore FB : RB=rCF : CR ; that is, the di¬ ftance of the focus from the furface is to the diftance of the radiant point from the fame, as the diftance of the focus from the centre is to the diftance of the radiant point from it. Case 2. Of converging rays falling upon a concave furface. Let KD and CB be the converging incident rays, having their imaginary focus in the point R, which was the radiant point in the foregoing cafe. Then as RD was in that cafe refle&ed into DE, KD will in this be reflect'd into DF ; for, finee the angles of incidence in both cafes are equal, the angles of reflexion rvill be equal alfo \ fo that F will be the focus of the refledled rays : but it was there demonftrated, that FB : RB=: CF : CR ; that is, the diftance of the focus from the furface is to the diftance (in this cafe) of the imaginary focus of the incident rays, as the diftance of the focus from the centre is to the dirtance of the imaginary focus of the incident rays from the fame. Case 3. Of converging rays falling upon a convexfur¬ face, and tending to a point between the focus of parallel rays and the centre. Let B reprefent a convex furface whofe centre is C, Fig. S. and whofe focus of parallel rays is P ; and let AB, KD, be two converging rays incident upon it, and having their imaginary focus at R, a point between P and C. Now becaufe KD tends to a point between the focus of * parallel rays and the centre, the reflefted ray DE will diverge from feme point on the other fide the centre, fuppofe F 5 as explained above. Through D draw the perpendicular CD, and produce it to H ; then will KDH=HDE, being the angles of incidence and rer fleftion, and confequently R DC — CD F too. Therefore the triangle RDF is bifedled by the line DC : where¬ fore (3 El. 6.) FD and DR, or BD vaniftiing, FB : BR—FC : CR ; that is, the diftance of the focus of the reflefled rays is to that of the imaginary focus of the incident ones, as the diftance of the former from the centre is to the diftance of the latter from the centre. Case 4. Of diverging rays falling upon a concavefur¬ face, and proceeding from a point between the focus of parallel rays and the centre. Let RB, RD, be the diverging rays incident uponp;g. 3, the concave furface BD, having their radiant point in Gga R, 236 OPT Laws of the imaginary focus of the incident rays in the pre- ^Rcfleltion. ceding cafe. Then as KD was in that cafe reflected v into DE, RD will now be refledted into DF. But we had FB : RBnrCF : CR ; that is, the diftance of the focus is to that of the radiant as the diftance of the former from the centre is to the diftance of the latter from the centre. The angles of incidence and refledlion being equal, it is evident, that if, in any cafe, the refledted ray be made the incident one, the incident will become the refledted one ; and therefore the four following cafes may be confidered refpedtively as the converfe of the four preceding 5 for in each of them the incident rays are fuppofed to coincide with the refledted ones in kthe other. Or they may be thus demonftrated independently of them. Case 5. Of converging rai/s falling upon a convex furface, and tending to a point nearer the furface than the focus of parallel rays. Fig. 7. Let ED, RB be the converging rays incident upon the convex furface BD, whofe centre is C, and principal focus P j let the imaginary focus of the incident rays be at F, a point between P and B ; and let DR be the re¬ fledted ray. From C and R draw the lines CPI, RH, the one palling through D, the other parallel to FE. Then RHD—HDE the angle of incidence. But RHD—HDR, the angle of refledtion : wherefore the triangle HDR is ifofceles, and DRr^RH. Now the lines FD and RH being parallel, the triangles FDC and RHC are fimilar •, and therefore RH or RD: FDrrCR : CF; but BD vanilhing, RD and FD coin¬ cide with RB and FB, wherefore RB : FB=CR : CFj that is, the diftance of the focus from the furface is to the diftance of the imaginary focus of the incident rays, as the diftance of the focus from the centre is to the diftance of the imaginary focus of the incident rays from the centre. Case 6. Of diverging rays falling upon a concave furface, and proceeding from a point between the focus of parallel rays and the furface. Let FD and FB be two rays diverging from the point F, which was the imaginary focus of the incident rays in the preceding cafei Then as ED was in that cafe refledted into DR, FD will be refledted into DK (for the reafon mentioned in cafe 2.), fo that the re¬ fledted ray will proceed as from the point R: but it was demonftrated in cafe 5. that RB : FBzrCR : CF; that is, the diftance of the focus from the furface is to that of the radiant from the furface, as the diftance of the former from the centre is to that of the latter from the centre. Case 7. Of converging rays falling upon a convex furface, and tending towards a point beyond the centre. Hg. 8. Let AB, ED be the incident rays tending to F, a point beyond the centre C, and let DK be the refledted rav of the incident one ED. Thenbecaufe the incident ray ED tends to a point beyond the centre, the refledted ray DK will proceed as from one on the contrary fide, fuppofe R *, fee Prop. vii. Through D draw the perpen¬ dicular CD, and produce it to PL Then will EDHrr HDK, being the angles of incidence and refledtion •, but CDF~( DR, being their verticals: confequently the angle FDR is bifedted by the line CD : wherefore RD : DF, or (3 Ekm. 6 ) BD vaniftiing, RB : BF= RC : CF that is,, the diftance of the focus of the re* I c s. Part I, fledted rays is to that of the imaginary focus of the Laws of incident rays, as the diftance of the former from the ^iefle&iop, centre is to the diftance of the latter from the centre. V~^J Case 8. Of diverging rays falling upon a concave fur- face, and proceeding from a point beyond the centre. Let FB, FD be the incident rays radiating from F, the imaginary focus of the incident rays in the cafe. Then as ED was in that cafe refledted into DK, FD will now be refledted into DR j fo that R will be the focus of the refledted rays. But it was demonftrated in the cafe 7. that RB : P’BzrRC : CF ; that is, the di¬ ftance of the focus of the refledted rays from the furface is to the diftance of the radiant from the furface, as the diftance of the focus of the refledted rays from the centre is to the diftance of the radiant from the centre. The two remaining cafes may be confidered as the converfe of thofe under Prop. ii. (p. 234.), becaufe the incident rays in thefe are the refledted ones in them •, or they may be demonftrated in the fame manner with the preceding, as follows. Case 9. Converging raysfalling upon a convexfurface, and tending to the focus of parallel rays, become parallel after refletiion. Let ED, RB reprefent two converging rays incident Pbte on the convex furface BD, and tending towards F, eccfiLXXXn* which we ftiall now fuppofe to be the focus of parallel r rays; and let DR be the refledted ray, and C the centre of convexity of the refledting furface. Through C draw CD, and produce it to H, drawing RH parallel to ED produced to F. Now it has been demonftrated (cafe 5. where the incident rays are fuppofed to tend to the point F), that RB : P’B=:RC : CF •, but F in this cafe being fuppofed to be the focus of parallel rays, it is the middle point between C and B (by Prop, ii.) and there¬ fore FB=FC, confequently RBzz:RC ; which can only be upon the fuppofition that R is at an infinite diftance from B } that is, that the refledted rays BR and DR be parallel. Case 10. Diverging rays falling upon a concave fur¬ face, and proceeding from the focus of parallel rays, be¬ come parallel after refleElion. Let RD, RB be two diverging rays incident upon Fig. L the concave furface BD, as fuppofed in cafe 4. where it was demonftrated that FB : RBrrCF : CR. But in the prefent cafe RB:=CR, becaufe R is fuppofed to be the focus of parallel rays j therefore FBrrFC j which cannot be unlefs F be taken at an infinite diftance from B; that is, unlefs the refledted rays BF and DF be parallel. It may here be obferved that in the cafe of diverging Fig. 9. rays falling upon a convex furface, the farther the point D is taken from B, the nearer the point F, the focus of the refledted rays, approaches to B, while the radiant point R remains the fame. For it is evident from the Fig. ie. curvature of a circle, that the point D may be taken fo far from B, that the refledted ray DE {hall proceed as from F, G, H, or even from B, or from any point between B and R ; and the farther it is taken from B, the fafter the point from which it proceeds approaches towards R: as will appear if we draw feveral incident rays with their re- fpedtive refledted ones, in fuch a manner that the angles of refledtu n may be equal to their refpt dtive angles of inci¬ dence, as is done in the figure. The like is applicable to any of the other cafes of diverging and converging rays in¬ cident upon a fpherical furface. This is the reafon, that, when rays are confidered as refledted from a fpherical furfaccj Theory. O P T I Laws of Refledfion. fig- 7- Fig 8. 176 Method of finding the focal di- ftance of rays reflec¬ ted from a convex fur- face. furface, the diftance of the oblique rays from the per- | pendicular one is taken fo (mail, that it may be fuppofed to vanifh. From this it follows, that if a number of diverging rays are incident upon the convex furface BD at the feveral points B, D, D, &c. they will not proceed after refle&ion as from any point in the line RB produced, but as from a curve line palling through the feveral. points F,/,/, &c. Had the curve BD been a hyperbola, having its foci in R and F, then R being the radiant (or the imaginary focus of incident rays), F would have been the focus of the reflefled ones, and vice verfa, however dill ant the points B and D might be taken from each other. In like manner, had the curve BD been an ellipfe having its foci in F and R, the one of thefe being made the radiant (or imaginary focus of incident rays), the other would have been the focus of refledled ones, and vice verfa. For both in the hyperbola and ellipfe, lines drawn from each of their foci through any point make equal angles with the tangent to that point. Therefore, if the incident rays proceed to or from one of their foci, the refledted ones will all proceed as from or to the other focus. Therefore, in order that diverging or con¬ verging rays may be accurately reflected to or from a point, the reflefting furface mull be formed by the revo¬ lution of an hyperbola about its longer axis, when the incident rays are fuch, that their radiant or imaginary focus of incident rays (ball fall on one fide of the fur¬ face, and the focus of the refle&ed ones on the other *, when they are both to fall on the fame fide, it mull be formed by the revolution of an ellipfe about its longer axis. However, as fpherical furfaces are more ealily formed, than thofe which are generated by the revolu¬ tion of any of the conic fe&ions about their axes, the latter are very rarely ufed. Now, becaufe the focal diftance of rays reflected from a fpherical furface cannot be found by the analogy laid down in the third propoiition, without making ufe of the quantity fought •, wre (hall here give an example whereby the method of doing it in all others will readily appear. Problem. Let it be required to find the focal diftance of diverging rays incident upon a convex furface, whofe radius of convexity is five parts, and the diftance of the radiant from the furface is 20. Call x the focal diftance fought j then will the di¬ ftance of the focus from the centre be 5—x, and that of the radiant from the fame 25, therefore by Prop. iii. we have the following proportion, x : 20=5—x : 25; and multiplying extremes together and means together, we have 25 x=ioo—20#, or #=i4eja. If it Ihould happen in any cafe that the value of x is a negative quantity, the focal point mart then be taken on the contrary fide of the furface to that on which it was fuppofed it would fall in dating the problem. Becaufe it was obferved in the preceding feftion, that difterent incident rays, though tending to or from one point, would after refra6lion proceed to or from different points, a method was there given of determining the diftinft point which each feparate ray entering a fpheri- eal furface converges to, or diverges from, after reffac- Plate cccLxatxir, S-e. a. C S. 237 tion : the fame has been obferved here with regard to Appearanc® rays reiledted from a fphericai lurface (ifee cafe 2. and °* cafe 10.) But the method of determining the diftindl16^, ^^ e' point to or from which any incident ray proceeds after . " ' ■ refledlion, is much more fimple. It is only neceffary to draw the refledled ray fuch, that the angle of refiedtion may be equal to the angle of incidence, which will determine the point it proceeds to or from in any cafe whatever. Sect. VIII. Of the Appearance of Bodies feen by Light rcfeciedfrom plane and fpherical Surfaces. Whatever has been faid concerning the appearance of bodies feen through lenfes, by refradted light, refpedls alfo the appearance of bodies feen by reftedlion. But, befides thefe, there is one thing peculiar to images by refledtion, viz. that each point in the reprefentation of an objedf made by refledtion appears fituated fomewhere in a right line that paffes though its correfpondent point in the objedl, and is perpendicular to the refledting furface. The truth of this appears fufficiently from the pro- pofitions formerly laid down: in each of which, rays flowing from any radiant point, are fliown to proceed after refledlion to or from fome point in a line that paffes through the radiant point, and is perpendicular to the refledling furface. For inllance (fig. 1.) rays flow¬ ing from Y are colledled in X, a point in the perpendi¬ cular CD, which, being produced, paffes through Y 5 again (fig. 2.), rays flowing from G, proceed, after re¬ fledlion, as from N, a point in the perpendicular CD, which being produced, paffes through G. This obfervation, however, except where an objedt is feen by refledlion from a plain furface, relates only to thofe cafes where the reprefentation is made by means of fuch rays as fall upon the refledling furface with a very fmall degree of obliquity 5 becaufe fuch as fall at a confiderable diftance from the perpendicular, do not proceed after refledlion as from any point in that perpendicular, but as from other points fituated in a cer¬ tain curve, on which account thefe rays are negledled, as making an indiftindl and deformed reprefentation. .And therefore it is to be remembered, that however the fituation of the eye with refpedl to the objedl and refledl¬ ing furface may be reprefented in the following figures, it is to be fuppofed as fituated in fuch a manner with re¬ fpedl to the objedl, that rays flowing from thence and entering it after refledlion, may be fuch only as fall with a very fmall degree of obliquity upon the furfaee ; that is, the eye mull be fuppofed to be placed almoft diredlly behind the objedt, or between it and the refledl¬ ing furface. The reafon why it is not always fo placed, is only to avoid confufion in the figures. I. When an objccl is feen by refledlion from a plane furface, the image of it appears at the fame difance behind the furface that the objedl is before it, of the fame magnitude, and diredlly oppq/ite to it. To explain this, let AB reprefent an objedl feen by The ap- refledlion from the plane furface SV and let the rayspearance of AF, AG, be fo inclined to the furface, that they lhallre" enter an eye at H after xefledlion *, and let AE be Per~fromep;an# pendicular to the furface : then, by the obfervation jufl furfaces< mentioned, the point A will appear in fome part of the Fig. io»- line AE produced, fuppofe I j that is, the oblique rays AF 238 OPT Appearance .Al? and AG will proceed after refle&ion as from that fcvn^Ke lKI‘nt '? and further, becaufe the refle61ed rays FH, GK, Lfledtion " liave the ^ame degree of inclination to one another from differ-that their incident ones have, that point muft neceffarily ent Sur- be at the fame diftance from the furfaee that the point . faces- A is 5 the reprefentation therefore of the point A will v be at the fame diftance from the furface that the point itfelf is before it, and directly oppofite to it : confe- quently, fince the like may be fliown of any other point B, the whole image IM will appear at the fame diftance behind the furface that the objedt is before it, and diredtly oppofite to it and becaufe the lines AI, BM, perpendicular to the plain furface, are parallel to each other, the image will alfo be of the fame magnitude with t„3 the objedt. From/con- II. When an objeR is feen by reJleRionfrom a convex vex fur- furface, its image appears nearer to the furface, and lefs -facea. than the object. Fig. 12. Let AB reprefent the objedt, SV a refledting furface whofe centre of convexity is C : and let the rays AF, AG, be fo inclined to the furface, that after reftedtion from it, they fliall enter the eye at H : and let AE be perpendicular to the furface ; then will the oblique rays AF, AG, proceed after refledtion as from fome point in the line AE produced, fuppofe from I $ which point, becaufe the reftedted rays will diverge more than the in¬ cident ones, muft; be nearer to the furface than the point A. And lince the fame is alfo true of the rays which From con¬ cave fur- faces. Wig. 13. flow from any other B, the reprefentation IM will be nearer to the furface than the objedt ; and becaufe it is terminated by the perpendiculars AE and BF, which incline to each other, as concurring at the centre, it will alfo appear lefs. III. When an objeR is feen bij refeR ion from a con¬ cave furface, the reprefentation of it is various, both with regard to its magnitude and fituation, according as the difance of the objeR from the refleRing furface is greater or lefs. 1. When the objedt is nearer to the furface than its principal focus, the image falls on the oppofite fide of the furface, is more diftant from it, and larger than the objedt. Thus let AB be the objedt, SV the reftedting fur¬ face, F the principal focus, and C its centre. Through A and B, the extremities of the objedt, draw the lines CE, Of, which will be perpendicular to the furface j and let the rays AR, AG, be incident upon fuch points of it that they {hall be refledted into an eye at H. Now, becaufe the radiant points A and B are nearer the fur¬ face than the principal focus F, the refledted rays will diverge, and therefore proceed as from fome points on the oppofite fide of the furface •, which points, by the obfervation laid down at the beginning of this fedtion, will be in the perpendiculars AE, BE, produced, fup¬ pofe in I and M : but they will diverge in a lefs degree than their incident ones $ and therefore the faid points will be farther from the furface than the points A and B. The image therefore will be on the oppofite fide of the furface with refpedt to the objedl : it will be more diftant than it *, and confequently, being terminated by the perpendiculars Cl and CM, it will alfo be larger. 2. When the objedl is placed in the principal focus, the refledted rays enter the eye parallel; in which cafe the image ought to appear at an infinite diftance behind ICS. Part I. the refledting furface : but the reprefentation of it, for Appearance the reafons given in the foregoing cafe, being large and .ot bodies diftindt, wre do not reckon it much farther from the fur- iLefln f face than the image. e 10,1 horn differ. 3. When the objedt is placed between the principal ent Sur- focus and the centre, the image falls on the oppofite fide ^ace». of the centre, is larger than the objedt, and in an invert- J ed pofition. P|at Thus let ABbe the objedt, SV the refledting furface, ccclxsxii! F its principal focus, and C its centre. Through A %■ 14. and B, draw the lines CE and CN, which will be per¬ pendicular to the furface ; and let AR, AG, be a pen¬ cil of rays flowing from A. Thefe rays proceeding from a point beyond the principal focus, will after re¬ fledtion converge towards fome point on the oppofite fide the centre, which will fall upon the perpendicular EC produced, but at a greater diftance from C than the radiant A from which they diverged. For the fame reafon, rays flowing from B will converge to a point in the perpendicular NC produced, which fhall be farther from C than the point B ; whence it is evident, that the image IM is larger than the objedl; AB, that it falls on the contrary fide of the centre, and that their pofitions are inverted with refpedl to each other. 4. If the objedt be placed beyond the centre of con¬ vexity, the image is then formed between the centre and the focus of parallel rays, is lefs than the objedt, and its pofition is inverted. This propofition is the converfe of the preceding *, for as in that cafe rays proceeding from A were refledted to I, and from B to M 5 fo rays flowing from I and M will be refledted to A and B : if therefore an objedt be fuppofed to be fituated beyond the centre in IM, the image of it will be formed in AB between that and the focus of parallel rays, will be lefs than the objedt, and inverted. 5. If the middle of the objedt be placed in the centre of convexity of the refiedting furface, the objedt and its image will be coincident ; but the image will be in¬ verted with refpedt to the objedt. That the place of the image and the objedt Ihould be the fame in this cafe requires little explication ; for the middle of the objedt being in the centre, rays flow¬ ing from it will fall perpendicularly upon the furface, and therefore neceflarily return thither again j fo that the middle of the image will be coincident with the middle of the objedt. But that the image fhould be in¬ verted is perhaps not fo clear. To explain this, let AB Fig. 15. be the objedt, having its middle point C in the centre of the retledling furface from SV ; through the centre and the point R draw the line CR, which will be per¬ pendicular to the refledting furface ; join the points AR and BR, and let AR reprefent a ray flowing from A ; this will be refledted into RB : for C being the middle point between A and B, the angle ARC—CRB ; and a ray from B will likewife be reflected to A ; and there¬ fore the pofition of the image will be inverted with re¬ fpedt to that of the objedt. In this propofition it is to be fuppofed, that the objedt AB is fo fituated with refpedt to the refledting furface, that the angle ACR may be right; for other- wife the angles ARC and BRC will not be equal, and part of the image only will therefore fall upon the ob- jedt. 6. If Theory. OPT Appearance 6. If in any of the three laft cafes, in each of Ot Bodies which th» image is formed on the fame fide of the re- fleaL 'fle&ing furface w3th the objeft, the eye be fituated far- from differ- ther from the furface than the place where the image entSur- falls, the rays of each pencil, eroding each other m as the furfaces AB, BC, an obieft at D may be 21' feen by an eye at E, after one refleiElion at F, in the line EF produced \ after two refleftions, the firft at G, the fecond at H, in the line EH produced ; and, alfo, after one reflection made at A, in the line EA produced. Fig. 2a. 2. If the furfaces be parallel, as AB, CD, (fig. 22.), and the objeCt be placed at E and the eye at F, the ob~ jeCt will appear multiplied an infinite number of times : thus it may be feen in the line FG produced, after one reflection at G ; in the line FH produced, after two re¬ flexions, the firft at I, the fecond at H •, and alfo in FP produced, after feveral fucceflive reflections of the ray EL, at the points L, M, N, O, and P : and fo on in infinitum. But the greater the number of reflections are, the weaker their reprefentation will be. SECT. IX. Of the apparent Place, Diflance, Magnitude, _ and Motion of (JbjeSls. It had in general been taken for granted, that the place to which the eye refers any vifible objeCl feen by reflection or refraClion, is that in which the vi- App.rer.t fual rays meet a perpendicular from the objedt upon P|a'e> the reflecting or refraCting plane. But this method 0L.itns.^ of judging of the place of objeCfs was called in quef- tion by Dr Barrow, who contended that the argu¬ ments brought in favour of the opinion were not con- ^ clufive. Thefe arguments are, that the images of Dr Bar- objeCts appeared ftraight in a plane mirror, but curved row’.s theo. in a convex or concave one : that a ftraight thread,l") re‘pt' The moft; general, and frequently the moft certain means of judging of the diftance of objedls is, he fays, by the angle made by the optic axis. For our two eyes are like two different Rations, by the affiftance of which diftances are taken *, and this is the reafon wffiy thofe perfons who are blind of one eye, fo frequently mils their marks in pouring liquor into a glafs, fnuffing a candle, and fueh other aftions as require that the di¬ ftance be exaiftly diftinguiffied. To be convinced of the utility of this method of judging of the diftance of objefts, he dire61s us to fufpend a ring in a thread, fo that its fide may be towards us, and the hole in it to the right and left hand ; and taking a fmall rod, crooked at the end, retire from the ring two or three paces and having 'with one hand covered one of our eyes, to endeavour with the other to pafs the crooked end of the rod through the ring. This, fays he, appears very eafy ; and yet, upon trial, perhaps once in 100 times •we flrall not fucceed, efpecially if we move the rod a little quickly. The ufe of this fecond method of judging of diftances Dechales limited to 120 feet; beyond which, be fays, we are not fenfible of any difference in the angle of the optic axis. A third method of judging of the diftance of objefls^. confifts in their apparent magnitudes, on which fo much ftrefs was laid by Dr Smith. From this change in the magnitude. Theory. OPT Apparent magnitude of the image upon the retina, we eafily place, &c. judge of the diftance of objeds, as often as we are other- of ohjerts.^ acquainted with their magnitude $ but as often as ¥ we are ignorant of the real magnitude of bodies, we can never, from their apparent magnitude, form any judge¬ ment of their diftance. Hence we may fee why we are fo frequently deceived in our eftimates of diftance, by any extraordinary mag¬ nitudes of objeds fecn at the end of it ; as, in travelling towards a large city, or a caftle, or a cathedral church, or a mountain larger than common, we fancy them to be nearer than they really are. This alfo is the reafon why animals, and little objefts, feen in valleys, conti¬ guous to large mountains, .appear exceedingly fmall. For we think the mountain nearer to us than if it were fmaller 5 and we Humid not be furprifed at the fmall- nefs of the neighbouring animals, if we thought them farther oft'. For the fame reafon, we think them ex¬ ceedingly fmall, when they are placed upon the top of a mountain, or a large building ; which appear nearer to us than they really are, on account of their extraor¬ dinary fize. Dr Jurin accounts for our imagining objeds, when feen from a high building, to be fmaller than they are, building appear fmalier than they are. 1S9 Why ob- je.fts feen ^ from a highand fmalier than we fancy them to be when we view them at the fame diftance on level ground. It is, fays he, becaufe we have no diftind idea of diftance in that diredion, and therefore judge of things by their pidures upon the eye only ; but cuftom will enable us to judge rightly even in this cafe. Let a boy, fays he, who has never been upon any high building, go to the top of a lofty fpire, and look down into the ftreet ; the objeds feen there, as men and horfes, will appear fo fmall as greatly to iur- prife him. But 10 or 20 years after, if in the mean time he has ufed himfelf now and then to look down from that and other great heights, he will no longer find the fame objeds to appear fo fmall. And if he were to view the fame objeds from fueh heights as fre¬ quently as he fees them upon the fame level with himfelf in the ftreets, he fuppofes that they would ap¬ pear to him juft of the fame magnitude from the top of the fpire, as they do from a window one ftory high. For this reafon it is, that ftatues placed upon very high buildings ought to be made of a larger fize than thofe which are feen at a nearer diftance j becaufe all perfons, except architeds, are apt to imagine the height of fuch buildings to be much lefs than it really is. The fourth method by which Dr Porterfield fays that we judge of the diftance of objeds, is the force with which their colour*ftrikcs upon our eyes. For if we be affured that two objeds are of a fimilar and like colour, and that one appears more bright and lively than the other, we judge that the brighter objed is the nearer of the two. The fifth method confifts in the different appearance of the fmall parts of objeds. When thefe parts appear diftind, we judge that the objed is near-, but when they appear confufed, or when they do not appear at all, we reckon the objed to be at a greater diftance. For the image of any objed, or part of an objed, dimi- nilhes as its diftance increafes. The fixth and laft method by wjiich we judge of the diftance of .objeds is, that the eye does not repre- I C S, 243 fent to our mind one objed alone, but at the fame Appaient time all thofe that are placed betwixt us and the prin- cipal objed, whofe diftance we are conftdering j and ° the more this diftance is divided into feparate and di¬ ftind parts, the greater it appears to be. For this reafon, diftanees upon uneven furfaces appear lefs than upon a plane : for the inequalities of the furfaces, fuch as hills, and holes, and rivers, that lie low and out of fight, either do not appear, or hinder the parts that lie behind them from appearing j and fo the whole ap¬ parent diftance is diminithed by the parts that do not appear in it. This is the reafon that the banks of a river appear contiguous to a diftant eye, when the river is low and not feen. jpo Dr Porterfield very well explains feveral fallacies in Several fab vifion which depend upon our miftaking the diftances of lacies V1" objeds. Of this kind, he fays, is the appearance of^j -. ^j parallel lines, and long villas confifting of parallel rows of trees ; for they feem to converge more and more as they are farther extended from the eye. The reafon of this, he fays, is becaufe the apparent magnitudes of their perpendicular intervals are perpetually diminifti- ing> while, at the fame time, we miftake their diftance. Hence we may fee why, when two parallel rows of trees ftand upon an afeent, whereby the more remote parts appear farther off than they really are, becaufe the line that meafures the length of the viftas now ap¬ pears under a greater angle than when it was horizontal, the trees, in fuch a cafe, will* feem to converge lefs, and fometimes, inftead of converging, they will be thought to diverge. For the fame reafon that a long vifta appears to converge more and more the farther it is extended from the eye, the remoter parts of a horizontal walk or a long floor will appear to afeend gradually ; and objeds placed upon it, the more remote they are the higher they will appear, till the laft be feen on a level with the eye ; whereas the ceiling of a long gallery appears to defeend towards a horizontal line, drawn from the eye of the fpedator. For this reafon, alfo, the furface of the fea, feen from an eminence, feems to rife higher and higher the farther wre look ; and the upper parts of high buildings feem to ftoop, or incline forwards over the eye below, becaufe they feem to ap¬ proach towards a vertical line proceeding from the fpedator’s eye ; fo that ftatues on the top of fuch build¬ ings, in order to appear upright, mult recline, or bend backwards. Dr Porterfield alfo ftiows the reafon why a windmill, feen from a great diftance, is fometimes imagined to move the contrary way from what it really does, by our taking the nearer end of the fail for the more re¬ mote. The uncertainty we fometimes find in the courfe of the motion of a branch of lighted candles, turned round at a diftance, is owing, he fays, to the fame caufe $ as alfo our fometimes miftaking a convex for a concave furface, more efpecially in viewing leals and imprelfions with a convex glafs or a double mi- crofcope ; and laftly, that, upon coming in a dark night into a ftreet, in which there is but one row of lamps, tve often miftake the fide of the ftreet they are on. Far more light was thrown upon this curious fubject by M. Bouguer. The proper method of drawing the appearance of H h 2 two 244 OPT Apparent two rows of trees that {hall appear parallel to the eye, place, &c. js a probiem vvhich has exercifed the ingenuity of fe- ofobje s. veraj pbilofophers and mathematicians. That the ap- rpt parent magnitude of objects decreafes with the angle Great light under which they are feen, has always been acknow- thrownup- lodged. It is alfo acknowledged, that it is only by ‘edHj' ^M* cuft°m an^ experience that we learn to form a judge- £ouguer. ment both of magnitudes and diftances. But in the ap¬ plication of thefe maxims to the above-mentioned pro¬ blem, all perfons, before M. Bouguer, made ufe of the real diftance inftead of the apparent one j by which only the mind can form its judgment. And it is ma- nifefl:, that, if any circumftances contribute to make the diftance appear otherwife than it is in reality, the ap¬ parent magnitude of the objeft will be affected by it; for the fame reafon, that, if the magnitude be mifap- prehended, the idea of the diftance will vary. For want of attending to this diftin&ion, Tacquet pretended to demonftrate, that nothing can give the idea of two parallel lines (rows of trees for inftance) to an eye fituated at one of their extremities, but two hy¬ perbolical curves, turned the contrary way j and M. Va- rignon maintained, that in order to make a vifta appear of the fame width, it muft be made narrow, inftead of wider, as it recedes from the eye. M. Bouguer obferves, that very great diftances, and thofe that are eonliderably lefs than they, make nearly the fame impreflion upon the eye. We, therefore, al¬ ways imagine great diftances to be lefs than they are $ and for this reafon the ground plan of a long vifta al¬ ways appeass to rife. The vifual rays come in a deter¬ minate dire&ion j but as we imagine that they termi¬ nate fooner than they do, we neceffarily conceive that the place from which they iffue is elevated. Every Phte large plane, therefore, as AB, viewed by an eye at O, ccclxxxiv feem t0 ije jn fucb a direction as A and confe- 2' quently lines, in order to appear truly parallel on the plane AB, muft be drawn fo as that they would appear parallel on the plane A d, and be from thence projected to the plane AB. To determine the inclination of the apparent ground- plan Ad to the true ground-plan AB, our ingenious author diredls us to draw upon a piece of level ground two ftraight lines of a fufftcient length (for which pur- • pofe lines fattened to fmall flicks are very convenient), making an angle of 3 or 4 degrees with one another. Then a perfon, placing himfelf within the angle, with his back towards the angular point, muft walk back¬ wards and forwards till he can fancy the lines to be parallel. In this fituation, a line drawn from the point of the angle through the place of his eye, will contain the fame angle with the true ground-plan which tins does with the apparent one. M. Bouguer then (hows other more geometrical methods of determining this inclination; and fays j that by thefe means he has often found it to be 4 or 5 degrees, though fometimes only 2 or 2| degrees. The determination of this angle, he obferves, is variable; depending upon the manner in which the ground is il¬ luminated and the intenfity of the light. The colour of the foil is alfo not without its influence, as well as the particular conformation of the eye, by which it is more or lefs affefted by the fame degree of light, and alfo the part of the eye on which the objeft is painted. When, by a flight motion of his head, he contrived, 3 I C S. Part I. that certain parts of the foil, the image of vvhich fell to- Apparent wards the bottom of his eye, ftiould fall towards the top P^ace. &c. of the retina, he always thought that this apparent in- ,of obj^3. clination became a little greater. w But what is very remarkable, is, that if he look to¬ wards a riling ground, the difference between the ap¬ parent ground-plan and the true one will be much more confiderable, fo that they will fometimes make an angle of 25 or 30 degrees. Of this he had made frequent ob- fervations. Mountains, he fays, begin to be inacceflible when their fides make an angle from 35 or 37 degrees with the horizon, as then it is not poflible to climb them but by means of ftones or ftirubs, to ferve as fteps to fix the feet on. In thefe cafes, both he and his companions always agreed that the apparent inclination of the fide of the mountain was 60 or 70 degrees. Thefe deceptions are reprefented in fig. 3. in which, CCCLXXXi, when the ground-plan AM, or AN, is much inclined, fig. 3, the apparent ground-plan A m, or A n, makes a very large angle with it. On the contrary, if the ground dips below the level, the inclination of the apparent to the true ground plan diminifties, till, at a certain degree of the flope, it becomes nothing at all; the two plans AP and Ap being the fame, fo that parallel lines drawn upon them would always appear fo. If the inclination below the horizon is carried beyond the fituation AP, the error will increafe ; and what is very remarkable, it will be on the contrary fide j the apparent plan A r being always below the true plan AR, fo that if a per¬ fon would draw upon the plan AR lines that {hall ap¬ pear parallel to the eye, they muft be drawn conver¬ ging, and not diverging, as is ufual on the level ground j becaufe they muft be the projections of two lines ima¬ gined to be parallel, on the plan A r, which is more in¬ clined to the horizon than AR. Thefe remarks, he obferves, are applicable to differ¬ ent planes expofed to the eye at the fame time. For if BH, fig. 4. be the front of a building, at the diftance pjg. ^ of AB from the eye, it will be reduced in appearance to the diftance A £ ; and the front of the building will be b 7i, rather inclined towards the fpeClator, unlefs the di¬ ftance be inconfiderable. After making a great number of obfervations upon this fubjedt, our author concludes, that when a man ftands upon a level plane, it does not feem to rife fenfibly but at fome diftance from him. The apparent plane, therefore, has a curvature in it, at that diftance, the form of which is not very eafy to determine $ fo that a man {landing upon a level plane, of infinite extent, will imagine that he ftands in the centre of a bafon. This is alfo, in fome meafure, the cafe with a perfon Handing upon the level of the fea. He concludes with obferving, that there is no diffi¬ culty in drawing lines according to thefe rules, fo as to have any given effeCt upon the eye, except when fome parts of the profpeft are very near the fpeftator, and others very diftant from him, becaufe, in this cafe, re¬ gard muft be had to the conical or conoidal figure of a furface. A right line pafling at a fmall diftance from the obferver, and below the level of his eye, in that cafe almoft always appears fenfibly curved at a certain di¬ ftance from the eye j and almoft all figures in this cafe are fubje6t to fome complicated optical alteration to which the rules of perfpedive have not as yet been ex¬ tended. If a circle be drawn near our feet, and within that Theory. OPT Apparent that part of the ground which appears level to us, it place, &c. always appear to be a circle, and at a very confi- of objects, jjgj.abjg diftance it will appear an ellipfe j but between thefe two fituations, it will not appear to be either the one or the other, but will be like one of thofe ovals of iDefcartes, which is more curved on one of its lides than the other. On thefe principles a parterre, which appears dif- torted when it is feen in a low fituation, appears per¬ fectly regular when it is viewed from a balcony or any other eminence. Still, however, the apparent ir¬ regularity takes place at a greater diitance, while the part that is near the fpeCtator is exempt from it. If fig-5‘ AB, fig. 5. be the ground-plan, and A a be a per¬ pendicular, under the eye, the higher it is fituated, at O, to the greater diitance will T, the place at which the plane begins to have an apparent afcent along T b, IJ)2 be removed. Vifible mo- All the varieties that can occur with refpeCt to the tion of ob- vilible motion of objeCts, are thus fuccinCtly fummed jeifts. Up ky. j)r porterfield under eleven heads. 1. An objeCt moving very fwiftly is not feen, unlefs it be very luminous. Thus a cannon ball is not feen if it is viewed tranfverfely : but if it be viewed according to the line it defcribes, it may be feen, becaufe its pic¬ ture continues long on the fame place of the retina 5 which, therefore, receives a more fenfible impreflion from the objeCt. 2. A live coal fwung brifkly round in a circle ap¬ pears a continued circle of fire, becaufe the impreflions made on the retina by light, being of a vibrating, and confequently of a lading nature, do not prefently perilh, but continue till the coal performs its whole circuit, and returns again to its former place. 3. If two objeCts, unequally diftant from the eye, move with equal velocity, the more remote one will appear the flower j or, if their celerities be proportion¬ al to their diftances, they will appear equally fwift. 4. If two objeCts, unequally diftant from the eye, move with unequal velocities in the fame direction, their apparent velocities are in a ratio compounded of the direCt ratio of their true velocities, and the reciprocal one of their diftances from the eye. 5. A vifible objeCt moving with any velocity appears to be at reft, if the fpace defcribed in the interval of one fecond be imperceptible at the diftance of the eye. Hence it is that a near objeCt moving very flowly, as the index of a clock, or a remote one very fwiftly, as a planet, feems to be at reft. 6. An objeCt moving with any degree of velocity will appear at reft, if the fpace it runs over in a fe¬ cond of time be to its diftance from the eye as 1 to 1400. 7. The eye proceeding ftraight from one place to another, a lateral objeCt, not too far off, whether on the right or left, will feem to move the contrary way. 8. The eye proceeding ftraight from one place to another, and being fenfible of its motion, diftant objeCts will feem to move the fame way, and with the fame ve¬ locity. Thus, to a perfon running eaftwards, the moon on his right hand appears to move the fame way, and with equal fwiftne.fs j for, on account of its diftance, its image continues fixed upon the fame place of the retina, from whence we imagine that the objeCt moves along with the eye. I C S. 24s 9. If the eye and the objeCt move both the fame way, Apparent only the eye much fvvifter than the objeCt, the laft will p!30.6: ^c‘ appear to go backwards,. ‘ 10. If two or more objeCts move with the fame velo¬ city, and a third remain at reft, the moveable ones will appear fixed, and the quiefcent one in motion the con¬ trary way. Thus when clouds move very fwiftly, their parts feem to preferve their fituation, and the moon to move the contrary way. 11. If the eye be moved with great velocity, lateral objeCts at reft appear to move the contrary way. Thus to a perfon fitting in a coach, and riding brifldy through a wood, the trees feem to retire the contrary way ; and to people in a fliip, &c. the ftiores feem to recede. At the conclufion of thefe obfervations, Dr Porter- Dr Porter¬ field endeavours to explain another phenomenon of mo- field’s ac¬ tion, which, though common and well known, had not been explained in a fatisfaftory manner. It is this : Ifpearingto a perfon turns fwiftly round, without changing his move to a place, all objeCls about will feem to move round in agid‘lyPer- circle tlie contrary way 5 and this deception continues ^ not only while the perfon himfelf moves round, but, j^both at which is more furprifing, it alfo continues for fome time reft, after he ceafes to move, when the eye, as well as the objeCt, is at abfolute reft. The reafon why objeCts appear to move round the contrary way, when the eye turns round, is not fo diffi¬ cult to explain : for though, properly fpeaking, motion is not feen, as not being in itfelf the immediate objeCt of fight; yet by the fight we eafily know when the image changes its place on the retina, and thence con¬ clude that either the objeCt, the eye, or both, are moved. But by the fight alone we can never determine howr far this motion belongs to the objeCt, how far to the eye, or how far to both. If we imagine the eye at reft, we afcribe the whole motion to the objeCt, though it be tru¬ ly at reft. If we imagine the objeCt at reft, we afcribe the whole motion to the eye, though it belongs entire¬ ly to the objeCt j and when the eye is in motion, though we are fenfible of its motion, yet, if we do not imagine that it moves fo fwiftly as it really does, we afcribe on¬ ly a part of the motion to the eye, and the reft of it we afcribe to the objeCt, though it be aCtually at reft. This laft, he fays, is what happens in the prefent cafe, when the eye turns round $ for though we are fenfible of the motion of the eye, yet we do not apprehend that it moves fo faft as it really does *, and therefore the bo¬ dies about appear to move the contrary way, as is agree¬ able to experience. But the great difficulty ftill remains, viz. Why, after the eye ceafes to move, objeCts ffiould, for fome time, ftill appear to continue in motion, though their pictures on the retina be really at reft, and do not at all change their place. This, he imagined, proceeds from a mif- take we are in with refpeCt to the eye, which, though it be abfolutely at reft, we neverthelefs conceive as mo¬ ving the contrary way to that in which it moved be¬ fore y from which miftake, with refpeCt to the motion of the eye, the objeCts at reft will appear to move the fame way which the eye is imagined to move; and, confequently, will feem to continue their motion for 194 fome time after the eye is at reft. Wells This is ingenious, but perhaps not juft. An ac* fur thls ptu; count of this matter, which feems to us more fatisfac- nomen0n, tory, '2 4*5 Apparent place, See. of objedls. *95 Upon what data we judge, vifi- ble objects to be in motion or at reft. OPT tory, has been lately given to the public by Dr Wells. “ Some of the older writers upon optics (fays this inge¬ nious philofopher) imagined the vifive fpirits to be con¬ tained in the head, as water is in a veiTc) ; which, there¬ fore, when once put in motion by the rotation of our bo¬ dies, mint continue in it for fome time after this has ceafed ; and to this real circular movement of the vifive fpirits, while the body is at reft, they attributed the ap¬ parent motions of objefts in giddinefs. Dechales faw the weaknefs of this hypothefis ; and conjectured, that the phenomenon might be owing to a real movement of the eyes ; but produced no fa£t in proof of his opinion. Dr Porterfield, on the contrary, fuppofed the difficulty of explaining it to confift in ffiowing, why objeCts at reft appear in motion to an eye which is alfo at reft. The folution he offered of this reprefentation of the phenomenon, is not only extremely ingenious, but is, I believe, the only probable one which can be given. It does not apply, however, to the faCt which truly exifts •, for I ffiall immediately (how, that the eye is not at reft, as he imagined. The latt author I know of who has touched upon this fubjecl is Dr Darwin. His words are, ‘ When any one turns round rapidl} on one foot till he becomes dizzy, and falls upon the ground, the fpeCtra of the ambient objeCts continue to prefent them- felves in rotation, or appear to librate, and he feems to behold them for fofne time in motion.’ I do not in¬ deed pretend to underftand his opinion fullyy but this much feems clear, that if fuch an apparent motion of the furrounding objeCts depends in any w'ay upon their fpeCtra, or the illufive reprefentations of thofe objeCts, occaftoned by their former impreffions upon the retinas, no fnnilar motion would be obferved, were we to (urn ourfelves round with our eyes (hut, and not to open them till we became giddy ; for in this cafe, as the furround¬ ing objeCts could not fend their pictures to the retinas, there would confequently be no fpeCtra to prefent them- felves afterward in rotation. But whoever will make the experiment, will find, that objeCts about him appear to be equally in motion, when he has become giddy by turning himfelf round, whether this has been done with his eyes open or (hut. I (hall now venture to propofe my own opinion upon this fubjeCt. “ If the eye be at reft, we judge an objeCt to be in motion when its picture falls in fucceeding times upon different parts of the retina ; and if the eye be in mo¬ tion, wre judge an objeCt to be at reft, as long as the change in the place of its picture upon the retina holds a certain correfpondenee with the change of the eye’s pofition. Let us now fuppofe the eye to be in motion, while, from fome diforder in the fyftem of fenfation, wre are either without thofe feelings which indicate the va¬ rious pofitions of the eye, or are not able to attend to them. It is evident, that in fuch a flate of things an objeCt at relt muff; appear to be in motion, fince it fends in fucceeding times its picture to different parts of the retina. And this feems to be what happens in giddi¬ nefs. I was firft led to think fo from obferving, that, during a flight fit of giddinefs I was accidentally feized with, a coloured foot, occafioned by looking fteadily at a luminous body, and upon which I happened at that moment to be making an experiment, was moved in a manner altogether independent of the pofitions I conceiv¬ ed my eyes to poffefs. To determine this point, I again produced the fpot, by looking fome time at the flame of 4 I C S. Part I. a candle : then turning rnyfelf round till I became gid- Apparent dy, I fuddenly difeontinued this motion, and directed Pj.iU'h &c- my eyes to the middle of a fheet of paper, fixed upon , ° ^ the wall of my chamber’. The fpot now appeared upon the paper, but only for a moment 5 for it immediately after feemed to move to one fide, and the paper to the other, notwithftanding I conceived the polition of my eyes to be in the mean while unchanged. To go on Curious ex. with the experiment, when the paper and fpot had pro- Per>ments ceeded to a certain diftance from each other, they fud- ^k^certa^ denly came together again j and this feparation and con¬ junction were alternately repeated a number of times, the limits of the feparation gradually becoming lefs, till at length the paper and fpot both appeared to be at reft, and the latter to be projected upon the middle of the former. I found alfo, upon repeating and varying the experiment a little, that w7hen I had turned myfelf from left to right, the paper moved from right to left, and the fpot confequently the contrary way •, but that when I had turned from right to left, the paper would then move from left to right. Thefe were the appearances obferved while I flood ereCt. When I inclined, how¬ ever, my head in fueh a manner as to bring the fide of my face parallel to the horizon, the fpot and paper would then move from each other, one upward and the other downward. But all thefe phenomena demonftrate, that there rvas areal motion in my eyes at the time 1 imagi¬ ned them to be at reft ; for the apparent fituation of the fpot, with refpeCt to the paper, could not poffibly have been altered, without a real change of the pofition of thofe organs. To have the fame thing proved in another way, I defired a perfon to turn quickly round, till he became very giddy j then to flop himfelf, and look ftedfaftly at me. He did fo, and I could plainly fee, that although he thought his eyes were fixed, they wrere in reality moving in their foekets, firft toward one fide and then toward the other.” ^ M. Le Cat well explains a remarkable deception, by A remark- which a perfon {hall imagine an objeCt to be on the op- a.We (’*eceP- polite fide of a board, when it is not fo, and alfo invert-t on ex‘ ed and magnified. It is illuftrated by fig. 6. in which Cat D reprefents the eye, and CB a large black board, Plate pierced with a fmall hole. E is a large white board, ccclxxxiv. placed beyond it, and ftrongly illuminated •, and , becaufe it fills a greater portion g F with light. The point K itfelf, and every other point in the fpace KL, muft ap¬ pear very luminous, fince they fend entire pencils of rays EKI, ELF, to the eye j and the viiible bright- nefs of every point from L towards M, mull decreafe gradually, as from K to N, that is, the fpaces KN, LM, will appear as dim fhadowy borders, or fringes, adja¬ cent to the edges of the opaque bodies. When the edge G is brought to touch the right line KF, the penumbras unite \ and as foon as it reaches NDF, the above phenomenon begins ; for it cannot pafs that right line without meeting fame line « D d, drawn from a point between N and K, and, by intercepting all the rays that fall upon the pupil, render it invifible. In advancing gradually to the line KDE, it will meet other lines 6 Df, c D g, &c. and therefore render the points b, c, &c. from N to K, fucceflively invifible ^ and therefore the edge of the fixed opaque body CD muft I'eem to fwell outwards, and cover the whole fpace NK ; while GH, by its motion, covers MK. When GH is placed at a greater diftance from the eye, CD continu¬ ing fixed, the fpace OP to be paffed over in order to in¬ tercept NK is lefs; and therefore, with an equal motion of GH, the apparent fwelling of CD muft be quicker ; which is found true by experience. If ML reprefent a luminous objeft, and REFQ^any plane expofed to its light, the fpace FQ will be entire¬ ly ftiaded from the rays, and the fpace FE will be oc¬ cupied by a penumbra, gradually darker, from E to F. Let now GH continue fixed, and CD move parallel to the plane EF; and as foon as it pafles the line LF, it is evident that the fhadow QF will feem to fwell out¬ wards ; and when CD reaches ME, fo as to cover with its fhadow the fpace RE, £)F, by its extenfion, will co¬ ver FE. T his is found to hold true likewife by experi¬ ment. Sect. X. On Abler at ion of Figure or Sphericity. 199 Theory of _ The great praftical ufe of the fcience of optics is to aberration, aid human fight; but it has been repeatedly obferved during the progrefs of thjs article, that in conftru&ing dioptrical inftruments for this purpofe, great difficulties Plate arife the aberration of light. It has been fhown ccclxxviii. how to determine the concourfe of any refradted ray 'it5- 5, <5, Ph’ with the ray RVCF’, which pafles through the centre C, and therefore falls perpendicularly on the 'I C S. 247 fpherical furface at the vertex V, and fuffers no refrac- lion. This is the conjugate focus to R for the two rays Wenation. IIP, RV, and for another ray flowing from R and falling on the furface at an equal diftance on the op¬ pofite fide to P. In fhort, it is the conjugate focus for all the rays flowing from R, and falling on the fphe¬ rical furface in the circumference of a circle deferibed by the revolution of the point P round the axis RVCF j that is, of all the rays which occupy the conical fur- face deferibed by the revolution of RP, and the re- fradled rays occupy the Conical furface produced by the revolution of PF’. But no other rays flowing from R are colledled at F’ j for it appeared in the demonftration of that propofition, that rays incident at a greater diftance from the axis RC were collefted at a point between C and F’ j and then the rays which are incident on the whole arch PC, or the fpherical furface generated by its revolution round RC, although they all crofs the axis RC, are diflfufed over a certain portion of it, by what has been called the aberration of figure. It is called alfo (but impro¬ perly) the aberration from the geometrical focus, by which is meant the focus of an infinitely {lender pencil of rays, of which the middle ray (or axis of the pencil) occupies the lens RC, and fuffers no refradfion. But there is no luch focus. But if we make 7//RV—«RC : «RV—VC : VF, the point F is called the geometrical focus, and is the remoteft limit from C of all the foci (equally geometrical) of rays flowing from R. The other limit is eafily determined by conftrudfing the pro¬ blem for the extreme point of the given arch. It is evident from the conftrudfion, that while the point of incidence P is near to V, the line CK increafes but very little, and therefore CF diminifties little, and the refradfed rays are but little diffufed from F; and therefore they are much denfer in its vicinity than any other point of the axis. It will foon be evident that they are incomparably denfer. It is on this account that the point F has been called the conjugate focus to R, and the geometrical focus, and the diffufion has been called aberration. A geometrical point R is thus repre- fented by a very fmall circle at F, and F has drawn the chief attention. And as, in the performance of optical inftruments, it is neceflary that this extended reprefen- tation of a mathematical point R be very fmall, that it may not fenfibly interfere with the reprefentations of the points adjacent to R, and thus caufe indiftindf vifion, a limit is thus fet to the extent of the refracting furface which muft be employed to produce this reprefentatien. But this evidently diminifties the quantity of light, and renders the vifion obfeure though diflinCt. Artifts have therefore endeavoured to execute refraCting furfaces of forms not fpherical, which colleCt accurately to one point the light ifluing from another, and the mathema¬ ticians have furnifhed them with forms having this pro¬ perty : but their attempts have been fruitlefs. Spheri¬ cal furfaccs are the only ones which can be executed with accuracy. All are done by grinding the refraCHng fubftance in a mould of proper materials. When this is fpherical, the two work tbemfelves, with moderate at¬ tention, into an exaCl fphere ; becaufe if any part is more prominent than another, it is ground away, and the whole gets of neceffity one curvature. And it is aftonifiiing to what degree of accuracy this is done. An error of the millionth part of an inch would totally de- ftroy 248 OPTICS. Part ] Of ftroy the figure of a mirror of an inch focal dillance. Aberration. ^ ag ^ ma]^e jt \ifelefs for the coarfeft inftrument. Therefore all attempts to make other figures are given up. Indeed other reafons make them worfe than fphe- rical, even when accurately executed. They would not collect to accurate focufes the rays of oblique pencils. It is evident from thefe obfervations, that the theory of aberrations is abfolutely neceffary for the fuccefsful conftruftion of optical inftruments j and it muft be ac¬ ceptable to the reader to have a fhort account of it in this place. Enough fliall be faid here to fhow the general nature and effedls of it in optical inftruments, and in feme of the more curious phenomena of nature. Under the article Telescope the fubjeft will be refum¬ ed, in fuch a manner as to enable the reader who pof- feffes a very moderate fnare of mathematical knowledge, not only to underftand how aberrations are increafed and diminilhed, but alfo how, by a proper employment of contrary aberrations, their hurtful effects may be almoji entirely removed in all important cafes. And the man¬ ner in which the fubiefl ftiall be treated in the prefent general Iketch, will have the advantage of pointing out at the fame time the maxims of conftruftion of the greateft part of optical inftruments, which generally produce their effetfts by means of pencils of rays which are either out of the axis altogether, or are oblique to it 5 cafes which are feldom confidered in elementary treatifes of optics. Plate Let PV it be a fpherical furface of a refra&ing fub- Ccclxxxiv. ftance (glafs for inftance), of which C is the centre, and %• 200 How to re¬ medy the evils of ab. •erration. let an indefinitely flender pencil of rays AP ap be inci¬ dent on it, in a dire£tion parallel to a ray CV pafling through the centre. It is required to determine the focusy*of this pencil. Let AP be refradled into PF. Draw Cl, CR the fines of incidence and refraftion, and CP the radius. Draw RB perpendicular to CP, and parallel to AP or CV. I fay, firft, f is the focus of the inde¬ finitely flender pencil, or, more accurately fpeaking, f is the remoteft limit from P of the concourfe of rays with PF’ refradled by points lying without the arch VP, or the neareft limit for rays incident between V and P. Draw the radius C p c’’, the line p f; and draw pg parallel to Pj^ and P 0 perpendicular to Pyi It is evident, that if f be the focus, c' pf is the angle of refradlion correfponding to the angle of incidence C, as C’P/ is the angle correfponding to A PC. Alfo VCp is the increment of the angle of incidence, and the angle c1 pg is equal to the fum of the angle C’P f and C’C c, and the angle ^ is equal to the angle pf¥. Therefore c’/jyhrC’Py-j-P, Cy7,-f-Pyp. There¬ fore PCp-j-PfP is the correfponding increment of the angle of refraftioA. Alfo, becaufe RP o=:CPp (being right angles) the angle p P o“RPC, and P 0 : Pp~ PR : PC. Therefore by a preceding Lemma in tins article, we have PCjo-LI3 f p : PC/>rrtan. ref. : tan. incid.rt: T, R : T, 13 and Yfp : PCp~T, R—T, I : T, I, : T, I; but F/p : FCp= — PR : Py,=:DR: DB (becaufe DP is parallel to By by conftrudHon)=ztan.CPR—-tan.CPI: tan.CPI. Now CPI is the angle of incidence $ and therefore CPR is the angle properly correfponding to it as an angle of re- Of fraction, and the pointy is properly determined. Aberrat'o Hence the following rule. As the difference of the tangents of incidence and refraftion is to the tangent of incidence, fo is the radius of the furface multiplied by the cofne of refraBion to the di/lance of the focus of an inf* nitely fender pencil of parallel incident rays. N. B. We here confider the cofine of refraction as a number. This was firft done by the celebrated Euler, and is one of the greateft improvements in mathematics which this century can boaft of. The fines, tangents, fecants, &.c. are confidered as fractional numbers, of which the radius is unity. Thus, CP X fin. 30°, is the 1 CP fame tiling with — CP, or And in like manner, CB, drawn perpendicular to the axis Xftn. 190 28' 16" 1 CB 32"', is the fame thing with - of CB. Alfo —a J ’ 3 cof. 60 is the fame thing with twice CB, &c. In this manner, BEzrBCxfin. BCE, and alfo BE =:CE X tan. BCE, and CB=CE X fee. BCE, &c. &c. This manner of confidering the lines which occur in geometrical conftruCtions is of immenfe ufe in all parts of mixed mathematics ; and nowhere more remarkably than in optics, the molt beautiful example of them. Of this an important inftance lhall now be given. Cor. 1. The diftance yG of this lateral focus from the axis CV (that is, from the line drawn through the centre parallel to the incident light) is proportional to the cube of the femi-aperture PH of the fpherical fur¬ face. For yG=BE. Now BE=CB xfm. BCE, =CB X fin. CPA •, and CB=RCxcof. RCB, =RC x fin. CPR, and RCrzCPxfin. CPR : Therefore BE=rPC Xfin.1 CPR X fm. PC A, —PCxfin.*refr. xfm. incid. but fin.* refr. =r ^-fin.* incid. Therefore, finally, BE, n 772* J or yG=PC X “7 X fin.3 incid,: But PC, fin. inerd. is evidently PH the femi-aperture ; therefore the propofi- tion is manifeft. Cor. 2. Now let this flender pencil of rays be inci¬ dent at the vertex V. The focus will now be a point F in the axis, determined by making CV : CFriw— n : m. Let the incident pencil gradually recede from the axis CF, ftill, however, keeping parallel to it. The focusy will always be found in a curve line DC’F, fo conltituted that the ordinate G will be as the cube of the line PH, perpendicular to the axis intercepted be¬ tween the axis and that point of the furface which is cut by a tangent to the curve in f All the refracted rays will be tangents to this curve, and the adjacent rays will crofs each other in thefe la¬ teral foci y,- and will therefore be incomparably more denfe along the curve than anywhere within its area. This is finely illuftrated by receiving on white paper the light of the fun refracted through a globe or cylift^ der of glafs filled with water. If the paper is held pa¬ rallel to the axis of the cylinder, and clofe to it, the il¬ luminated part will be bounded by two very bright pa¬ rallel lines, where it is cut by the curve ; and thefe lines will gradually approach each other as the paper is with¬ drawn from the veffel, till they coalefce into one very bright Theory. 'OPT Oi bright line at F, or near it. If tlie paper be held with Aberration. Jts encl touching the veffel, and its plane nearly perpen- ^ ’ dicular to the axis, the whole progrefs of the curve will be diftinitly feen. As fuch globes were ufed for burning glaffes, the point of greateft condeniation (which is very near but not exactly in F) was called the focus. W hen thefe curves were obferved by Mr Tchirnhaufs, he called them caufics; and thofe formed by refraftion he called dia- cuufics, to diftinguifh them from the cutacaujhcs form¬ ed by refledtion. It is fomewhat furprifing, that thefe curves have been fo little ftudied lince the time of Tchirnhaufs. The doc¬ trine of aberrations has indeed been confidered in a man¬ ner independent on their properties. But whoever con- fiders the progrefs of rays in the eye-piece of optical in- Itruments, will fee that the knowledge of the properties of diacaultic curves determines directly, and almoft ac¬ curately, the foci and images that are formed there. For, let the obje£t-glafs of a telefcope or microfcope be of any dimenlions, the pencils incident on the eye-glalfes are almoft all of this evanefcent bulk. Thefe advan¬ tages will be fliown in their proper places: and we pro¬ ceed at prefent to extend our knowledge of aberrations in general, firft confidering the aberrations of parallel incident rays. Abiding by the inftance reprefented by the figure, it is evident that the cauftic wrill touch the furface in a point will touch the furlace, and will crofs the axis in , the neareft limit of diffufion along the axis. If the furface is of fmaller extent, as PV, the cauftic begins at 7^ when the extreme refraCted ray Pf touches the cauftic, and croffes the axis in F’, and the oppofite branch of the cauftic in K. If there be drawn an ordi¬ nate KO k to the cauftic, it is evident that the whole light incident on the furface PVn pafles through the circle whofe diameter is K £, and that the circle is the tot fmalleft fpace which receives all the refrafted light. How light It is of great importance to confider the manner in ted over11' ^ie %^t is diftributed over the furface of this the fmalleft cjrc^e fmalleft diffufion : for this is the reprefenta- jcircle of tion of one point of the infinitely diftant radiant objeCt. ‘liffufion. Each point of a planet, for inftance, is reprefented by this little circle j and as the circles reprefenting the dif¬ ferent adjacent points muft interfere with each other, an indirtindtnefs muft arife fimilar to what is obferved when we view an object through a pair of fpeftacles which do not fit the eye. The indiftin&nefs muft be in propor¬ tion to the number of points whofe circles of diftufion interfere j that is, to the area of thefe circles, provided that the light is uniformly diffufed over them : but if it be very rare at the circumference, the impreflion made by the circles belonging to the adjacent points muft be lefs fenfible. Accordingly, Sir Ifaac Newton, fuppofing it incomparably rarer at the circumference than towards the centre, affirms that the indiftinftnefs of telefeopes, arifing from the fpherical figure of the obje ]SJ0VV fuppofe the ruler to revolve gra- - y—jts extremity moving acrofs the arch FAy* of the refra£Hng furface while the edge is applied to the caultic j the point of contact with the cauitic will fhift gradually down the branch DV of the cauftic, while its edge pafles acrofs the line c C \ and when the point of contact arrives at V, the extremity will be at Y on the refrafting furface, and the interfedtion of the edge will be at O. 3. Continuing the motion, the point of contadl Ihifts from V to Z, the extremity from Y to and the interfedlion from O to fo oc* that 00*=:-—, as will prefently appear. 4. After this, the point of contafl will fhift from Z to C, the extremity from O’ to X, half way from F to A, as will foon be fliown, and the interfedlion from 0.to C. 9. The point of contact will now drift from C down to I-, the extremity w ill pafs, from X to A, and the interfedlion will go back from C to O. 6. The ruler mud now be applied to the other branch of the caudic \ c %v d, and the point of contadl will afeend from I to c, the extremity will pafs from A to x, half way to f from A, and the interfedtion from O to c. 7. The point of contadl will afeend from C to 2;, the extremity paffes from x to 7’, and the interfedlion from * O c* C to y, O 7* being =: 8. While the contadl of the ruler and caudic drifts from % to v, the extremity drifts from y’ to y, and the interfeflion from 7 to O. 9. The contaft rifes from v to d, the extremity paffes from yto f, and the interfedlion from O to Cj and then the motion acrofs the refradling furface is completed, the point of contaft drifting down from D to I along the branch DVZCI, and then afeending along the other branch I c% v d, while the interfefrion paffes from c to C, back again from C to c, and then back again from c to C, where it ends, having thrice paffed through every 202 intermediate point of c C. Denfity of We may form a notion of the dendty of the light light. in any point H, by fuppodng the incident light of uni¬ form dendty at the refra£ling furface, and attending to the condipation of the rays in the circle of Imalleft diffudon. Their vicinity may be edimated both in the dire&ion of the radii OH, and in the direction of the circumference deferibed by its extremity H, during its revolution round the axis ; and the denfity mud be con¬ ceived as proportional to the number of originally equidi- flant rays, which are colle&ed into a fpot of given area. Thefe have been collefred from a correfponding fpot or area of the refrafring furface; and as the number of rays is the fame in both, the denfify at H will be to the denfity of the refrafring furface, as the area occupied of the refrafring furface, to the correfponding area at H. The vicinity of the rays in the diretlion of the radius depends on the proportion betuTeen PT and TH. For the ray adjacent to PTH may be fuppofed to crofs it at the point of contact T ; and therefore the uniform didance between them at the furface of that medium is to the didance between the fame rays at H as the didanee of T from the refrafting furface to its didance from H. Therefore the number of rays which occupy a tenth of an inch, for example, of the radius AP, is to the number which would occupy a tenth of an inch at H as TH to TP} and the radial denfity at P is to the 2 I C S. Parti. radial dendty at H, aim as TH to TP. Inthenext place, Of The circumferential dendty at P is to that at H as the ra- ^)erra ion, dius AP to the radius OH. For fuppodng the figure to v "l~J turn round its axis AI, the point P of the refrafring furface will deferibe a circumference whofe radius is AP, and H will deferibe a circumference whofe radius is OH; and the whole rays which pafs through the firft circumference pafs alfo through the lad, and therefore their circumferential dendties will be in the inverfe proportion of the fpaces into which they are collefted. Now the radius AP is to the radius OH as AL to OL •, and circumferences have the fame proportion with their radii. Therefore the circumferential den¬ fity at P is to that in H as AL to OL inverfely ; and it was found that the radial dendty was as AN to ON inverfely, being as TH to TP, which are very nearly in this ratio. Therefore the abfolute dendty (or number of rays collefred in a given fpace) at P will be to that at H, in the ratio compounded of thefe ratios; that is, in the ratio of ON X OL to AN X AL. But as NL bears but a very fmall ratio to AN or AL, AN X AL may be taken as equal to AO* without any feniible error. It never differs from it in telefcopes I ooth part, and is generally incomparably fmaller. Therefore the denfity at H may be confidered as proportional to ON X OL inverfely. And it will afterwards appear that NS is =: 3 oL. Therefore the denlity at H is in¬ verfely as ON xNS. Now deferibe a circle on the diameter OS, and draw NTcp catting the circumference N^rrON xNS, and the denfity at H is as Ni the hole afcend and defcend, when between its two contrary motions it feemed ftationary, I flopped the prifm ; in this fituation of the prifm, viewing through it the faid hole E, I ob¬ ferved the length of its refraCled image pt to be many times greater than its breadth 5 and that the moft re- fraCled part thereof appeared violet at p ; the leaft re- fraCIed, at L; and the middle parts indigo, blue, green, I i 2 » yellow. 252 OPT % 3- On the dif• yellow, ancf orange, in order. The fame thing happen- ferent re- e(j wjien j removed the prifm out of the fun’s light, and fToafn£jb^ty looked through it upon the hole ihining by the light of i°'- /gn ' . the clouds beyond it. And yet if the refractions of all the rays were' equal according to one certain proportion of the lines of incidence and refraftion, as is vulgarly fuppofed, the refracted image ought to have appeared round, by the mathematical demonftration above men¬ tioned. So then by thefe two experiments it appears, that in equal incidences there is a confiderable inequali¬ ty of refraCtions.” For the difcovery of this fundamental property of light, which has unfolded the whole myltery of colours, avc fee our author was not only beholden to the experi¬ ments themfelves, which many others had made before him, but alfo to his Ikiil in geometry j which was abfo- lutely neceffary to determine what the figure of the re- fraCted image ought to be upon the old principle of an equal refraCtion of all the rays : but having thus made the difcovery, he contrived the following experiment to prove it at fight. _ Plate “In the middle of two thin boards, DE d c, I ecclxxxiii. ma(je a round hole in each, at G and g, a third part of an inch in diameter j and in the window-fhut a much larger hole being made, at F, to let into my darkened chamber a large beam of the fun’s light, I placed a prifm, ABC, behind the Ihut in that beam, to. refraCt it towards the oppofite wall *, and clofe behind this prifm I fixed one of the boards DE, in fuch a manner that the middle of the refraCted light might pafs through the hole made in it at G, and the reft be intercepted by the board. Then at the diftance of about 12 feet from the firft board, I fixed the other board, d e, in fuch manner that the middle of the refra&ed light, which eame through the hole in the firft board, and fell upon the oppofite wall, might pafs through the hole g in this other board de, and the reft being intercepted by the board, might paint upon it the coloured fpeCtrum of the fun. And clofe behind this board I fixed another prifm a be, to refraCI the light which came through the hole g. Then I returned fpeedily to the firft prifm ABC, and by turning it florvly to and fro about its axis, I caufed the image which fell upon the fecond board d e, to move up and down upon that board, that all its parts might pafs fucceffively through the hole on that board, and fall upon the prifm behind it. And in the mean time I noted the places, M, N, on the oppofite Avail, to which that light after its refraftion in the fecond prifm did pafs ; and by the difference of the places at M and N, I found that the light, Avhich being moft refra&ed in the firft prifm ABC, did go to the blue end of the image, was again more refra&ed by the fecond prifm a b c, than the light Avhich went to the red end of that image. For when the lower part of the light Avhich fell upon the fecond board d e, Avas call through the hole g, it went to a lower place M on the Avail •, and when the higher part of that light was call through the fame hole g, it went to a higher place N on the wall j and when any intermediate part of the light Avas call through that hole, it went to fome place in the Avail be¬ tween M and N. The unchanged pofition of the holes in the boards made the incidence of the rays upon the fecond prifm to be the fame in all cafes. And yet in that common incidence fome of the rays were more re¬ fra&ed and others lei’s ; and thofe Avere more refra&ed I C S. Part I. in this prifm, which by a greater refra&ion in the firft On the dif. prifm were more turned out oi their Avay ; and, there- ^erent r«- fore, for their conftancy of being more refra&ed, are de- fervedly called more refrangible” t ^ ^ Sir ifaac IhoAvs alfo, by experiments made with con- 205 vex glafs, that lights, refle&ed from natural bodies, hefledted Avhich differ in colour, differ alfo in refrangibility j and^1 ^er- that they differ in the fame manner as the rays of the franaib^. fun do. “ The fun’s light confifts of rays differing in reflexibi¬ lity, and thofe rays are more reflexible than others Avhich are more refrangible. A prifm, ABC, whofe tAvoFig. 4. angles, at its bafe BC, Avere equal to one another and half right ones, and the third at A a right one, I pla¬ ced in a beam FM of the fun’s light, let into a dark chamber through a hole F one third part of an inch broad. And turning the prifm flowly about its axis un¬ til the light which Avent through one of its angles ACB, and Avas refra&ed by it to G and H, began to be re¬ fle&ed into the line MN by its bafe BC, at Avhich till then it Avent out of the glafs j I obferved that thofe rays, as MH, which had fuffered the greateft refra&ion, Avere fooner refle&ed than the reft. To make it evident that the rays which vanifhed at H Avere refle&ed into the beam MN, I made this beam pafs through another prifm VXY, and being refra&ed by it to fall afterwards upon a ftieet of white paper p t placed at fome diftance behind it, and there by that refra&ion to paint the ufual colours at p t. Then caufing the firft prifm to be turned about its axis according to the order of the letters ABC, I obferved, that Avhen thofe rays MH, which in this prifm had fuffered the greateft refra&ion, and appeared blue and violet, began to be totally refle&ed, the blue and violet light on the paper which Avas moft refra&ed in the fecond prifm received a fenfible increafe at p, above that of the red and yellow at t: and afterwards, when the reft of the light, which was green, yellow, and red, began to be totally refle&ed and vaniftied at * G, the light of thofe colours at /, on the paper p t, re¬ ceived as great an increafe as the violet and blue had received before. Which puts it paft difpute, that thofe rays became firft of all totally refle&ed at the bafe BC, which before at equal incidences Avith the reft upon the bafe BC had fuffered the greateft refra&ion. I do not here take any notice of any refra&ions made in the fides AC, AB, of the firft prifm, becaufe the light en¬ ters almoft perpendicularly at the firft fide, and goes out almoft perpendicularly at the fecond ; and therefore fuffers none, or fo little, that the angles of incidence at the bafe BC are not fenfibly altered by it j efpecially if the angles of the prifm at the bafe BC be each about 40 degrees. For the rays FM begin to be totally re¬ fle&ed when the angle CMF is about 50 degrees, and therefore they will then make a right angle of 90 de¬ grees Avith AC. “ It appears alfo from experiments, that the beam of light MN, refle&ed by the bafe of the prifm, being augmented firft by the more refrangible rays and after- Avards by the lefs refrangible, is compoftd of rays dif¬ ferently refrangible. “ The light whofe rays are all alike refrangible, I call fmple, homogeneous, and fmilar ; ai d that whofe rays are fome more refrangible than others, I call compound, heterogeneous, and diffimilar. The former light I call homogeneous, not becaufe I would afhrm it fo in all re* fpe&s 3 Theory. OPT On the dif- fpe£ts } but becaufe tbe rays wbicli agree in refrangibi- ferent re- lity agree at lealt in all their other properties which I ^ y confider in the follotving difcourfe. i “ 1 he colours of homogeneous lights I call j)rt/nan/f homogeneous, and Jimple; and thole of heterogeneous lights, heterogeneous and compound. lor thefe are always •ompound. comPound?d of homogeneous lights, as will appear in ^ ' the following difcourfe. “ I he homogeneous light and rays which appear red, or rather make objeas appear fo, I call rubrijic or red- making ; thofe which make objeas appear yellow, green, blue, and violet, I call yellow-making, blue-making, vio¬ let-making-y and fo of the reft. And if at any time I fpeak of light and rays as coloured or endowed with co¬ lours, I would be underftood to fpeak not philofophical- ly and properly, but grofsly, and according to fuch conceptions as vulgar people in feeing all thefe experi¬ ments would be apt to frame. For the rays, to fpeak properly, are not coloured. In them there is nothing elfe than a certain power and difpofition to ftir up a fenfation of this or that colour. For as found, in a bell or mufical ftring or other founding body, is nothing but a trembling motion, and in the air nothing but that motion propagated from the objeft, and in the fenforium it is a fenfe of that motion under the form of found $ fo colours in the objeft are nothing but a difpofition to re- fleft this or that fort of rays more copioufly than the reft : in rays they are nothing but their difpofitions to propagate this or that motion into the fenforium ; and in the fenforium they are fenfations of thofe motions un¬ der the forms of colours. See Chromatics. “ By the mathematical propofition above mentioned, it is certain that the rays which are equally refrangible heteroge-7 uPon a cIrcle anfwering to the fun’s apparent diik, neous rays w^ch will alfo be proved by experiment by and by. Now let AG reprefent the circle which all the moft re¬ frangible rays, propagated from the whole dific of the fun, will illuminate and paint upon the oppofite wall if were alone •, EL the circle, which all the leaft re- ccckxxiii. frangible rays would in like manner illuminate if they % 5- were alone j BH, Cl, DK, the circles which fo many intermediate forts would paint upon the wall, if they were fingly propagated from the fun in fucceflive order, the reft being intercepted \ and conceive that there are' other circles without number, which innumerable other intermediate forts of rays would fucceffively paint upon the wall, if the fun ftiould fucceflively emit every fort apart. And feeing the fun emits all thefe forts at once, they muft all together illuminate and paint innumerable equal circles ; of all which, being according to their degrees of refrangibility placed in order in a continual feries, that oblong fpe&rum PT is compofed, which was defcribed in the firft experiment. t “ Now if thefe circles, whilft their centres keep their diftances and pofitions, could be made lefs in diameter, their interfering one with another, and confequently the mixture of the heterogeneous rays, would be propor- tionably diminiftied. Let the circles AG, BH, Cl, &c. remain as before ; and let ag, b h, c i, &c. be fo many lefs circles lying in a like continual feries, be¬ tween two parallel right lines a e and g l, with the fame diftance between their centres, and illuminated with the fame forts of rays : that is, the circle a g with the fame fort by which the correfponding circle AG was illuminated j and the reft of the circles b k, c i} d k, e lf I c s. 25. refpe&ively with the fame forts of rays by which the On the dif- correfponding circles LH, Cl, DK, EL, were illumi- j61,611.1 re 207 Why the image of pafling through a prifm, is oblong. Plate nated In the figure P ±\ compofed of the great circles, three of thofe, AG, iiH, Cl, are fo expanded into each other, that three forts of rays, by which thofe circles are illuminated, together with innumerable other forts of intermediate rays, are mixed at (^R in the middle of the circle BH. And the like mixture happens through¬ out almoft the whole length of the figure PT. But in the figure p t, compofed of the lefs circles, the three lefs circles a g, b h, c i, which anfwer to thofe three greater, do not extend into one another j nor are there any ivhere mingled fo much as any two of the three forts of rays by which thofe circles are illuminated, and which in the figure PT are all of them intermingled at QR. So then, if we would diminifh the mixture of the rays, wre are to diminilh the diameters-of the circles. Now thefe would be diminifhed if the fun’s diameter, to which they anfwer, could be made lefs than it is, or (which comes to the fame purpofe) if without doors, at great 1 diftance from the prifm towards the fun fome opaque body were placed with a round hole in the middle of it to intercept all the fun’s light, except fo much as com¬ ing from the middle of his body could pafs through that hole to the prifm. For fo the circles AG, BH, and the reft, would not any longer anfwer to the whole difk •of the fun, but only to that part of it which could be feen from the prifm through that hole j that is, to the apparent magnitude of that hole viewed from the prifm. But that thefe circles may anfwer more diftinftly to that hole, a lens is to be placed by the prifm to call the image of the hole (that is, every one of the circles AG, BH, &c.) diftinctly upon the paper at PT ; after fuch a manner, as by a lens placed at a window the piflures of objefls abroad are caft diftinttly upon the paper within the room. If this be done, it will not be neceflary to place that hole very far off, no not beyond the window. And therefore, inftead of that hole, I ufed a hole in the window-flint as follows. “ In the fun’s light let into my darkened chamber through a fmall round hole in my window ftiut, at about 10 or 12 feet from the window, I placed a lens MN, pi„ ^ by which the image of the hole F might be diftinftly caft upon a flieet of white paper placed at I. Then im¬ mediately after the lens I placed a prifm ABC, by which the trajefted light might be refrafted either upwards or fidewife, and thereby the round image which the lens alone did caft upon the paper at I, might be drawrn out into a long one with parallel fides, as reprefented at p t. This oblong image I let fall upon another at about the fame diftance from the prifm as the image at I, moving the paper either towards the prifm or from it, until I found the juft diftance where the redlilinear fides of the images p t become moft diftinft. For in this cafe the circular images of the hole, which compofe that image, after the manner that the circles a g, b h, c i, &c. do the figure p t, were terminated moft diftinftly, and therefore extended into one another the leaft that they could, and by confequence the mixture of the heteroge¬ neous rays was now the leaft of all. The circles a g, b h, c i, &c. which compofe the image p t, are each equal to the circle at I ; and therefore, by diminiftiing the hole F, or by removing the lens farther from it, may be diminiftied at pleafure, whilft their centres keep the fame diftances from each other. Thus, by diminifiiing the. frargibility of Light. 2*54- O P T by Ample and homo¬ geneous light, cir¬ cular. On the dif-hbe breadth of the imagejo/, tlie-circles of heterogeneal ferent re- rayS tjiat comp0{'e it may be feparated from each other of Li'dit as much as you pleafe. Yet inftead of the circular hole C—..1 F, it is better to fubftitute a hole lhaped like a pa¬ rallelogram, with its length parallel to the length of the prifm. For if this hole be an inch or two long, and but a 10th or 20th part of an inch broad, or narrower, the light of the image p t will be as Ample as before, or Ampler; and the image being much broader, is therefore fitter to have experiments tried in its light than before. “ Homogeneal light is refracted regularly without any dilatation, fplitting, or fliattering of the rays ; and the confufed vifion of objects feen through refrafting bodies by heterogeneous light, arifes from the different refran- 208 gibility of feveral forts of rays. This will appear by the The^age experiments which will follow. In the middle of a bv fimul'e' black paper I made a round hole about a fifth or a fixth part of an inch in diameter. Upon this part I caufed the fpectrum of homogeneous light, deferibed in the for¬ mer article, fo to fall that fome part of the light might pais through the hole in the paper. This tranfmitted }>art of the light, I refra&ed with a prifm placed be- lind the paper: and letting the refracted light fall per¬ pendicularly upon a white paper, two or three feet di- ftant from the prifm, I found that the fpeftrum formed on the paper by this light was not oblong, as when it is made in the firft experiment, by refrafting the fun’s compound light, but was, fo far as I could judge by my eye, perfeftly circular, the length being nowhere greater than the breadth ; which (hows that this light is refra&ed regularly without any dilatation of the rays, and is an ocular demonftration of the mathematical pro- pofition mentioned above. “ In the homogeneous light I placed a paper circle of a quarter of an inch in diameter : and in the fun’s un- refraUed, heterogeneous, white light, I placed another paper circle of the fame bignefs; and going from thefe papers to the diftance of fome feet, I viewed both cir¬ cles through a prifm. The circle illuminated by the fun’s heterogeneous light appeared very oblong, as in the fecond experiment, the length being many times greater than the breadth. But the other circle, illuminated with homogeneous light appeared circular, and diftin£lly defined, as when it is viewed by the naked eye; which proves the whole propofition mentioned in the begin¬ ning of this article. “ In the homogeneous light I placed flies and fuch like minute objects, and viewing them through a prifm I faw their parts as diftinftly defined as if I had viewed them with the naked eye. The fame objedls placed in heterogene- the tun’s unrefrafted heterogeneous light, which was ©us light, white, I viewed alfo through a prifm, and faw them moft confufedly defined, fo that I could not diftinguiih their fmaller parts from one another. I placed alfo the letters of a fmali print one while in the homogeneous light, and then in the heterogeneous; and viewing them through a prifm, they appeared in the latter cafe fo confufed and indiitrnfl that I could not read them ; but in the former, they appeared fo dillindh that I could read readily, and thought I faw them as diftindl as when I viewed them with my’naked eye: in both cafes, I view¬ ed the fame objects through the fame prifm, at the fame •diftance from me, and in the fame fituation. There was no difference but in the lights by which the objedls 2*!p Vifion more di¬ ll incl in homogene ou than ir I C S. Parti. wrere illuminated, and which in one cafe was Ample, in On the dif the other compound ; and therefore the diftindt vifion ferent ,re- in the former cafe, and confufed iu the latter, could anfe from nothing elfe than from that difference in the ^ j lights. Which proves the whole propofition. “ In thefe three experiments, it is farther very re¬ markable, that the colour of homogeneous light was never changed by the refradlion. And as thefe colours were not changed by refradlions, fo neither were they by refledlions. For all white, gray, red, yellow, green, blue, violet bodies, as paper, allies, red lead, orpi- ment, indigo, bice, gold, filver, copper, grafs, blue flowers, violets, bubbles of water tinged with various colours, peacock feathers, the tindlure of lignum ne- phriticum, and fuch like, in red homogeneous light ap¬ peared totally red, in blue light totally blue, in green light totally green, and fo of other colours. In the homogeneous light of any colour they all appeared to¬ tally of that fame colour; with this only difference, that fome of them refledted that light more ftrongly, others more faintly. I never yet found any body which by refledling homogeneous light could fenfibly change its colour. “ From all which it is manifeft, that if the fun’s light confifted of but one fort of rays, there would be but one colour in the world, nor would it be poflible to produce any new1 colour by refledlions and refradtions ; and by confequence, that the variety of colours depends upon the compofition of light. “ The folar image p /, formed by the feparated rays in the 6th experiment, did in the progrefs from its end p, on which the moft refrangible rays fell, unto its end /, on which the leaft refrangible rays fell, appear tinged with this feries of colours; violet, indigo, blue, green, yellow, orange, red, together with all their intermedi¬ ate degrees in a continual fucceflion perpetually vary¬ ing ; fo that there appeared as many degrees of colours as there were forts of rays differing in refrangibility. And fince thefe colours could not be changed by re¬ fradlions nor by refledlions, it follows that all homoge¬ neal light has its proper colour anfwering to its degree of refrangibility. 2IQ “ Every homogeneous ray confidered apart is refradl- Every ho¬ ed, according to one and the fame rule ; fo that its mogeneous fine of incidence is to its fine of refradlion in a given ray 15 je‘ ratio: that is, every different coloured ray has a dif- ferent ratio belonging to it. This our author hasor,e an(i proved by experiment, and by other experiments has the fame determined by what numbers thofe given ratios are ex- rule- prefied. For inftance, if an heterogeneous white ray of the fun emerges out of glafs into air ; or, which is the fame thing, if rays of all colours be fuppofed to fuccecd pjate one another in the fame line AC, and AD their com-ccclx xiifi mon fine of incidence in glafs be divided into 50 equal fig* im¬ parts, then EF and GH, the fines of refradlion into air, of the leaft and moft refrangible rays, will be 7 and 78 fuch parts refpedlively. And fince every co¬ lour has feveral degrees, the fines of refradlion of all the degrees of red will have all intermediate degrees of magnitude from 77 to 77-g, of all the degrees of orange from 77^ to 77^-, of yellow from 774- to 774» of green from 77^ to 774 of blue from 774 to 77-f, of indigo from 77-} to 77-J, and-of violet from 77-J to 78.” PART OPTICS. Part II. Of the Rainbow. PART II. EXPLANATION OF OPTICAL PHENOMENA. 25J Of the Rainbow. Sf.CT. I. Of the Rainbow. The obfervations of the ancients, and the philofophers of the middle ages, concerning the rainbow, were fuch as could not have efcaped the notice of the meft illiterate hufbandmen ; and their various hypothefes deferve no KnowLdgc n°tice* ^ ^ a conliderable time, even after the dawn of of the na-8 true philofophy, before we find any difeovery of impor- tureofthe tance on this fubjeft, Maurolycus was the firft who rambow a pretended to have meafured the diameters of the two cover™ with much exa&nefs j and he found that of C0Ver}’ the inner bow to be 450, and that of the outer bow 56°; from which Defcartes takes occafion to obferve, how little we can depend upon the obfervations of thofe who were not acquainted with the caufe of the pheno¬ mena. Clichtovaeus, who died in 1543, had maintained, that the fecond bow is the image of the firft, which he thought was evident from the inverted order of the colours. Forr faid he, when we look into the water, all the images that we fee refle&ed by it are inverted with refpeft to the objefts themfelves •, the tops of the trees, for in- fiance, that ftand near the brink, appearing lower than the roots. As the rainbow was oppofite to the fun, it was natural to imagine, that its colours were produced by feme kind of refie&ion of the rays of light from the Approach ^roPs °f rain. No perfon feems to have thought of towards it aferibing thefe colours to refraftion, till one Fletcher made by of Breflaw, in a treatife publifhed in 1571, endeavoured Ere flaw" ^ t0 accoimt ^or them by means of a double refradlion and one reflexion. But he imagined that a ray of light, after entering a drop of rain, and fuftering a refraftion both at its entrance and exit, w^as afterwards reflefted from another drop, before it reaches the eye of the fpec- tator. He feems to have overlooked the refie&ion at the pofterior furface of the drop, or to have imagined that all the bendings of the light within the drop would not make a fufficient curvature to bring the rays of the fun to the eye of the fpeftator. That he Ihould think of two refraflions, was the neceffary confequence of his fuppofing that the ray entered the drop at all. This fuppofition, therefore, was all that he inftituted to ex¬ plain the phenomena. B. Porta fuppofed that the rain¬ bow is produced by the refraction of light in the Avhole 2i- body of rain or vapour, but not in the feparate drops. The difeo- ft to a man who had no pretenfions to philofophy, wry made that we are indebted for the true explanation. This was de Donfiidb J^nt0n^° ^ biftiop of Spalatro, whofe treatife bifhop of Pe Ra(his Vifus et Lucis, was publifhed by J. Bartolus Spalatro. 1611. He firft maintained, that the double refrac¬ tion of Fletcher, with an intervening reflection, was fufficient to produce the colours of the bow, and alfo to bring the rays that formed them to the eye of the fpec- tator, without any fubfequent reflection. He diftinctly deferibes the progrefs of a ray of light entering the up¬ per part of the drop, where it fuffers one refraction, and after being thereby thrown upon the back part of she inner furface, is thence reflected to the lower part of the drop j at which place undergoing a fecond refraction, it is thereby bent, lo as to come directly to the eye. To verify this hypothefis, De Dominis pro¬ ceeded in a very fenfible and philofophical manner. He procured a fmall globe of folid glafs, and viewing it when it was expofed to the rays of the fun, in the fame manner in which he had fuppofed that the drops of rain were fituated with refpect to them, he actually obferved the fame colours which he had feen in the true rainbow, and in the fame order. Thus the circumftances in which the colours of the rainbow were formed, and the progrefs of a ray of light through a drop of water, were clearly underftood j but philofophers were a long time at a lofs when they endea- voured to affign reafons for all the particular colours, and for the order of them. Indeed nothing but the doctrine of the different refrangibili'ty of the rays of light, could furniffi a complete folution of this difficulty. De Dominis fuppofed that the red rays were thofe which had traverfed the leaft fpace in the infide of a drop of water, and there¬ fore retained more of their native force, and confequently, ftriking the eye more brilkly, gave it a ftronger fenfa- tion •, that the green and blue colours were produced by thofe rays, the force of which had been, in fome meafure, obtunded in palling through a greater body of water ; and that all the intermediate colours were compofed (ac¬ cording to the hypothefis which generally prevailed at that time) of a mixture of thefe three primary ones. I hat the different colours were produced by fome differ¬ ence in the impulfe of light upon the eye, was an opi¬ nion which had been adopted by many perfons, who had ventured to depart from the authority of Ariftotle. Afterwards the fame De Dominis obferved, that all the rays of the fame colour muft leave the drop of wa¬ ter in a part fimilarly fituated with refpeft to the eye, in order that each of the colours may appear in a circle, the centre of which is a point of the heavens, in a line drawn from the fun through the eye of the fpeftator. The red rays, he obferved, muff iffue from the drop neareft to the bottom of it, in order that the circle of red may be the outermoft, and the moft elevated in the bow. Though De Dominis conceived fo juftly the manner in which the inner rainbow is formed, he was far from having as juft an idea of the caufe of the exterior bow. This he endeavoured to explain in the very fame manner as the interior, viz. by one reflection of the light within the drop, preceded and followed by a reflation ; fup¬ pofing only that the rays which formed the exterior bow were returned to the eye by a part of the drop lower than that which tranfmitted the red of the interior bow. He alfo fuppofed that the rays which formed one of the bows came from the upper limb of the fun, and thofe which formed the other from the lower limb, without confidering that the bows ought thus to have been con¬ tiguous ; or rather, that an indefinite number of bows would have had their colours all intermixed. When Sir liaac Newton difeovered the different re- frangibility of the rays of light, he immediately applied the difeovery to the phenomena of the rainbow, taking UT>i it. 256 OPT Of the up the fubje& where De Dominis and Defcartes were i ^ai,^ou'- obliged to leave their inveftigations imperfeft. 2I4 Let a be a drop of water, and S a pencil of light j The true which, on its leaving the drop reaches the eye of the caufeof the fpe&ator. This ray, at its entrance into the drop, be- colours of gjns to be decompofed into its proper colours } and up- b&tr1510" on ^eaving the drop, after one reflection and a fecond Plate refraction, it is farther decompofed into as many fmall ccclxxxiii. differently-coloured pencils as there are primitive co- %• s- lours in the light. Three of them Only are drawn in this figure, of which the blue is the moft, and the red the lealt, refrafted. The theory of the different refrangibility of light enables us to aflign a reafon for the fize of a bow of each particular colour. Newton, having found that the fines of refra£tion of the moft refrangible and leaft refrangible rays, in paflxng from rain water into air, are in the ratio of 185 to 182, when the fine of incidence is 138, com¬ puted the fize of the bow 5 and found, that if the fun was only a phyfical point, the breadth of the inner bow would be 20 ; and if to this 30' were added for the ap¬ parent diameter of the fun, the whole breadth would be 24°. But as the outer moft colours, efpecially the violet, are extremely faint, the breadth of the bow will not appear to exceed two degrees* He found, by the fame principles, that the breadth of the exterior bow, if it was everywhere equally vivid, would be 40 2o\ But in this cafe there is a greater dedudtion to be made, on account of the faintnefs of the light of the exterior bow ; fo that it will not appear to be more than 3 degrees broad. The principal phenomena of the rainbow are explain¬ ed on Sir Ifaac Newton’s principles in the following .propofitions. Prop. T. When the rays of the fun fall upon a drop of rain and enter into it, fome of them, after one re¬ flection and two refraCtions, may come to the eye of a fpeCtator who has his back towards the fun, and his face towards the drop. Explan a- If XY be a drop of rain, and if the fun ftiine upon it in tion of the any lines sf, s d, s a, &c. moft of the rays will enter phenomena jnto ^ 3rop . fome Df them only will be reflected from bow onthe furface » thofe rays which are thence reflected principles of do not come under our prefent confideration, becaufe Newton, they are never refraCted at all. The greateft part of the Tig. p. rays then enter the drop, and thofe palling on to the fe¬ cond furface, will moft of them be tranfmitted through the drop. At the fecond furface or hinder part of the drop, at p g, fome few rays will be reflected, whilft the reft are tranfmitted *, thofe rays proceed in fome fuch lines as 72 r, n q: and coming out of the drop in the lines rv, q t, may fall upon the eye of the fpeCtator, who is placed anywhere in thofe lines, with his face towards the drop, and confequently with his back towards the fun, which is fuppofed to fhine upon the drop in the lines sf,sd, x o, &c. Thefe rays are twice refraCted and once reflected ; they are refraCted when they pafs out of the air into the drop j they are reflected from the fecond furface, and are refraCted again when they pafs out of the drop into the air. Def. When rays of light reflected from a drop of ICS. Part U. rain come to the eye, thofe are called ejfe&ual which Of the are able to excite a fenfation. i Rainbow^ Prop. II. When rays of light come out of a drop of rain, they will not be effectual, unlefs they are paral¬ lel and contiguous. There are but few rays that can come to the eye at all : for fince the greateft part of thofe rays which enter the drop XY between X and a, pafs out of the drop >' through the hinder furface pg ; only few are thence re¬ flected, and come out through the nearer furface between a and Y. Now-, fuch rays as emerge, or come out of the drop, between a and Y, will be ineffectual, unlefs they are parallel to one another, as r and q t are j becaufe fuch rays as come out diverging from one an¬ other will be fo far afunder when they come to the eye, that all of them cannot enter the pupil ; and the very few that can enter it will not be fufficient to excite any fenfation. But even rays, which are parallel, as r q t, will not be effectual, unlefs there are feveral of them contiguous or very near to one another. The two rays rv and qt alone will not be perceived, though both of them enter the eye ; for fo very few rays are not fufficient to excite a fenfation. Prop. III. When rays of light come out of a drop of rain after one refle£tion, thofe will be effe£tual which are refle£ted from the fame point, and which entered the drop near to one another. Any rays, as x £ and c d. when they have paffed out plate of the air into a drop of water, will be refraCted towardsCCpLXXX1IJ’ the perpendiculars bl, dl; and as the ray sb falls far- ’ \ ther from the axis a v than the ray c d, s b will be more refraCted than c d; fo that thefe rays, though parallel to one another at their incidence, may defcribe the lines b e and d e after refraCtion, and be reflected from the fame point e. Now all rays, which are thus reflected from the fame point, when they have defcribed the lines e f eg, and after reflection emerge at f and g, will be fo refraCted, when they pafs out of the drop into the air, as to defcribe the parallel lines fh, g u If thefe rays were to return from e in the lines e b, e d, and were to emerge at b and d, they would be refraCted into the lines of their incidence b s, d c. But if thefe rays, in- ftead of being returned in the lines eb, e d, are reflected from the fame point e in the lines eg, ef the lines of reflection eg and e^/Tvill be inclined to one another and to the furface of the drop, juft as much as the lines e b and e d are. Firft, e b and e g make the fame angle with the furfaoe of the drop : for the angle hex, which eb makes with the furface of the drop, is the comple¬ ment of incidence, and the angle gev, which eg makes with the furface, is the complement of reflection } and thefe two are equal to one another. In the fame manner it might be ffiown, that e d and c f mabe equal angles with the furface of the drop. Secondly, The angle b c dz=f eg ; or the reflected rays eg, ef, and the inci¬ dent rays b e, d e, are equally inclined to each other. For the angle of incidence b el—g el, the angle of re¬ flection, and the angle of incidence d e I—f e l, the angle Part II. OPT Of the angle of reflection: confequently, the difference between ,^{ainl>ovv', the angles of incidence is equal to the difference between ^ the angles of refleftion, vr l> e l—d e /—g e 1—fe /, or be d—g ef. Since therefore either the lines eg, ef, or the lines c b, e d, are equally inclined both to one an¬ other and to the furface of the drop ; the rays will be refracted in the fame manner, whether they return in the lines e b, e d, or are reflected in the lines eg, ef. But if they return in the lines eh, ed, the refraction, when they emerge at b and d, would make them parallel. Therefore, if they are redeCted from one and the fame point e in the lines eg, ef, the refraCtion, when they emerge at ^ and/-, will likewife make them parallel. But though fuch rays as are reflected from the fame point in the hinder part of a drop of rain, are parallel to one another when they emerge, and fo have one condition that is requifite towards making them effec¬ tual, yet there is another condition neceffary ; for rays that are elfeCtual mult be contiguous as well as paral¬ lel. And though rays, which enter the drop in different places, may be parallel when they emerge, thole only will be contiguous which enter it nearly at the fame place. Fig. 9. Let XY be a drop of rain, ng the axis or diameter of the drop, and s a 2l ray of light that enters the drop at a. This ray s a, being perpendicular to both the fur- faces, will pafs through the drop in the line ug b without being refraCfed ; but any collateral rays, fuch as thofe that fall about j b, will be made to converge to the axis, and palling out at n will meet the axis at /i: Rays which fall farther from the axis than j- b, fueh as thofe which fall about s c, will likewife be made to converge ; but their focus will be nearer to the drop than h. Suppofe therefore 1 to be the focus of the rays that fall about s c, any ray s c, when it has deferibed the line co within the drop, and is tending to the focus i, will pafs out of the drop at the point 0. The rays that fall upon the drop about s d, will converge to a focus ftill nearer than i, as at k. Thefe rays therefore go out of the drop at p. The rays, that fall about s e, will con¬ verge to a focus nearer than h, as fuppofe at l; and the ray r e, when it has deferibed the line e 0 •within the drop, and is tending to /, will pafs out at the point 0. The rays that fall ftill more remote from the axis will converge to a focus ftill nearer. Thus the ray sf will after refraction converge to a focus at m, which is nearer than /; and having deferibed the line f n with¬ in the drop, it will pafs out to the point n. Now we may here obferve, that as any rays s b vs s c, fall farther above the axis r a, the points n, or 0, where they pafs out behind the drop, will be fartlier above g; or that, as the incident ray rifes from the axis s a, the arc g n 0 increafes, till we come to fome ray s d, which paffes out of the drop at p •, and this is the higheft point where any ray that falls upon the quadrant or quarter a x can pafs out : for any rays f e, or sf, that fall higher than f d, will not pafs out on any point above p, but at the points 0, or n, which arc below it. Confequently, though the arc g n 0 p increafes, whilft the diftance of the incident ray from the axis s a increafes, till we come to the ray s d; yet afterwards, the higher the ray falls above the axis s a, this arc pong will decreafe. We have hitherto fpoken of the points on the pof- terior part of the drop, where the rays pafs aut of it ; but this was for the fake of determining the points from which thofe ravs are refle&ed, which do not pafs out Vol. XV. Part'I. I CS. 257 behind the drop. For, in explaining the rainbow, we Of the have no further reafon to confider thofe rays which go Rainbow- through the drop ; fince they can never come to the eye v_ of ^ fpedator placed anywhere in the lines r v or q t with his face towards the drop. Now, as there are many rays which pafs out of the. drop between g and p, fo fome rays will be thence refle&ed: and conlequently the feveral points between ^ and p, which are the points where fome of the rays pafs out of the drop, are like¬ wife the points of refledlion for the reft which do not pafs out. Therefore in refpcift of thofe rays which are reflected, we may call^ p the arc of reflection 5 and may fay, that this arc of reflection increafes, as t,he diftance of the incident ray from the axis s a increafes, till we come to the ray s d; the arc of reflection is ^ n for the ray s b, it is ^ 0 for the ray s c, and g p for the ray s d. But after this, as the diftance of the incident ray from the axis s a increafes, the arc of reflection decreafes ; for og lefs than pg is the arc of reflection for the ray s e, and ng is the arc of reflection for the ray sf Hence it is obvious, that fome ray, which falls above s d, may be reflected from the fame point with fome other ray which falls below s d. Thus, for inftance, the ray s b will be reflected from the point n, and the rays sf will be reflected from the fame point 5 and confe¬ quently, when the reflected rays n r, n q, are refraCted as they pafs out of the drop at r and q, they will be pa¬ rallel. But fince the intermediate rays, which enter the drop between r/ and sb, are not reflected from the fame point n, thefe two rays alone will be parallel to one another when they come out of the drop, and the intermediate rays will not be parallel to them. And confequently thefe rays rv,qt, though they are parallel after they emerge at r and q, will not be contiguous, and for that reafon will not be effectual; the ray r is reflefted from p, which has been fhown to be the limit of the arc of reflection •, fuch rays as fall juft above s d, and juft below s d, will be reflected from nearly the fame point p, as appears from what has been already ftiown. Thefe rays therefore will be parallel, becaufe they are reflected from the lame point p; and they will likewife be contiguous, becaufe they all of them enter the drop at the fame place very near to d. Confe¬ quently, fuch rays as enter the drop at d, and are re¬ flected from p the limit of the arc of reflection, will be effectual fince, when they emerge at the part of the drop between a and y, they will be both parallel and contiguous. If it can be fhown that the rainbow is produced by the rays of the fun which are thus refitCted from drops of rain as they fall while the fun fliines upon them, this propofition may ferve to Ihow us, that this appearance is not produced by cr/iy rays that fall upon any part, and are refleCted from any part of thofe drops : finee this appearance cannot be produced by any rays but thofe which are effeChial 5 and effeClual rays mutt always en¬ ter each drop at one certain place in the anterior part of it, and muft likewife be reflected from one certain place in the pofterior furface. Prop. IV. . When rays that are effe£tual emerge from a drop of rain after one vefle£tion and two refrac¬ tions, thofe which are moft refrangible will, K k at 25« OPT Of the at their emciTion, make a lefs angle with the ^Rainbow., incident rays than thofe which are leaft re- ^ frangible 5, and by this means the rays of dif¬ ferent colours will be feparated from one ano¬ ther. ccci xxxin Letand ^ i be elfeaual violet rays emerging from %. ia. the drop at fg; and /?/, g p, effeaual red rays emer¬ ging from the fame drop at the fame place. Now, though all the violet rays are parallel to one another, becaufe they are fuppofed effettual, and though all the red rays are likewife parallel to one another for the fame reafon } yet the violet rays will not be parallel to the red rays. Thefe rays, as they have different degrees of refrangibility, will diverge from one another *, any vio¬ let ray g i, which emerges at g, will diverge from any red ray g p, which emerges at the fame place. Now, both the violet ray g i, and the red ray g p, as they pafs out of the drop of water into the air, will be refra6ted from the perpendicular / 0. But the violet ray is more refrangible than the red one } and for that reafon g z, or the refracted violet ray, will make a greater angle -with the perpendicular than g p the refraded red ray *, or the angle ig 0 will be greater than the angle p_g 0. Suppofe the incident ray j £ to be continued in The di- red ion s k, and the violet ray tg t© be continued back¬ ward in the diredion tk, till it meets the incident ray at £. Suppofe likewife the red raypg to be continued backwards in the fame manner, till it meets the incident ray at w. The angle iks is that which the violet ray, or moft re¬ frangible ray at its emerfion, makes with the incident ray ; and the angle pw s is that which the red ray, or leafl refrangible ray at its emerfion, makes with the in¬ cident ray. The angle t k s is lefs than the angle p w s. For, in the triangle, g w k, gws, or p w s, is the exter¬ nal angle at the bafe, and g k w or t k s is one of the in¬ ternal oppofite angles. (Euc. B. I. Prop. xvi.). What has been fhown to be true of the rays g i and gp might be fhoivn in the fame manner of the rays fh and fti, or of any other rays that emerge refpedively parallel to g 1 and g p. But all the effedual violet rays are parallel to g i, and all the effedual red rays are parallel to g p. Therefore the effedual violet rays at their emerfion make a lefs angle with the incident ones than the effec¬ tual red ones. For the fame reafon, in all the other forts of rays, thofe which are moft refrangible, at their emerfion from a drop of rain after one refledion, will make a lefs angle with the incident rays, than thofe do which are lefs refrangible. Otherwife: When the rays g i and g p emerge at the fame point g, as they both come out of water into air, and confequently are refraded from the perpen¬ dicular, iriftead of going ftraight forwards in the line e g continued, they will both be turned round upon the point g from the perpendicular g 0. Now it is eafy to conceive, that either of thefe lines might be turned in this manner upon the point g as upon a centre, till they became parallel to s b the incident ray. But if either of thefe lines or rays were refraded fo much from 0 as to become parallel to j b, the ray thus re¬ fraded, would, after emerfion, make no angle with J- becaufe it would be parallel to it. Confequently that ray which is moft turned round upon the point g, or that ray which is moft refrangible, will after emer¬ fion be neareft parallel to the incident ray, or will make I C S. Part It. the leaft angle with it. The fame may be proved of Of the all other rays emerging parallel to g 1 and g p re • , Itiunbow. fpedively, or of all effedual rays •, thofe which are moft 'r"'J refrangible will after emerfion make a lefs angle with the incident rays, than thofe do which are leaft refran¬ gible. But fince the effedual rays of different colours make different angles with jT at their emerfion, they will be feparated from one another: fo that if the eye were placed in the beam fgh i, it would receive only rays of one colour from the drop x agv; and if it were placed in the beam fg n p, it would receive only rays of feme other colour. The angle r wp, which the leaft refrangible or red rays make with the incident ones when they emerge fo as to be effedual, is found by calculation to be 420 2*. And the angle s k /, which the moft refrangible rays make with the incident ones when they emerge fo as to be effedual, is found to be 40° 17'. The rays which have the intermediate degrees of refrangibility, make with the incident ones intermediate angles between 420 2', and 40° 17'. Prop. V. If a line is fuppofed to be drawn from the centre of the fun through the eye of the fpe&ator, the angle which any effeddual ray, after two refrac¬ tions and one refledlion, makes with the inci¬ dent ray, will be equal to the angle which it makes with that line. Plate Let the eye of the fpedator be at i, and let <7 / be ccclxxxiii the line fuppofed to be drawn from the centre of the fun fig-I0- through the eye of the fpedator •, the angle g it, which any effedual ray makes with this line, will be equal to the angle ik s, which the fame ray makes with the in¬ cident ray s b or s k. If j- £ is a ray coming from the centre of the fun, then fince ^ / is fuppofed to be drawn from the fame, point, thefe two lines, upon account of the remotenefs of the point from whence they are drawn, may be looked upon as parallel to one another. But the right line k i crofling thefe two parallel lines will make the alternate angles equal. (Euc. B. I. Prop, xxix.). Therefore k it er g i t~s li. Prop. VI. When the fun fhines upon the drops of rain as they are falling, the rays that come from thofe drops to the eye of a fpe&ator, after one re- fledlion and two refractions, produce the pri¬ mary rainbow. If the fun (bines upon the rain as it falls, there are rajn. commonly feen two bows, as AFB, CHD j or if the feen cloud and rain does not reach over that whole fide of at once, the Iky where the bows appear, then only a part of one ^g'l1, or of both bows is feen in that place where the rain falls. Of thefe two bows, the innermoft AFB is the more vivid of the two, and this is called the primary bow. The outer part TFY of the primary bow is red, the inner part VEX is violet $ the intermediate parts, reckoning from the red to the violet, are orange, yel¬ low, green, blue, and indigo. Suppofe the fpedator’s eye to be at O, and let LOP be an imaginary line drawn Part II, OPT Of tbt? drawn from the centre of the fun through the eye of the Rainbow, fpeftator: if a beam of light S coming from the fun L..—„ fail upon any drop F j and the rays that emerge at F in the line -FO, fo as to be effectual, make an angle FOP of 42° l' with the line LP j then thefe effettua\ rays make an angle of 420 t! with the incident rays, >oy the preceding propofition, and confequently thefe. rays Will be red, fo that the drop F will appear red* All the other rays, which emerge at F, and would be ef¬ fectual if they fell Upon the eye, are refracted more than the red ones, and confcquently will paf, above the eye. If a beam of light S fall upon the, drop E, and the rajs that emerge at Ein the line F,0, fo as to be effeChial, make an angle of 40° 17' with the line LP ; ■then thefe- effeClual rays make like wife an angle of 40° 17' with the incident rays, and the drop E will appear of a violet colour. All the other rays, which emerge at E, and would be effeClual if they came to the eye, are refraCted Id’s than the violet ones, and therefore pafs below the eye. The intermediate drops between F and E will for the fame reafons be of the intermediate colours. 1 Thus we have ihown why a fet of drops from F to E, as they are falling, fhould appear of the feven pri¬ mary colours. It is not neceffary that the feveral drops, which produce thefe colours, fhould all of them fall at 'exaCily the fame diftance from the eye. The angle FOP, for example, is the fame whether the" diftance of the drop from the eye is OF, or whether it is in any other part of the line OF fomething nearer to the eye. And whilft the angle FOP is the fame, the angle made by the emerging and incident rays, and confequently the colour of the drop, will be the fame. This is equal¬ ly true of any other drop. So that though in the figure the drops F and E are reprefented as falling perpendicu¬ larly one under the other, yet this is not neeeffary in or¬ der to produce the bow. Kut the coloured line FE, which we have already accounted for, is only the breadth of the bow. It ftill remains bo be fliewn, why not only the drop F fhould appear red, but why all the other drops from A to B in the arc ATFYB ftiould appear of the fame colour. Now it is evident, that wherever a drop of rain is placed, if the angle which the effeClual rays make with the line LP is equal to the angle FOP, that is, if the angle which the effeClual rays make with the incident rays is 420 2', any of thofe drops will be red, for the fame reafon that the drop F is of this colour. If FOP were to turn round upon the line OP, fo that one end of this line ihould always be at the eye, and the other be at P oppofite to the fun ; fuch a motion of this figure would be like that of a pair of compaffes turning round upon one of the legs OP with the open¬ ing FOP. In this revolution the drop F would de- fcribe a circle, P would be the centre, and ATFYB would be an arc in this circle. Now lince, in this mo¬ tion of the line and drop OF, the angle made by FO with OP, that is, the angle FOP, continues the fame; if the fun were to fliine upon this drop as it revolves, the effeClual rays ivould make the fame angle with the incident rays, in whatever part of the arc ATFYB the drop was to be. Therefore, whether the drop be at A, or at T, or at Y, or at B, or wherever elfe it is in this whole arc, it would appear red, as it does at F. The drops of rain, as they fall, are not indeed turned I c s. - r-i/und in this manner ; but then, as great numbers of them are falling at once in right lines from the cloud, whilft one drop is at F, there will be others at Y, at 1, at B, at A, and in every other part of the arc A1 h\ B : and all thefe drops will be red for the fame reafon that the drop F would have been red, if it had been in the fame place. Therefore, when the fun ftiines upon the rain as it falls, there will be a red arc ATFYB oppofite to the fun. In the fame manner, becaufe the drop E is violet, we might prove that any other drop, which, whilft it is falling, is in any part of the are AVEXB, will be violet; and confequentlv, at the fame time that the red arc ATFYB appears, there will like- wife be a violet arc AVEXB below or within it. FE is the diftance between thefe two coloured arcs; and from what has been laid, it follows, that the interme¬ diate fpace between thefe two arcs will be filled up with arcs of the intermediate colours, orange, yellow, blue, green, and indigo. All thefe coloured arcs to¬ gether make up the primary rainbow. Prop. VII. The primary rainbow is never a greater arc than a femicircle. 2 5 9 Of the Rainbow. Since the line LOP is drawn from the fun through piate the eye of the fpeClator, and fince P is the centre of the ccclxxxih. rainbow ; it follows, that the centre of the rainbow is 9- always oppofite to the fun. The angle FOP is an angle 2I7 of 420 2', as was obferved, or F the higheft part of the Why the bow is 4 20 2' from P the centre of it.' If the fun is arc of the more than 42° 2' high, P the centre of the rainbow, which is oppofite to the fun, will be more than 420 2'never^' * below the horizon ; and confequently F the top of the greater bow, which is only 420 2' from P, will be below the'thai) a lemi- horizon; that is, when the fun is more than 420 2' high,circle* no primary rainbow will be feen. If the altitude of the fun be fomething Ids than 420 2r, then P will be fomething lefs than 42° 2r below the horizon ; and' confequently F, which is only 4 2° 2' from P, will be juft above the horizon ; that is, a fmall part of the bow at this height of the fun will appear clofe to the ground oppofite to the fun. If the lun be 20° high, then P will be 20° below the horizon ; and F the top of the bow, being 42° 2! from P, will be 22° 2! above the horizon ; therefore, at this height of the fun, the bow will be an arc of a circle whofe centre is below the horizon ; and confequently that arc of the circle which is above the horizon, or the bow, will be lefs than a femicircle. If the fun be in the horizon, then P, the centre of the bow, will be in the oppofite part of the horizon ; F, the top of the bow, will be 420 2! above the horizon ; and the bow itfelf, becaufe the horizon paffes through the centre of it, will be a femicircle. More than a femicircle can never appear ; becaufe if the bow were more than a femicircle, P the centre of it muft be above the horizon ; but P is always oppofite to the fun, therefore P cannot be above the horizon, un- lefs the fun is below it ; and when the fun is fet, or is below the horizon, it cannot fliine upon the drops of rain as they fall; and confequently, when the lun is below the horizon, no bow at all can be feen. Prop. VIII. When the rays of the fun fall upon a drop df rain, ' fome of them, after turn reflections and two re- K k 2 fractions, OPT fra£tions, may come to the eye of a fpe&ator, who has his back towards the fun and his face towards the drop. If HGW is a drop of rain, and parallel rays coming from the fun, as a “y, y w, fall upon the lower part of it, they will be refracted towards the perpendiculars v/, iu /, as they enter into it, and will defcribe fome fuch lines as v h, w i. At h and i great part of thefe rays will pafs out of the drop • but fome of them will be re¬ flected from thence in the lines hf, ig. At f and g again, great part of the rays that were reflected thither will pafs out of the drop. But thefe rays will not come to the eye of a fpeClator at o. Here, however, all the rays will not pafs out 5 but fome will be reflected from y'and^1, in fome fuch lines as f d, g h; and thefe, v'hen they emerge out of the drop of water into the air at b and d, will be refraCted from the perpendiculars, and, defcribing the lines d t, b 0, may come to the eye df the fpeCtator who has his back towards the fun and his face towards the drop. Prop. IX. Thofe rays, which are parallel to one another af¬ ter they have been oilce refracted and once re¬ flected in a drop of rain, will be effectual when they emerge after two refractions and two re¬ flections. No rays can be effectual, unlefs they arc contiguous and parallel. It appears from what was faid, that when rays come out of a drop of rain contiguous to one ano¬ ther, either after one or after two reflections, they mult enter the drop nearly at the fame place. And if fuch rays as are contiguous are alfo parallel after the firlt re¬ flection, they will emerge parallel, and therefore will be effectual. Let ss v and y iv be contiguous rays which come from the fun, and are parallel when they fall upon the lower part of the drop •, fuppofe thefe rays to be re¬ fraCted at v and w, and to be reflected at b and /; if they are parallel, as bf,g i, after this firft reflection, then, after they are reflected a fecond time from f and g, and refraCted a fecond time as they emerge at d and Z>, they will go out of the drop in the parallel lines dt and b 0, and will therefore be effectual. ■ The rays % v, y w, are refraCted towards the perpen¬ diculars v /, zv /, when they enter the drop, and will be made to converge. As thefe rays are very oblique, their focus will not be far from the furface vw. If this focus be at £, the rays, after they have paffed the focus, will diverge from thence in the directions b h, h i; and if k i is the principal focal diftance of the concave reflecting furface h 1, the reflected rays hf, ig, will be parallel. Thefe rays ef ig, are reflected again from the concave furface f g, and wull meet in a focus at e, fo that g e will be the principal focal diflance of this reflecting furface f g. And becaufe h i and f g are parts of the fame Iphere, the principal focal diflances g e and ki will be equal. When the rays have paffed the focus upon the circumference of the horizon acegy: and if the ■wall be continued to an immenfe diftance, its ex-, treme parts YZ will appear in the horizon at y z, where it is cut by a line O y parallel to the wall. For, fuppofing a ray YO, the angle YO y will become in- fcnlibly fmall. Imagine this infinite plane OAY y, with the wall upon it, to be turned about the horizontal line O like the lid of a box, till it becomes perpendicu¬ lar to the other half of the horizontal plane LM y, and the wall parallel to it, like a vaft ceiling overhead ; and then the wall xvill appear like the concave figure of the clouds overhead. But though the wall in the horizon appear in the figure of a femicircle, yet the ceiling will not, but much flatter. Becaufe the hori¬ zontal plane ivas a vifible furface, which fuggefted the idea of the fame diffances quite round the eye : but in the vertical plane extended between the eye and the ceiling, there is nothing that affedfs the fenfe with an idea of its parts but the common line O y ; confequently the apparent diftances of the higher parts of the ceiling will be gradually diminillied in afeending from that line. Now when the Iky is overcaft with clouds of equal gravities, they will all float in the air at equal heights above the earth, and confequently will compofe a fur¬ face refembling a large ceiling, as fiat as the vifible furface of the earth. Its concavity therefore is only apparent : and when the heights of the clouds are un¬ equal, fince their real fhapes and magnitudes are all unknown, the eye can felclom diftinguilh the unequal diftances of thofe clouds that appear in the fame di- reeftions, unlefs when they are very near us, or are driven by contrary currents of the air. So that the vifible ftiape of the whole furface remains alike in both cafes. And when the fky is either partly overcaft or partly free from clouds, it is matter of fadf that we re¬ tain much the fame idea of its concavity as when it was -\^q1y2tjie which is the only judge of an apparent figure, to be aconcavjty lefs portion of a fpherical furface than a hemifphere. of the fky Dr Smith fays, that the centre of the concavity isaPPears^s much below the eye : and by taking a medium among ^ftn,ar^e* feveral obfervations, he found the apparent diftance of * 1 its parts at the horizon to be generally between three and four times greater than the apparent diftance of its parts overhead. For let the arch ABCD repre-Tig. 10. fent the apparent concavity of the fky, O the place of the eye, OA and OC the horizontal and vertical ap¬ parent diftances, whole proportion is required. Firft obferve when the fun or the moon, or any cloud or flar, is in fuch a fituation at B, that the apparent arches BA, EC, extended on each fide of this object towards the horizon and zenith, feem equal to the eye ; then taking the altitude of the obje£f B with a quadrant, or a ends ftaflf, or finding it by aftronomy from the given time of obfervation, the angle AOB is known. Drawing therefore the line OB in the pofition thus determined, and taking in it any point B, in the ver¬ tical line CO produced downwards, find the centre E gf a circle ABC, whofe arches BA, BC, intercepted between B and the legs of the right angle AOC, fhall be equal to each other; then will this arch ABCD re- prefent Part II. O P T Pl»e colourprefent the apparent figure of the Iky. For by the eye yf the Sky. we eftimate the diftance between any two obje&s in the heavens by the quantity of fky that appears to lie be¬ tween them ; as upon each we eftimate it by the quan¬ tity of ground that lies between them. The centre E may be found geometrically by conftru&ing a cubic equation, or as quickly and fufficiently exadt by trying whether the chords BA, BC, of the arch ABC drawn by conjedture are equal, and by altering its radius BE till they are fo. Now in making feveral obfervations upon the fun, and fome others upon the moon and liars, they feemed to our author to bifedt the vertical arch ABC at B, when their apparent altitudes or the angle AOB was about 23 degrees j which gives the propor¬ tion of OC to OA as 3 to 10 or as 1 to 3^ nearly. When the altitude of the fun was 30°, the upper arch feemed always lefs than the under one; and, in our au¬ thor’s opinion, always greater when the fun was about 18 or 20 degrees high. Sect. IV. Of the Blue Colour of the Shj, and of Blue- and Green Shadows. Opinions of The opinions of ancient writers, concerning the colour the ancients of the Iky merit no notice. The firlt who gave any ra,- the^colour t^<)na* explanation was Fromondus. He fuppofed that the efthefky. bluenefs of the Iky proceeded from a mixture of the white light of the fun with the black fpace beyond the atmofphere, where there is neither refradHon nor reflec¬ tion. This opinion very generally prevailed, and was maintained by Otto Guerick and ab his contemporaries, who afferted, that white and black may be mixed in fuch a manner as to make a blue. M. Bouguer had rs- courfe to the vapours diffufed through the atmofphere, to account for the refledtion of the blue rays rather than any other. He feems, however, to fuppofe, that it arifes from the, con dilution of the air itfelf, from which the fainter-coloured rays are incapable of making their wray through any confiderable tradl of it. Hence he is of opinion, that the colour of the air is properly blue; to which opinion Dr Smith feems alfo to have inclined.. To this blue, colour of the fky is owing the appearance of blue and green fliadows in the morning and even- Grecn flia- —Thefe were firfl: obferved by M. Buffon in 1742, dowsobfer-when he noticed that the fhadows of trees which fell Buffon M’ UP0n a wb*te 'vab were green. He was at that time Handing upon an eminence, and the fun was fetting in the cleft of a mountain, fo that he appeared confiderably lower than the horizon. The iky was clear, excepting in the weft, which, though free from clouds, was light¬ ly (haded with vapour?, of a yellow colour, inclining to red. Then the fun itfelf was exceedingly red, and wras apparently at leaft four times as large as- he appears to be at mid-day. In thefe circumftances he faw very di- ftindily the fliadows of the trees, which were 30 or 40 feet from the white wall, coloured with a light green inclining to blue. The fliadow of an arbour, which was three feet from the wall, was exadllv drawn upon it, and looked as if it had been newly painted with ver- digrife. This appearance lafted near five minutes ; after which it grew fainter, and vaniflied at the fame saj time with the light of the fun. Blue ilia- The next morning at funriie, he went to obferve tedby him 0t^Cr upon another white wall; but inT-ad im of finding them green as before, he obferved that they I C S. 263. were of the colour of lively indigo. The iky was fe-Blue colour rene, except a flight covering of yellowifti vapours in ^ t'ie Skyy the eaft ; and the fun rofe behind a hill, fo that it was ’ elevated above his horizon. In thefe circumftances, the blue ihadows were only vifible three minutes ; after which they appeared black, and in the evening of the fame day he obferved the green ihadows exadtly as be¬ fore. On another day at funfet he obferved that the ihadows were not green, but of a beautiful iky-blue. He alfo obferved that the iky was in a great mea^ fure free from vapours at that time, and that the fun fet behind a rock, fo that it difappeared before it came to his horizon. Afterwards, he often obferved the ihadows both at funrife and funfet; but always per¬ ceived them to be blue, though with a great variety of (hades. 325 The firft perfon who attempted to explain this phe-Explana- nomenon was the Abbe Mazeas. He obferved that1^011 thefs when an opaque body was illuminated by the moon an Plvparch, indeed, attributes this appearance to the totalis e611 °f the fixed ftars reflected to us by the moon 5 but dipfed. " this is too weak to produce the effedl. The true caufe of it is the fcattered beams of the fun bent into the earth’s ftiadow by refractions through the atmofphere in the following manner. Plate Let the body of the fun be reprefented by the circle ccclxxxv. a b, and that of the earth by c d; and let the lines ace fig- 1. and b de touch them both, and meet in e beyond the earth ; then the angular fpace c e d will reprefent the conical figure of the earth’s ftiadow, which would be totally dark, were none of them bent into it by the re- fra&ion of the atmofphere. The rays a h and b z, which touch its oppofite fides, will proceed unrcfracled. Their difference * is Twice, horizontal refradlion — txu— 15—40 *Eucl 1 — nu x~ 67—30 Prop, xxxiu = / « zz — 83—10 \ Ibid, — tmu 62—JO Their fum f is Moon’s greateft horrz. parallax Therefore (by a preceding prop.) we have tm : / z/=r (ang. tnu \ ang. tmu—Shf—IC,, : 62'—io,|,~)4 : 3 in round numbers ; which was to be proved. It is eafy to colled! from the moon’s greateft horizontal parallax of 62'—10", that her leaf! diftance tm is about 55^ fe- midiameters of the earth ; and therefore the greateft: length t n of the dark fliadow, being three quarters of tm, is about femidiameters. The difference of the laft-mentioned angles / n z/, tjnu is mun—21', that is, about two-thirds of 31'— 40", the angle which the whole diameter of the furr fubtends at u. Whence it follows, that the middle point m of the moon centrally eclipfed, is illuminated by rays which come from two-thirds of every diameter of the fun’s difk, and pafs by one fide of the earth ; and alfo by rays that coins from the oppofite two-thirds of every r Part II. Ulumina- every one of the faid diameters, and pafs by the other tion of the picje 0f ^]ie garth. This will appear by conceiving the theEarth ra3r n ^ o r n to ^e inflexible, and its middle point a to ■ t ' Aide upon the earth, while the part r n is approaching to touch the point m; for then the oppofite part y a will trace over two thirds of the fun’s diameter. The true proportion of the angles n u m, a a s, could not be preferved in the fcheme, by reafon of the fun’s immenfe diflance and magnitude with refpedl to the earth, fig. 3. Having drawn the line at a, it may be obferved, that all the incident rays, as «y, oik, flowing from any one point of the fun to the circumference of the earth, will be colle&ed to a focus oc, whofe diftance t a is lefs than t m in the ratio of 62 to 67 nearly •, and thus an image of the fun will be formed at c* /3, whofe rays will diverge upon the moon. For the angle /« « is the difference of the angles x u u, u ot, t found above ; and t a, : t ni— ang. 1111 u : ang. t ot, a — 62'—\o" : 67—30". The rays that flow next above a q and a k, by paf- fmg through a rarer part of the atmofphere, Avill be United at a point in the axis at a farther from the earth than the laft focus « 5 and the fame may be faid of the rays that pafs next above thefe, and fo on 5 whereby an infinite feries of images of the fun will be formed, whofe diameters and degrees of brightnefs will increafe with their diftances from the earth. Hence it is manifeft why the moon eclipfed in her pe¬ rigee appears always duller and darker than in her apo- 267 gee. The reafon why her colour is always of the cop- IHumina- per kind, between a dull red and orange, feems to be t}l^ this : The blue colour of a clear iky (hows that the the'1 Earth, blue rays are more copioufly refledled from pure air than u-—y—j thofe of any other colour 5 confequently they are lefs 237 copioufly tranfmitted through it among the reft that^hyrhe come from the fun, and fo much the lefs as the traft °f ^u's duiier air through which they pafs is the longer. Hence the when eelip- • common colour of the fun and moon is whiteft in the fed in her meridian, and grows gradually more inclined to diluted Perig^e ^ yellow, orange, and red, as they defcend lovirer, that is,than in iet as the rays are tranfmitted through a longer traft of ‘1 J air ■, which tra£l being Hill lengthened in pafling to the moon and back again, caufes a ftill greater lofs of the blue rays in proportion to the reft ; and fo the refulting colour of the tranfmitted rays muft lie between a dark orange and red, according to Sir Ifaac Newton’s rule for finding the refult of a mixture of colours. The circular edge of the ftiadow in a partial eclipfe appears red 5 be- caufe the red-making rays are the leaft refradted of all others, and confequently are left alone in the conical furface of the ftiadow, all the reft being refradled in¬ to it. Dr Herfchel, who believes that the moon is phofpho- refcent, and that fhe fliines by her native light, when to¬ tally eclipfed by the fun, has endeavoured to ftiew, by calculation, that the light refracted by the atmofphere cannot in fome cafes fall upon the moon. O. P T I C S. PART III. ON THE CONSTRUCTION OF OPTICAL INSTRUMENTS. Chap. I. Defcription cf Optical Injlrutnents. OF the mechanifm of optical inftruments, particular accounts are given in this work under their refpective names. Thefe it would be improper to repeat 5 but as it belongs to the feience of optics to explain, by the laws of refradlion and refledtion* the feveral phenomena which thofe Inftruments exhibit, We muft here enume¬ rate the inftruments themfelves, omitting entirely, or Hating very briefly, fuch fadts as are given at large in other places. Sect. I. The Multiplying Glafs. The multiplying glafs is made by grinding down Plate convex fide h zT of a plano-Convex glafs AB, into ccclxxxvi feveral flat furfaces, as h h, b ld, dh. An objedt C will fig. 1. not appear magnified when feen through this glafs by 238 the eye at H 5 but it will appear multiplied into as ma- Multiply- hy different objedts as the glafs contains plane furfaces. in6 For, fince rays will flow from the objedt C to all parts of the glafs, and eacli plane furface will refradt thefe rays to the eye, the fame objedt will appear to the eye in the diredtion of the rays which enter it through each furface. Thus, a ray g iH, falling perpendicularly on the middle furface, will go through the glafs to the eye without fuffering any refradtion 5 and will therefore Ihow the objedt in its true place at C : whilft a ray a b flowing from the fame objedt, and falling obliquely on the plane furface b h, will be refradted in the diredtion b e, by pafling through the glafs 5 and, upon leaving it, will go on to the eye in the diredtion e H ; which will make the fame objedt C appear alfo at E, in the direc¬ tion of the ray H fp;g an objeft-glafs c d, and an eye-glafs e/. The fmall object a b is placed at a little greater diftance from the glafs c d than its principal focus j fo that the pencils of rays floAving from the different points of the oSje£t, and pafling through the glafs, may be made to com^erge, and unite in as many points betAveen^g and h, Avhere the image of the objeft Avill be formed ; Avhich image is viewed by the eye through the eye-glafs For the eye-glafs being fo placed, that the image g h may be in its focus, and the eye much about the fame diftance on 'the other fide, the rays of each pencil Avill be parallel after going out of the eye-glafs, as at e andyj till they come to the eye at k, Avhere they Avill begin to con¬ verge by the refractive power of the humours 5 and af¬ ter Part HI. ■ OPT Optical In- ter having croiTed each other in the pupil, they will be ftruments. coiie£l:ed into points on the retina, and form upon it the ' v large inverted image AB. Ufeoffeve- ^7 this combination of lenfes, the aberration of the ral lenfes in light from the figure of the glafs, which in a globule of a compound [he hind above mentioned is very confiderable, is in oiicrofcope. fome meaful-e' corrected. This appeared fo fenfibly to be the cafe, even to former opticians, that they very foon began to make the addition of another lens. For, fays Mr Martin, it is not only evident from the theory of this aberration, that the image of any point is ren¬ dered lefs confufed by refraction through two lenfes than by an equal refraCtion through one 5 but it alfo follows, from the fame principle, that the fame point has its image ftill lefs confufed when formed by rays refraCted through three lenfes than by an equal refraftion through two 5 and therefore a third lens added to the other will contribute to make the image more diflinft, and confe- quently the inftrumcnt more complete. At the fame time the field of view is amplified, and the ufe of the microfcope rendered more agreeable, by the addition of the other lens. Thus alfo we may allow a fomewhat larger aperture to the objeft lens, and thus increafe the brightnefs of obje&s, and greatly heighten the pleafure of viewing them. For the fame reafon, Mr Martin has propofed a four-glafs microfcope, which anfwers the purpofes of magnifying and of diftindt vilion ft ill more perfectly. Fig. p. The magnifying power ©f double microfcopes is ea- fily underftood, thus: The glafs L next the objeCt PQ. is very fmall, and very much convex, and confequently its focal diftance LF is very fhort •, the diftance LQ of the fmall objeCt PO is but a little greater than LF : Greater it muft be, that the rays flowing from the ob¬ jeCt may converge after pafling through the giafs, and crofling one another, form an image of thq objeCt; and it muft: be but a little greater, that the image p q may be at a great diftance from the glafs, and confe¬ quently may be much larger than the objeCt itfelf. This picture p q being viewed through a convex glafs AE, whofe focal diftance is q E, appears diftihCt as in a telefcope. Now the objeCt appears magnified for two reafons ; firft, becaufe, if we viewed its picture p q with the naked eye, it would appear as much greater than the objeCt, at the fame diftance, as it really is greater than the objeCt, or as much as L y is greater than LQ^ and fecondly, becaufe this picture appears magnified through the eye-glafs as much as the leatl dif¬ tance at which it can be feen diftinCtly with the naked eye, is greater than q E, the focal diftance of the eye- glafs. If this latter ratio be five to one, and the former ratio of L y to LQ be 20 to 1 ; then, upon both ac¬ counts, the objeft will appear 5 times 20, or 100 times greater than to the naked eye. The feClion of a compound microfcope with three Fig. io. lenfes is reprefentcd in fig. to. By the middle one GK the pencil of rays coming from the objeCl-glafs are re- fraCted fo as to tend to a focus at () ; but being inter¬ cepted by the proper eye-glafs DF, they are- brought together at I, which is nearer to that iens than its pro¬ per focus at L *, fo that the angle 13 IF, under which the object now appears, is larger than DLF, under which it would have appeared without this additional glafs \ and confequently the objeCt is more magnified in the fame proportion. Dr Hooke informs us, that, in ICS. 271 moft of his obfervations, he made ufe of a double mi- Optical In- crofcope with this broad middle glafs when he wanted i^nimcnts-| to fee much of an objeCt at one view, and taking it out v when he would examine the fmall parts of an objeCl more accurately ; for the fewer refraClions there are, the more bright and clear the objefl appears. The following rule for finding the magnifying power of compound microfcopes with three lenfes, has been given by Dr Brewfter in his Appendix to Fergufon’s Lectures, vol. ii. p. 468. “ Divide the difference between Magnifying the diftance of the two firft lenfes, or thofe next the ob- power of jedl, and the focal diftance of the fecond or amplifying comP, the rays of each pen¬ cil, after pafling through that glafs, will become paral¬ lel among themfelves ; but the pencils themfelves will converge confiderably with refpeft to one another, even fo as to crofs at c, very little farther from the glafs g h than its focus ; becaufe, when they entered the glafs,. their axes were almoft parallel, as coming through the obje£t-glafs at the point to whofe diftance the breadth of the eye-glafs in a long telefcope bears very fmall pro¬ portion. So that the place of the eye will be nearly at the focal diftance of the eye-glafs, and the rays of each refpeftive pencil being parallel among themfelves, and their axes crofling each other in a larger angle than they would do if the objeft were to be feen by the na¬ ked eye, vifion will be diftindt, and the objedl will ap¬ pear magriified. Its magni- The magnifying power in this telefcope is as the iyingpower, focal length of the objedl-glafs to the focal length of the eye-glafs. In order to prove this, we may confider the angle Ai B as that under which the objedt would be feen by the naked eye 5 for in confidering the diftance of the objedt, the length of the telefcope may be omitted, as bearing no proportion to it. Now the angle under which the objedt is feen by means of the telefcope is g e h, which is to the other A/§B, or its equal gk as the diftance from the centre of the objedt-glafs to that of the eye-glafs. The angle, therefore, which an ob- jedt fubtends to an eye aflifted by a telefcope of this kind, is to that under which it fubtends to the naked I C S. Part III. eye, as the focal length of the objedt-glafs to the focal Optical In¬ length of the eye-glafs. ftruments. It is evident from the figure, that the vifible area, v~'J or fpace which can be feen at one view, when we look through this telefcope, depends on the breadth of the eye-glafs, and not of the objedt-glafs ; for if the eye- glafs be too fmall to receive the rays g m, p h, the ex¬ tremities of the objedt could not have been feen at all: a larger breadth of the objedt-glafs conduces only to the rendering each point of the image more luminous, by receiving a larger pencil of rays from each point of the objedt. 2^t It is in this telefcope as in the compound microfcope, Objedls where we fee not the objedt itfelf, but only its imaged11 thro’ CED : now that image being inverted with refpedt to‘L !J1''ertecl' the objedt, becaufe the axis of the pencils that flow from the objedt crofs each other at k, objedts feen through a telefcope of this kind neceflarily appear in¬ verted. This is a circumftance not at all regarded by aftro- nomers: but for viewing objedts upon the earth, it is convenient that the inftrument Ihould reprefent them in their natural pofture ; to which ufe the telefcope with CCCLmvm three eye-glaffes, as reprefented fig. 13. is peculiarly fig. ^ adapted. AB is the objedt fending out the feveral pencils Acd, Be*/, &.c. which pafling through the objedt- glafs cd, are colledted into their refpedtive foci in CD, where they form an inverted image. From this they Common proceed to the firft eye-glafs ef, whofe focus being atrej™(^;in£ /, the rays of each pencil are rendered parallel among themfelves, and their axes, which were nearly paralleljeds ered. before, are made to converge and crofs each other : the fecond eye-glafs g Ji, being fo placed that its focus fhall fall upon m, renders the axes of the pencils which diverge from thence parallel, and caufes the rays of each, which were parallel among themfelves, to meet again at its focus EF on the other fide, where they form a fecond image inverted with refpedt to the for¬ mer, but eredt with refpedt to the objedt. Now this image being feen by the eye at a b through the eye- glafs ik, affords a diredt reprefentation of the objedt, and under the fame angle that the firft image CD w'ould have appeared, had the eye been placed at /, fuppofing the eye-glaffes to be of equal convexity j and therefore the objedt is feen equally magnified in this as in the former telefcope, that is, as the focal diftance of the objedt glafs to that of any one of the eye-glaffes, and appears eredt. 253 2. The Galilean Telefcope with the concave eye-glafs Galilean is conftrudted as follows. Opiate" I AB is an objedt fending forth the pencils of rays cccixxxviii. g h i, kltn, &c. which, after pafling through the ob- fig. 1, jedt-glafs c d, tend towards e Y. f (where we fliall fup- pofe the focus of it to be), in order to form an inverted image there as before j but in their way to it are made to pafs through the concave glafs n 0, fo placed that its focus may fall upon E, and confequently the rays of the feveral pencils which were converging towards thofe refpedlive focal points e, Y,f, will be rendered parallel, but the axes of thofe pencils crofling each other at F, and diverging from thence, will be rendered more di¬ verging, as reprefented in the figure. Now thefe rays entering the pupil of an eye, will form a large and di- flindl image a b upon the retina, which will be inverted with Part IIT. OPT Optical In- with refpeft to the objeft, becaufe the axis of the pen- ftruncnt". cj2s crofs in F. The objetl of courfe will be feen ereft, l*—"“v an(l the angle under which it will appear will be equal to that which the lines a¥,b F, produced back through the eye-glafs, form at F. It is evident, that the lefs the pupil of the eye is, the lefs is the vilible area feen through a telefcope of this kind ; for a lefs pupil would exclude fuch pencils as proceed from the extremities of the objedf AB, as is evident from the figure. This inconvenience renders this telefcope unfit for many ufes ; and is only to be re¬ medied by the telefcope with the convex eye-glaffes, where the rays which form the extreme parts of the image are brought together in order to enter the pupil of the eye, as explained above. It is apparent alfo, that the nearer the eye is placed to the eye-glafs of this telefcope, the larger is the area feen through it *, for, being placed clofe to the glafs, as in the figure, it admits rays that come from A and B, the extremities of the objedl, which it could not if s54 it was placed farther off. Magnify- ' The degree of magnifying in this telefcope is in the ing power. fame proportion with that in the other, viz. as the fo¬ cal diltance of the obje£t-glafs is to the focal diflance of the eye-glafs. For there is no other difference but this, viz. that as the extreme pencils in that telefcope were made to con- ^'ate .. verge and form the angle g e h or ink (fig. 13.), thefe ccclxxxvu. are now mac}e to diverge and form the angle a F b xclxxxviii (%• 1 •) ’ which angles, if the concave glafs in one has L * an equal refraftive power with the convex one in the other, will be equal, and therefore each kind will exhi¬ bit the object magnified in the fame degree. There is a deleft in all thefe kinds of telefcopes, not to be remedied in a fingle lens by any means what¬ ever, which was thought only to arife from the fphe- rical aberration of the objeA-glafs. But it was dif- covered by Sir Ifaac Newton, that the imperfection of this fort of telefcope, fo far as it arifes from the fpherical form of the glafies, bears little proportion to that which is owing to the different refrangibility of light. This diverfity in the refra&ion of rays is about a 28th part of the whole ; fo that the objeCt-glafs of a telefcope cannot coiled the rays which flow from any one point in the objeft into lefs fpace than a circle whofe diame¬ ter is about the 56th part of the breadth of the glafs. To (how this, let AB reprefent a convex lens, and r ?Iate.. let CDF be a pencil of rays flowing from the point D ; cccxxxvm. ^ ^ ^ tjie p0int at which the leaft refrangible rays are colleCted to a focus ; and I, that where the moft refrangible concur. Then, if IH be the 28th part of EH, IK will be a proportionable part of EC (the tri¬ angles HIK and HEC being fimilar) : confequently LK will be the 28th part of FC. But MN will be the leaft fpace into which the rays will be colleded, as ap¬ pears by their progrefs reprefented in the figure. Now MN is but about half of KL *, and therefore it is about the 56th part of the breadth of that part of the glafs through which the rays pafs ; which was to be ftiown. Since therefore each point of the objeCl will be re¬ prefented in fo large a fpace, and the centres of thofe fpaces will be contiguous, becaufe the points in the objeCt the rays flow from are fo j it is evident, that the image of an objeCt made by fuch a glafs mult be a 1 C 3. . _ 275 moft confufed reprefentation, though it does not appear Optical In¬ fo when viewed through an eye-glafs that magnifies in j-1’ p'f ‘A a moderate degree conlequently the degree of magni¬ fying in the eye-glafs muft not be too great with re- fpeCi to that of the objeCt-glafs, left the confulion be¬ come fenfible. Notwithllanding this imperfeCtion, a dioptrical te¬ lefcope may be made to magnify in any given degree, provided it be of fufficient length ; for the greater the focal diftance of the objeCf-glafs is, the lefs may be the proportion which the focal diftance of the eye-glafs may bear to that of the objeCt-glafs, without render- 255 ing the image obfcure. Thus, an objeCt-glafs, whofe Refladting focal diftance is about four feet, will admit of an eye- teict'x'' h5’ glafs whofe focal diftance {hall be little more than an inch, and confequently will magnify almoll 48 times *, to their but an objeCl-glafs of 40 feet focus will admit of an length, eye-glafs of only four inches focus, and will therefore magnify l ?o times; and an objeCt-glafs of 100 feet focus will admit of an eye-glafs of little more than fix inches focus, and will therefore magnify almoft 200 times* The reafon of this difproportion in their feveral de¬ grees of magnifying may be explained thus : Since the diameter of the fpaces, into which rays flowing from the feveral points of an objeCt are collected, are as the breadth of the objeCt-glafs, it is evident that the degree of confufednefs in the image is as the breadth of that glafs ; for the degree of confufednefs will only be as the diameters or breadths of thofe fpaces, and not as the fpaces themfelves. Now the focal length of the eye- glafs, that is, its power of magnifying, muft be as that degree ; for, if it exceeds it, it will render the confufed¬ nefs fenfible ; and therefore it muft be as the breadth or diameter of the objeCl-glafs. The diameter of the ob- jeft-glafs, which is as the fquare root of its aperture or magnitude, muft be as the fquare root of the power of magnifying in the telefcope ; for unlefs the aper¬ ture itfelf be as the power of magnifying, the image will want light: the fquare root of the power of mag¬ nifying will be as the fquare root of the focal diftance of the objeCl-glafs ; and therefore the focal diftanee of the eye-glafs muft be only as the fquare root of that of the objeCl-glafs. So that in making ufe of an objeCl-glafs of a longer focus, fuppofe, than one that is given, you are not obliged to apply an eye glafs of a proportionably longer focus than what would fyit the given objeCl-glafs, but fuch a one only whofe fo¬ cal diftance (hall be to the focal diftance of that wrhich will fuit the given objeCl-glafs, as the fquare root of the focal length of the objeCl glafs you make ufe of, is to the fquare root of the focal length of the given one. And this is the reafon that longer telefcopes are capable of magnifying in a greater degree than (horter ones, without rendering the objeCl confufed or coloured. Upon thefe principles the following new table, taken from the Appendix to Fergufon’s LeClures, vol. ii. p. 471. fecond edition, has been computed. It is founded on a telefcope of Huygens, mentioned in his AJtrofcopia Compendiaria, which had an objeCl-glafs 34 feet in fo¬ cal length, and which bore an eye-glafs of 24- inches fo¬ cal diflance, and therefore magnified 163 times. The tabF for refraCling telefcopes, which has been given by preceding optical writers, was copied from Smith’s Op- M m 2 tics? ftri.ments. 276 OPT Optical In-tics, as the produ£Hon of the celebrated Huygens, while it was calculated only by the editors of his Diop¬ trics, from a telefcope made by that celebrated optician •, which, however, feems to have been inferior to that which is the foundation of the following table. The table is fuited to Rhinland meafure 5 but the fecond and third columns may be converted into Englifh meafure by dividing them by ,7, the focal diftances of the obje£t- glaffes being fuppofed Englilb feet. A NEW Table of the apertures, focal lengths, and magnifying power of ref railing telefcopes. Focal length of the object-glafs Feet. 3 4 5 6 7 8 9 10 *3 15 20 25 3° 35 40 45 50 55 60 70 80 90 100 200 300 400 500 Sine or aper¬ ture of the eve-t;l ;fs. f h. Dec. Focal diftance of the eye-glafs. Inch. Dec. Magnifying power Times O.65 I-°3 1.3° I,45 1.61 1.79 1.96 2.14 2.20 2.32 2.63 2.81 3-31 3- 73 4.01 4- 34 4.64 4.92 c.20 5- 48 5-71 6.16 6.58 7.02 7-39 10.41 12.89 14.72 16.52 0.50 0.62 o-75 0.87 1.00 1.07 1.21 1.30 1.38 1.58 а. 70 1- 95 2.15 2.40 2.58 2.76 2- 93 3.08 3.22 3- 36 3-64 3- 90 4.12 4- 35 б. 17 7-52 8.71 9-71 28 39 48 55 60 67 73 77 83 87 99 106 123 i39 150 163 174 184 195 205 214 231 246 262 276 389 479 55i 618 Sect. VI. On Achromatic Telefcopes. 256 Their im- The inconveniency of very long telefcopes is fo great, perfect ons that different attempts have been made to remove it. byTvikfd O'f thefe, the moft fuccefsful have been by Dollond and and Blair. Blair; and the general principles upon which thefe emi¬ nent opticians proceeded have been mentioned in the hifto- rieal part of (his article, and in the preceding feftion. A fuller account of Dr Blair’s difeoverv will be feen in the Tran factions of the Royal Society of Edinburgh ; and of Dollond’s, it may be fufficient to obferve. in addition to what has been already faid, that the objeft-glaffes of his telefcopes are compofed of three diftinftlenfes, two convex and one concave ; of which the concave one is placed in 3* the middle, as is reprefented in fig. 3. where a and c Ihow I C s. Part III. the two convex lenfes, and b b the concave one, which Optical in. is by the Britifh artifts placed in the middle. The two ftruments. convex ones are made of London crown glafs, and the ^ 1 -1 middle one of white flint glafs; and they are all ground to fpheres of different radii, according to the relraftive' powers of the different kinds of glafs and the intended focal diftance of the objecl-glafs of the telefcope. Ac¬ cording to Bofcovich, the focal diftance of the parallel rays for the concave lens is one-half, and for the convex glafs one-third ol the combined focus. When put to¬ gether, they refradt the rays in the following manner. Let ab, a b, be two red rays of the fun’s light falling . parallel on the firft convex lens c. Suppofing there was 5' no other lens prefent but that one, they would be con¬ verged into the lines be, be, and at laft meet in the fo¬ cus q. Let the lines g h, g h, reprefent two violet rays falling on the furface of the lens. Thefe are alfo re- fradled, and will meet in a focus ; but as they have a greater degree of refrangibility than the red rays, they muff of confequence converge more by the fame power of refradtion in the glafs, and meet fooner in a focus, fuppofe at r.—Let now the concave lens d d be placed in fuch a manner as to intercept all the rays before they come to their focus. Were this lens made of the fame materials, and ground to the fame radius with the con¬ vex one, it would have the fame power to caufe the rays diverge that the former had to make them converge. In this cafe, the red rays would become parallel, and move on in the line 00,00: But the concave lens, being made of flint glafs, and upon a (hotter radius, has a greater refradlive power, and therefore they diverge a little af¬ ter they come out of it; and if no third lens was inter- pofed, they would proceed diverging in the lines opt, opt; but, by the interpofition of the third lens ov 0, they are again made to converge, and meet in a focus fomewhat more diftant than the former, as at x. By the concave lens the violet rays are alfo refrafted, and made to diverge ; but having a greater degree of refran¬ gibility, the fame power of refra&ion makes them di¬ verge fomewhat more than the red ones ; and thus, if no third lens was interpofed, they would proceed in fuch lines as //« «, ///2 n. Now as the differently coloured rays fall upon the third lens with different degrees of divergence, it is plain, that the fame power of refra&ion in that lens will operate upon them in fuch a manner as to bring them all together to a focus very nearly at the fame point. The red rays, it is true, require the great- eft power of refra&ion to bring them to a focus ; but they fall upon the lens with the leaft degree of diver¬ gence. The violet rays, though they require the leaft power of refraction, yet have the greateft degree of di¬ vergence ; and thus all meet together in the point x, or nearly fo. But, though we have hitherto fupuofed the refraction of 'he concave lens to be greater than that of the con¬ vex ones, it is eafy to fee how the errors occafioned by ccci^viii the firft lens may be corrected by it, though it (hould fig. ^ have even a lefs power of refradtion than the convex one. Thus, let a b, a b, be two rays of red light falling upon the convex lens c, and refraCted into the focus q ; let alfo g h, g h, be two violet rays converged into a fo¬ cus at r ; it is not neceffary, in order to their conver¬ gence into a common focus at x, that the concave lens Ihould make them diverge; it is fufficient if the glafs has Part III. OPT Optical In- has a power of dxfperfing the violet rays fomewhat more ■>trunieni5'. than the red ones; and many kinds have this power of difperfing fome kinds of rays, without a very great power of refraaion. It is better, however, to have the objed-glafs compofed of three lenfes ; became there is then another correaion of the aberration bv means of the third lensj and it might be impoflible to find two lenfes, the errors of which would exadly corred each other. It is alfo eafy to fee, that the effed may be the fame whether the concave glafs is a portion of the fame fphere with the others or notj the effed depending upon a combination of certain circumltances, of which there is an infinite variety. By means or this corredion of the errors arifing from the different refrangibility of the rays of light, it is pof- fible to fhorten refrading telefcopes confiderably, and yet leave them equal magnifying powers. The reafon of this is, that the errors arifing from the objed-glafs being removed, thofe which are occafioned by the eye- glafs are inconfiderable : for the error is always in pro¬ portion to the length of the focus in any glafs ; and in very long telefcopes it becomes exceedingly great, bein°- no lefs than -y-g-th of the whole j but in glafles of a few Fig. 6. inches focus it becomes trifling. Refrading telefcopes, which go by the name of Dol/otul'ls,. are therefore now eonltruded in the following manner. Let AB repre- fent an objed-glafs compofed of three lenfes as above defcribed, and converging the rays i, 2, 3, 4, &c. to a very diftant focus as at x. By means of the ’ interpofed lens CD, however, they are converged to one much nearer, as at y, where an image of the objed is formed. The rays diverging from thence fall upon another lens EF, where the pencils are rendered parallel, and an eye placed near that lens would fee the objed magnified and very difiind. To increafe the magnifying power ftill more, however, the pencils thus become parallel are made to fall upon another at GH; by which they are again made to converge to a diftapt focus : but, being intercepted by the lens IK, they are made to meet at the nearer one ssy whence diverging to LM, they are again rendered parallel, and the eye at N fees the obied very diftindly. From an infpedion of the figure it is evident, that Dollond’s telelcope thus conftruded is two telefcopas combined together •> the firft ending with the lens EF, and the fecond with LM. In the firft we do not per¬ ceive the objed itfelf, but the image of it formed at y ; and in the fecond we perceive only the image of that image formed at 5$. Such telefcopes are neverthelefs exceedingly diftind, and reprefent objeds fo clearly as to be preferred, in viewing terreftrial things, even to refledors. The latter indeed have greatly the advan¬ tage in their powers of magnifying, but they are much deficient in point of light. Much more light is loft by refledion than by refradion : and as in thefe telefcopes the light muft unavoidably fuffer two refledions, a great deal of it is loft •, nor is this lofs counterbalanced by the greater aperture which thefe telefcopes will bear, which enables them to receive a greater quantity of light than the refrading ones. The metals of refleding telefcopes alfo are very much fubjed to tarnifti, and require much more dexterity to clean them than the glalfes of refrac- tors j which makes them more troublefome and expen- five, though for making difcoveries in the heavens they 5 are undoubtedly the only proper inftruments which have Optical In- been hitherto conftruded. ftruments. II. The Retlecting Telescope. 1 lie inconveniences arifing from the great length of Newumian refrading telefcopes, before the difcovery of the achro- telefcepe, matic telefcope, are fufhciently obvious j and thefe, to¬ gether with the difficulties occalioned by the different refrangibility of light, induced Sir Ifaac Newton to turn his attention to the fubjed of refledion, and endeavour to icalize the ideas of himfelf and others concerning the poffibility of conftruding telefcopes upon that princi¬ ple.—The inftrument which he contrived is reprefented, fig. 7. where ABCD is a large tube, open at AD and Fig. 7^- clofed at BC, and of a length at leaft equal to the di- ftance of the focus from the metallic fpherical concave fpeculum GH placed at the,end BC. The rays EG, ELI, &c. proceeding from a remote objed PR, interfed one another fomevvhere before they enter the tube, fo that EG, eg, are thofe that come from the lower part of the objed, and///, FH from its upper part : thefe rays after falling on the fpeculum GH, will be refleded. fo as to converge and meet in mn, where they will form a perfed image of the objed.—But as this image can¬ not be feen by the fpedator, they are intercepted by a fmall plane metallic fpeculum KK, interieding the axis - at an angle of 450, by which the rays tending to m n wiil be refleded towards a hole LI/in the fide of the tube, and the image will be lefs diftind, becaufe fome of the rays which would otherwife fall on the concave fpeculum GH, are intercepted by the plane fpeculum : neverthelefs it will appear in a confiderable degree di¬ ftind, becaufe the aperture AD of the tube, and the fpeculum GH, are large. In the lateral hole LL is fix¬ ed a convex lens, whole focus is at S y ; and therefore - this lens will refrad the rays that proceed from any point of the image, fo as at their exit they will be parallel, and thofe that proceed from the extreme points S q will converge after refradion, and form an angle at O, where the eye is placed ; which will fee the image S q, as if it were an oojed through the lens LL 5 confequently the objed will appear enlarged, inverted, bright, and diftind. In LL lenfes of different convexities may be placed, which by being moved nearer to the ima^e or farther from it, would reprefent the objed more or lefs magnified, provided that the furface of the fpeculum GH be of a perfedly fpherical figure. If, in the room of one lens LL, three lenfes be difpofed in the fame manner with the three eye-glaffes of the refrading te¬ lefcope, the objed will appear ered, but lefs diftind than when it is obferved wilh one lens. . account of the pofition of the eye in this telefcope, it New5finder is extremely difficult to dired the inftrument towards any for Newto. objed. Huygens, therefore, firft thought of adding to itnian a fmall refrading telefcope, the axis of which is parallel tofcope- that of the refledor. This is called a Jnder or dire&or. When the Newtonian telefcope is large, and placed upon its lower end to view bodies in great altitudes, the com¬ mon finder can be of no ufe, from the difficulty of get¬ ting the eye to the eye-piece. On this account ^Dr Brewfter propofes (Appendix to Fergufon’s Ledures, vol. ii. p. 478.) to bend the tube of the finder to a right angle, and place a plane mirror at the angular point, fo as to throw the image above the upper part of the tube that 278 OPT Optical In- that the eye-piece of the tinder may be as near as pof- itmments. tibig to the eye-piece of the telefcope. The angular ' ' ’ v" part where the plain mirror is to be fixed, (hould be placed as near as pofTible to the focal image, in order that only a fmall part of the finder may Hand above the tube ; and in this way the eye $an be transferred with the greateft facility from the one eye-piece to the other. The advantages of this conftruftion will be underltood Plate from fig. 3. Plate CCCLXXXIX. where I 1 is part eccrxxxix. 0p a Newtonian telefcope, D the eye-piece, and ABC 3* t]ie finder. The image formed by the objedt-glafs A is retlefted upwards by the plain mirror B, placed at an angle of 450 with the axis of the tube, and the image is viewed with the eye glafs AC* Thofe who have been in the habit of ufing the Newtonian telefcope with the common finder will be fenfible of the convenience 2I, refulting from this contrivance. Magnifying In order to determine the magnifying power of this power of telefcope, it is to be confidered that the plane fpeculum Newtonian ££ fs Gf no ufe in this refpeft. Let us then fuppofe, telefcopes. tjiat Qne ray proceeding from the object coincides with Plate the axis GLIA of the lens and fpeculum j let bbbe. ccclxxxviii another ray proceeding from the lower extreme of the %• s- objett, and pafling through the focus I of the fpeculum KH : this will be refle£ted in the dire&ion bid, paral¬ lel to the axis GL A, and falling on the lens dlud, will be refra&ed to G; fo that GL will be equal to L /, and dG~d I. To the naked eye the object would ap¬ pear under the angle I bi=:b IA ; but by means of the telefcope it appears under the angle dGlA—dlL. — ldi: and the angle Idi is to the angle l bi : : \b : Id; con- fequently the apparent magnitude by the telefcope is to that by the naked eye as the diftance of the focus of the fpeculum from the fpeculum, to the diftance of the focus of the lens from the lens. The following new table of the apertures and magni- fying power of Newtonian telefcopes is taken from the Appendix to Fergufon’s Leftures, vol. ii. p* 480. It is founded on a Newtonian telefcope conftru&ed by Hadley, in which the focal length of the great fpeculum was three feet three inches, and the magnifying power 226. Its aperture varied from three and a half to four and a half inches, according to the want of brightnefs in the obje&s to be examined. The firft column contains the focal length of the great fpeculum in feet, and the fecond its linear aperture in inches, and hundredths of an inch. The third and fourth column* contain Sir Ifaac NeAvton’s numbers, by means of which the aper¬ tures of any kind of reflefting telefcopes may be eafily computed. The fifth column contains the focal length of the eye-glaffes in thoufandths of an inch, and the fixth contains the magnifying power of the inftrument. I C S. Fait 111. Optical in- A New Table of the apertures and riiagnifying power Llhmi-em^ of Newtonian Telefcopes. Focal length of the con¬ cave Ipe- culum. aperture it the con¬ cave fpe¬ culum. lir Ifaac Newton’s numbers. Focal length of the eye- glafe. Magnify¬ ing power. Feet. Inch De Aperture of the fpeculun Focal length of the eye-gl'fs 1 2 3 4 5 6 7 8 9 10 11 12 13 M 16 T7 18 20 21 22 23 24 J-34 2.23 3-79 i-M 6.36 7-51 8.64 9.67 10.44 11.69 12.6 c 14.50 I5-4I 16.25 17.11 17.98 18.82 19.63 20.45 21.24 22.06 22.85 23.62 24.41 j 68' 283 383 476 c62 645 800 946 1084 I345 IS91 1824 Inch. Dec IO0 II9 141 I57 168 178 186 200 212 221 238 251 263 0.107 0.129 0.152 0.168 0.181 0.192 0.200 0.209 0.218 O.222 0.228 0-233 0.238 0.243 0.248 0.252 0.256 0.260 0.264 0.268 0.271 0.274 0.277 0.280 0.283 Times. 56 93 158 214 265 3I3 360 403 445 487 527 566 604 642 677 7I3 749 784 818 852 885 919 952 984 1017 Let TYYT be a brafs tube, in which L / thefe holes he contrived that the light of the different bodies he was comparing fhould fall; while he placed a third piece of pafteboard t C, fe as to prevent the two lights from mixing with one another. Then placing himfelf fometimes on one fide, and femetimes’on the other, but generally on the oppofite fide of this inftru- ment, with refpedl to the light, he altered their pofition till the papers in the two holes appeared to be equally enlightened. This being done, he computed the pro- portion of their light by the fquares of the diftances at which the luminous bodies were placed from the obje&s. If, for inftance, iLe diftances were as three and nine, he concluded that the lights they gave were as nine and eighty-one. Where any light was very faint, he fome¬ times made ufe of lenfes, in order to condenfe it 5 and he enclofed them in tubes or not as his particular appli¬ cation of them required. ' rr Tl o meafure the intenfity of light proceeding from the heavenly bodies, or reflected from any part of the Iky, he contrived an inftrument which refembles a kind of portable camera obfeura. He had two tubes, of which the inner was black, faftened at their loiver ex¬ tremities by a hinge C. At the bottom of thefe tubes F. were two holes, R and S, three or four lines in diame- * £’ ter, covered with twm pieces of fine white paper. The two other extremities had each of them a circular aper¬ ture, an inch in diameter j and one of the tubes confift- ed of two, one of them Hiding into the other, which produced the fame effeft as varying the aperture at the end. men this inftrument is ufed, the obferver has his head, and 'the end of the inftrument C, fe covered that no light can fall upon his eye, befides that which comes through the two holes S and R, while an affift- ant manages the inftrument, and draws out or’ftiortens the tube DE, as the obferver direfts. When the two holes appear equally illuminated, the intenfity of the lights is judged to be inverfely as the fquares of the tubes. In ufing this inftrument, it is neceffary that the ob- je he fuppofes that the moon enlight- calculation. enefj t]ie puri} js as lurninous as the clouds are at a medium. He therefore fuppofed the light of the fun to be equal to that of a whole hemifphere of clouds, or as many moons as would cover the furface of the heavens. But on this Dr Prieftley obferves, that it is true, the light of the fun finning perpendicularly upon any fur- face would be equal to the light rededted from the whole hemifphere, if every part refledfed all the light that fell upon it’, but the light that would in fad! be received from the whole hemifphere (part of it being received obliquely) wrould be only one-half as much as would be received from the whole hemifphere, if every part of it fhone direcfly upon the furface to be illumi¬ nated. In his Remarks, par. 97. Dr Smith demonflrates his method of calculation in the following manner. Plate « the little circle cf dg reprefent the moon’s ecclxxm ^0(jy enlightened by the fun, and the great circle a e b) & fpherical fliell concentric to the moon, and touching the earth ; a b, any diameter of that {hell per¬ pendicular to a great circle of the moon’s body, repre- fented by its diameter c d ; e the place of the fliell re¬ ceiving full moon light from the bright hemifphere /'dg. Now, becaufe the furface of the moon is rough like that of the earth, we may allow that the fun’s rays, incident upon any fmall part of it, with any obliquity, are re- fledted from it every way alike, as if they rvere emitted. And, therefore, if the fegment d f fhone alone, the points a, e, would be equally illuminated by it; and likewife if the remaining bright fegment dg {hone alone, the points b e would be equally illuminated by it. Confequently, if the light at the point a was in- creafed bv the light at £, it would become equal to the full moon light at e. And conceiving the fame transfer to be made from every point of the hemifpherical fur¬ face hbik to their oppofite points in the hemifphere k ae h, the former hemifphere w’ould be left quite dark, and the latter would be uniformly illuminated with full moon light ; anting from a quantity of the fun’s light, which immediately before its incidence on the moon, Would uniformly illuminate a circular plane equal to a great circle of her bodv, called her difk. Therefore the quantities of light being the fame upon both furfaces, ■the denfity of the fun’s incident light is to the denfity of r c S. 2*3 full moon light, as that hemifpherical furface h e k is to Apparatus the faid difk j that is, as any other hemifpherical furface . whofe centre is at the eye, to that part of it which the Lwh"”5 moon’s difk appears to poffefs very nearly, becaufe it ■ -JL— » fubtends but a fmall angle at the eye : that is, as ra¬ dius of the hemifphere to the verfed fine of the moon’s apparent femidiameter, or as 10,000,000 to nob-f-or as 90,400 to 1 taking the moon’s mean horizontal dia¬ meter to be 16' *1". “ Stri&ly fpeaking, this rule compares moon light at the earth with day light at the moon ; the medium of which, at her quadratures, is the fame as our day light j but is lefs at her full in the duplicate ratio of 365 to 366, or thereabout, that is, of the fun’s diflances from the earth and full moon ; and therefore full moon light would be to our day light as about 1 to 90,900, if no rays were loft at the moon. “ Secondly, I fay that full moon light is to any other moon light as the whole difk of the moon to the part that appears enlightened, confidered upon a plane fur- face. For now let the earth be at b, and let dl be Fig. <7, perpendicular to fg, and gm to c d: then it is plain, that g l is equal to dm ; and that g l is equal to a perpendicular fedfion of the fun’s rays incident upon the arch dg which at b appears equal to dm; the eye being unable to diftinguifh the unequal diftances of its parts. In like manner, conceiving the moon’s furface to confift of innumerable phyfical circles parallel toe/r/g, as reprefented at A, the fame reafon holds for every one of thefe circles as for cf dg. It follows then, that the bright part of the furface viftble at b, when reduced to a flat as reprefented at B, by the crefcent p y zw p, will be equal and fimilar to a perpendicular fedtion of all the rays incident on that part, reprefented at C by the crefcent^ y/p. Now the whole difk being in pro¬ portion to this crcfcent, as the quantities of light inci¬ dent upon them ; and the light falling upon every rough particle, being equally rarefied in diverging to the eye at Z, confidered as equidiflant from them all; it follows, that full moon light is to this moon light as the whole difkp dq c \.o the crefcent p dqmp. “ Therefore, by compounding this ratio with that in the former remark, day light is to moon light as the furface of an hemifphere whofe centre is at the eye, to the part of that furface which appears to be poffeffed by the enlightened part of the moon.” 2^2. Mr Miehell made his computation in a much more Mr Mi- fimple and eafy manner, and in which there is much chell’s ch¬ iefs danger of falling into any miftake. Confidering thecu*at*on‘ diftance of the moon from the fun, and that the denfity of the light muft decrcafe in the proportion of the fquare of that diftanee, he calculated the denfity of the fun’s light, at that diftance, in proportion to its denfity at the furface of the fun ; and in this manner he found, that if the moon refleckd all the light it receives from the fun, it would only be the 45,000th part of the light we receive from the greater luminary. Admitting therefore, that moon light is only a 300,000th part of the light of the fun, Mr Michell concludes, that it re- flefts no more than between the 6th and 7th part of what falls upon it. Count Rumford, has c on fir u fled a photometer, in Rurnford’s which the fhadows, inflead of being thrown upon a photome- paper fpread out upon the wainfeot, or fide of theter* room, are projected upon the infide of the back part N n 2 of ♦ 284 O ,P T Apparatus of a wooden box inches wide, io^ inches long, M f°r . n and 3:j- inches deep, in the clear. The light is admitted Light118 it through two horizontal tubes in the front, placed u—fo as to form an angle of 6o° 5 their axes meeting at the centre of the field of the inftrument. In the middle of the front of the box, between thefe two tubes, is an Plate opening through which is viewed the field of the pho- ccclxxxix. tometer (fee fig. 5.). This field is formed of a piece of fig’ 5* white paper, which is not faftened immediately upon the infide of the back of the box, but is palled upon a fmall pane of very fine ground glafs-, and this glafs, thus covered, is let down into a groove, made to receive it, in the back of the box. The whole infide of the box, except the field of the inllrument, is painted of a deep black dead colour. To the under part of the box is fitted a ball and focket, by which it is attached to a Hand which fupports it } and the top or lid of it is fitted with hinges, in order that the box may be laid quite open, as often as it is neceflary to alter any part of the machinery it contains. The count had found it very inconvenient to com¬ pare two (hadows proje£led by the fame cylinder, as thefe were either neeeflarily too far from each other to be compared with certainty, or, when they were near¬ er, were in part hid from the eye by the cylinder. To remedy this inconvenience, he now makes ufe of two cylinders, which are placed perpendicularly in the bot¬ tom of the box juft defcribed, in a line parallel to the back part of it, diftant from this back 2TV inches, and from each other 3 inches, meafuring from the centres of the cylinders ; when the two lights made ufe of in the experiment are properly placed, thefe trvo cylinders projedl four ftiadovs upon the white paper upon the in¬ fide of the back part of the box, or the field of the in¬ ftrument 5 two of which ftiadows are in conta£l, pre- cifely in the middle of that field, and it is thefe two alone that are to be attended to. To prevent the at¬ tention being diftrafled by the prefence of unneceffary objects, the two outfide ftiadows are made to difappear j which is done by rendering the field of the inftrument fo narrow, that they fall without it, upon a blackened furface, upon which they are not vifible. If the cy¬ linders be each of an inch in diameter, and inches in height, it will be quite fufficient that the field be 2Tu- inches wide \ and as an unneceflary height of the field is not only ufelefs, but difadvantageous, as a large furface of white paper not covered by the ftiadows pro¬ duces too ftrong a glare of light, the field ought not to be more than T?o- of an inch higher than the tops of the cylinders. That its dimenfions, however, may be occafionally augmented, the covered glafs fhould be made 54- inches long, and as wide as the box is deep, viz. 34:*inches j fince the field of the inftrument can be reduced to its proper fize by a fcreen of black pafteboard, interpofed before the anterfor furface of this covered glafs, and refting immediately upon it. A hole in this pafteboard, in the form of an oblong fquare, lTV inch wide, and tivo inches high, determines the dimenfions, and forms the boundaries of the field. This fcreen fhould be large enough to cover the 'whole infide of the back of the box, and it may be fixed in its place by means of grooves in the fides of the box, into which it may be made to enter. The pofition of the opening above mentioned is determined by the height of the cylinders j the top of it being ^ of an inch higher tb,an the tops of the cylinders 3 and as the height of it I C S. Part Ilf, is only two inches, while the height of the cylinders is Apparatus 2-jV inches, it is evident that the ftiadows of the lower for parts of the cylinders do not enter the field. No in- Mrafuring convenience arifes from that circumftance 3 on the eon- . trary, feveral advantages are derived from that arrange- ment. That the lights may be placed with facility and pre- cifion, a fine black line is drawn through the middle of the field, from the top to the bottom of it, and another (horizontal) line at right angles to it, at the height of the top of the cylinders. When the tops of the ftiadows touch this laft-mentioned line, the lights are at a proper height 3 and farther, when the two ftiadows are in con¬ tact with each other in the middle of the field, the. lights are then in their proper directions. We have faid that the cylinders, by which the ftia¬ dows are projefted, are placed perpendicularly in the bottom of the box 3 but as the diameters of the ftiadows of thefe cylinders vary in fome degree, in proportion as the lights are broader or narrower, and as they are brought nearer to or removed farther from the photo¬ meter, in order to be able in all cafes to bring thefe ftia¬ dows to be of the fame diameter, which is very advan¬ tageous, in order to judge with greater facility and cer* tainty when they are of the fame denfity, the count renders the cylinders moveable about their axes, and adds to each a vertical wing of an inch wide, of • an inch thick, and of equal height with the cylinder itfelf, and firmly fixed to it from the top to the bot¬ tom. This wing commonly lies in the middle of the fliadow of the cylinder, and as long as it remains in that fituation it has no effeft whatever ; but when it is ne- ceffary that the diameter of one of the ftiadows be in- creafed, the correfponding cylinder is moved about its axis, till the wing juft defcribed, emerging out of the fhadow, and intercepting a portion of light, brings the ftiadow projeCled upon the field of the inftrument to be of the width or diameter required. In this opera¬ tion it is always neceflary to turn the cylinder outwards, or in fuch a manner that the augmentation of the width of the ftiadow may take place on that fide of it which is oppofite to the ftiadow correfponding to the other light. The neceftity for that precaution will appear evident to any one who has a juft idea of the inftrument in queftion, and of the manner of making ufe of it. They are turned likewife without opening the box, by taking hold of the ends of their axes, which projefl below its bottom. As it is abfolutely neceflary that the cylinders ftiould conftantly remain precifely perpendicular to the bottom of the box, or parallel to each other, it will be beft to conftrufl them of brafs 3 and, inftead of fixing them im¬ mediately to the bottom of the box (which, being of wood, may warp), to fix them to a ftrong thick piece of well-hammered plate brafs 3 which plate of brafs may be afterwards faftened to the bottom of the box by means of one ftrong ferew. In this manner two of the count’s beft inftruments are conftrufted; and, in order to feeure the cylinders ftill more firmly in their vertical pofitions, they are furniftied with broad flat rings, or projeftions, where they reft upon the brafs plate 3 which rings are ^ of an inch thick, and equal in diameter to the projection of the wing of the cylinder, to the bot¬ tom of which they afford a firm fupport. Thefe cy¬ linders are likewife forcibly puftied, or rather pulled, againfi Part III. OPT Apparatus agaiafl; the brafs plate upon which they reft, by means for of comprefled fpiral fprings placed between the under Measuring piate and the lower ends of the cylinders. L ^1' i Of whatever material the cylinders be conftrufted, and whatever be their forms or dimenfions, it is abfolutely neceffary that they, as -well as every other part of the photometer, except the field, ftiould be well painted of a deep black dead colour. In order to move the lights to and from the photo¬ meter with greater eafe and precifion, the obferver ftrould provide twro long and narrow, but very ftrong and fteady, tables ; in the middle of each of which there is a ftraight groove, in which a Aiding carriage, upon which the light is placed, is drawn along by means of a cord which is fattened to it before and be¬ hind, and which, palling over pulleys at each end of the table, goes round a cylinder ; which cylinder is fur- nilhed with a winch, and is fo placed, near the end of the table adjoining the photometer, that the obferver can turn it about, without taking his eye from the field of the inftrument. Many advantages are derived from this arrangement: Firft, the obferver can move the lights as he finds ne- ceffary, without the help of an aftiftant, and even with¬ out removing his eye from the fhadows ; fecondly, each light is always precifely in the line of direftion in which it ought to be, in order that the ftiadows may be in con- ta£l in the middle of the vertical plane of the photo¬ meter $ and, thirdly, the Hiding motion of the lights being perfectly foft and gentle, that motion produces little or no effect upon the lights themfelves, either to increafe or diminilh their brilliancy. Thefe tables muft be placed at an angle of 60 de¬ grees from each other, and in fuch a fituation, with re- fpeft to the photometer, that lines drawn through their middles, in the direffion of their lengths, meet in a point exa&ly under the middle of the vertical plane or field of the photometer, and from that point the diftan- ces of the lights are meafured •, the fides of the tables being divided into Engliflr inches, and a vernier, Ihew- ing tenths of inches, being fixed to each of the Hiding carriages upon which the lights are placed, and which are fo contrived that they may be raifed or lowered at pleafure ; fo that the lights may be always in a hori¬ zontal line with the tops of the cylinders of the photo¬ meter. In order that the two long and narrow tables or plat¬ forms, juft defcribed, may remain immoveable in their proper pofitions, they are both firmly fixed to the Hand which fupports the photometer ", and, in order that the motion of the carriages which carry the lights may be as foft and gentle as poflible, they are made to Hide up¬ on parallel brafs wires, 9 inches afunder, about r— of an inch in diameter, and well poliftied, which are ftretdi¬ ed out upon the tables from one end to the other. Plate The ftruflure of the apparatus will be clearly under- ccclxxxixflood by a bare infpeflion of Plate CCCLXXXIX. %• 5- fig. 5. is a plan of the infide of the box, and the adjoin¬ ing parts of the photometer. Fig. 6. Plan of the two tables belonging to the photometer. Fig. 7. The box of the photometer on its ftand. Fig. 8. Elevation of the photometer, with one of the .tables and carriages. Having fufficiently explained all the effential parts ef this photometer, it remains for us to give feme ac- I C S. 285 count of the precautions ncceffary to be obferved in Apparatus ufmg it. And, firft, with refped to the diftance at ^ . which lights, whofe intenfities are to be compared, Light. S fhould be placed from the field of the inftrument, the ■ ^ ‘ ingenious and accurate inventor found, that when the weakeft of the lights in queftion is about as ftrong as a common wax candle, that light may moft advantageoufly be placed from 30 to 36 inches from the centre of the field ; and when it is weaker or ftronger, proportionally nearer or farther off. When the lights are too near, the fhadows will not be well defined ; and when they are too far off, they will be too wreak. It will greatly facilitate the calculations neceffary in drawing conclufions from experiments of this kind, if fome fteady light, of a proper degree of ftrength for that purpofe, be affumed as a ftandard by which all others may be compared. Our author found a good Argand’s lamp much preferable for this purpofe to any other lamp or candle whatever. As it appears, he fays, from a number of experiments, that the quantity of light emitted by a lamp, which burns in the fame manner with a clear flame, and without fmoke, is in all cafes as the quantity of oil confumed, there is much reafon to fuppofe, that, if the Argand’s lamp be fo ad- jufted as always to confume a given quantity of oil in a given time, it may then be depended on as a juft ftand¬ ard of light. In order to abridge the calculation neceffary in thefe- inquiries, it will always be advantageous to place the ftandard-lamp at the diftance of 100 inches from the photometer, and to affume the intenfity of its light at its fource equal to unity ; in this cafe (calling this ftand¬ ard light A, the intenfity of the light at its fource =zxzzi, and the diftance of the lamp from the field of the photometer =ot=iioo), the intenfity of the il- X lumination at the field of the photometer (= — be expreffed by the fra&ion -^i — toboo ? and there- TTJo lative intenfity of any other light which is compared with it, may be found by the following proportion : Call¬ ing this light B, putting y=z its intenfity at its fource, and n — its diftance from the field of the photometer, expreffed in Engliftr inches, as it is or, in- ftead of —j, writing its value it 'will be =r To^oo '■> and confequently y is to I as «2 is to 10000 5 or the intenfity of the light B at its fource, is to the intenfity of the ftandard light A at its fource, as the- fquare of the diftance of the light B from the middle of the field of the inftrument, expreffed in inches, is to IOOOO ; and hence it is y— . J 10000 Or, if the light of the fun, or that of the moon, be compared with the light of a given lamp or candle C,. \ the refult of fuch comparifon may be beft expreffed in words, by faying, that the light of the celeftial luminary in queftion, at the furface of the earth, or, which is the fame thing, at the field of the photometer, is equal to the light of the given lamp or candle, at the dijiance found by the experiment; or, putting a — the intenfity of the light of this lamp C at its fource, and p — its , diftance. 3 2 86 OPT Apparatus for Meafuring Light. difiance, in inches, from the field, when the fhadows correfponding to this li-^ht, and that correfponding to the celeflial luminary in quellion, are found to be of equal denfities, and putting ssrz the dntenfity of the rays of the luminary at the furfaee of the earth, the re- fult of the experiment may be exprefled thus, z-rr— j or the real value of n being determined by a particular experiment, made exprefsly for that purpofe with the fiandard lamp, that value may be written inftead of it. When the fiandard lamp itfelf is made ufe of, inftead of the lamp C, then the value of A will be I. The count’s firft attempts with his photometer were to determine how far it might be poftible to afeertain, by diredi experiments, the certainty of the affumed law of the diminution of the intenfity of the light emitted by lum’nous bodies j namely, that the intenfity of the light is evervwhere as the Squares of the diftances from the luminous body inverfely. As it is obvious that this law can hold good only when the light is propagated through perfedtly tranfparent fpaces, fo that its inten¬ fity is weakened merely by the divergency of its rays, he inftituted a fet of experiments to afeertain the tranf- parency of the air and other mediums. With this view, two equal wax candles, well trim¬ med, and which were found, by a previous experiment, to burn with exadlly the fame degree of brightnefs, were placed together, on one fide, before the photome¬ ter, and their united light was counterbalanced by the light of an Argand’s lamp, well trimmed, and burning very equally, placed on the other fide over againft them. The lamp was placed at the diftance of 100 inches from the field of the photometer, and it was found that the two burning candles (which were placed as near toge¬ ther as pofiible, without their flames affedling each other by the currents of air they produced) were juft able to counterbalance the light of the lamp at the field of the photometer, when they were placed at the diftance of 60.8 inches from that field. One of the candles being now taken away and extinguifhed, the other was brought nearer to the field of the inftru- ment, till its light tvas found to be juft able, fingly, to counterbalance the light of the lamp ; and this was found to happen when it had arrived at the dillance of 43.4 inches. In this experiment, as the candles burnt with equal brightnefs, it is evident that the intenfities of their united and fingle lights were as 2 to x, and in that proportion ought, according to the affumed theory, the fquares of the diftances, 60.8 and 43.4, to be •, and, in faft, 60.8*^=3696.64 is to 43.4*=!883.56 as 2 is to I very nearly. Again, in another experiment, the diftances were, With two candles r= 54 inches. Square =2916 With one candle = 38.6 - =1489.96 Upon another trial, With two candles = 54.6 inches. Square rr 2981.16 With one candle = 39.7 - =1576.09 And, in the fourth experiment, With two candles =r 58.4 inches. Square = 3410 36 With one candle = 42.2 - - = 1780.84 And, taking the mean of the refults of thefe four experiments, 1 c s. Part in. In the experiment N° 1. 3606.64. N° 2. 2916 N° 3. 2981.16 N° 4. 3410.56 Squares of the d lit antes Apparatus With two candles. With one candle. for 1883.56 Meafiiring 1489.96 Lisht- I576.OQ 1780.84 4),3°04-36 4)673°-45 Means 3251.09 and 1682.61 which again are very nearly as 2 to 1. With regard to thefe experiments, it may be ob- ferved, that were the reliftance of the air to light, or the diminution of the light from the imperfect tranf- parency of air, fenfible within the limits of the incon- iiderable diftances at -which the candles were placed from the photometer, in that cafe the diftance of the two equal lights united ought to be, to the diftance of one of them fingle, in a ratio lei's than that of the fquare root of 2 to the fquare root of I. For if the intenfity of a light emitted by a luminous body, in a /pace void of all reftflance, be diminifhed in the proportion of the fquares of the diftances, it muft of neceflity be dimi- niftied in a ftilt higher ratio when the light pafies through a refifting medium, or one which is not perfectly tranf- parent ; and from the difference of thofe ratios, name¬ ly, that of the fquares of the diftances, and that other higher ratio found by the experiment, the refiftance of the medium might be afeertained. This he took much pains to do with refpeft to air, but did not fucceed ; the tranfparency of air being fo great, that the dimi¬ nution which light fuffers in pafling through a few inches, or even through feveral feet of it, is not fen¬ fible. Having found, upon repeated trials, that the light of a lamp, properly trimmed, is incomparably more equal than that of a candle, whofe wick, continually growing longer, renders its light extremely fluff uating, he fub- ftituted lamps to candles in thefe experiments, and made fuch other variations in the manner of conducting them as he thought bid fair to lead to a difeovery of the refiftance of the air to light, were it poflible to ren¬ der that refiftanee fenfible within the confined limits of his machinery. But the refults of them, fo far from af¬ fording means for afeertaining the refiftance of the air to light, do not even indicate any refiftanee at all ; on the contrary, it might almoft be inferred, from fome of them, that the. intenfity of the light emitted by a lu¬ minous body in air is diminilhed in a ratio lefs than that of the fquares of the diftances •, but as fuch a conclu- fion would involve an evident abfurdity, namely, that light moving in air, its abfolute quantity, inftead of be¬ ing diminifhed, aftually goes on to increafe, that con- clufion can by no means be admitted. Why not ? Theories muft give place to fafts ; and if this fad can be fairly afeertained, inftead of rejecting the conclufion, we ought certainly to redify our no¬ tions of light, the nature of which we believe no man fully comprehends. Who can take it upon him to fay, that the fubftance of light is not latent in the at- mofphere, as heat or caloric is now acknowledged to be latent, and that the agency of the former is not called forth by the paffage of a ray through a portion of air, as the agency of the latter is known to be excited by PartlH. OPT Apparatus by the combination of oxygen with any combuftible f°r. fubftance ? ^Li ht"^ ‘noen^,us author’s experiments all cpnfpired to .1^ i fhew that the refiftance of the air to light is too incon- fiderable to be perceptible, and that the aiTumed law of the diminution of the intenfity of light may be depend¬ ed upon with fafety. He admits, however, that means may be found for rendering the air’s refinance to light apparent •, and he feems to have thought of the very means which occurred for this purpofe to M. de Sauf- 274 lure. Contrivan- That eminent philofopher, wifiling to afcertain the ces of Sauf-tranfparency of the atmofphere, by meafuring the di- flire' fiances at which determined objedls ceafe to be vifible, perceived at once that his end would be attained, if he fhould find objects of which the difappearance might be accurately determined. Accordingly, after many trials, he found that the moment of diiappearance can be obferved with much greater accuracy when a black object is placed on a white ground, than when a white objedl is placed on a black ground ; that the accuracy was ftill greater when the obfervation was made in the fun than in the (hade ; and that even a ftill greater de¬ gree of accuracy was obtained, when the white fpace furrounding a black circle, was itfelf furrounded by a circle or ground of a dark colour. This laft circum- ftance was particularly remarkable, and an obfervation quite new. If a circle totally black, of about two lines in diame¬ ter, be fattened on the middle of a large ftieet of paper or pafteboard, and if this paper or pafteboard be pla¬ ced in fuch a manner as to be expofed fully to the light of the fun, if you then approach it at the diftance of three or four feet, and afterwards gradually recede from it, keeping your eye conftantly direded towards the black circle, it will appear always to decreafe in fize the farther you retire from it, and at the diftance of 33 or 34 feet will have the appearance of a point. If you continue ftill to recede, you will fee it again enlarge it¬ felf; and it will feem to form a kind of cloud, thedark- nefs of which decreafes more and more according as the circumference becomes enlarged. The cloud will ap¬ pear ftill to increafe in fize the farther you remove from it; but at length it will totally difappear. The mo¬ ment of the dilappearanee, however, cannot be accurate¬ ly afeertained; and the more experiments were repeated, the more were the refults different. M. de Sauffure, having refieded for a long time on the means of remedying this inconveniency, faw clear¬ ly, that as long as this cloud took place, no accuracy could be obtained ; awl be difeovered that it appeared in confequence of the contrail formed by the white parts which were at the greateft diftance from the black circle. He thence concluded, that if the ground was left white near this circle, and the parts of the pafte¬ board at the greateft diftance from it were covered with a dark colour, the cloud would no longer be vifible, or at leaft almoft totally difappear. This conjedure was confirmed by experiment. M. de Sauffure left a white fpace around the black circle equal in breadth to its diameter, by placing a circle of black paper a line in diameter, on the middle of a ivhite- circle three lines in diameter, fo that the black circle was only furroundeu by a white ring a line in breadth. I he whole was patted upon a green ground. A green 4 ICS. 287 colour was chofen, becaufe it was dark enough to make Apparatus the cloud difappear, and the eafieft to be procured. fot. The black circle furrounded in this manner with white on a green ground, difappeared at a much lefs' ' • diftance than when it was on a white ground of a large fize. If a perfedly black circle, a line in diameter, be patted on the middle of a white ground expofed to the open light, it may be obferved at the diftance of from 44 t0 45 fee' i but T this circle be furrounded by a white ring a line in breadth, while the reft of the ground is green, ail fight of it is loft at the diftance of only 15T feet. According to thefe principles M. de Saufl'ure deline¬ ated feveral black circles, the diameters of which in- creafed in a geometrical progreffion, the exponent of which was His fmalleft circle was -j- or 0.2 of a line in diameter ; the lecond, 0.3 ; the third, 0.45 ; and fo on to the fixteenth, which was 87.527, or about 7 inches 34 lines. Each of thefe circles was fugrounded by a white ring, the breadth of which was equal to the diameter of the circle, and the whole was palled on a , green ground. M. de Sauffure, for his experiments, feledled a ftraight road or plain of about 1200 or 1500 feet in circumfer¬ ence, which towards the north was bounded by trees or an afeent. Thofe who repeat them, however, mutt pay attention to the following remarks : When a perfon retires backwards, keeping his eye conftantly fixed on the pafteboard, the eye becomes fatigued, andioon ceafes to perceive the circle ; as foon therefore as it ceafes to be diftinguilhable, you muft fuffer your eyes to reft ; not, hoAvever, by {hutting them, for they would when again opened be dazzled by the light, but by turning them gradually to fome lefs illuminated objedl in the horizon. When you have done this for about half a minute, and again diredled your eyes to the pafteboard, the circle will be again vifible, and you muft continue to recede till it difappear once more. You muft then let your eyes reft a fecond time in order to look at the circle again, and continue in this manner till the circle becomes aflually invifible. If you with to find an accurate exprefticn for the want of tranfparency, you muft employ a number of circles, the diameters of which increafe according to a certain progreflion ; and a comparifon of the diftances at which they difappear will give the law according to which the tranfparency of the atmofphere decreafes at different diftances. If you wifh to c mpare the tranf¬ parency of the atmofphere on two days, or in two dif¬ ferent places, two circles will be fufticient for the expe¬ riment. According to thefe principles, M. de Sauffure caufed to be prepared a piece of white linen doth eight feet fquare. In the middle of this fquare he fewed a per- fed circle, two feet in diameter, of beautiful black wool; around this circle he left a white ring two feet in breadth, and the reft of the fquare was covered with pale green. In the like manner, and of the fame materials, he prepared another fquare ; which was, however, equal to only r- of the fize of the former, fo that each fide of i» wa^ 8 inches ; the black circle in the middle was two inches in diameter, and the white fpace around the circle was 2 inches alfo. If two fquares of this kind be fulpended vertically and 288 Apparatus and parallel to each other, fo that they may be both il- ^ luminated In an equal degree by the fun ; and if the at- Ligl]lt & mofphere, at the moment w^en the experiment is made, v ii i» v—. .< be perfectly tranfparent, the circle of the large fquare, which is twelve times the fize of the other, muft be feen at twelve times the diltance. In M. de Sauflure’s ex¬ periments the fmall circle difappeared at the diftance of 314 feet, and the large one at the diftance of 3588 feet, whereas it ihould have difappeared at the diftance of 3768. The atmofphere, therefore, was not perfeftly tranfparent. This arofe from the thin vapours which at that time were floating in it. M. de Saulfure, calls his inflrument a diaphunometer; but it ferves one of the purpofes of a photometer. From a number of experiments made with the photo¬ meter, Count Rumford found, that, by pafling through a pane of fine, clear, well polilhed glafs, fuch as is com¬ monly made ufe of in the conftruftion of looking-glaf- fes, light lofes .1973 of its whole quantity, i. e. of the quantity which impinged on the glafs •, that when light is made to pafs through two panes of fuch glafs Hand¬ ing parallel, but not touching each other, the lofs is .3184 of the whole ; and that in pafling through a very^ thin, clear, colourlefs pane of window-glafs, the lofs is only .1263. Hence he infers, that this apparatus might be very ufefully employed by the optician, to determine the degree of tranfparency of glafs, and di- refl his choice in the provifion of that important article of his trade. The lofs of light when reflefted from the very belt plain glafs mirror, the author afcertained, by five experiments, to be ^d of the whole which fell upon the mirror. An ingenious photometer lias alfo been invented by Profeffor Leflie, and fully defcribed in his celebrated work on Heat, to which we muft refer the reader for a complete defcription of this inftrument. It meafures the calorific effedt of heat, and is founded upon this princi¬ ple, “ that if a body be expofed to the fun’s rays, it will, in every poflible cafe, be found to indicate a mea- fure of heat exadtly proportioned to the quantity of light which it has abforbed.” See on Heat, p. 103. Chap. II. On the method of forming the Lenfes and Specula, of RefraETing and Reflecting Tele- fcopes. Sect. I. On the Method of grinding and polifhing Lenfes. Having fixed upon the proper aperture and focal ing lenfes. diftance of the lens, take a piece of (beet copper, and ftrike a fine arch upon its furface, with a radius equal to OPTICS. Part III. half that diftance, if it is to be plano-convex, and let the Method of ^75 Leflie’sphO' tometer. 27 S 'On grind- length of this arch be a little greater than the given Grinding aperture. Remove with a file that part of the copper^ U which is without the circular arch, and a convex gage^^^^j will be formed. Strike another arch with the fame ra- 277 dius, and having removed that part of the copper which formation is within it, a concave gage will be obtained. Prepare°[the two circular plates of brafs, about T~ of an inch thick,^eS‘ and half an inch greater in diameter than the breadth of the lens, and folder them upon a cylinder of lead of the fame diameter, and about an inch high. Thefe Formation tools are then to be fixed upon a turning lathe, and one of the tools, of them turned into a portion of a concave fphere, fo as to fuit the convex gage *, and the other into a portion of a convex fphere, fo as to anfwer the concave gage. After the furfaces of the brafs plates are turned as ac¬ curately as poflible, they muft be ground upon one ano¬ ther, alternately, with flour emery ; and when the two furfaces exa6tly coincide, the grinding tools will be ready for ufe‘ . . . *19 Procure a piece of glafs whofe difperfive power is as Formation fmall as poflible, if the lens is not for achromatic inftru-of the glafs. ments, and whofe furfaces are parallel; and by means of a pair of large fciffars or pincers, cut it into a circular ftiape, fo that its diameter may be a little greater than the required aperture of the lens. When the rotighnefs is removed from its edges by a common grindftone (a), it is to be fixed with black pitch to a wooden handle of a fmaller diameter than the glafs, and about an inch high, fo that the centre of the handle may exaflly coin¬ cide with the centre of the glafs. 2g0 The glafs being thus prepared, it is then to be ground Mods of with fine emery upon the concave tool, if it is to begda^g- convex, and upon the convex tool, if it is to be concave. To avoid circumlocution, we ftiall fuppofe that the lens is to be convex. The concave tool, therefore, which is to be ufed, muft be firmly fixed to a table or bench, and the glafs wrought upon it with circular ftrokes, fo that its centre may never go beyond the edges, of the tool. For every 6 circular ftrokes, the glafs ftiould receive 2 or 3 crofs ones along the diameter of the tool, and in dif¬ ferent dire&ions. When the glafs has received its pro¬ per ihape, and touches the tool in every point of its fur- face, which may be eafily known by infpeftion, the eme¬ ry is to be walked aivay, and finer kinds (b) fuccefiivcly fubftituted in its room, till by the fame alternation of circular and tranfverfe ftrokes, all the fcratchesand afpe- rities are removed from its furface. After the fineft emery has been ufed, the roughnefs which remains may be taken away, and a flight polifti fpperinduced by grind¬ ing the glafs with pounded pumice-ftone, in the fame manner as before. While the operation of grinding is going on, the convex tool Ihould, at the end of every five (a) When the focal diftance of the lens is to be Ihort, the furface of the piece of glafs ihould be ground upon a common grindftone, fo as to fuit the gage as nearly as poffible ; and the plates of brafs, before they are foldered on the lead, Ihould be hammered as truly as they can be done into their proper form. By this means much labour will be faved both in turning and grinding. (b) Emery of different degrees of finenefs may be made in the following manner. Take five or fix clean vef- fels, and having filled one of them with water, put into it a confiderable quantity of flour emery. Stir it well with a piece of wood, and after Handing for 5 feconds pour the Avater into the fecond veffel. After it has flood about 12 feconds, pour it out of tins into a third veffel, and fo on with the reft j and at the bottom of each veffel will be found emery of different degrees of finenefs, the coarfeft being in the firft veffel, and the fineft in the laft. f’lf/ 1 OPTIC S PL. 17/-J fYY'AXXV * C) P TT C S . PLATUCCCLXXVH. S-Afi/c/t-eM' s-cnlps. s/zzAst/cT? OPTICS PLATE CCCLXXX. WXr~ dly, The Chriftian emperors do indeed feem to con¬ demn the fuperftition and idolatry of thofe o ho were ftill for confulting oracles 5 but the edicts of thofe princes do not prove that oracles actually exifted in their times, any more than that they ceafed in conlequence of their laws. It is certain that they were for the moft part extinct before the converfion of Conftantine. e\thli], Some Epicureans might make a jef of this fu- p erf it ion : however the Epicurean philofopher Celfus, in the fecond century of the church, was for crying up the excellency of feveral oracles, as appears at large from Origen’s feventh book againft him. ORAiA, certain folemn facrifices of fruits which were offered in the four feafons of the year, in order to obtain mild and temperate weather. T hey were offered to the goddeffes who prefided over the feafons, %vho attended upon the fun, and who received divine worfhip at Athens. ORAL, fomething delivered by word of mouth, without being committed to writing ; in which fenfe we fay oral law, oral tradition, &c. ORAN, a very ftrong and important towngf Africa, in Barbary, and in the kingdom of Tremecen, with feveral forts, and an excellent harbour. It is feated partly on the fide of a hill, and partly on a plain, about a ftonecaft from the fea, almoft oppofite to Car- thagena in Spain. It is about a mile and a hall in circumference, and well fortified, but commanded by the adjacent hills. It was taken by the Spaniards in 1509, and retaken by the Algerines in 1708 •, but in 1732 the Spaniards became mailers of it, and have con¬ tinued fo ever fince. E. Long. o. 8. N. Lat. 36. 2. ORANG outang. See Simia, Mammalia ORANGE, a famous city, and capital of a province of the fame name, united to Dauphiny, with a univerfity and a biihop’s fee, fuffragan of Arles. It is feated in a fine large plain, watered by a vaft number of little rivulets on the eaft fide of the river Rhone. It is a very large ancient place, and was confiderable in the time of the Romans, who adorned it with feveral build¬ ings, of which there are ftill fome ruins left, particularly of an amphitheatre, and a triumphal arch, which is almoft entire, dedicated to Marius. This town was formerly much larger than it is at prefent, as appears from the traces of the ancient walls. 'Ihe wall was in 1682 entirely demoliftied by order of Louis XIV. and the inhabitants were expofed to the fury of the foldiers. The town was reftored to King William by the treaty of Ryfwiek *, but after his death the French took it again, and expelled the Proteftant inhabitants. By the the treaty of Utrecht it was confirmed to the crown of France, though the title is ftill retained in the houfe of Naffau. The title was firft introduced into the family of Naffau, by the marriage of Claude de Chalons, the prince of Orange’s fifter, with the count of Naifay, 1 530. The principality is a very fmall diftrifl, it being only twelve miles in length and nine in breadth, and the revenue amounts to about 5000I. a year. The country is pleafant, and abounds with corn and fruit, but is ex¬ pofed to violent winds. E. Long. 4. 49. N. Lat. 44. 9. Maurice Prince of ORANGE. See MAURICE. 0-RANGE River, alfo known by the name of the P p 2 Great ORA [ 300 ] ORA Orange. Great river, is fituated in fouthern Africa, and is of v confiderable extent. It feetns to take its rife about S. Lat. 30°, and E. Long. 28° from Greenwich, and joins the fea, after a weft by north courfe for a number of leagues, between the great and little Namaquas, two tribes fuppofed to be of the fame origin with the Hot¬ tentots. There are high cataradts in it, and it is fubjedt to inundations like the Nile. Carnelians, calcedo- nies, agates and variolites are found upon the (hores. The rains in the great mountains along the foot of which the Orange river runs, colledting their ftreams in its paffage, commence in the month of November, and caufe the inundations to take place towards the Namaqua country in the month of December. The naufeous cuftom of greafing the fkin, from the great fcarcity of water in many parts of South Africa, is rendered un- neceifary among the people who inhabit the banks of this grand river 5 and of confequence they exhibit none of that filthy appearance which is charadteriftic of the Hottentots on the ikirts of the colony. OfiANGE-Tree, in Botany. See Citrus, Botany Index.-—Orange flowers are juftly efteemed one of the fineft perfumes; and though little ufed in medicine, yet the water diftilled from them is accounted ftomachic, cordial, and carminative. The fruit is cooling, and good in feverilh diforders, and particularly in diarrhoeas. Orange-peel is an agreeable aromatic, proper to repair and ftrengthen the ftomach, and gives a very grateful flavour to any infufions or tindlures into whofe eom- pofitions it enters. It is particularly ufeful in pre¬ parations of the bark : gives an agreeable warmth to the infufion ; and, according to Dr Percival, confider- ably increafes its virtue. In the Philofophical Tranfadtions, N°il4. there is a very remarkable account of a tree Handing in a grove near Florence, having an orange flock, which had been fo grafted upon, that it became in its branches, leaves, fjowers, and fruit, three-formed : fome emulating the orange, fome the lemon or citron, and fome partaking of both forms in one; and what was very remarkable was, that thefe mixed fruits never produced any perfedl feeds: fometimes there were no feeds at all in them, and fometimes only a few empty ones. ORANGE-Dew, a kind of dew which falls in the fpring time from the leaves of orange and lemon trees, which is extremely fine and fubtile. M. de la Hire ob- ferving this, placed fome flat pieces of glafs under the leaves to receive it: and having procured fome large drops of it, was defirous of difeovering what it was. He foon found that it was not merely an aqueous fluid, becaufe it did not evaporate in the air ; and that it was not a refin, becaufe it readily and perfe&ly mixed with water: it was natural then to fuppofe it a liquid gum ; but neither did this, on examination, prove to be the cafe ; for being laid on paper, it did not dry as the other liquid gums do. Its anfwering to none of thefe characters, and its being of the confiftence of honey, and of a fweet fugar-like tafte, gave a fufpicion of its being a kind of manna; and whatever in the other trials had proved it not a refin, a gum, &c. all equally tends to prove that it is this fubfianee. ORANGE, Sea, in Natural Hijlory, a name given by Count Marfigli to a very remarkable fpecies of marine fubftance, which he denominates a plant. It is tough and firm in its ftruCture, and in many things refembles 4 the common fucus ; but inftead of growing in the Orange branched form which the generality of thole fubftan- Oration, ces have, it is round and hollow, and in every refpeCt '“■'V'—' refembles the fhape of an orange. It has, by ivay of root, fome exceeding fine filamehts, which fallen them, felves to the rocks, or to fhells, ft ones, or any thing elfe that comes in the way. From thefe there grows no pedicle ; but the body of the orange, as it is called, is faftened by them to the rock, or other folid fub¬ ftance. The orange itfelf is ufually of about three or four inches in diameter; and while in the fea, is full of water, and even retains it when taken up. In this ftate it frequently weighs a pound and a half; but when the water is let out, and it is dried, it becomes a mere membrane, weighing fcarce any thing. It is beft preferved, by fluffing it with cotton as foon as the water is let out of it, and then hanging it up to dry. Its furface is irregular and rough, and its colour a dulky green on the outfide, and a clearer but fome- what bluifh green within ; and its thicknefs is about an eighth part of an inch. When viewed by the mi- crofcope, it is feen to be all over covered with fmall glandules, or rather compofed of them ; for they Hand fo thick one by another as to leave no fpace between, and feem to make up the whole fubftance; fo that it appears very like the rough lhagreen Ikin ufed to co¬ ver toys. Thefe are indeed fo many hollow duds, through which the fea-water finds a palfage into the globe formed by this Ikin, and by this means it is kept always full and diftended ; on cutting it with a pair of feiflars, the water immediately runs out, and the fkins collapfe ; but there is fomething extremely re¬ markable in this, for the whole fubftance, near the wounded place, is in motion, and feems as if alive, and fenfible of the wound. The glandules are found full of water, and refembling fmall tranfparent bottles; and what goes to the ftrudure of the plant befide thefe, is an affemblage of a vaft number of filaments, all which are likewife hollow, and filled with a clear and tranfpa¬ rent fluid. There is another fubftance of this kind, mentioned and deferibed by Count Marfigli, Triumfetti, and others, and called the ramofe .or branched orange. This is very much of the nature of the former ; but inftead of confifting of one round globule, it is formed of feveral oblong ones all joined together, and repre- fenting the branches of fome of the fucufes, only they are fliorter; and thefe are all hollow and full of water, ' in the fame manner as the fingle globes of the com¬ mon kind. This has, by way of root, certain fine- and flender filaments, which faften it to the ftones or ftiells near which it is produced ; and it is of a dulky greenilh colour on the furface, and of a fine bluiih green within. The furface, viewed by the microfcope, appears rough, as in the other, and the glandules are of the fame kind, and are always found full of clear water. ORATION, in Rhetoric, a fpeech or harangue, compofed according to the rules of oratory, but fpoken in public. Orations may be reduced to three kinds, viz. the demonftrative, deliberative, and judicial. To the demonftrative kind belong panegyrics, genethliaca, epithalamia, congratulations, &c. To the deliberative kind belong perfuafion, exhortation, &c. And to the judicial, kind belong accufation,. confutation, &c. Funeral ORA [ 301 ] O R . A Oration, Funeral ORATION. See FUNERAL Oration. Orator. ORATOR, among the Romans, differed from a -'■'V"—”'patronus: The latter was allowed only to plead caufes on behalf of his clients } whereas the former might quit the forum and afcend the roftra or tribunal, to harangue the fenate or the people. The orators had rarely a profound knowledge of the law, but they ■were eloquent, and their ilyle was generally correct and concife. They were employed in caufes of im¬ portance, inftead of the common patrons. Orators in the violence of elocution ufed all the warmth of gefture, and even walked back-wards and forwards with great heat and emotion. This it was which occafion- ed a witticifm of Flavius Virginius, who afked one of thofe walking orators, ^uot millia pajjuum declamdjfet? “ How many MILES he had declaimed ?” Similar to the Roman orators were the Grecian Rhetores. See Rhetores. Public ORATOR, an office of very confiderable dig¬ nity, and of fome emolument, in the Englifh univerfi- ties. The public orator is the principal, and in many cafes the only oflenfible, agent for the univerfity, in all thofe matters or forms which are merely external. He carries on or fuperintends all correfpondences which are calcu¬ lated to promote the dignity, or raife the utility, of the feminary which conftitutes him. He has little to do, indeed, with the internal government of the body, for which a variety of officers in different departments are appointed •, but in all public affairs he is, as it were, the mouth of the whole 5 puttihg their deliberations into proper form, and communicating or publithing them, according to the intention of the univerfity. Thus, if the whole univerfity, or a committee appoint¬ ed by them, or by ftatute, or by the will of any parti- eular benefaftor, have, after a comparative trial, ad¬ judged a prize to any perfon or perfons, it is the bufi- nefs of the public orator to inform the fuccefsful parties of the iffue of the trial. Again, If for fingular learn¬ ing, or for any remarkable good will Ihown to the uni¬ verfity by any perfon or perfons, the fenate or convocation are pleafed to declare their grateful fenfe of it either by conferring degrees, or otherwife, as they think fit, the public orator is to notify this intention to the perfon or perfons concerned ", and fo in other cafes. Another part of the public orator’s bufinefs is to prefent young noblemen, or thofe who take honorary degrees, tanqiuim nobiles, to the vice chancellor 5 this Orator, he does in a Latin fpeech, which, according to cir- , Qratur^ cumftances, is either ffiort or long ", and of which the fubjedt is generally a defence of that particular ftatute which allows the fons of noblemen, and fome few others, to proceed to degrees before what is called theJlatuta- ble time* In doing this, encomiums, often ftronger than juft, are made upon the learning and virtue of the no¬ ble candidate ; a view is taken of the dignity of his an¬ cient houfe j the honour is mentioned which has accru¬ ed to the univerfity from the acceflion of fuch a mem¬ ber ; and the oration concludes with promifing great credit from his future condudl, as well as benefit from the influence of his rank in the ftate. Thefe circum- ftances are deemed fufficient grounds for exempting the fons of noblemen from that tedious courfe of ftudy, through which the duller fons of commoners muft all pafs before they be thought worthy of academical honours. ORATORIO, in the Italian mulic, a fort of facred drama of dialogues j containing recitatives, duettos, trios, ritornelh>, chorufes, &c. The fubjefts of thofe pieces are ufually taken from Scripture, or the life of fome faint, &c. The mufic for the oratorios ftiould be in the fineft tafte and beft chofen ftrains. Thefe ora¬ torios are greatly ufed at Rome in the time of Lent, and of late in England. Meneftrier attributes the origin of oratorios to the crufades, and fays that the pilgrims returning from Je- rufalem and the Holy Land, &c. compofed fongs recit¬ ing the life and death of the Son of God, and the myfte- ries of the Chriftian faith, and celebrating the achieve¬ ments and conftancy of faints and martyrs. Others, with more probability, obferve, that the oratorio was an avowed imitation of the opera, with only this differ¬ ence, that the foundation of it was always fome religi¬ ous or at leaft fome moral fubject. Crefcimbeni aferibes its origin to San Filippo Neri, who was born at Flo¬ rence in 1515, and who, in his chapel after fermons, and other devotions, in order to allure young people to pi¬ ous offices, had hymns, pfalms, and fuch like prayers, fung by one or more voices. Among the Ipiritual fongs were dialogues } and thefe entertainments becom¬ ing more frequent, and improving every year, were the occafion that in the feventeeth century oratorios were firft inyented, fo called from the place of their origim „ See H(\whins')s Hijlory of Mujic, ORATORY; THE ART OF SPEAKING WELL UPON ANY SUBJECT, IN ORDER TO PERStJADE. INTRODUCTION. § I. Of the Rife and Progrefs of Oratory. 1 T1'e