EDITED BY 
 
 DIONYSIUS LARDNEE, D.C.L., 
 
 Formerly Professor of Natural Philosopliy and Astronomy in University College, London. 
 
 ILLUSTEATED BY ENGRAVINGS ON WOOD. 
 
 VOL. IX. 
 
 LONDON : 
 WALTON A^B MABEELY, 
 
 UPPER GOWER STREET, AND IVY LANE, PATERNOSTER ROW. 
 1859. 
 
 [The right of Translation is reserved. ] 
 
LONDON : 
 
 BP.ADBDRY, EVANS, AND CO., PRINTERS, WHITEFRIARS. 
 
CONTENTS. 
 
 THE MICROSCOPE. 
 
 PAGS 
 
 Chap. I. — 1. Origin of the term. — 2. Simple microscopes are mag- 
 nifying glasses. — 3. Compound microscope. — 4. Object-glass and 
 eye-glass, — 5. General description of tlie instrument. — 6. Uses 
 of the field-glass. — 7. Reflecting microscopes. — 8. Conditions of 
 distinct vision in the microscope. — 9. Effects of different mag 
 nifying powers. — 10. Distinctness of delineation necessary. — 11. 
 Hence aberration must be effaced. — 12. Achromatic object- 
 lenses. — 13. Sufficient illumination necessary. — 14. Effects of 
 angular aperture. — 15. Experiments of Dr. G oring. — 16. Method 
 of determining the angular aperture, — 17. Mutual chromatic and 
 spherical correction of the lenses 1 
 
 Chap. II, — Mutual chromatic and spherical correction of the lenses 
 (continued), — 18. Centering. — 19. Compound object-pieces. — 20. 
 The eye-piece. — 21. Various magnifying powers adapted to the 
 same microscope. — 22. Actual dimensions of the field of view. — 23. 
 Means of moving and illuminating the object. — 24. Focussing. — 
 25. Preparation of the object. — 26. General description of the 
 structure of a microscope. — 27. The stage. — 28. The illuminators. 
 — 29. The diaphragms 17 
 
 Chap. Ill, — 30, Oblique plane reflectors. The support and move- 
 ment or THE OBJECT : 31, The stage. — 32, Mechanism for focus- 
 sing, — 33. Coarse adjustment. — 34. Fine adjustment. — 35. 
 Method of determining the relief of an object. — 36. Difficulty of 
 bringing the object into the field, — 37. Mechanism for that 
 purpose, — 38. Mechanism to make the object revolve, — 39. 
 Object to be successively viewed by increasing powers. — 40. 
 Slides to be cleaned.— 41. Compressor, — 42. Apparatus for apply- 
 ing voltaic current. The illumination op objects : 43. Curious 
 effects of light on objects. — 44. Illumination by transmission 
 and reflection, — 45. Microscopic objects generally translucent, or 
 maybe made so. — 46. Effects of varying thickness. — 47. Varying 
 
iv 
 
 CONTENTS. 
 
 effects of light and shade, — 48. Uses of the Lieberkuhn. — 49. 
 Eifects of diffraction and interference. — 50. Use of daylight. — 
 51. Artificial light. — 52. Protection of the eye. — 53. Pritchard's 
 analysis of the effects of illumination. . , . . . • 33 
 
 Chap. IV. — Pritchard's analysis of the effects of illumination (con- 
 tinued). Measurement of objects : 54. Measurement distinct 
 from magnifying power. — 55. Measurement by comparison with 
 a known object. — 56. Micrometric scales. — 57. Thin glass 
 plates. — 58. Micrometers. — 59. Le Baillifs micrometer. — 60. 
 Jackson's micrometer. — 61. Measurement by the camera lucida. 
 — 62. Groniometers. Magnifying Power : 63. This term much 
 misunderstood. — 64. Its exact meaning. — 65. Least distance of 
 distinct vision. — 66. Visual estimate of angular magnitude. — 
 67. Method of determining magaifying power by the camera 
 lucida. — 68. Dimensions of the least object which a given power 
 can render visible 49 
 
 Chap. V. — Micropolariscope : 69. Polarisation. — 70. Condition of 
 a polarised ray. — 71. Polarisation by double refracting crystals. 
 — 72. Their effect upon rays of light. — 73. The micropolariscope. 
 The mounting of microscopes: 74. Conditions of efficient mount- 
 ing. — 75. Frauenhoffer's mounting. — 76. Methods of varying the 
 direction of the body. Chevalier's universal microscope : 77. 
 Mounting of this instrument. — 78. Method of rendering it vorti- 
 cal. — 79. Method of adapting it to the view of chemical pheno- 
 mena. — 80. Method of condensing the light upon the object. — 
 Boss's Improved microscope : 81. Useful labours of Mr. Ross. 
 — 82. Details of his improved microscope . . . .65 
 
 Chap. VI. — 83. His object-glasses. Messrs. Smith and Beck's 
 microscope : 84. Their largest and most efficient instrument. — 
 85. Their smaller microscope. — 86. Their object-glasses. — 87. 
 Varley's microscope. M. Nachet's microscope : 88. Their 
 adaptation to medical and chemical purposes. — 89. Multiple 
 microscopes. — 90. Double microscope. — 91. Binocular micro- 
 scope. — 92. Tiiple and quadruple microscopes . . . .81 
 
 THE WHITE ANTS ; THEIR MANNERS AND HABITS. 
 
 Chap. I. — 1. Their classification. — 2. Their mischievous habits. — 
 3. The constitution of their societies. — 4. Chiefly confined to the 
 tropics. — 5. Figures of the king and queen. — 6. Of the workers 
 and soldiers. — 7. Treatment of the king and queen. — 8. Habits 
 of the workers. — 9. Of the soldiers.— 10. The nymphs. — 11. 
 Physiological characters. — 12. First establishment of a colony. 
 — 13. Their use as food and medicine. — 14. The election of 
 the king and queen. — 15. Their subsequent treatment. — 16. 
 The impregnation of the queen. — 17. Figure of the pregnant 
 queen. — 18. Her vast fertility. — 19. Care bestowed upou her 
 eggs by the workers. — 20. The royal body-guard. — 21. The 
 habitation of the colony. — 22. Process of its construction. — 23. 
 
CONTENTS. 
 
 Its chambers, corridors, and approaches. — 24. Vertical section, 
 showing its internal arrangement. — 25. View of these habitations. 
 — 26. Contrivances in their construction. — 27. Use made of 
 them by the wild cattle. — 28. Used to obtain views to seaward. 
 — 29. Use of domic summit for the preservation of the colony. — 
 
 30. Position, form, and arrangement of the royal chamber — its 
 gradual enlargement for the accommodation of the sovereigns. — 
 
 31. Its doors, — 32. The surrounding antechambers and corridors. 
 — 33. The nurseries. — 34. Their walls and partitions. — 35. 
 Their position varied according to the exigencies of the colony. — 
 36. The continual repair and alterations of the habitation. — 37. 
 Peculiar mould which coats the walls. — 38. The store-rooms for 
 provisions — the inclined paths which approach them — the curious 
 gothic arches which surmount the apartments. — 39. The sub- 
 terranean passages, galleries, and tunnels. — 40. The covered 
 ways by which the habitation is approached. — 41. The gradients 
 or slopes which regulate these covered ways. — 42. The bridges 
 by which they pass from one part of the habitation to another. 
 — 43. Eeflections on these wonderful works. — 44. The tenderness 
 of their bodies renders covered ways necessary. — 45. When forced 
 to travel above ground they make a covered way — if it be acci- 
 dentally destroyed they will reconstruct it . . . .97 
 
 Chap. II.— 46. Turrets built by the Termes mordax and the Termes 
 atrox. — 47. Description of their structure. — 48. Their king, 
 queen, worker, and soldier. — 49. Internal structure of their 
 habitation. — 50. Nests of the Termes arborum. — 51. Process of 
 their construction. — 52. Hill nests on the Savannahs. — 53. The 
 Termes lucifugus — the organisation of their societies. — 54. 
 Habits of the workers and soldiers — the materials they use &r 
 building. — 55. Their construction of tunnels. — 56. Nests of the 
 Termes arborum in the roofs of houses. — 57. Destructive habits 
 of the Termes bellicosus in excavating all species of wood-work — 
 entire houses destroyed by them. — 58. Curious process by which 
 they fill with mortar the excavations which they make — de- 
 struction of Mr. Smeathman's microscope. — 59. Destruction of 
 shelves and wainscoting.— 60. Their artful process to escape 
 observation. — 61. Anecdotes of them by Koempfer and Humboldt. 
 — 62. Destruction of the Governor's house at Calcutta — destruction 
 by them of a British ship of the line. — 63. Their manner of 
 attacking timber in the open air — their wonderful power of 
 destroying fallen timber. — 64. The extraordinary behaviour of 
 the soldiers when a nest is attacked 113 
 
 THE SUEFACE OF THE EAPtTH, 
 
 OR FIRST KOTIONS OF GEOGEAPHT. 
 
 Chap. I. — The Surface of the Earth : 1. Origin of the name. — 
 2. Preliminary knowledge. — 3. The distribution of land and 
 watex'. — 4. The undulations of the terrestrial surface. — 5. Geo- 
 graphical Terms : 6. Islands. — 7. Continents. — 8. Peninsu- 
 las. — 9. Isthmuses. — 10. Promontories. — il. Capes and head- 
 
vi 
 
 CONTENTS. 
 
 lands. — 12. The relief of tlie land. — 13. Plains and lowlands. — 
 14. Plateaux and table-lands. — 15. Hills. — 16. Mountains. — 
 17. Systems or chains of mountains. — 18. Oceans. — 19. Seas. — 
 20. Gulfs.— 21. Bays.— 22. Straits.— 23. Channels.— 24. Roads 
 and roadsteads. — 25. Banks and sand-banks. — 26. Reefs. — 27. 
 Soundings.— 28. Lakes.— 29. Rivers.— 30. The bed of a river. 
 —31. The banks of a river.— 32. Tributaries.— 33. Valleys.— 
 84. Watersheds.— 35. Delta.— 36. Estuaries.— 37. Friths.— 
 The G-reat Eastern Continent : 38. Its extent and limits. — 
 39. Its divisions.— 40. The Mediterranean.— 41. Relief.— 42. 
 Its northern belt. — 43. The southern belt. — 44. Prevailing 
 mountain chains, — 45. Outlines of Europe. — 46. White Sea. — 
 47. Norway and Sweden. — 48. British Isles. — 49. France. — 
 50. Spain and Portugal. — 51. Italy. — 52. Sicily. — 53. Oreece. 
 — 54. Archipelago. — 55. Dardanelles and Bosphorus. — 66. The 
 Black Sea. — 57. Sea of Azof. — 58. The Caspian. — 59. Africa. 
 ■ — 60. Its climatological zones. — 61. The Tell and Sahara. — 62. 
 Valley of the Nile.— 63. The central belt.— 64. The fourth 
 zone. — 65. The southern zone. — 66. The coasts 
 
 Chap. II. — 67. Asia. — 68. Its plateaux. — 69. The eastern plateaux. 
 — 70. Its physical character. — 71. The western table-land. — 
 72. British India : Dekkan plateaux. — 73. Australia. — 74. 
 Australasia. — 75. Polynesia. — 76. British Colony : its territory 
 and physical features, — 77. Its climate. — 78. Vegetable produc- 
 tions. — 79. The indigenous animals. — 80. Minerals : Gold. — 
 
 81. Aboriginal tribes. The Western, or New Continent : 
 
 82. Its extent and form. — 83. Divisions: South America. — 84. 
 Central America. — 85. North America.— -86. Its extent and limits. 
 —^87. Its political divisions. — 88. Gulf of Mexico and Caribbean 
 Sea. — 89. Relation between the coasts of the old and new conti- 
 nents. — 90. The relief. — 91. Chippewayan and Rocky Mountains. 
 — 92. Cordilleras and Andes. — 93. Andes of Patagonia and Chili. 
 — 94. Andes of Bolivia and Peru. — 95. Cordilleras. — 96. Potosi. 
 — 97. Pampas of Patagonia and Buenos Ayres. — 98, Selvas of 
 the Amazon. — 99. Llanos of Orinoco. — 100. Alleghanies. — 101. 
 Eastern plain of North America. — 102. Great valley of the Mis- 
 sissippi. — 103. The Prairies. Outlines op the land : 104. 
 The prevalence of the peninsular form. — 105. The South Ame- 
 rican peninsula. — 106. The North American peninsula. — 107. 
 The West Indian Archipelago. — 108. The peninsula of Florida. 
 — 109. Lower California.— 110. Greenland. — 111. Africa. — 
 112. Australia. — 113. New Zealand. — 114. Similar tendency in 
 smaller regions. — 115. The Spanish peninsula. — 116. The Ita- 
 lian peninsula, — 117. The Hellenic peninsula. — 118. The 
 Crimea. — 119. The Scandinavian peninsula. — 120. European 
 peninsula. — 121. The Indian peninsula. — 122. Further India. 
 — 123. Hemisphere of most land. Rivers : 124, Formation of 
 rivers. — 125. Effect of a single ridge, — 126, Example in the 
 
 'eastern continent, — 127. Example in South America, — 128. 
 Effect of parallel ridges. — 129. Chief tributaries considerable 
 rivers. — 130. Example of Missouri, — 131. Trifling elevation of 
 watershed. — 132. Portage. — 133. Examples of rivers in North 
 
CONTENTS. 
 
 America. — 134. Eastern rivers. — 135. Western rirers. — 136. 
 The Mississippi and its tributaries. — 137. Valley of the Missis- 
 sippi. — 138. Red River, Arkansas, Ohio. — 139. St. Louis. — 
 140. IlUnois 145 
 
 Chap. III. — 141. Source of Mississippi. — 142. Missouri and its * 
 tributaries. — 143. The Amazons. — 144. Its tributaries. — 145. 
 The Orinoco.— 146. The Rio de la Plata.— 147. The river 
 system of Europe. — 148. General plan of the rivers of the -world. 
 CLmATE. — 149. Determines the animal and vegetable kingdoms. 
 150. Its dependence on latitude.— 151. Explained by the varying 
 positions of the earth. — 152. Spring equinox. — 153. Sun vertical 
 at equator. — 154. Oblique at all other points. — 155. Its thermal 
 influence in different latitudes. — 156. Position of the earth on 21st 
 June. — 157. Days longer than nights in northern hemisphere. — 
 
 158. Temperature depends on sun's altitude and length of day. — 
 
 159. Thermal influence greatest on 21st June in northern hemi- 
 sphere. — 160. Position of the earth at autumnal equinox. — 161. 
 Why the longest day is not the hottest. — 162. Why the summer 
 is warmer than the spring. — 163. The Dog-days. — 164. Like 
 phenomena in the southern hemisphere. — 165. Position of the 
 earth on 21st December. — 166. Winter season explained. — 167. 
 Why the shortest day is not the coldest. — 168. The Tropics. — 
 169. The sun can only be vertical within them. — 170. Illustra- 
 tion of the varying position of the earth in the successive months. 
 — 171. The arctic polar circles and the frigid zones. — 172. 
 Diurnal and nocturnal phenomena which characterise them. — 173. 
 The torrid zone. — 174. Sun vertical twice a year in the torrid 
 zone. — 175. Temperate zone 161 
 
 Chap. IV. — 176, Climate, dependent on elevation. — 177. Vegetation 
 of the Himalayas. — 178. Vegetation of the Andes. — 179. Animals 
 of the tropics. — 180. The Himalayas — Animals inhabiting 
 them. — 181. The local character of cKmate. — 182. Heat 
 received from celestial spaces. — 183. Why the temperature 
 of the earth is not indefinitely increased. — 184. Effect of 
 clouds. — 185. Effect of contact of air and earth. — 186. 
 Thermal effects of a uniform surface. — 187. Why this regu- 
 larity does not prevail. Mountains. — 188. Maps and globes 
 in relief. — 189. Johnston's Physical Maps.- — 190. Mountain 
 ranges not uniform. — 191. Spurs. — 192. Relief of the earth's 
 surface.- — 193. Effect of the contemplation of mountain scenery. 
 —194. The Pyrenees.— 195. The Alps.— 196. Average height 
 of continents. — 197. New mountain ranges possible. The 
 OoEAN. 198. Grreatest depth.— 199. Uses of the ocean. — 200. 
 Greneral system of evaporation and condensation. — 201. Climatic 
 effects. — 202. Ocean currents.— 203. xintarctic drift current.— 
 204. Its equatorial course. — 205. Grulf stream. — 206. Course 
 and limits of ocean currents evident. — 207. Ocean rich in animal 
 life. — 208. Moral impressions 177 
 
viii 
 
 CONTENTS. 
 
 SCIENCE AND POETRY. 
 
 PAGE 
 
 1. Optical error in the fable of the Dog and the Shadow. — 2. Expla- 
 nation of the phenomena. — ^^3. Table showing the reflection at 
 difierent obliquities. — 4. EflEect of looking down in still water 
 over the bulwark of a ship or boat. — 5. Effect of the varying dis- 
 tance of the observers. — 6. Experiments with a basin of water. 
 — 7. Explanation of their effects. — 8. Scientific errors in Moore's 
 Irish melody, "Oh, had we some bright little isle." — 9. Demon- 
 stration of the physical impossibility of what the poet supposes. 
 — 10. Allusion in Moore's Irish Melody, *' Thus when the lamp 
 that lighted," explained. — 11. Allusion in Moore's melody. 
 While gazing on the moon's light." — 12. Shakspeare's allusion 
 to the cricket. — 13. Moore's allusion to the glowworm. — 14. 
 Shakspeare on the economy of the bee. — 15. Error of the phrase 
 ** blind as a beetle." — 16. Lines from Campbell's " Pleasures 
 of Hope." — 17. Error of the allusions to the foresight of the ant 
 — Lines from Prior. — 18. Verses from the Proverbs. — 19. Cele- 
 brated description of the war-horse in Job. — 20. Unmeaning 
 language of the translation. — 21. Examination of the true mean- 
 ing of the original Hebrew by Dr. McCaul and Professor Marks. 
 — 22. Interpretation by Gesenius. — 23. By Ewald. — 24. By 
 Schultens. — 25. Correct meaning explained . . . ,193 
 
Fig. 37.— chevalier's universal mtcroscopk. 
 
 THE MICROSCOPE. 
 CHAPTEE I. 
 
 t. Origin of the term. — 2. Simple microscopes are magnifying glasses. — 
 3. Compound microscope. — 4. Object-glass and eye-glass. — 5. General 
 description of the instrument. — 6. Uses of the field-glass. — 7. Keflect- 
 
 Lardner's Museum of Science. e 1 
 
 No. 105. 
 
THE MieilOSCOPE. 
 
 ing microscopes. — 8. Conditions of distinct vision in the microscope. — 
 9. Effects of different magnifying powers. — 10. Distinctness of deline- 
 ation necessary. — 11. Hence aberration must be effaced. — 12. Achro- 
 matic object-lenses. — 13. Sufficient illumination necessary. — 14. 
 Effects of angular aperture. — 15. Experiments of Dr. Goring. — 16. 
 Method of determining^the angular aperture. — 17. Mutual clu-omatia 
 and spherical correction of the lenses. 
 
 1. The microscope is an optical instrmnent by means of which 
 we are enabled to see objects or the parts of objects too minute to 
 be seen distinctly with the naked eye, the name being taken from 
 two Greek words, /niicphy (mikron), a little thing, and <r/co7reV 
 (skopeo), I look at. 
 
 2. In a certain sense, all magnifying-glasses may be regarded as 
 microscopes, but the slightly convex lenses, used by weak-sighted 
 persons, cannot with any propriety be so denominated. The 
 higher magnifying lenses, however, used by watchmakers,, 
 jewellers, miniature painters, and others, may with less impro- 
 priety receive the name ; and the small lenses of short focus and 
 high power described in our Tract on " Magnifying Glasses," 
 especially when they have the form of doublets, and are mounted 
 to serve anatomical purposes, and for microscopic delineations, are 
 generally designated simple microscojjes. Since, however, they 
 differ in no respect in their optical principle from common magni- 
 fiers, we have considered it more convenient to explain them 
 under that head, limiting therefore the subject of the present 
 Tract to those optical combinations which are generally called 
 
 COMPOUND MICROSCOPES. 
 
 3. Such an instrument, in its most simple form, consists of a 
 magnifying lens or combination of lenses, by means of which an 
 enlarged optical image of a minute object is produced, and a 
 magnifying lens, or combination of lenses, by which such image is 
 viewed, as an object would be by a simple microscope. 
 
 4. The former is called the object-glass, or objective, since 
 it is always directed immediately to the object, which is placed 
 very near to it ; and the latter the eye-glass, or eye-piece, inas- 
 much as the eye of the observer is applied to it, to view the 
 magnified image of the object. 
 
 5. Such a combination will be more clearly understood by 
 reference to fig. 1, where o is the object, ll the object-glass, and 
 E E the eye-glass. 
 
 The object-glass, L L, is a lens of very short focal length, and 
 the object o is placed in its axis, a very little beyond its focus. 
 According to what has been explained in our Tract upon " Optical 
 Images," 31 et seq. an image 0 o, of o, will be produced at a dis- 
 tance from the object-glass l l, much greater than the distance of 
 
 n 
 
PRINCIPLE OP THE INSTRUMENT. 
 
 0 from it : this image will be inverted with relation to the object ; 
 its top corresponding with the bottom, and its right with the left 
 side of the object, and vice versa : the linear magnitude of this 
 image will be greater than that of the object, in the proportion of 
 o L to 0 L, and consequently its superficial magnitude will be 
 greater than that of the object, in the proportion of the squares of 
 these lines. 
 
 The image o o, thus formed, may be considered as an object 
 ■viewed by the observer, through the magnifying glass e e, and 
 all that has been explained, relating to the effect of such a lens, in 
 our Tracts on *' Magni'fying Glasses" and " Optical Images," will 
 be applicable in this case. The observer will adjust the eye-glass 
 
 Fig. 1. 
 
 E E, at such a distance from o o, as will enable him to see the 
 image most distinctly, and the impression produced upon his sense 
 of vision will be that the image he looks at, is at that distance 
 from his eye, at which he would see such an object most dis- 
 tinctly without the interposition of any magnifying lens; let 
 this distance be that of a similar image o' o', and the impression 
 will be that the object he beholds has the magnitude o' o'. 
 
 The distance of most distinct vision with the naked eye, and 
 the distance from the image at which the eye-glass must be 
 placed to produce distinct vision, both vary for different eyes, but 
 they vary almost exactly in the same proportion, so that the 
 magnifying effect of the eye-glass upon the image o o, will be the 
 same, whether the observer be long-sighted or short-sighted ; in 
 estimating the magnifying power, therefore, of such a combina- 
 tion, we may consider, in all cases, the distance of the eye-^lass 
 E E from the image o o, to be equal to its focal length, and the 
 distance of C o' from the eye-glass, to be 10 inches. (See 
 " Magnifying Glasses/' 8.) 
 
 To estimate the entire amplifying effect of such a microscope, we 
 have only to multiply the magnifying power of the object-^lass 
 by that of the eye-glass ; thus, for exam.ple, if the distance of the 
 image o o from the object-glass be 10 times as great as the 
 
 B 2 3 
 
THE MICROSCOPE. 
 
 distance of tlie object from it, the linear dimensions of the image 
 0 0 will be 10 times greater than those of the object ; and if the 
 focal length of the eye-glass be -| an inch, the distance of most 
 distinct vision being 10 inches, the linear dimensions of o' o' will 
 be 20 times those of o o, and therefore 200 times those of the 
 object ; the linear magnifying power would in that case be 200, 
 and consequently the superficial magnifying power 40000. 
 
 It would seem therefore, theoretically, that there would be no 
 limit to the magnifying power of such a combination ; practically, 
 however, there are circumstances which do impose a limit upon it. 
 It must be remembered that the object must always be placed at 
 a distance from the object-glass, greater than the focal length 
 of the latter, the magnifying power of the object-glass depend- 
 ing on the number of times this distance is multiplied, to make up 
 the distance of the image o o from l l ; if a very great magnifying 
 power be required, the latter distance must be a proportionally 
 great multiple of the former, and as the eye-glass must be farther 
 from the object-glass than the image, the instrument might be 
 increased to unmanageable dimensions. 
 
 There is therefore a practical limit to the increase of the ampli- 
 fying power of the instrument by the increase of the distance of 
 the image o o from the object-glass, and consequently it can only 
 be augmented by the decrease of the focal length of the object- 
 glass, combined with a corresponding decrease of that of the eye- 
 glass. By such means, the distance of o from L L will be con- 
 tained a great number of times in o L, while the latter has not 
 objectionable length, and the distance of the eye-glass from the 
 image o o will be contained a great number of times in the 
 distance of most distinct vision. 
 
 The eye and object glasses are usually mounted at the distance 
 of 10 or 12 inches asunder, adjustments nevertheless being pro- 
 vided, by which their mutual distance can be varied within 
 certain limits. 
 
 6. A convex lens is generally interposed between the object- 
 glass and eye-glass, which receiving the rays diverging from the 
 former, before they form an image, has the effect of contracting 
 the dimensions of the image, and at the same time increasing its 
 brightness. The effect of such an intermediate lens will be 
 understood by reference to fig. 2, where p f is the intermediate 
 lens. If this lens f f were not interposed, the object-glass l l 
 would form an image of the object o at o o ; but this image being 
 too large to be seen at once with any eye-glass, a certain portion 
 of its central part would only be visible. The lens r F, however, 
 receiving the rays before they arrive at the image 0 o, gives them 
 increased convergence, and causes them to produce a smaller 
 4 
 
FIELD-LENS. 
 
 image o' o', at a less distance from the object-glass l l. The 
 dimensions of this image are so small, that every part of it can be 
 seen at once with the eye-glass. 
 
 ' The portion of the image which can be seen at once with the 
 eye-glass, is called the field of yiew of the microscope. 
 
 It is evident from what has been stated, that the effect of the 
 
 Fig. 2. 
 
 0 
 
 0 
 
 lens F p is to increase the field of view, since by its means the 
 entire image of the object can be seen, while without its inter- 
 position the central parts only would be visible. 
 
 The lens F F has, from this circumstance, been called the 
 
 FIELD -LENS. 
 
 But the increase of the field is not the only effect of this 
 arrangement. 
 
 The light which would have been diffused over the surface of 
 the larger image o o, is now collected upon that of the smaller 
 image o' o' ; and the brightness, therefore, will be increased in the 
 same proportion as the surface of o o is greater than the surface of 
 0' o', that is, in the proportion of the square of o o to the square 
 of 0' o'. 
 
 Another effect of the field-lens is to diminish the length of the 
 microscope, for the eye-glass, instead of being placed at its focal 
 distance from o o, is now placed at the same distance from o' o'. 
 
 7. In this brief exposition of the general principle of the micro- 
 scope, the image, which is the immediate subject of observation, 
 is supposed to be produced by a convex lens ; such an image, 
 however, may also be produced by a concave reflector, and being 
 so produced may be viewed with an eye-glass, exactly in the same 
 manner as when produced by a convex lens. 
 
 Microscopes have accordingly been constructed upon this 
 principle, and are distinguished as eeflectikg microscopes ; 
 those in which the image is produced by a lens being called 
 
 KEFBACTING MICROSCOPES. 
 
 The principle of a reflecting microscope will be understood by 
 reference to fig. 3, where l l is the concave reflector, of which c 
 is the centre ; the object o is placed towards the reflector, at a 
 
 5 
 
THE MICROSCOPE. 
 
 distance from c greater than half the radius, and an inverted 
 image of it is formed at o o, which, as in the case of the refracting 
 microscope, is looked at with an eye-glass e e. 
 
 The great improvements which have taken place within the last 
 twenty years in the formation of the object-glasses of refracting 
 microscopes, have rendered these so very superior to reflecting 
 
 Fig. 3. 
 
 
 
 T 
 
 
 
 
 E ( 
 
 
 
 0' 
 
 microscopes, that the latter class of instruments having fallen so 
 completely into disuse, it will not be necessary here to notice 
 them further. 
 
 In what has been explained, the general principle only of the 
 microscope has been developed ; many important circumstances of 
 detail upon which its efficiency mainly depends must now be 
 noticed. 
 
 8. The conditions which render the vision of an object with the 
 microscope clear and distinct are essentially the same as those 
 which determine the clearness and distinctness of our perception 
 of an object with the naked eye. It will be found, by reference 
 to our Tract upon the Eye," that these conditions are three : — 
 
 1. That the visual angle should be sufficiently large; 
 
 2. That the outlines and lineaments of the object should be 
 sufficiently distinct ; and 
 
 3. That the object shoidd be sufficiently illuminated. 
 
 It is evident that if any one of these conditions fail to be ful- 
 filled, our visual perception of the object will be defective* If 
 the object, for example, be exceedingly minute, though it be 
 perfectly delineated and strongly illuminated, it will be either 
 altogether invisible, or will appear as a mere speck. 
 
 If its outlines and lineaments be ill-defined, as when a tree or 
 other object is seen through a mist, our perception of it will also 
 be defective ; and in fine, though it have sufficient magnitude and 
 be perfectly delineated, we may fail to see it distinctly for want 
 of sufficient light upon it, as when we look at objects towards the 
 dose of twilight. 
 
CONDITIOK^S G^" EFFICIENCY. 
 
 The object which is submitted to our sense of vision with the 
 jaicroscope, being the optical image produced by the object-glass, 
 our perception of it can only be dear and distinct, provided the 
 three conditions above stated are fulfilled, that is, provided it be 
 viewed under a sufficient visual angle, that its outline and 
 lineaments be shown with perfect distinctness, and that it be 
 •sufficiently illuminated. 
 
 The conditions, therefore, upon which the efficisncy of the 
 microscope must depend will necessarily be those which will 
 confer upon the image, submitted to the observer, the qualities 
 ; above stated. 
 
 The optical conditions which determine the visual angle or 
 apparent magnitude of the image, as viewed with the eye-glass, 
 have been already explained ; and it is evident that these con- 
 ditions can always be fulfilled, provided object-glasses and eye- 
 glasses of sufficiently short focus can be produced. Speaking 
 generally, the magnifying power of the object-glass will be limited 
 by the proportion which the length of the microscope will bear to 
 its focal length ; and the magnifying power of the eye-giass will 
 he limited only by its power of approaching sufficiently close to 
 the image, without too much contracting the field of view. 
 
 If the purpose of the observer were merely to see the object as 
 a whole, so as to obtain a perfectly accurate notion of its outlines, 
 a moderate magnifying power would, in general, suffice. But in 
 most microscopic researches it is desired to ascertain, not merely 
 the general outlines of the object, but the far more minute linea- 
 ments of its structure ; and to render these visible in the minuter 
 class of objects, amplifying powers of a very high order are 
 indispensable. 
 
 9. The powers, indeed, which exhibit to the observer the 
 general outline of an object, are rarely sufficient to show the 
 minute lineaments of its structure. To perceive the general 
 outline, it is necessary that the entire object should be included 
 at once within the field of view, and this could not be the case, 
 if the magnifying power exceeded a moderate limit. The power, 
 on the other hand, which is sufficiently great to show the most 
 minute parts of the structure, would necessarily be so great that 
 ^ very small part only of the entire object would be comprised in 
 the field of view. 
 
 From these circumstances it will be readily understood, that 
 each class of powers have their j)eculiar uses, neither superseding 
 the other ; when we desire to observe the general form of a micro- 
 scopic object, we must view it with a low power. When we 
 desire, on the other hand, to examine its parts, and if, for example, 
 it be an animalcule, to observe it member by member, and organ 
 
THE MICKOSCOPE. 
 
 by organ, we must call to our aid the higher class of power. In 
 fine, a complete microscopic analysis of an individual object will 
 require that it should be viewed successively with a series of 
 gradually increasing powers. 
 
 10. But magnifying powers, to whatever extent they may be 
 carried, will be of no avail if the image produced by the object-glass 
 be not perfectly distinct and well defined ; and it wiU be evident 
 upon the slightest consideration, that any minute imperfections 
 which may exist in its delineation, will be rendered more and 
 more glaring and intolerable, the higher the magnifying power 
 under which it is viewed. 
 
 With a common magnifying glass, or simple microscope, we 
 view the object itself, and are subject to no other optical imper- 
 fections in our perception of it, than such as may arise from the 
 imperfection of the lenses through which we view it ; and since 
 with such instruments the magnifying power can never be con- 
 siderable, small defects of delineation are never perceptible. It is 
 quite otherwise, however, with the class of instruments now under 
 consideration, where magnifying powers, from 1000 to 2000 of the 
 linear dimensions, are often brought into play. 
 
 These circumstances render it indispensable that the image of 
 the object produced by the object-glass, and viewed through the 
 eye-glass, should have the utmost attainable distinctness of de- 
 lineation ; not only as regards its outline, but also as respects the 
 most minute details of its structure and colouring. 
 
 11. Now the solution of this problem, presented to scientific and 
 practical men the most enormous difl&culties ; difficulties so great 
 as to have been regarded, by some of the highest scientific autho- 
 rities of the last half-century, as absolutely insurmountable. 
 Happily, nevertheless, the problem has been solved ; and without 
 disparagement to the great lights of science, we must admit that 
 its solution has been mainly the work of practical opticians. It 
 is true that the general principles upon which the form and 
 material of the lenses depend, were the result of profound mathe- 
 matical research, but these principles were established and well 
 understood at the moment when the practical solution of the pro- 
 blem was, by scientific authorities themselves, pronounced to be 
 all but impossible. Opticians, stimulated by microscopists and 
 amateurs, then applied themselves to the work, and by a long 
 series of laborious and costly trials, attended with many and 
 most discouraging failures, at length arrived at the production 
 of optical combinations, which have rendered the microscope one 
 of the most perfect instruments of philosophic research, and one, 
 to the increasing powers of which, we can scarcely see how any 
 limit can be assigned. 
 
 8 
 
ABERRATIONS EFFACED. 
 
 To appreciate the circumstances whicli these great difficultiefe 
 have consisted, it will be necessary that the reader should revert 
 to our Tract upon " Optical Images," 39 et seq. It is there shown, 
 that when an object is placed before a convex lens, the image of it 
 which is produced, is not in any ease a faithful copy of the object. 
 In the first place, each portion of the lens, proceeding from its 
 centre to its borders, produces a separate image ; this series of 
 images, being ranged at different distances from the lens : when 
 these images are looked at, as they would be, for example, with 
 the eye-glass of the microscope, they are seen projected one upon 
 another, and being slightly different in their magnitudes, a con- 
 fusion of outline and lineaments ensues, so that the object appears 
 as though it were viewed through a mist. 
 
 This sort of indistinctness, called spherical aberration^ has been 
 fully explained in our Tract upon " Optical Images," and the 
 general principles, by which its effects may be more or less miti- 
 gated, have been there explained. 
 
 It has been in the diminution, if not entire extinction, of this 
 cause of indistinctness, by the happy adaptation of the curvatures 
 of the lenticular surfaces entering into the optical combinations 
 which form the microscope, that the address and genius of the 
 practical opticians has been chiefly manifested ; and if it cannot 
 be stated, with strict truth, that all the effects of spherical aber- 
 ration have been effaced in the best instruments now placed at 
 the disposition of the observer, it may, at all events, be safely 
 af&rmed, that they exist in so small a degree as to offer no serious 
 impediment to his researches. 
 
 But independently of this source of indistinctness, there is 
 another which has also been fuUy explained in our Tract upon 
 " Optical Images," 39. 
 
 Light is a compound principle, consisting of several elements, 
 differing in colour and also in refrangibility, the consequence of 
 which is, that when an object is placed before a convex lens, it 
 is not one image which is formed of it, but a series of images, 
 varying in colour, from a violet or blue, through all the tints of 
 the rainbow, to a red ; these images are placed at slightly dif- 
 ferent distances from the lens, and when viewed through the eye- 
 glass, would be projected one upon the other, and being of slightly 
 different magnitudes, the consequence of such projection would 
 be, that their outlines, and those of all their parts, would be 
 more or less fringed with iridescent colours, an effect which, 
 it is needless to say, would destroy the distinctness of the 
 lineaments. 
 
 12. The principle upon which this chromatic aberration is 
 counteracted, has been fully explained in our Tract upon "Optical 
 
 9 
 
THE MICROSCOPE. 
 
 Images." It follows from what is there stated, that all confusion 
 produced by this cause, can be removed by substituting for simple 
 convex lenses, compound ones, consisting of a 
 double convex lens of crown-glass c c', fig. 4, 
 cemented to a plano-concave lens of flint glass. 
 
 The image produced by such a combination, 
 will be distinct and free from colour, provided 
 that certain conditions be observed in the curva- 
 tures given to its component lenses. 
 
 13. Assuming then, that by such combinations 
 the image presented to the eye-glass is a faith- 
 ful reproduction of the object, in its proper colours, 
 perfectly distinct in all its lineaments, and suf- 
 ficiently amplified, there is still one remaining 
 condition for distinct vision, which is, that this 
 image should be sufficiently bright. It will, 
 therefore, be necessary here, to examine the con- 
 ditions on which its brightness, or illumination, 
 depends. 
 
 In the first place it is very evident that, other things being the 
 same, the illumination of the image Avill be proportionate to that 
 of the object, and in the inverse proportion of its superficial 
 amplification ; for the light which is transmitted from the object, 
 being diflfused over the surface of the image, will be necessarily 
 more feeble as the superficial magnitude of the image is greater. 
 The higher the magnifying power used, therefore, the greater is 
 the necessity that the object should be intensely illuminated. 
 
 But the brightness of the image depends not only on the in- 
 tensity of the illumination of the object, but also on the proportion 
 of the light emanating from each point of the object, which arrives 
 at the corresponding point of the image ; and this, as we shall now 
 show, will depend conjointly on the linear opening, or available 
 diameter of the object-glass, and the distance of the object from it. 
 
 To make this more plain, let o o', fig. 5, be the object, and L l' 
 the object-glass. We are to consider that each point of the object 
 is a centre, from which rays emanate towards 
 ^^s- 5. the object-glass ; thus, for example, rays 
 
 issuing from the point c, form a cone, of which 
 the object-glass is the base, and of which c is 
 the vertex ; supposing all these rays to pass 
 through the object-glass, and to be refracted 
 by it, they will converge to the point of the 
 image which corresponds to c. 
 
 In the same manner, the rays which diverge 
 from any other point, such as o, likewise form a cone, of which 
 10 
 
 Fig. 4. 
 
ANGULAR APERTURE. 
 
 that point is the vertex, and the object-glass the base, and after 
 passing* through the lens, they will converge to the corresponding 
 point of the object. 
 
 Thus it appears that each point of the image is illuminated by 
 as many rays as ai-e included within such a cone as we have here 
 described ; that is to say, one whose base is the object-glass, and 
 whose vertex is on the object. But it is evident that the number 
 of rays included in such a cone, depends exclusively upon the 
 magnitude of its angle, that is the angle L c L', formed by lines 
 drawn from a point, c, upon the object. 
 
 14. This angle, which forms, therefore, an element of capital 
 
 Fig. 6. Pig. 7. 
 
 importance in the estimation of the efficiency of the microscope, is 
 called the angulae apeettjee of the object-glass. 
 
 The effect produced by the variation of the angular aperture of 
 the object-glass, other things being the same, will be rendered 
 
 11 
 
THE MICEOSCOPE. 
 
 still more clearly intelligible by reference to figs. 6 and 7, where 
 two lenses, l l and l' l', having equal focal lengths, are repre- 
 sented ; the same object, o ando', is placed 
 at the same distances from them, and equal 
 images of it, 1 1 and i' i', are produced at 
 equal distances from the lenses. The 
 angular aperture of l l, being l o l, is 
 greater than that of l' l', which is l' o' l' ; 
 and it is evident that a greater number of 
 rays issuing from the object, will fall upon 
 the lens l l, than upon l' l', in the 
 proportion of the square of the angular 
 aperture of the former to that of the latter ; 
 tlius, if the angular aperture of l L be 
 tmce that of l' l', the number of rays 
 which fall on L L will be four times the 
 number which fall on tJ l'. 
 
 Supposing, then, that all the rays which 
 fall upon each of the lenses, pass through 
 them, and are made to converge upon corre- 
 sponding points of the images 1 1 and l' i', 
 it is clear that each point of the image 1 1 
 will be more intensely illuminated than the 
 corresponding point of i' i', in the propor- 
 tion of the square of the angular aperture 
 of L L to that of l' L' ; and if these apertures 
 be in the proportion above supposed of two 
 to one, the several points of the image 1 1 
 will be four times more intensely illumi- 
 nated than those of i' i'. 
 
 15. As a practical example of the effect 
 of the angular aperture upon the image, 
 we here give seven drawings made by the 
 late Dr. Goring, of the appearance of a 
 particle of dust, or a scale, as it is called, 
 of a butterfly's wing, viewed with the same 
 magnifying power, the angular aperture of 
 the lens being successively augmented. 
 When the aperture was reduced to the 
 smallest limit, the object appeared as re- 
 presented at A, fig. 8 ; when the aperture 
 was increased in the proportion of 2 to 3, 
 the object assumed the appearance repre- 
 sented at B, and, in short, by successively increasing the aperture, 
 it assumed the appearances shown in c, D, E, r, and g. It ^\ ill be 
 12 
 
ANGULAR APERTURE, 
 
 evident, therefore, tliat by the mere effect of tins increased illumi- 
 nation, the lineaments showing the structure of the object, which 
 were altogether imperceptible in c and d, began to be developed 
 but very imperfectly in e, were more visible in r, and becam* 
 quite distinct in g. 
 
 The great and manifest importance, therefore, of the angle of 
 aperture to the efficiency of the microscope, renders it indispen- 
 sable that easy and practicable means should always be attainable 
 for determining it. If the distance of the object from the object- 
 glass, and the virtual opening or diameter of the object-glass 
 could be always exactly measured ; and if all the rays which 
 i'all on the object-glass could be assumed to pass through it, and 
 to converge upon the image, then the angular aperture would be 
 an element of very easy calcidation. But it is not practicable to 
 obtain these data, and it cannot be assumed that all the rays 
 which are incident upon the object-glass will pass through it, 
 and be made to converge upon the image. 
 
 16. Instead, therefore, of calculating the angular aperture in 
 this manner, it is determined by immediate experiment. 
 
 The greatest angle of aperture of which a given lens is capable, 
 ■wiVL be found by determining the greatest obliquity with which 
 it is possible for rays to fall upon the object-glass, so as to be 
 refracted by it to the eye-glass. The following method of ascer- 
 taining this, for any given object-glass, was contrived and 
 practised by Mr. Pritchard, at an early epoch in the pro- 
 gress of the improvement of the microscope, when the importance 
 of the angular aperture was demonstrated by that eminent artist 
 and Dr. Goring. The same method, with but little modification, 
 is that still practised by opticians. 
 
 Let m m, fig. 9, b.e the microscope, the object end being fixed 
 upon a pivot, so that the eye end can be moved over a graduated 
 semicircle. Let a small luminous object, such as the flame 
 of a candle, be placed in the direction r r, at the distance of 6 or 
 8 feet, so that the rays proceeding from it to the object-glass may 
 be considered as parallel. If the microscope be directed towards 
 the candle, all the rays will fall perpendicularly on the object- 
 glass, and will evidently pass through it to the eye-glass. If the 
 microscope be then turned on the pivot to the left, the rays will 
 fall more and more obliquely on the object-glass, and a less and 
 less number of them will p^ass to the eye-glass. 
 
 "When such a position as m m is given to the microscope, those 
 rays only which fall upon the border of the object-glass upon the 
 right of the observer, will arrive at the eye-glass, and the field of 
 view will then appear, as shown at /, half illuminated and half 
 dark. If the microscope be moved beyond this position, the field 
 
 13 
 
THE MICROSCOPE. 
 
 will be entirely dark, no rays being transmitted to the eye- 
 glass. 
 
 If tKe microscope, on the contrary, be moved to the other side 
 of the graduated semicircle, the same appearances will be pro- 
 duced, and when it assumes the position m' m', the field will bo 
 again half illuminated, and beyond that point it will be dark. 
 
 Fig. 9. 
 
 The arc of the graduated semicircle, included between the two 
 j»ositions m m and m' 7n% will then be the measure of the angular 
 aperture of the object-glass, since that arc will correspond with 
 the greatest obliquity, at which rays diverging from the object to 
 14 
 
POSITIVE AND NEGATIVE ABERRATION. 
 
 the object-glass, can pass tlirougli tlie latter, so as to arrive at the- 
 eye-glass. 
 
 Such are then, generally, the means by which the three con- 
 ditions of distinct vision with the microscope will be fulfilled. The 
 second of these conditions, that which involves the complete cor- 
 rection of the chromatic aberration, will, however, require here 
 some further development, since it involves circumstances which 
 have demanded the greatest artistic skill on the part of the 
 makers. 
 
 17. It has been shown in our Tract upon "Optical Images," 53 et 
 seq., that the chromatic aberration of lenses is corrected by combin- 
 ing together two lenses, one of flint and one of crown glass, which 
 have different effects upon the separation of the coloured images, 
 the curvatures of their surfaces being so related, the one to the 
 other, that the separation which would be produced by either is 
 exactly counteracted by an equal separation in a contrary direc- 
 tion by the other. If the curvatures, however, of the two lenses 
 be not so related as to produce this exact compensation, they may 
 either give a predominance to the effect of the one or the other, so 
 as to produce chromatic aberrations of opposite lands ; the coloured 
 images thus produced being ranged in a contrary order. 
 
 When a single convex lens is used, the most refrangible rays 
 are brought to a focus, nearer to the lens than the least refran- 
 gible ; and consequently the violet and blue images are formed 
 nearer to the lens than the red and orange. This is called 
 
 POSITIVE CHEOMATIC ABEEEATIOIT. 
 
 If by combining two lenses of flint and crown glass this aberra- 
 tion be more than compensated, that is, if the blue and violet 
 images are not merely brought to coincide with the red and orange 
 ones, so as to render the lens achromatic, but made to interchange 
 place with them, so that the red and orange shall be nearest to, 
 and the blue and violet farthest from the lens, the chromatic 
 aberration will be i^^egative. 
 
 The importance of this in the practical construction of the 
 microscope will presently appear. 
 
 It must be remembered that the microscope consists of the 
 object-glass, the field-glass, and the eye-glass, and that its 
 efficiency depends not merely upon the fidelity of the image pro- 
 duced by the object-glass, but upon that which is seen by the 
 observer looking through the eye-glass. This last must be an 
 exact reproduction of the object in form and colour. 
 
 Now it is easy to show that if the object-glass be absolutely 
 achromatic, the image seen by the observer through the eye-glass 
 will not be so ; for, in that case, the rays forming the image pro- 
 duced by the object-glass passing successively through the field- 
 
 15 
 
THE MICROSCOPE. 
 
 f glass and the eye-glass, neither of which are achromatic, the 
 image viewed by the observer through the eye-glass must be 
 affected by as much positive aberration as is due to the combiaation 
 of the field-glass and the eye-glass. 
 
 This defect might, it is true, be remedied by making both 
 the field-glass and eye-glass achromatic ; but independently of 
 other objections to such an expedient, it would be needlessly 
 expensive ; and the same purpose is attained in a much more 
 simple manner, upon the principles of positive and negative 
 chromatic aberrations, which have just been explained. 
 
 The method practised for this purpose may be briefly and gene- 
 rally explained thus : The field-glass and the eye-glass being 
 simple convex lenses, produce positive chromatic aberration. The 
 object-glass, on the other hand, being a compound lens, may be 
 so constructed, according to what has been just explained, as to 
 produce negative chromatic aberration. 
 
 16 
 
Fig. 42 —SMITH AND beck's MICROSCOPE. 
 
 THE MICROSCOPE. 
 
 LARDiTfiR's Museum op Scienck. 
 No. 107. 
 
 0 
 
 17 
 
THE MICEOSCOPE. 
 
 CHAPTEE II. 
 
 Mutual chromatic and spherical correction of the lenses (Continued). — 
 18. Centering. — 19. Compound object-pieces. — 20. The eye-piece. 
 — 21. Various magnifying powers adapted to the same microscope. 
 — 22. Actual dimensions of the field of view. — 23. Means of moving 
 and illuminating the object. — 24. Fociissing. — 25. Preparation of the 
 object. — 26. General description of the structure of a microscope. — 
 27. The stage.— 28. The illuminators.— 29. The diaphragms. 
 
 Now let us suppose that the entire combination of lenses is so 
 formed, that the negative chromatic aberration produced by the 
 object-glass shall be exactly equal to the positive chromatic 
 aberration, produced by the field-glass and the eye-glass. In 
 that case, it is evident that the one aberration will extinguish the 
 other, and that the image viewed by the observer through the eye- 
 glass will be an exact reproduction of the object, being exempt 
 from all aberration whatever. 
 
 To make this more evident, Let LL, fig. 10, be the compound 
 object-glass, consisting of a double convex lens of crown glass, 
 and a plano-concave lens of flint-glass, formed so as to produce 
 negative chromatic aberration ; let F r be the field-glassj e e the 
 eye-glass, and o the object. 
 
 Let V V R R be the coloured images of the objects, which would 
 be produced by l l, if f f were not interposed ; these images will 
 be slightly concave towards L L, according to what has been 
 explained in our Tract upon ' * Optical Images," 47 et seq. ; and since 
 L L is supposed to have negative aberration, the red images r e 
 will be nearest to it, and the violet ones, v v, most remote from it. 
 
 But the rays which would converge upon the various points of 
 these images being intercepted by the field-glass f f, are rendered 
 more convergent by it, and the images are accordingly formed 
 nearer to it. This lens, F r, also increases the convergence of the 
 violet rays which are most refrangible, more than it increases that of 
 the red rays which are least refrangible. The consequence of this 
 is, that the violet and red images are brought closer together than 
 they were, as shown in the figure ; but still the violet images are 
 more distant from F F than the red, so that the chromatic aberra- 
 tion of L L and F F conjointly is still negative, though less than 
 the aberration of L L alone. 
 
 There is another effect produced by the lens F F which it is 
 'jnportant to notice. The images produced by L l, which were 
 slightly concave towards f f, are changed in their form, so as to 
 be slightly concave towards e e. The cause of this change has 
 t>eeii already explained in our Tract upon ** Optical Images," 46. 
 
 I 
 
Fig. 10. 
 
THE MICROSCOPE. 
 
 In fine, then, the rays diverging from the images R' u' v' V, 
 after passing through the eye-glass e e, have their divergence 
 diminished, so as to diverge from more distant points, 1 1. The 
 divergence of the violet rays,v' V, being most refrangible, is most 
 diminished, and that of the red rays, b' e', being least refrangible, 
 is least diminished. If their divergence were equally diminished, 
 a series of coloured images would be formed at 1 1, the violet being 
 nearer to, and the red farther from E e ; but the divergence of the 
 violet, which is already greater than the red, is just so much 
 greater than the latter, that the difference of the effects of e e 
 upon it is such as to bring the images together at 1 1. 
 
 Thus it appears, that the positive aberration of the eye-glass 
 E E is exactly equal to the negative aberration of L L and r e taken 
 conjointly, so that the one exactly neutralises the other, all the 
 coloured images coalescing at 1 1, and producing an image alto- 
 gether exempt from chromatic aberration. 
 
 There is another important effect produced by the eye-glass ; 
 the images e' e' v' v', which are slightly concave towards E e, 
 are rendered straiglit and flat at 1 1 ; the principle upon which 
 this change depends has been also explained in our Tract upon 
 ** Optical Images," 46. 
 
 Thus, it appears that, by this masterly combination, a multi- 
 plicity of defects, chromatic, spherical, and distortive, are made, 
 so to speak, to extinguish each other, and to give a result, 
 practically speaking, exempt from all optical imperfection. 
 
 18. There is stQl another source of inaccuracy which, though it 
 is more mechanical than optical, demands a passing notice. All 
 the lenses composing the microscope require to be set in their 
 respective tubes, so that their several axes shall be directed in 
 the same straight line with the greatest mathematical precision. 
 This is what is called centeeing the lenses, and it is a process, 
 in the case of microscopes, which demands the most masterly skill 
 on the part of the workman. The slightest deviation from true 
 centering would cause the images produced by the different lenses 
 to be laterally displaced, one being thrown more or less to the 
 right and the other to the left, or one upwards and the other 
 downwards ; and even though the aberrations should be perfectly 
 effaced, the superposition of such displaced images would effec- 
 tually destroy the efficiency of the instrument. 
 
 19. In what precedes, we have, to simplify the explanation, 
 supposed the object-glass to consist of a single achromatic lens, a 
 circumstance which never takes place except when very low 
 powers are sufficient. A single lens, having a very high magni- 
 fying power, would have so short a focus and such great curvature, 
 that it would be attended with great spherical aberration, inde- 
 
 30 
 
COMPOUND OBJECT-PIECES. 
 
 pendently of otlier objections; 
 obtained by combining several 
 acbromatic lenses in the same 
 object-piece, so that the rays 
 proceeding from the object are 
 successively refracted by each 
 of them, and the image sub- 
 mitted to the eye-glass is the 
 result of the whole. 
 
 The optical effect of such a 
 combination will be more 
 clearly understood by refer- 
 ence to fig. 11, where LL, l'l', 
 and l" l", represent a com- 
 bination of three achromatic 
 object-glasses. Let o o be 
 the object, placed a little 
 within the focus / of the lens 
 L L. The image of o o, pro- 
 duced by L L, would then be 
 an imaginary one in the posi- 
 tion 1 1 ; (see Tract on Optical 
 Images," 35, et seq,). After 
 passing through L L, the rays, 
 therefore, fall upon i/ 1% as if 
 they diverged from the several 
 points of the image 1 1, which 
 may, therefore, be considered 
 as an object placed . before the 
 lens l' l'. Let /' be the focus 
 of L' I.' ; the image of 1 1 pro- 
 duced by l' j/ will therefore be 
 imaginary, and will be at i' i' ; 
 the rays after passing through 
 1/ will fall upon l" l*, as if 
 they diverged from the several 
 points of I' i\ This image i' i', 
 therefore, may be considered 
 as an object placed before the 
 lens l" l". Let/" be the focus 
 of this lens ; the image of i' i' 
 produced by l" l" will then be 
 i" i", and will be real ; this will 
 then, in fact, be the image 
 transmitted to the eye-piece. 
 
 great powers, therefore, have been 
 Fijr. n. 
 
 21 
 
THE MICROSCOPE. 
 
 To render tlie diagram more easy of comprehension, we have 
 not here attempted to represent the several distances in their 
 proper proportions. 
 
 The compound lenses, of which object-pieces consist, are 
 generally, as represented in the figure, plane on the sides presented 
 towards the object. This is attended, among other advantages, 
 with that of allowing a larger angle of aperture than could be 
 obtained if the surface presented to the rays diverging from the 
 object were convex. 
 
 The extreme rays diverging from each point of the object fall 
 upon the surface of the object-glass with a greater and greater 
 obliquity as they approach its borders, and since there is an 
 obliquity so extreme that the chief part of the rays would not 
 enter the glass at all, but would be reflected from it, the angle of 
 aperture must necessarily be confined within such limits, that the 
 rays falling from the borders of the lens will not be so oblique as to 
 come under this condition. If the surface of the object-glass pre- 
 sentedto the object were convex, it is evident that the rays diverging 
 from an object at a given distance from it would fall upon its borders 
 with greater obliquity than if it were plane, and, consequently, 
 such an obj ect-glass would allow of a less angle of aperture than 
 a plano-convex one with its plane side towards the object. 
 
 Improvements have recently been made in object-glasses, by 
 which angles of aperture have been obtained so great, as not to 
 admit even of a plane surface being presented to the diverging 
 pencil, and it has accordingly been found necessary, in such cases, 
 to give the object-glasses the meniscus form (Optical Images, 25), 
 the concave side being presented to the object. By this expedient 
 angles of aperture have been obtained so great as 170^. If the 
 surface of the object-glass presented to the object were plane, the 
 extreme rays of the central pencils, with such an angle of aper- 
 ture, would fall upon the surface of the lens with obliquities of 
 not more than 5°, and the obliquities of the extreme rays of 
 the lateral pencils would be even less. Under such circum- 
 stances, the chief part of the rays near the borders of the 
 lens would be reflected, and, consequently, its virtual would be 
 less than its apparent angle of aperture. It is questioned by some 
 microscopists that even with the expedient of a concave external 
 surface, a practically available angle of aperture so great as 170° 
 can be obtained. 
 
 The three achromatic lenses here described being mounted, so 
 that their axes shall be precisely in the same straight line, con ■ 
 stitute what is generally called an object-glass, but which, 
 perhaps, might with more convenience and propriety be denomi- 
 nated an OBJECT-PIECE. 
 22 
 
COMPOUND OBJECT-PIECES. 
 
 The power of the object-pieces is usually indicated by thr 
 makers, by assigning their focal lengths; but as these object- 
 pieces are composed of several lenses, having different focai 
 lengths, it is necessary to explain what is meant by the focai 
 length of the combination. 
 
 Let L be a single convex lens, and o the compound object-piece; 
 suppose then, the same object placed successively at the same 
 distance from L and 0, and let L have such a convexity that it 
 will produce an image, i, of the object equal to the image i', which 
 the object-piece, o, produces, and that the distance of this image, 
 I, from the single lens l, is equal to the distance of the image I' 
 from the object-piece o. In that case, the single convex lens l, 
 being, in fact, the optical equivalent of the compound object-piece 
 0, its focal length is taken to be that of the object-piece o. Thus, 
 for example, if the lens l, having a focal length of one inch, 
 produce the same image of the same object similarly placed before 
 it, as would the object-piece o, then the focal length of the object- 
 piece 0 is said to be one inch. 
 
 In short, the single lens L, and its equivalent compound object- 
 piece 0, differ only in this, that the images produced by l are 
 defaced more or less by aberration, from which the images pro- 
 duced by 0 are altogether exempt. 
 
 These object-pieces are sold by some makers so fixed that their 
 component lenses are inseparable, the observer being unable to use 
 any one of them as an object-glass without the others; other 
 makers, however, mount them in such a manner that the first and 
 second lenses, l l and V l', may be unscrewed or drawn off, and 
 the lens l" l" alone used as the object-glass; or l' l' may be 
 screwed on, the two lenses l' jJ and l" l" then making an object- 
 piece of greater power ; by this arrangement the observer obtains, 
 without increased expense, three object-pieces of different powers. 
 
 After what has been said, however, of the exact manner in 
 which the aberrations of the field and eye glasses are corrected 
 and balanced by the contrary aberration of the object-piece, it will 
 be easily understood, that the economy by which three powers are 
 thus obtained, is gained at the expense of the efficiency of the 
 instrument; for if the aberrations of the triple object-piece are so 
 adjusted as exactly to balance those of the other lenses, that balance 
 will no longer be maintained when the lens L l; and still less 
 when the lens L' l', is removed. It is on this account that some 
 makers, who are the most scrupulous as to the character of theii 
 instruments, refuse to supply separable object-pieces. 
 
 The imperfection, however, produced in this case by disturbing 
 the balance of the aberrations is of less importance, inasmuch a^ 
 by removing the lens L l, and still more by removing l' l', th<i 
 
 23 
 
THE MICEOSCOPE. 
 
 magnifying power is so considerably diminished, that the defects 
 of the image produced by the unbalanced aberrations are very 
 inconsiderable, and the observer is generally content to tolerate 
 them on account of the great economy gained by the separation of 
 the lenses, which supplies, without additional expense, three- 
 independent object-pieces. 
 
 Some of the foreign makers, less scrupulous in the exact ad- 
 justment of their optical combinations, make all the three lenses 
 composing each triple object-piece exactly similar, unscrewing 
 one from another, so as to enable the observer to use one, two, or 
 three at pleasure. It is evident that, with such combinations, the 
 aberrations can never be so exactly balanced as they are in the 
 object-pieces above described ; but in the instruments to which 
 they are applied, powers exceeding 700 or 800 are almost never 
 attempted, and the aberrations, though imperfectly compensated, 
 are sufficiently so to prevent much injurious confusion in the 
 images. 
 
 In the superior class of instruments, where magnifying power 
 is pushed to so extreme a limit as 1500 or 2000, the most extreme 
 precision in the balance of the aberrations must necessarily be 
 realised, since the slightest imperfection so prodigiously magnified 
 would become injuriously apparent. 
 
 The extreme degree of perfection, which has been attained in 
 the best class of microscopes, may be imagined, when it is stated, 
 that an object which is distinctly visible under a power of 1500 
 or 2000, when it is exposed to the object-glass uncovered, will be 
 sensibly affected by aberration if a piece of glass, no more than 
 the 100th of an inch in thickness, be laid upon it. InfinitesimaUy 
 small as is the aberration produced by such a glass film, it is 
 sufficient, when magnified by such a power, to be perceptible, and 
 to impair in a very sensible manner the distinctness of the image. 
 
 As it has been found necessary, for the preservation of micro- 
 scopic objects, to cover them with such thin films of glass, through 
 which, consequently, they are viewed, adjustments are provided 
 in microscopes with which the highest class of powers are supplied, 
 by which even the small aberration due to these thin plates of 
 glass thus covering the objects can be corrected. This is effected 
 by mounting the lenses, which compose the triple object-piece, 
 in such a manner that their mutual distances, one from another, 
 can be varied within certain small limits, by motions imparted to 
 them by fine screws. This change of mutual distance produces a 
 small effect upon the aberrations, rendering their total results 
 negative to an extent equal to the small amount of positive 
 aberration produced by the thin glass which covers the object. 
 20. The eye-glass and the field-glass are both plano-convex 
 24 
 
EYE-PIECES. 
 
 lenses, having their plane sides turned towards the eye ; they are 
 set in opposite ends of a brass tube, varying in length from two 
 inches downwards, according to their focal lengths, the distance 
 between them and, consequently, the length of the tube being 
 always equal to half the sum of their focal lengths. 
 
 The higher the power of the eye-piece, and consequently the 
 shorter the focal length of the eye-glass, the less will be the length 
 of the tube in which they are set. 
 
 This tube is called the eye-piece. 
 
 It will be apparent from what has been explained, that the 
 magnifying power of the instrument will depend conjointly on 
 those of the object-piece and eye-piece. 
 
 21. In the prosecution of microscopic researches, the use of 
 very various magnifying powers is indispensable; the higher 
 powers would be as useless for the larger class of objects, as the 
 lower ones for the smaller. But even for the same object, a 
 complete analysis cannot be accomplished without the successive 
 application of low and high powers : by low powers the observer 
 is presented with a comprehensive view of the entire form and 
 outline of the object under examination, just as an aeronaut who 
 ascends to a certain altitude in the atmosphere obtains a general 
 view of the country, which would be altogether unattainable 
 upon the level of the ground. By applying successively higher 
 powers, as has been already explained, the smaller parts and 
 minuter features of the object are gradually disclosed to view, 
 just as the aeronaut, in gradually descending from his greatest 
 altitude, obtains a view of objects which were first lost in the 
 distance, but at the same time loses, by too great proximity, the 
 general outline. 
 
 The microscope-makers, therefore, supply in aU cases an 
 assortment of powers, varying from 30 or 40 upwards ; observa- 
 tions requiring powers under 40, being more conveniently made 
 with simple microscopes. For this purpose it is usual, with the 
 best instruments, to furnish six or eight object-pieces and three 
 or four eye-pieces, each eye-piece being capable of being combined 
 with each object-piece. The number of powers thus supplied will 
 be equal to the product of the number of object-pieces, multiplied 
 by the number of eye-pieces. 
 
 The powers, however, may still be further varied, by provi- 
 sions for changing the distance between the object and eye-pieces, 
 within certain limits. For this purpose, the tube of the instru- 
 ment is sometimes divided into two, one of which moves within 
 the other, like the tube of a telescope, the motion being produced 
 by a fine rack and pinion : in this case the eye-piece is inserted in 
 one of the tubes, and the object-piece in the other. By combining 
 
 25 
 
THE MICROSCOPE. 
 
 Fig. 12. 
 
 this provision with a proper assortment of object-pieces and eye- 
 pieces, all possible gradations of power between the highest 
 attainable, and the lowest which is applicable, can be obtained. 
 
 The actual magnitude of the space which can be presented at 
 once to the view of the observer, will vary with the magnifying 
 power ; but in all cases it is extremely minute. Thus, with the 
 lowest class of powers, where it is largest, it is a circular space, 
 the diameter of which does not exceed the 8th or 10th of an inch ; 
 it follows, therefore, that no object, the extreme limits of whose 
 linear magnitude exc^d this, can be presented at once to the 
 view of the observer. Such objects can only be seen in their 
 ensemble, by means of less powerful magnifying glasses, or with 
 the naked eye. 
 
 22. The field of view, with powers from 100 to 300, varies in 
 diameter from the 15th to the 40th of an inch ; from 300 to 500 
 it varies from the 40th to the 70th of an inch ; and from 500 to 
 700 from the 70th to the 100th of an inch. 
 
 It will thus be understood, that even with the moderate power 
 of 700, an object to be included wholly within the field of view, 
 must have a magnitude such as may be 
 included within a circle whose diameter 
 does not exceed the 100th of an inch. 
 These observations will be more clearly 
 appreciated by reference to the annexed 
 diagram, fig. 12, where a is a circle 
 whose diameter is the 6th of an inch ; 
 B one whose diameter is the 12th of an 
 inch ; c the 25th, D the 50th, and E the 
 100th. 
 
 But when still higher powers are used, 
 the actual dimensions of the entire space 
 comprised within the field of view will be 
 so very minute, that an object which 
 would fill it, and still more, smaller 
 objects included within it, would not only 
 be altogether invisible to the naked eye, 
 but would require considerable micro- 
 scopic power to enable the observer to see them at all. 
 
 The actual dimensions of the field of view, which correspond to 
 each magnifying power, vary more or less in different instru- 
 ments. Those which I have given above, are taken from a 
 microscope made by Charles' Chevalier, which is in my possession. 
 The difference however in this respect, between one instrument 
 and another, is not considerable, and the above will serve as a fail 
 illustration of the limits of the field of instruments in general. 
 26 
 
FIELD OF VIEW. 
 
 The entire dimensions of the field of view therefore being so 
 exceedingly minute, it will be easily understood that some diffi- 
 culty will attend the process by which a small object, or any 
 particular part of an object, can be brought within it : thus, with 
 a moderate power of 500, the entire diameter of the field being no 
 more than the 70th of an inch, a displacement of the object to 
 that extent, or more, would throw it altogether out of view. If 
 therefore the object, or whatever supports it, be moved by the 
 fingers, the sensibility of the touch must be such as to be capable 
 of producing a displacement thus minute. 
 
 If the object be greater in its entire dimensions than the field 
 of view, — a circumstance which most frequently happens, — a part 
 only of it can be exhibited at once to the observer ; and to enable 
 him to take a survey of it, it would be necessary to impart to it, 
 or to whatever supports it, such a motion as would make it pass 
 across the field of view, as a diorama passes before the spectators, 
 disclosing in slow succession all its parts, and leaving it to the 
 power of the observer to arrest its progress at any desired moment, 
 so as to retain any particular part under observation. 
 
 The impracticability of imparting a motion so slow and regular 
 by the immediate , application of the hand to the object, or its 
 support, will be very apparent, when it is considered that while 
 the entire object may not exceed a small fraction, say, for exam- 
 ple, the 20th of an inch in diameter, the entire diameter of the 
 field of view may be as much as 20 times less, so that only a 20th 
 part of the diameter of the object would be in any given position 
 comprised within it. 
 
 23. These and similar circumstances have rendered it necessary 
 that the want of sufficient sensibility and delicacy of the touch in 
 imparting motion to the object, shall be supplied by a special 
 mechanism, by means of which the fingers are enabled to impart 
 to the object an infinitely slower and more regular motion, than 
 they could give it without such an expedient. The means by which 
 this is accomplished will be presently explained. 
 
 We have seen that the intensity with which the microscopic 
 image is Uluminated depends on the angle of aperture, other 
 things being the same ; but however large that angle may be, 
 when considerable magnifying power is used, it is necessary that 
 the object itself should be much more intensely illuminated than 
 it would be by merely exposing it to the light of day, or that of 
 the most brilliant lamp. It is therefore necessary to provide 
 expedients, by which a far more intense light can be thrown 
 upon it. 
 
 24. The instrument is said to be in Foctrs when the observer is 
 enabled to see with the eye-glass the magnified image of the 
 
 27 
 
THE MICROSCOPE. 
 
 object witli perfect distinctness ; this will take place provided the 
 mutual distances between the eye-piece, the object-piece, and the 
 object are suitably adjusted ; and this adjustment may be accom- 
 plished by moving any one of these three towards or from the 
 other two, while these last remain fixed : thus, for example, if the 
 object and the object-piece remain unmoved, the instrument may 
 be brought into focus by moving the eye-piece to or from the 
 object-piece. The rack and pinion, already described, which 
 moves the tube in which the eye-piece is inserted, can accomplish 
 this. This provision, however, is not made in all microscopes. 
 
 If the eye-piece and the object be fixed, the instrument may be 
 brought into focus by moving the object-piece to or from the 
 object. To effect this, it would be necessary that the object-piece 
 should be inserted in a tube, moved by a rack and pinion, like 
 that of the eye-piece. 
 
 In fine, if the object-piece and eye-pieco be both fixed, the 
 instrument may be brought into focus by moving the object, or 
 whatever supports it, to or from the object-glass. 
 
 All these methods are resorted to in the different forms in 
 which microscopes are mounted by different makers. 
 
 25. Since nearly all material substances, when reduced to an 
 extreme degree of tenuity, are more or less translucent, and since 
 almost all microscopic objects have that degree of tenuity by 
 reason of their minuteness, it happens that nearly all of them are 
 more or less translucent ; and where in exceptional cases a 
 certain degree of opacity is found, it is removed without inter- 
 fering with its structure, by saturating the object with certain 
 liquids, which increase its translucency, just as oil renders paper 
 semi-transparent. The liquid which has been found most useful 
 for this purpose, is one called Canada balsam. When the object 
 is saturated with this liquid, it is laid upon a slip of glass, about 
 two inches long and half an inch wide, and is covered with a 
 small piece of very thin glass, made expressly for this purpose, 
 the thickness in some cases not exceeding the 100th of an inch. 
 It is usual to envelope the oblong slip of glass, in the middle of 
 which the object is thus mounted with paper gummed round it, a 
 small circular hole being left uncovered on both sides of tha 
 glass, in the centre of which the object lies. 
 
 The slips of glass thus prepared, with the objects mounted 
 upon them, are called slides or sliders • and the objects thus 
 mounted are so placed, that the axis of the object-piece shall be 
 directed upon that part of them which is submitted to observa- 
 tion, provisions being made to shift the position of the slider, so 
 as to bring all parts of the object successively under observation, 
 further provisions are also made to throw a light upon the 
 28 
 
SLIDERS — MOUNTING. 
 
 object, by wbicli it will be seen as an object is on painted 
 glass. 
 
 Since, however, there are some few objects which cannot be 
 rendered translucent, expedients must be provided, by which 
 they can be illuminated upon that side of them which is presented 
 to the microscope. It is often necessary, also, even in the case of 
 translucent objects, that they should be viewed by means of light 
 thrown upon that side of them which is turned to the object- 
 glass. 
 
 26. These general observations being premised, we shall pro- 
 ceed to explain the method by which the optical part of the 
 instrument is mounted, and the several accessories by which the 
 object is supported, moved, and illuminated. 
 
 Let us suppose, for the present, that the eye-piece e f, fig. 13, 
 and the object-piece o, are mounted in a vertical tube, with 
 whose axis AAA, the several axes of the lenses, accurately co- 
 incide. Let d dhe a. diaphragm, or blackened circular plate, with a 
 hole in its centre, placed in the focus of the eye-glass, by which 
 all rays of light not necessary to form the image shall be inter- 
 cepted. Let D be a milled head, by turning which the tube 
 which carries the eye-piece can be moved within certain limits to 
 and from the object-piece, and let d' be another milled head, by 
 which the tube which carries the object-piece can be moved 
 within certain limits to and from the object, or by which the 
 entire body B B of the microscope, carrying the object-piece and 
 eye-piece, can be moved to and from the object. 
 
 27. Let s s be a flat stage of blackened metal or wood, having 
 a circular hole in its centre, as shown in plan at s' s', and let it 
 be fixed by proper arrangements, so that the axis A A A of the 
 microscope shall pass through the centre of the circular aperture, 
 and so that its plane shall be at right angle to that axis. Let a 
 slider, such as we have described above, upon which an object is 
 mounted, be laid upon this stage, so that the object shall be in 
 the centre of the hole, and therefore in the axis AAA of the 
 microscope. 
 
 28. Let It M be a concave reflector, receiving light either from 
 a lamp or a window, and reflecting it upwards towards the open- 
 ing in the slider, in converging rays, so as to condense the light 
 with more or less intensity upon the under side of the object ; if 
 the convergence produced by ar M be insufl&cient, it may be 
 augmented by the interposition of a convex lens c c. This may 
 or may not be interposed, according as the object is smaller or 
 greater, and requires a more or less intense illumination. 
 
 The light being thus thrown upon the lower side of the object, 
 the latter, being sufliciently translucent, is rendered visible by it, 
 
 2S) 
 
THE MICROSCOPE. 
 
 Fig. 13. 
 
 30 
 
ILLUMINATING APPARATUS. 
 
 If the object be opaque, it may be illuminated from above by 
 several expedients ; being placed upon a blackened plate resting 
 on the stage s s, light proceeding from a -window or a lamp may 
 be condensed upon it by a concave reflector m' m', or by a convex 
 lens L L. Q^hese arrangements, however, are only applicable 
 when the object is at such a distance from the object-piece that the 
 light proceeding from M.' m' or L L shall not be wholly or partially 
 intercepted by the object-piece. This would always be the case, 
 however, when very high powers are used, and when, conse- 
 quently, the object must be brought very close to the object- 
 piece. In that case, the object is supported upon a small piece 
 of blackened cork, or in a dark cell of the form represented at 
 w w ; this support is placed in the centre of the opening of the 
 stage, so as not to intercept any but the central rays reflected 
 from 31 M ; upon the end of the object-piece a concave reflector, 
 having a hole in its centre, through which the object-piece passes, 
 is fixed ; the light proceeding from m m, and falling upon this 
 reflector, is reflected by it, so as to converge upon the object, and 
 thus to illuminate it. 
 
 A concave illuminator thus mounted is called, from its inventor, 
 a lieherkuhn, 
 
 29. In the illumination of objects it is frequently necessary to 
 limit, to a greater or less extent, the diameter of the pencil of 
 light thrown from the reflector, m m, upon the object. Although 
 this may partly be accomplished by varying the distance of the 
 reflector from the object, or by the interposition of a convex lens, 
 such expedients are not always the most convenient, and a much 
 more ready and effectual method of attaining this end is supplied 
 by providing below the stage, s s, a circular blackened disc, 
 capable of being turned upon its centre in its own plane. This 
 disc is pierced with a number of 
 . holes of different diameters, as shown 
 in flg. 14, and it is so mounted, that 
 the openings in it, by turning it 
 round its centre, may be brought 
 successively under the object. This 
 is easily done by fixing the centre 
 of this disc at a distance from the 
 centre of the stage, equal to the 
 distance between the centre of the 
 disc and the centres of the holes 
 made in it. 
 
 This appendage is called the disc 
 of diaphragms, and is of great use in the illumination of objects, 
 as will appear hereafter. 
 
 31 
 
THE MICEOSCOPE. 
 
 As the effect of tlie illuminators varies not only with tlieir 
 distance from the object, but also with the direction in which the 
 light directed from them falls upon the object, provisions are 
 made in mounting the microscope, by which various positions may 
 be given to them, so that the light may fall upon the object in any 
 desired manner. 
 
 In the frame in which the illuminator, M M, is mounted, it is 
 ■customary to place two reflectors, one at each side, one concave 
 and the other plane. By the former a converging, and by the 
 latter a parallel pencil of light is reflected towards the object. 
 
 In this general illustration we have supposed the axis of the 
 instrument to be vertical ; it may, however, have any direction 
 whatever; but whatever be its direction, the stage, s s, must 
 always be at right angles and concentric with it. The eye-piece 
 and object-piece are also supposed to be set in the same straight 
 tube, with their axes set in the same straight line. This arrange- 
 ment, though most commonly adopted, is neither necessarily nor 
 always so. The tube which carries the eye-piece may, on the 
 contrary, be inclined, at any desired angle, with that which 
 carries the object-piece ; for this purpose it is only necessary to 
 place in the angle formed by the two tubes a reflector, so inclined 
 that the rays coming from the object-piece shall be reflected along 
 the axis of the tube which carries the eye-piece. 
 
 32 
 
'ig. 46.— nachet's multiple mickoscope. 
 
 THE MICROSCOPE. 
 
 CHAPTER III. 
 
 30. Oblique plane reflectors The support and moyemext of the object : 
 ™f i-' ^Y^^^^^^sm for focussing.-S.S. Coarse adjust- 
 
 ment.--34 Fine adjustment. -35. Method of determining the relief 
 of an object.-36 Difficulty of bringing the object into the field.-ilV. 
 
 Sv^'^^Q n?1.^^T!"^°''--^.^-?^^^^™ ^^^^ the object 
 40 Sltirf 'i Y successively viewed by increasing powers.- 
 40 S idestobecleaned.-41. Compressor. -42. Apparatus for apply, 
 mg voltaic current. The iLLumNATiON of objects : 43. Curious efifects 
 If J'' objects.— 44. lUumination by transmission and reflection. 
 —45. Microscopic objects generally translucent, or may be made so. 
 lad; %f ^^^yf f tliif .^^^^^^^ Varying effects of light and 
 
 l.^ 'T f' Lieberkuhn.-49. Effects of diffraction 
 
 and interference -50. Use of daylight.-51. Artificial light.-52. 
 ilWnation ' Pritchard's analysis of the effects of 
 
 Lardner's Museum of Science. d 
 No. 110. 
 
THE MICROSCOPE. 
 
 30. Thus, for example, if the tube wHch carries tlie object- 
 piece be vertical, a plane reflector, m m, fig. 15, receiving tbe rays 
 
 ¥ig. 15. 
 
 0' 
 
 coming in a vertical direction from tlie object-piece, will reflect 
 them horizontally to the eye-piece e e. 
 
 The same object would be attained with more advantage, and 
 less loss of light, by means of a rectangular prism, A b c, fig. 16, 
 
 Fiff. 17. 
 
 A 
 
 Fis:. 18. 
 
 the vertical ray, r h' being reflected by the back, A C, of the prism 
 in the horizontal direction n' e". 
 
 Since a single reflection thus made produces an inverted image, 
 34 
 
THE STAGE. 
 
 it is sometimes preferable to accomplish the object by two sue- 
 cessive reflections, as shown in fig. 17, where the ray, a b, is 
 successively reflected at b and c to the eye at b. And the same 
 object may be attained more advantageously by means of a 
 quadrangular prism, as shown in fig. 18. 
 
 This application of the prism and reflector has been already 
 explained in our Tract upon Optical Images. 
 
 Much practical convenience often arises from the adoption of 
 this expedient ; thus, while the object-tube is directed vertically 
 <lownwards, to an object supported on a horizontal stage, or 
 floating on or swimming in a liquid, the eye-tube may be hori- 
 zontal, so that the observer may look in the level direction. In 
 this case the two tubes are fixed at right angles, the reflecting 
 surface being placed at an angle of 45° with their axes. We 
 shall see hereafter a case in which, by the adoption of an oblique 
 tube, several observers may at the same time, looking through 
 different eye-pieces, see the same object through one and the 
 same object-glass. 
 
 THE STJPPOET AlTD MOVEMEITT OF THE OBJECT. 
 
 31. The appendage of the microscope, adapted for the support 
 of the object is called the stage. 
 
 Since every motion or disturbance by which the stage may be 
 affected will necessarily be increased, when seen through the 
 microscope, in the exact proportion of the magnifying power, it 
 is of the utmost importance that it should be exempt from all 
 tremor, and that it should have strength sufficient to bear, with- 
 out flexure, the pressure of the hands in the manipulation of the 
 object. "When a high power is used, the focal adjustment of 
 tlie instrument requires to be so exact, that a displacement of 
 the object, which would be produced by the slightest pressure 
 of the fingers upon a stage not very firmly supported, would 
 throw it out of focus. 
 
 If the instrument be used for dissection, or any other purpose 
 in which steady manipulation of the object is needed, it will be 
 found convenient that the stage have sufficient magnitude to 
 support both wrists, while the operation is performed with the 
 fingers. Supports for the elbows ought also to be arranged, so as 
 to place the operator completely at ease. 
 
 32. The instrument is focussed, as already explained, either by 
 moving the stage to and from the body, or by moving the body 
 to and from the stage. The motion is imparted to the one or the 
 other by means of a milled head placed on the right of the 
 observer, which leaves a pinion working in a rack to which the 
 
 D 2 35 
 
THE MICROSCOPE. 
 
 part to be moved is attached. By turning tMs milled head one- 
 way and the other alternately, the observer finds by trial the 
 position which gives greatest distinctness. 
 
 33. This, which is called the coaese adjustment, answers 
 well enough when high powers are not used; but it must be 
 remembered that as the teeth of the pinion successively pass those 
 of the rack, the motion produced is not strictly an even and 
 uniform one, but a sort of starting or intermitting motion, so that 
 the instrument cannot be easily and steadily brought to rest at 
 any intermediate point between the beginning and the end of the 
 passage of a tooth. "When high powers are used, and conse- 
 quently an extremely nice adjustment of the focus required, this 
 arrangement is therefore insufficient, and serves at best only for a 
 first approximation to the exact focus. 
 
 34. A supplemental expedient is therefore provided in the 
 best instruments, called the fine adjustment, which usually 
 consists of a screw having an extremely fine thread, which 
 being connected with the part to be moved, gives it a per- 
 fectly smooth, uniform, and slow motion, entirely free from starts 
 or jerks. 
 
 In some of the best instruments these screws have as many as 
 150 threads to the inch, so that one complete turn of the milled 
 head moves the stage or body through only the 150th part of an 
 inch, and as the head is divided into ten equal parts and moves 
 under an index, a tenth of a revolution can be observed, which 
 corresponds to the 1500th part of an inch. 
 
 When the form of the object is not actually flat, and conse- 
 quently all points upon it are not equally distant from the object- 
 glass, they will not be all in focus together. When the distance 
 of the object is such as to bring the more salient, and conse- 
 quently the nearest, parts into focus, the more depressed parts 
 will be too distant and consequently out of focus ; and when the 
 object is moved nearer to the object-glass by a space equal to the 
 heights of the salient above the depressed parts, the latter will be 
 in, and the former out of focus, and consequently the latter will 
 be distinct, and the former confused. 
 
 When the powers used are so low that the distance of the 
 object from the object-piece shall bear a considerable proportion 
 to the difference of level of the salient and depressed parts of the 
 object, this difierence of level will not sensibly affect the focal 
 adjustment ; but when high powers are used, that difference of 
 level bearing a very sensible proportion to the distance of the 
 object from the object-glass, the adjustment which renders either 
 distinct will render the other indistinct. 
 
 35. This optical fact has been converted with admirable address 
 3G 
 
COAESE AND FINE ADJUSTMENTS. 
 
 into an expedient, by whicli the inequalities of the surface of a 
 microscopic object are gauged, and its accidents analysed. Thus, 
 for example, let the milled head of the fine adjustment be first 
 turned so as to render the salient parts distinct, and let the 
 position of the index be marked. Let it be then turned so as to 
 render the depressed parts distinct, and let the new position of 
 the index be marked. If one division of the head represent the 
 1500th part of an inch, the differences of level, of the salient 
 and oppressed parts, will be just so many 1500ths of an inch as 
 there are divisions of the milled head which have passed the 
 index. 
 
 86. One of the first difficulties which the microscopic debutant 
 encounters, is that which will attend his attempts to bring the 
 object into the centre of the field of view when it is minute, and 
 when the magnifying power is considerable. If he is only pro- 
 vided with a simple stage, without any mechanical expedient for 
 moving the object, he will soon be oppressed with the fatigue 
 arising from a succession of abortive attempts at accomplishing 
 Ms purpose. 
 
 37. The entire diameter of the field of view will often be less 
 than the 100th of an inch, so that a displacement of the slide so 
 inconsiderable as to be utterly insensible to his fingers, will cause 
 the object to jerk through a space greatly exceeding the entire 
 extent of the field. In this way the object will start from side 
 to side, the motion imparted to it by the touch to bring it back 
 to the field being always in excess, however carefully and deli- 
 cately the manipulation may be made. Some professional 
 observers, by intense and long- continued practice, surmount this 
 difficulty and succeed in adjusting the slides, even with the 
 highest powers, without mechanical aid; but this is not to be 
 hoped for by debutants or amateurs, except with very low magni- 
 fying powers. Such persons, if they would avoid the risk of 
 throwing up the instrument with disgust^ had therefore better in 
 all cases be provided with a stage having some such expedients as 
 we shall now describe. 
 
 Upon the fixed stage, such as it has been described, a second 
 stage similar in form and equal in size is placed, and is moveable 
 through a certain limited space right and left, by a fine screw 
 with a milled head. Another similar stage is placed upon this, 
 which partakes of any motion imparted to the latter, but which 
 is also moveable upon the latter backwards and forwards by means 
 of another fine screw. Upon this last stage the slide with the 
 object is placed, and held down by springs so as to retain its 
 place, whatever be the position of the stage. 
 
 By turning one of these screws (fig. 19), the object may be 
 
 37 
 
THE MICROSCOPE. 
 
 slowly moved right and left, and by turning tlie other it may be- 
 
 Fig. 19. 
 
 moved backwards and forwards, 
 and, in fine, by turning both 
 at the same time it may be 
 moved diagonally in any inter- 
 mediate direction, according to 
 the relative rate at which the 
 one and the other milled head 
 is turned. Sometimes the two- 
 milled heads are on the right 
 side of the stage, so that they 
 can be turned either separately or together by the right hand, 
 and sometimes they are placed at opposite sides, so as to engage 
 both hands. 
 
 38. It is generally found convenient to have an easy means of 
 turning the object round its centre, so as to present it to the light 
 in aU possible positions, without displacing it from the centre of 
 the field. This is accomplished by inserting in the upper plate 
 of the stage a metallic disc of somewhat greater diameter than 
 the central aperture of the stage, which is so fixed as to be turned 
 smoothly round its centre. It is upon this disc that the slide is 
 placed and held by the springs which are attached to the disc so 
 as to turn with it. This disc is sometimes graduated in 360°, so 
 that the observer can turn the object through any desired angle, 
 a power which will be found very convenient in certain classes 
 of observations. 
 
 The arrangement consisting of a fixed with two moveable 
 
 stages superposed is 
 drawn in fig. 20, 
 where a a a ais the 
 fixed stage, and b b 
 b b, c cc c the two 
 stages which move 
 in the grooves n n 
 and m m, the one 
 bbbb directed right 
 and left, and the 
 other c c 0 c back- 
 wards and for- 
 wards. The grooves 
 in which the upper 
 stage c c c c moves 
 
 are formed in the lower stage bbbb, and those in which the 
 latter moves are formed in the fixed stage aa aa. The one 
 stage is moved by turning the milled heads s s fixed upon the 
 38 
 
MOTION OP OBJECT. 
 
 rod tt, and the other by turning the head rr fixed upon the 
 hollow rod v, through which 1 1 passes. 
 
 Another and more simple form of moveable stage is shown in 
 fig. 21, where a a a represents a circular brass disc, having a 
 circular aperture in its p. 
 centre. Upon this a 
 second disc 6 6 6 is 
 placed, which is moved 
 within certain limits in 
 two directions, at right 
 angles to each other, 
 by the screws v v', 
 against which the spring 
 E I p L reacts. The 
 entire stage is in this 
 case moveable round its 
 own centre. 
 
 By these expedients 
 the observer has com- 
 plete command over the 
 object, so as to be able 
 to move it at pleasure 
 
 in any direction, with a motion which will be smooth, slow, and 
 free from jerks and starts, even when magnified with the highest 
 powers. 
 
 To centre the object, that is, to place it on the stage so that its 
 centre shall be in the centre of the field, is not so easy as it 
 might appear to the unpractised in microscopic manipulation. 
 To accomplish this, let the slide be first laid across the aperture 
 of the stage, the object being as nearly as possible concentric with 
 the aperture. Let the, stage and object-glass be brought nearly, 
 but not actually, into contact by the coarse adjustment. Let the 
 slide be then again centred, so as to render the object concentric 
 with the object-glass. Let the stage be then moved from the 
 object-glass until the instrument is focussed as nearly as it can 
 be by the coarse adjustment. Let the object be then more 
 exactly centred by the stage-screws, and more exactly focussed 
 by the fine adjustment. 
 
 It must not, however, be supposed that this elaborate process is 
 necessary in the case of every class of objects. The larger sort 
 can be easily enough centred by the hand, and focussed by the 
 coarse adjustment ; and in the cheaper description of microscopes 
 no other means are provided. For a smaller sort, the centring- 
 may be efiected by proximity with the object-glass, and rendered 
 more exact with the fingers when no stage-screws are provided. 
 
 39 
 
THE MICllOSCOrE. 
 
 But mucli trouble will be produced when objects of tbe smallest 
 class requiring the liighcr powers are examined with instru- 
 ments in Avhich the stage-screws and fine adjustments are not 
 supplied. 
 
 39. In all cases it will be found advantageous to submit the 
 objgct successively to a series of increasing powers. When once 
 centred it will maintain its place while the object-lenses are 
 changed, so that upon each change of power no new adjustment is 
 necessary except focussing. The low powers will show the 
 general form and contour, the entire object being at one and the 
 same moment within the field. The next powers will show the 
 larger parts, and the highest will display the texture of the sur- 
 face and the structure of the smaller parts. By working the 
 stage-screws the object is moved like a panorama across the field 
 from right to left ; and this motion is repeated for various posi- 
 tions given to it by the screws, which move it backward and 
 forward until every part of it has been submitted to examination. 
 
 When high powers are used the object will be very close to 
 the object-glass, so as almost to touch it when the instrument is 
 focussed. In this case, care should be taken to prevent all 
 contact or friction of the object or the slide with the object-glass, 
 the latter being subject from that cause to injury or fracture. 
 When it is desired therefore to change an object thus viewed with 
 a high power, it is always advisable to separate the object-glass 
 and stage by the coarse adjustment, before removing the one 
 object and replacing it with the other, which must then be 
 focussed. 
 
 40. The greatest care should be taken to clean the slides before 
 placing them on the stage, since the least particle of grease or 
 dust or any other foreign matter would, when magnified, injure 
 the observation and might lead to errors. 
 
 When the object observed is in a drop of water or other liquid, 
 or when it is itself a liquid, it will be included between the 
 slide and a thin glass placed upon it, in which case it is of the 
 greatest importance to exclude or remove all bubbles of air, since 
 they would present appearances under the microscope, such as 
 would deface those of the proper object of observation. 
 
 41. When it is required to submit a minute object to inspec- 
 tion, it is sometimes desirable to submit it to pressure, either to 
 retain it in one position, if it be living, or to ascertain the effect 
 of compression upon it, exercised in a greater or less degree for 
 other purposes. It is often necessary also to roll it over, so as to 
 present aU sides of it in succession to the observer. 
 
 An instrument called a compressor has been contrived for this 
 purpose, which has been constructed in a great variety of forms 
 40 
 
COMPRESSOE. 
 
 by different makers, according to tlie demands of different 
 observers. 
 
 One of tlie most common and useful forms of compressor is 
 shown in fig. 22. 
 
 A small and very thin disc of glass is set in a brass ring i, and 
 supported at two points L l, diametrically opposite, by the ends of 
 a fork L p, attached to j,. 
 a lever p g, the latter 
 being supported upon 
 two upright pieces F, 
 attached to an hori- 
 zontal piece r d. This 
 piece r d turns hori- 
 zontally round a pivot, 
 fixed near the end e 
 
 of a strong slip of brass A B, having the form and magnitude of a 
 slide used for the support of objects. At the middle c, of A b, is 
 a circular hole, in which another disc of glass is set, correspond- 
 ing in magnitude to the disc i. A screw, with a milled head K, 
 works in the end g of the lever, by turning which in one way or 
 the other, the end g, and consequently the disc i, is raised or 
 
 To place the object for observation, by moving the piece d 
 round the pivot the ring i is removed from the lower disc c, 
 upon which the object is then deposited. The screw k being 
 turned, so as to raise the disc i sufficiently to prevent it from 
 touching the object, the piece D is then turned on the pivot 
 until the disc i is brought over the object. The observer 
 then viewing the object in the microscope, and placing 
 his hand upon the screw k, slowly turns it, so as gradually to 
 compress the object, and continues this process or suspends it, or 
 turns the disc i horizontally, so as to roll the object between the 
 glasses, according as his course of observation may require. 
 
 The compression may be so increased as to flatten the object, 
 which in some cases is desired, so as to render it more transparent, 
 while nevertheless its form becomes more or less distorted. 
 
 42. It is sometimes required to ascertain the effects of an 
 electric spark or voltaic current, transmitted through a liquid or 
 solid, or through a body animate or inanimate. An apparatus 
 adapted for this purpose is shown in fig. 23, where d c is a disc 
 of glass set in the middle of a slip of brass a b. The two brass 
 tubes G G play upon the hinges F f, which are supported on short 
 glass pillars e e. Two glass tubes, through the bores of which 
 fine platinum wires a a pass, are inserted tightly into the tubes 
 G G, so that they can be pushed to, or drawn from the disc r, 
 
 41 
 
THE MICROSCOPE. 
 
 where tiie object is placed. The positive and negative ends of 
 the conductor of the electric machine, or the poles of a voltaic 
 battery, being put in connection with the handles 6 5 of the 
 
 Fig, 23. 
 
 platinum wire, the spark or current will pass from the point of 
 cnc of the wires a a to that of the other, being transmitted through 
 the object placed between them. 
 
 THE ILLUMINATION OF OBJECTS. 
 
 43. Among the accessories of the microscope, there is none the 
 right use of which is more important than the illuminators. By 
 the proper application of these, an infinite variety of beautiful 
 effects are produced, and an infinite number of interesting con- 
 sequences developed, while by their abuse, and by the misconcep- 
 tion and misinterpretation of their indications, the most fatal 
 errors and illusions may arise. 
 
 Let any one, however inexperienced in the manipulations of a 
 microscope, applying one hand to the mirror and the other to the 
 disc of diaphragms, vary at pleasure the position of the former, 
 and turn the latter slowly round its centre, thus shifting the 
 direction, and varying the quantity of the light which falls upon 
 the object, and he will witness, in looking at the object through 
 the instrument, a series of appearances which will soon demon- 
 strate to him how curious, complicated, and important a part the 
 illuminators play in microscopical phenomena. 
 
 44. Objects may be rendered visible in two ways, either by 
 light reflected from those parts of their surfaces which are pre- 
 sented towards the observer, or by light falling on the posterior 
 surface, and partially transmitted through them. Opaque bodies 
 can be seen only in the former way, but translucent objects may 
 be seen in either of these ways. 
 
 A translucent object presents a different appearance, according 
 as It is seen by a front or back light. The leaf of a tree or plant, 
 seen by reflected light, appears to have some particular tint of 
 42 
 
ILLUMINATION OF OBJECTS. 
 
 green, showing faint traces of a certain reticulated skeleton of 
 vegetable fibre. If it be held up before tbe sun, all light being 
 excluded from the side presented to the eye, it will appear with a 
 much paler tint of green, and the skeleton will become much 
 more visible, the finer parts before invisible being distinctly- 
 seen. 
 
 A stained glass-window viewed from the outside appears to 
 have dark and dull colours, and might be taken to be opaque, 
 showing no form or design. Yiewed from the inside, forms of 
 great beauty, and colours of remarkable splendour, are seen. 
 
 When we say, therefore, that objects viewed in a microscope 
 present very different appearances, according as they are illu- 
 minated by a front or a back light, we only state a general fact 
 common to all visible objects. 
 
 No body can be said to be either opaque or transparent in an 
 absolute sense. Bodies considered to be the most opaque, such 
 as the metals, are found to be translucent when reduced to thin 
 leaves. Even gold and platinum, the most dense of the metals, 
 are rendered translucent under the hammer of the gold-beater, 
 while glass, diamond, air, water, and similar bodies, commonly 
 considered to be transparent, are proved to absorb a portion of the 
 light transmitted through them, this absorption increasing with 
 the thickness of the medium. There is in fine no body which 
 will not become opaque if sufficiently thick, and none that wUl 
 not become more or less translucent if sufficiently thin. 
 
 45. Since microscopic objects are generally of extremely 
 minute dimensions, they are all, with some few exceptions, suf- 
 ficiently translucent to be rendered visible by a back light. 
 
 It is well known that many bodies, which are opaque or nearly 
 80, may be rendered translucent by saturating them with certain 
 liquids. Thus, as every one knows, paper, linen, and other 
 porous bodies, which when dry are imperfectly translucent, 
 become much more so when wetted or oiled, or saturated with 
 white wax. 
 
 This general physical fact has special and important application 
 in the preparation of microscopic objects, which are saturated 
 with various liquids, proper for each of them, by which they are 
 rendered translucent. 
 
 When a translucent object is rendered visible by a back light, 
 the intensity of the light must be regulated according to its 
 translucency. The more translucent it is, the less intense must 
 be the light. A strong back light thrown upon a very trans- 
 lucent object drowns it, and renders it altogether invisible. The 
 light must therefore be reduced in intensity by varying the incli- 
 nation of the reflector, the distance of the lamp from it, and by 
 
 43 
 
THE MICROSCOPE. 
 
 the interposition of smaller diaphragms, until the best effect is 
 produced. The observer will acquire by practice a facility in 
 making these adjustments, so as to produce the desired result. 
 
 On the other hand, if the object be very imperfectly trans- 
 lucent, the light thrown upon it must be rendered as intense as 
 possible by the contrary arrangements. 
 
 46. Different parts of the same object will generally have 
 different degrees of translucency, and it will often happen that a 
 light which would drown the more transparent parts will be no 
 more than sufficient to display the more opaque parts. In such 
 cases the observer will have to vary the light according as his 
 attention is directed to one part or the other. 
 
 It must not be inferred that the darker parts are in this case 
 really darker than those which are more transparent. The 
 lesser degree of translucency more frequently arises from the 
 different thickness of different parts of the object, the thicker 
 parts absorbing more light, and therefore appearing of a darker 
 tint than the thinner. If the varying transparency arise from this 
 cause, the apparent lights and shadows or tints of colour must be 
 taken as mere indications of the inequalities of thickness of a 
 body of which the real colour is uniform. 
 
 The difificulty which an observer encounters in ascertaining the 
 real form of an object, and the accidents of its surface when seen 
 in a microscope by a back light, is partly owing to the fact that 
 the eye is habituated to view objects a:lmost exclusively by front 
 lights, and the impressions produced of their forms are always 
 deductions of which we are rendered unconscious by habit, by 
 which the characters of these surfaces are inferred from the lights 
 and shadows which are impressed on the organ of vision. Not 
 having the same habit of seeing objects by a back light we cannot 
 so easily make similar deductions, and we are apt to judge of the 
 objects as if in fact they were illuminated with a front light. 
 
 The judgment is also more or less perplexed, and deceived by 
 the fact that microscopic objects are as it were placed before the 
 eye in an unnatural state of proximity, which give them a visual 
 character totally different from that which objects have, viewed 
 in the usual way with the nalted eye. 
 
 It must be evident, therefore, how much attention and address 
 on the part of the observer are indispensable to enable him to 
 disentangle their physical causes from such complicated effects, 
 and to give their appearances a right interpretation. 
 
 47. if an object, of which the surface is marked by numerous 
 inequalities and asperities, be illuminated by a light which falls 
 perpendicularly upon it, or which is scattered indifferently in all 
 directions, an observer placed directly over it will be in general 
 
 44 
 
ILLUMINATION OF OBJECTS. 
 
 unable to perceive the elevations or depressions, all being pro- 
 jected upon the same ground-plan, and all being similarly illu- 
 minated. But if tbe light fall upon it with a certain and regular 
 obliquity, lights and shadows will be produced which will enable 
 him to infer the accidents of the surface and the real form of the 
 object. 
 
 The due consideration and application of this general optical 
 fact will enable the microscopic observer to submit the object of 
 his inquiry to such a visual analysis as will unfold at least a close 
 approximation to its real form. 
 
 48. If the object be viewed by a front light proceeding from 
 the concave mirror M M, fig. 13, or reflected by the Lieberkuhn, 
 this effect wiU not be produced ; for although the light reflected 
 from the Lieberkuhn is not perpendicular to the object, it is scat- 
 tered in all possible directions, so as utterly to remove all possi- 
 bility of lights and shadows. An expedient is sometimes adopted 
 in which light projected by a concave mirror or lens, properly 
 placed, is directed only on one side of the Lieberkuhn, which is 
 necessarily productive of lights and shadows. 
 
 But the purpose is much more simply and effectually attained 
 by removing the Lieberkuhn altogether, and directing the illu- 
 mination with the necessary obliquity upon the object by means 
 of a reflector or lens placed as shown at m' m.' or l l. 
 
 Those methods are always practicable except when a magnifying 
 power is used so high as to render it necessary to bring the object 
 almost into contact with the object-glass, in which case the 
 mounting of the latter would intercept the light, whether pro- 
 ceeding from the Lieberkuhn, the lens, or mirror. In such cases 
 the object can only be illuminated by a back light. 
 
 If the object be illuminated by a back light thrown obliquely 
 upon it, the lights and shadows, strictly, speaking, can only be 
 produced upon the posterior surface. Nevertheless, the light 
 passing obliquely through the anterior surface will produce dark 
 and light tints, according to the angle at which it strikes the 
 several superficial inequalities and accidents of that side of the 
 object. It will be evident, therefore, that very complicated effects, 
 in which the disentanglement of the forms which produce them 
 is extremely difficult, must ensue. 
 
 Nevertheless, the attentive and practised observer, by presenting 
 the illumination successively in various directions, by properly 
 varying its intensity, and examining the object as well by front 
 As by back illumination, when both are practicable, can generally 
 arrive at a pretty clear knowledge of its form and parts. 
 
 49. When the object is illuminated by a back light, optical 
 phenomena, called diffraction and interference, are produced, 
 
 45 
 
THE MICROSCOPE. 
 
 against which the observer must be on his guard. The effects of 
 these are to surround the outline of the object with coloured fringes. 
 By limiting the illumination as far as it is practicable to the object 
 itself, so as to avoid the transmission of any light through the 
 opening of the slide, except what may pass through the object, 
 this effect may be diminished or avoided. 
 
 Indeed, for many reasons, it is advantageous to prevent any 
 light from passing through the slide, or through the opening of 
 the stage, except what is employed in illuminating the object. 
 All such light is liable to fall in greater or less quantity upon the 
 object-glass, and, passing through it, has a tendency to render the 
 image obscure and confused. For this reason, all extraneous 
 light whatever should be as far as possible excluded from the 
 space around the microscope, for all objects on which such light 
 falls will reflect a part of it, some of which may fall upon the 
 object-glass. 
 
 50. When the light of the sky or clouds is used, an aperture 
 maylje made in a window-shutter for its admission, all the other 
 windows of the room being closed, and the light proceeding 
 from the aperture being received upon the mirror or lens, by 
 which it is directed and condensed upon the object. The light 
 of a white cloud, strongly illuminated by the sun, is generally 
 considered the best form of day-light which can be used, and 
 that of a blue serene sky the worst. Observers differ as to the 
 direct light of the sun, some maintaining that in no case what- 
 ever should it be used, while others give it a preference for 
 minute objects seen under high powers, and therefore requiring 
 intense illumination. 
 
 The light reflected from a white wall upon which the sun 
 shines is a good source of illumination. 
 
 51. If artificial light.be used with low powers, a common sperm 
 handle will serve well enough, but means should be adopted to 
 prevent the flickering of the flame. 
 
 An argand lamp, however, is, in all cases, preferable, as giving 
 a steady invariable light. It will be improved if good olive oil 
 be used instead of the fish oil. 
 
 The flame produced by the liquid known as camphine is 
 especially pure and white^ and well fitted for microscopic 
 researches. 
 
 Whatever be the artificial light used, it ought to be surrounded 
 with a shade, and so placed as to fall only upon the mirror or 
 lens by which it is directed to and condensed upon the object. 
 
 52. It is advantageous to protect the eyes of the observer from 
 extraneous light: the most simple and convenient method of 
 -effecting which is by a cii'cular blackened pasteboard screen 
 
 46 
 
ILLUMINATION OF OBJECTS. 
 
 about a foot in diameter, having a liole in its centre, througli 
 which, the tube of the eye-piece is passed. This screen is then 
 at right angles to the axis of the body of the instrument, the 
 eye-piece ^projecting about an inch from it. The observer looking 
 into the eye-glass with one eye, need not incur the exertion and 
 fatigue of closing the other, since the screen performs the office of 
 the eye -lid. 
 
 , The mirrors are sometimes made with a concave glass at one 
 side, and a plane glass at the other, the latter being used when 
 condensation is not required. A disc formed of plaster of Paris, 
 reduced to an extremely even and smooth surface, either plane 
 or concave, is sometimes used with advantage when a soft and 
 mild light is required. Nearly the same effect may be produced 
 by placing a disc of white card upon the face of the mirror. The 
 illumination by a back light is attended with a peculiar advan- 
 tage, inasmuch as it displays the internal structure of objects, 
 and, in the case of organised bodies, supplies beautiful means of 
 exhibiting the circulation ; as, for example, the circulation of the 
 blood in animals, and the sap in vegetables. In the case of certain 
 animalcules, it shows some living and moving within the bodies of 
 others. 
 
 53. The following observations of Mr. Pritchard are worthy of 
 attention: — "We must consider that in all bodies viewed by 
 intercepted light, there is, properly speaking, neither light nor 
 shade, in the ordinary acceptation of these terms ; there are only 
 dark and light parts, which again assume new aspects as the light 
 is more or less direct or oblique. Thus depressions on transparent 
 objects are almost sure, under the action of oblique light, to 
 assume the effect of prominences ; but prominences seldom or 
 never have the semblance of depression. As almost all diaphanous 
 bodies can be examined as opaque objects, a scrutiny of them in 
 this way will generally be found greatly to assist our judgment 
 concerning their nature, whether they admit of being cut into 
 sections or not. It would be easy to write a volume on this 
 subject only, if we commenced an illustration of particulars which 
 could not be rendered clear and satisfactory without a vast number 
 of figures. Long practice must, after all, determine our opinions, 
 and scepticism should ever form a leading feature in them ; we 
 should suspect rather than believe* 
 
 Opaque objects are not, upon the whole, so liable to produce 
 optical deceptions as transparent ones, because we are more in tlie 
 habit of viewing ordinary bodies by reflected or radiated light. 
 The most common illusion presented by them is that of showing a 
 basso-relievo as an alto-relievo ; the reverse deception sometimes 
 occui's also, but more rarely. This effect occurs in ordinary objects 
 
 47 
 
THE MICROSCOPE. 
 
 viewed by the naked eyes, as well as in microscopes, especially if 
 but one eye is employed. Thus, if we look intently for some 
 time at a basso-relievo (a die of a coin, for example), illuminated 
 with very oblique lights it at first appears in its true character ; 
 but, after a little while, some point on which we more particularly 
 direct our gaze will begin to appear in alt. the whole rapidly 
 follows ; in a little time the effect wears off, and we again see it 
 in bas-relief ; then agaii in alt ; and so on, by successive fits. 
 This deception arises from the simple circumstance that the lights 
 and shades in bas-relief are very nearly like those of an alto- 
 relievo of the same subject, illuminated from the opposite side ; 
 our understanding in this case instantly corrects the false testi- 
 mony of the eye, when we consider from which side the light 
 comes. (If we observe with a microscope, we must remember that 
 its image is inverted, and that in consequence the light must be 
 considered as proceeding from the side of the field of view oppo- 
 site to that where the source of illumination actually exists.) It 
 will also be highly advisable, when we are in doubt as to the 
 manner in which an instrument shows prominences and depres- 
 sions, to verify its vision by observiag some known object with it, 
 of the real state of which, as to inequality of surface, we have 
 been previously informed by the sense of touch, to which it has 
 been well said there is no fellow." * 
 
 * * ' We usually see objects illuminated from above with the shadows below 
 the prominences ; now, unless the light is below an opaque object, when 
 we view it in an engiscope, we shall see the shadows above, giving the 
 prominences the appearance of depressions, and producing a very unnatural 
 effect. " 
 
 48 
 
Fig. 36.— FRArrEilHOFfER's MlCROSCOPiS. 
 
 THE MICROSCOPE. 
 
 CHAPTEE IV. 
 
 Pritchard's analysis of the effects of illumination (continued). Mea- 
 surement OF OBJECTS : 54. Measurement distinct from magnifying 
 power. — 55. Measurement by comparison with, a known object. — 
 56. Micrometric scales. — 57. Thin glass plates. — 58. Micrometers. 
 — 59. Le Baillif's micrometer. — 60. Jackson's micrometer. — 61. 
 Measurement by the camera lucida. — 62. Groniometers. Magni- 
 fying Power : 63. This term much misunderstood. — 64. Its exact 
 meaning. — 65. Least distance of distinct vision. — 66. Visual esti- 
 mate of angular magnitude. — 67. Method of determining magnifying 
 power by the camera lucida. — 68. Dimensions of the least object 
 which a given power can render visible. 
 
 Lardner's Museum of Science, e 49- 
 
 No. 112. 
 
THE MICROSCOPE. 
 
 ** Illumination, by cups or silver specula, does not produce these 
 illusions, -because tbey create no shade — the whole object is one 
 mass of intense light ; other false perceptions are, however, occa- 
 sioned by them. Thus, all globular bodies, having polished sur- 
 faces, reflect an image of the cups, and the spout, if there is one, 
 appears as a dark spot in the centre. The eyes of insects, illumi- 
 nated in this way, show the semblance of a pupil in the centre of 
 each lens, which deception may be verified by examining small 
 globules of mercury in the same manner. Spherical bodies, with 
 bright surfaces, will even, on some occasions, reflect an image of 
 the object-glass and its setting, on the same principle ; so that 
 we must perpetually consider the laws of the refraction and reflec- 
 tion of light, in all the conclusions we draw from the evidence 
 even of the very best instruments, used with every possible 
 precaution. 
 
 Lastly, it must be observed, that in using microscopes, we 
 must never attempt to verify an object concerning which we are 
 uncertain, by increasing the depth of the eye-glass immoderately, 
 so as in this way to obtain a very high power. A negative eye- 
 glass, of about one-fourth of an inch focus, is the deepest which 
 should ever be employed, even with a short body ; for a microscope 
 only shows a. picture of an object, and the more it is amplified the 
 more its imperfections are developed. It is, on this account, 
 much safer to trust to moderate powers in these instruments, in 
 preference to high ones, unless they are obtained through the 
 medium of the depth and power of their objective part. It is the 
 nature of deep eye-pieces to cause all luminous points to swell out 
 into discs, and to render the image soft, diluted, and nebulous, 
 at length all certain vision fades away, and the imagination is 
 left to its uncontrolled operation. Single and compound magni- 
 fiers, having to deal with the real object, may be made of any 
 power which can be used ; and if our eyes are strong, and habi- 
 tuated to their use, we may place great reliance on their testis 
 mony ; but we must never allow them to persuade us to believe 
 marvels which are manifestly impossible, or contrary to the known 
 laws of nature and right reason." 
 
 MEASUREMENT OP OBJECTS. 
 
 54. The determination of the real magnitude of microscopic 
 objects, and that of the magnifying power of the instrument, are 
 problems closely connected but not identical. Either may be 
 solved independently of the other. 
 
 55. If two objects be placed at the same time within the field 
 of view, the real magnitude of one of which is known, that of the 
 other may be at least approximately estimated by comparison, 
 
 50 
 
MEASUEEMENT OF OBJECTS. 
 
 Since they are equally magnified, their real will be in the propor- 
 tion of their apparent magnitudes. If, therefore, they appear 
 equal, they will he equal, and if that which we desire to measure 
 appear to be twice or half the size of that whose magnitude we 
 know, its real magnitude will be twice or half that of the latter. 
 
 Such was the micrometric method used by the earlier observers. 
 Thus Lewenhoeck procured a number of minute grains of sand, 
 sensibly equal in magnitude, and placing as many of them in a 
 line, and in contact, as extended over the length of an inch, he 
 ascertained the fraction of an inch, which expressed the diameter 
 of each. When he desired to ascertain the actual magnitude of an 
 object seen with his microscope, he placed one of these grains 
 beside it, and estimated by comparison the magnitude of the 
 former. 
 
 Yarious natural objects, whose magnitudes are known, and 
 which are subject to no perceptible variations, such as the sporules 
 of Lycoperdon bcvista or puff-ball, whose diameter is the 8500th 
 of an inch, those of the lycopodium, which measures the 940th 
 of an inch, and others such as hair, the filaments of silk, flax, 
 and cotton, and the globules of blood, have been suggested aa 
 standard measures to be similarly used. 
 
 More modern observers, adhering to the same method, have 
 substituted artificial for natural standards. Thus extremely fine 
 wire, called micrometric wire, has been used. This wire can be 
 drawn with an astonishing degree of fineness. Dr. "WoUaston 
 invented a process by which platinum wire was produced, whose 
 thickness was only the 30000th part of an inch.* 
 
 56. Such measurements are now more generally made by means 
 of a minute scale engraved on glass, with a diamond point. Let 
 us suppose, for example, a line, the 20th of an inch in length, 
 traced across the centre of a glass disc, set in a thin brass plate 
 of the size and form of the sliders on which objects are mounted. 
 Let this line be divided into 100 equal parts, every fifth division 
 being distinguished by a longer line, and every tenth by a still 
 longer one. Each of these divisions will be the 2000th part, 
 the intervals between the fifth divisions will be 400th, and that 
 between the tenth divisions the 200th part of an inch. This 
 microscopic scale wiE be seen magnified with the microscope, and 
 any microscopic object laid upon it will be seen equally magnified, 
 so that its dimensions can be ascertained by merely counting the 
 divisions of the scale included between those which mark its 
 limits when placed in different positions on the scale. 
 It may perhaps be thought impracticable to make divisions so 
 
 * Handbook of Natural Philosopliy, 2d edition, Mechanics, 38, 
 K 2 51 
 
THE MICROSCOPE. 
 
 minute upon tlie glass, with the necessary precision, especially 
 when it is remembered that any error or inequality will necessarily 
 be augmented in the exact proportion of the magnifying power 
 with which such a scale is seen. Nevertheless this difliculty has 
 been most successfully overcome, and combinations of screws and 
 
 Fig. 24. 
 
 wheels have been contrived, by which the diamond point is moved 
 by self-acting mechanism, so as to trace the successive divisions 
 of scales of astonishing minuteness. Scales are thus produced, 
 the divisions of which are no greater than the 25000th part of 
 an inch. 
 
 This extreme minuteness is, however, rarely necessary or desira- 
 ble in microscopic researches, and the divisions of the scales in 
 more common use vary from the 1000th to the 2000th of an inch. 
 In the scales delivered with moderately good French instruments, a 
 millimetre is divided into one hundred parts. A millimetre being 
 about the 25th of an inch, these divisions would therefore be the 
 2500th of an inch. (See Tract on Microscopic Drawing and En- 
 graving, Museum, vol. vi.) 
 
 The process described above, in which the object is measured 
 by superposition upon the micrometric scale, is attended with 
 several practical difficulties and objections. The object, when 
 thus placed, is always nearer to the object-glass than the scale, 
 and when it is in focus, the scale is out of focus and invisible ; 
 and, on the other hand, when the scale is in focus, the object is 
 out of focus and indistinct. When low powers only are used, 
 this difference between the focus of the object and that of the 
 scale being inconsiderable, will not prevent the success of the 
 operation ; but when the powers are high, it can never be satis- 
 factorily, and sometimes not at all effected. 
 
 There is stiU another objection to the process. The placing and 
 displacing of objects frequently on a surface so delicately engraved, 
 subjects it to friction, which soon spoils and effaces the divisions. 
 
 If the divided surface be protected, as it may be, by a plate of 
 glass laid upon it, the difference between the distances of the 
 object and the scale from the object-glass is augmented by the 
 52 
 
MEASUREMENT OF OBJECTS. 
 
 thickness of the glass -which covers the scale ; and however thm 
 this glass may be, where high powers are used, it will render the 
 difference of the foci of the scale and the object so sensible, that 
 they can never be both seen with sufScient distinctness at the 
 same time. 
 
 57. We know no greater example of the inexhaustible resources 
 of art, and the untiring zeal with which its cultivators minister to 
 the wants of science, than the wonderful perfection to which the 
 mechanical division of a material so fragile as glass has been 
 carried. For the reasons we have here stated, as well as because 
 in the application of the highest magnifying powers the object- 
 glass of a microscope requires to be almost in contact with the 
 object, without actually touching it, microscopists required 
 extremely thin plates of glass to cover delicate objects mounted 
 on their slides. Messrs. Chance of Birmingham responded to this 
 demand by the production of plates of glass so thin, that three 
 hundred of them piled one upon the other are no higher than 
 an inch. 
 
 For examples still more striking of the minuteness with which 
 lines may be traced upon glass by mere mechanical processes, we 
 may refer the reader to that part of our Tract upon Microscopic 
 Drawing and Engraving, in which the test plates of Mr. Robert 
 are described. 
 
 58. One of the most evident expedients for the measurement of 
 microscopic objects would seem to be the micrometer screw, which 
 is applied with so much success, and with results of such extreme 
 precision, in astronomical instruments. Various methods of apply- 
 ing it to the microscope will suggest themselves to every one who is 
 familiar with its uses in the observatory. Let two filaments of 
 spider's web, or micrometric wire, be extended at right angles 
 across the field in the focus of the Fig. 25. 
 eye-piece. These will divide the field 
 horizontally and vertically at right 
 angles, intersecting at its centre, as 
 shown in fig. 25. Now suppose 
 the stage supporting the object is 
 capable of being moved by a micro- 
 meter screw, having for example 
 one hundred threads to the inch. 
 Let the object be placed first so that 
 its length shall be horizontal, and 
 let the slip be adjusted so that 
 the vertical micrometric wire b h' 
 shall coincide with one of its extremities. Let the micrometex 
 screw be now turned so that the object shall move horizon- 
 
 53 
 
THE MICROSCOPE. 
 
 tally. It will appear to pass gradually under the vertical wire 
 until its other extremity shall coincide with that wire. If then 
 the number of complete turns, and parts of a turn of the screw 
 be counted, the length of the object then will be known. Thus, 
 if at the end of every complete turn, the screw produce an 
 audible sound like the tick of a clock, the observer can count 
 the complete turns, and if the circumference of the head be 
 divided into 100 parts, and that an index be fixed upon the 
 stage to indicate the position of the head at the commence- 
 ment, the decimal parts of a turn can be ascertained, each division 
 of the head corresponding to the 100th part of a complete turn, 
 and therefore to the 10000th of an inch. 
 
 By turning the stage so that the screw will cause the object 
 to move across the field in the direction of the vertical wire, its 
 dimensions in the other direction can be ascertained. 
 
 59. A simple and iEgenious micrometer for ascertaining the 
 dimensions of such objects as would bear a slight pressure without 
 change of form, was invented by M. Le BaiUif. A plan and 
 vertical section or side view of this are shown in fig. 26. 
 
 Tw(i upright pieces, c c, are fixed in a slip of copper, formed 
 like one of the slides, having a circular hole in its centre, in 
 
 Fig. 26. 
 
 A B 
 
 which is set a plate of glass, on which a scale o is engraved* 
 Upon this is placed a moveable piece, e e, having a similar hole 
 and plate of glass, with a fine line engraved upon it at right angles 
 to the scale, so that when it is moved from left to right this fine 
 line will coincide necessarily with all the divisions of the scale. 
 From this piece, two rods proceed, which pass through holes in the 
 upright pieces c c, and one of them is reacted upon by a piece of 
 watch-spring, /, while the other abuts against the end of a fine 
 screw, /, which moves in a nut, d. 
 
 When an object is to be measured, the index line upon the 
 upper glass disc is brought to coincide with the first division or 
 54 
 
MICROMETERS. 
 
 zero of the scale by turning the head / so as to cause the screw to 
 retire from the piece e e, the spring / then pressing this piece tor 
 wards the screw. The object to be measured is then inserted 
 between the end of the rod projecting from e and the screw, and 
 consequently the piece e e and the index line engraved upon it 
 will be pushed from left to right through a space equal to the 
 thickness of the object. This thickness may then be ascertained 
 by observing with the microscope the division of the scale to 
 which the indicating line has been advanced, 
 
 60. A micrometer, having some resemblance to this, but made 
 more applicable to the general purposes of microscopic measure- 
 ment, has lately been contrived by Mr. Jackson, a description of 
 which is published in the "Transactions of the Microscopical 
 Society." 
 
 A disc of glass, upon which a micrometric scale is engraved, is 
 set in a thin plate of brass, which moves with a sliding motion on 
 another plate, in which a corresponding hole is made. The former 
 is like that of M. Le Baillif, urged by a fine screw in one direc- 
 tion, and driven back by a spring in the other, as shown in fig. 24. 
 
 Fig. 21. Fig. 28. 
 
 • This micrometer slide is inserted in the tube of the eye-piece by 
 openings in the sides of the tube, as shown at m in fig. 27, which 
 openings can be closed when the micrometer is not used by sliding 
 covers, as shown at o, fig. 28, 
 
 It is easy to see how this contrivance is applied. The scales 
 magnified by the eye-glass are projected upon the optical image of 
 the object produced by the object-glass, and this image may be 
 made to move so as to bring its extremity to coincide with the first 
 division of the scales. The scale will then show not only the dimen- 
 sions of the entire object, but those of its parts. The object may 
 be turned in any direction relatively to the scale that may be 
 desired, by means either of the hand or the stage adjustments. 
 
 55 
 
THE MICROSCOPE. 
 
 It is necessary, however, before applying this micrometer to 
 the measurement of objects, to ascertain the value of the divi- 
 sions of the scale relatively to the object, since the immediate 
 subject of its measurement is, not the object itself, but the optical 
 image of the object produced in the focus of the eye-piece by the 
 object-glass ; and this preliminary valuation is the more necessary, 
 inasmuch as the relative magnitude of the image, compared with 
 that of the object, will vary with the power of the object-piece. 
 
 To ascertain, then, the value of the divisions of the scale, let 
 another micrometric scale, the divisions of which are known, be 
 placed upon the stage. An image of this scale, magnified as that 
 of an object would be, will then be formed in the focus of the 
 eye-piece, and the other scale will be seen projected upon it. Let 
 the position of the two scales be so adjusted by the stage arrange- 
 ments thai the first division of the one shall be projected on the 
 first division of the other. By observing then the next divisions 
 of the two which coincide, the relative value of the scales will be 
 known. Thus if ten divisions of the eye-piece scale exactly cover 
 100 divisions of the other, and if each division of the latter be the 
 1000th of an inch, one division of the eye-piece scale will corre- 
 spond to the 10000th part of an inch in the dimensions of an object. 
 
 It is evident that the value of the divisions of the scale should 
 be determined for each object-piece which the observer uses. 
 
 61. The combination of the camera lucida with the micro- 
 metric scale has supplied a very simple and convenient method of 
 measuring microscopic objects. 
 
 It has been shown in our Tract upon The Camera Lucida, 
 that by that instrument the image of an object magnified in any 
 desired proportion can be thrown upon a sheet of paper upon, 
 which its outline can be traced. The micrometric scale is first 
 thus projected, and its divisions, or as many of them as are con- 
 sidered necessary, are traced upon the paper. Another similar 
 series of divisions being traced at right angles to the former, the 
 part of the paper corresponding to the field of view is divided into 
 a system of squares, like those into which a map is divided by the 
 lines of latitude and longitude. The micrometric slide being 
 removed from the stage, the slide with the object is substituted 
 for it, and the observer sees the image of the object similarly 
 magnified projected upon the paper, already spaced out by the 
 squares. He can therefore count the number of squares occupied 
 by its length and breadth, and by the length and breadth of its 
 several parts, or, better still, he cau trace its outline upon the 
 paper, so that its dimensions and those of all its parts can be 
 exactly ascertained. Thus, if each division of the scale is the 
 1000th of an inch, the side of each square will represent the 
 56 
 
MICKOMETERS. 
 
 lOOOth of an inch, and these sides may themselves be easily sub- 
 divided into ten or 100 parts, so as to carry the measurement to 
 lOOOOths or lOOOOOths of an inch. 
 
 In fig. 29 the field of view is represented spaced out in this 
 manner, with the outlines of objects traced upon it. 
 
 Such a scale once drawn upon the paper, will serve for the 
 measurement of any objects which may be submitted to the 
 microscope ; but it is most essential that in all such measurements 
 the paper be kept at exactly the same distance from the camera, 
 and that neither the object-glass, the eye-glass, nor the stage 
 shall suffer any change in their relative positions. 
 
 Fig. 29. 
 
 It has been shown that the magnitude of the image received on 
 the paper increases with the distance of the paper from the 
 camera. If, therefore, the paper be placed at a greater or less 
 distance from the camera to receive the image of the object than 
 that at which it was placed to receive the image of the micro- 
 metric scale, the image of the object will be produced upon a scale 
 greater or less than that on which the image of the micrometrie 
 scale was produced, and conseq[uently the one cannot be taken as 
 a measure of the other. 
 
 If any change be made in the relative positions of the eye- 
 
THE MICKOSCOPE. 
 
 piece, object-piece, and stage, a corresponding change would he- 
 made in the magnifying power of the instrument, and a conse- 
 quent change in the dimensions of the picture of any object 
 projected by the camera on the paper, though no change be made 
 in the distance of the paper from the camera. 
 
 In fine, the method of measuring the actual dimensions of a 
 microscopic object by means of a scale drawn with the aid of the 
 camera, requires that the instrument and the paper shall be in 
 precisely the same state when the image of the object is projected 
 on the paper as they were when the scale was drawn upon the 
 paper. 
 
 If this condition be observed, measurements can be made by 
 the camera with all the necessary facility and precision. 
 
 62. In microscopic researches it is frequently necessary to 
 measure the angles at which the lines which form the contour of 
 objects are inclined to each other. Various forms of goniometers * 
 have been contrived for this purpose. One of the most simple 
 and convenient of these consists of a circular plate of brass c c, 
 fig. 30, having a central opening in which a disc of glass is set, 
 on which a diameter <7 6 is engraved with a diamond point. 
 Upon this, and concentric with it, another similar plate, toothed 
 at the edge, is placed, having also a disc of glass of the same 
 magnitude set in it, with a diameter a c in like manner engraved 
 upon it. Upon the plate c c an ear is cast, in which a pinion is 
 inserted, which, working in the teeth of the second disc, gives it 
 a motion round its centre, by which the diameter a c is made 
 successively to assume all possible angles with the diameter d h. 
 This piece is inserted in the eye-piece A b, a side view of which 
 30 31 is shown in fig. 31, so as to be 
 
 concentric with the lenses, and 
 to coincide with the focus of 
 the eye-lens. The lines a c 
 and h d will then be seen pro- 
 jected on the image of the 
 object, and if the vertex of the 
 angle it is desired to measure 
 be brought, by means of the stage adjustments, to coincide 
 with the centre o of the disc abed, where the two engraved 
 diameters intersect, and so that one side of the angle to be 
 measured shall ceincide with the fixed line d b, the line a c can 
 be turned by the pinion F, until it shall coincide with the other 
 side. A graduated circle which surrounds the disc will then 
 show the magnitude of the angle at which b d and a c are inclined. 
 
 * From the Greek word y6vv (gonu), knee. 
 
 58 
 
MAGNIFYING POWER. 
 
 THE MAGNIFYING POWEH. 
 
 63. It has been well said, that a question clearly put is half 
 resolved. There is no term Id microscopic nomenclature so 
 familiar to the ear, and so flippant on the tongue, as the " magni- 
 fying power;" yet there is none respecting which there prevail 
 so much confusion and obscurity. The chief cause of this is the 
 neglect of a clear and distinct definition of the term. 
 
 It has been already shown, that the magnitudes observed with 
 the microscope are visual, not real. "We can say that such or 
 such an object seen in the microscope has a magnitude of so many 
 degrees, but not at all one of so many inches. Strictly speaking, 
 the same is true of all objects seen in the ordinary way ; but in 
 that case the mind is habituated to form an estimate of their real 
 magnitudes, by combining the consideration of their apparent 
 magnitudes with their distances. It is true that we are uncon- 
 scious of the mental operation from which such estimates result, 
 but it is not the less real. Our unconsciousness of it arises from 
 the force of habit, and the great quickness of the acts of the 
 mind. Every one who has been familiar with intellectual pheno- 
 mena knows that such unconsciousness is found to attend all such 
 acts as are thus habitual and rapid. 
 
 64. But when objects are looked at in a microscope, the mind 
 not only does not possess the necessary data to form such an 
 estimate, but the conditions under which the visual perceptions 
 are formed are so unusual, and, so to speak, unnatural, that it is 
 incapacitated to form an approximate estimate even of the visual, 
 to say nothing of the real, magnitude of the object of its 
 perception. 
 
 The visual magnitude of an object, as seen in a microscope, is 
 the angle of divergence of lines supposed to be drawn from the 
 eye to the limits of the imaginary image formed by the eye-glass, 
 which is the immediate object of perception. When we say, 
 therefore, that the instrument has such or such a magnifying 
 power, every one will comprehend that it is meant that this visual 
 magnitude is so many times greater than the visual magnitude 
 which the object would have, if it were seen in the usual way 
 without the interposition of any optical expedient. 
 
 So far all is clear, and so far there can be no difference of 
 opinion on the point, provided only that the latter member of the 
 sentence be clearly defined. "What is the "visual magnitude 
 seen in the usual way ? " There are many ways of looking at an 
 object, and " the usual way" depends much on the magnitude 
 of the object. "We can see well enough the dome of St. Paul's 
 Cathedral at the distance of half a mUe, while we cannot see a 
 
 59- 
 
THE MICROSCOPE. 
 
 small insect at the distance of a yard. The same object may be 
 viewed at different distances, and will have different visual mag- 
 nitudes, these magnitudes being greater as the distance is less. 
 The visual diameter of a small object, seen from the distance of a. 
 yard, is three times less than when seen from the distance of a 
 foot. It appears, therefore, that the "visual magnitude of an 
 object seen in the usual way with the naked eye," is a term of 
 comparison which, without some further condition to limit it, has 
 no fixed meaning, and consequently leaves the " magnifying 
 power" of which it is made the standard, altogether vague and 
 indefinite. 
 
 65. The visual magnitude therefore which is made the standard 
 of magnifying power, must be the visual magnitude at some 
 arbitrary distance conventionally assumed. As we have already 
 stated, it has been generally agreed, since micrography has taken 
 the rank of a special branch of science, to adopt ten inches as the 
 standard distance. This distance is recommended not merely on 
 account of the arithmetical facility which arises out of its decimal 
 character, but because it agrees sufficiently for all practical 
 purposes with the standard derived from the measures of other 
 countries. In France, for example, the standard usually adopted 
 is twenty-five centimetres, which is equal to 9-427 inches, being 
 less than ten inches by only about the sixth of an inch. 
 
 According to this convention, then, the magnifying power of a 
 microscope would be the number of times the visual diameter of 
 the object viewed with the microscope is greater than its visual 
 diameter viewed by an eye placed at ten inches from it. Thus, 
 if the visual diameter of an object seen at the distance of ten 
 inches be fifteen minutes of a degree, and the visual magnitude of 
 the same object seen with a microscope be two and a half degrees, 
 or 150 minutes, the magnifying power will be ten. 
 
 But an objection will even still be raised. The object may be 
 so small that at the distance of ten inches it would not be visible 
 at all with the naked eye. Nay, it may be, and in the case of 
 microscopic objects often is, so minute that it would not be per- 
 ceptible to the naked eye at any distance, however small. In 
 that case it maybe asked, What is to be understood by "its visual 
 magnitude at the distance of 10 inches ?" 
 
 This point will require some explanation. There is a certain 
 limit of magnitude within which an object will cease to make any 
 sensible impression of its magnitude or form upon the eye. This 
 minor limit of magnitude varies with different individuals, and, 
 in the case of the same individual, with different objects according 
 to their colour, illumination, the ground on which they are pro- 
 jected, and many other conditions which it is not here necessary to 
 60 
 
MAGNIFYING POWEK. 
 
 discuss. It will suffice to say that there is such a limit. If the 
 visual angle formed by lines diverging from the eye to the extre« 
 mities of the object be within this limit, the object will not be per- 
 ceived ; or, to speak with more rigour, its magnitude and form 
 will not be perceived.* 
 
 In such cases, therefore, the visual magnitude of an object, 
 without the intervention of the microscope, must be understood 
 to mean the angular divergence of the rays which would be drawn 
 from a point placed at ten inches from the object to its extremities. 
 This would be the visual magnitude of the object ^^if it could he 
 seen" at that distance. . 
 
 In fine, therefore, the definition of the magnifying power of a 
 microscope will be clear, distinct, and adequate, if it be stated 
 thus : — It is the quotient which would be obtained by dividing 
 the visual magnitude of the object, as seen in the microscope, by 
 the visual magnitude which the object would have to a naked eye 
 placed at ten inches distance from it, supposing the eye to have 
 sufficient sensibility to perceive it at that distance. 
 
 Every one is more or less familiar with real magnitude, so that 
 when an object of ordinary dimensions is placed before them they 
 can give at least a rough estimate of its actual dimensions. The 
 same facility of estimating visual magnitude does not exist, 
 although, in fact, we receive the impressions of visual much more 
 frequently than those of real magnitude. The estimate of visual 
 magnitude, however, enters into all microscopic inquiries as an 
 element and condition of such importance, that all those who use 
 the instrument, whether for the purposes of serious research or 
 rational amusement and instruction, would do well to familiarise 
 themselves with it. Some observations illustrative of such sen- 
 sible impressions wiU therefore, we presume, be not unacceptable 
 to our readers. 
 
 66. Our great familiarity with real magnitude arises from our 
 intimate knowledge of certain standard units by which it is 
 counted. There is no one, however little educated, that has not 
 a pretty clear notion of the length expressed by an inch, a foot, 
 and a yard. Let us see whether we may not enable any one with 
 common attention to acquire an equally clear notion of the 
 standard units of visual magnitude. 
 
 Every one is familiar with the apparent magnitude of the disc 
 of the full moon. It is visible to the whole world, and seen for 
 several nights in each month during the entire life of every indi- 
 vidual. Now it happens that the visual magnitude of its diameter 
 
 * The fixed stars are visible as mere luminous points, but their forms 
 and magnitudes are not perceivable, owing to the extreme smallness of 
 their visual angle produced by their enormous distances. 
 
 61 
 
THE MICROSCOPE. 
 
 Fig. 32. 
 
 is just half a degree, which means, that the angular divergence of 
 lines drawn from the eye to the extremities of the diameter is the 
 same as that of two lines drawn from the centre of a circle to the 
 extremities of an arc, which is the 720th part of the entire circle. 
 Every one, therefore, who is familiar with the appearance of the 
 full moon, will be as familiar with the meaning of a visual angle 
 of half a degree, and, consequently, of a degree as they are with 
 the real magnitude of an inch or a foot. 
 
 The distance of the moon has been ascertained to be 120 times 
 its own diameter, and it is evident that any circular disc whatever, 
 whose distance from the eye is 120 times its own diameter, will 
 have a visual angle equal to the diameter of the moon, and there- 
 fore to half a degree ; and, consequently, one whose distance is sixty * 
 times its own diameter, would have a visual angle of a degree. 
 
 Thus, in fig. 32, there are five white discs shown upon a black 
 ground : the diameter of the first is the 6th of an inch ; that of 
 the second, the 12th ; that of the third, 
 the 25th ; the fourth, the 50th ; and 
 the fifth, the 100th. If these be held at 
 ten inches from the eye, the fii'st disc, 
 A, will have a visual angle of 1° ; the 
 second, b, one of 30' ; the third, c, 
 about 15'; the fourth, D, 7|'; and, in 
 fine, the fifth, e, 3|'. 
 
 It follows, therefore, that an object 
 which when viewed with a magnifying 
 power of 1000, appears with the same 
 visual diameter as the moon, or as the 
 disc B, fig. 32, placed at 10 inches from 
 the eye, must have a real diameter no 
 greater than the 12000th part of an 
 inch. 
 
 Having familiarised himself with 
 some such standards of visual magnitude 
 as these, and once knowing the magnifying power of his instru- 
 ment, an observer can easily make a rough estimate of the real 
 magnitudes of the objects under view. 
 
 67. But for this, as well as many other purposes of microscopic 
 research, it is necessary that the actual magnifying power of the 
 instrument be ascertained. 
 
 The most simple and direct means of accomplishing this are 
 supplied by the camera lucida. 
 
 * More strictly 57*3 times ; but the round number will be sufficient for 
 the above illustration. 
 62 
 
MAGNIFYING POWER. 
 
 Let a inicrometric scale, sucli as we have already described, be 
 placed on the stage, the instrument focussed, the camera attached, 
 and a sheet of paper placed at 10 inches from it. An image of 
 the scale being seen on the paper, let any two contiguous divisions 
 of it be marked with the pencil. Let the distance between these 
 marks be then exactly measured, and let it be divided by the 
 actual length of the divisions of the scale. The quotient wHl be 
 the magnifying power. 
 
 Thus, for example, let us suppose that the micrometric scale is 
 the 25th part of an inch, and that this length is divided into 100 
 parts, each of these parts will be the 2500th part of an inch. Now 
 suppose that it is found that the distance between the images of 
 two contiguous divisions on the paper, is four-tenths of an inch. 
 It will follow that the visual magnitude of a division of the scale 
 is magnified in the proportion of to ^, that is, as 1 to 1000, 
 The magnifying power would therefore be a thousand. 
 
 There are other methods of ascertaining the magnifying power, 
 but this is so simple, so easily produced, and so precise, that we 
 shall not detain the reader by any notice of others. 
 
 Microscopes being generally supplied with several object- 
 glasses, and eye-pieces, the observer and amateur would do 
 well once for all to ascertain the magnifying powers of all the 
 possible combinations of them, and to tabulate it and keep it for 
 reference. 
 
 68. It is often asked, What are the dimensions of the most 
 minute object which a microscope, having a given magnifying 
 power, is capable of rendering distinctly visible ? 
 
 The answer to this question will depend on the answer to 
 another ; What are the least dimensions of the same object, with 
 which it would be distinctly visible, at ten inches distance, with 
 the naked eye ? 
 
 Whatever be the latter dimensions, the former will be just so 
 many times less as there are units in the number which expresses 
 the magnifying power. 
 
 Thus, for example, if the smallest linear dimensions with 
 which the object could be distinctly seen without a glass at 10 
 inches distance were the 300th part of an inch, a microscope 
 having a magnifying power of 500 would render such an object 
 equally visible if its linear dimensions were only the 300 X 500 
 = 150000th part of an inch. 
 
 It is generally considered that the smallest disc of which tha 
 form can be distinguished by the naked eye, being properly con- 
 trasted with the ground upon which it is seen, is one which would 
 have a visual angle of one minute ; and since a line measuring 
 the 360th part of an inch, placed at ten inches distance, would 
 
 6b 
 
THE MICROSCOPE. 
 
 have tliat visual angle, it would follow that the smallest object 
 of which the form could he rendered distinctly visible by a 
 microscope of a given magnifying power, would be one whose 
 linear dimensions are as many times less than the 360th part of 
 an inch as there are units in the number expressing the magnify- 
 ing power. 
 
 It must not be forgotten, however, in considering such points, 
 that the smallest object whose form can be distinctly seen at a 
 given distance without a glass, depends on many conditions, some 
 connected with the object, and some with the observer, as has been 
 already stated. 
 
 Many persons fall into the error of supposing that the excel- 
 lence of a microscope is to be determined by the greatness of its 
 magnifying power. On the contrary, that instrument must be 
 considered the most efficient which renders the details of an object 
 perceptible with the lowest power. Distinctness of definition, 
 by which is meant, the power of rendering all the minute linea- 
 ments clearly seen, is a quality of greater importance than mere 
 magnifying power. Indeed, without this quality, mere magnify- 
 ing power ceases to have any value, since the object would appear 
 merely as a huge misty silhouette. 
 
 Sufficiency of illumination is another condition which it is 
 difficult to combine with great magnifying power, but which is 
 absolutely necessary for distinct vision. 
 
 If two instruments show the same object with equal distinct- 
 ness of definition and with sufficiency of illumination, one 
 having a higher magnifying power than the other, then it must 
 be admitted that the one which bears, with such conditions, the 
 higher power is the more efficient instrument. 
 
 The mere magnifying power depends on the focal length of 
 the lenses, the illumination on the angle of aperture, and the 
 distinctness of definition on the extent to which those condi- 
 tions have been fulfilled which confer upon the combination of 
 lenses composing the instrument, the qualities of aplanatism and 
 achromatism. 
 
 64 
 
Fig. 35. — Biot's Polariscope. 
 
 THE MICROSCOPE. 
 
 CHAPTEE y. 
 
 MicaopoLAEiscoPE : 69. Polarisation. — 70. Condition of a polarised ray. 
 — 71. Polarisation by double refracting crystals.— 72. Their effect 
 upon rays of light. — 73. The micropolariscope. The siounting op 
 MICROSGOPES : 74. Conditions of efficient mounting, — 75. Frauen- 
 hoffer's mounting. — 76. Methods of varying the direction of the 
 body. Chevalier's universal microscope : 77. Mounting of this 
 instrument. — 78. Method of rendering it vertical.— 79. Method of 
 adapting it to the view of chemical phenomena. — 80. Method of 
 condensing the light upon the object. Ross's improved microscope : 
 81. Useful labours of Mr. Ross. — 82. Details of his improved 
 microscope. 
 
 THE MICRO-POLAEISCOPE. 
 
 69. When a ray of light has been reflected from the surface of 
 a body under certain special conditions, or transmitted through 
 certain transparent crystals, it undergoes a remarkable change in 
 its properties, so that it will no longer be subject to the same 
 effects of reflection, and refraction as before. The effect thus 
 produced upon it, has been called polarisation, and the ray or 
 rays of light thus affected are said to be polarised. 
 Larpner's Museum of Science. f 65 
 
 Kg. 114. 
 
THE MICROSCOPE. 
 
 The name poles is given in physics in general to the sides or 
 ends of any tody which enjoy or have acquired any contrary pro- 
 perties. Thus, the opposite ends or sides of a magnet, have con- 
 trary properties, inasmuch as each attracts what the other repels. 
 The opposite ends of an electric or galvanic arrangement are, for 
 like reasons, denominated poles. 
 
 70. Following the common rule of analogy in nomenclature, a 
 ray of light which has heen submitted to reflection or transmission 
 under the special conditions referred to, has been called polarised 
 light ; inasmuch as it is found that the sides of the ray which 
 lie at right angles to each other, possess contrary physical pro- 
 perties, while those of a ray of common or unpolarised light possess 
 the same physical properties. 
 
 To illustrate the relative physical condition of common light 
 and polarised light, we may compare a ray of common light to a 
 round rod or wire of uniform polish and uniformly white, while 
 a ray of polarised light may be compared to a similar wire, two 
 of whose opposite sides are rough and black, while the other 
 opposite sides at right angles to these are polished and white. 
 Thus, if A B c D, j&g. 33, be a section of the former, the entire 
 circumference A b c d is white and polished, and if a' b' c' d' 
 
 Fig. 34. 
 
 B' 
 
 be a section of the latter, a' b' and c' d' will be white and polished, 
 while B' c' and a' will be black and rough. 
 
 A group of physical properties, very numerous and complicated, 
 characterise the polarised state of light, the discussion and exposi- 
 tion of which, constitute the subject of an extensive and important 
 section of optics. It would be obviously impossible here to convey 
 to the reader any general idea of these ; nevertheless, as an illus- 
 tration of them, one of the most frequent occurrence may be 
 mentioned. If a ray of common light fall upon a smooth and 
 polished surface, it is always reflected according to the well- 
 known laws of reflection, no matter what side of it may be pre- 
 66 
 
 Fig. S3. 
 B 
 
MICRO-POLARISCOPE. 
 
 rented to the reflecting surface. If a polarised ray, however, fall 
 •ut a certain inclination upon the same surface, it will be reflected 
 ^or absorbed according to the side of it which is turned towards 
 the reflecting surface. Thus, if the side A' B' or c' D' be pre- 
 sented towards the reflecting surface, the ray will be reflected a& 
 if it were common light, but if the side b' c' or a' be turned 
 ix)wards the reflecting surface, it will not be reflected at all, but 
 will be, as it were, smothered or extinguished. 
 
 The sides a' b' and c' d', which are opposite to each other, 
 ihave, therefore, a property contrary to that of the sides b' c' and 
 A' D'j so that they are respectively called the poles of the ray, 
 just as the ends of a voltaic circuit having contrary electric pro- 
 perties are called the positive and negative poles of the voltaic 
 battery, and the ends of a magnet are called its boreal and austral, 
 or south and north poles. 
 
 The effects which polarised light produces when it falls upon, 
 €r is transmitted through, various substances, more especially 
 such as are in the state of crystallisation, are of the highest 
 physical importance, being in most cases the indication of mole- 
 cular and other properties, by which optics has been placed in 
 relation with, and has become the handmaid of, almost every 
 •other branch of physical science. 
 
 71. There are various expedients by which a ray of common 
 light can be polarised. It will be polarised if it be reflected at 
 a certain inclination, called from that circumstance the angle of 
 polarisation, from certain surfaces. Each substance has its own 
 angle of polarisation. That of glass, for example, is 35|°. It 
 is also polarised if it pass through certain transparent crystals. 
 Some of these, while they polarise the ray, split it into two, both 
 "being polarised, but in planes at right angles to each other ; that 
 is, for example, the sides a' b' and C d' being white in one, and 
 black in the other. 
 
 The well-known mineral called Iceland spar is an example of 
 this class of crystals. 
 
 Such crystals are called double-refracting crystals, because the 
 two rays into which the ray of common light is split are refracted 
 by the crystal in different directions, and according to different 
 laws. 
 
 When a polarised ray is transmitted through such a crystal, 
 according to certain conditions, it will either pass through it, as 
 it would through any ordinary transparent medium, or will be 
 extinguished by it, according to the side of the ray to which 
 certain faces of the crystal are presented. Such crystal is related 
 to the poles of the ray, therefore, in- the same manner as the 
 reflecting surface already described. 
 
 F 2 67 
 
THE MICROSCOPE. 
 
 72. If either the reflecting surface or the crystal, placed under 
 the necessary conditions, be carried round a polarised ray, a' b' c' d', 
 so as to Toe suooessiyelj presented to all sides of it, the ray will 
 be completely reflected or transmitted when it is presented to a', 
 the middle of the side a' b'. As it is moved from a' towards 6', 
 the quantity of light reflected or transmitted will be less and less, 
 until it comes to h\ when none will be reflected or transmitted, the 
 ray being wholly extinguished. As it is moved from V to c', 
 the light reflected or transmitted, small in quantity at first, will 
 be continually greater and greater until it comes to c' the middle 
 of c' D', when the ray will be wholly reflected or transmitted. 
 As it is moved from c' towards d\ the quantity of light reflected or 
 transmitted is less and less, until arriving at d' the ray is alto- 
 gether extinguished. After passing from d towards a', the light 
 reflected, at first small, is more and more in quantity until it 
 comes in fine to a', when the ray is, as at first, wholly reflected or 
 transmitted. 
 
 73. An instrument adapted to show the efiects of polarised light 
 upon bodies on which it is incident or through which it is trans- 
 mitted, is called a polariscope, fig. 35, p. 65, and a polarising 
 microscope or micko-polariscope, is a microscope by which the 
 observer is enabled to project polarised light upon the objects, and 
 to observe its efiects when transmitted or reflected by them. 
 
 Micro-polariscopes have been constructed in various forms, 
 some depending on polarisation by reflection, and some on polari- 
 sation by transmission. 
 
 One of the most simple and most generally useful, consists of 
 two prisms of Iceland-spar, one of which, p, is placed under the 
 stage, so that the light by which the object is illuminated must 
 previously pass through it, and the other p' is placed in the body 
 of the instrument between the object-glass and the eye-glass, so 
 that before producing the image, the rays must pass through it. 
 
 The light proceeding from P, and projected upon the object, 
 being polarised, and received, after passing through the object- 
 glass, by P', will be wholly or partially transmitted, or altogether 
 extinguished, according to the sides or poles of the ray to which 
 certain faces of the prism are presented. If, therefore, the instru- 
 ment be so mounted that the prism p' can be turned round its 
 axis, its faces can be presented successively to all sides of the 
 rays, so that the light will be in a certain position wholly trans- 
 mitted, and the image will be seen strongly illuminated. When 
 the prism is gradually turned round, the light transmitted will 
 be less and less, until the prism has been turned through a 
 quarter of a revolution, when the light will be wholly 
 extinguished, and the image will disappear. Continuing to turn 
 68 
 
MOUNTING OP MICROSCOPES. 
 
 the prism, the image •will gradually re-appear, at first faintly, 
 and by degrees brighter, until the prism is moved through 
 another quarter of a revolution, when the image will be again 
 seen fully illuminated. Like changes will take place during the 
 other two quarters of a revolution. 
 
 Similar effects will be produced if the prism p' be fixed, and 
 p be turned round its axis. In this case, by moving the polar- 
 ising prism P round its axis, the polarised ray is made to revolve, 
 because the position of its poles a' V c' d' has always a fixed rela- 
 tion to the faces of the p"^ism p. Since, therefore, the polarised 
 ray revolves, it presents successively all its sides to the prism p', 
 by which it is accordingly alternately transmitted, and absorbed 
 wholly or partially in the same manner, exactly as if the ray were 
 fixed, and the prism p' carried round it. 
 
 By the appearance and disappearance of the image correspond- 
 ing with the position of the prism p', the position or direction of 
 the planes of polarisation A' C and b' d' of the polarised ray is 
 known. 
 
 These effects will be produced if the objects through which the 
 light is transmitted or by which it is reflected have themselves 
 no polarising influence. But if they have, various other pheno- 
 mena will ensue, depending on the character and degree of that" 
 influence ; but whatever it be, the state of the light, which pro- 
 ceeding from the object-glass forms the image, will be ascertained 
 by the prism p', which is consequently called the analysing prisma 
 the other p being denominated the polarising prism. 
 
 Various physical characters are thus discovered in the objects 
 submitted to the microscope by determining the optical effects 
 they produce on polarised light, and many striking and beautiful 
 phenomena are developed. 
 
 THE MOUNTING OF MICEOSCOPES. 
 
 74. The methods of mounting microscopes, so as to adapt them 
 to the convenience and the ease of observers, are very various, 
 depending on the purposes to which they are applied, their price, 
 the exigencies of the purchaser, and the skill, taste, and address 
 of the maker. 
 
 The qualities which it is desirable to confer upon the stand and 
 mounting of the instrument are simplicity of construction, easy 
 portability, smoothness and precision in the action of all the 
 moving parts, and such combinations as may cause any tremor 
 imparted to the stand to be distributed equally over every part of 
 the mounting. T}-,ese capital objects are attained very com- 
 pletely in all the mountings of the best makers, British and 
 Foreign. 
 
 69 
 
THE MICROSCOPE. 
 
 The most simple, and consequently tlie cheapest description of 
 mounting, is that in which fewest parts are moveable. The only 
 parts of a compound microscope which are necessarily moveable 
 are those by which the instrument is focussed, and the object 
 illuminated. The most simple mechanical expedient for effecting: 
 the former is a rack and pinion attached either to the body or the 
 stage, and for the latter the suspension of the reflector upon an. 
 horizontal axis, so that it can be inclined at any desired angle ta 
 the axis of the body and the stage. 
 
 Whatever be the form or disposition of the stand, it is- 
 essential that the axis of the object-piece should pass through 
 the centre of the stage, and that the reflector should be so set as 
 to be capable of reflecting light in the direction of this axis. The 
 body is generally a straight tube, the axis of the eye-piece and 
 object-piece being in the same straight line. In the case of 
 instruments mounted after the model of Professor Amici, however, 
 the body consists of a tube having two parts with their axes at 
 right angles, the axis of the object-piece being vertical, while 
 that of the eye-piece is horizontal. In this case, a prism is fixed 
 in the angle of the tube, at an angle of 45" with the axes by 
 which the rays proceeding vertically from the object-piece ar& 
 reflected horizontally to the eye-piece, on the principle already 
 explained (30). 
 
 75. One of the most simple models for the mounting of a com- 
 pound microscope was contrived by Frauenhoffer so early as. 
 1816, long before achromatic lenses were produced. This model, 
 owing to its great simplicity, convenience, and cheapness, is still 
 extensively used for the lower priced instruments, especially by 
 the continental makers. 
 
 The body of the instrument is attached to a vertical •pillar, fig^ 
 36, p. 49, and its axis is permanently vertical. It is focussed by 
 a rack and pinion, worked by a milled head on the right of the 
 observer. The stage is fixed in its position, and placed on the 
 top of a short tube, in the lower part of which the reflector is 
 suspended on an horizontal axis, so that it can be placed at any 
 desired obliquity to the axis of the instrument, and thus can 
 always throw a beam of light upwards to the object. One side 
 of this mirror is concave, and the other plane. 
 
 For the illumination of opaque objects, a lens is attached by 
 a jointed arm to the upper part of the pillar, on which the 
 instrument is supported. 
 
 M. Lerebours, of Paris, makes excellent microscopes on this 
 model, with a triple achromatic object-piece and other accessories,, 
 which he sells at the very moderate price of 90 francs (3/. 12s. )» 
 Several thousands of these have been sold. 
 70 
 
MOUNTING OF MICROSCOPES. 
 
 76. The attitude of an observer stooping the head to view an 
 object in a microscope, whose eye-piece is vertical, is found to be 
 attended with much inconvenience, especially if the observation 
 be long continued. This has constituted the ground of a very 
 general objection to vertical microscopes. Nevertheless there are 
 many cases in which it would be inconvenient to place the stage 
 in an inclined or vertical position, as, for example, when observa- 
 tions are made on liquids. In all such cases the model of 
 Amici's stand presents obvious advantages, the observer looking 
 horizontally, while the axis of the object-piece is vertical,, and 
 consequently the stage horizontal. 
 
 Most of the better class of instruments, however, are so 
 mounted that any direction whatever can be given to the axis of 
 the body. Yarious mechanical expedients are used for accom- 
 plishing this, most of which are analogous to the methods of 
 mounting telescopes. In some, the instrument with its appendages 
 is supported upon two uprights of equal height by means of 
 trunnions, which pass through its centre of gravity, so that it 
 turns upon its supports like a transit instrument, the axis of the 
 body being capable of assuming any inclination to the vertical. 
 The observer, therefore, may at pleasure look obliquely or verti- 
 cally downwards, or obliquely upwards, as may suit his purpose. 
 
 Similar motions are also produced by mounting the instrument 
 upon a single piUar by means either of a cradle-joint, such as is 
 generally used for telescope-stands, or a ball and socket. Stands 
 of this form are attended with the advantages of offering greater 
 facility for moving the instrument horizontally round its axis. 
 
 In the attainment of all these objects, as weU as in the produc- 
 tion of eye-pieces and object-pieces of capital excellence, the 
 leading makers of London, Paris, Berlin, and Yienna, have 
 honourably rivalled each other, and it may be most truly said, to 
 their credit, that if some have excelled others in particular parts 
 of the instrument, there is not one who has not in some way or 
 other contributed by invention or contrivance to the perfection 
 either of the optical or mechanical parts. 
 
 Much however is also due to the eminent philosophers and 
 professors who have more especially devoted their attention to 
 those parts of science in which the microscope is a necessary 
 means of observation, and foremost among these is the patriarch 
 of optical science. Sir David Brewster. It would be difficult to 
 name the part of the instrument, or of its accessories or append- 
 ages, for the improvement of which we are not deeply indebted 
 to this eminent man. Among the more recent philosophers who 
 have contributed to the advancement of micrography, and by 
 whose researches and suggestions the makers have been guided, 
 
 71 
 
THE MICEOSCOPE. 
 
 may "be mentioned Messrs. Goring, Lister, Coddington, Q,uecket, 
 Mandl, Dujardin, Le Baillif, Seguier, De la Rue, and numerous 
 ottiers. 
 
 The eminent makers of the British and Continental capitals are 
 well known. Good instruments of the low-priced sort are made 
 by nearly all the opticians ; hut those who have more especially 
 devoted their labours to the microscope, are Messrs. Ross, Smith 
 and Beck, Powell and Lealand, Pritchard, Yarley, and Pillisdier, 
 in London ; Messrs. Nachet, Charles Chevalier and George 
 Oberhauser, of Paris ; MM. Ploessel and Schieck, of Vienna ; and 
 M. Pistor, of Berlin. 
 
 Without the intention of assigning any relative precedence to 
 these artists, we shall now present a brief description of some of 
 the instruments, according as they are severally mounted by 
 them. 
 
 chevalier's universal microscope. 
 
 77. The mounting of this instrument has always appeared to 
 me to offer as many conveniences and advantages to the observer 
 as can be combined in such an apparatus. 
 
 A mahogany ease a, fig. 37, p. 1, containing a drawer b, in which 
 the instrument and its appendages are packed when out of use, 
 serves as its support. A strong brass pillar, c c, is firmly screwed 
 into the top of the case, and upon this pillar the entire instrument 
 is supported. 
 
 The pillar c c sometimes is made in two lengths, which are 
 screwed one upon the other, by which means the height of the 
 instrument may be varied at pleasure, either one or both lengths 
 being used. 
 
 An arm e c is attached by a joint at E to the summit of the 
 pillar c c, so that it can be moved on the joint E with a hinge 
 motion, and may thus be placed at any angle with the pillar c c. 
 In the figure it is represented at right angles with c c. 
 
 To the middle d of the arm e c, a square brass bar d f g is 
 attached at right angles to e c, so that when E c is at right angles 
 to c c, the bar d f g is parallel to c c. In the face of the bar 
 D F G, which is presented to c c, a rack is cut. 
 
 Two square pieces p and m are fitted to the bar d F g, and are 
 moved at pleasure upwards and downwards upon it by means of 
 pinions, having milled heads o and n. 
 
 To the square piece P is attached the stage z, upon which the 
 object is placed, and maintained in its position by two springs, 
 one of which is shown in the figure. This stage is provided with 
 several adjustments, which have been already explained (31 
 et seq.). It will be sufiicient for the present to observe that it 
 is capable of being moved upwards and downwards with the 
 72 
 
chevalier's mounting. 
 
 square piece p, to which it is attached by turning the milled 
 head o, and that a slower motion, to give more exact adjust- 
 ment, is imparted to it by a fine screw haying a milled head 
 at Q. 
 
 To the square piece m is attached the illuminator h, on one side, 
 
 of which is a concave reflector, and on the other, i, a smaller 
 plane reflector. This illuminator has two motions, a horizontal 
 or lateral one upon a joint at 3i, by which it can be placed at 
 pleasure either vertically under the centre of the stage z, or at a 
 limited distance on one side or other of the vertical through the 
 centre of the stage. The circular illuminator is suspended at two 
 points diametrically opposite in a semicircular piece, and may be 
 placed at any desired inclination to the vertical, and with either 
 reflector upwards by means of the milled head i. 
 
 From the lowest part of the pillar c c a piece projects, having a 
 cavity corresponding with the size and form of the bar d r g, 
 into which that bar enters when it is vertical as represented in the 
 figure, and in which it is held by the pin at g. 
 
 The body of the microscope, as shown in the figure, is rect- 
 angular. The eye-tube t is moved backwards and forwards in the 
 body K by a pinion t: working in a rack. The eye-piece s is 
 inserted in this tube, and the eye is protected from the light by a 
 circular blackened screen, seen edgeways in the figure. The 
 rectangular tube v x is inserted by a bayonet-joint in the remote 
 end of the body e, in which it is capable of being turned, so 
 that the object-tube x shall be horizontal, to enable the observer 
 with greater facility to screw on or to change the object-glasses 
 at Y. 
 
 The body is attached to the bar e c by a joint at c, upon which 
 it can be turned, by which means other positions can be given to 
 the instrument, as will presently be explained. 
 
 An assortment of object-glasses is supplied, which may be 
 screwed at pleasure upon y. They are adapted to each other in 
 sets of three, so that one, two, or three may be attached to y 
 according to the power required. 
 
 In the angle h of the body, a rectangular prism is fixed, by 
 which the rays proceeding upwards from y are reflected horizontally 
 along the axis of K to the eye-piece, on the principle explained 
 in 30. 
 
 Several eye-pieces of different powers are supplied with the 
 instrument. 
 
 The magnifying power may be varied within certain narrow 
 limits by moving the eye-tube in or out by the pinion ir, and at 
 the same time adjusting the focus by the pinions o and Q, which 
 move the stage z. When it is desired to augment the power, the 
 
 73 
 
THE MICROSCOPE. 
 
 tube T is drawn out so as to lengthen the body, and the stage 2 
 is brought nearer to the object-glass y. The effect of this is to 
 increase the dimensions of the optical image produced in the eye- 
 piece by the object and field glasses, as explained in 6. 
 
 If a greater increase of magnifying power be desired, the eye- 
 piece may be withdrawn, and a shorter one substituted for it. 
 
 But these expedients are only useful when the increase of power 
 required is confined within comparatively narrow limits. All 
 greater amplification must be produced by the object-glasses. 
 These, as has been explained, are made in sets of three, having 
 different powers. The lowest power will be obtained by screwing 
 the first lens only of the lowest set upon y ; the next by screwing 
 on the second ; and the next by screwing on the third ; by which 
 the powers of all the three will be combined. 
 
 If it be desired to obtain a still higher power, these lenses 
 being taken off, the first lens of the set next in order is screwed 
 on, then the second, and in fine the third, by which another 
 series of three increasing powers is obtained. 
 
 In this manner, by a suitable assortment of object-glasses and 
 eye-pieces, any desired degree of amplification can be obtained. 
 
 The height of the case a and the length of the pillar c c are 
 so arranged, that when the case is placed upon a table of the 
 usual height, the eye of an observer of average height when seated 
 will be on a level with the eye-piece s. 
 
 When the observer is about to submit an object to examination^ 
 having mounted the instrument, placed it firmly upon a table 
 with an even surface so as to prevent any rocking or instability, 
 and regulated the height of his seat so that his eye shall be at the 
 level of the eye -piece, he selects an eye-piece and object-glasses 
 having a suitable magnifying power, and in doing this it is most 
 important to commence with a low power, to be gradually 
 increased. For this purpose, one object-glass of a set is first 
 screwed on, after which two, and in fine three, are used. 
 
 In this manner a survey is taken of the general outline and 
 larger parts in the first instance, and the more minute parts 
 afterwards. 
 
 78. The most generally convenient position for the instrument 
 is that which is shown in fig. 37. If a vertical position be 
 desired, it may however be easily obtained. For this pur- 
 pose the rectangular piece v is drawn out of the bayonet-joint, 
 and the object- tube is directly inserted in the body, so that its 
 axis shall be horizontal and coincident with that of the body k 
 and the eye-tube t. The body is then turned upon the joint c 
 until it is raised into the vertical position. The relative position 
 which the parts then assume is thai which is shown in fig. 38. 
 74 
 
CHEYALIEH'S MOUNTING. 
 
 79. When chemical phenomena are submitted to microscopic 
 examination, and in general when liquids are observed which are 
 lia ble to evaporation, it is found 
 
 inconvenient to place the stage 
 under the object-glass, inas- 
 much as the vapour proceed- 
 ing from the liquid being 
 more or less condensed upon 
 it, destroys the clearness of 
 the image. 
 
 Acid vapours sometimes rise 
 from the substances under ex- 
 periment, which often tarnish 
 the object-glasses, and almost 
 always corrode the metal of 
 the instrument. 
 
 In such cases, therefore, it 
 is necessary to provide means 
 to place the liquid under ob- 
 servation in a glass capsule 
 (a watch-glass, for example) 
 above the object-glass, which 
 must consequently be directed 
 upwards, the stage supporting 
 the capsule being over it. 
 
 To accomplish this, the rect- 
 angular piece V X is turned 
 within the body upon its bay- 
 onet-joint through half a cir- 
 cumference, so that the object- 
 tube X is presented vertically 
 
 upwards, as shown in fig. 39. The arm e f carrying the stage ly, 
 the diaphragm h to limit the illumination, and the illuminating 
 reflector or lens is then fixed upon the tube x ; these pieces 
 being severally moveable on the bar e / in the manner already 
 described. 
 
 This arrangement is also useful when it is required to observe 
 minute bodies which sink to the bottom of liquids, or animalcules 
 which rarely come near the surface. 
 
 In certain cases, also, the circulation of the blood can only be 
 observed with the instrument in this position. 
 
 80. It is sometimes desirable to direct the instrument hori- 
 zontally towards the stage placed vertically. To accomplish 
 this, it is only necessary, after arranging the instrument as 
 shown in fig. 40, to turn the arm e c round through an angle of 
 
 75 
 
THE MICROSCOPE. 
 
 90*, the pin G being witlidrawn, so as to leave the bar d p a 
 with the stage and its appendages free to turn on the joint e with 
 the arm e c. The body e and the bar d p g will then be brought 
 
 Fifr. 39. 
 
 into the horizontal position. The stage will then be vertical, and 
 the object will be held in its position by the springs. 
 
 The illumination of the object may be produced either by the 
 reflector or lens in the manner already described ; or, if they are 
 removed from the bar D r g, the stage may be presented directly 
 to the light of the sun, the clouds, or a candle or lamp. 
 
 In some cases, however, when it is necessary to obtain a more 
 intense illumination, an apparatus represented at s s' is employed, 
 consisting of two convex lenses placed in the ends of a conical 
 tube which slides upon the bar, by means of a square piece at the 
 end of the arm t. 
 76 
 
CHEVALIER'S MOUNTING. 
 
 Besides the several motions above described, the body of the 
 instrument has motion in an horizontal plane round the piece a, 
 
 Fijf. 40. 
 
 fig. 37, as a centre. This motion is very convenient when the 
 instrument is used in the positions shown in figs. 37, 38, and 39, 
 
 77 
 
THE MICROSCOPE. 
 
 for the purpose of clianging the angles. In general, and more 
 especially when high powers are used, the object-glasses are so 
 close to the stage, that they cannot be conveniently unscrewed 
 and changed without either removing the object- tube from the 
 stage, or the latter from the former. If, however, the body be 
 turned horizontally upon the centre a through a few degrees, the 
 object-tube will be removed from over the stage, and the lenses 
 can easily be changed. 
 
 This method may also be practised in the positions shown in 
 figs. 38 and 40, but it is more convenient to turn the rectangular 
 piece YX upon the bayonet-joint, as directed above. 
 
 Another advantage which attends this horizontal motion of the 
 body round the centre «, is, that it enables the observer to direct 
 the object-glass successively on different points of an object, the 
 whole of which is not included in the field of view. This, how- 
 ever, can only be practised where low magnifiers are used. 
 
 To place this microscope in any desired inclined position, it is 
 only necessary to place the body, as represented in fig. 38, and 
 then taking out the pin g, fig. 37, to turn the bar D F G together 
 with the body k into the desired inclination. 
 
 boss's improved miceoscope. 
 
 81. Mr. Ross holds a place in the foremost rank of philosophical 
 artists, and deservedly enjoys an European celebrity. 
 
 To his labours, perseverance, and genius, much of the perfection 
 attained in the construction of object-lenses is due. The 
 adjusting object-piece, already described, is one of his recent 
 inventions (19). 
 
 In the progressive improvement which the microscope has 
 undergone in his hands, the stand and the mounting, with the 
 provisions for the arrangement of the accessories, have of course 
 been more or less modified from time to time, and are at present 
 varied according to the price of the instrument, and the purposes 
 of the observer. 
 
 82. We shall here give a short description of the most recent 
 form given by him to his best instruments. 
 
 Upon a tripod, 1, 1, fig. 41, are erected two upright pieces, 2, 2, 
 strengthened by inside buttresses, 3. These uprights support an 
 horizontal axis, 4, which passes nearly through the centre of gravity 
 of the instrument, and upon which it turns, so that the axis of the 
 body may be placed in any direction, vertical, horizontal, or 
 oblique. The rectangular bar, 5, having a rack at the back, is 
 moved in the box, 6, by the pinion, 7. The body, 8, is inserted 
 in a ring at the end of the arm, 9, which latter is fixed upon a 
 pin at the end of the rod, 5, upon which it turns, so as to remove 
 78 
 
THE MICROSCOPE. 
 
 at pleasure tlie object-piece from over the stage, to change or clean 
 the lenses. The arm, 9, can be fixed in its position by the pin^ 
 whose milled head is 10, 
 
 The instrument is focussed first by moving the body to and from 
 the stage by means of the pinion, 7, and rack, 5, the adjustment 
 being completed by a much slower motion imparted to the body 
 by the milled head, 1 1 , which is connected with a screw and lever, 
 by one revolution of which the body is moved through the 
 300th part of an inch. An elastic play is allowed to the body, so 
 as to guard against injury by the accidental contact of the object- 
 piece with the slide. 
 
 The usual rectangular motions are imparted to the stage, 12, 
 through the extent of an inch, by the milled heads, 13, which 
 act on pinions, by which the racks are driven which carry the 
 stage right and left, and backward and forward. The illumi- 
 nating mirror, 14, is supported in the usual way, so as to be placed 
 at any desired angle with the axis of the instrument. Below the 
 stage is fixed an arm, 15, capable of being moved up and down 
 by rack and pinion. This arm supports a tube, 16, intended to 
 receive apparatus to modify the light transmitted by 14 to the 
 object. Various apparatus for condensing and otherwise modify- 
 ing the illumination are provided, which fit into this tube, 16. 
 A motion of revolution round its axis is given to this tube by the 
 milled head, 17. By these means, the effect of oblique light can 
 be shown on all parts of the object. A condenser, 18, invented 
 by Mr. Gillet, of a peculiar construction, provided with a series 
 of diaphragms formed in a conical ring, is inserted beneath the 
 stage. 
 
 Polarising apparatus, and other appendages, can also be attached 
 to the secondary stage. 
 
 80 
 
Fig. 45.— Nachet's Triple Microsoopb. 
 
 THE MICROSCOPE. 
 
 CHAPTEE YI. 
 
 83. His object-glasses. Messrs. Smith and Beck's micuoscopb : 84. Then- 
 largest and most efficient instrument, — 85. Their smaller microscope. 
 — 86. Their object-glasses. — 87. Varley's microscope. M. Nachet's 
 MICROSCOPE : 88. Their adaptation to medical and chemical purposes. 
 ■ — 89. Multiple microscopes. — 90. Double microscope. — 91. Binocular 
 microscope. — 92. Triple and quadruple microscopes. 
 
 83. With his largest and best instruments, Mr. Eoss supplies 
 four eye-glasses and eiglit object-glasses, by which, thirty- two 
 varieties of power and illumination may be obtained. The object- 
 glasses vary from two inches to a 12th of an inch in focal 
 length, and from 12° to 170° in angular aperture. The following 
 Lardner's Museum of Science. a 81 
 
 No. 116. 
 
THE MICROSCOPE. 
 
 is a tabulated statement of the powers resulting from these com- 
 binations, the four eye-glasses being designated in the order of 
 their powers, by the letters A, b, c, and d. The prices of the 
 object-glasses severally are given in the last column of the table, 
 and the slightest reference to them will explain the general desire 
 of microscopists to diminish expense, by varying their powers, by 
 the expedient of separating the lenses which enter into the com- 
 position of the object-pieces. 
 
 Achromatic Object-glasses for Microscopes. 
 
 Object-glasses. 
 
 Angular 
 Aperture. 
 
 Magnifying Powers with the 
 various Eye -glasses. 
 
 Price. 
 
 
 
 A. 
 
 B. 
 
 c. 
 
 D. 
 
 £ s. d. 
 
 % inches . . 
 I . . 
 I . . 
 
 4 „ . . 
 
 1 
 
 s >> • • 
 
 1 
 
 T2 >> • • 
 
 12 degrees. 
 15 „ . 
 
 22 ,, 
 
 65 . 
 
 85 * „ . 
 ,» . 
 150 „ . 
 170 „ . 
 
 20 
 60 
 
 >> 
 100 
 220 
 320 
 420 
 650 
 
 30 
 80 
 
 130 
 
 350 
 510 
 670 
 900 
 
 40 
 
 100 
 >> 
 
 180 
 
 500 
 700 
 900 
 1250 
 
 60 
 120 
 »> 
 
 220 
 
 620 
 
 910 
 1200 
 2000 
 
 1 
 
 300 
 200 
 3 10 0 
 5 5 <3 
 5 5 <5 
 10 0 0 
 12 0 0 
 x8 0 0 
 
 When angular apertures, so extreme as those indicated in the 
 preceding table, are attempted, it is necessary that the object- 
 lens presented to the pencil diverging from the object, shall be 
 of the meniscus form, the concave side being turned towards the 
 objeet, for the reasons explained in 19. 
 
 Besides the larger class of instruments above described, Mr. 
 Ross constructs microscopes in a variety of other forms, which 
 are placed within the reach of those who do not find it conve- 
 nient to incur the expense of the larger instrument. 
 
 MESSES. SMITH AND BECKYS MICEOSCOPE. 
 
 84. The largest and most efficient class of instruments con- 
 structed by these artists, do not differ much in their mounting 
 from those of Mr. Ross above described. Like the latter, they 
 are supported by a horizontal axis, between two strong vertical 
 pillars, screwed into a tripod base. The instrument with its 
 d,ppendages, turning on the horizontal axis, can thus be placed at 
 any obliquity whatever with the vertical. The coarse adjust- 
 taent of this microscope is made by a rack and pinion, by which 
 82 
 
KOSS — SMITH AND BECK. 
 
 the entire body is moved to and from the stage. The object- 
 piece is set in a tube, which moves within the principal tube of 
 the body, the motion being imparted to it by a fine screw with a 
 milled head, which constitutes the fine adjustment. Two dif- 
 ferent kinds of stage are supplied, one called the lever stage, 
 consisting of three plates of brass, the lowest of which is fixed, 
 and the other two provided with guides and slides, and a lever by 
 which they may be moved, together or separately, in directions at 
 right angles to each other ; the other form of stage also has two 
 motions at right angles to each other, one produced by rack and 
 pinion, and the other by a screw whose axis is carried across the 
 stage, and is turned by the left hand, while the rack and pinion 
 is turned by the right hand. 
 
 85. Messrs. Smith and Beck also construct other forms of 
 microscope, which, though perfectly efficient, are cheaper and more 
 simple ; one of these is represented in fig. 42, p. 17. It is mounted 
 upon a vertical pillar, supported on a tripod t ; the body of the 
 microscope plays upon a cradle joint, to which the bent arm 
 u IT is attached ; the body of the instrument is moved by a rack 
 and pinion in a triangular groove formed in the upper part of 
 this arm; the coarse adjustment is made by the milled heads 
 which move the entire body to and from the stage. In the 
 lower end of the body, a tube is inserted, from which an arm 
 projects, in which a fine screw plays, which is connected with 
 another arm attached to the body of the instrument : by turning 
 the milled head, a slow motion is therefore imparted to the 
 tube thus inserted in the lower extremity of the body. In the 
 end of this tube the object-piece is set, so that the fine adjust- 
 ment is made by this screw. 
 
 To the lower end of the bent arm u tj^ the stage and its 
 appendages are attached; two motions at right angles to each 
 other are imparted to the stage, by milled heads ; the reflector 
 is mounted in the usual way, and provisions are made under the 
 stage, by which achromatic condensers, polarisers, and other 
 apparatus can be applied ; the disc of diaphragms is shown at L ; 
 it is mounted on a short piece of tube, in which polarising and 
 other apparatus may be inserted. 
 
 86. Messrs. Smith and Beck supply with their best microscopes 
 three eye-pieces and five object-pieces, the powers of which, as 
 well as their angles of aperture, are indicated with their prices in 
 the annexed table. 
 
 » 
 
 o 2 HZ 
 
THE MICROSCOPE. 
 
 Achromatic Object-glasses for the Microscope. 
 
 Focal 
 length. 
 
 Linear Magnifying 
 
 Powe: 
 
 With 
 No.l. 
 
 f near] 
 
 Eye-p 
 No. 2. 
 
 y.* 
 
 eces. 
 No.3. 
 
 Angle of 
 aperture 
 about 
 
 Price. 
 
 Lieoer- 
 kubn 
 addi- 
 tional. 
 
 inch. 
 
 Draw-tube closed 
 Add for each inch 
 oftube drawn out 
 
 20 
 4 
 
 45 
 6 
 
 80 
 8 
 
 13 degs. 
 
 £ s. d. 
 300 
 
 s. 
 
 15 
 
 1 inch 
 
 Tube closed . . 
 Add for each inch 
 of tube . . . 
 
 60 
 7 
 
 105 
 12 
 
 180 
 20 
 
 27 degs. 
 
 3 3 0 
 
 II 
 
 Y^inch 
 
 Ditto 
 Ditto 
 
 Tube closed . . 
 Add for each inch 
 of tube . . . 
 
 Ditto . . . 
 Ditto . . . 
 
 120 
 
 12 
 
 do. 
 do. 
 
 210 
 
 20 
 
 do. 
 do. 
 
 350 
 
 35 
 
 do. 
 do. 
 
 55 degs. 
 
 65 degs. 
 75 degs. 
 
 5 5 0 
 
 660 
 770 
 
 10 
 
 10 
 10 
 
 \ inch 
 Ditto 
 
 Tube closed . . 
 Add for each inch 
 of tube . . . 
 
 Ditto , . . 
 
 240 
 do. 
 
 430 
 
 45 
 do. 
 
 720 
 80 
 do. 
 
 85 degs. 
 100 degs. 
 
 660 
 770 
 
 
 \ inch 
 Ditto 
 
 Tube closed . 
 Add for each inch 
 oftube , . . 
 
 Ditto . . . 
 
 450 
 
 40 
 
 do. 
 
 760 
 60 
 do. 
 
 1300 
 
 "5 
 do. 
 
 100 degs. 
 120 degs. 
 
 880 
 10 10 0 
 
 
 * With the I inch object-glass and the erecting-glasses, emplo3dng eye-pieces 
 Nos. 1 and 2, the magnifying power will range from 5 to 150. 
 
 Among the accessories of the microscope due to Messrs. Smith 
 and Beck, we must not omit to mention the microscope-table, 
 contrived to facilitate the observations of several persons directed 
 to the same object with the same microscope. Every one who 
 has used this instrument is aware how fatiguing it is to several 
 persons to succeed one another in observing with the same instru- 
 ment. They are obliged constantly to shift their position, and 
 consequently to make their observation standing. The micro- 
 scope-table, if it do not entirely remove this inconvenience, 
 greatly diminishes it. It is a circular table, firmly supported on a 
 pillar and claw, capable of being turned with a smooth motion 
 round its centre in its own plane. The observers sitting round 
 it, the microscope is moved successively to the position occupied 
 by each of them by merely turning the table. The best sort of 
 84 
 
VARLEY— NACHET. 
 
 these tables are made with a plate-glass top, and surrounded by 
 drawers, in which the apparatus can be conveniently assorted. 
 
 ME. YARLEX'S MICEOSCOPE. 
 
 87. This artist has constructed instruments with provisions 
 similar to those already described ; they are somewhat different in 
 their form and details. He has, however, recently introduced a 
 microscope, which claims the advantage of enabling the observer to 
 examine living objects, such as animalcules, notwithstanding the 
 inconvenience arising from their restless mobility, causing them 
 continually to escape from the field of view. The stage motion 
 with its appendages, contrived by Mr. Yarley, enables the 
 observer, without difficulty, to pursue the object. 
 
 He has also contrived a phial-microscope, by which aquatic 
 plants and animals can be conveniently observed. 
 
 M. nachet's miceoscopes. 
 
 88. M. ISTachet, of Paris, has acquired an European celebrity for 
 the excellence of his instruments, and for the various inventions 
 and improvements in their construction, by which he has extended 
 their utility. He has constructed instruments in various forms, 
 according to the uses to which they are to be applied and their 
 price. For medical and chemical purposes, the body of the 
 microscope slides in a vertical tube, the coarse adjustment being 
 made by a rack and pinion, and the fine by a screw. The stage 
 is firmly fixed under the object-piece, at the top of a hollow 
 cylinder, within which the illuminating apparatus and other 
 appendages are included. 
 
 89. One of the most recent novelties due to this eminent artist, 
 is a form of microscope by which two or more observers may, at 
 the same time, view the same object, thus conferring upon the 
 common microscope a part of the advantages which attend the 
 solar microscope. This is accomplished by connecting two or 
 more tubes, each containing its own eye-piece, with a single tube 
 containing an object-piece ; it has been already shown that the 
 axis of the tube containing the eye-piece may be placed at any 
 desired inclination, with that which contains the object-piece, by 
 placing in the angle formed by the two tubes, a reflector, or 
 reflecting prism, in such a position, that the pencils of rays pro- 
 ceeding from the object-piece shall be reflected to the eye-piece, 
 without otherwise deranging them. It is evident, therefore, that 
 if the rays proceeding from the object-piece could be at the 
 same time received by two or more reflectors, so placed as to 
 reflect them in two or more directions, they might be transmitted 
 along two or more tubes in these directions to two or more eye- 
 pieces, through which the same object might thus be viewed at 
 
THE MICROSCOPE. 
 
 the same time, and tlirough the same object-piece by two or more 
 different observers. 
 
 Such is the principle upon which the multocular microscope 
 of M. Nachet is based. 
 
 90. A double instrument of this description is shown in fig. 43, 
 where a is the object-piece directed vertically downwards on the 
 stage ; above it is a case, containing a triangular prism which is 
 so formed that the light reflected from its left side shall pass 
 along the axis of the right-hand tube, and that reflected from 
 its right side along the axis of the left-hand tube. Observers 
 looking into eye-glasses set in these tubes, would therefore both 
 see the same object in precisely the same manner. 
 
 It may perhaps be objected, that the focus which would suit the 
 eye of one observer, would not suit the other ; the difference, 
 however, between the focal adjustments of different eyes is always 
 so inconsiderable, that it can be equalised by a small motion 
 given to the tubes carrying the eye-pieces. 
 
 Microscopes, as they are usually mounted, reverse the objects, 
 the top appearing at the bottom, the right at the left, and vice 
 versa. This being found inconvenient in instruments used for 
 dissection, where the motion of the hand and the scalpel of the 
 operator would be reversed, expedients are provided by which the 
 
 image is redressed, and the object viewed m its natural position. 
 This is accomplished in the microscope represented in flg. 43, by 
 
 m 
 
nachet's microscopes. 
 
 Fig. 44. 
 
 two prisms fixed at b b' in the tubes, which are placed at right 
 angles to the lower prism a ; by this 
 second reflection, the reversed image of 
 the first reflection, being again reversed, 
 is made to correspond with the natural 
 position of the object. 
 
 91. An interesting variety of this fornr 
 of instrument, which m^ay be called a 
 BiJrocuLAE, MICROSCOPE, is shown in 
 fig. 44. In this case the two tubes, b c 
 and B* c', containing the two eye-pieces, 
 are placed parallel to each other, the 
 distance between them bein^ regulated 
 by the screws v v ; if this distance he 
 so adjusted as to correspond with theB- 
 distance between eyes of the same 
 individual, the microscope may be used/ 
 with both eyes, in the same manner as 
 a double opera-glass. This has the 
 advantage of giving a stronger ap- 
 pearance of relief to the objects viewed, 
 which is especially desirable for a certain class of objects, sucii as 
 crystals, 
 
 92. A triple microscope, upon the principle above described, is 
 shown in fig. 45, p. 61, where a is the object-piece, b the multiple 
 prism, and c, c' and c" the three eye-tubes. 
 
 A similar instrument, with four eye-tubes, including figures to 
 illustrate the mode of observing with it, is shown in fig. 46, p. 33. 
 
 One of the advantages of this class of instruments is, that a 
 professor and one or more of his pupils may view the process of a 
 microscopic dissection which with a common microscope would be 
 impossible, and to which the solar microscope would be inap- 
 plicable. Microscopic dissections, in general, can only be exhibited 
 to those who do not execute them, by their ultimate results. Any 
 phenomena which are developed in their progress, can only be 
 made known to others by description ; and it is not necessary to 
 say, how imperfect such a mode of communication must be, com- 
 pared with direct observation. 
 
 187 
 
Tig. 5.— MAGNIFIED VIEW 01" THE LTTRCO OR GLUTTOH. 
 
 MICROSCOPIC OBJECTS. 
 
 ♦ 
 
 1. Microscoxnc objects. — 2. The dragon-fly and its larvse. — 3. The satyr. 
 — 4. The linceus sphericus. — 5. Th* Inrco, or glutton. — 6. The 
 ■water-fly. 
 
 1. HAYTPfG in the preceding Tract explained tlie structure, 
 application, and use of the microscope in the various forms which 
 have been given to that instrument, we shall here briefly notice a 
 few remarkable microscopic objects, selected chiefly from the 
 Microscopic Cabinet of Mr. Pritchard, illustrated with magnified 
 drawings by the late Br. Goring. 
 
 2. The family libelluMse includes an extensive and beautiful 
 group of large insects not sensibly differing in their external form 
 from the ant-lion, already noticed.* 
 
 * Instinct and Intelligence, p. 119. 
 
 88 
 
DEAGON-FLIES AND THEIE LARV^. 
 
 These are popularly known hj the names of horse-stingers 
 and dragon-flies. The former name is founded on a vulgar 
 error, since the animal has no sting. The illusion implied by the 
 latter is, however, more correct, since the insects, both in their 
 appearance and voracious habits, are certainly more entitled to the 
 name of dragons than that of demoiselles, or lady-flies, by which 
 thev are commonly known in France. 
 
 Fig. 1. 
 
 The beautiful appearance of these insects on the wing, their 
 varied colours, the gauze-like structure of their wings, and the 
 rapidity of their flight, must have attracted general attention. 
 In hot summer days, they may be seen darting backwards and 
 forwards in the air over standing pools, which supply them 
 abundantly with the insects on which they feed. Their colours 
 are subject to much diversity, the males having an abdomen of 
 leadish blue, while that of the females is a yellowish brown. In 
 some species, the males have a rich bright blue colour, with black 
 wings, while the females are distinguished by a fine green, with 
 colourless wings. 
 
 After impregnation, the female hovers over the surface of the 
 water until she selects a place for the deposition of her eggs, 
 which she deposits one by one in the water, beating the surface 
 with her tail while she lays them, until at length they are col- 
 lected into a mass resembling a bunch of grapes. 
 
 The larvse on issuing from the egg are so minute as to be 
 scarcely perceptible to the naked eye. In some days, however, 
 they attain the length of the tenth of an inch, and cast their skin 
 f "r the first time. To the naked eye they appear in this state 
 like black spots, to which a tail is attached. When well fed they 
 grow rapidly ; and when they have attained the length of about 
 a quarter of an inch, they begin to display their characteristic 
 courage and ferocity, attacking, with open mouth, creatures ten 
 times their own buUi ; and, when pressed by hunger, devouring 
 each other, 
 
 -89 
 
MICROSCOPIC OBJECTS. 
 The magnified drawing of this larva, from which fig. 2 was 
 
 taken, was made by Dr. Goring, and published with a description 
 90 
 
SATYR. 
 
 by Mr. Pritcliard in tlie Microscopic Cabinet. The real length of 
 the creature, measured from the extremity of the antennae tc 
 that of the tail, was eight-tenths of an inch. It is repre- 
 sented in the figure, as seen in profile, the breadth of the head 
 and other parts being necessarily foreshortened. 
 
 A system of trachese, with numerous ramifications, passes along 
 each side of the body from the head to the tail, one of which is 
 seen in the figure. These respiratory apparatus ramify in a 
 beautiful manner in the triple branches of the tail, each of which 
 receives a branch from each trachea. 
 
 During its growth the larva casts its skin several times, and 
 the skin which it thus throws oflf, being translucent, is an inter- 
 esting and beautiful microscopic object. 
 
 The eyes as well in the larva as in the perfect insect are very 
 salient, and from their magnitude and structure form interesting 
 microscopic objects. Like those of some other insects described 
 in a former Tract,* they consist of a multitude of distinct organs 
 of vision, each of which is an hexagonal lens. It was observed 
 by Latreille, that their number increased in proportion to the 
 voracity of the insect. Leuwenhoeck counted 12000 in a single 
 insect. Each hexagon is a convergent lens, which may be 
 converted into a microscope. Each of these lenses is found 
 to produce an inverted image of an object to which it is 
 presented. 
 
 3. The object shown in fig. 3, engraved from a drawing by Dr. 
 Goring, and described in the 
 Microscopic Cabinet by Mr. 
 Pritchard, belongs to the claiil 
 of animalcules denominated 
 by Miiller monoculi, from the 
 circmnstance of their having 
 a single organ of vision, o, 
 placed in the centre of the 
 front of the head. This 
 specimen is called the satyr, 
 and is ' the amymone satyr of 
 Miiller. The figure represents 
 a magnified view of the full- 
 grown insect, seen at the in- 
 ferior surface of its body as 
 it presents itself to the observer, attached to the inner surface of a 
 vase of water in which it moves. The real length of the animalcule 
 here represented was the 120th of an inch. When they are 
 
 * ''Microscopic Drawing and Engraving," p. 50. 
 
 HI 
 
MICROSCOPIC OBJECTS. 
 
 young they are mucli smaller, and being then perfectly translucent, 
 are highly interesting microscopic objects. They are found in 
 abundance in the months of March and April, at the surface of 
 shallow pools of clear water which contain aquatic plants. 
 
 The -back of this animalcule is protected by a tender and 
 transparent shell, the belly being naked and membranous. Seen 
 in profile it resembles a tortoise, but, as shown in the figure, it has 
 the form of a horse- shoe. It has four feet, and two antennae 
 attached to the inferior part of the body, and radiating from a 
 common centre. Placed in the middle of the head, between the 
 two antennae, 6, are the mouth and the single eye, a, the latter 
 being black, and set in a square orbit of a deep crimson colour. 
 Each of the antennae has four articulations, and is furnished with 
 bristles at its extremity. The feet, c c, are divided at the second 
 joint, and terminate in strong pincers. The peristaltic motion of 
 the alimentary canal can be distinctly perceived with the micro- 
 scope, by observing the dark lines which run along the body of 
 the animalcule. On each side of this canal are placed the 
 ovaries, which, when they are fully developed, are distin- 
 guished by their dark colour. The satyr swims by sudden 
 impulses, moving the feet rapidly, and sometimes appears to 
 slide along the internal surface of the vase. 
 
 4. The animalcule represented in fig. 4, and reproduced from a 
 
 drawing by Dr. Goring, 
 is the linceus sphericus 
 of Miiller, miscalled mon- 
 oculus minutus by Lin- 
 naeus, since it has two 
 eyes sufficiently apparent. 
 The figure is reproduced 
 from the Microscopic 
 Cabinet of Mr. Pritchard, 
 where the animalcule is 
 described. 
 
 The shell or cuirass, 
 which is quite trans- 
 lucent, consists of a single 
 piece, without any per- 
 ceptible articulation. It 
 possesses, however, suf- 
 ficient elasticity to allow the animal to open it at will, after 
 the manner of a common mussel. The two edges of the 
 opening are seen in the figure at a, the figure being understood 
 to present a profile of the object. The two eyes, o, have 
 different magnitudes, and their black colour presents a striking 
 93 
 
LINCEUS — CYCLOPS. 
 
 contrast with the- surrounding parts. They are encased in ttie 
 shell by which they are protected. The beak, 6, is pointed, and 
 participates in the general convexity of the shell. Under it is 
 placed a second beak-like projection, somewhat shorter, and 
 having three coarse hairs at its extremity, which probably serve 
 the purpose of palpi or feelers. Below this are placed the 
 two antennae, c, each of which is terminated by similar but 
 longer hairs. The false feet or branchiae, which are four in 
 number and ranged along the edge, of the shell, are covered 
 with hairs, and terminate like the antennae ; by their action a 
 rotatory motion is imparted to the animalcule, which is accele- 
 rated by the action of the projecting part, against the water. 
 This part is ciliated on its posterior edge, and armed at its 
 extremity .with strong claws. The ovaries, which appear at c, 
 have a greenish-blue colour, and the form of a mulberry. The 
 convolutions of the alimentary canal with the fdod contained in 
 it are visible with the microscope from one extremity to the 
 other. 
 
 But the most remarkable organ is a small oval body placed 
 behind the head and shown in the upper part of the figure. This 
 body has a rapid motion of pulsation. 
 
 5. These creatures feed upon animalcules, and in their turn 
 become themselves the prey of aquatic larvae and coleoptera, such as 
 the water-beetles. They are the especial food of the lurco, or 
 glutton (the larva of the naid), a magnified view of which is shown 
 in fig. 5, with several lincei, c, visible within it. The young ones are 
 seen playing around the mother, and on the approach of an enemy 
 they rush for protection under her cuirass, which she immediately 
 closes upon them. 
 
 6. The crustaceous animalcule represented in b, fig. 1, in its 
 natural size, and in a, fig. 2, magnified, is the four-horned cyclops, 
 or little water-fly ; the cyclops quadricornis of Miiller, the mon- 
 oculus quadricornis of Linnaeus, and the pediculus aquations, or 
 water-louse, of Baker. The figure was drawn by Dr. Goring, and 
 described by Mr. Pritchard in the Microscopic Cabinet. 
 
 This little animal is found at all seasons in water, but more 
 especially in the months of July and August, when it may be 
 easily taken by a net at the depth of about an inch below the 
 surface. 
 
 The body is covered with scales, which have a vertical and 
 lateral motion. Their edges do not meet under the insect, but 
 leave a space for the insertion of the organs of respiration, a. 
 The beak is short and pointed, and is a mere prolongation of the 
 first segment of the body. A little above it is inserted in the 
 cuirass a single eye of a crimson colour, so dark as to approach 
 
 93 
 
MICROSCOPIC OBJECTS. 
 
 nearly to black. On eacli side of the eye are inserted the antennae, 
 of which there are two pair, the superior being longer than the 
 inferior. They are composed of numerous articulations, from each 
 of which issue two or several hairs. In some species the sexes are 
 distinguished by the form of these appendages, being straight and 
 thicker, with an enlargement towards the middle of their length, 
 in the male, as shown in fig. 4. 
 
 These insects move by sudden jumps or plunges, but sometimes 
 creep along the twigs of plants, in which movements they are 
 
 A 
 
 aided by their feet or branchiae. These members are in almost 
 incessant motion, a circumstance which renders the observation of 
 their precise form in the living animal difficult. One of them is 
 represented as seen under a higher magnifying power in A, fig. 3 ; 
 they are generally transparent, but sometimes have a greenish- 
 blue colour. 
 94 
 
CYCLOPS. 
 
 The ovaries consist of two sacs, which have the appearance of 
 bunches of grapes attached to either side of the posterior extremitr 
 of the body, as shown in A, fig. 2. The eggs are globular, and are 
 enclosed in a transparent membrane. The centre of each egg has 
 an opaque colour, some being green and others red. Their number 
 increases with the age of the female, and when they have attained 
 a sufficient maturity the embryo of the future animal may be 
 seen within them with a magnifier. Mr. Pritchard has distinctly 
 seen these with a single lens with a focal length of about the 25th 
 of an inch. At the extremity of the alimentary canal the tail 
 
 B 
 
 divides into two portions, whose extremities are fringed with 
 bristles, which present the appearance of splendid plumes. 
 
 The alimentary canal and its peristaltic movements are dis- 
 tinctly visible in specimens which are only slightly coloured. 
 Above this canal two others can be observed, through which the 
 eggs are projected to the ovaries at each side of the. tail 
 
 95 
 
MICROSCOPIC OBJECTS. 
 
 The colours of the coat of these insects vary in different indivi- 
 duals, as well as the colours of their ovaries, some being of a 
 greenish-blue, and others red with green ovaries. 
 
 Another variety of this, called by Miiller the cyclops minutus, 
 or little Cyclops, and popularly the jumper, is shown in b, fig. 5, 
 as drawn by Dr. Goring, the animalcule being in a bent position, 
 one of its characteristic attitudes. The real length of this 
 specimen was about the 250th of an inch. 
 
 The structure of the coat, or cuirass, is similar to that of the 
 animalcule represented in a, fig. 2, but it has a greater number of 
 segments and a more graceful outline. The single eye is encrusted 
 in the shell. The antennae have not as many articulations as 
 those of fig. 2, and the inferior pair of palpi is more plumed at 
 the extremities. The most remarkable distinction between the 
 two species is, that the latter is much smaller and supplied with 
 only a single gill or respiratory organ under its beak. It has ten 
 feet, and the female carries only a single bunch of eggs under the 
 ' abdomen. In some individuals the respiratory organ observed by 
 Mr. Pritchard has the form represented in b, fig. 6. 
 
Fig. 1.— The Termes Embia. 
 I 
 
 I'ig. 2.— The Termes Fatalis, or Bellioosus, witli wings folded. 
 
 Fig. 3. — Termes Fatalis, or Bellicosus, with wings expanded. Fig. 4.— The King. 
 
 THE WHITE ANTS. 
 
 THEIR MAOTEES AND HABITS. 
 
 CHAPTEE 1. 
 
 1. Their classification. — 2. Their mischievous habits. — 3. The constitu- 
 tion of their societies. — 4. Chiefly confined to the tropics. — 5. 
 Figures of the king and queen. — 6. Of the workers and soldiers. — 
 7. Treatment of the king and queen.' — 8. Habits of the workers.— 
 9. Of the soldiers.— 10. The nymphs. — 11. Physiological characters. 
 — 12. First establishment of a colony. — 13. Their use as food 
 and medicine. — 14. The election of the king and queen. — 15. 
 Their subsequent treatment. — 16. The impregnation of the queen. 
 — 17. Figure of the pregnant, queen. — 18. Her vast fertility. — 
 19. Care bestowed upon the eggs by the workers. — 20. The royal 
 body-guard. — 21. The habitation of the colony. — 22. Process of its 
 construction. — 23. Its cjiambers, corridors, and approaches. — 24. 
 
 LiRDNER's Museum OP Science. h 97 
 
 No. 106. 
 
THE WHITE ANTS. 
 
 Vertical section, showing its internal arrangement. — 25. View of 
 these liabitations. — 26. Contrivances in their construction. — 27. Use 
 made of them by the wild cattle. — 28. Used to obtain views to seaward. 
 — 29. Use of domic summit for the preservation of the colony. — 
 30. Position, form, and arrangement of the royal chamber — its 
 gradual enlargement for the accommodation of the sovereigns. — 31. 
 Its doors. — 32, The surrounding antechambers and corridors. — 33. 
 The nurseries. — 34, Their walls and partitions. — 35. Their position 
 varied according to the exigencies of the colony, — 36. The continual 
 repair and alterations of the habitation. — 37. Peculiar mould which 
 coats the walls, — 38. The store-rooms for provisions — the inclined 
 paths which approach them — the curious gothic arches which sur- 
 mount the apartments, — 39. The subterranean passages, galleries, 
 and tunnels. — 40. The covei'ed ways by which the habitation is 
 approached. — 41. The gradients or slopes which regulate these covered 
 ways. — 42. The bridges by which they pass from one part of the 
 habitation to another. — 43. Reflections on these wonderful works. — 
 
 44. The tenderness of their bodies render covered ways necessary. — 
 
 45. When forced to travel above ground they make a covered way — 
 if it be accidentally destroyed they will reconstruct it. 
 
 1. Of all the classes of insects which live in organised societies, 
 the most remarkable after the bee are the family Termitinse, popu- 
 larly known under the name of white ants, though they have 
 little in common with the ant, except their social character and 
 habits. 
 
 Much discordance has prevailed among naturalists respecting 
 their history and classification. They were assigned by Linnaeus to 
 the order Aptera, or wingless insects. More exact observation 
 has, however, proved this to be erroneous ; since, in the perfect 
 state, they possess membranous wings like those of the dragon-fly, 
 which being four in number, they have been more correctly 
 assigned to the order Neuroptera. Kirby regards them as forming, 
 together with the ants, a link between the orders Neuroptera 
 and Hymenoptera, being allied to the latter by their social 
 instincts. 
 
 2. Scarcely less remarkable than the bee in their social organisa- 
 tion, they differ from that insect inasmuch as while the labours 
 of the latter are attended with no evil to mankind, but are, 
 on the contrary, productive of an eminently useful and agreeable 
 article of food, the Termites, so far as naturalists have yet dis- 
 covered, are productive of nethin^ but extensive and unmitigated 
 mischief. 
 
 3. These insects live in societies, each of which consists of 
 countless numbers of individuals, the large majority of which are 
 apterous, or wingless. Two individuals only in each society, a 
 male and a female, or according to some, a king and a queen, are 
 winged, and these alone in the entire society are specimens of the 
 perfect insect. The general form of their bodies is shown in 
 
 98 
 
THE KING AND QUEEN. 
 
 fig. I and fig. 2 ; tlie former representing the species called the 
 Termes emhia, with its wings expanded, and the latter the Termes 
 
 fatalis or hellicosus, with its wings folded. 
 
 4. With the exception of two or three small species, such as the 
 Termes lucifugus, described by Latreille and Eossi ; the Termes 
 
 Jf^avicoUis, described by Fabricins ; and the Termes Jlavtpes, de- 
 scribed by KoUar, these insects are confi.ned chiefly to the tropics. 
 
 0. Each society consists of fi.ve orders of individuals — 
 
 I. The queen or female. 
 
 II. The king or male. 
 III. The workers. 
 lY. The nymphs, 
 
 Y. The neuters or soldiers. 
 
 The Termes hellicosus or fatalis, which is represented in fig. 2, 
 with wings folded, is shown in fig. 3 with wings expanded. 
 
 The king or male, which never changes its form after losing its 
 wings, is represented in fig. 4. 
 
 6. The worker is represented in its natural size in. fig. 5, and 
 the soldier in fig. 6. 
 
 A magnified view of the worker is given in fig. 7, and a similar 
 magnified view of the forceps of the soldier in fig. 8. 
 
 1. The king and queen are privileged individuals, surrounded 
 with all the respect and consideration, and receiving all the 
 attendance and honours, due to sovereigns. Exempted from all 
 participation in the common industry of the society, they are 
 wholly devoted to increase and multiplication, the queen being 
 endowed with the most unbounded fertility. Though upon first 
 passing from the pupa state they have four wings, they lose 
 these appendages almost immediately, and during the period of 
 their sovereignty they are wingless. They are distinguished from 
 the inferior members of the society by the possession of organs of 
 vision, in the form of large and prominent eyes, their subjects 
 being all of them blind. 
 
 8. The workers are by far the most numerous members of the 
 society, being about a hundred times greater in number than the 
 soldiers. Their bodies also, fig. 5, are less than those of the sol- 
 diers, the latter being less than those of the sovereigns. The 
 entire industrial business of the society is performed by the workers. 
 They erect the common habitation, and keep it in repair. They 
 forage and collect provisions for the society. They attend upon 
 the sovereigns, and carry away the eggs of the queen, as fast 
 as she deposits them, to chambers which they previously prepare 
 for them. They maintain these chambers in order, and when the 
 eggs are hatched, they perform the part of nurses to the young, 
 
 H 2 99 
 
THE WHITE ANTS. 
 
 feeding and tending them until they have attained sufficient 
 growth to provide for themselves. 
 
 9. The soldiers, of whom, as already observed, there is not more 
 than one to every hundred workers, are distinguished by their 
 long and large heads, armed with long pointed mandibles. Their 
 duty, as their title implies, is confined to the defence of the society 
 and of their common habitation, when attacked by enemies. 
 
 10. The nymphs differ so little from the workers, that they 
 would be confounded with them, but that they have the rudi- 
 ments of wings, or, more strictly speaking, wings already formed, 
 folded up in wing cases. These escaped the notice of the earliest 
 observers, having been distinguished by Latreille. 
 
 11. Naturalists are not agreed as to the physiological character 
 of these three classes of the society. Some consider the workers 
 as the larvae which, at a certain advanced period of their growth, 
 are metamorphosed into the nymphs, which themselves finally pass 
 into the state of the perfect winged insect. 
 
 According to Kirby, the soldiers correspond to the neuters in 
 other societies of insects. As he observes, however, they differ 
 from the neuters of the societies of Hymenoptera, which are a sort 
 of sterile females. He conjectures that the soldiers may be the 
 larvee which are finally transformed into the perfect male insect. 
 Great differences of opinion, however, prevail on this subject among 
 entomologists. 
 
 For our present purpose, these doubtful questions, whatever 
 interest they may have for naturalists, are altogether unimportant. 
 What we desire at present to direct attention to, is the curious 
 manners and habits of these insects, which have been ascertained 
 by many eminent naturalists, and have been described with great 
 minuteness by Smeathman in the seventy-first volume of the Philo- 
 sophical Transactions, from whose memoir we shall here borrow 
 largely. 
 
 According to Smeathman, the following is the manner in which 
 the establishment of each colony takes place. 
 
 12. The pupae or nymphs, which compose, as has been stated, 
 part of a society, are transformed into the perfect insect, their 
 wings being fully developed and liberated from the wing eases 
 soon after the first tornado, which takes place at the close of the 
 dry season, and harbingers the periodical rains. The insects, thus 
 perfected, issue forth from their habitation in the evening, in 
 numbers literally countless, swarming after the manner of bees. 
 Borne upon their ample wings, and transported by the wind, they 
 fill the air, entering houses, extinguishing lights, and being some- 
 times driven on board ships which happen to be near the shore. 
 The next morning they are seen covering the surface of the earth 
 
 100 
 
USED FOR FOOD. 
 
 and waters, deprived of tlie wings which enabled them, for a 
 moment, to escape their numerous enemies. They are now seen 
 as large maggots, and, from being the most active, industrious, 
 and sagacious of creatures, are become utterly helpless and 
 cowardly, and fall a prey to innumerable enemies, to the smallest 
 of which they do not attempt to offer the least resistance. Yarious 
 insects, and especially ants, lie in wait for them ; beasts, birds, 
 and reptiles, and even man himself, all feed upon them, so that 
 not one pair in many millions make their escape in safety, and 
 fulfil the first law of nature by becoming the parents of a new 
 community. At this time they may be seen running upon the 
 ground, the male pursuing the female, and sometimes two pursu- 
 ing one, and contending with the greatest eagerness for the prize, 
 their passion rendering them regardless of the many dangers with 
 which they are surrounded. 
 
 13. Mr. Konig, in an essay upon these insects, read before the 
 society of na'turalists at Berlin, says that, in some parts of the 
 East Indies, the queens are given alive to old men for strengthen- 
 ing the back, and that the natives have a method of catching the 
 winged insects, which he calls females, before the time of emigra- 
 tion. They make two holes in the nest ; the one to windward 
 and the other to leeward. At the leeward opening, they place the 
 mouth of a pot, previously rubbed with an aromatic herb, called 
 Bergera, which is more valued there than the laurel in Europe. 
 On the windward side they light a fire of stinking materials, the 
 smoke of which not only drives these insects into the pots, but fre- 
 quently the hooded snakes also, on which account they are obliged 
 to be cautious in removing them. By this method they catch great 
 quantities, of which they make with flour a variety of pastry, 
 which they can afford to sell very cheap to the poorer ranks of 
 people. Mr. Konig adds, that in seasons when this kind of food 
 is very plentiful, the too great use of it brings on an epidemic 
 €holic and dysentery, which kills in two or three hours. 
 
 Mr. Smeathman says, that he did not find the Africans so 
 ingenious in procuring or dressing them. They are content with 
 a very small part of those which, at the time of swarming, or 
 rather of emigration, fall into the neighbouring waters, which 
 they skim of£ with calabashes, bringing large kettles full of them 
 to their habitations, and parch them in iron pots over a gentle fire, 
 stirring them about as is usually done in roasting coffee. In that 
 state, without sauce or any other addition, they serve them as 
 delicious food, and put them by handfuls into their mouths, as 
 we do comfits. Smeathman ate them dressed in this way several 
 times, and thought them delicate, nourisliing, and wholesome. 
 They are something sweeter, but not so fat or cloying, as the 
 
 101 
 
THE WHITE ANTS. 
 
 caterpillar or maggot of the palm-tree snout beetle, which 
 served up at all the luxurious tables of West Indian epicures, 
 particularly of the French, as the greatest dainty of the Western 
 World. 
 
 14. Troops of workers, apparently deprived of their king and 
 queen, which are constantly prowling about, occasionally encounter 
 one of these pairs, to which they offer their homage, and seem to 
 elect them as the sovereigns of their community, or the parents of 
 the colony which fhey are about to establish. All the individuals 
 of such a swarm, who are not so fortunate as to become the objects 
 of such an election, eventually perish under the attacks of the 
 enemies above mentioned, and probably never survive the day 
 which follows the evening of their swarming. 
 
 15. So soon as this election has been made, the workers begin 
 to enclose their new rulers in a small chamber of clay, suited to 
 their size, the entrances to which are only large enough to admit 
 themselves and the soldiers, but much too small for the royal pair 
 to pass through, so that their state of royalty is a state of confine- 
 ment, and so continues during the remainder of their lives. 
 
 16. The impregnation of the female is supposed to take place 
 after this confinement, and she soon begins to furnish the infant 
 colony with new inhabitants. The care of feeding her and her 
 male companion devolves upon the workers, who supply them both 
 with every thing that they want. As she increases in dimensions, 
 they keep enlarging the cell in which she is detained. When the 
 business of oviposition commences, they take the eggs from the 
 female, and deposit them in the nurseries. Her abdomen now 
 begins gradually to extend, till, in process of time, it is enlarged 
 to 1500 or 2000 times the size of the rest of her body, and her bulk 
 equals that of 20000 or 30000 workers. 
 
 17. A drawing of the pregnant queen in her natural size is 
 given in fig. 9. 
 
 Fig. 9. — The Pregnant Queen. 
 
 18. The abdomen, often more than three inches in length, is 
 now a vast matrix of eggs, which make long circumvolutions 
 through numberless slender serpentine vessels : it is also remark- 
 102 
 
THE EOYAL BODY-GUARD. 
 
 able for its peristaltic motion (in this resembling the female ant), 
 wbich, like the undulations of water, produces a perpetual and 
 successiYe rise and fall over its whole surface, and occasions a 
 constant extrusion of the eggs, amounting sometimes in old females 
 to sixty in a minute, or eighty thousand and upwards in twenty- 
 four hours. As these females live two years in their perfect state, 
 how astonishing must be the number produced in that time ! 
 
 19. This incessant extrusion of eggs must call for the attention 
 of a large number of the workers in the royal chamber (and indeed 
 it is always full of them), to take them as they come forth and 
 carry them to the nurseries; in which, when hatched, they are 
 provided with food, and receive every necessary attention until 
 they are able to shift for themselves. One remarkable circum- 
 stance attends these nurseries. They are always covered with a 
 kind of mould, amongst which arise numerous globules about the 
 size of a small pin's head. This probably is a species of Mucor ; and 
 by Mr. Konig, who found them also in nests of an East India 
 species of Termes, is conjectured to be the food of the larvse. 
 
 20. The royal cell has in it a kind of body-guard to the royal 
 pair that inhabit it ; and the surrounding apartments always 
 contain many, both labourers and soldiers in waiting, that they 
 may successively attend upon and defend the common father and 
 mother on whose safety depend the happiness and even existence 
 of the whole community, and whom these faithful subjects never 
 abandon, even in their last distress. 
 
 21. The habitations of the Termites, which are generally of 
 considerable magnitude, vary in form, arrangement, and position, 
 according to the species. Those of the Termes hellicosus, de- 
 scribed above, have generally a sugar-loaf or hay- cock form, and 
 are from ten to twelve feet high. In the parts of Africa where the 
 insect prevails, these structures are so numerous that it is scarcely 
 possible to find a spot from which they are not visible in all 
 directions within fifty or sixty yards. In the neighbourhood of 
 Senegal, according to Adanson, their number and magnitude is 
 so great that they cannot be distinguished from the native 
 villages. 
 
 22. When first erected, the external surfaces of these conical- 
 shaped habitations consist of naked clay, but in these fertile 
 climates the seeds of herbage transported by the wind are speedily 
 deposited upon them, which germinating soon clothe them with 
 the same vegetation as that which covers the surrounding soil, 
 and when in the dry and warm season this vegetable covering is 
 scorched, they assume the appearance of large hay-cocks. 
 
 23. These vast mounds are formed of earth which has been 
 excavated by the workers from extensive ^tunnels which have 
 
 103 
 
THE WHITE ANTS. 
 
 been carried beneath the ground surrounding their base, and 
 which supply covered ways by which the workers are enabled to 
 go forth in quest of provisions. The interior of the mounds 
 themselves are of most curious and complicated structure, con- 
 sisting of a variety of chambers and corridors, formed with the 
 most consummate art, and adapted in shape and size to the 
 respective purposes to which they are assigned in the general 
 economy of the colony. 
 
 24. In the superior part of the mound, a dome is constructed, 
 surmounting the habitations of the animals so as effectively to 
 shelter them from the vicissitudes of weather. This may be 
 seen in the vertical section of one of these mounds, shown in 
 fig. 10. The exterior covering of this dome is much stronger than 
 the internal structure beneath it, which constitutes the habita- 
 tion of the colony, and which is divided with surprising regu- 
 larity and contrivance into a vaSt number of chambers, one of 
 which is appropriated to the sovereigns, and the others distributed 
 among the soldiers, the workers, as nurseries, and as store-rooms. 
 
 The process by which these conical structures are raised is thus 
 described. 
 
 25. The habitation makes its first appearance as one or two 
 small sugar-loaf-shaped mounds about a foot in height. While 
 these are gradually increasing in height and magnitude, others 
 begin to appear near them, which likewise increase in number ; 
 and by the enlargement of their basis, they at length coalesce at 
 the lower parts. The middle mounds are always the highest, and 
 the largest, and by gradually filling up the intermediate space 
 by the enlargement of the bases of the several mounds, a single 
 mound, with various sugar-loaf-shaped masses of less magnitudes 
 growing out of it, is produced, as shown in fig. 10. 
 
 a a a. Turrets by which their hills are raised and enlarged. 
 
 2. A section of 1, as it would appear on being cut down through 
 
 the middle, from the top to the bottom, a foot lower than the 
 
 surface of the ground. 
 A A. An horizontal line from A on the left, and a perpendicular 
 
 line from A at the bottom will intersect each other at the 
 
 royal chamber. 
 
 The darker shades near it are the empty apartments and 
 passages, which, it seems, are left so for the attendants on 
 the king and queen, who, when old, may require near one 
 hundred thousand to wait on them every day. 
 
 The parts which are least shaded and dotted, are the 
 nurseries, surrounded, like the royal chamber, by empty 
 passages on all •ides, for the more easy access to them with 
 
 104 
 
THE WHITE ANTS. 
 
 tlie eggs from the queen, the provision for the young, &c. 
 JS'.B. The magazines of provisions are situated without any 
 seeming order, among the vacant passages which surround the 
 nurseries. 
 
 E. The top of the interior building, which often seems, from the 
 arches carried upward, to be adorned on the sides with 
 pinnacles. 
 
 c. The floor of the area or nave. 
 
 DDI). The large galleries which ascend from under all the 
 
 buildings spirally to the top. 
 E 3:. The bridge. 
 
 3. The first appearance of a hill-nest by two turrets. 
 
 4. A tree with the nest of the Termites arbortun, with their 
 
 covered way. 
 F F r E. Covered ways of the Termites arhorum. 
 0. The nest of the Termites arhoru7n. 
 
 6. A nest of the Termites hellicosi, with Europeans on it. 
 
 7. A bull standing sentinel upon one of these nests. 
 
 G G G. The African palm-trees from the nuts of which is made the 
 Oleum palmce. 
 
 26. When by the accumulation of these turrets the dome has 
 been completed, in which process the turrets supply the place of 
 scaffolding, the workers excavate the interior of them, and make 
 use of the clay in building the partitions and walls of the apart- 
 ments constructed in the base of the mound which constitutes 
 their proper habitation, and also for erecting fresh turrets sur- 
 mounting the mound and increasing its height. In this manner 
 the same clay, which, as has been already explained, was excavated 
 from the underground ways issuing around the mound, is used 
 several times over, just as are the posts and boards of a mason's 
 scaffolding. 
 
 27. When these mounds have attained a little more than half 
 their height, their tops being then flat, the bulls which are the 
 leaders of the herds of wild cattle which prevail in the surround- 
 ing country, are accustomed to mount upon them so as to obtain 
 a view of the surrounding plain : thus placed they act as sentinels 
 for the general herd which feeds and ruminates around them, 
 giving them notice of the approach of any danger. This circum- 
 stance supplies an incidental proof of the strength of these 
 structures. 
 
 28. Smeathman states that when he was in that country, and 
 desired to obtain a view of the sea to ascertain the approacli 
 of vessels, he was in the habit of mounting with three or four 
 of his assistants upon the summits of these conical mounds, 
 
 106 
 
THE EOYAL CHAMBER. 
 
 the elevation of which was sulhcient to enable him to obtain a 
 satisfactory view. 
 
 29. The superior shell or dome bj which the mound is sur- 
 mounted is not only of use to protect the interior buildings from 
 external violence and from the tropical rains, but, from its non- 
 conducting quality, to preserve that uniform temperature within, 
 which is necessary for hatching the eggs and cherishing the 
 young. 
 
 30. The royal chamber appropriated to the sovereigns engrosses 
 much of the attention and skill of their industrious subjects. It: 
 is generally placed about the centre of the base of the mound, at 
 the level of the surrounding ground, and has the shape of halt* 
 an egg divided by a plane a,t right angles to its axis passing a 
 little below its centre. Thus the shape of this chamber is that 
 which architects call a surmounted dome. Its magnitude is pio- 
 portioned to that of the king and queen to whom it is appropriated.. 
 In the infant state of the colony, before the queen is advanced in 
 pregnancy, the diameter of this room does not exceed an inch , 
 but as the royal lady increases in the manner already described, 
 the workers continually enlarge the room, until at length it: 
 attains a diameter of eight or nine inches. Its floor is perfectly 
 level, and formed of clay about an inch thick. The roof is formed, 
 of a solid well-turned oval arch increasing in thickness from a. 
 quarter of an inch at the sides where it rests upon the floor. 
 
 31. The doors are cut in the wall, and made of a magnitude 
 suitable to the entrance and exit of the soldiers and workers who 
 attend on the royal pair, but much too small for the passage of the- 
 royal personages themselves. 
 
 32. This large chamber is surrounded by numerous others of 
 less dimensions, and various shapes, all of which have arched 
 roofs, some circular, and some elliptical. These chambers com- 
 municate with each other by doors and corridors. Those which 
 are immediately contiguous to the royal chamber are appropriated 
 to the soldiers, who are in immediate attendance on the sovereign, 
 and to the workers, whose duty it is to supply and attend the royal 
 table, and to carry away the eggs as fast as they are laid by the 
 queen. 
 
 33. Around these antechambers is another suite of apart- 
 ments, consisting of store-rooms for provisions, chambers for the 
 reception of the eggs, and nurseries for the young. The store- 
 rooms are constructed like other parts of the habitation, with walls, 
 and partitions of clay, and are always amply supplied with provi- 
 sions, which, to the naked eye, seem to consist of the raspings of 
 wood and plants, which the workers destroy. Upon submitting 
 them to the microscope, however, they are found to consist prin- 
 
 107 
 
THE WHITE ANTS. 
 
 cipally of vegetable gums and inspissated juices. These are 
 thrown together in masses of different appearance, some resem- 
 bling the sugar on preserved fruits, some transparent, and others 
 •opaque, as is commonly seen in all parcels of gum. 
 
 The nurseries, on the other hand, are constructed in a manner 
 totally different from the other rooms. 
 
 34. The walls and partitions of these consist entirely of wooden 
 materials, cemented together with gum. These nurseries, in 
 which the eggs are hatched, and the young secured, are small 
 irregularly shaped rooms, none of which exceed half an inch in 
 width. 
 
 35. "When the nest is in the infant state, the nurseries are 
 •close to the royal chamber ; but as in process of time the queen 
 •enlarges, it is necessary to enlarge the chamber for her accommo- 
 dation ; and as she then lays a great number of eggs, and requires 
 a, greater number of attendants, so it is necessary also to enlarge 
 and increase the number of the antechambers ; for which purpose 
 the small nurseries first built' are taken to pieces, rebuilt a little 
 further off a size larger, and their number increased. 
 
 36. Thus they continually enlarge their apartments, pull down, 
 repair, or rebuild, according to their wants, with a degree of 
 sagacity, regularity, and foresight, not observed among any other 
 kind of animals or insects. 
 
 37. There is one remarkable circumstance attending the nur- 
 series which ought not to be omitted. They are always found 
 slightly overgrown with mould, and plentifully sprinkled with 
 v/hite globules, about the sise of the head of a small pin. These 
 may be at first mistaken for eggs ; but submitting them to the 
 microscope, they appear to be a species of mushroom, similar 
 to the common mushroom, of the sort usually pickled. They 
 appear, when whole, white like snow a little thawed and after- 
 wards frozen ; and, when bruised, seem to be composed of an 
 infinite number of pellucid particles, having a nearly oval form, 
 and difl&cult to be separated. The mouldiness seems to be com- 
 posed of the same kind of substance. The nurseries are enclosed 
 in chambers of clay, like the store-rooms, but much larger. In 
 the early state of the nest, they are not bigger than a hazel-nut, 
 but in large hills are much more spacious. 
 
 38. These magazines and nurseries, separated by small empty 
 chambers and galleries, which run round them, or communicate 
 from one to the other, are continued on all sides to the outer wall 
 of the building, and reach up within it to two-thirds or three- 
 fourths of its height. They do not, however, fill up the whole of 
 the lower part of the hill, but are confined to the sides, leaving 
 an open area in the middle, under the dome, very much resem- 
 
 108 
 
SUBTERRANEOUS PASSAGES. 
 
 bling the nave of an old cathedral, having its roof supported by- 
 three or four very large Gothic arches, of which those in the 
 middle of the area are sometimes two and three feet high ; but 
 as they recede on each side, rapidly diminish, like the arches of 
 aisles in perspective. A flattish roof, without perforation, in 
 order to keep out the wet, if the dome should chance to be 
 injured, covers the top of the assemblage of chambers, nurseries,, 
 &c. ; and the area, which is above the royal chambers, has a flat- 
 tish floor, also water-proof, and so contrived as to let any rain 
 that may chance to get in, run off into the subterraneous pas- 
 sages which run from the basement of the lower apartments- 
 through the hill in various directions ; and one of astonishing 
 magnitude, often having a bore greater than that of a large piece 
 of ordnance. Smeathman measured the diameter of one of 
 these passages, which was perfectly cylindrical, and found it tO" 
 be thirteen inches. 
 
 39. These subterraneous passages, or galleries, are lined very 
 thick with the same kind of clay of which the hill is composed, and 
 ascend the inside of the outer shell in a spiral manner, and 
 winding round the whole building, up to the top, intersect each 
 other at different heights, opening either immediately into the 
 dome in various places, and into the interior building, the 
 new turrets, &c., or communicating thereto by other galleries of 
 different bores or diameter, either circular or oval. 
 
 From every part of these large galleries are various small 
 tunnels or galleries, leading to different parts of the building. 
 Under ground there are many which lead downward, by sloping 
 descents, three or four feet perpendicular, among the gravel, 
 from whence the workers cull the finer parts, which, being 
 worked up in their mouths to the consistence of mortar, become 
 that solid clay of which their hills and all their buildings, except 
 their nurseries, are composed. 
 
 40. Other galleries again ascend, and lead out horizontally on 
 every side, and are carried under ground, near to the surface, to 
 a vast distance : for if you destroy all the nests within one 
 hundred yards of your house, the inhabitants of those which are 
 left unmolested farther off will, nevertheless, carry on their 
 subterraneous galleries, and invade the goods and merchandises 
 contained in it by sap and mine, and do great mischief, if you 
 are not very circumspect. 
 
 41. But to return to the cities from whence these extraordinary 
 expeditions and operations originate, it seems there is a degree 
 of necessity for the galleries under the hills being thus large, 
 being the great thoroughfares for all the labourers and soldiers 
 going forth or returning upon any business whatever, whether 
 
 109 
 
THE VfHlTE ANTS. 
 
 fetcliirig clay, wood, water, or provisions ; and they are certainly 
 well calculated for the purposes to wMcli they are applied, by the 
 spiral slope which is given them ; for if they were perpendicular, 
 the labourers would not be able to carry on their building with so 
 much facility, since they cannot ascend a perpendicular without 
 great difficulty, and the soldiers can scarcely do it at all. 
 It is on this account that sometimes a road, like a ledge, is 
 made on the perpendicular side of part of the building within 
 their hill, which is flat on the upper surface, and half an inch 
 wide, and ascends gradually like a staircase, or like those 
 roads which are cut on the sides of hills and mountains, that 
 would otherwise be inaccessible ; by which, and similar con- 
 trivances, they travel with great facility to every interior part. 
 
 42. This too is probably the cause of their building a kind of 
 ibridge of one vast apch, which answers the purpose of a flight of 
 stairs from the floor of the area to som« opening on the side 
 of one of the columns which support the great arches. Such 
 bridges shorten the distance considerably to those labourers v/ho 
 have the eggs to carry from the royal chamber to some of the 
 upper nurseries, which in some hills would be four or Ave feet in 
 the straightest line, and much more if carried through all the 
 winding passages which lead through the inner chambers and 
 apartments. 
 
 Smeathman found one of these bridges half an inch broad, a 
 quarter of an inch thick, and ten inches long, maldng the side of 
 £in elliptic arch of proportional size ; so that it is wonderful it 
 ■did not fall over or break by its own weight before they got it 
 joined to the side of the column above. It was strengthened by a 
 small arch at the bottom, and had a hollow or groove all the length 
 of the upper surface, either made purposely for the inhabitants 
 to travel over with more safety, or else, which is not improbable, 
 w^orn so by frequent treading. 
 
 43. " Consider," observes Kirby, " what incredible labour and 
 diligence, accompanied by the most unremitting activity and the 
 most unwearied celerity of movement, must be necessary to enable 
 these creatures to accomplish, their size considered, these truly 
 gigantic works. That such diminutive insects, for they are 
 scarcely the fourth of an* inch in length, however numerous, 
 should, in the space of three or four years, be able to erect a 
 building twelve feet high, and of a proportionable bulk, covered by 
 a vast dome, adorned without by numerous pinnacles and turrets, 
 and sheltering under its ample arch myriads of vaulted apart- 
 ments of various dimensions, and constructed of different materials 
 — that they should moreover excavate, in different directions, and 
 at different depths, innumerable subterranean roads or tunnels^ 
 
 110 
 
THEIE MAEVELLOTJS WORKS. 
 
 some twelve or thirteen inclies in diameter, or throw an arch, of 
 stone over other roads leading from the metropolis into the 
 Adjoining country to the distance of several hundred feet — that 
 they should project and finish the, for them, vast interior stair- 
 oases or bridges lately described — and, finally, that the millions 
 necessary to execute such Herculean labours, perpetually passing 
 to and fro, should never interrupt or interfere with each other, 
 is a miracle of nature, or rather of the Author of nature, far 
 exceeding the most boasted works and structures of man : for, 
 did these creatures equal him in size, retaining their usual instincts 
 and activity, their buildings would soar to the astonishing height 
 of more than half a mile, and their tunnels would expand to a 
 magnificent cylinder of more than three hundred feet in diameter ; 
 before which the pyramids of Egypt and the aqueducts of Rome 
 would lose all their celebrity, and dwindle into nothings. 
 
 The most elevated of the pyramids of Egypt is not more than 
 BOO feet high, which, setting the average height of man at only 
 five feet, is not more than 120 times the height of the workmen 
 employed. Whereas the nests of the Termites being at least 
 twelve feet high, and the insects themselves not exceeding a 
 quarter of an inch in stature, their edifice is upwards of 500 times 
 the height of the builders ; which, supposing them of human 
 dimensions, would be more than half a mile. The shaft of the 
 Iloman aqueducts was lofty enough to permit a man on horseback 
 to travel in them." * 
 
 44. The bodies of the Termites are generally soft and covered 
 with a thin and delicate skin, and being blind, they are no match 
 •on the open ground for the ants who are endowed with vision, and 
 whose bodies are invested in a strong horny shell. Whenever the 
 Termites are accidentally dislodged from their subterraneous 
 roads or dwellings, the various species of ants instantly seize 
 them and drag them away to their nests as food for their young. 
 
 45. The Termites are therefore very solicitous about preserving 
 their tunnels and vaulted roads in good repair. If some of them 
 be accidentally demolished for a few inches in length, it is wonder- 
 ful how speedily they rebuild it. At first, in their hurry, they 
 advance into the open part for an inch or two, but stop so suddenly 
 that it is very apparent that they are surprised, for although some 
 run straight on until they get under the arch beyond the damaged 
 part, most of them run as fast back, and very few of them will 
 venture through that part of the track which is left uncovered. 
 In a few minutes, however, they will be seen rebuilding the arch, 
 and even if three or four yards in length have been destroyed, they 
 will reconstruct it in a single day. If this be again destroyed, 
 
 • Kirby, vol. i. p. 43i. 
 
THE WHITE ANTS. 
 
 they will be seen as numerous as ever passing both ways along it, 
 and they will again in like manner reconstruct it. But if the 
 same part be destroyed several times successively, they will give- 
 up the point and build a new covered way in another direction. 
 Nevertheless, if the old one should lead to some favourite source 
 of plunder, they will, after a few days' interval, still reconstruct it,, 
 apparently in the hope that the cause of destruction will not agaiii 
 occur, nor will they in that case wholly abandon the undertakiuj^ 
 unless their habitation itself be destroyed. 
 
 112 
 
Fig. 6.— Soldier. 
 
 Fig. 7. — Worker, magnified. 
 
 THE WHITE ANTS, 
 
 THEIR MANNERS AND HABITS. 
 
 CHAPTEE II. 
 
 46. Turrets built by the Termes mordax and the Termes atrox. — 47. De- 
 scriptioa of their structure. — 48. Their king, queen, worker, and 
 soldier. — 49. Internal structure of their habitation. — 50. Nests of the 
 Termes arborum. — 51. Process of their construction. — 52. Hill nests 
 on the Savannahs. — 53. The Termes lucifugus — the organisation cf 
 their societies. — 54. Habits of the workers and soldiers— the materials 
 they use for building. — 55. Their construction of tunnels. — 56. Nests 
 of the Termes arborum in the roofs of houses. — 57. Destructive habits 
 of the Termes bellicosus in excavating all species of wood-work — 
 entire houses destroyed by them. — 58. Curious process by which they 
 lill with mortar the excavations which they make — destruction of 
 Mr. Smeathman's microscope. — 59. Destruction of shelves and wain- 
 scoting. — 60. Their artful process to escape observation. — 61. 
 Anecdotes of them by Kcerapfer and Humboldt. — 62. Destruction of 
 the Governor's house at Calcutta — destruction by them of a British 
 ship of the line. — 63. Their manner of attacking timber in the open 
 air— their wonderful power of destroying fallen timber. — 64. The 
 extraordinary behaviour of the soldiers when a nest is attacked. 
 
 Lakdner's Museum .OF Science. I 113 
 
 No. 108. " . , : 
 
THE WHITE ANTS. 
 
 65. Tlieir rage and fury against those who attack them. — 66. Their 
 industry and promptitude in repairing the damage of their habitation. 
 — 67. The vigilance of the soldiers during the process of repair. — 
 68. Effects of a second attack on their habitation, conduct .of the 
 soldiers. — 69. Difficulty of investigating the structure of their habita- 
 tions — obstinate opposition of the soldiers — discovery of the royal 
 chamber — fidelity of the subjects to the sovereign — curious experiment 
 of Mr. Smeathman. — 70. Curious example of the repair of a partially 
 destroyed nest. — 71. The marching Termites — curious observation of 
 their proceedings by Smeathman — remarkable conduct of the soldiers 
 on the occasion. 
 
 46. A smaller species of Termites erect habitations, whicli, if 
 they are of less dimensions, are not less curious in their structure. 
 
 These buildings are upright cylinders, composed of a well- 
 tempered black earth or clay, about three quarters of a yard high, 
 and covered with a roof of the same material in the shape of a 
 cone, whose base extends over and hangs down three or four 
 inches wider than the perpendicular sides of the cylinder, so that 
 most of them resemble in shape a round Avindmill, or still more 
 closely the round towers which are so frequently seen in Ireland,, 
 and which have attracted so much attention on the part of 
 antiquaries. Some of these roofs have so little elevation in the 
 centre, that they have a close resemblance to certain species of 
 mushroom. 
 
 After one of these turrets is finished, it is not altered or 
 enlarged ; but when no longer capable of containing the commu- 
 nity, the foundation of another is laid within a few inches of it.. 
 Sometimes, though but rarely, the second is begun before the 
 first is finished, and a third before they have completed the 
 second: thus they will run up five or six of these turrets at 
 the foot of a tree in the thick woods, and make a most singular 
 group of buildings, as shown in fig. 11. 
 
 1 Nest of the Vermes mordax, 
 
 2 Nest of the Termes atrox. 
 
 3 A turret with the roof begun. 
 
 4 A turret raised only about half its height. 
 
 5 A turret built upon one which has been thrown down, 
 
 6 6 A turret broken in two. 
 
 47. The turrets are so strongly built, that in case of violence 
 they wiU much sooner overset from the foundations, and tear up 
 the ground and solid earth, than break in the middle ; and in that 
 case the insects will frequently begin another turret and build it, 
 as it were, through that which has fallen ; for they will connect 
 the cylinder below with the ground, and run up a new turret from 
 its upper side, so that it will seem to rest upon the horizontal 
 cylinder only. 
 
 114 
 
TUEKET NESTS. 
 Fig. 11. 
 
 The Turret Nests of the Termes Mordax and Termes Atrox- 
 
 I 2 115 
 
THE WHITE ANTS. 
 
 48. In fig. 12 is represented the king or queen of the Termes 
 mordaxy in fig. 13 the worker, and in fig. 14 the soldier. 
 
 TEKMES MORDAX. 
 T'ig- 12. Fig. 13. Fig. 14. 
 
 Worker. Soldier. 
 
 King or Queen. 
 
 The building is divided into innumerable cells of irregular 
 shapes ; sometimes they are quadrangular or cubic, acd sometimes 
 }»eiitagonal ; but often the angles are so ill defined, that each half 
 of a cell will be shaped like the inside of that shell which is 
 called the sea- car. 
 
 49. Each cell has two or more entrances, but as there are no 
 tunnels or galleries, no variety of apartments, no well-turned 
 arches, wooden nurseries, &c., &c., as in the habitations already 
 described, they are not calculated to excite the same degree of 
 wonder, however admirable they may be considered without 
 reference to other structures. 
 
 There are two sizes of these turret nests, built by two different 
 species of Termites. The larger species, the Termes atrox, in its 
 perfect state, measures one inch and three-tenths from the 
 extremities of the wings on the one side to the extremities on the 
 other. The lesser, Termes mordaxy measures only eight-tenths 
 of an inch from tip to tip. 
 
 50. The next kind of nests, built by another species of this 
 genus, the Termes arborum, have very little resemblance to the 
 former in shape or substance. These are generally spherical or 
 oval, built in trees : sometimes they are established between, and 
 sometimes surrounding, the branches, at the height of seventy or 
 eighty feet ; and are occasionally as large as a great sugar-cask. 
 
 51. They are composed of small particles of wood and the various 
 gums and juices of trees, combined with, perhaps, those secreted 
 by the animals themselves, worked by those little industrious 
 creatures into a paste, and so moulded into innumerable little cells 
 of different and irregular forms. These nests, with the immense 
 quantity of inhabitants, young and old, with which they are at 
 all times crowded, are used as food for young fowls-, and especially 
 for the rearing of Turkeys. These nests are very compact, and 
 50 strongly fixed to the boughs, that there is no detaching them 
 but by cutting them in pieces, or sawing off the branch. They 
 will even sustain the force of a tornado as long as the tree to 
 
 116 
 
TREE AKT'S nest. 
 
 which they are attached. This species has the external habit, 
 size, and almost the colour, of the Termes atrox. 
 
 52. There are some nests that resemble the hill-nests first 
 described, built in those sandy plains called Savannahs. They 
 are composed of black mud, raised from a few inches below the 
 white sand, and are built in the form of an imperfect or bell- 
 shaped cone, having their tops rounded. These are generally 
 about four or five feet high. They seem to be inhabited by 
 insects nearly as large as the Termes hellicosus, and differing very 
 little from that species, except in colour, which is brighter. 
 
 53. The societies of Termes lucifugus, discovered by Latreille 
 at Bourdeaux, are very numerous ; but instead of making arti- 
 ficial nests, they make their lodgments in the trunks of pines 
 and oaks, where the branches diverge from the tree. They 
 eat the wood the nearest the bark without attacking the interior, 
 and bore a vast number of holes and irregular galleries. That 
 part of the wood appears moist, and is covered with little gelatinous 
 particles, not unlike gum-arabic. These insects seem to be fur- 
 nished with an acid of a very penetrating odour, which, perhaps, 
 is useful to them in softening the wood. The soldiers in those 
 societies are as about one to twenty-five of the labourers. 
 
 The anonymous author of the Observations on the Termites of 
 Ceylon, seems to have discovered a sentry-box in his nests. "I 
 found," says he, in a very small cell in the middle of the solid 
 mass, (a cell about half an inch in height, and very narrow,) a 
 larva with an enormous head. Two of these individuals were in 
 the same cell ; one of the two seemed placed as sentinel at the 
 entrance of the cell. I amused myself by forcing the door two or 
 three times ; the sentinel immediately appeared, and only 
 retreated when the door was on the point to be stopped up, 
 which was done in three minutes by the labourers." 
 
 54. Having thus given some idea of their habitations, we shall 
 now direct our observations to the insects themselves, their 
 manner of building, fighting, and marching, and to a more 
 particular account of the vast mischief they cause to mankind. 
 
 It is a common character of the different species which have 
 been noticed, that the workers and the soldiers never expose 
 themselves in the open aii-, but invariably travel either under 
 ground, or along the holes which they bore in trees and other 
 substances. When in certain exceptional cases in quest of 
 plunder they are compelled to move above ground, they make a 
 vault with a coping of earth, or a tube, formed of that material 
 with which they build their nests, along which they travel com- 
 pletely protected. The Termes hellicosus iises for this purpose 
 the red, and the turret-builders black clay ; whilst the Termes 
 
 117 
 
THE WHITE ANTS. 
 
 arhorum employs for the purpose the ligneous substances of which 
 their nests are composed. 
 
 55. With these materials they completely line most of the roads 
 leading from their nests into the various parts of the country, 
 and travel out and home with the utmost security in all kinds of 
 weather. If they meet a rock or any other obstruction, they will 
 make their way upon the surface, and for that purpose erect a 
 covered way or arch, still of the same materials, continuing it 
 with many windings and ramifications through large grooves, 
 having, where it is possible, subterranean pipes running parallel 
 with them, into which they sink, and save themselves, if their 
 galleries above ground are destroyed by any violence, or the tread 
 of men or animals alarms them. When any one chances by accident 
 to enter any solitary grove, where the ground is pretty well 
 covered with their arched galleries, they give the alarm by loud 
 hissings, which he hears distinctly at every step he makes ; soon 
 after which he may examine their galleries in vain for the insects, 
 which escape through little holes, just large enough for them, 
 into their subterraneous roads. These galleries are large enough 
 for them to pass and repass, so as to prevent any stoppages, and 
 shelter them equally from light and air, as well as from their 
 enemies, of which the ants, being the most numerous, are the 
 most formidable. 
 
 56. The Termites arhorum^ those which build in trees, fre- 
 quently establish their nests within the roofs and other parts of 
 houses, to which tho}^ do considerable damage if not extirpated. 
 
 57. The larger species are, however, not only much more 
 destructive, but more difficult to be guarded against, since they 
 make their approaches chiefly under ground, descending below 
 the foundations of houses and stores at several feet from the 
 surface, and rising again either in the floors, or entering at the 
 bottoms of the posts, of which the sides of the buildings arc 
 composed, bore quite through them, following the course of the 
 fibres to the top, or making lateral perforations and cavities here 
 and there as they proceed. 
 
 While some are employed in gutting the posts, others ascend 
 from them, entering a rafter or some other part of the roof. If 
 they once find the thatch, which seems to be a favourite food, 
 they soon bring up wet clay, and build their pipes or galleries 
 through the roof in various directions, as long as it will support 
 them, sometimes eating the palm-tree leaves and branches of 
 which it is composed, and perhaps (for variety seems very pleasing 
 to them) the rattan or other running plant which is used as a cord 
 to tie the various parts of the roof together, and to the posts 
 which support it ; thus, with the assistance of the rats, who, 
 118 
 
THE DESTRUCTION THEY EFFECT. 
 
 during the rainy season, are apt to shelter themselves there, and 
 to burrow through it, they very soon ruin the house by weakening 
 the fastenings and exposing it to the wet. In the meantime, the 
 posts will be perforated in every direction, as full of holes as that 
 timber in the bottom of ships which has been bored by the worms ; 
 the fibrous and knotty parts, which are the hardest, being left to 
 the last. 
 
 58. They sometimes, in carrying on this business, find that the 
 post has some weight to support, and then, if it is a convenient 
 track to the roof, or is itself a kind of wood agreeable to them, 
 they bring their mortar, and fill all or most of the cavities, 
 leaving the necessary roads through it, and as fast as they take 
 away the wood, replace the vacancy with that material ; which 
 being worked together by them closer and more compactly than 
 human strength or art could ram it, when the house is pulled to 
 pieces, in order to examine if any of the posts are fit to be used 
 again, those of the softer kinds are often found reduced almost to 
 a shell, and all, or a greater part, transformed from wood to clay, 
 as solid and as hard as many kinds of freestone used for building 
 in England. 
 
 It is much the same when the Termites hellicosi get into a 
 chest or trunk containing clothes and other things ; if the 
 weight above is great, or they are afraid of ants and other 
 enemies, and have time, they carry their pipes through, and 
 replace a great part with clay, running their galleries in various 
 directions. The tree-Termites, indeed, when they get within a 
 box, often make a nest there, and being once in possession destroy 
 it at their leisure. They did so in a pyramidal box which 
 contained the compound microscope of Mr. Smeathman. It was 
 of mahogany, and he deposited it in the warehouse of Grovernor 
 Campbell of Tobago, while he made a tour of a few months in the 
 Leeward Islands. On his return he found that the Termites had 
 done much mischief in the warehouse, and, among other things, 
 had taken possession of the microscope, and eaten everything 
 about it except the glass or metal, including the board on which 
 the pedestal is fixed, with the drawers under it, and the things 
 enclosed. The cells were built all round the pedestal and the 
 tube, and attached to it on every side. All the glasses were 
 covered with the wooden substance of their nests, and retained 
 a cloud of a gummy nature upon them which was not easily got 
 ofi", and the lacquer or burnish with which the brasswork was 
 covered was totally spoiled. 
 
 Another party had taken a liking to a cask of Madeira, and 
 had bored so as to discharge almost a pipe of fine old wine. If 
 the large species of Africa (the Termites hellicosi) had been so 
 
 . 119 
 
THE WHITE ANTS. 
 
 long in the uninterrupted possession of such, a warehouse, they 
 would not have left twenty pounds weight of wood remaining of 
 the whole building, and all that it contained. 
 
 59. These insects are not less expeditious in destroying the 
 shelves, wainscotting, and other fixtures of a house, than the 
 house itself. They are for ever piercing and boring in all direc- 
 tions, and sometimes go out of the broadside of one post into that 
 of another joining to it ; but they prefer, and always destroy the 
 softer substances the first, and are particularly fond of pine and 
 fir-boards, which they excavate and carry away with wonderful 
 despatch and astonishing cunning ; for, unless a shelf has some- 
 thing standing upon it, as a book, or anything else which may 
 tempt them, they will not perforate the surface, but artfully 
 preserve it quite whole, and eat away all the inside, except a 
 few fibres which barely keep the two sides connected together, so 
 that a piece of an inch board which appears solid to the eye will 
 not weigh much more than two sheets of pasteboard of equal 
 dimensions, after these animals have been a little while in posses- 
 sion of it. 
 
 60. In short the Termites are so insidious in their attacks, that 
 we cannot be too much on our guard against them : they will 
 sometimes begin and raise their works, especially in new houses, 
 through the floor. If you destroy the work so begun, and make 
 a fire upon the spot, the next night they will attempt to rise 
 through another part; and, if they happen to emerge under a 
 chest or trunk early in the night, will pierce . the bottom, and 
 destroy or spoil everything in it before morning. On these 
 accounts care is taken by the inhabitants of the country to set all 
 their chests and boxes upon stones or bricks, so as to leave the 
 bottoms of such furniture some inches above the ground ; which 
 not only prevents these insects finding them out so readily, but 
 preserves the bottoms from a corrosive damp which would strike 
 from the earth through, and rot everything therein ; a vast deal 
 of vermin would also harbour under, such as cockroaches, centi- 
 pedes, millepedes, scorpions, ants, and various other noisome 
 insects. 
 
 61. Koempfer, speaking of the white ants of Japan, gives a 
 remarkable instance of the rapidity with which these miners 
 proceed. Upon rising one morning, he observed that one of their 
 galleries, of the thickness of his little finger, had been formed 
 across his table ; and upon a further examination he found that 
 they had bored a passage of that thickness up one foot of the 
 table, formed a gallery across it, and then pierced down another 
 foot into the floor ; all this was done in the few houi's that inter- 
 vened between his retiring to rest and his rising. They make 
 
 120 
 
THEIR VORACITY. 
 
 tlieir way also with the greatest ease into trunks and boxes, even 
 though made of mahogany, and destroy papers and everything 
 they contain, constructing their galleries and sometimes taking 
 up their abode in them. Hence, as Humboldt informs us, through- 
 out all the warmer parts of equinoctial America, where these 
 and other destructive insects abound, it is infinitely rare to find 
 papers which go fifty or sixty years back. In one night they 
 will devour all the boots and shoes that are left in their way; 
 cloth, linen, or books are equally to their taste ; but they will 
 "not eat cotton. They entirely consumed a collection of insects 
 made in India. In a word, scarcely anything but metal or stones 
 comes amiss to them. 
 
 62. It is even asserted that the superb residence of the Governor- 
 General at Calcutta, which cost the East India Company such • 
 immense sums, is now rapidly going to decay in consequence of 
 the attacks of these insects. But not content with the dominions 
 they have acquired, and the cities they have laid low on terra 
 firma, encouraged by success, the white ants have also aimed at 
 the sovereignty of the ocean, and once had the hardihood to 
 attack even a British ship of the line ; and in spite of the efforts 
 of the commander and his valiant crew, having boarded they got 
 possession of her, and handled her so roughly, that when brought 
 into port, being no longer fit for service, she was obliged to be 
 broken up. 
 
 The ship here alluded to was the Albion, which was in such a 
 condition from the attack of these insects, that had it not been 
 firmly lashed together, it was thought she would have foundered 
 on her voyage home. The late Mr. Kittoe stated that the droguers 
 or draguers, a kind of lighter employed in the West Indies in 
 collecting the sugar, sometimes so swarm with ants of the common 
 kind, that they have no other way of getting rid of these trouble- 
 some insects than by sinking the vessel in shallow water. 
 
 63. When the Termites attack trees and branches in the open 
 air, they sometimes vary their manner of doing it. If a stake in a 
 hedge has not taken root and vegetated, it becomes their business 
 to destroy it. If it has a good sound bark round it, they will 
 enter at the bottom, and eat all but the bark, which will remain, 
 and exhibit the appeai'ance of a solid stick (which some vagrant 
 colony of ants or other insects often shelter in, till the winds 
 disperse it) ; but if they cannot trust the bark, they cover the 
 whole stick with their mortar, and it then looks as if it had been 
 dipped into thick mud that had been dried on. Under this 
 covering they work, leaving no more of the stick and bark than 
 is barely sufficient to support it, and frequently not the smallest 
 particle, so that upon a very small tap with your walking stick, 
 
 121 
 
THE WHITE ANTS. 
 
 the whole stake, though apparently as thick as your arm, and five 
 or six feet long, loses its form, and, disappearing like a shadow, 
 falls in small fragments at your feet. They generally enter the 
 body of a large tree which has fallen through age, or been thrown 
 down by violence, on the side next the ground, and eat away at 
 their leisure within the bark, without giving themselves the 
 trouble either to cover it on the outside, or to replace the wood 
 which they have removed from within, being somehow sensible 
 that there is no necessity for it. "Such excavated trees," says 
 Mr. Smeathman, "deceived me two or three times in running ; 
 for, attempting to step two or three feet high, I might as well 
 have attempted to step upon a cloud, and have come down with 
 such unexpected violence, that, besides shaking my teeth and 
 bones almost to dislocation, I have been precipitated head fore- 
 most among the neighbouring trees and bushes." Sometimes, 
 though seldom, the animals are known to attack living trees ; but 
 not before symptoms of mortification have appeared at the roots ; 
 since it is evident that these insects are intended in the order of 
 nature to hasten the dissolution of such trees and vegetables as 
 have arrived at their greatest maturity and perfection, and which 
 would, by a tedious decay, serve only to encumber the face of the 
 earth. This purpose they answer so effectually that nothing 
 perishable escapes them, and it is almost impossible to leave any- 
 thing penetrable upon the ground a long time in safety ; for the 
 odds are, put it where you will abroad, they wiU find it out 
 before the following morning, and its destruction follows very 
 soon of course. In consequence of this disposition, the woods 
 never remain long encumbered with the fallen trunks of trees or 
 their branches ; and thus it is that the total destruction of deserted 
 towns is so effectually completed, that in two or three years a 
 thick wood fills the space ; and, unless iron-wood posts have been 
 made use of, not the least vestige of a house is to be discovered. 
 
 64. The first object of admiration, which strikes one upon 
 opening their hills, is the behaviour of their soldiers. If you 
 make a breach in a slight part of the building, and do it quickly, 
 with a strong hoe or pick-axe, in the space of a few seconds a 
 soldier will run out, and walk about the breach, as if to see 
 whether the enemy is gone, or to examine what is the cause of 
 the attack. He will sometimes go in again, as if to give the 
 alarm ; but most frequently, in a short time, is followed by two 
 or three others, who run as fast as they can, straggling after one 
 another, and are soon followed by a large body, who rush out as 
 fast as the breach will permit them, and so they proceed, the 
 number increasing, as long as any one continues battering their 
 building. It is not easy to describe the rage and fury they show. 
 122 
 
FEROCITY OF THE SOLDIERS. 
 
 In their hurry they frequently miss their hold, and tumble 
 down the sides of the hill, but recover themselves as quickly as 
 possible ; and being blind, bite everything they run against, and 
 thus make a crackling noise, while some of them beat repeatedly 
 with their forceps upon the building, and make a small vibrating 
 noise, something shriller and quicker than the ticking of a watch. 
 This noise can be distinguished at three or four feet distance, and 
 continues for a minute at a time, with short intervals. "While 
 the attack proceeds, they are in the most violent bustle and 
 agitation. 
 
 65. If they get hold of any one they will, in an instant, 
 let out blood enough to weigh against their whole body; and 
 if it is the leg they wound, you will see the stain upon the 
 stocking extend an inch in width. They make their hooked 
 jaws meet at the first stroke, and never quit their hold, but 
 suffer themselves to be pulled away leg by leg, and piece after 
 piece, without the least attempt to escape. On the other hand, 
 keep out of their way, and give them no interruption, and they 
 will, in less than half an hour, retire into the nest, as if they sup- 
 posed the wonderful monster that damaged their castle to be gone 
 beyond their reach. 
 
 66. Before they are all got in, you will see the labourers in 
 motion, and hastening in various directions towards the breach ; 
 every one with a burthen of mortar in his mouth ready tempered. 
 This they stick upon the breach as fast as they come up, and do 
 it with so much dispatch and facility, that although there are 
 thousands, and even millions of them, they never stop or embarrass 
 one another ; and you are most agreeably deceived when, after 
 an apparent scene of hurry and confusion, a regular wall arises, 
 gradually filling up the chasm. While they are thus employed, 
 almost all the soldiers are retired quite out of sight, except here 
 and there one, who saunters about among six hundred or a 
 thousand of the labourers, but never touches the mortar either to 
 lift or carry it; one, in particular, places himself close to the 
 wall they are building. 
 
 67. This soldier will turn himself leisurely on all sides, and 
 every now and then, at intervals of a minute or two, lift up his 
 head, and with his forceps beat upon the building, and make the 
 vibrating noise before mentioned ; on which immediately a loud 
 hiss, which appears to come from all the labourers, issues from 
 within side the dome, and all the subterraneous caverns and 
 passages : that it does come from the labourers is very evident, 
 for you will see them all hasten at every such signal, redouble 
 their pace, and work as fast again. 
 
 68. As the most interesting experiments become dull by repe- 
 
 123 
 
THE WHITE ANTS. 
 
 tition or continuance, so the imiformity with which this business 
 is carried on, though so very wonderful, at last satiates the mind. 
 A renewal of the attack, however, instantly changes the scene, 
 and gratifies our curiosity still more. At every stroke v/o hear a 
 loud hiss ; and on the first the labourers run into the many pipes 
 and galleries with which the building is perforated, which they 
 do so quickly that they seem to vanish, for in a few seconds all 
 are gone, and the soldiers rush out as numerous and as vindictive 
 as before. On finding no enemy they return again leisurely into 
 the hill, and very soon after the labourers appear loaded as at 
 first, as active and as sedulous, with soldiers here and there 
 among them, who act just in the same manner, one or other of 
 them giving the signal to hasten the business. Thus the pleasure 
 of seeing them come out to fight or to work alternately may be 
 obtained as often as curiosity excites or time permits ; and it 
 will certainly be found, that the one order never attempts to 
 fight, or the other to work, let the emergency be ever so great. 
 
 69. We meet vast obstacles in examining the interior parts of 
 these tumuli. In the first place the works, for instance, the 
 apartments which surround the royal chamber and the nurseries, 
 and indeed the whole internal fabric, are moist, and consequently 
 the clay is very brittle; they have also so close a connection, that 
 they can only be seen as it were by piecemeal ; for having a 
 kind of geometrical dependence or abutment against each other, 
 the breaking of one arch pulls down two or three. To these 
 obstacles must be added the obstinacy of the soldiers, who fi^ht 
 to the very last, disputing every inch of ground so well as often 
 to drive away the negroes who are without shoes, and make 
 white people bleed plentifully through their stockings. Neither 
 can we let a building stand, so as to get a view of the interior 
 parts without interruption, for while the soldiers are defending 
 the outworks, the labourers keep barricading all the way against 
 ns, stopping up the different galleries and passages, which lead 
 to the various apartments, particularly the royal chamber, all 
 the entrances to which they fill up so artfully as not to let it be 
 distinguishable, while it remains moist ; and externally it has 
 no other appearance than that of a shapeless lump of clay. It is, 
 however, easily found from its situation with respect to the other 
 parts of the building, and by the crowds of labourers and soldiers 
 which surround it, who show their loyalty and fidelity by dying 
 under its walls. The royal chamber, in a large nest, is capacious 
 enough to hold many hundreds of the attendants, besides the 
 royal pair, and you always find it as full of them as it can hold. 
 These faithful subjects never abandon their charge, even in the 
 last distress, for whenever Mr. Smeathman took out the royal 
 124 
 
THEIR LOYALTY. 
 
 chamber from one of the hills, as he often did, and preserved it 
 for some time in a large glass bowl, all the attendants continued 
 running in one direction round the king and queen with the 
 utmost solicitude, some of them stopping in every circuit at the 
 head of the latter, as if to give her something ; when they came to 
 the extremity of the abdomen, they took the eggs from her, 
 carrying them away, and piled them carefully together in some 
 part of the chamber, or in the bowl under, or behind any pieces 
 of broken clay, which lay most convenient for the purpose. 
 
 Some of these unhappy little creatures would ramble from the 
 chamber as if to explore the cause of such a horrid ruin and 
 catastrophe to their immense buildings, as it must appear to 
 them ; and after fruitless endeavours to get over the side of the 
 bowl, return and mix with the crowd that continued running 
 round their common parents to the last. Others, placing themselves 
 along her side, would get hold of the queen's vast matrix with 
 their jaws, and pull with all their strength, so as visibly to lift 
 up the part which they fix at ; but Mr. Smeathman who observed 
 this, was unable to determine whether this pulling was with an 
 intention to remove her body, or to stimulate her to move herself, 
 or for any other purpose. After many ineffectual tugs, they 
 would desist and join in the crowd running round, or assist some 
 of those who are cutting off clay from the external parts of the 
 chamber, or some of the fragments, and moistening it with the 
 juices of their bodies, to begin to work a thin arched shell over 
 the body of the queen, as if to exclude the air, or to hide her 
 from the observation of some enemy. These, if not interrupted, 
 before the next morning, completely cover her, leaving room 
 enough within for great numbers to run about her. 
 
 The king, being very small in proportion to the queen, generally 
 conceals himself under one side of her abdomen, except when he 
 goes up to the queen's head, which he does now and then, but not 
 so frequently as the rest. 
 
 70. If in your attack on the hill you stop short of the royal 
 chamber, and cut down about half of the building, and leave 
 open some thousands of galleries and chambers, they will all be 
 shut up with thin sheets of clay before next morning. If even 
 the whole is pulled down, and the different buildings are thrown 
 in a confused heap of ruins, provided the king and queen are not 
 destroyed or taken away, every interstice between the ruins, at 
 which either cold or wet can possibly enter, will be so covered as 
 to exclude both ; and, if the animals are left undisturbed, in 
 about a year, they will raise the building to near its pristine siz€ 
 and grandeur. 
 
 71. The marching Termites are not less curious in their order 
 
 125 
 
THE WHITE ANTS. 
 
 than those described before. This species seems much scarcer 
 and larger than the Termes hellicosus. They are little known to 
 the natives. Smeathman had an opportunity of observing them 
 by mere accident ; one day, having made an excursion with his 
 gun up the river Camerankoes, on his return through the thick 
 forest, while he was sauntering very silently in hopes of finding- 
 some sport, on a sudden he heard a loud hiss, which, on account 
 of the many serpents in these countries, is a most alarming- 
 sound. The next step caused a repetition of the noise, which he 
 soon recognised, and was rather surprised, seeing no covered ways 
 or hills. The noise, however, led him a few paces from th-^ path, 
 where, to his great astonishment and pleasure, he saw an army of 
 Termites coming out of a hole in the ground, which could not be 
 above four or five inches wide. They came out in vast numbers, 
 moving forward as fast seemingly as it was possible for them 
 to march. In less than a yard from this place they divided 
 into two streams or columns, composed chiefly of labourers, 
 twelve or fifteen abreast, and crowded as close after one another 
 as sheep in a drove, going straight forward, without deviating to 
 the right or the left. Among these, here and there, one of the 
 soldiers was to be seen, trudging along with them in the same 
 manner, neither stopping nor turning; and as he carried his 
 enormous large head with apparent difficulty, he appeared like a 
 very large ox amongst a fiock of sheep. While these were 
 bustling along, a great many soldiers were to be seen spread 
 about on both sides of the two lines of march, some a foot or two 
 distant, standing still or sauntering about as if upon the look-out 
 lest some enemy should suddenly come upon the workers. But 
 the most extraordinary part of this march was the conduct of 
 some others of the soldiers, who, having mounted the plants 
 which grow thinly here and there in the thick shade, had placed 
 themselves upon the points of the leaves, which were elevated ten 
 or fifteen inches above the ground, and hung over the army 
 marching below. Every now and then one or other of them beat 
 with his forceps upon the leaf, and made the same sort of ticking 
 noise, which he had so frequently observed to be made by the 
 soldier who acts the part of surveyor or superintendent, when the 
 labourers are at work repairing a breach made in one of the 
 common hills of the Termites bellicosi. This signal among the 
 marching white ants produced a similar effect ; for whenever it 
 was made, the whole army returned a hiss, and obeyed the signal 
 by increasing their pace with the utmost hurry. The soldiers 
 who had mounted aloft, and gave these signals, sat quite still 
 during the interval (except making now and then a slight turn 
 of the head), and seemed as solicitous to keep their posts as 
 126 
 
THE MARCHING TERMITES. 
 
 regular sentinels. Tlie two columns of the army joined into one 
 about twelve or fifteen paces from their separation, having in no 
 part been above three yards asunder, and then descended into the 
 earth by two or three holes. They continued marching by him 
 for above an hour that he stood admiring them, and seemed 
 neither to increase nor diminish their numbers, the soldiers only 
 excepted, who quitted the line of march, and placed themselves 
 at different distances on each side of the two columns ; for they 
 appeared much more numerous before he quitted the spot. Not- 
 expecting to see any change in their march, and being pinched 
 for time, the tide being nearly up, and his departure being fixed 
 at high-water, he quitted the scene with some regret, as the 
 observation of a day or two might have afibrded him the oppor- 
 tunity of exploring the reason and necessity of their marching- 
 with such expedition, as well as of discovering their chief settle- 
 ment, which is probably built in the same manner as the large 
 hills before described. If so, it may be larger and more curious, 
 as these insects were at least one-third larger than the other- 
 species, and consequently their buildings must be more wonderful, 
 if possible ; thus much is certain, there must be some fixed place 
 for their king and queen, and the young ones. Of these species 
 he did not see the perfect insect. 
 
 In fine, although the curious and interesting habits and manners- 
 which have been here described have been well ascertained 
 and accurately observed, naturalists are not yet agreed as to 
 the true physiological characters of the most numerous of the 
 classes composing these communities. That the two individuals 
 called the king and queen in the preceding pages, are perfect 
 insects, deprived of their wings, seems to be on all hands, 
 admitted ; and that they are kept for the special purpose of pro- 
 pagation, and honoured as the common parents, is also certain. 
 But the true character of the multitude of workers and soldiers is 
 not so clear. Latreille inferred that the workers of Smeathman 
 consist of the larvae and pupse, which later pass into the perfect 
 state, assuming wings, and swarm in the manner already described; 
 and that the soldiers are an order apart, which never assume the 
 perfect state, and are incapable of reproduction. To this, 
 Burmeister objects, that there is no instance in the whole animal 
 world in which the undeveloped young labour for the old ; and 
 therefore doubts that the workers can be larva? or pupae ; to which 
 may be added, that these so-called larvae stiU retain their form 
 when the winged individuals appear. Huber also doubts that 
 the soldiers can be properly called neuters, and Kirby thinks they 
 
 rJ7 
 
THE WHITE ANTS. 
 
 are probably male larvse. Westwood suggests that the soldiers 
 as well as the workers remain wingless without changing their 
 form, their development stopping short before arriving at maturity, 
 and thereby some individuals acquire that enlarged head which 
 distinguishes the soldiers, and that the real larvaB of the com- 
 paratively few specimens which ultimately become winged, are as 
 yet unknown. 
 
 These vague and discordant conjectures of naturalists so 
 eminent, show how much still remains to be discovered of the 
 physiology of the White Ants, 
 
 128 
 
THE SUREACE OE THE EARTH, 
 
 OR FIRST NOTIONS OF GEOGRAPHY. 
 
 CHAPTER I. 
 
 The Surface op the Earth : 1. Origin of the name. — 2. Preliminary 
 knowledge. — 3. The distribution of land and water, — 4. The undu- 
 lations of the terrestrial surface. — 5. Geographical Terms : 6. 
 Islands. — 7. Continents. — 8. Peninsulas. — 9. Isthmuses. — 10. Pro- 
 montories. — 11. Capes and headlands. — 12. The relief of the land. — 
 13. Plains and lowlands. — 14, Plateaux and table-Ian is. — 15. Hills, — 
 16. Mountains. — 17. Systems or chains of mountains. — 18. Oceans. — 
 19. Seas.— 20. Gulfs.— 21. Bays.— 22. Straits.— 23. Channels.— 24. 
 Roads and roadsteads. — 25. Banks and sand-banks. — 26. Reefs. — 
 27. Soundings.— 28. Lakes.— 29. Rivers.- 30. The bed of a river. — 
 31. The banks of a river.— 32. Tributaries.— 33. Vallies.— 34. 
 Watersheds.— 35. Delta.— 36. Estuaries.— 37. Friths. The Great 
 Eastern Continent : 38. Its extent and limits. — 39. Its divisions. 
 40. The Mediterranean. — 41. Relief. — 42. Its northern belt. — 43. 
 The southern belt, — 44. Prevailing mountain chains. — 45. Outlines 
 of Europe. — 46. White Sea. — 47. Norway and Sweden. — 48. British 
 Isles. — 49. France. — 50. Spain and Portugal. — 51. Italy. — 52. 
 Sicily. — 53. Greece. — 54. Archipelago. — 55. Dardanelles and Bos- 
 phorus.— 56. The Black Sea.— 57. Sea of Azof.— 58. The Caspian. 
 Lardner's Museum of Soienoe. k 129 
 
 No, 109. 
 
THE SURFACE OP THE EAETH. 
 
 — 59. Africa. — 60. Its climatological zones. — 61. The Tell and 
 Sahara.— 62. Valley of the Nile.— 63. The central belt.— 64. The 
 fom-th zone. — 65. The southern zone. — 66. The coasts. 
 
 1. Origin of the name. — The diYision of general instruction to 
 which, the description of the surface of the earth has been con- 
 signed, is called Geographtj, from two Greek words yr^ (ge) the 
 earth, and 7pa<^w (grapho) I describe. 
 
 2. Preliminary knowledge. — The globular form of the earth,. 
 — its rotation every twenty-four hours on its axis, — its poles and 
 equator, the imaginary lines upon it called meridians and parallels, 
 — latitudes and longitudes by which the positions of places 
 •relatively to the equator and to each other are expressed, — the 
 "Snethods of ascertaining these positions for all places, — the divisiom 
 of the globe into the northern and southern hemispheres by the 
 equator, and into the eastern and western hemispheres by the 
 meridian of Greenwich, — have been severally explained in our 
 Tracts on the ''Earth" and on "Latitudes and Longitudes." 
 All these points constitute indispensable preliminaries to any 
 clear or satisfactory knowledge of geography, and we shall there- 
 fore assume in the present Tract that the reader has already 
 become familiar with them. 
 
 3. The distribution of land and water on the surface of 
 the globe forms the jS.rst step in geographical knowledge. The 
 entire terrestrial surface measures about two hundred millions of 
 square miles. Yery nearly three-fourths of this is covered with 
 water. The whole surface would be so if it were uniformly level. 
 But being unequal, some parts being more elevated, and others 
 less so, the water, in obedience to the law of gravity, settles upon, 
 the lower levels, leaving the more elevated parts dry. It is thus 
 that the Almighty has " gathered the waters into one place," and 
 made "the dry land appear," and to the " gathering of waters" 
 has given the name Seas, 
 
 Land is therefore nothing more than the summits and elevaled 
 plateaux of vast mountains, the bases of which are at the bottom 
 of the water which thus covers three-fourths of the surface. 
 
 4. The undulations of the terrestrial surface are extremely 
 diversified and irregular, and since the distribution and outlines 
 of the land are determined by them, the latter are equally 
 various and complicated. The declivities by which these elevated 
 parts slope downwards, determine the lines according to which the 
 waters of the sea wash them, and these outlines give those 
 peculiar forms and characters to the land, the description and 
 knowledge of which forms a large part of geography. A system 
 of terms has been invented by which these various forms are- 
 expressed and classified. 
 
 130 ' 
 
ISLANDS AND CONTINENTS. 
 
 5. Geographical Terms. — Although, these terms do not 
 always admit of rigorous definition, and their application is 
 often more or less arbitrary, they are nevertheless eminently 
 useful, and indeed essential to the acquisition of a general 
 knowledge of geography. 
 
 6. Islands are tracts of land surrounded by water. The term, 
 however, is generally limited to tracts of not very considerable 
 extent. When very small they are often called isles or islets. 
 
 The distribution of islands is not uniform. In some parts they 
 are thickly clustered together within a limited extent of water. 
 A part of the sea thus sprinkled with islands is called an archi- 
 pelago,* a name which was first applied to the ^gsean Sea, which 
 separates Greece from Asia Minor, but which has been generalised 
 so as to signify any portion of the waters of the globe having a 
 like character. 
 
 Islands are found for the most part in the immediate vicinitj^ 
 of the coasts of much larger tracts of land. In this case they are 
 evidently parts of such tracts, separated from them only by 
 valleys, so low that the sea fl.ows through them. Islands, how- 
 ever, are also sometimes found in groups, sometimes ranged in 
 lines, and sometimes, though not frequently, rising singly and 
 isolated in the midst of the ocean. 
 
 7. Continents are tracts surrounded by water, whose magni- 
 tude bears a considerable proportion to the entire surface of the 
 globe. 
 
 It will be easily understood that this distinction between 
 islands and continents, depending only on their comparative 
 magnitudes, must be arbitrary, so long as no exact limit is 
 assigned at which a tract of land surrounded by water ceases to 
 be an island and becomes a continent. , 
 
 The tract in the southern hemisphere, called Australia, was 
 formerly classed as an island. More recently geographers give it 
 the title of a continent. 
 
 Besides this, there are only two continents properly so called on 
 the globe, each of which has vast magnitude, the one lying in the 
 eastern, and the other in the western hemisphere. 
 
 The Eastern Continent, sometimes called the great con- 
 tinent, includes Europe, Asia, and Africa, each of which has re- 
 ceived the name of continent, though the whole forms one continuous 
 tract of land, between any two points of which it is possible to 
 pass without crossing a sea. 
 
 * Etymologists are not agreed upon the origin of this term ; some sup- 
 posing it to be composed of apxi>s (archos), chief, and ireAayos (pelagos), 
 a sea, and others of Aiyaios (aigaios) and ir^Aayos, the ^gsean Sea. 
 
 K 2 131 
 
THE SURFACE OF THE EAETH. 
 
 The Western or lesser continent consists of North and South 
 America. 
 
 The great or eastern continent, having heen known to the 
 ancients, is often called the Old Continent or the Old World. 
 
 The western, having heen unknown until its discovery by 
 Columbus in the fifteenth century, is often called the Neio 
 World, 
 
 8. Peninsulas are tracts, nearly, but not altogether, surrounded 
 by water. The name is composed of two Latin words, pene, 
 almost, and insula^ an island. 
 
 9. Isthmuses are narrow necks, by which two comparatively 
 large tracts are connected together. Isthmus is a Greek word, 
 having the same signification. 
 
 The most remarkable examples of an isthmus are presented by 
 tlie narrow tracts by which Africa is connected with Asia, and 
 South with North America. The former being called the Isthmus 
 of Suez, and the latter the Isthmus of Panama. Two towns, 
 bearing these names, are built, one upon the former isthmus, on 
 the coast of the Red Sea, and the other upon the latter, on the 
 coast of the Pacific Ocean. 
 
 Peninsulas are often thus connected by an isthmus with the 
 mainlands, to which they belong, but not always so. The name 
 peninsula is given to tracts of land which, though partially sur- 
 rounded by water, are nevertheless connected with the mainland 
 by tracts much too broad to be entitled to the name of isthmus. 
 Examples of this class of peninsular form are numerous, and 
 among them may be mentioned the part of Southern Europe, 
 which includes Spain and Portugal, called the Spanish Peninsula 
 (Map 5.) ; the part of Italy, south of Lombardy and Piedmont, 
 called the Italian Peninsula : the southern part of Greece, called 
 the Hellenic Peninsula (Map 6) ; India, and numerous other 
 similar masses of land, projecting in a pointed form into the sea 
 (Map 7). 
 
 10. Promontory is a name given to a tract of land, of greater 
 or less elevation above the level of the sea, which juts out from a 
 comparatively large extent of land, and which therefore is" 
 peninsular in its form. The term, however, is usually applied to 
 tracts of less extent than those which are denominated peninsulas. 
 
 11. Capes and Headlands are promontories having consider- 
 able elevation, so as to be visible from a great distance at sea. 
 
 12. The Relief of the Land has received difi'erent deno- 
 minations according to its varying elevation above the general 
 level'. 
 
 13. Plains and Lowlands are parts of the land not much 
 raised above the level of the sea, having considerable extent. 
 
 132 
 
PLAINS AND MOUNTAINS. 
 
 Various names are given to such tracts according to tne language 
 of the country and their condition in respect to vegetation. Thus 
 an extensive sandy plain, destitute of all vegetation, is called a 
 Desert ; an example of such a plain on an immense scale is pre- 
 sented by the Desert of Sahara, in the North of Africa. Such 
 plains are called Landes in France, Steppes in Russia, and 
 Llanos, Pampas, Selvas, Savannahs, and Prairies, according as 
 they are more or less covered with vegetation, in North and South 
 America. 
 
 Fig. 1.— Forms of Plateaux, Hills and Mountains. 
 
 14. Plateaux and Tablelands are extensive level tracts, 
 .placed at considerable elevations above the level of the sea, or 
 the general level of the surrounding country, a b, fig. 1. 
 
 15. Bills are elevations not exceeding about 1000 feet in 
 height above the plain at their base, and having an outline 
 variously formed ; rounded, e, fig. 1. ; ridged, d, fig. 1, or peaked, 
 as c, fig. 1, and fig. 3. 
 
 Fig. 2. — Groups of Mountains. 
 
 16. Mountains are elevations generally exceeding 1000 feet 
 in height, and likewise subject to a similar variety of forms, 
 as shown in fig. 2. 
 
 The application of these terms hills" and " mountains" is very 
 arbitrary, elevations which receive the name of mountains in one 
 place being lower than those called hills in another. 
 
 The forms of mountains are very various, and have an im- 
 portant relation to their external structure. Geologists are often 
 able to determine the character of the rocks of which they consist 
 by their outline. Thus, when the outline is characterised by 
 needles rising to considerable elevations, as in fig. 4. the moun- 
 tainous mass consists of the rocks called Gneiss. Such peaks, 
 which are frequent upon the chain of the Alps, are called needles, 
 teeth, and horns. Mountains are sometimes columnar in their 
 
 133 
 
THE SURFACE OF THE EARTH. 
 
 structure, as in fig. 5, resembling fortifications seen from a 
 distance. In this case they are usually formed of calcareous, that 
 is, limestone rocks. Mountains composed of the same rocks also 
 
 Fig. ?j. Fig 4. Fig. T). Fig. 6. 
 
 Various forms of Mountains. 
 
 frequently assume the form shown in fig. 6, as if they were cut 
 into steps forming a series of horizontal stages one above the 
 other. 
 
 Mountains which assume the peaked or conical form, with a 
 cavity or cup-like depression at their summits, are always of 
 volcanic origin. 
 
 Fig. 7.— Bai-ren Island in Bay of Bengal. 
 
 In fig. 7, an example of this is presented in the case of Barren 
 island in the Bay of Bengal, consisting of a volcanic cone, 1848 
 feet high, which is frequently in a state of eruption, surrounded 
 by other peaks of similar formation. 
 
 17. Systems or Chains of Mountains consist of series of 
 mountains, of varying elevation and form, which are often con- 
 tinued over the whole extent of a continent. 
 
 18. Oceans. — The configuration of the sea, determined by the 
 form of the lines in [which it unites with the land, necessarily 
 Corresponds with the configuration of the land, and such forms 
 are expressed by a system of geographical terms of correlative 
 signification. 
 
 What a continent is to the land an ocean is to the water. This 
 term, therefore, signifies a vast tract of water, unbroken, for the 
 most part, by anv tract of land. 
 134 
 
OCEANS AND SEAS. 
 
 Owing to th.e peculiar distribution of land and water on the 
 ,^lobe, it follows that, strictly speaking, there is but one great 
 ocean, between all points of which there is a continuous water 
 communication. Nevertheless, geographers have found it con- 
 venient to divide this vast collection of water nominally into 
 several distinct oceans, as will be explained hereafter, 
 
 19. Seas. — The term sea is applied to tracts of water one 
 degree inferior in magnitude to the oceans, which are generally 
 limited and enclosed between continents or large islands. 
 
 20. Gulfs are large inlets of the sea partially enclosed by land. 
 
 21. Bays are nearly the same as gulfs, but generally smaller. 
 Like other geographical terms, these however are arbitrary and 
 indefinite, some inlets called bays being greater than others 
 -called gulfs. 
 
 Glulfs and bays are the analogues of peninsulas and promontories. 
 
 22. Straits are narrow necks of water connecting tracts of 
 greater extent. A strait is, therefore, the analogue of an isthmus. 
 
 A strait is often but improperly called by the plural term 
 straits ; thus the Strait of Gribraltar is freq[uently denominated 
 the Straits of Gibraltar. 
 
 23. Channels are narrow tracts of water flowing between 
 opposite coasts that are nearly parallel, and are much wider than 
 straits. 
 
 24. Roads and Roadsteads are tracts of water sheltered by 
 ^adjacent lands from violent or dangerous winds, having sufficient 
 depth for safety, and not too great depth for anchorage. They are 
 stations where vessels are accustomed to lie at anchor. 
 
 25. Banks and Sandbanks are parts of the bottom which lie 
 so near the surface as to be attended with danger, and in places 
 much affected by tides are often uncovered at low water. 
 
 26. Reefs are sunken rocks, which rise so near the surface, 
 that the waves in passing over them are broken into foam, 
 which thus render their presence manifest to mariners. In a 
 -calm sea, however, as there is nothing to indicate their presence, 
 they are a great source of danger to the navigator. 
 
 27. Soundings. — The depth of the sea is found by a sounding- 
 line, which is a cord of sufficient length, to the extremity of 
 which a heavy piece of lead is attached. Upon this cord knots 
 are made at intervals of five fathoms, the number of knots counting 
 from the lead being indicated by visible marks. The lead is 
 let down into the sea from the deck of the ship ; the sounding- 
 line to which it is attached being coiled round a cylinder, or 
 reel, which turns freely on an axle. Two seamen hold up the 
 reel by handles at the extremity of the axle, while another 
 observes the line passing over the bulwark of the vessel. The 
 
 135 
 
THE SURFACE OF THE EAETH. 
 
 leaden weight sinking in the water draws with it the line, which 
 thus unrolls itself from the reel, and this continues until the lead 
 strikes the bottom. When that takes place the reel ceases to 
 revolve and the line to sink, and the seaman who observes the 
 sounding, notes the number of the knot which is nearest the 
 surface, and thus obtains the depth, which is always expressed in 
 fathoms. 
 
 The lead, suspended from the extremity of the sounding-line, 
 is cup-shaped at its lower end, and grease, technically named the 
 arming, is put into the cavity, so as to be capable of taking up 
 by adhesion a portion of the shells, sand, or other substance, which 
 is at the bottom, with which it comes into contact. This being 
 drawn up, the navigator is informed not only of the depth, but 
 of the quality and character of the bottom, which often serves 
 him as a guide to his position. 
 
 In this manner surveys are made of the bottoms of all seas 
 which are much navigated, and charts are drawn and engraved, 
 upon each part of which is marked the number of fathoms of 
 depth in the corresponding parts of the sea, and frequently the 
 character of the bottom. 
 
 It happens fortunately that the general depth of the oceans and 
 open seas is so considerable as to be attended with no danger to 
 navigation. Such charts, therefore, as are here described are 
 only necessary for navigation in enclosed seas and tracts of water 
 near to coasts. 
 
 28. takes are sheets of water, of greater or less magnitude, 
 completely surrounded by land, and having no superficial com- 
 munication with the sea. They are, therefore, to the water what 
 an island is to the land, and, like an island, the name is generally 
 restricted to magnitudes which are not very great. A lake of great 
 magnitude is generally called an inland sea. 
 
 Like other geographical terms, these, however, are arbitrary ; 
 some sheets of inland water called seas being less than others 
 called lakes. 
 
 29. Rivers are large streams of fresh-water, formed by the rain 
 which falls on elevated parts of the land, descending the de- 
 clivities in streams, which, gradually uniting one with another, 
 form at length a large course of water, which receives the name of 
 a river. 
 
 30. The Bed of a River is a groove formed in the land, de- 
 scending in a direction varying with the level of the surface, 
 until it reaches the coast, where its water is discharged into 
 the sea. 
 
 31. The Banks of a River are the land which confines its 
 course on either side, and are distinguished as the right and left 
 
 136 
 
LAKES AND EIYEBS. 
 
 banks, that which, is to the right in descending the river, being 
 called the right hank, and the other the left bank. 
 
 32. Tributaries, or affluents, are the streams which flow into 
 a river on one side or other of its course. In the larger rivers 
 these tributaries themselves are often considerable rivers, and 
 receive along their course subordinate tributaries. 
 
 By reason of the common tendency of water to find the lowest 
 level, rivers flow along the bottoms of valleys, and their winding 
 courses, often very complicated, are determined by the varying 
 direction of these valleys. Their tributaries run along the 
 bottoms of smaller valleys, intersecting that of the principal river 
 at various angles. 
 
 33. The Valley, along the bottom of which a great river flows, 
 usually receives its name from that of the river, and is often of 
 vast extent; the declivities which form its sides sometimes 
 measuring hundreds, or even thousands, of miles. 
 
 34. Watershed is the name given to the declivities which 
 thus determine the tributaries of a great river, and the whole 
 extent of the valley is sometimes called the basin or hydrographic 
 region of the river. 
 
 35. Delta. — A great river, in approaching its mouth, often 
 diverges into difierent channels, forming angles with each other, 
 and thus discharges itself into the sea by two or more mouths. 
 These diverging branches are called a delta, from a fancied 
 resemblance, presented by the two extreme branches and the 
 line joining the two extreme mouths, to the Greek letter A, 
 delta. 
 
 36. Estuaries. — The mouths of rivers are often placed in inlets 
 of the sea, where the tide ebbs and flows, so that the waters of 
 the sea alternately enter the mouth of the river and retire from 
 it with the rise and fall of the tide, mixing with the water of the 
 river, and thereby producing a constant state of agitation in the 
 water of such an inlet. The name estuary has accordingly been 
 given to such sheets of water, from the Latin word esstus, signify- 
 ing the agitation of water such as that here described. 
 
 37. Firths. — The name firth, also written frith, is some- 
 times given to estuaries ; this term, however, is more particularly 
 applied in Scotland. Thus the estuary of the river Forth, which 
 lies between Fifeshire and Edinburgh, is called the Firth of 
 Forth. 
 
 The term firth or frith is generally assumed to be taken from 
 the Latin word /return, a strait or narrow neck of the sea. 
 Mr. A. K. Johnson, however, considers it to be derived from the 
 Scandinavian term fiord, pronounced fiurth, which has the same 
 signification. 
 
 137 
 
THE SURFACE OF THE EARTH. 
 
 The principal terms composing tlie geographical nomenclature, 
 
 and expressing the forms affected by the outlines of land and 
 waters, and the forms of relief produced by the varying elevation 
 and depression of the surface of the land, being clearly under- 
 stood, a general description of the globe we inhabit, as it is 
 diversified by land and water, and by the undulating surface of 
 the former, will be easily rendered intelligible. 
 
 II. — ARABIA AND PERSIA. 
 
 THE GREAT EASTERN CONTINENT. 
 
 38. Its extent and limits.— This vast tract has an oblong 
 form, as already indicated ; its extreme length being somewhat 
 more than twice its extreme breadth. It is included between 20° 
 west and 190° east longitude, and between 35° south and 75' 
 north latitude. Nearly its whole extent lies therefore in the 
 northern part of the eastern hemisphere. A small portion of the 
 north-western part of Africa, including Morocco, juts into the 
 western hemisphere, and the southern promontory of the same 
 division of the great continent, terminating in the Cape of Good 
 Hope, projects into the southern hemisphere. 
 
 This continuous tract of land consists, as is well known, of three 
 unequal divisions, which, though not detached one from another 
 by sea, have received the name of continents. The smallest of 
 138 
 
THE GREAT EASTERN CONTINENT. 
 
 these in magnitude, but transcendently the most important in 
 its social and political character, is Eueope, which occupies the 
 northwest corner of the great continent, being separated from 
 Africa by the Mediterranean Sea, and from Asia by a low chain 
 of mountains called the Ural, a river of the same name, the 
 Caspian Sea, a great sheet of inland water, into which this river 
 discharges itself, and the Black Sea. 
 
 39. Its divisions. — If the whole superficial extent of the 
 great continent be supposed to consist of eight equal parts, the 
 area of Europe will be one of these parts, that of Africa three, and 
 that of Asia, which covers the remainder, four. 
 
 Africa is divided from Europe by the Mediterranean Sea, and 
 from Asia by the oblong tract of water, directed N.N."W. and 
 S.S.E., called the Eed Sea. This sea is connected with the 
 Indian Ocean, lying to the east of Africa, and the south of Asia, 
 by a narrow neck of water, called the Strait of Bab-el-Mandeb. 
 
 40. The Mediterranean sea, which forms one of the most im- 
 portant features in the westerii part of the great continent, lies in 
 a direction nearly east and west, and communicates with the 
 Atlantic Ocean by a narrow neck of water, interposed between the 
 southern point of the Spanish peninsula, and the north-western 
 corner of Africa, called the Strait of Gibraltar, from the rock 
 of that name at the point of Spain. 
 
 41. Relief. — The relief of the surface of the great continent is 
 characterised by an elevated ridge, the general direction of which 
 is parallel to its longitudinal axis, and is consequently E.N.E. 
 and W.S.W. very nearly, but the summit of this ridge is much 
 nearer to the southern than to the northern coast of the continent, 
 so that it divides its area very unequally. The declivity, therefore, 
 which slopes to the southern coast, is much more rapid and 
 shorter than that which extends to the northern coast. 
 
 42. Its northern belt. — The northern division consists of a 
 great belt of flat surface, beginning with the plains of Holland 
 at the west, and terminating with the deserts of Siberia at the 
 oast, being only interrupted by the chain of Ural Mountains, 
 running north and south at the confines of Europe and Asia. 
 Except where human industry has redeemed it, and brought it 
 under cultivation near its western extremity, the characteristic 
 of this plain is that of marshiness and insalubrity. 
 
 43. The southern belt.— The more limited plain south of the 
 ridge- summit, alreadj^ mentioned, commences at the west with the 
 great African desert of Sahara, and stretches with little inter- 
 ruption across Arabia, Persia, and Northern India, to the shores 
 of Kamtschatka. 
 
 44. Prevailing mountain - chains. — The various mountain- 
 
 139 
 
THE SURFACE OF THE EARTH. 
 
 eLains, the combination of which forms the main ridge of the 
 great continent, commence with Mount Atlas and the Pyrennees 
 at the extreme west, and are continued by the Alps and the 
 Himalaya to the Altaic mountains at the extreme east. 
 
 45. Outlines of Europe; their adaptation to Commerce. — 
 The most striking geographical feature by which Europe is 
 distinguished from the other parts of the great continent, consists 
 in the numerous and extensive inlets of water by which it is 
 penetrated and intersected in all directions. No equal extent of 
 land in any part of the globe presents a like phenomenon, and to 
 this, as much as to its temperate climate, must undoubtedly be 
 ascribed the immense social, commercial, and political predo- 
 minance which it has acquired and maintained. By this reticu- 
 lation of inland seas, gulfs, bays, and straits, navigation and 
 commerce arrive within short distances of all its internal centres, 
 and its vast extent of coasts is studded with cities and towns, 
 and sheltered ports and harbours, which become so many em- 
 poriums of commerce, and centres and sources of wealth and 
 civilisation. 
 
 46. White Sea. — At its extreme north, Europe is penetrated 
 by an enclosed sheet of water of great magnitude, called the White 
 Sea. On the west, the Baltic enters it, ramifying in different 
 directions, throwing out north and west the gulfs of Bothnia and 
 Finland, and sprinkled with islands and vast peninsulas, which 
 form kingdoms of great importance, such as Denmark. 
 
 47. Norway and Sweden are formed into a great peninsula, 
 separated from the continent by a broad neck of land, included 
 between the North Sea on the west, and the head of the Gulf of 
 Bothnia on the east. 
 
 48. British Isles.— Nearly opposite the mouth of the Baltic, 
 and the north-western point of France, are placed the British 
 Isles, separated from the coast of Holland and Belgium by the 
 German Ocean, and from that of France by the English Channel 
 and the Strait of Dover. These islands, combined with the sub- 
 ordinate ones with which they are surrounded and skirted, such 
 as the Shetlands, the Orkneys, the Western Isles, the Isles of 
 Man and Anglesea, the Scilly, and the Channel Islands, may be 
 considered as forming an archipelago, the principal divisions of 
 which are richly intersected by channels, bays, and gulfs, which 
 have so favoured navigation, as to enable the British nation to 
 attain and maintain that commercial and naval pre-eminence, 
 for which she has so long been celebrated. 
 
 49. Trance, the most important and powerful of the European 
 states, occupies the centre of Western Europe. Her territory is se- 
 parated on the east from those of the German states by the Rhine, 
 
 140 
 
THE DIVISIONS OF EUKOPE. 
 
 from that of Switzerland by the chain of the Jura, from Italy by 
 the Alps, from Africa by the Mediterranean, and from Spain by the 
 Pyrenees. On the west it is limited by the Atlantic, and on the 
 north, in the absence of any natural boundary, is divided from 
 Belgium by a frontier settled by political conventions. 
 
 50. Spain and Portugal occupy a portion of land having the 
 peninsular form, the neck by which it is connected with the con- 
 tinent extending from the Bay of Biscay to the Gulf of Lyons, and 
 being traversed by the chain of the Pyrenees. This neck of 
 land, so much narrower than the general width of the Spanish 
 peninsula, is nevertheless much too wide to entitle it to the name 
 of an isthmus. 
 
 In the geography of Europe the tract thus occupied by Spain 
 and Portugal is usually called the Peninsula, without other 
 designation. 
 
 51. Italy. — The southern part of Italy projects into the 
 Mediterranean Sea in the form of an oblong tract of land, having 
 at its southern extremity a smaller tract nearly at right angles to 
 it ; the outline of the whole presenting a striking resemblance to 
 a boot. The Italian territory, however, occupies a wide extent of 
 land north of the boot, enclosed on the north by the chain of the 
 Alps, This northern part of Italy includes the territories of 
 Venice and the Milanese, called Lombardy, at present part of 
 the Austrian empire, and the kingdom of Sardinia. That part of 
 the Italian territory forming the boot, being nearly surrounded 
 by water, with the Adriatic on one side and the Mediterranean 
 on the other, is distinguished as the Italian Peninsula. 
 
 52. Sicily. — Immediately at the toe of the boot, and separated 
 from it by a narrow neck of water, celebrated in history as the 
 Strait of Messina, is the fertile and beautiful island of Sicily, one 
 of the most remarkable features of which is the volcano called 
 Mount Etna. 
 
 53. Greece projects into the eastern end of the Mediterranean, 
 ha\ing, like Italy and Spain, the peninsular character. These 
 three tracts have been noticed even by ancient geographers as the 
 Spanish, Italian, and Hellenic peninsulas. 
 
 54. Archipelago. — The arm of the Mediterranean which, 
 turcing to the north, intervenes between the Hellenic peninsula 
 and the coast of Asia Minor, thickly sprinkled with islands, is the 
 Archipelago or ancient ^gsean Sea, from which all other tracts 
 of water of a similar character have taken their name. 
 
 55. Dardanelles and Bosphorus. — The Archipelago is con- 
 nected with the great inland sea, called the Black Sea or the 
 Euxine, by a narrow neck of water, consisting of two straits, 
 between which lies a wider strip of sea. The strait which is next 
 
 141 
 
THE SUEFACE OF THE EARTH. 
 
 the Archipelago is called the Dardanelles, the ancieat Hellespont ; 
 and that which is next the Black Sea, the Bosphorus ; the inter- 
 mediate water being called the Sea of Marmora. 
 
 56. The Black Sea is nearly enclosed by land, but com- 
 municating through the Bosphorus with the Archipelago and 
 the Mediterranean, it cannot properly be considered as a lake. 
 Its water is, nevertheless, much less salt than that of the ocean, 
 and it is consequently more readily frozen. Its depth near the 
 shore varies from 24 to 220 feet, and in the middle is more than 
 1000 feet. 
 
 57. Sea of Azof. — This sea communicates with a smaller one 
 north of it, called the Sea of Azof, by a narrow neck of water, 
 called the Strait of Tenekali. A tract of land nearly surrounded 
 by the waters of the Black Sea and the Sea of Azof, and connected 
 with the continent by a narrow neck of land, is called the Crimea;, 
 the connecting neck being called the Isthmus of Perikop. This 
 peninsula has been celebrated for the fortress of Sebastopol erected 
 by Russia near its southern extremity, and destroyed in 1855 by 
 the allied armies of France and England. 
 
 58. The Caspian. — Near the southern confines of Europe and 
 Asia is the largest lake in the world, called the Caspian Sea. Its 
 water is salt, but much less so than the ocean, and it is shallow, 
 even at its centre, the depth not exceeding 300 feet. That it can, 
 have no immediate and uninterrupted subterranean communication 
 with the Black Sea, which is near it, is proved by the fact that 
 the level of its surface is 82 feet below that of the latter sea. 
 
 59. Africa is an immense triangular- shaped tract of land, the 
 base of which is presented towards the north, and the point to the 
 south. Its coast is everywhere nearly uniform, and entirely 
 destitute of those indentations for which Europe is so remarkable. 
 It projects southwards into the great ocean, which it divides into 
 two regions, of which the western is called the Atlantic, and the 
 eastern the Indian Ocean. As has been already stated, Africa is 
 separated from Asia by the Red Sea, except at the point where 
 they are connected by the narrow isthmus of Suez. 
 
 This division of the great continent is, beyond all comparison, 
 the most uncivilised and desert portion of the globe. It includes 
 a vast range of country, extending from the northern to the 
 southern tropic, and lying, therefore, altogether in the torrid zone. 
 By reason of the great extent of desert of which it consists, the 
 insalubrity of its climate, and the barbarous character of its 
 inhabitants, it is little known to Europeans. 
 
 60. Its Climatological Zones. — It may be considered as con- 
 sisting of a succession of zones, separated by parallels of latitude, 
 having different physical characters. 
 
 142 
 
AFRICA. 
 
 61. The Teil and Sahara. — The northern zone, included be- 
 tween the ridge of Mount Atlas and the Mediterranean, is a band 
 of fertile country, generally called the Tell, probably from the 
 Latin word tellus, the earth. South of this is a vast band^ 
 running east and west, about 1800 miles broad, comprising Sahara 
 or the great desert. This extensive surface consists of tracts of 
 sandy and stony soil, rarely producing vegetation, and, when it 
 does, of the most scanty description, with the exception of certain 
 spots appearing here and there in this ocean of desolation, like 
 islands of fertility. These are called Oases, and depend for their 
 productiveness on local springs. 
 
 62. Valley of the Hile. — On the west this desert not only 
 descends to the verge of the ocean, but is continued with the same 
 character for many miles beneath its surface and beyond the 
 coast. On the east, it descends by a series of sterile terraces 
 to the valley of the Nile, where the soil suddenly acquires 
 a high degree of fertility, which character it retains throughout 
 the whole extent of country between the Nile and the Eed Sea.- 
 The entire valley of the Nile, from the skirt of the Desert to the 
 Delta, and from the right bank of the river to the Eed Sea, has 
 been celebrated in ancient history for its general fertility, a 
 character, nevertheless, which is not altogether without exception, 
 an example of which is presented in the tract over which the- 
 route between Cairo and Suez is conducted. 
 
 63. The central Belt of Africa, immediately south of the 
 great desert, has quite a different character, being both fertile 
 and populous. 
 
 64. The fourth zone, lying south of this, is almost unknown, 
 except on its seaboard. It is supposed to consist of an extensive 
 and elevated table-land, with lofty mountain-ranges rising out 
 of it, from which character it is distinguished in geography as 
 High Africa. 
 
 65. The southern zone of the great African peninsula con- 
 sists of a triangular area, the vertex of which projects into the 
 Southern Ocean, and is terminated by the celebrated Cape of 
 Good Hope. This part is diversified by hill and valley, and is 
 naturally fertile, supplying extensive pasturages. The native 
 tribes which inhabit it are the Hottentots and Caffres. The 
 English colony, originally Dutch, has been generally confined to 
 the southernmost part of the angle, but has a constant tendency 
 to push their territory further north, thereby coming into contact, 
 and frequently into conflict, with the natives. 
 
 66. The coasts. — It has been already observed that the coasts 
 of Africa are singularly destitute of all projections and indent- 
 ations, and, consequently, ill-adapted for commerce. For the 
 
 143 
 
THE SURFACE OF THE EAllTH. 
 
 same reason, there is a remarkable absence of those numerous 
 islands which enrich all coasts deeply indented, which considered 
 in their physical character are in fact parts of the mainland, 
 separated from it by valleys so deep as to allow the sea to 
 flow through them. Madagascar, on the east coast, is the only 
 African island. There are a few islands of much less magnitude, 
 called the Comano Islands, between Madagascar and the coast. 
 Most of the other islands which appear in the Indian Ocean a,re 
 too distant to be regarded as mere appendages of Africa. 
 
 148 
 
III.— AUSTRALASIA. 
 
 THE SURFACE OF THE EAUTH, 
 
 OR FIRST NOTIONS OF OEOGRAPHT. 
 
 CHAPTEE IT. 
 
 67. Asia.— 68. Its Plateaux.— 69. The eastern Plateau.— 70. Its physical 
 character. — 71. The western tableland. — 72. British India : Dekkan 
 plateau. — 73. Australia, — 74. Australasia. — 75. Polynesia. — 76. 
 British Colony : its territory and physical features. — 77. Its climate. 
 — 78. Vegetable productions. — 79. The indigenous animals. — 80. 
 Minerals: Grold.— 81. Aboriginal tribes. The Westekn,^ or 
 New Continent. — 82. Its extent and form. — 83. Divisions: 
 South America. — 84. Central America. — 85. North America. 
 — 86. Its extent and limits. — 87. Its political divisions. — 88. 
 Gulf of Mexico and Caribbean Sea. — 89. Relation between the coasts 
 of the old and new continents.— 90. The relief.— 91. Ohippev/ayau 
 Lardner's Museum of Science. l 145 
 
 No. 111. 
 
THE SURFACE OF THE EARTH. 
 
 and Rocky Mountains. — 92. Cordilleras and Andes, — 93. Andes of 
 Patagonia and CMli. — 94. Andes of Bolivia and Peru. — 95. Cordil- 
 leras. — 96. Potosi. — 97. Pampas of Patagonia and Buenos Ayres. — 
 98. Selvas of the Amazon. — 99. Llanos of Orinoco. — 100. Alleghanies. 
 — 101. Eastern plain of North America. — 102. Great valley of the 
 Mississippi. — 103. The Prairies. — Outlines of the land. — 104. The 
 prevalence of the peninsular form. — 105. The South American penin- 
 sula. — 106. The North American peninsula. — 107. The West Indian 
 archipelago. — 108. The peninsula of Florida. — 109. Lower California. 
 — 110. Greenland. — 111. Africa. — 112. Australia. — 113. New Zea- 
 land. — 114. Similar tendency in smaller regions. — 115. The Spanish 
 peninsula. — 116. The Italian peninsula. — 117. The Hellenic penin- 
 sula. — 118. The Crimea. — 119. The Scandinavian peninsula. — 120. 
 European peninsula. — 121. The Indian peninsula. — 122. Further 
 India. — 123. Hemisphere of most land. — Rivers. — 124. Formation 
 of rivers. — 125. Elfect of a single ridge. — 126. Example in the eastern 
 continent. — 127. Example in South America. — 128. Effect of parallel 
 ridges, — 129. Chief tributaries considerable rivers. — 130. Example 
 of Missouri. — 131. Trifling elevation of watershed. — 132. Portage. — 
 133. Examples of rivers in North America. — 134. Eastern rivers. — 
 135. Westei-n rivers. — 136. The Mississippi and its tributaries. — 
 137. Valley of the Mississippi. — 138. Red River, Arkansas, Ohio. — 
 139. St. Louis.— 140. IlUnois. 
 
 67. Asia, constituting in geographical extent fully half the 
 great continent, and occupied by a population numbering half the 
 total amount of the human race, is in many respects an interesting 
 quarter of the globe. It is in immediate geographical continuity 
 with Europe, separated from Egypt only by the narrow strip of 
 vvater called the Red Sea, and connected with it by the isthmus 
 of Suez, and separated on the east from the American continent 
 by the narrow neck of water called Behring Straits. Its eastern 
 coast is fringed with innumerable islands, and indented by large 
 bays and gulfs ; and its southern points are in a certain sense 
 connected with the new continent of Australia by the archi- 
 pelago which intervenes between the Indian and Pacific Oceans, 
 of which the most considerable islands are Sumatra, Borneo, 
 Pappua, and Java. The equator traverses the middle of this 
 archipelago, the whole extent of which is included between 20** 
 of north and 10° of south latitude. 
 
 68. Its plateauK.— The mainland of Asia consists of two ex- 
 tensive plateaux, each of which is limited and intersected by 
 mountain-chains, from which the surface falls by a succession of 
 slopes and terraces to the level of the lowlands. 
 
 69. The eastern plateau, which is the most elevated, includ- 
 ing Thibet and the desert of Gobi or Shamo, has an elevation 
 varying from 4000 to 15000 feet above the level of the sea. 
 
 This great tableland has for its southern limit the Himalaya 
 chain, for its northern the Altai, and the chain called Thian. On 
 146 
 
ASIA. 
 
 the west it is limited by the Bollortagh, and on the east by a 
 chain running directly north from Pekin called the Khingan 
 mountains. 
 
 70. Its physical character. — The physical character of 
 this vast plateau may be in some degree comprehended, when it 
 is stated that it consists of three-fourths of a million of square 
 miles of surface, having a general elevation greater than that of 
 the most lofty mountain-ranges of Europe. 
 
 This plateau descends towards the north by gentle slopes, so 
 as to convert the extensive zone of surface along the northern 
 coast into a vast plain, the general elevation of which above the 
 surface of the sea does not exceed a few hundred feet. 
 
 On the south and south-east sides, the great plateau advancing 
 comparatively close to the coast, the descent is much more rapid. 
 
 71. The western tableland embraces the tract between 
 the Caspian Sea and the Persian Gulf on the north and south, 
 and the river Indus on the east. It does not exceed 4000 feet in 
 elevation, and is generally less. This tract, called the tableland 
 of Iran, the ancient Persia, is now divided into Cabul on the 
 east, and Persia on the west. Stretching in the direction of 
 the north-west to Asia Minor, it slopes gradually down to the 
 archipelago. 
 
 72. British India : Dekkan plateau.— One of the geogra- 
 phical features of this division of the great continent is the tri- 
 angular projection which juts down into the Indian Ocean, and 
 constitutes the chief part of the territory of British India. 
 This also consists of a plateau, of moderate elevation, called the 
 tableland of Dekkan, Between this, which covers the whole 
 extent of the peninsula and the Himalaya mountains which 
 run east and west, is a plain of low elevation, called the plain of 
 Hindoostan, forming the valley along which the Granges, with its 
 tributaries, flows from west to east, forming its delta, and dis- 
 charging itself into the Bay of Bengal, at the northern extremity 
 of that gulf near Calcutta. The western portion of the same 
 plain slopes towards the Arabian Sea, and is the valley similarly 
 drained by the Indus and its tributaries. 
 
 73. Australia, formerly called New Holland, is an insular 
 mass, whose extent and importance are such that it has ceased to 
 be called an island, and is now generally ranked as a continent. 
 It is placed south of the line between latitudes 15° and 40°. 
 l^ear it are several other islands of less magnitude, the prracipal 
 of which is New Zealand. South of it is a smaller island, formerly 
 called Yan Diemen's Land, and now denominated Tasmania. 
 
 74. Australasia, — The group consisting of Australia, Tas- 
 mania, New Zealand, and the smaller islands near them, are 
 
 L 2 147 
 
THE SUEFACE OP THE EARTH. 
 
 called by modem geographers Australasia, being the most con- 
 siderable tracts of land in the southern latitudes. The various 
 islands sprinkled in countless numbers over the Pacific Ocean, 
 comprising Australasia itself, have received the general name of 
 Oceania. 
 
 75. Polynesia. — Those which lie between the Indian Archi- 
 pelago and the western coast of America, taken collectively, have 
 been called Polynesia. 
 
 76. British Colony; its territory and physical features. — 
 From the circumstance of the recent gold discoveries, and the con- 
 sequent emigration from the United Kingdom to Australia, this 
 colony has acquired a greater interest than any which its mere 
 geographical pretensions could claim for it. It may therefore 
 be desirable here to notice its physical character and conditions. 
 
 Notwithstanding the immense immigration which has taken 
 place, and the excitement attending the mineral researches, of 
 which it has become the theatre, the surface of this great island 
 has been but very imperfectly explored. One of the most remark- 
 able and geographical characters it presents is the complete 
 absence of large navigable rivers, and the uniform outline of its 
 coast, which has no indentations forming bays, gulfs, or other 
 inlets. It is surrounded by a chain of mountains, the sum- 
 mit-ridge of which is from 30 to 40 miles from the shore. The 
 chain running along the eastern coast, which is best known, 
 is called the Australian Alps at the extreme south, the Blue 
 Mountains near Sidney, and the Liverpool chain towards the 
 north. From the slopes of these mountains a few small rivers 
 descend, which are so inconsiderable as to be nearly dry in 
 summer. The interior consists of a series of low plains, which 
 include good pasturages, and large tracts covered with sand and 
 sheUs, which have an appearance such as would be presented by 
 a surface from which the sea had recently retired. Some consider- 
 able streams have been seen in the interior, but whether they flow 
 into an inland sea like those which run into the great Asiatic 
 lake, or are absorbed by the sands, has not been ascertained. 
 
 One of the most curious physical characters connected with this 
 island is the existence on its north-eastern coast, at a distance of 
 from 20 to 70 miles, of the longest coral reef in the world, measuring 
 about 1200 miles in length, and rising out of the bosom of a sea 
 said to be fathomless. The breadth of this reef varies from a few 
 hundred yards to several miles. 
 
 77. Its climate. — When it is remembered that the extreme 
 latitudes of Australia are 15° and 40°, it may be expected that its 
 climate must be mild and salubrious. "With a drier atmosphere 
 it has all the thermometric characters of Southern Italy. The 
 
 148 
 
THE WESTEEN, OK NEW CONTINENT. 
 
 vegetation seems to be maintained by the deposition of dew, for 
 it often happens tbat intervals of several years elapse without 
 rain. When rain does occur, however, it is periodic, and prevails 
 through three months. 
 
 78. Vegetable productions. — The natural vegetable pro- 
 ductions are neither considerable nor useful; there is no species 
 of edible fruit. The trees composing the woods appear to be of 
 one uniform family, the foliage being scanty and almost shadow- 
 less. On the other hand, transplanted vegetation is easily natu- 
 ralised. Districts are found adapted to the cultivation of all sorts 
 of grain ; but, for the present, the most advantageous employment 
 of the soil is for pasturage. 
 
 79. The indigenous animals are few, being mostly of the 
 family of marsupia, such as the opossum and kangaroo. The 
 most remarkable and anomalous of these animals is one called 
 the ornithorhynehus, which is a sort of connecting link between 
 birds and quadrupeds, having the bill and feet of a duck, and the 
 body and fur of a mole. 
 
 80. l^inerals — Gold — It is well known that gold in large 
 quantities is found in this region. It may be added, however, 
 that coal and iron also exist there in inexhaustible quantities, as 
 well as marble, lead, and copper. 
 
 81. Aboriginal Tribes. — The native tribes, which appear to 
 prevail in but limited numbers, are in the lowest state to which; 
 nature can sink. They are generally nomadic, but sometimes 
 build rude villages, and subsist by fishing on the coast. 
 
 So utterly degraded is their condition, moral and physical, that 
 many tribes are unprovided with clothing, practise cannibalism, 
 and are wholly destitute of social and religious ideas. 
 
 THE WESTERN, OE NEW CONTINENT. 
 
 82. Its extent and form. — Like the great eastern continent, 
 the western is an oblong tract of land, the length of which inter- 
 sects the parallels of latitude obliquely, being directed first from 
 the,S. S. E. to N. N. W. and then turning eastward in approach- 
 ing the pole. It extends from 50° S. lat. to the utmost limit of 
 polar discovery. 
 
 83. Divisions— South America. — This continent consists of 
 two peninsulas, connected by a narrow tract of considerable 
 length. The southern peninsula resembles Africa in its general 
 outline, having a triangular form, with its base towards the 
 north, and its vertex to the south. It also resembles the African 
 continent in having coasts but little indented by bays or gulfs, 
 
 149 
 
THE SUKFACE OF THE EARTH. 
 
 but differs from it in being intersected by large and extensive 
 rivers. 
 
 84. Central America is the tract of land uniting Soutb America 
 with the northern peninsula. Its southern part being not more 
 than 30 miles wide, is denominated the isthmus of Darien or 
 Panama, a town of the latter name being on its western coast. 
 
 IV. — UNITED STATES—CANADA, 
 
 85. North America, like Europe, is indented with numerous 
 bays, and its northern division has the largest collections of fresh 
 water in the world, consisting of five extensive lakes,— called 
 Superior, Michigan, Huron, Erie, and Ontario, which communi- 
 cate with each other, and discharge their water through the 
 Eiver St. Lawrence into the gulf of that name. 
 
 86. Its extent and limits.— North America is separated from 
 Asia by Behring Strait on the west, and from the large island of 
 Greenland by Bafian's Bay and Davis's Strait on the north ana 
 east. 
 
 A sort of northern archipelago intervenes between this conti- 
 nent and Greenland, into which numerous promontories project, 
 and the waters of which are variously denominated, the largest 
 of these inlets being Hudson's Bay. 
 
 87. Its political divisions.— In political geography North 
 150 
 
AMERICA. 
 
 America consists of several divisions, the central part being tlie 
 United States, the north-eastern British America, the north- 
 western angle near Behring Strait, Eussian America, and the part 
 forming the southern point, Mexico. 
 
 88. Gulf of Mexico and Caribbean Sea.— The large inlet of the 
 ocean enclosed between the northern coast of South America, the 
 southern coast of I^'orth America, and the eastern coast of Mexico 
 and Central America, consists of the Gulf of Mexico and the 
 Caribbean Sea^ its eastern part, sprinkled with the West Indian 
 islands, forming an archipelago. 
 
 89. Relation between the coasts of Old and New Continent. 
 — It has been observed by Humboldt, that on comparing the eastern 
 coast of South America with the western coast of Africa, the 
 same correspondence is observed between them as is usually seen 
 in the opposite sides of a valley or ravine ; from which he argues 
 that the bottom of the Atlantic, which flows between these conti- 
 nents, ought to be regarded as an extensive valley, the sides of 
 which, rising to an elevation above the level of the water which 
 fills it, form the coasts of the two continents. Thus the concavity 
 on the African coast, called the Gulf of Guinea, has a correspond- 
 ing convexity on the South American coast forming the territory 
 of Brazil, and the convexity at the north-western corner of 
 Africa, of which the coast of Morocco forms a part, corresponds 
 with the opposite concavity formed by the Caribbean Sea and the 
 Gulf of Mexico. So that if the two continents were moved 
 towards each other, and brought into contact, their coasts would 
 fit into each other, like the dove-tailed edges of carpentry. The 
 Atlantic, following the course of this submarine valley, entering 
 between the Cape of Good Hope and Cape Horn, flows first in a 
 northerly direction, a little towards the east, next, after passing 
 the Gulf of Guinea, in a north-westerly direction, and finally, 
 after passing the north-western coast of America, in a north- 
 easterly direction. 
 
 90. The relief of the western continent is characterised by a 
 continuous ridge of considerable elevation, which traverses it longi- 
 tudinally from its northern to its southern limit, lying much 
 nearer to the western than to the eastern coast. 
 
 91. ^hippewayan and Rocky Mountains. — The part of this 
 ridge or mountain-chain which traverses North America, com- 
 mencing at the Frozen Ocean, is called in its northern division 
 the Chippewayan range, and in its southern division by the better 
 known name of the Eocky Mountains. 
 
 92. Cordilleras and Andes.— After passing along Central Ame- 
 rica, this ridge takes the name of the Cordilleras and Andes, 
 and rising to much greater heights, and throwing up vast peaks 
 
 151 
 
THE SURFACE OF THE EARTH. 
 
 which, are frequently volcanic, it is continued in a direction 
 parallel to the western coast of the continent, until it terminates 
 in the Tierra del Fuego, the southern point of which is called 
 Cape Horn. 
 
 93. Andes of Patagonia and Chili. — Between this point and 
 Chili, returning northwards, the slopes of the Andes descend to the 
 waters of the Pacific, the coast being lined with numerous islands 
 and indented with arms of the sea, an outline which indicates 
 the continuation of the mountain range below the waters of the 
 ocean; the capes, promontories, and islands being merely the 
 ridges and summits of the spurs and peaks of the main range, 
 whose bases are established at the bottom of the ocean. Pro- 
 ceeding northward, the general direction of the chain takes a 
 more inland course, leaving between its base and the sea a long 
 and flat tract of land, whose coast is no longer broken by the 
 indentations just described, is completely destitute of islands, and 
 forms no shelter for navigators. 
 
 94. Andes of Bolivia and Peru.— StiU proceeding northward 
 and approaching the Peruvian territory, the general elevation of 
 the Andes rapidly increases, and their summits rise to vast 
 elevations above the snow-line ; among these is the Nevado 
 Aconcagua, having an elevation of 24000 feet, and being the most 
 lofty point of the western continent. This peak was originally 
 volcanic, but within historic record it has not been active. 
 
 About latitude 24° south, the chain takes the name of the 
 Peruvian Andes, and here it is at a considerable distance from 
 the western coast, from which it is separated by a sandy 
 desert. 
 
 95. Cordilleras. — North of 21° lat. south, the chain of the Andes 
 diverges into two or three separate ridges, called Cordilleras, 
 which are connected at different points by their common spurs 
 issuing transversely to their directions, so as to form a net- work 
 enclosing numerous valleys, the bottoms of which are elevated to 
 a considerable height above the level of the sea, forming in many 
 cases plateaux and tablelands of great extent, the most remark- 
 able of which is that of Desaguadero, which measures 400 miles 
 in length, with a breadth varying from 30 to 60, and a general 
 elevation of nearly 13000 feet above the level of the sea. Vast 
 peaks are thrown up from the borders of this immense plateau to 
 the height of more than 8000 feet above the surface, rising far 
 above the snow-line. 
 
 96. Potosi.— Upon this extensive tableland, whose area is 
 three times that of Switzerland, stands Potosi, the highest city in 
 the world, at an elevation of 13330 feet above the level of the 
 sea, with a population of 30000. This city is built on the 
 
 152 
 
PAMPAS AJs^D PRAIRIES. 
 
 northern declivity of a mountain called Cerro de Potosi, wliicli is 
 tich. in mineral veins, and especially in silver. 
 
 97. Pampas of Patagonia and Buenos Ayres. — Since, as 
 has been explained, this great chain runs close to the western 
 coast, it may be expected that a vast tract of plains, or lower 
 lands, must extend from the foot of its eastern declivity to 
 the eastern coast of the continent. This tract in South America 
 is covered with the deserts and pampas, as they are called, of 
 Patagonia and Buenos Ayres, the surface of which is sandy and 
 marshy, or saline, producing nothing but a scanty pasture and 
 stunted trees. 
 
 98. Selvas of Amazon. — Another portion, consisting of 
 the valley of the great Eiver Amazon, called Selvas, consists of 
 a space of more than two millions of scjuare miles, a part of which 
 is covered with natural forests, and the remainder with, grassy 
 pampas. 
 
 99. XJanos of Orinoco. — The valley of the Orinoco, another 
 division, is characterised by vast flat lands, called Llanos, 
 covered with long grass, interspersed here and there with palm 
 trees, used by the traveller in these inhospitable regions as land- 
 marks. 
 
 100. AUeghanies.— Extensive lowlands stretch in like manner 
 over North America, between the chain of the Rocky Mountains 
 and the eastern coast. This division of the continent is also inter- 
 sected in a direction parallel to the Rocky Mountains, and nearer 
 to the Atlantic by a chain of much lower hills called the AUeg- 
 hanies, which, like the former, extend from the Gulf of Mexico to 
 the Arctic Ocean, enclosing an area of more than 3,000000 of 
 square miles. 
 
 101. Eastern Plain of North America- — Between the 
 chain of the AUeghanies and the Atlantic coast is another plain 
 parallel to the former, of nearly equal length from north to south, 
 but of less width. The eastern coast is indented and fringed with 
 numerous bays and creeks, which favour commerce and navigation. 
 
 102. Great Valley of the Mississippi.— The extensive vaUey 
 lying between the chain of the AUeghanies and the Rocky Moun- 
 tains is drained by the Mississippi, the largest and most important 
 river in the world, next to the Amazons, which, nevertheless, it 
 exceeds in length, though inferior to it in the extent and number 
 of its tributaries. 
 
 103. The Prairies.— Among the features which characterise 
 the land in the western continent, and more especially in its 
 northern part, the Prairies demand especial notice. These are 
 vast plains, generally covered by deep herbage, and which form a 
 level so dead and uniform, that it is impossible to resist the 
 
 153 
 
THE SURFACE OF THE EARTH. 
 
 impression that they must have been once the bottoms of large 
 sheets of water, since nothing but sedimentary deposition could 
 produce a level so uniform. The extent of many of these plains 
 is so great, that in traversing them points may be attained 
 from which all the surrounding country will cease to be visible, 
 so that the prairie presents to the observer a circular horizon, like 
 that witnessed at sea from the deck of a ship. 
 
 As there are, in general, no roads or paths traversing these vast 
 plains, the traveller who ventures across them can only guide his 
 steps by a compass, or by the stars. 
 
 OUTLINES OF THE LAND. 
 
 104. The prevalence of the peninsular form with the point- 
 ing southwards is one of the most remarkable features in the 
 configuration of the land. The angular point is also generally 
 succeeded or surrounded by one, or several islands; and where 
 such islands are not apparent, the tendency towards their forma- 
 tion is discoverable by the soundings, which prove the existence 
 of shoals in the places where such islands would otherwise be 
 apparent. A general view of the map of the world will strikingly 
 illustrate these observations. 
 
 105. The South American Peninsula is an example of such 
 a form upon a grand scale. Like all the other forms of this class, 
 it is a triangle, having its base presented towards the north, and 
 its vertex jutting into the Southern Ocean, where it terminates in 
 the point called Cape Horn. 
 
 Its apex is broken by the ocean into a multitude of islands, 
 the largest of which, separated from the main-land by the Straits 
 of Magellan, is called the Tierra del Fuego, or land of fire, from 
 several volcanic peaks which rise from it to the altitude of 4000 
 feet. The southernmost island of the Fuegian archipelago termi- 
 nates in the headland, or promontory, so well known as Cape 
 Horn. 
 
 106. The North American Peninsula has a like form, its 
 southern point being Mexico ; but instead of terminating in the 
 ocean, it is united with the South American peninsula by a tract 
 of land called Central America, which, taken as a whole, may 
 be regarded as an isthmus, although geographers have, in this 
 case, limited that name to its southernmost and narrowest part, 
 called the Isthmus of Panama. 
 
 107. The West Indian Archipelago stands in the same rela- 
 tion to the North American peninsula as the Fuegian archipelago 
 to the southern peninsula. This group of islands, celebrated as 
 being the theatre of the great discovery of Columbus, is included 
 
 154 
 
OUTLINES OF THE LAND. 
 
 m the tract of water enclosed between the northern coast of 
 South, and the southern coast of North, America. When 
 Columbus undertook his voyage, his purpose was to sail to India 
 round the western hemisphere of the globe, and when he arrived 
 at the island of St. Salvador, one of the Bahama group, he ima- 
 gined that he was on the coast of India ; and hence this, and the 
 other islands of the archipelago subsequently discovered, came to 
 be called the West Indies : they are, however, more commonly/ 
 denominated by French and foreign geographers the Antilles. / 
 The extensive tract of sea enclosed by the coasts of North 
 and South America, and the chain of "West Indian Islands, is de- 
 nominated the Gulf of Mexico, and the Caribbean Sea ; the former 
 being included by the southern coast of North America, and the 
 northern of Central America, and the latter by the northern coast 
 of South America, the West Indian Islands, and the eastern 
 coast of Central America. 
 
 108. The Peninsula of Florida presents another example of 
 the like form. It is the southernmost point of North America, 
 jutting into the ocean between the Atlantic and the Gulf of 
 Mexico, and terminating in Cape Sable, directly north of the weU- 
 known harbour and city called Havannah, in the island of Cuba. 
 
 109. Lower California has the same peninsular form, directed 
 southwards. It lies on the western coast of Mexico, from which 
 it is separated by an inlet of the Pacific, called the Gulf of 
 California. It is terminated at its southern point in a headland 
 called Cape St. Lucas. 
 
 110. Greenland, in the extreme north, presents an example of 
 similar formation, being formed into an acute angle, jutting out 
 into the Atlantic towards the south. 
 
 111. Africa, in the Old World, is a stupendous example of the 
 same peninsular outline. Like South America it is triangular, the 
 base being presented to the north, and the vertex to the south. 
 There are no islands below its vertex, but the tendency to the 
 formation of one is indicated by the shoal called the Lagullas 
 Bank, well known to mariners. 
 
 112. Australia has a similar form, terminating with the island 
 now called Tasmania, and formerly known as Yan Diemen's 
 Land. 
 
 113. KTew Zealand, on a much smaller scale, presents a like 
 example, terminating with an island called New Leinster. 
 
 114. It is very remarkable that this tendency to the peninsular 
 form with a southern vertex, not only prevails in the continents^ 
 but is discoverable equally in the more minute outlines of the 
 land which determines the shores of gulfs, bays, and inland seas. 
 
 115. The Spanists Peninsula, including Portugal, is an ex- 
 
 155 
 
THE SURFACE OF THE EARTH. 
 
 ample of the same prevailing form, its southern apex heing 
 marked by the celebrated rock of Gibraltar, separated from the 
 northern coast of Africa by the narrow neck of water called the 
 Strait of Gibraltar. 
 
 116. The Italian Peninsula juts southwards into the Medi- 
 terranean, with the islands of Sicily and Malta, and the small 
 archipelago formed by the Lipari Islands, at its southernmost 
 point, 
 
 117. The Hellenic Peninsula is a like example, terminated 
 by the Morea, and surrounded near its southernmost point by the 
 Ionian Islands. 
 
 118. The Crimea, in the Black Sea, is a peninsula of like form 
 and position, terminating with a southern vertex near Sebastopol. 
 
 119. The Scandinavian Peninsula consists of Norway and 
 Sweden, and enclosed between the Northern Atlantic on the west, 
 and the Baltic and the Gulf of Bothnia on the east, presents, like 
 the others, an apex to the south, and Zealand, and other smaller 
 islands, lie off its southern point. 
 
 120. European Peninsula. — Humboldt observes that Europe 
 itself may be regarded as a great peninsula projecting from Asia, 
 and enclosed between the Mediterranean and Black Sea on one 
 side, and the Baltic and Arctic Ocean on the other. 
 
 121. The Indian Peninsula juts into the ocean southwards, 
 having, like the others, a triangular form, and the island Ceylon 
 off its southern apex. 
 
 122. Further India. — The tract of land called Further India, 
 lying to the south of China, and including Cochin China, Siam, 
 and Burmah, is another example of lilce form, terminating in the 
 Malayan promontory with Singapore at its apex, and the Indian 
 archipelago around its point. 
 
 123. Hemisphere of most Land. — There is a certain hemi- 
 sphere of the globe within which nearly the whole of the land is 
 included, the middle point of which is at the south coast of England. 
 If an observer were elevated directly above this point, so as to 
 obtain a bird's-eye view of the earth, he would see the whole of 
 Europe, Asia and Africa, North America, andthechief part of South 
 America, aU comprised within the visible hemisphere : the only 
 parts of the land which would be included within the hemisphere 
 beyond his view would be the southern point of South America, 
 Australia, and the islands of the Indian Archipelago. 
 
 In Map 8, we have given these two hemispheres, having repro- 
 duced them from the Physical School Atlas of Alexander Keith 
 Johnston, a work which we strongly recommend to students to aid 
 them in comprehending this tract. 
 
 156 
 
EIYEES. 
 
 EIVERS. 
 
 124. Pormatioii of Rivers. — The origin of all rivers is 
 tlie evaporation of the ocean. The surface of the oceans and 
 seas has an extent, as has been already explained, equal ta 
 nearly three-fourths of the whole surface of the glohe. This 
 extensive mass of water is subject to an incessant process of 
 evaporation. In this process, the pure water is separated from the 
 salt and other solid matter which it holds in solution. The vapour, 
 therefore, which ascends into and mixes with the atmosphere, is 
 that of pure fresh water. Being lighter bulk for bulk than the air, 
 it rises into the higher regions, where it is transported in different 
 directions by atmospheric currents. By the operation of tempera- 
 ture and electricity, it is converted into clouds, which, attracted 
 towards the most elevated points of the land, collect in dense 
 masses around the ridges and summits of the mountains, where, 
 being condensed and reconverted into water, and sometimes con- 
 gealed, it is precipitated in the form of rain or snow. From these 
 heights it descends by the common principle of gravitation, either 
 along the surface of the declivities, or through the fissures and 
 interstices of the soil, finding its way to the lower levels ; and, fol- 
 lowing these in their devious and winding course, it at length 
 returns to the sea, with which it mingles, to be again evapo- 
 rated and sent once more through the same series of physical 
 changes. 
 
 125. Effect of a single ridge.— When a tract of country, 
 bounded on either side by the sea, is traversed by an elevated 
 ridge or chain of mountains, the rain and snow deposited upon 
 them descends in streams along their slopes at either side, forming 
 at first rivulets, which, coalescing, swell into larger streams, and 
 acquire the character of rivers. These, following the declivities 
 and winding through the valleys, find their way on the one sidfr 
 or the other to the sea. In this case, the general direction of the 
 rivers will be at right angles to the ridge which traverses the coun- 
 try. The rapidity of their streams wiU be proportionate to the 
 steepness of the declivity, and their length to the distances of 
 the prevailing ridge from one or other coast. 
 
 126. Example, in the Eastern Continent- — An example 
 of the play of this principle is presented in the great eastern 
 continent, where, as has already been explained, the moun- 
 tain-chains running from west to east are much nearer to the 
 southern than to the northern coast. The rivers, therefore, which 
 flow towards the south, are generally shorter and more rapid, 
 while those which flow towards the north, passing over exten- 
 
 157 
 
THE SURFACE OF THE EARTH. 
 
 sive tablelands and plains having little declivity, are compara 
 tively long and sluggish. 
 
 127. Example in South America. — South America pre- 
 sents a similar example. The chain of the Andes traversing the 
 country north and south, and much nearer to the western than 
 the eastern coast, gives a similar character to the rivers, those 
 which flow to the west being short and rapid, and those which 
 flow to the east being longer and slower. 
 
 In the northern part of South America, the principal moun- 
 tain chain, diverging into several distinct ridges of the Cordilleras, 
 produces a complicated system of ravines and valleys, which divert 
 the course of the waters in various directions, so that many of 
 the rivers flow northwards and north-westwards into the Carib- 
 bean Sea. 
 
 128. Effect of Parallel ridges. — When a tract of coun- 
 try is traversed by two ridges in nearly parallel directions, their 
 declivities, which look towards each other, form a valley of greater 
 or less width. The rain precipitated upon these slopes, collecting 
 in streams, descends from either side to the lowest point of the 
 valley where they coalesce, and settling into a bed or channel, 
 flow along the lowest level of the valley, forming a river whose 
 course is parallel to the general direction of the bounding ridges, 
 and which continues its course until it discharges its waters into 
 the sea. 
 
 In ascending a river, it is found, as may be expected, that the 
 quantity of water which flows in it becomes less and less as the 
 distance from its mouth increases. Since the total collection of 
 water must be proportionate to the number and magnitude of the 
 tributaries above the point of observation, the higher that point 
 is, the less will the number of such tributaries be, and consequently 
 the less the quantity of water in the main stream. 
 
 129. (fhief tributaries considerable rivers.— In the case 
 of all the great rivers, the principal tributaries themselves are 
 rivers of considerable magnitude and importance, and some 
 which have been classed as tributaries might with greater pro- 
 priety have been considered as the main stream. 
 
 130. Example of IVEissouri.— Thus for example the Mississippi 
 receives as tributaries, streams so important as the Red River, the 
 Arkansas, the Ohio, the Missouri, and the Illinois. Now the 
 Missouri is itself a river of much greater length, width, and 
 depth than that which above their confluence has been denomi- 
 nated the Upper Mississippi, and if, of two confluent streams, the 
 greater be entitled to be regarded as the continuation of the 
 main stream, the river which is now called the Missouri ought to 
 be denominated the Upper Mississippi. 
 
 158 
 
MISSOUEI AND MISSISSIPPI. 
 
 131. It must not be inferred from what has been liere stated 
 ibat the valley of every river is formed by slopes, baving 
 declivities obvious to tbe eye, or limited by chains of mountains 
 of conspicuous elevation. Most commonly it is quite otherwise, 
 the declivities of the valley being so gentle as to be almost 
 imperceptible, and the summits of the ridges, which limit it, 
 having no elevation which entitles them to the name of mountains. 
 
 132. Portage. — Where the navigation of a river is impeded by 
 Waterfalls, rapids, shallows or other natural obstructions, the 
 space over which goods, and sometimes canoes or boats have to be 
 carried, to meet the navigable part of the stream again, is called 
 a portage. 
 
 133. Examples of rivers of Slorth America, — This division 
 of the western continent being traversed by two ridges, the Eocky 
 Mountains and the AUeghanies, whose general directions are nearly 
 parallel, is divided into three zones, running north and south, the 
 centre and broadest of which is included between the two ridges, 
 the eastern zone sloping down from the AUeghanies to the Atlantic, 
 and the western from the Eocky Mountains to the Pacific. 
 
 134. Eastern rivers. — The disposition of the general relief 
 of the continent, shown by a section of it, running east and west, 
 determines three different directions for the rivers. Those which 
 are formed of the drainage of the eastern slopes of the AUeghanies, 
 flow eastward into the Atlantic, and the distance of the ridge of 
 the AUeghanies from the Atlantic coast not being great, and the 
 surface of the intervening zone being nearly plane, the lengths of 
 the rivers are inconsiderable, and their streams not rapid. 
 
 135. Western rivers. — In the same manner the drainage of 
 the western slope of the Eocky Mountains forms a series of rivers 
 vvhich flowing westward faU into the Pacific. 
 
 136. The Mississippi and its tributaries.— The great ex- 
 tent of the valley included between the ridges of the AUeghanies 
 and the Eocky Mountains, and its great capacity for cultivation, 
 confer upon it an importance which is immensely augmented by 
 the great length through which the rivers which traverse it, are 
 navigable. 
 
 137. The drainage of the western slopes of the AUeghanies, and 
 that of the eastern slopes of the Eocky Mountains, form two 
 systems of rivers, the one flowing from west to east, and the other 
 from east to west, and meeting in a common bed in the centre of 
 the valley. They thus form a main stream traversing the valley 
 from north to south, the magnitude of which increases as it 
 descends southwards, in proportion to the number and magnitude 
 of the streams which flow into it from the one side or the other. 
 This central stream is the Mississippi, which gives its name 
 
 159 
 
THE SUHFACE OF THE EARTH. 
 
 to the entire valley, extending from the GruK of Mexico, into 
 which its waters fall, to the great northern lakes, 
 
 138. Red River — Arkansas— Ohio. — New Orleans, which is 
 the port of the Mississippi, is built at the confluence of the arms of 
 its Delta, about one hundred miles above its mouth. Ascending the 
 river from this point, we encounter successively its vast tributaries, 
 the first of which is called the Red Eiver, which flows into it from 
 the slope of the Rocky Mountains upon its right bank. Proceeding 
 upwards, the next is the Arkansas, on the same side, which itself 
 receives at various points of its course subordinate affluents, among 
 which the principal are the Canadian, the Red Fork, the Salt 
 Fork, &c. A little higher, we come to the Ohio, flowing from 
 the east, after having traversed a vast extent of the great valley, 
 and receiving several large tributaries, such as the Cumberland, 
 the Tennessee, the Wabash, &c. The Ohio carries the chief part of 
 the commerce of the states of Tennessee, Kentucky, Virginia, 
 Ohio, Indiana, Illinois, and the western part of Pennsylvania. It 
 washes Pittsburgh, Cincinnati, and Louisville, while its tribu- 
 taries reach the principal towns of the interior of the adjacent 
 states. It is navigated by steam-boats of the largest class as 
 high as Pittsburgh. 
 
 139. St. Xiouis. — Returning to the confluence of -the Ohio and 
 the Mississippi, and continuing to ascend the latter river, we 
 arrive at St. Louis, a city of the first importance, and likely one 
 day to become the great capital of the valley of the Mississippi 
 and the western division of the States, with New Orleans for its 
 port. Already we see ranged along its quays hundreds of steam- 
 boats of immense tonnage, which ply incessantly between it and 
 New Orleans, carrying down the stream the produce of the 
 interior, and up, innumerable articles of importation. 
 
 140. Illinois.— Immediately above St. Louis we arrive at a 
 point marked by the confluence of three streams, one flowing from 
 the north-east, one from the north, and the other from the 
 north-west, the last being the most considerable. The first is the 
 Illinois river; the second, though less considerable than the third, 
 is taken by geographers as the continuance of the main stream of 
 the Mississippi ; and the third and greatest is the Missouri, regarded 
 as a tributary of Mississippi. 
 
 The Illinois river ascends the state of that name in a north- 
 easterly direction, and is navigable for a considerable distance to 
 a point where it is connected by a canal with Lake Michigan 
 at Chicago. By this means a continuous water- communication is 
 established between New Orleans and the northern lakes, and by 
 those lakes with the St. Lawrence. 
 
 i€0 
 
VIII. — LAND AND WATER. 
 
 THE SURFACE OF THE EAETH, 
 
 OR FIRST NOTIONS OF GEOGRAPHY. 
 CHAPTEE III. 
 
 141. Source of Mississippi. — 142. Missouri and its tributaries. — 143. 
 The Amazons. — 144. Its tributaries. — 145. The Orinoco. — 146, 
 The Rio de la Plata. — 147. The river system of Europe. — 148. 
 General plan of the rivers of the world. Climate. — 149. Deter- 
 mines the animal and vegetable kingdoms. — 150. Its dependence 
 on latitude. — 151. Explained by the varying positions of the 
 earth. — 152. Spring equinox. — 153. Sun vertical at equator. — 
 154. Oblique at all other points. — 155. Its thermal influence in 
 different latitudes. — 156. Position of the earth on 21st June. — 
 157. Days longer than nights in northern hemisphere. — 158. Tem- 
 perature depends on sun's altitude and length of day. — 159. 
 Thermal influence greatest on 21st June in northern hemisphere. 
 — 160. Position of the earth at autumnal equinox. — 161. Why the 
 longest day is not the hottest. — 162. Why the summer is warmer 
 than the spring. — 163. The Dog-days. — 164. Like phenomena in the 
 southern hemisphere. — 165. Position of the earth on 21st December. 
 — 166. Winter season explained. — 167. Why the shortest day is not 
 the coldest. — 168. The Tropics. — 169. The sun can only be vertical 
 within them. — 170. Illustration of the varying position of the earth 
 in the successive months. — 171. The ai-ctic polar circles and the 
 frigid zones. — 172. Diurnal and nocturnal phenomena which cha- 
 racterise them. — 173. The torrid zone. — 174. Sim vertical twice a 
 year in the torrid zone. — 175. Temperate zone. 
 
 Lakdker's Museum of Science. m 161 
 
 No. 115. 
 
THE SUEFACE OP THE EARTH. 
 
 141. Source of Mississippi.— Ascending the main stream from 
 its point of confluence with, the Missouri, after passing several 
 tributaries of less importance, we arrive at the falls of St. Anthony, 
 which constitute the limit of its navigable course. Above these 
 we find its source in a sheet of water, called Lake Istaca, situate 
 near the northern limit of the territory of the United States, 
 and at a short distance west of Lake Superior. 
 
 142. Missouri and its tributaries — Returning to the con- 
 fluence of the Mississippi with the Missouri, and ascending the 
 latter stream, we find innumerable tributaries, variously denomi- 
 nated Smoky-hill-fork, Republican-fork, Piatt -river. White- 
 river, YeUow-stone-river, &c., until the stream, reduced to a 
 number of diverging threads, loses itself in the flanks of the 
 Rocky Mountains. 
 
 Such is a brief and rapid view of this prodigious vein of inland 
 navigation. As shown in our general plan of the rivers, the total 
 length of the Mississippi and its chief tributary is estimated at 
 4500 miles. 
 
 143. The Amazons. — Among the rivers of Southern America, 
 which flow from the western declivities of the chain of the Andes, 
 by far the most important is the Amazons, which, considered 
 merely in its geographical character, ranks as the greatest of 
 rivers. The total length from the mouth to the source of any one 
 of its thousand tributaries, is less than the length of the 
 Mississippi similarly measured, but numerous and large as the 
 tributaries of the latter are, those of the Amazons are still 
 greater in number, width, and depth. 
 
 This immense stream, and its countless affluents, drain a 
 vast plain lying between the tableland of Brazil, on the south, 
 and the chain of mountains rising from a similar tableland of 
 less extent, on the north, called the tableland of Paramo. It 
 receives tributaries accordingly from an extensive series of 
 declivities completely surrounding it, from those of Brazil on the 
 south, from, the Andes of Peru on the south-west, from the Andes 
 of duito on the north-west, and from those of the mountain- 
 chains of Paramo on the north. 
 
 The plain and surrounding declivities drained by this immense 
 river system, is little less in extent than 3,000000 of square 
 miles, being ten times the magnitude of the French empire. Its 
 largest branch, considered as the commencement of the main 
 stream, is called the Maranon, a name which is sometimes applied 
 to the entire river. The main river and its tributaries are 
 navigable at distances of nearly 2500 miles from its mouth, and 
 its width, near its mouth, being nearly 100 miles, it resembles an 
 arm of the sea more than a river. 
 162 
 
AMAZONS — ORINOCO — PLATA. 
 
 144. The tributaries of this river are severally so considerable 
 in magnitude and importance, that geographers are not agreed 
 :as to which of them should be regarded as the main stream, and , 
 the name Amazon is generally confined to the part of the river 
 below the confluence of several chief tributaries, which unite 
 nearly at the point where the Eio Negro or Black Eiver joins the 
 Amazons. A view of a good map of this part of Southern/ 
 America, will give the reader a more clear idea of the course of 
 this river and its tributaries, than could any mere verbal descrip- 
 tion. The greater tributaries are above twenty in number, 
 aW. of which are navigable to a point near their sources, while 
 the lesser ones are countless. 
 
 Notwithstanding the geographical superiority of the Amazons, 
 and its vast extent of navigable water, it is inferior in commercial 
 importance to the Mississippi ; the districts of country traversed 
 by the river and its branches consisting of tracts of natural 
 forest, and uncleared and uninhabited ground. 
 
 145. The Orinoco, another of the great rivers of the 
 ■southern division of the new continent, drains a valley in- 
 cluded between the tableland of Paramo, the eastern chain of 
 the Cordilleras, and the plateau of Caraccas. This river, 
 having its source near that of the Negro, flows first north, 
 and then east, discharging its waters into the Atlantic, through 
 a delta, at the borders of the Caribbean sea, opposite the island 
 ■of Trinidad. 
 
 146. The Rio de la Plata.— The third great river of South 
 America is that which near its source is called the Parana, and 
 near its mouth the Plata. It discharges its waters into the South 
 Atlantic, at Buenos Ayres, after having flowed down a valley 
 included between the Andes of Chili and the Brazilian mountains. 
 The length of this river is estimated at 2700 miles, and for 200 
 miles above its mouth it is nowhere less' than 170 miles wide. 
 
 147. The River System of Europe is as inferior to that of 
 the new continent in geographical, as it is superior to it in com- 
 mercial and social importance. "With the exception of some of 
 the lines of river-communication in the United States, the world 
 can afibrd no parallel for the spectacle of commercial and 
 social movement presented by the European rivers. The gentle 
 declivities of the water-sheds from which they derive their 
 sources, and the general flatness of the plains over which they 
 flow, are eminently favourable to their commercial utility. 
 
 In the western division of Europe, the chain of the Alps and the 
 German mountains form the ridge, along the slopes of which, 
 north and south, the waters flow towards the Atlantic on the one 
 side, and the Mediterranean and Black Sea on the other. 'In the 
 M 2 163 
 
Eivers of tlio Eastern Hemisphere. 
 
 Rivers of the "Western Hemisphere. 
 
CLIMATE. 
 
 eastern division there is no mountain-chain thus to divide tho 
 drainage. A slight and imperceptible elevation of the general 
 plain produces two opposite water-sheds, commencing in a low 
 range of hills separating the sources of the Dnieper from those 
 of the Yistula, and winding along the plain to the tableland of 
 Valdai, which forms its summit, 1200 feet above the level of the 
 sea. The ridge then turns northward towards Lake Onega, and, 
 following a winding course, terminates in the Ural Mountains, 
 about 62° N. lat. 
 
 The drainage of the north side of this ridge forms the rivers 
 which How into the Baltic and the White Sea, that of its southern 
 declivity those which flow into the Black Sea and the Caspian. 
 
 148. General Plan of the Rivers of the World. — The prin- 
 cipal rivers of the world, with their tributaries, their embouchures, 
 and their sources, are exhibited in one general plan on the oppo- 
 site page, where their lengths are indicated. 
 
 CLIMATE. 
 
 149. Since the prevailing character of the animal and vegetable 
 kingdoms, in each division of the earth's surface, depends chiefly 
 on climate, it is necessary, on that account alone, independent of 
 many other considerations, that the student in geography should 
 be rendered familiar with the conditions, which in each part of 
 the globe determine the varying vicissitudes and temperature of 
 the seasons. 
 
 150. Dependence of Climate on Z.atitude. — The first and 
 chief condition which determines the climate of a country, is its 
 position with respect to the equator. It may be stated, subject 
 to some special qualifications, that the nearer any country is to 
 the Line, or what is the same, the lower its latitude, the higher 
 will be the mean temperature of its seasons. 
 
 The reason pf this is partly geographical and partly astro- 
 nomical. 
 
 The earth revolves diurnally upon an axis, so directed that 
 the equatorial parts are presented either exactly or nearly to 
 the sun. They are presented exactly to that luminary at the 
 epochs of the equinoxes, m March and September. From March 
 to June they are gradually more inclined from the sun towards 
 the south, the northern hemisphere inclining towards that 
 luminary, so as to receive its rays more directly, and in greater 
 quantity than the southern hemisphere. This inclination of 
 the globe increases constantly from March to June, and then 
 decreases from June to September. The northern hemisphere 
 is thus more and more exposed to the light and warmth of the 
 
 165 
 
THE SURFACE OF THE EARTH. 
 
 mm, from March to June ; tlie days during that interval are- 
 gradually longer and •warmer. It is constantly less inclined 
 from June to September; the days during that interval are 
 gradually shorter and less warm. 
 
 Hence it is, that in the northern hemisphere the longest day» 
 and highest temperature take place after June, the temperature 
 after March being more moderate. The interval between March 
 and June constitutes, therefore, the spring, and the interval 
 between June and September, when the accumulated effects 
 of heat are greater, the summer. 
 
 151. This varying position of the earth towards the sun will be 
 rendered more easily intelligible by illustrative diagrams. 
 
 Let N s in these four figures represent the axis of the earth, 
 N being the north, and s the south pole. Let e o, at right angles 
 to N s be the equator, and let s' be the direction of the sun. 
 
 152. In fig. 8 is shown the position of the earth on the 21st of 
 March, the day of the spring equinox. The equator E is then 
 presented exactly in the direction of the sun, the light and heat 
 of which are equally distributed between the two hemispheres. 
 
 Fig. 8. Fig'. 9. 
 
 s' 
 
 21st September. 21st December. 
 
 The boundary of the enlightened hemisphere passes through the 
 poles N and s, and divides into two equal parts all the parallels- 
 of latitude. As the earth revolves, therefore, upon its axis, each 
 place upon its surface is during equal intervals exposed to and. 
 •withdrawn from the sun's light. In other words, the days and^ 
 nights are equal in all parts of the earth. 
 166 
 
CLIMATE. 
 
 153. As the earth turns upon its axis N s, all the places upon 
 the equator e q are brought successively to the point e, directly 
 under the sun. In other words, at all such places the sun is 
 vertical daily at noon. 
 
 154. At all other parts of the earth between e and lir, or 
 between e and s, the sun is seen at noon obliquely, or what is the 
 same, it is at a distance greater or less from the zenith. And 
 the more distant the place is from the equator, the more distant 
 will the sun be from the zenith at noon. 
 
 155. But since the thermal influence of the sun depends in a 
 great degree upon its proximity to the zenith at noon, it follows 
 that this influence will gradually decrease in going from e to ]sr, 
 or from e to s. The temperature, therefore, of the climate at the 
 time of the equinox will gradually diminish as the latitude 
 increases. 
 
 But since any two places at equal distances from the equator, 
 north and south, would be presented towards the sun at noon with 
 equal obliquities, it follows that so far as depends on this circum- 
 stance, the thermal influence of the sun at places having equal 
 latitudes north and south, will be the same at the time of the 
 equinoxes. 
 
 156. The position of the earth with relation to the sun on the 
 21st of June is shown in fig. 9. The equator e in the interval 
 between the 21st of March and the 21st of June, has gradually 
 declined to the south. The north pole ]sr has consequently been 
 turned more and more towards the sun s', and the south pole s has 
 been turned more and more from it. In this position, therefore, it 
 is evident that the sun shines more fully on the northern, and less 
 so on the^ southern hemisphere. The point t, to which it is 
 vertical at noon, is now, not as in the former case upon the 
 equator, but at the distance of 23^° north of it. Places in the 
 northern hemisphere above this point are shone upon by the sun 
 at noon with much less obliquity than places having equal lati- 
 tudes in the southern hemisphere. 
 
 157. The circle which bounds the hemisphere of the earth 
 enlightened by the sun, divides all the parallels of latitude 
 unequally, the larger part of those in the northern hemisphere 
 being enlightened, and the larger part of those in the southern 
 hemisphere being dark. 
 
 It follows, therefore, that at this time the days are longer than 
 the nights in the northern, and the nights longer than the days in 
 the southern hemisphere. 
 
 158. Now the temperature of the seasons, in any given place, 
 depends conjointly on the altitude to which the sun rises, and on 
 the length of the day ; for the greater the altitude is, the more 
 
 167 
 
THE SURFACE OP THE EARTH. 
 
 directly will the solar rays fall upon tlie place ; and the longer 
 the day is, the longer will he the interval during which the 
 thermal influence of the sun is exerted, and the shorter will be 
 the interval during which its presence will be withdrawn. 
 
 159. For all these reasons, therefore, on the 21st of June, when 
 the northern hemisphere is most inclined towards the sun, and 
 the southern most inclined from it, the thermal influence of the sun 
 will be greater in the northern, and less in the southern hemi- 
 sphere, than at any time from the 21st of March to the 21st of June. 
 
 During this interval the northern hemisphere is gradually 
 more and more inclined towards the sun, and therefore the length 
 of the day is continually increasing, as well as the altitude to 
 which the sun rises at noon. These two circumstances combine 
 in gradually increasing the thermal influence of the sun from the 
 21st of March to the 21st of June. 
 
 The same circumstances will show that during the same interval, 
 the thermal influence of the sun in the southern hemisphere is 
 gradually diminished ; the days being there constantly shorter, 
 and the altitude to which the sun rises at noon constantly less. 
 
 After the 21st of June the northern hemisphere is gradually less 
 and less inclined towards the sun, and the southern less and less 
 inclined from it, until at length on the 21st of September, the day 
 of the autumnal equinox, the earth resumes the position, fig. 10, 
 with relation to the sun which it had on the 21st of March, the 
 equator e being then, as before, directed exactly towards the sun. 
 
 160. The two hemispheres therefore, as in March, being equally 
 exposed to the sun, receive from it the same thermal influence, 
 and the parallels of latitude being all bisected by the circle 
 which bounds the enlightened hemisphere, the days and nights 
 are equal at all parts of the earth. 
 
 Since the altitude to which the sun rises, and the length of the 
 days at equal intervals before and after the 21st of June, are 
 the same, and therefore the thermal influence of the sun also the 
 same, it might be inferred that the temperature of the weather 
 would likewise be the same ; and if this inference were just, it 
 would follow that the season from the 21st of March to the 21st of 
 June, would be similar in all its thermal characters to the season 
 from the 21st of June to the 21st of September, except that the 
 succession of temperatures would be developed in a contrary 
 order. Thus it would be expected that the temperature of the 
 weather ten or twenty days after the 21st of June would be 
 identical with its temperature ten or twenty days before the 21st 
 of June. 
 
 161. But it is notorious that the thermal phenomena are not at 
 all in a ccordance with this ; the season from the 21st of March to the 
 
 1G8 
 
CLIMATE. 
 
 21st of June, called the Spring, liaving generally a much lower 
 temperature than the season from the 21st of June to the 21st of 
 September, called the Summer. 
 
 Let us see, then, whether we cannot render evident the cause 
 of this. 
 
 The temperature of the weather in a given place, depends not 
 exclusively upon the thermal influence exercised by the sun 
 during each day. It must be remembered that when the days are ^ 
 much longer than the nights, and the sun rises to a considerable 
 altitude, a greater quantity of heat is imparted to the atmosphere 
 and to all objects upon the surface during the day, than is lost 
 during the night, and, consequently, an increment of heat is 
 given to all such objects every twenty-four hours. The Conse- 
 quence is, that the general effect of the sun's thermal influence 
 during each successive twenty-four hours is to augment the 
 temperature, and thus to increase by accumulation the heat from 
 day to day ; and this daily increase will obviously continue until, 
 by the shortening of the days and the decrease of the sun's 
 altitude, the increment of heat during the day becomes equal to 
 its decrement during the night. The day on which that takes 
 place will be the hottest day, because it will be that upon which 
 the daily accumulation will cease. After this, the days being 
 further shortened, and the sun's altitude further diminished, the 
 increment of heat during the day wiU be less than its decrement 
 during the night, and after each interval of twenty-four hours 
 there will be on the whole a decrease of heat, and so the tempe- 
 rature of the weather will be diminished. 
 
 162. Now, from a due consideration of these circumstances, it 
 will be easy to see why the season of summer is warmer than the 
 season of spring, although the sun's altitude and the length of 
 the days are, on the whole, precisely the same both in one season 
 and the other, only succeeding each other in a contrary order. 
 Until the 21st of June the daily thermal influence of the sun con- 
 tinually increases, for the reasons just explained, and it is greater 
 on the 21st of June than on any other day before or after. But 
 although this thermal influence decreases after the 21st of June it is 
 still considerable, and from day to day adds something more or less 
 to the heat already accumulated in the atmosphere, and conse- 
 quently continues to augment the temperature ; and this increase 
 only ceases, when the thermal action of the sun during the day, 
 begins to be counteracted and balanced by the loss of heat during 
 the night. 
 
 163. Hence it arises that a certain interval, from the 21st of 
 June to the latter part of July, is generally the hottest part of 
 the summer, being called the Dog-day either because of the 
 
 169 
 
THE SURFACE OP THE EARTH. 
 
 prevalence of canine madness during that period, or because at an 
 early epoch in astronomical history the Dog-star rose before the 
 sun in the morning at that season, and thus harbingered the God 
 of Day. It may even have happened that the Dog-star took its 
 name originally, from the prevalence of canine madness at that 
 season. 
 
 164. The circumstances which explain the phenomena of summer 
 in the northern hemisphere, will also explain those of winter during 
 the same interval in the southern hemisphere, since the southern 
 hemisphere at all times is inclined from the sun, exactly as much 
 as the northern hemisphere is inclined towards it, as will be 
 apparent by reference to fig. 9. 
 
 165. After the 21st of September (fig. 10), the day of the 
 autumnal equinox, the equator is gradually inclined towards the 
 north, and the northern hemisphere gradually inclined from the 
 sun, and this inclination constantly increases until the 21st 
 of December, when it is greatest, as shown in fig. 11. 
 
 The solar rays, as will be apparent from the figure, then fall 
 with greatest obliquity on the northern hemisphere, and with 
 least obliquity on the southern. The parallels of latitude are un- 
 equally divided, in both hemispheres, by the circle which bounds 
 the enlightened part of the earth. In the northern hemisphere 
 the greater portions of these parallels are dark, and the lesser 
 portions enlightened, while the contrary takes place in the southern 
 hemisphere. The days are, therefore, shorter than the nights in 
 the northern, and longer in the southern hemisphere ; and the 
 sun rises only to low altitudes in the former, but to considerable 
 altitudes in the latter. In fine, all the circumstances show that, 
 in this position of the earth, the summer commences in the 
 southern, and the winter in the northern hemisphere. 
 
 166. After the 21st of December, the inclination of the northern 
 hemisphere from the sun gradually and constantly diminishes 
 until the 21st of March, when the equator is once more presented 
 directly to the sun, which aff'ects both hemispheres alike. 
 
 Since the 21st of December is the shortest day, and that upon 
 which the sun rises to the least altitude, it is consequently that on 
 which its thermal influence is least, and it might therefore be 
 expected to be the coldest day, and consequently to be mid- 
 winter. It is notorious, on the contrary, that the coldest weather 
 is at a later period. This is explained upon the same principles 
 exactly, as those which show why the 21st of June is not the 
 hottest day. 
 
 167. The decrement of heat which takes place in the atmosphere 
 owing to the length of the night, the shortness of the day, and 
 the low altitude of the sun on the 21st of December, is greater 
 
 170 
 
CLIMATE. 
 
 than the decrement on any succeeding day ; but still on these 
 succeeding days there is still a decrement of heat, though a less 
 one, and therefore on the whole the temperature must continue to 
 fall, and it will so continue until by the increasing length of the 
 day, and the decreasing length of the night, and the increasing 
 altitude of the sun, the increment of heat during the day becomes 
 equal to its decrement during the night ; after that takes place, the , 
 result of the sun's influence during each twenty-four hours willb/ 
 on the whole an increase of heat, and the temperature of the 
 weather will accordingly be augmented. 
 
 Hence it is that the winter season in the northern hemisphere is 
 the_interval between the 21st of December and the spring equinox; 
 the same interval being the summer season in the southern 
 hemisphere. 
 
 The altitude to which the sun rises at noon constantly increases 
 until the 21st of June, when it becomes as it were stationary, 
 and afterwards decreases. In the same manner the altitude at 
 noon constantly decreases until the 21st of December, after which 
 it increases, having remained in like manner stationary for a 
 certain interval. These two epochs have therefore been called 
 the solstices, one being denominated the summer, and the other 
 the winter solstice, from a Latinwordwhichsignifi.es the standing 
 or stationary position of the sun, 
 
 168. When the northern hemisphere is most inclined towards 
 the sun, as sKown in fig. 9, the sun is vertical at noon to all 
 places at 23|° north of the equator. Before that day, and after 
 it, the sun's altitude at noon is less than 90°, and consequently it 
 does not reach the zenith. It may be considered therefore 
 gradually to approach the zenith at such places until the 21st of 
 June, and then gradually to recede from it. 
 
 From this circumstance the parallel of latitude which passes 
 through such places has been called the tropic. 
 
 Similar phenomena are produced at the corresponding parallel 
 of south latitude, and these parallels are accordingly called 
 respectively, the northern and southern tropic, or the Tropic of 
 Cancer and the Tropic of Capricorn. 
 
 169. It will be evident, by considering the diagrams, fig. 9 and 
 fig. 11, that the sun can never be vertical at noon to any part of 
 the earth except to places which lie between the tropics, and at 
 all such places it is vertical at noon twice in the year. 
 
 170. These astronomical causes of the vicissitudes of the seasons 
 may be further illustrated by the diagram, fig. 12, .which pre- 
 sents a perspective view of the earth in twelve successive positions 
 which it assumes in one revolution round the sun, the observer 
 being supposed to view it from the north side of the plane of its 
 
 171 
 
THE SUEFACE OP THE EARTH. 
 
 orbit. Its motion in that case is in a direction contrary to that 
 of the hands of a clock, or to that of a common screw when turned 
 so as to cause it to move inwards or forwards. 
 
 While the globe thus moves round the sun, its axis keeps con- 
 stantly the same direction, so that in any one position it is 
 
 Fig. 12. 
 21st Sept. 
 
 parallel to the direction which it had in any other position. On 
 the 21st of June, as shown to the right of the diagram, the 
 northern extremity of the axis, or the north pole, leans towards 
 the sun through an angle of 23^". If we suppose a parallel of 
 latitude to be described at that distance from the pole, all places 
 within that parallel will receive the light of the sun, and the 
 rotation of the globe on its axis will not throw any of these places 
 upon the dark side of the earth. It follows, therefore, that on 
 the 21st of June the sun does not set at all to any place above 
 that parallel, and there is consequently twenty-four hours day. 
 
 By referring to the position of the earth, on the extreme left 
 of the figure, which it has on the 21st of December, it will be seen 
 that then the north pole is inclined from the sun, just as much as 
 it was inclined towards it on the 21st of June, and that the same 
 places, bounded by the parallel of latitude 23|° from the pole, 
 which on the 21st of June lay altogether on the enlightened side 
 of the globe, and enjoyed twenty-four hours day, now lie on 
 the dark side, and have twenty-four hours night. As the sun 
 never sets to such places on the 21st of June, so it never rises 
 to them on the 21st of December. 
 
 In the positions successively assumed by the earth, in J uly and 
 August, til 9 north pole is less and less inclined towards the sun, 
 and the part around it, which has no sunset, is limited by a less 
 and less parallel of latitude. On the 21st of September, the equator 
 being presented to the sun, there is no part around the pole 
 172 
 
SEASONS AND CLIMATE. 
 
 which has continual day, all places being twelve hours exposed 
 to the sun, and twelve hours removed from it. 
 
 After the 21st of September, thie north pole begins to incline 
 from the sun, and in October, a small portion around it is entirely 
 deprived of the sun's light. This portion, thus involved in con- 
 tinual night, constantly increases in extent until the 21st of 
 December, when it extends to the parallel of latitude already 
 mentioned. After the 21st of December, the north pole is less 
 and less inclined from the sun, so that the portion involved in 
 continual night is less in January, and still less in February, 
 and on the 21st of March, as on the 21st of September, there are 
 twelve hours day and twelve hours night to all places. 
 
 After the 21st of March, the north pole begins again to lean 
 towards the sun, and a portion of the earth around it enjoys 
 continual day, this portion incrsasing in extent during the 
 months of April and May, and attaining its greatest magnitude 
 on the 21st of June, when, its extent, as already explained, is 
 a circle 23^° from the pole. 
 
 171. The parallel which is 231" trom the pole, is 661° from 
 the equator, and consequently has the latitude north of 66J°. 
 
 This parallel of latitude is called the Arctic or Polar Circle, 
 and the polar region included by it is called the Frigid 
 Zone. 
 
 All the circumstances, which are here explained, respecting the 
 north polar region, circumscribed by the arctic circle, will be 
 equally applicable to the corresponding region, circumscribed by 
 a circle 23^° from the south pole. Such a circle is called the 
 South Polar or Antarctic Circle, and the polar region circum- 
 scribed by it is the Southern Frigid Zone. 
 
 172. Although the diurnal and nocturnal phenomena of the two 
 frigid zones, northern and southern, are precisely the same, they 
 are not simultaneous, those which are identical being produced 
 at opposite epochs of the year, as will be rendered evident by 
 examining attentively the several positions of the illuminated and 
 dark hemispheres of the globe in the successive months, in 
 fig. 12. "When the entire north polar circle is enlightened on 
 the 21st of June, the entire south polar circle is dark. There is 
 continual day in the one, and continual night in the other. On 
 the contrary, when the entire north polar circle is dark on the 
 21st of December, the entire south polar circle is enlightened. 
 There is continual night in the one, and continual day in the 
 other. 
 
 The phenomena on the 21st of June, therefore, in the northern 
 frigid zone, are identical with those of the 21st of December in 
 the southern frigid zone, and vice versa, 
 
 17S 
 
THE SURFACE OF THE EARTH. 
 
 In tlie like manner, there is just so mucli of the northern polar 
 region enlightened, and of the southern polar region darkened, in 
 July, as there is of the northern polar region darkened, and the 
 southern enlightened, in January. The diurnal and nocturnal 
 vicissitudes, therefore, of the northern frigid zone in July, are 
 identical with those of the southern frigid zone in January, and 
 vice versa. 
 
 If the reader will take the trouble of following the position of 
 the earth from month to month, as shown in fig. 12, he will be 
 able to satisfy himself, that at all intervals of six months the 
 vicissitudes of light and darkness are in the same way reci- 
 procated between the two frigid zones. 
 
 It might be inferred, that the continual presence of the sun 
 above the horizon, would necessarily produce a great calorific 
 eflfect ; and at least during that portion of the year, during 
 which they are respectively inclined towards the sun, the polar 
 circles would enjoy intense heat. That such, however, is not 
 the case is easily explained. The heat imparted by the sun 
 to any part of the earth exposed to its influence, depends, as 
 already stated, on two conditions : first, the altitude to which 
 it rises, and secondly, its continuance above the horizon, or the 
 length of the day. But the former condition has a vastly 
 greater influence upon the thermal effects than the latter. 
 Although, therefore, the continuance of the sun above the 
 horizon, at the polar circles, is favourable to the development 
 of heat, yet the very low altitude to which it rises counter- 
 acts this effect; so that within the polar circles, even with 
 the influence produced by the continuous presence of the sun, 
 the general temperature is invariably below that at which 
 water freezes. 
 
 It is from this continuance of a temperature so low that the 
 frigid zone has taken its name. 
 
 173. Torrid Zone. — The part of the earth included between 
 the tropical circles, which comprises all places having a latitude 
 less than 23|°, is called the Torrid Zone, 
 
 Although the exposure of these regions to the heat of the sun 
 varies within certain limits between December and June, being most 
 completely presented to that luminary in March and September, 
 they, nevertheless, receive the solar influence in a much more 
 powerful degree, than the parts of the globe having higher lati- 
 tudes in the one hemisphere and the other. 
 
 It is demonstrated in physics, that the heating power of the 
 sun's rays falling upon any object increases in proportion as they 
 approach to the perpendicular direction upon it. At the time of 
 the equinoxes, therefore, the noon-day sun upon the Line, project- 
 174 
 
ZONES. 
 
 ing its rays perpendicularly downwards, produces the greatest 
 possible calorific effect. 
 
 At these times, also, the sun, rising precisely in the east, 
 ascends the heavens at right angles to the horizon, until at noon it 
 reaches the zen*ith ; after which it descends perpendicularly in like 
 manner, and sets precisely in the west. 
 
 174. Sun vertical twice a year in the Torrid Zone. — 
 Every point of the torrid zone is presented, at one period or 
 another of the year, directly to the sun, so that there are two 
 days in the year upon which the sun at noon is vertical at such 
 places, and its extreme departure from the zenith at noon is 
 always very limited. Thus to places on the Line, the sun at noon 
 never departs from the zenith more than 23|°, and even at the 
 limits of the torrid zone, that is, at the latitude 23^° north or 
 south, the sun which on the 21st of June is vertical at noon in 
 the northern, and on the 21st December in the southern hemi- 
 sphere, is not more than 47° from the zenith at noon on the 21st of 
 December in the northern, and on the 21st of June in the southern 
 hemisphere ; for all places within the tropics the extreme distance 
 of the sun from the zenith at noon must always be less than 47**. 
 
 Indeed it may be stated generally, that for places between the 
 tropics, the greatest distance of the sun at noon from the zenith 
 will be found by adding 23 1° to the latitude of the place, and 
 that twice in the year it passes through the zenith at noon. 
 
 When it is considered that the temperature of the weather 
 mainly depends on the distance of the sun from the zenith at noon, 
 increasing as that distance decreases, it will be easily understood 
 why the climate of the torrid zone is characterised by that ex- 
 tremely elevated temperature from which it takes its name ; for 
 although the sun at noon, during a certain part of the year, is at 
 XI distance more or less considerable from the zenith, the interval 
 during which it has this distance is comparatively short, and that 
 during which it is in or near the zenith much more considerable. 
 
 The hottest seasons occur, not as might be first supposed, upon 
 the Line, but at and within a limited niunber of degrees of the 
 tropics; because at such latitudes the sun at midsummer con- 
 tinues to cross the meridian very near to the zenith for a much 
 more considerable time than on the Line at the epochs of the 
 •equinoxes, where its change of declination is much more rapid. 
 
 175. Temperate Zone.— The parts of the globe included 
 between the limits of the torrid and frigid zones, — that is between 
 the latitudes 23|° and 66|°, — is exempt from the extremes of 
 temperature which characterise the one and the other of these 
 regions. Within its limits the sun never ascends to the zenith, 
 nor on the other hand are the phenomena of continuous day cr 
 
 id 
 
THE SUEFACE OF THE EARTH. 
 
 continuous night ever witnessed. The warmth of summer is 
 produced by long days, combined with moderate meridian 
 altitudes, and the rigour of winter is mitigated by the presence of 
 the sun above the horizon for a considerable interval, even on the 
 shortest days. 
 
 It must not be understood, that within the limits of what is 
 thus called the temperate zone, the climates are uniformly the 
 same. On the contrary, in approaching those limits, at which it 
 is united with the torrid and the frigid zones, the character of 
 the climates approach gradually to those peculiar to the one extreme 
 zone and the other, so that the climates of the higher latitudes of 
 the temperate zone diffbrs but little from those of the lower 
 latitudes of the frigid zone, while those of the lower latitudes of 
 the temperate zone, approximate gradually and insensibly to 
 those of the higher latitudes of the torrid zone. In fact, within 
 the limits of the temperate zone are included a much greater 
 variety of climates than any which characterise either of the 
 extreme zones. 
 
VI. — TUBKE Y — GREECE. 
 
 THE SURFACE OE THE EARTH, 
 
 OR FIRST NOTIONS OF GEOGRAPHY. 
 
 CHAPTEE TV. 
 
 176. Climate, dependent on elevation. — 177. Vegetation of tlie Himalayas. 
 — 178. Vegetation of tlie Andes. — 179. Animals of the tropics. — 180. 
 The Himalayas — Animals inhabiting them — 181. The local character 
 of climate. — 182. Heat received from celestial spaces.— 183. Why the 
 temperature of the earth is not indefinitely increased. — 184. Effect 
 of clonds. — 185. Effect of contact of air and earth. — 186. Thermal 
 effects of a luiiform surface. — 187. Why this regularity does not 
 prevail. Moitntains. — 188. Maps and glohes in relief. — 189. John- 
 ston's Physical Maps. — 190. Mountain ranges not uniform. — 191. 
 Spurs. — 192. Relief of the earth's surface. — 198. Effect of the con- 
 templation of mountain scenery. — 194. The Pyrenees. — 195. The 
 Alps. — 196. Average height of continents. — 197. New mountain 
 ranges possible. The Ocean.— 198. Greatest depth. — 199. Uses of 
 the ocean. — 200. General system of evaporation and condensation. — 
 201. Climatic effects.— 202. Ocean currents. — 203. Antarctic drift 
 current. — 204. Its equatorial course. — 205. Gulf stream.— 206. 
 Course and limits of ocean currents evident. — 207. Ocean rich ia 
 animal life. — 20?. Moral impressions. 
 Lakdner's MuaEUM op Science. n 177 
 
 No. 117. 
 
THE SUEFACE OF THE EARTH. 
 
 176. Climate dependent on elevation. Snow Line. — It has 
 
 been explained in our Tract on Terrestrial Heat, that as we 
 ascend into the atmosphere from the level of the sea, the mean 
 temperature gradually decreases, and beyond a certain elevation 
 it falls even below the freezing point of water ; above this limits 
 therefore water cannot exist in the liquid state, and must assume 
 the state of snow or ice. Such an elevation is accordingly 
 designated the limit of perpetual snow, and it is marked on all 
 lofty mountains by the limits of their snow-covered sides. This 
 boundary is accordingly called the Snow Line. 
 
 It may be stated as a general fact, subject nevertheless to 
 some local qualification, that the elevation of the snow-line is. 
 greatest at those parts of the earth, where the climate at the level 
 of the sea is hottest, and that its elevation decreases with the 
 decrease of the mean temperature of the same level. The snow- 
 line, therefore, has the greatest elevation within the tropics, and 
 decreases gradually with the increase of latitude, until at the 
 polar circles it falls to the surface. 
 
 Since climate therefore varies, not only with the latitude but 
 Tvith the elevation of the place above the level of the sea, it 
 foUows that in mountainous regions a variety of climates will 
 prevail, depending on the elevation of the summits. If that 
 elevation exceed the limits of the snow-line, all varieties of 
 climate between that which characterises the sea level, or 
 which is natural to the plateaux on which the mountains stand, 
 and the climate of the poles are found, and consequently a 
 corresponding variety of natural productions, vegetable and 
 animal, and corresponding susceptibilities of culture prevail. 
 This is a circumstance which gives much interest to mountainous- 
 countries, and often confers upon them great commercial and 
 social advantages. 
 
 It is evident, also, that the higher the mean temperature of 
 the plateaux is upon which snow-capped mountain ranges stand, 
 the greater will be the varieties of climates exhibited between 
 their summits and their bases, and the greater consequently will 
 be also the variety of natural productions and artificial culture. 
 Hence arises the magnificent display of vegetation exhibited in 
 those ranges of the Andes and Cordilleras, and other lofty ridges 
 which intersect the torrid zone. 
 
 177. Vegetation of the Himalayas. — Although the chain of 
 the Himalayas far exceeds in elevation the Andes and Cordilleras 
 of South America, they are thus, from their geographical position, 
 being situate far beyond the limits of ttie torrid zone, excluded 
 from the advantages here noticed, and they present none of 
 that inexhaustible variety of phenomena by which the ridges 
 178 
 
HIMALAYAS AND ANDES. 
 
 which rise to such vast altitudes from the plateaux of the 
 torrid zone are characterised. Beautiful as are the yalleys of 
 Kumaoon and Wepaul, they are not signalised hy the presence of a 
 single palm-tree. On the southern slope of the Paropamisan 
 range, which extends over 350 miles of Persia and Afghanistan, 
 and separates the deserts of Yezd and Turkestan, Nature nowhere 
 displays that profusion of arborescent grasses, tree-ferns, heli- 
 conias, and orchidese which are witnessed on the higher plateaux 
 of the tropical mountains. On the slopes of the Himalayas, under 
 the shade of the deodar and the large-leaved oak peculiar to 
 these Indian alps, the rocks of granite and mica-schist are clothed 
 with forms closely resembling those which characterise Europe 
 and northern Asia. The species indeed are not identical, but 
 they are similar in their aspect and physiognomy, including 
 junipers, Alpine birches, gentians, parnassias, and prickly species 
 of ribes. The chain of the Himalayas is also wanting in those 
 imposing volcanic phenomena, which in the Andes and the 
 Indian Archipelago often recall to the inhabitants, in characters 
 of terror, the existence of forces developed within the globe. 
 Moreover, on the southern declivity of the Himalayas, where the 
 vapour-loaded atmosphere of Hindostan deposits its moisture, the 
 region of perpetual snow descends to a zone the elevation of 
 which does not exceed 13000 feet. Thus the region of organic 
 life ceases at a limit 3000 feet lower, than that to which it extends 
 in the equinoctial portion of the Cordilleras. 
 
 178. Vegetation of the Andes. — The mountainous regions of 
 the Tropics present a further advantage in being that part of the 
 globe, as already mentioned, where the greatest possible variety 
 of impressions are produced by the contemplation of nature. In 
 the Andes of Cundinamarca, Quito, and Peru, furrowed by deep 
 barrancas, it is given to man to behold at once all the plants of 
 the earth, and all the stars of the firmament. There, at a single 
 glance, the beholder sees lofty feathered palms, humid forests of 
 bamboos, and all the beautiful family of musaceee, and, above 
 these tropic forms, oaks, meddlars, wild roses, and umbelliferous 
 plants, as in our European homes. There, too, both the celestial 
 hemispheres are open to his view, and when night arrives, he 
 sees displayed together the constellation of the Southern Cross, the 
 Magellanic clouds, and the guiding stars of the Bear, which 
 circle round the Arctic Pole. There the different climates of the 
 earth, and the vegetable forms of which they determine the 
 succession, are placed one over the other, stage above stage, and 
 the laws of the decrement of heat are indelibly written, on the 
 rocky walls and rapid slopes of the Cordilleras, in characters easily 
 legible to the intelligent observer. 
 
 N 2 179 
 
THE SURFACE OF THE EARTH. 
 
 Not only is the torrid zone by the abundance and luxuriance 
 of its organic forms most rich in powerful impressions, but it pre- 
 sents another and greater advantage, in the uniform regularity 
 which characterises the succession of its meteorological and organic 
 changes. The well marked lines of elevation which separate the 
 different forms of vegetable life, demonstrate in a striking manner 
 the same play of general and invariable laws, which govern the 
 celestial motions reflected in terrestrial phenomena. Thus, in the 
 burning plains which stretch nearly on the level of the sea in these 
 regions, we behold in profusion the families of bananas, of cyca- 
 dacese, and of palms, of which the number of species included in the 
 Floras * of the tropical regions, has been so wonderfully augmented 
 by modern botanic travellers. To these succeed, on the slopes of 
 the Cordilleras, in the mountain valleys, and in humid and shaded 
 clefts of the rocks, tree-ferns raising their thick cylindrical stems, 
 and expanding their delicate foliage, whose lace -like indentations 
 are seen projected against the deep azure of the firmament. 
 There, too, flourishes the cinchona, whose fever-healing bark is 
 deemed the more salutary, the oftener the trees are bathed and 
 refreshed by the light mists, which form the upper surface of the 
 lowest stratum of clouds. 
 
 Immediately above the region of the forests the ground is 
 covered with white bands of flowering social plants, small aralias, 
 thibaudias, and myrtle-leaved andromedas. The alp-rose of the 
 Andes, the magnificent befaria, forms a purple girdle round the 
 spiry peaks. On reaching the cold and stormy regions of the 
 Paramos, shrubs and herbaceous plants, bearing large and richly- 
 coloured blossoms, gradually disappear, and are succeeded by a 
 uniform mantle of monocotyledonous plants. This is the grassy 
 zone, where vast savannahs clothe the high tablelands and the 
 wide slopes of the Cordilleras, whence they reflect a yellow hue, — 
 savannahs, on which graze llamas and cattle descended from those 
 formerly brought from the Old "World. Trachytic rocks next 
 appear forcing the turf and rising high into those strata of the 
 atmosphere containing a less proportion of carbonic acid, and 
 supporting only plants of inferior organisation, such as the lichens, 
 the lecideas, and the many-coloured dust of the lepreria, which 
 forms small round patches on the surface of the stone. 
 
 Scattered patches of fresh fallen snow arrest the last feeble 
 traces of vegetation, and are succeeded by the region of perpetual 
 snow, of which the lower limit is distinctly marked, and undergoes 
 but little change. 
 
 * The collection of vegetable productiohs natural to a country is called 
 its flora, and that of the animals indigenous to it its fauna. 
 180 
 
TROPICAL VEGETATIOI?'. 
 
 The elastic subterranean forces strive, for the most part in 
 vain, to break through the snow-clad domes which crown the 
 ridges of the Cordilleras, but even where these forces have 
 actually opened a permanent channel of communication with 
 the outer air, either through crevices or circular craters, they 
 rarely send forth currents of lava, erupting more frequently 
 ignited scoriae, jets of carbonic acid gas, sulphuretted hydrogen, 
 and steam.* 
 
 179. Animals of the tropics. — corresponding variety is found 
 in the animal kingdom in these regions at the level of the sea ; 
 upon the plains which extend over the tropical regions are found 
 the varieties of monkeys, crocodiles, the boa- constrictor, rattle- 
 snake, jaguars, and macaws. Higher up, at a level rising from 
 5000 to 10000 fieet, at the base of the Andes, are found the ocelot, 
 the strutheo rea, and the duck. Higher still, the ape, the puma, 
 and the llama, and, in fine, about the snow-line, hawks, vultures, 
 bears, and the condor, which rises upon its vast wings above the 
 lofty summits of Chimborazo and Aconcagua. 
 
 180. The Himalayas are characterised, also, by animals dwell- 
 ing in a succession of stages one above the other. Thus, upon 
 the plains are found the tiger, the peacock, and the Bactrian 
 camel. Higher up the bat, the Cashmere goat, and the pheasant, 
 and just below the snow-line, the sheep, the yak, the pigeon, the 
 robin, &c. 
 
 181. The local character of a climate depends on the mean 
 temperature of the atmosphere and of the surface of the earth. 
 And this temperature itself must depend chiefly on the heat 
 imparted to the atmosphere and the earth by the sun. The solar 
 rays, in passing through the atmosphere to the earth, impart 
 to that very attenuated and transparent fluid an inconsiderable 
 quantity of heat, their chief thermal power being exerted on the 
 surface of the earth, which forms the base of the atmospheric 
 ocean. The earth, like all bodies, absorbs a certain proportion of 
 the heat thus transmitted to it, and what it fails to absorb it 
 reflects exactly as a surface would reflect light. The heat which 
 it reflects, not entering it, does not afiect its temperature, and it is 
 warmed exclusively by the portion it absorbs. This portion is so 
 considerable, that if it were uniformly diffused over the entire 
 surface of the earth, it would be sufficient to dissolve annually a 
 shell of ice 100 feet thick covering the entire globe. 
 
 182. Heat received from celestial spaces But besides the 
 
 heat received from the sun, the earth also receives a considerable 
 portion of heat from the surrounding firmament, in other words, 
 
 * * Humboldt's Cosmos, Introduction. 
 
 181 
 
THE SURFACE OF THE EARTH. 
 
 Trom the countless myriads of suns composing the stellar universe 
 wMch are seen nightly sparkling in the heavens ; and this latter 
 source of heat differs from that of the sun, inasmuch as all parts 
 of the earth are constantly exposed to it night and day, whereas 
 they are only exposed to the direct influence of the sun during 
 average intervals of twelve hours. 
 
 It has resulted from the experiments and observations of 
 M. Pouillet, that the quantity of heat thus received by the earth 
 from the celestial spaces is such, that if it were uniformly diffused 
 over the surface it would be sufficient to melt a shell of ice, 
 enveloping the earth, 85 feet thick. * 
 
 183. Why temperature of the earth is not indefinitely 
 increased — It may be asked, therefore, how it happens that if 
 the earth receive and absorb an annual quantity of heat so 
 enormous, its temperature is not raised to such a point as to be 
 incompatible with the continued existence of the organised world 
 upon it. It might be expected that the heat absorbed in the 
 torrid zone, being transmitted by the process of conduction 
 through the solid matter composing the earth to the colder regions 
 of the poles, would first dissolve all the ice there collected, and 
 then gradually raise the temperature of the polar regions, to 
 which the animal world would first take refuge flying from the 
 scorching region of the tropics, and which would become at the 
 same time the theatre of the present flora of the temperate and 
 tropical zones, and later would be raised to a temperature 
 destructive of all organisation. 
 
 Such a catastrophe is prevented, and the thermal condition of the 
 globe maintained within the necessary limits, by a remarkable pro- 
 perty with which matter has been endowed by its Maker, in virtue 
 of which all bodies possess the quality of thermal radiation, in the 
 exact proportion in which they are endowed with that of thermal 
 absorption. The heat, therefore, which every part of the surface 
 of the earth absorbs from the solar rays, it throws back by the 
 process of superficial radiation, and if the atmosphere were every- 
 where cloudless, the heat thus radiated back would pass into the 
 celestial spaces, and the atmosphere would then, in spite of the 
 solar rays passing through it, remain at a very low temperature. 
 
 184. Effect of clouds The existence of clouds, however, 
 
 modifies this. The heat radiated from the surface of the earth is 
 in a great degree intercepted, and prevented from escaping into the 
 celestial regions, by the clouds, which reflect and radiate it back 
 again to the earth through the lower strata of the atmosphere ; 
 and thus these thermal rays, being reverberated between the 
 
 * See Tract on Terrestrial Heat, Museum, vol. 3, p. 65. 
 
 182 
 
THERMAL CONDITION OF THE EAKTII. 
 
 clouds and the surface, warm tlie lower strata of the atmosphere 
 through which they are so frequently transmitted. 
 
 185. Effect of contact of air and earth. — But the atmosphere 
 also receives heat from the earth, by the contact of its lowest strata 
 with those parts of the terrestrial surface, which have a higher 
 temperature. When these lowest strata are thus warmed by 
 contact, they ascend as heated air does in a chimney, air having a 
 lower temperature flowing in to take their place. / 
 
 It is by these several means therefore, much more than by the 
 direct influence of the sun, that the temperature of the atmosphere 
 is maintained and regulated. 
 
 186. Thermal effects of an uniform surface. — If the whole 
 surface of the earth consisted of one homogeneous material, 
 whether solid or fluid, and were in one uniform condition, its 
 powers of reflection and absorption, and consequently its power 
 of radiation, would be everywhere the same. In that case 
 the thermal influence of the sun, governed by no other con- 
 ditions than those of its altitude and continuance above the 
 horizon, would necessarily be the same at all points of the same 
 parallel of latitude, since, at all such points, the sun's altitude 
 and the length of the day are necessarily the same. The equator 
 and each parallel of latitude would then be isothermal lines, a 
 word which expresses a line upon the surface of the earth, all 
 points of which have the same mean temperature. Not only 
 would the mean temperatures of all points on the same parallel be 
 the same, but the extreme temperatures of summer and winter 
 would likewise be the same. In other words, all places having 
 the same latitude would, under the conditions supposed, have 
 identically the same climate. They would have the same average 
 annual temperature, and would be subject to the same vicissitudes 
 of seasons. 
 
 In comparing parallel with parallel, the average annual tem- 
 perature, as well as the extremes of the seasons, would regularly 
 increase with, the latitude. 
 
 187. Why this regularity does not prevail — But the con- 
 ditions which would produce such climatic phenomena do not exist 
 on the terrestrial surface. Instead of consisting of one uniform 
 material, that surface is diversified, — first, by land and water ; 
 and secondly, the land itself is still more diversified in its 
 character, according as it is more or less clothed with vegetation, 
 and even where it is destitute of vegetation, it varies according 
 to the quality of the rocks or other strata which compose its 
 uncovered surface. The reflecting, absorbing, and therefore 
 radiating powers of the land, are infinitely diversified. In general 
 the foliage of vegetation is a powerful radiator, while the naked 
 
 183 
 
THE SURFACE OF THE EAETH. 
 
 soil, or rocks, are comparatively feeble radiators and stronger 
 reflectors. The water of tlie ocean, wMcli covers three-quarters 
 of the terrestrial surface, is much more uniform in its thermal 
 properties than the land. But even those properties of the ocean 
 are modified by the congelation which takes place on so vast a 
 scale in tne frigid zone. 
 
 All these circumstances combined, and many others which can 
 only be fully understood by a more profound study of physical 
 geography, render the actual climatic phenomena extremely dif- 
 ferent from those which would depend on the latitude alone, and 
 which would be developed on a globe the superficial materials of 
 which would be uniform. 
 
 The departure of the lines of equal, mean, and extreme tem- 
 peratures from the parallels of latitude, has been already ex- 
 plained in our Tract upon Terrestrial Heat, and it will not, 
 therefore, be necessary to insist further upon them here. 
 
 VU. — IN'DIA. 
 
 184 
 
MOUNTAINS. 
 
 MOUNTAINS. 
 
 188. Maps, and Globes in Relief. — Elementary instruction in 
 geography has been hitherto for the most part limited to the 
 description of the outlines of land and water. The varieties 
 of form depending on relief have been comparatively neglected. 
 This has arisen most probably from the difficulty of presenting to 
 the student visible representations of such forms. Maps and 
 globes, showing in moulded relief the inequalities of the land, 
 have indeed been constructed, and with suitable explanations may 
 be found useful to the teacher and the pupil. Independently, 
 however, of their cost, which is necessarily considerable, they are 
 subject to grave objection, owing to the enormous violation of 
 proportion between the vertical and the horizontal dimensions, 
 which they must necessarily exhibit. It has been explained else- 
 where, that the elevation of the most lofty mountain-summits does 
 not exceed the 1600th part of the Earth's diameter, and conse- 
 quently such a summit, if formed in relief in its just proportion 
 on a 16-inch globe, would be represented by a protuberance not 
 exceeding the hundredth part of an inch. All maps and globes, 
 therefore, presenting the inequalities of the land in moulded 
 relief, must, in order to render them perceptible at all, give the 
 vertical magnitude exorbitantly disproportionate to the horizontal 
 dimensions. When such illustrations are used for the purpose of 
 elementary instruction, the teacher should be careful to impress 
 upon the mind of the pupil this inevitable departure from the 
 natural proportions. 
 
 189. Johnston's Physical Maps. — The expedient adopted in 
 the physical maps of Mr. A. K. Johnston renders them exempt from 
 this objection, although the same vivid illustration of the super- 
 ficial inequalities is not presented by them. In these the plains, 
 valleys, and lowlands are coloured green, the elevated plateaux 
 and table-lands brown ; and the mountain-ridges and peaks are 
 distinguished by obvious marks indicative of their relative alti- 
 tudes, the actual heights being marked in numbers of Englisli 
 feet. The sea is also everywhere distinguished from the land by 
 its blue colour. As a physical illustration, these maps are there- 
 fore, as I conceive, as perfect as the nature of the subject of 
 instruction allows. 
 
 190. Mountain^anges not uniform. — Although each of the 
 great continental systems, which have been already described, is 
 characterised by a certain prevailing direction, it must not be sup- 
 posed that it follows one uniform and unbroken, course, or even 
 that it consists of a single uninterrupted series. They are, on 
 
 185 
 
THE SURFACE OF THE EAETH. 
 
 tlie contrary, liable to frequent changes of direction, are in many- 
 places discontinuous, and are subject to still greater irregularity 
 in both height and width. 
 
 191. Spurs — Each main ridge also throws out lateral ramifica- 
 tions at various angles with its general direction, called spurs. 
 Those are often themselves considerable chains of mountains, 
 throwing off secondary spurs parallel to the primary chain, or nearly 
 so. These subordinate ranges, intersecting each other at various 
 angles, and broken by valleys and ravines, form a' reticulation, 
 which usually covers a vast extent of country stretching out at 
 either side from the base of the principal chain. They decrease 
 gradually in their dimensions, both horizontal and vertical, with 
 their distance from the parent chain. Every one who has visited 
 the country on either side of the ranges of the Alps, the Pyrenees, 
 or Mount Atlas, wiU be familiar with these features. 
 
 192. Relief of the Sarth's surface. — Considering the Earth as 
 a globe formed of solid matter, subject to superficial inequalities, 
 and partially covered with water, the land must be regarded 
 merely as the more elevated parts rising out of the waters, which, 
 according to the common law of gravitation, are lodged upon the 
 lowest levels. The level parts of the land must be considered as 
 plateaux, table-lands, or terraces formed upon vast mountains, 
 the bases of which are at the bottom of the Ocean. 
 
 The mountains, in like manner, which rise from the surface of the 
 land, must be considered as only the highest peaks of those whose 
 bases are established upon the bottom of the deep, and the plains 
 around them, upon which they rest, as merely terraces or 
 plateaux forming steps, as it were, in ascending their acclivities. 
 
 In accordance with these views, it is found that systems of 
 mountains, whether they form continued chains, detached groups, 
 or isolated peaks, seldom have their bases upon a low level. On 
 the contrary, the plains upon which they stand are almost 
 always plateaux or tablelands at a considerable altitude above 
 the level of the sea. The heights of mountain-summits being 
 always expressed with relation to the level of the sea, it must 
 therefore be remembered, that in estimating heights above the 
 general level of the plains on which the mountains stand, it is 
 necessary to deduct the heights of such plains from the tabulated 
 heights of the mountains. 
 
 That this correction is of importance, will be comprehended 
 when it is remembered, that the heights of the tablelands upon 
 , which the great chains of mountains stand, above the level of the 
 sea, varies from 2000 to 12000 feet. Thus, for example, the 
 tabulated altitude of Kunchinjunga, the highest peak of the 
 Himalayas, and indeed the most loftv point hitherto discovered 
 186 
 
MOUNTAmS. 
 
 on the globe, is 28178 feet ; but tbe tableland of Thibet, on which 
 it stands, has an altitude of about 11000 feet, so that the height of 
 the peak above the level of the surrounding plain is only 
 17000 feet. 
 
 In like manner, the height of Mont Blanc is 15739 feet, but 
 the height of the Lake of Geneva being 1450 feet, and the base 
 of Mont Blanc being several hundred feet more, it follows that 
 the summit of Mont Blanc cannot be much more than 13000 feet 
 above the level of its base. 
 
 Erom the two examples here given, it will be apparent how 
 little relation the tabulated heights of mountains sometimes have, 
 to the appearance which they would present to an observer. The 
 highest peak of the Himalayas, measured from the level of the 
 sea, is nearly double that of Mont Blanc, and is sometimes there- 
 fore described as being a mountain, such as would be produced 
 by piling two like Mont Blanc one upon the other. Such an 
 illustration, nevertheless, is most inappropriate, as appears from 
 what has been just stated, since an observer of Kunchinjunga 
 must necessarily view it from a station about 11000 feet above 
 the level of the sea, while an observer of Mont Blanc can view it 
 from a station less than 2000 feet above that level. Mont Blanc 
 would, therefore, under these circumstances, have nearly as great 
 an apparent height as Kunchinjunga. 
 
 193. ISfFect of the contemplation of mountain scenery. — 
 The more the imagination and understanding are impressed with 
 the lofty and massive mountain ranges — as evidences of great ter- 
 restrial revolutions which the globe has undergone at distant epochs 
 of its history — as the limits of varying climates — ^as the lines of 
 separation forming the watersheds of opposite regions — and in 
 line, as the theatres of peculiar vegetation — the more necessary is 
 it to obtain a correct numerical estimate of their actual volume, 
 so as to demonstrate the comparative minuteness of their mass 
 beside that of the extensive platforms on which they stand. 
 
 194. The Pyrenees — Take, for example, the chain of the 
 Pyrenees, the area of whose base and whose mean elevation have 
 been determined with great precision. Let us suppose that this 
 entire mountain mass were spread equally over the whole surface 
 of France, and let it be required to determine what would be the 
 thickness of the stratum which it would then form. Nothing can 
 be more simple than such an arithmetical problem, and the result 
 of its solution is, that the whole surface of France would be raised 
 only 115 feet. 
 
 195. The Alps — In like manner, if the chain of the Alps were 
 levelled, and the material composing it*uniformly spread over the 
 whole surface of Europe, it would form a stratum only feet thick. 
 
 187 
 
THE SUEFACE OP THE EARTH. 
 
 196. Average height of continents. — Baron Humboldt, by an 
 elaborate calculation, obtained a pretty exact estimate of the 
 average height of the surface of the land, composing the principal 
 divisions of the world above the level of the sea. He found 
 that the average height of the land in Europe is 670 feet. In 
 North America, 748 feet. In Asia, 1132 feet; and in South 
 America, 1151 feet. 
 
 These results demonstrate that the land in the southern regions 
 is more elevated than in the northern. In Asia the low elevation 
 of the extensive plains or steppes of Siberia, is compensated by 
 the mountain masses between the parallels of 28^° and 40° lat., 
 extending from the Himalaya to the Kuenlun of Northern Thibet, 
 and to the Tianschian or Celestial Mountains. Some idea may be 
 formed from these calculations in what parts of the globe the 
 action of subterranean plutonic forces, as manifested in the 
 upheaval of continental masses, has been most intense. 
 
 197. Blew moiintain ranges possible. — There is no suf- 
 ficient reason," observes Humboldt, "why we should assume that 
 the subterranean forces may not, in ages to come, add new systems 
 of mountains to those which already exist, and of which Elie de 
 Beaumont has studied the directions and relative epochs. Why 
 should we suppose the crust of the earth to be no longer subject to 
 the agency, which has formed the ridges now perceived on its 
 surface ? Since Mont Blanc, and Monte Rosa, Sorata, Illimani, 
 and Chimborazo, the colossal summits of the Alps and the Andes 
 are considered to be amongst the most recent elevations, we are 
 by no means at liberty to assume that the upheaving forces have 
 been subject to progressive diminution. On the contrary, all 
 geological phenomena indicate alternate periods of activity and 
 repose ; the quiet which we now enjoy is only apparent ; the 
 tremblings which still shake the surface in every latitude, and in 
 every species of rock — the progressive elevation of Sweden, and 
 the appearance of new islands of eruption — are far from giving us 
 reason to suppose that our planet has reached a period of entire 
 and final repose." 
 
 THE OCEAN. 
 
 198. Greatest depth — ^While the aerial ocean invests the entire 
 surface of the globe, having a depth of from forty to fifty miles, 
 the liquid ocean under it, as already explained, covers only about 
 three-fourths of the solid surface, being deposited according to the 
 laws of gravitation, in the-lowest parts. According to the result 
 of soundings, already explained, the character of the solid surface 
 188 
 
THE OCEAN. 
 
 which, it covers is quite analogous to that which rises above its 
 surface, being similarly varied by hill and valley, mountain and 
 plain. The greatest depth of the ocean is still undiscovered. 
 The plumb-line, in one part of the Pacific Ocean, was let down to 
 the depth of 27600 feet by Sir James Ross without finding bottom. 
 It has been generally assumed, as most probable, that the greatest 
 depth of the ocean does not differ much from the greatest elevation 
 of the land above its surface, which being in round numbers five 
 
 V. — THE SPANISH PENINSULA. 
 
 miles, would show that the extreme difference of level of the solid 
 surface of the globe does not exceed ten miles, or about the 800th 
 part of its diameter. 
 
 199. Uses of the ocean — The vast collection of water forming 
 the ocean ministers in an infinite variety of ways to the main- 
 tenance of the organised world, and in none more so than in its 
 property of evaporation. It may be considered in a certain sense 
 as a vast apparatus of distillation, by which fresh water is 
 supplied in regulated quantity and suitable quality to all parts of 
 the land, and in these phenomena the mountains play a con- 
 spicuous part. 
 
 200. General system of evaporation and condensation. — It 
 
 is demonstrated in physics that when an aqueous solution is 
 exposed to the atmosphere, the pure water which forms the chief 
 
 189 
 
THE' SURFACE OF THE EARTH. 
 
 part of it will be converted into vapour at tlie surface in contact 
 with tlie air ; and the rate of such evaporation, other things being 
 the same, will be proportionate to the extent of the surface, the 
 temperature of the air in contact with it, and the superficial 
 temperature of the solution. 
 
 The water of the ocean is a solution of certain salts and alkaline 
 substances. The evaporation which takes place from its surface 
 afiects only the pure water, leaving the saline and other similar 
 constituents still dissolved in it. The pure aqueous vapour thus 
 taken into the atmosphere, rising to the more elevated strata, is 
 transported by atmospheric currents, and attracted by the mountain 
 summits and other elevated parts of the land, upon which it is 
 precipitated in the form of rain or snow, from which streams flow 
 down the declivities, discharging the functions of irrigation, and 
 thus contributing to the maintenance of animal and vegetable life 
 upon the land. 
 
 201. Climatic effects — Independently of the obvious advan- 
 tages which the ocean affords, as supplying the means of intercom- 
 munication by commerce between distant parts of the earth, it 
 also serves an infinite variety of purposes in the climatic economy 
 of the globe. It has been already shown that from the uniformity 
 of its physical qualities, it has a tendency to equalise and regularise 
 climate, so as to bring the isothermal lines into closer proximity 
 with the parallels of latitude. 
 
 202. Ocean currents. — Its liquid properties, however, com- 
 bined with the effects of temperature, render it further sub- 
 servient to the general equalisation of the temperatures of the 
 extreme zones, moderating the heat of the torrid and the cold of 
 the frigid. This is accomplished by the great ocean currents, 
 the existence, directions, and limits of which have been ascertained 
 by modern navigators. 
 
 These currents are classed as constant, periodical, and variable, 
 the two latter classes being determined chiefly by the influence of 
 the winds and tides. 
 
 203. Antarctic drift current — The constant currents which 
 are by far the most important, have their origin chiefly in the 
 southern frigid zone, from which a vast stream called the antarctic 
 drift current, pours its cold waters fijst northwards into the 
 Pacific and then eastwards towards the eastern coast of South 
 America. Striking upon the shores of Chili, opposite the island 
 of Juan Fernandez, it is diverted to the north, following the coast 
 of the South American continent, until it encounters the jutting 
 shores of Peru, by which it is turned westward, where it takes 
 the name of the equatorial current. 
 
 204. Its equatorial course. — From that point, following the 
 190 
 
OCEAN CURKENTS. 
 
 direction of the line westward, and passing among tlie islands of 
 the Indian Archipelago, it traverses the Indian ocean, and sweep- 
 ing round the Cape of Good Hope, turns northwards along the west 
 coast of Africa, until it encounters the shores of the Gulf of Guinea,, 
 which again divert it westward, where it resumes the name of the 
 equatorial current. Traversing the Atlantic, it arrives at tho 
 northern coast of South America, and enters the Caribbean Sea 
 through the chain of the West India islands, from which it arrives 
 in the Gulf of Mexico. 
 
 205. Gulf stream. — In this long course, after cooling the' 
 waters of the tropical ocean, its own temperature is at length 
 raised tp a high point, and in that thermal state it arrives in the 
 Gulf of Mexico. The direction of the current is there changed 
 by the southern coast, of North America, and it issues through 
 the channel between Cuba and Florida, flowing northward along 
 the coast of the United States, and about the 35th degree of lati- 
 tude turning north-east, it again traverses the Atlantic, dividing 
 its course into two branches, one directed between the British Isles 
 and Iceland to Spitzbergen in the Arctic ocean, and the other bv 
 the Azores and Madeira back to the coast of Morocco. 
 
 At the point where it issues from the Gulf of Mexico, the 
 current takes the well-known denomination of the Gulf stream. 
 Its temperature, as just stated, is so elevated that its existence 
 can readily be determined by navigators by means of the ther- 
 mometer. It becomes thus a means of transporting to the regions 
 of the northern frigid zone a portion of the tropical heat, so as to 
 produce the equalising effect already mentioned. 
 
 206. Course and limits of ocean currents evident. — The 
 currents of the ocean," observes Humboldt, " present a remarkable 
 spectacle, maintaining a nearly constant breadth. They cross the 
 sea in different directions, like rivers of which the adjacent 
 undisturbed masses of water form the banks. The line of 
 demarcation between the parts in motion, and those in repose, is 
 most strikingly shown in places where long bands of sea-weeds, 
 borne onward by the current, enable us to estimate its velocity. 
 Analogous phenomena are sometimes presented to our notice in 
 the lower strata of the atmosphere, when, after a violent storm, 
 the path of a limited aerial current may be traced through the 
 forest by long lanes of overthrown trees, whilst those on either 
 side remain unscathed." 
 
 207. Ocean rich in animal life. — Although the surface of the 
 ocean is less rich in animal and vegetable forms than that of 
 continents, yet when its depths are searched, perhaps no other 
 portion of our planet presents such fuUness of organic life. 
 Charles Darwin, in the agreeable journal of his extensive voyages, 
 
 191 
 
THE SUKFACE OF THE EARTH. 
 
 justly remarks, that our land forests do not harbour, so many 
 animals as the low wooded regions of the ocean, where the sea- 
 weed rooted to shoals, or long branches of fuci detached by the 
 force of the waves or currents, and swimming free, upborne by 
 air-cells, unfold their delicate foliage. The application of the 
 microscope still further increases our impression of the profusion 
 of organic life which pervades the recesses of the ocean, since 
 throughout its mass we find animal existence, and at depths 
 exceeding the height of our loftiest mountain chains, the strata 
 of water are alive with polygastric worms, cyclidise, and ophry- 
 dinae. Here swarm countless hosts of minute luminiferous animals, 
 mammalia, Crustacea, peridinea, and ciliated nereides, which, 
 when attracted to the surface by particular conditions of the 
 weather, convert every wave into a crest of light. The abundance 
 of these minute creatures, and of the animal matter supplied by 
 their rapid decomposition, is such, that the sea water itself becomes 
 a nutritious fluid to many of the larger inhabitants of the ocean. 
 
 208. Moral impressions. — If all this richness and variety of 
 animal life, containing some highly organised and beautiful forms, 
 is well fitted to aff'ord not only an interesting study, but also a 
 pleasing excitement to the fancy ; the imagination is yet more 
 deeply moved, by the impressions of the boundless and immeasur- 
 able which every sea voyage affords. He who awakened to the 
 inward exercise of thought, delights to build up an inner world 
 in his own spirit, fills the wide horizon of the open sea with the 
 sublime image of the Infinite ; his eye dwells especially on the 
 distant sea line, where air and water join, and where stars rise 
 and set in ever renewed alternations : in such contemplations 
 there mingles as with all human joy, '*a breath of sadness and 
 of longing." * 
 
 ♦ Humbolt's Cosmos, pp. 299, 303. 
 
 192 
 
0 
 
 SCIENCE AND POETRY. 
 
 1. Optical error in tlie fable of tlie Dog and tlie Shadow. — 2. Explanation 
 of the phenomena, — 3. Table showing the reflection at different 
 obliquities. — 4. Effect of looking down in still water over the 
 bulwark of a ship or boat. — 5. Effect of the varying distance of 
 the observers. — 6. Experiments with a basin of water. — 7. Expla- 
 nation of their effects. — 8. Scientific errors in Moore's Irish melody, 
 "Oh, had we some bright little isle." — 9. Demonstration of the 
 physical impossibility of what the poet supposes. — 10. Allusion in 
 Moore's Irish melody, " Thus when the lamp that lighted," explained. 
 — 11. Allusion in Moore's melody, "While gazing on the moon's 
 light." — 12. Shakspeare's allusion to the cricket. — 13. Moore's 
 allusion to the glowworm. — 14. Shakspeare on the economy of the 
 bee. — 15. Error of the phrase "blind as a beetle." — 16. Lines from 
 Campbell's "Pleasures of Hope." — 17. Error of the allusions to the 
 foresight of the ant — Lines from Prior. — 18. Verses from the Proverbs. 
 — 19. Celebrated description of the war-horse in Job. — 20. Unmeaning 
 language of the translation. — 21. Examination of the true meaning 
 of the original Hebrew by Dr. McCaul and Professor Marks. — 22 
 Interpretation by Gresenius. — 23. By Ewald. — 24. By Schultens. — 
 25. Correct meaning explained. 
 
 1. In" a former Tract we observed, that although the illustrations 
 and images drawn by poets from physical phenomena are generally 
 just and true, yet this is not always the case. They are some- 
 times altogether at variance with the principles of physics, and 
 involve suppositions totally incompatible with the laws of Nature. 
 The fable of the Dog and the Shadow, which has been handed 
 down through so many ages, diffused through so many languages, 
 and taught so universally in the nursery and in the school, was 
 given as an example of this.* 
 
 It was there stated, that this popular fable involved an optical 
 blunder, inasmuch as no reflection which could be supposed to 
 
 * See vol. vli., p. 
 
 LaFvDneu's Museum op Sciej?ce. 
 No. 113. 
 
 91. 
 
 o 
 
 193 
 
SCIENCE AND POETRY. 
 
 proceed from the water, could possibly be such as to make a real 
 dog behave itself as the dog of the fable did on that occasion. 
 Whether we were fully justified in this condemnation of the 
 ancient fable has been called in question, and some of our readers- 
 think that an image may be reflected from the surface of water, 
 under supposable circumstances, with sufficient vividness to justify 
 -<Esop, or whoever else was the original author of the fable. 
 
 Instead of stopping here to dispute this point, we shall consult 
 the benefit of our readers better by explaining the principles on 
 which it depends, and indicating some simple experiments which 
 we have ourselves tried, and which any of our readers may easily 
 repeat. 
 
 2. "When light falls upon a plane reflecting surface, the pro- 
 portion of the rays which are reflected is found by observation ta 
 be less and less, the more perpendicularly the rays are incident. 
 The actual proportion reflected at difierent degrees of obliquity,, 
 was determined by Bouguer, for different substances. The 
 results obtained by him in the cases of water and glass are given 
 in the following table, where the angle of incidence means the 
 angle which the incident ray makes with the perpendicular to the 
 reflecting surface. In the fourth column of the table is given for 
 each degree of obliquity the number of rays out of every thousand 
 which are reflected, and in the fifth column, the number which 
 are absorbed. 
 
 3. Table, shmclng the propoHion of Light incident on reflecting surfaces^ 
 which are regularly reflected at different angles of incidence. 
 
 Specimen of reflecting 
 Surface. 
 
 Angle of 
 Incidence. 
 
 No. of Kays 
 incident. 
 
 No. of Rays 
 regularly 
 reflected. 
 
 No. of Rays 
 irregularly 
 
 reflected and 
 absorbed. 
 
 I OOO 
 
 721 
 
 279 
 
 I ooo 
 
 211 
 
 789 
 
 I ooo 
 
 65 
 
 935 
 
 I ooo 
 
 18 
 
 982 
 
 lOOO 
 
 543 
 
 457 
 
 I ooo 
 
 300 
 
 700 
 
 I OOO 
 
 112 
 
 888 
 
 I ooo 
 
 25 
 
 975 
 
 Water 
 
 Glass 
 
 to 0° 
 
 to o 
 
 Now it appears from these results, that when a ray falls so 
 obliquely upon the surface of water, as to make with the per- 
 pendicular to the surface an angle of 75°, and, therefore, with the 
 surface itself an angle of 15°, nearly a fourth of all the incident 
 rays are reflected. Hence it is that the image of the banks of a 
 194 
 
THE DOG AND THE SHADOW. 
 
 lake or river, yiewed by an observer (fig., page 193,) stationed 
 at a considerable distance on the opposite side, arc very vivid, the 
 rays which produce vision in that case being those which fall with 
 great obliquity on the water. 
 
 Since it appears, however, that when the angle of incidence is 
 60°, and, therefore, the obliquity 30°, less than a fifteenth of the 
 entire number of incident rays are reflected by the water, the 
 image must become fifteen times less vivid. If, therefore, the 
 observer approach the opposite bank, as he may do in a boat, its 
 image reflected in the water will be less and less vivid ; or the 
 same efiect may be produced in some cases by taking a more 
 elevated position, without changing his distance. Indeed this 
 will give a more accurate result than the former, inasmuch as the 
 change of distance of the eye of the observer from the point of 
 reflection ought strictly to be taken into the account. 
 
 If the observer assume such a position, either by increasing his 
 elevation or by diminishing his distance, that the angle of inci- 
 dence shall be reduced to 30°, and, therefore, the obliquity to 60°, 
 no more than eighteen rays in a thousand will reach the eye ; and 
 if the obliquity be still further diminished, the number of reflected 
 rays will be much more inconsiderable. 
 
 Thus, by gradually diminishing the obliquity of the incident 
 rays by the change of position of the observer, the reflected 
 image, at first vivid, will be gradually more and more faint, until 
 at length it will cease to be perceptible. 
 
 4. If a person look down into still water, over the bulwark of 
 a vessel, he will not perceive any reflected image of his person ; 
 but if he lean over the gunwale of a boat, at a much less dis- 
 tance from the surface, he will perceive a faint reflection of his 
 person under certain circumstances. The cause of this is easily 
 explained. 
 
 The image formed by reflection is as far behind the reflecting 
 surface as the object is before it, and the intensity of the light 
 proceeding from such an image decreases in the same proportion 
 as the square of its distance from the observer increases. When, 
 therefore, the observer looks over the bulwark of a vessel, the 
 distance of his face from the surface of the water being, for 
 example, 12 feet, the distance of the image formed by reflection is 
 24 feet. The obliquity of the pencils which, proceeding from his 
 face, are reflected by the water is very small, the rays being nearly 
 perpendicular. Not more, therefore, than about two in every 
 hundred of such rays are reflected to his eye, and these diverge 
 from an image at 24 feet distance. The intensity of such reflected 
 light is, therefore, insufficient to produce a sensible efiect on the 
 retina. 
 
 0 2 195 
 
SCIENCE AND POETRY. 
 
 When the observer, looking over the gunwale of a boat, is 
 within two feet, for example, of the water, the image produced by 
 the lefiected rays is only four feet distant. The intensity of the 
 light is therefore greater, other things being the same, than in 
 the former case, in the proportion of the square of 4 to the square 
 of 24, or what is the same, in the proportion of 36 to 1. 
 
 5. But besides this, there is another circumstance to be taken 
 into account. The rays of the pencils which, diverging from the 
 person of the observer, are reflected by the water and received by 
 the eye, have a greater obliquity than in the former case, in the 
 same proportion nearly as that in which the distance of the observer 
 from the surface of the water is diminished, and consequently 
 according to the results given in the above table, a much greater 
 proportion of these rays will be reflected. On both these accounts 
 the image, which was imperceptible from the bulwark of the 
 vessel, is often perceptible from the gunwale of the boat. 
 
 In all such observations, however, there are numerous modify- 
 ing conditions which will vary the result in difi*erent cases. Thus, 
 if the water be clear and transparent, and the bottom strongly 
 illuminated, the light reflected from it will often predominate so 
 much over the rays which produce the image to the observer, that 
 this image will cease to be perceptible. 
 
 6. We have tried some simple experiments on this subject, the 
 results of which are instructive, and which may be easily repeated 
 by any of our readers. 
 
 Fill a basin with water, and place it near an open window, look 
 down from a height of five feet vertically above the surface of the 
 water. You will not perceive any trace of your o^vn image in the 
 water. Descend gradually towards the surface, and when your 
 face is at about four feet above it, the faintest conceivable image 
 of it will begin to be perceived. On approaching still closer, the 
 image will be a little, but a very little, more perceptible, but even 
 at the least distances the reflection will be so faint that it can only 
 be perceived by concentrating the attention upon it. 
 
 Let the basin be now surrounded with a sheet or any other 
 expedient, by which the light falling from the window upon the 
 water shall be excluded, but so that your face being above the 
 edge of the sheet shall be still illuminated, l^ou will then per- 
 ceive your reflected image with tolerable distinctness in tlie vrater, 
 even at a distance of four or five feet above its surface, and this 
 distinctness will be increased as the distance of your face above 
 the surface of the water is diminished. 
 
 7. The explanation of these effects is obvious. When the water 
 in the basin is exposed to the light of the window, the quantity 
 of tlie light reflected from the bottom of the basin to the eye of 
 
mooee's melodies. 
 
 the observer predominates so much, over the reflected rays which 
 form the image of his face, that this image ceases to be sensible ; 
 but when by surrounding the basin with a sheet or cloth, all light 
 proceeding from the window is excluded, no light arrives at the 
 eye of the observer except the rays which form the image of his 
 face, which image is therefore distinctly perceivable. 
 
 The basin of water may also be instructively applied to illus- 
 trate experimentally the results consigned to the above table by I 
 Eouguer. If it be placed on the floor or table between the observer 
 and the window, the observer standing at a considerable distance 
 from the basin, the rays proceeding from the window will be 
 strongly reflected from the surface, and a vivid image of the 
 window will be perceived in the usual inverted position in the 
 water. As the observer approaches it, the basin at the same time 
 being moved nearer to the window, the obliquity of the incident 
 rays to the surface of the water is gradually diminished, and the 
 vividness of the image will be found to decrease in a much more 
 rapid proportion, until at length the obliquity is so far diminished 
 that the image becomes altogether insensible. 
 
 Whether a reflection under any supposable conditions sufficiently 
 vivid to justify the ancient fable of the Dog and the Shadow is 
 probable, may be questioned, and we do not quarrel with some of 
 our readers who affirm this. We admit that the expressions used 
 by us in paragraph 18, p. 91, vol. 7, may have been too strong if 
 they are understood to imply that in no supposable case could any 
 image whatever be perceivable. We think nevertheless that a 
 dog, looking into a pond with meat in his mouth, the surface 
 of the pond being necessarily exposed to the broad liglit of day, 
 would not be likely to mistake the exceedingly faint reflection of 
 the meat for another and preferable piece of that aliment. 
 
 8. In one of his Irish Melodies, so familiar to all lovers of poetry 
 and music, Moore has the following lines — 
 
 *' Oh ! had we some bright little isle of our own, 
 In a bhie summer ocean far off and alone, 
 "Where a leaf never dies in the stiU blooming bowers, 
 And the bee banquets on through a whole year of flowers ; 
 ^Yhere the sun loves to pause 
 
 With so fond a delay. 
 That the night only draws 
 A thin veil o'er the day ; 
 Where simply to feel that we breathe, that we live, 
 Is worth the best joys that life elsewhere can give." 
 
 Now this is good poetry, but bad science. An " isle" in which 
 a leaf never dies," and in- which the flowers bloom through the 
 
 197 
 
SCIENCE AND POETRY. 
 
 year, must necessarily be within tlie tropics : a latitude to which 
 the succeeding lines about the "fond delay" of the sun, and the 
 night which only " draws a thin veil o'er the day," which pro- 
 duces, in other words, only a few hours of twilight, are utterly 
 inapplicable. 
 
 9. In tropical latitudes the variation of the length of the day is 
 very inconsiderable. It is a little more or a little less than twelve 
 hours, and that is all. The night is, consequently, subject to a 
 variation similarly limited. Instead therefore of the very long 
 days and the very short nights which the poet ascribes to his 
 'Msle" in the blue summer ocean, there would necessarily be 
 nights, the duration of which could never be much less than 
 twelve hours in any part of the year. 
 
 But this is not all. Instead of enjoying a constant nocturnal 
 twilight, so beautifully described by the poet as a veil drawn over 
 the day, the inhabitants of the tropics enjoy scarcely any twilight 
 at all, being plunged in nocturnal darkness almost immediately 
 after sunset. This arises from astronomical causes, which will be 
 very easily understood. 
 
 Twilight is produced by the reflection of the sun's light from 
 that part of the visible atmosphere upon which the sun continues 
 to shine after sunset until its depression below the horizon 
 amounts to about 18°. Now it is apparent, that the more nearly 
 perpendicular to the horizon the diurnal motion of the sun is, the 
 sooner will its orb attain this depression of 18°. In the higher 
 latitudes, where the celestial pole is not very far removed from 
 the zenith, the sun is carried round in a diurnal circle, making 
 a very oblique angle with the horizon; consequently, after it 
 sets, its depression below the horizon increases very slowly, and 
 a long interval elapses before the depression amounts to 18°. In 
 some latitudes at the season of Midsummer it is not so much 
 as 18° even at midnight; and in such places the poet might very 
 truly say,— 
 
 ' " The night only draws 
 
 A thin veil o'er the day." 
 
 But the latitudes in which this can take place are very differ- 
 ent indeed from those in which 
 
 " a leaf never dies in the still blooming bowers, 
 And the bee banquets on through a whole year of flowers." 
 
 The distance of the celestial pole from the northern point of 
 the horizon being always equal to the latitude of the place, as may 
 be seen by reference to our Tract on Latitudes and Longitudes, 
 the depression of the sun below the horizon at midnight will be 
 found by subtracting the latitude of the place from the sun's 
 198 
 
Moore's melodies. 
 
 |)olar distance. Now the sun's polar distance at Midsummer is 
 <j6^°, and in order that its depression at midnight should not 
 •exceed 18°, the latitude of the place must at least be equal to 
 •66|°, diminished by 18°, that is, 48^°. 
 
 It follows, therefore, that an entire night of twilight can only- 
 take place at latitudes higher than 48 1°. But to produce the 
 effect expressed by the poet, a twilight should be maintained 
 much stronger than that characterised by the scientific sense of 
 the term. A twilight which would be only a " thin veil drawn 
 over the day," would be such as can be only witnessed in lati- 
 tudes like those of Norway and Sweden, the northern parts of 
 Scotland, the Orkneys, &c. 
 
 In tropical latitudes, on the contrary, the celestial pole has an 
 altitude less than 23^°, and the diurnal path of the sun makes 
 with the plane of the horizon an angle greater than 66^°. After 
 •sunset, the sun therefore descends very rapidly, and the more 
 rapidly the nearer the place is to the line. At the line itself the 
 sun attains the depression of 18° in about seventy- two minutes 
 after sunset ; and although the twilight in the scientific sense of 
 the term would not terminate till then, it comes to a close much 
 sooner in the poetic sense of the " veil drawn o'er the day." In 
 short, an almost sudden darkness succeeds sunset, and, in like 
 manner, sunrise succeeds as suddenly to the darkness of night. 
 
 In a word, the poet, in the beautiful lines cited above, has com- 
 bined incompatible astronomical and climatological conditions. The 
 perpetual summer necessarily infers tropical latitude, while the short 
 and twilighted night infers a high, not to say a polar latitude. 
 
 It would, perhaps, be deemed hypercritical to examine how far 
 the naturalist would justify the poet in his allusion to the industry 
 •of the bee in a tropical climate. The honey-bee, which no doubt 
 was the insect alluded to by the poet, is, for the most part, eon- 
 fined to ultra- tropical latitudes. Since, however, there are certain 
 species of this insect found in the lower latitudes, it may be 
 admitted that the poet has, at least in this point, a locus standi. 
 
 Having had the pleasure of the personal acquaintance of the 
 author of the Melodies, I once pointed out to him these scientific 
 incompatibilities in his lines. He replied good-humouredly, that 
 it was lucky when he wrote the song that such inconsistencies did 
 not occur to him ; for, if they had, some pretty thoughts would 
 inevitably have been spoiled, since he could not have been brought 
 knowingly to take such liberties with the divinities of Astronomy 
 -and Geography. 
 
 10. The allusion and imagery which Moore loved to seek 
 in certain parts of physical science were generally much more 
 
 199 
 
SCIENCE AND POETRY. 
 
 consistent with physical truth, without being less beautiful, than 
 that which we have quoted above. 
 
 How happily, for example, did he avail himself of that beautiful 
 property of the iris by which it accommodates the eye to greater and 
 less degrees of light, enlarging the pupil when, the light is faiut, 
 »and contracting it when it is intense. 
 
 The iris, as is well known, is the coloured ring which sur- 
 rounds the dark spot in the middle of the eye ; this dark spot 
 being not a black substance, but a circular orifice through which 
 the light is admitted to the membrane lining the posterior part 
 of the internal chamber of the eye. This circular orifice is called 
 the pupil, the retina being the nervous membrane which pro- 
 duces the visual perceptions. These, with other particulars of the 
 structure of the eye, will be found fully explained in our Tract on 
 that subject. 
 
 The iris which surrounds the pupil has a certain power of con- 
 traction and expansion, which is produced by the action upon it of 
 proper muscles provided for that purpose. 
 
 The quantity of light admitted through the pupil to the retina 
 is increased or diminished in the proportion, of the area of the 
 pupil, which increases and diminishes in proportion to the square 
 of its diameter ; a very small variation of which therefore pro- 
 duces a very considerable proportionate variation of the quantity 
 of light admitted. 
 
 If a person, after remaining for some time in a room dimly 
 lighted, pass suddenly into one which is strongly illuminated, he 
 'svill become instantly sensible of pain in the retina, and will 
 involuntarily close his eyes. After a short time, however, he will 
 be enabled to open them and look around with impunity. 
 
 The cause of this is easily explained. In the dimly lighted 
 room the pupil was widely expanded to collect the largest quantity 
 possible of the faint light, so that a sufficient quantity might be 
 received by the retina to produce a sensible perception of the 
 surrounding objects. On passing into the strongly illuminated 
 room the expanded pupil admits so much of the intense light as 
 to act painfully on the retina, before there is time for the iris to 
 adjust itself so as to contract the aperture of the pupil. After 
 a short interval, however, this adjustment is made, and the area 
 of the pupil being diminished in the same proportion as the 
 intensity of the light to which it is exposed, has been augmented 
 in passing from the one room to the other, the action upon the 
 retina is proportionally mitigated, so that the eye can regard 
 without pain the surrounding objects. 
 
 The reverse of all this takes place when the eye suddenly 
 passes from strong to feeble illumination. The pupil contracted 
 200 
 
mooee's melodies. 
 
 when exposed to the strong light is not sufficiently open to admit 
 the rays of feeble light necessary to produce visual perception^ 
 and for some time the surrounding objects are invisible. When^ 
 however, the proper muscular apparatus has had time to act upon 
 the iris so as to enlarge the pupil, the rays are admitted in greater 
 quantity, and the surrounding objects begin to be perceived. 
 These phenomena are beautifully expressed by the lines of 
 Moore : — • 
 
 " Thus when the lamp that Kghted 
 The traveller, at first goes out, 
 He feels awhile benighted, 
 
 And lingers on in fear and doubt ; 
 
 *' But soon the prospect clearing, 
 
 In cloudless starlight on he treads. 
 And finds no lamp so cheering 
 
 As that light which Heaven sheds." 
 
 Nevertheless there is a point in this Avhich demands some ex- 
 planation. It is implied in these lines that the source of nocturnal 
 illumination is chiefly, if not exclusively, starlight. This has 
 been in a great measure disproved in some memoirs published by 
 Arago in the " Annuaire du Bureau des Longitudes," in which he 
 shows that there must be some other source of nocturnal illumi- 
 nation than that of the stars. On nights, for example, which are 
 thickly clouded there is sometimes a stronger light than on those 
 in which the firmament is clear and serene. From this and other 
 circumstances Arago argues that there must be some power of 
 illumination in the clouds or in the atmosphere independently of 
 the light which proceeds from the stars. This is a point, however, 
 the full development of which would require more space and 
 time than we can spare for it on the present occasion. 
 
 11. In another of Moore's poems we find the following beautiful 
 lines : — 
 
 While gazing on the moon's light 
 
 A moment from her smile I turn'd, 
 
 To look at orbs that, more bright, 
 
 In lone and distant glory burn'd. 
 
 But too far 
 
 Each proud star, 
 
 For me to feel its warming flame. 
 
 Much more dear, 
 
 That mild sphere. 
 
 Which near our planet smiling came, 
 * * * * 
 
 Thus, Mary, be but thou my own ; 
 
 While brighter eyes unheeded play, 
 I'll love those moonlight looks alone, 
 
 That bless my home and guide my way," 
 
 201 
 
SCIENCE AND POETRY. 
 
 This is not only beautiful poetry, but sound astronomy. The 
 distances of the stars are many hundreds of millions of times 
 greater than that of the moon, but their actual splendour is in 
 many cases greater than that of the sun. Thus it has been shown 
 by calculations made upon observations which appear to admit of 
 no doubt, that the star Sirius, commonly called the Dog-star, is a 
 sun 146| times more splendid than that which illuminates our 
 system. Its distance, however, is so enormous that the actual 
 light which it sheds upon our firmament is less than the five 
 thousand millionth part of the sun's light. 
 
 Another star, which is the principal one in the constel- 
 lation of the Centaur, has been ascertained to be a sun whose 
 splendour is 2-} times greater than that of ours, but owing 
 to its enormous distance the light which it sheds in our 
 firmament is twenty-two thousand million times less than that 
 of the sun. * 
 
 Sir John Hersehel compared the light shed by this star from 
 our firmament, and found by exact photometric measurement 
 that it was 27408 times less than the light of the full moon. 
 
 12. Shakspeare imputes to the cricket the sense of hearing — 
 I will tell it softly, young crickets shall not hear me. 
 
 This was long considered as a scientific blunder on the part of 
 the poet, the most eminent naturalists having maintained that 
 insects in general have no sense of hearing. Brunelli, an Italian 
 naturalist, however, has demonstrated that the cricket at least 
 has that sense. Several of these insects, which he shut up in a 
 chamber, continued their usual crinking or chirping the whole 
 day except at moments when he alarmed them by suddenly 
 knocking at the door. The noise always produced a temporary 
 silence on their part. He contrived to imitate their sounds so well 
 that the whole party responded in a chorus, but were instantly 
 silenced on his knocking at the door. 
 
 He also made the following experiment. He confined a male 
 cricket on one side of his garden, while he put a female on the 
 other side at liberty. The moment the belle heard the crink of 
 her beau she showed no coyness, but immediately made her way 
 to him. 
 
 13. The female glowworm, which emits the phosphorescent light, 
 familiar to all who have dwelt in warm climates, remains com- 
 paratively stationary to await the approach of her mate, attracted 
 
 * Lardner's Astronomy, pp. 749, 752. 
 
 202 
 
SHAKSPEARE ON THE BEE. 
 
 to her by the light which she holds out to him, a circumstance of 
 which Moore has availed himself with his usual felicity : — 
 
 ''Beautiful as is the light 
 The glowworm hangs out to allure 
 Her mate to her green bower at night." 
 
 14. The well-known economy of the bee was never more beauti- 
 fully described than by Shakspeare, who puts the following 
 comparison into the mouth of the Archbishop of Canterbury : 
 
 "True ! therefore doth Heaven divide 
 The state of man in divers functions, 
 Setting endeavour in continual motion ; 
 To which is fixed, as an aim or butt, 
 Obedience : for so work the honey bees ; 
 Creatures that, by a rule in nature, teach 
 The act of order to a peopled kingdom. 
 They have a king, and officers of sorts : 
 "Where some, like magistrates, correct at home ; 
 Others, like merchants, venture trade abroad ; 
 Others, hke soldiers armed in their stings. 
 Make boot upon the summer's velvet buds ; 
 Which pillage they with merry march bring home 
 To the tent royal of their emperor ! 
 Who, busied in his majesty, surveys 
 The singing masons building roofs of gold ; 
 The civil citizens kneading up the honey ; 
 The poor mechanic porters crowding in 
 Their heavy burdens at his narrow gate ; 
 The sad-eyed justice, with his surly hum. 
 Delivering o'er to executors pale 
 The lazy yawning drone." 
 
 Henry V., Act. I., Scene 2. 
 
 15. The phrase as blind as a beetle," is as false as it is fami- 
 liar. In the rapid flight of this insect in the evenings of summer, 
 it often strikes the face of those who walk abroad, and hence is 
 erroneously inferred to be blind. 
 
 Collins describes this insect in the well-known lines of his 
 Ode to Evening : — 
 
 "Now air is hushed, save where 
 The beetle winds his small but sullen horn, 
 As oft he rises midst the twilight path. 
 Against the pilgrim borne in heedless hum." 
 
 The poet, it will be observed, avoids falling into the popular 
 error of imputing blindness to the insect. 
 
 203 
 
SCIENCE AND POETEY. 
 
 16. In Campbell's immortal poem, tiie Pleasures of Hope, we 
 find the following lines : — 
 
 " Angel of Life ! thy glittering wings explore 
 Earth's loneliest bounds, and Ocean's wildest shore. 
 Lo ! to the wintry winds the pilot yields 
 His bark careering o'er unfathom'd fields; 
 Now on Atlantic waves he rides afar, 
 Where Andes, giant of the western star, 
 "With meteor standard to the winds unfurl' d, 
 Looks from his throne of clouds o'er half the world." 
 
 Althougb it is difficult to assign a limit to the degree of exag- 
 geration allowed by the licence of poetry, it is quite clear that 
 there is some such limit, and we apprehend that if these lines, 
 so admirable as poetry, be curiously examined by the light of 
 science, they will scarcely be considered as falling within such 
 limit. 
 
 We are to imagine with the poet the genius of the Andes 
 enthroned upon the most lofty peak of that chain, looking round 
 him at the hemisphere, on the middle of which his throne rests. 
 To behold from such a position "half the world," would be 
 a manifest optical impossibility, however elevated his seat might 
 be. But if his range of view could in any degree approximate to 
 half, or even to a quarter of the globe, the exaggeration might 
 be allowed to pass. Let us see, however, what would be the 
 utmost possible range of view which could be obtained by an 
 observer placed upon the apex of the most lofty cone of the 
 Andes, supposing the surrounding mountains of less elevation not 
 to interrupt his general view of the earth's surface. 
 
 The most lofty peak of the Andes is that of Aconcagua, which 
 rises immediately above Valparaiso, overlooking the Pacific Ocean. 
 The extreme height of this summit is 23910 feet. Now let us 
 see what would be the extreme range of view from such an 
 elevation ; and in making this calculation we shall, contrary to 
 
 our custom, introduce its mathe- 
 Fig. 1. matical details, so as to inspire 
 
 71 T t' t" our readers \yith greater confidence 
 
 ""^k/ in the result. Let us suppose the 
 semicircle here indicated to repre- 
 sent the section of the hemisphere, 
 near the middle of which the sum- 
 mit of the mountain is placed. 
 Let 0 represent the base, and t 
 the summit of the mountain. If a line t z be drawn touching 
 the earth, the point z will be the limit of the range ,/)f view of 
 an observer looking from t in the direction of t z, and the 
 204 
 
Campbell's pleasures of hope. 
 
 terrestrial arc z o will therefore represent the radius of the 
 circle round the observer, which will be seen visible to him. In 
 short, it will represent his terrestrial horizon, which the poet 
 in the lines quoted assumes to be half the globe. By calculatinf^ 
 the arc z 0, the degree of exaggeration in the poetical illusion will 
 be rendered apparent. 
 
 The height of the peak of Aconcagua, reduced to geographical 
 miles, is 3*935. The length, a z, of the earth's semi- diameter, 
 also expressed in geographical miles, is 3438, and, consequentlv, 
 of the line a t will be 3438 + 3-935 = 3441-935. Let the ter- 
 restrial arc z 0 be expressed by a, we shall then have 
 
 A z 3438000 
 
 Cos. A = — = 
 
 AT 3441935 
 
 To compute the value of a, we shall have, therefore — 
 
 Log. 3438000 = 6.5363059 
 Log. 3441935 = 6-5368021 
 
 Log. Cos. A = 9-9995038 
 
 A = 2° 44' 18" = 164-3 miles. 
 
 It appears, therefore, that the range of view round such an 
 observer would be confined mthin a radius of 164 geographical 
 miles, whereas half the world," supposing it to be spread out in 
 a circle under the eye of the observer, would be measured by a 
 radius of 90 X 60, or 5400 miles, so that half the world would be 
 measured by a radius more than thirty-two times that which 
 would actually limit the view of Campbell's giant of the western 
 star." "We admit, however, that the task is rather an ungracious 
 one, which consists in thus cutting down the splendid imagery of 
 Campbell's poetry to the level of the severe limits of scientific 
 truth, and if we do so, it is more for the sake of exercising our 
 readers in physical enquiry, and habituating them to mathema- 
 tical precision, than with any intention of depreciating poetic 
 beauties of wiiich we are as sensible as others. 
 
 17. No notion is more prevalent, respecting the insect economy, 
 nor more frequently embodied in the imagery of poets and in the 
 eloquence of moralists, than the industry and foresight imputed 
 to the ant : — 
 
 — "Tell me, why the ant, 
 'Midst summer's .plenty, thinks of winter's want, 
 
 constant jonrnies careful to prepare 
 Her stores, and, bringing home the corny ear, 
 
 205 
 
SCIENCE AND POETRY. 
 
 By wtab instruction does slie bite tbe grain. 
 Lest, hid in earth, and taking root again, 
 It might elude the foresight of her care ? " 
 
 Prior. 
 
 It has been ascertained, however, that these instincts are 
 erroneously imputed to the ant. That insect passes the winter in 
 a torpid state, and does not lay up any store of provisions. Still 
 less does it take any such precautions as those commonly im- 
 puted to it, of biting off the ends of the grains which it lays in 
 store, to prevent them from germinating. It is supposed that 
 this error may have arisen from the insect being observed to 
 carry about their young in the pupa state, in which they have 
 some resemblance to a grain of corn, and also from their being 
 observed to gnaw off the end of the sheath which encloses the 
 pupa, in order to liberate the insect, after it has attained its perfect 
 state, from its confinement. ' 
 
 18. The words of Solomon respecting this insect, whicli occur in 
 Proverbs, vi. 6, 7, 8, are well known : — 
 
 6. Go to the ant, thou sluggard ; consider her ways and be wise. 
 
 7. Which having no guide, overseer, or ruler, 
 
 8. Provideth her meat in the summer, and gathereth her food in the 
 harvest. 
 
 If the original Hebrew word, which has been here translated by 
 the Saxon ant, properly signifies the European insect of that 
 name, these verses of Solomon would undoubtedly involve an 
 error in zoological history ; but that cannot be affirmed until the 
 habits and manners of other species of the insect inhabiting 
 warmer climates have been examined and ascertained. For 
 although during the cold winters incidental to this climate, the 
 ants remaining in a torpid state do not need food, yet in warmer 
 regions, where they are probably confined to their nests during 
 the rainy season, a store of provisions may be necessary for them. 
 This supposition has been to a great extent verified by the dis- 
 covery made by Colonel Sykes, at Poonah, in India, of a species of 
 ant, which he denominates Atta providens, which store up the 
 seeds of a kind of grass called panicum, at the time they are ripe 
 in January and February, which they expose on the outside of 
 their nests to the sun in the warm season, for the purpose of 
 drying them after they have been wetted by the rains of the 
 Monsoon. Such measures cannot be explained, except by the 
 supposition that these seeds are destined for food, and though 
 there is no recorded instance of ants feeding on any vegetable 
 substances, except such as are saccharine, yet, all experience 
 proves how constantly in entomology, exceptions to general laws 
 206 
 
PROVERBS — JOB. 
 
 are presented, and there seems to be good reason to believe tbat 
 this is one of them.* 
 
 19. Every reader who is duly sensible of the sublime poetry of 
 certain parts of the Hebrew Scriptures will be familiar with the 
 following splendid description of the war-horse in the Book of 
 Job, xxxix. 19 : — 
 
 19. Hast thou given the horse strength ? hast thou clothed his neck 
 with thunder ? 
 
 20. Canst thou make him afraid as a grasshopper? the glory of his 
 nostrils is terrible. 
 
 21. He paweth in the valley, and rejoiceth in his strength : he goeth 
 on to meet the armed men. 
 
 22. He mocketh at fear, and is not affrighted ; neither turnetb he back 
 from the sword. 
 
 23. The quiver rattleth against him, the glittering spear and the 
 shield. 
 
 24. He swalloweth the ground with fierceness and rage ; neither 
 believeth he that it is the sound of the trumpet. 
 
 52. He saith among the trumpets, Ha, ha ; and he smelleth the battle 
 afar off^ the thimder of the captains, and the shouting. 
 
 20. In reading these verses, one is so dazzled with their splen- 
 dour that it is difficult to submit them to the cold test of physical 
 truth. Nevertheless, it has always appeared to us, that the 
 second member of the first verse above quoted is, as translated, 
 destitute of all meaning. To clothe an object with thunder would 
 be to clothe it with a sound, which obviously is destitute of all 
 meaning either literal or metaphorical. It might seem as though 
 the allusion intended in the original of the passage might have been 
 to lightning and not to thunder. One can conceive the waving 
 and flashing of the mane of the war-horse fairly enough imaged 
 by lightning, especially when considered in connection with the 
 roar of the battle-field and ''the thunder of the captains," so 
 finely described in a succeeding verse. If the original Hebrew 
 term which has been translated by the word thunder could bear 
 the signification of lightning, the objection here advanced woidd 
 be removed. 
 
 To say that a thing is clothed with a sound reminds one of an 
 anecdote to which we have alluded on a former occasion. A 
 bUnd man being asked what idea he had of the colour scarlet, 
 replied that he believed he had a very clear notion of it, for that 
 it was just like the sound of a trumpet. 
 
 21. Thinking it highly probable that the blemish which I have 
 
 * Trans. Ent. Soc, London. Vol. ii. p. 211. 
 
 207 
 
SCIENCE AND POETRY. 
 
 here indicated was attributable to the translators, ratber than 
 the author, of the book of Job, I have had recourse to the original 
 Hebrew ; and desiring on such a point to be supported by higher 
 authority than I can myself lay claim to, I requested the aid of 
 two eminent Hebraists, Dr. Alexander McCaul, of King's College, 
 and the Rev. Professor Marks, of University College, London, 
 both of whom have favoured me with their opinions and sug- 
 gestions on the subject ; and, as they do not materially differ, 
 there can be no doubt that their interpretation is substantially 
 correct. It appears, as I anticipated, that the translation is 
 faulty ; but, on the other hand, the Hebrew word which has been 
 translated thunder never means lightning. 
 
 22. Gesenius says that the primitive sense of the term used is 
 tremor, or trembling, being derived from the verb Raam, which 
 signifies to tremble. In verse 19, he says, that it has the 
 primary sense, tremor, and that it is used poetically for the mane 
 of a horse, as in the Greek (p6^r}. Here, however, are his words 
 from the Thesaurus : 
 
 nop f. 1, tremor ; poet, pro juba equi, quoe in equis nobilioribus 
 propter cervicis obesitatem contremiscit, unde gr. <p6fiT}, juba, a 
 <p6fios. (Job. xxxix. 19.) " 
 
 23. The famous Ewald, the other great authority in Hebrew, 
 in his ''Poetische Biicher des Alten-Bundes," gives the same 
 sense, and translates the word by the German Zittern, trembling. 
 Both understand the trembling mane, and therefore find no 
 allusion to thunder or lightning. The word is by none inter- 
 preted lightning, and cannot have that meaning. The LXX have 
 <p6fiov, tremor, which Gesenius supposes to be equivalent to (p6^rt, 
 mane. Symmachus has KXayyrjv. Theodotion, xp^h-^'^^^f^^^y which 
 sense is also given by the Vulgate, Hinnitum. The moderns, 
 who prefer this sense, take **neck" as poetic for 'Hhroat," or 
 explain the thunder of the sound of the long shaking mane. 
 
 24. Schultens translates the word ''tremore alacri," (with 
 rapid quivering). Parkhurst translates the word thus, " With 
 the shaking mane." 
 
 25. On the whole, therefore, it appears that the English version 
 of the second member of v. 19, chap, xxxix. is incorrect. Hast 
 thou clothed his neck with thunder ? " is not the sense of the 
 original Hebrew, which would be correctly rendered thus, *' Hast 
 thou clothed his neck with a shaking (or flowing) mane ?" 
 
 •203 
 
EDITED BY 
 
 DIONYSIUS LARDNER, D.C.L., 
 
 . formerly Professor of Natural Philosophy and Astronomy in University College, London 
 
 ILLUSTRATED BY ENGRAVINGS ON WOOD 
 
 VOL. X. 
 
 LONDON: 
 WALTON AND MABEELT, 
 
 UPPER GOWER STREEi; AND IVY LANE, PATERNOSTER ROW. 
 1869. 
 
 [The riglii vf Translation is reserved.'\ 
 
LONDON : 
 
 BRADBURY, EVANS, AND CO., PRINTERS, WHITEFRIARS. 
 
CONTENTS. 
 
 THE BEE. 
 
 ITS CHARACTER AND MANNERS. 
 
 PAGE 
 
 CiiAP. I. — 1. Moral suggested by economy of nature. — 2. Antiquity 
 of apiarian researches — Hebrew scriptures — Aristomachus — 
 fbiliscus — Aristotle — Virgil. — 3. Modern observers. — 4. Huber. 
 — 5. His servant Burnens — curious history of his blindness. — 
 6. His wife and son. — 7. Pursuit of his researcbes. — 8. Structure 
 of insects. — 9. Plan of their anatomy. — 10. Hymenoptera, — 11. 
 Varieties of bees. — 12. Hive-bee. — 13. The queen — her numerous 
 suitors. — 14. Her chastity and fidelity. — 15. Her fertility. — 16. 
 Her first laying. — 17. Eoyal eggs. — 18. Royal chamber. — 19. 
 Effect of her postponement of her nuptials. — 20. The drones. — 
 21. The workers. — 22. Structure and members of the bee. — 
 23. Mouth and appendages. — 24. Use of proboscis. — 25. Struc- 
 ture of tongue. — 26. Honey-bag.— 27. Stomach. — 28. Antennse. 
 —29. Wings.— 30. Legs.— 31. Feet.— 32. Sting.— 33. Organs 
 of fecundation and reproduction. — 34. Number of eggs produced 
 by the queen .1 
 
 Chap. II. — 35. This fecundity not anomalous. — 36. Bee arcbitec- 
 ture. — 37. Social condition of a people indicated by their buildings. 
 — 38. This test applied to the bee. — 39. Individual and col- 
 lective habits. — 40. Solitaiy bees. — 41. Structure of their nests. 
 — 42. Situation of nests. — 43. Anthidium manicatum, — 44. 
 Expedient for keeping nest warm. — 45. Clothier bee. — 46. Car- 
 penter bee.— 47. Mason bee. — 48. Expedient to protect the nest. 
 — 49. Upholsterer bee. — 50. Hangings and carpets of ber rooms. 
 — 51. Leaf-cutter bees. — 52. Method of making their nest. — 53. 
 Process of cutting the leaves. — 54. Hive-bee. — 55. Structure of 
 the comb. — 56. Double layer of cells. — 57. Pyramidal bases. — 
 58. Illustrative figures. — 59. Single cells. — 60. Combination of 
 cells. — 61. Great advantages of hexagonal form. — 62. Economy 
 
CONTENTS. 
 
 PAGE 
 
 of space and material. — 63. Solidity of structnj?». — 64. Geome- 
 trical problem of the comb solved. — 65. Expedient to secure the 
 sides and bases of the cells .17 
 
 Chap. III. — 66. Drone cells and worker cells. — 67. Store cells.— 
 68. Construction of combs. — 69. Wax-makers also produce 
 lionoy. — 70. First operation of the wax-makers. — 71. Process of 
 the foundress. — 72. Kneading the wax. — 73. Formation of first 
 wall.— 74. Correction of mistakes. — 75. Dimensions of first wall. 
 — 76. Operations of the nurses. — 77. Bases of cells. — 78. Wax- 
 makers resume their work — Completion of pyramidal bases. 
 — 79. Pyramidal partition. — 80. Formation of cells. — 81-82. 
 Arrangement of combs. — 83. Sides not parallel. — 84. Process 
 not merely mechanical. — 85-86. Process of construction. — 87. 
 Labour successive. — 88. Dimensions of cells. — 89. Their number. 
 — 90. Bee-bread. — 91. Pap for young. — 92. Food adapted to 
 age. — 93. Transformation. — 94. Humble-bees — females. — 95. 
 Their nursing workers. — 96. Transformation. — 97. How the 
 temperature of the cocoons is maintained. — 98. Anecdote related 
 by Huber. — 99. Remarkable care of the nurses. — 100. Heat 
 evolved in respiration by the hive-bee. — 101. Cross alleys con- 
 necting the streets. — 102. First laying of the queen in Spring. — 
 103. Her royal suite.— 104. The eggs 33 
 
 Chap. IV. — 105. The larvae. — 106. Transformation of worker nymph. 
 — 107. Worker cells. — 108. Treatment of a young worker. — 
 109. Of the drone.— 110. Drone nymph.— 111. Royal cell and 
 nymph. — 112. Its treatment. — 113. Honey cells. — 114. Pas- 
 turage — progress of work. — 115. Construction of comb. — 116. 
 Remarkable organisation. — 117. Magnitude and weight of bees. 
 — 118. Character of queen. — 119. Royal jealousy. — 120. Prin- 
 ciple of primogeniture. — 121. Assassination of rivals. — 122. 
 Battle of virgin queens. — 123 . Reason of mutual hostility. —124. 
 Result of the battles. — 125. Battle of married queens. — 126. 
 Battle of a virgin with a fertile queen. — 127. Sentinels at the 
 gates — Treatment of an intruding queen. — ^128. Remarkable 
 proceeding of bees that have lost their queen — effect of her 
 restoration. — 129. Efiect of the introduction of a new queen. — 
 130. Policy of the hive. — 131. Operations at the beginning of a 
 season 41) 
 
 Chap. V. — 132. Change of state of the queen after laying. — 133. 
 First swarm led by her majesty. — 134. Proceedings of the first 
 swarm. — 135. Loyalty and fidelity to the queen— remarkable 
 experiment of Dr. Warder. — 136. Interregnum after swarming. 
 — 137. The princess royal. — 138. Second swarm — its effects. — 
 139. Successive swarms. — 140. Production of a factitious queen 
 
CONTENTS. 
 
 V 
 
 — Schiracli's discovery. — 141. Factitious queens dumb. — 142. 
 Factitious princesses allowed to engage in mortal combat.' — 143. 
 Homaga only offered to a married queen. — 144. Respect sbown 
 to her corpse. — 145. Functions of the drones. — 146. Their treat- 
 ment. — 147. Their massacre described by Huber. — 148. Case 
 in which no massacre took place. — 149. Character and habits of 
 the workers. — 150. Products of their labours. — 151. Process of 
 work. — 152. Honey and pollen — nectar and ambrosia. — 153. Bee 
 the priest who celebrates the marriage of the flowers. — 154. 
 Why the bee devotes each excursion to one species of flower. — 
 155. Unloading the workers. — 156. Storage of spare provision. 
 —157. Radius of the circle of excursion , , . .65 
 
 Chap. VI. — 158. How they fly straight back to the hive. — ^manner of 
 discovering the nests of wild bees in New England. — 159. Average 
 number of daily excursions. — 160. Bee pasturage — transported 
 ^6 follow it — in Egypt and Greece. — 161. Neatness of the bee. — 
 162. Its enemies. — 163. Death's-head moth. — 164. Measures 
 of defence adopted by Huber. — 165. Measures adopted by the 
 bees. — 166. Wars between different hives. — 167. Demolition of 
 the defensive works when not needed. — 168. Senses of insects. 
 — 169. Senses of the bee. — 170. Smell. — 171. Experiments of 
 Huber. — 172. Remarkable tenacity of memory. — 173. Experi- 
 ments to ascertain the organ of smell. — 174. Repugnancy of the 
 bee for its own poison. — 175. Their method of ventilating the 
 hive. — 176. Their antipathy against certain persons. — 177. 
 Against red and black-haired persons. — 178. Difference of opi- 
 nion as to the functions of the antennae. — 179. Organs of taste. 
 — 180. Hearing : curious anecdotes. — 181. Visic^n. — 182. Pecu- 
 liar character of queens ; royal old maid. — 183. Drone-bearing 
 queens. — 184. Change of their instincts and manners. — 185. 
 Their treatment by the workers. — 186. Nuptials never celebrated 
 in the hive. — 187. Effect of amputating the royal antennae . . 81 
 
 Chap. VII. — 188. Apiculture. — 189. Suitable localities and pas- 
 turage. — 190. The Apiary. — 191. Out-door Apiary. — 192, Bee- 
 house. — 193. Cabinet bee-houses. — 194. Form and material of 
 hives. — 195. Village hive.— 196. English hive. — 197. Various 
 forms of hives.— 198. Various forms of bee-boxes. — 199. Bee- 
 dress and other accessories of apiculture. — 200. Purchase of 
 hives. — 201. Honey harvest. — 202. Honey and wax important 
 articles of commerce. — 203. Various sorts of wild honey. — 
 204. Periodical migration of bees. — 205. Poisoned honey. — 206. 
 Maladies of bees. — 207. Curious case of abortive brood. — 208. 
 Superstition of bee cultivators.— 209. Enemies of bees. — 210. 
 A^ttacks of bees when provoked. — 211. Anecdote of Mungo Park. 
 .--212. Anecdote of Thorley.— 213. Bee wars.— 214. Curious 
 case of a battle , « .97 
 
vi 
 
 CONTENTS. 
 
 STEAM NAVIGATION. 
 
 PAGE 
 
 Chap. I. — 1. Inventors of steam navigation uneducated. — 2. First 
 steamers on the Hudson and the Clyde. — 3. Sea-going steamers 
 due to British engineers, — 4. Progress of steam navigation from 
 1812 to 1837. — 5. Atlantic steamers projected. — 6. Abstract 
 possibility of the voyage could not be doubted, — 7. The voyage 
 had been already made by two steamers. — 8, Projects advanced 
 in 1836.— 9. Discussion at Bristol in 1837.— 10. Report of 
 Dr. Lardner's speech in the Times of 27th August, showing the 
 falsehood of the report that he pronounced the project imprac- 
 ticable. — 11. Atlantic steam voyage advocated by Dr. Lardner in 
 1836-7. — 12. The practical results of the various projects prove 
 the truth of his predictions. — 13. The Cunard steamers, esta- 
 blished on the conditions suggested by him, were alone successful. 
 — 14. Voyages of these steamers. — 15. Other lines established. 
 — 16. Probable extension of steam navigation to the general 
 purposes of commerce. — 17. Auxiliary steam-power the most 
 probable means of accomplishing this. — 18. Advantages of sub- 
 aqueous propulsion, — 19. Means of realising them. — 20. Im- 
 proved adaptation of steam-power to vessels of war required, — 
 21. Mercantile steam-marine available for national defence. — 22. 
 Principle of marine engine. — 23. Propellers. — 24. Paddle-wheels 
 and screws. — 25. Arrangement of paddle-wheels. — 26. Paddle- 
 shaft. — 27. General arrangement of marine engine . . .113 
 
 Chap. II, — 28. Arrangement of the engine-room ; governor and other 
 regulating parts omitted. — 29. Flue boilers and tubular boilers. 
 — 30. Construction of flue boilers. — 31. Tubular boilers, — 32. 
 Indications of engineering ignorance. — 33. Number and dimen- 
 sions of tubes. — 34. Incrustation produced by sea water. — 35. 
 Hydrometric indicators. — 37. Thermometric indicators. — 38. 
 Seaward's contrivance, — 39. Brine-pumps. — 40. Blowing out. — 
 41. To detach the scale. — 42. Effiectof corrosion. — 43. Efficiency 
 and economy of fuel. — 44. Coating the boUer and pipes with felt. 129 
 
 Chap. III. — 45. Economy of fuel. — 46. Width and depth of furnace. 
 — 47. Advantage of expansive action. — 48. Siamese engines. — 
 49. Simplified arrangements. — 50. Number and position of cylin- 
 ders. — 51. Proportion of diameter to stroke. — 52. Oscillating 
 engines.— 53. Engines of the "Peterhoff." — 54. Propellers. — 55. 
 The common paddle-wheels. — 56. Feathering paddles. — 57. 
 Morgan's paddle-wheel. — 58. Field's split paddles. — 59. American 
 paddle-wheel. — 60. Practical objections to feathering paddles. — 
 61. Proportion of marine engines. — 62. Submerged propellers. — 
 63.' Their disadvantages. — 64. Screw-propellers. — 65. Pitch and 
 slip. — 66. Manner of mounting screw-propellers. — 67. Their 
 various forms 145 
 
CONTENTS. 
 
 vil 
 
 PAGE 
 
 Chap. IV. — 68. Effect of the screw-propeller reaction on tlie vessel. 
 — 69. Their best practical proportion. — 70. Their varying pitch. 
 — 71. Relative advantages of screw and paddle-wheels. — 72. 
 Their effects in long sea-voyages. — 73. Experiments with the 
 "Rattler" and "Alecto." — 74. These experiments continued. 
 ■ — 75. Admiralty experiments. — 76. Government report. — 77. 
 Application of the screw in the commercial marine. — 78. Appli- 
 cation of screw to mail- vessels. — 79. Geared and direct action. 
 80. Geared-engines. — 81. Fairbairn's internal gearing. — 82. 
 Subdivision of the power among several cylinders. — 83. Protec- 
 tion from shot. — 84. Regulation of slides. — 85. Relative speed 
 of screw and vessel. — 86. Engines of the "Great Britain." — 87. 
 Engines of the "Arrogant" and "Encounter." — 88. Various 
 forms of sci-ew- engines. — 89. Cross action of H. M.'s screw steam- 
 packet "Plumper." — 90. Auxiliary steam-power. — 91. Effect of 
 screw-vessels head to wind. — 92. Nominal and real horse-power. 
 — 93. Official tables of the strength of the steam-navy . . 161 
 
 THUNDER AND LIGHTNING, AND THE AURORA 
 BOREALIS. 
 
 1. Atmospheric electricity. — 2. The air generally charged with 
 positive electricity. — 3. Subject to variations and exceptions. 
 — 4. Diurnal variations of electrical intensity. — Observations 
 of Quetelet. — 5. Irregular and local variations and excep- 
 tions. — 6- Variations dependent on the season and weather. — 7. 
 Methods of observing atmospheric electricity. — 8. Methods of 
 ascertaining the electrical condition of the higher strata. — 9. 
 Remarkable experiments of Romas, 1757. — 10. Electrical change 
 of clouds varies. — 11. Thunder and lightning. — 12. Form and 
 extent of the flash of lightning. — 13. Cause of the roUing of 
 thunder. — 14. Affected by the zigzag form of lightning. — 15. 
 Affected by the varying distance of different parts of the flash.-— 
 16. Affected by echo and by interference. — 17. Inductive action of 
 clouds on the earth. — 18. Formation of Fulgurites explained. — 
 19. Accidents of the surface which attract lightning. — 20. Light- 
 ning follows conductors by preference — its effects on buildings. — 
 21. Conductors or paratonnerres for the protection of buildings. 
 — 22. Effects of lightning on bodies which it strikes. — 23. The 
 Aurora Borealis — the phenomena unexplained. — 24. General 
 character of the meteor. — 25. Description of auroras seen in the 
 polar regions by M. Lottin 177 
 
 I Chap. I. — 1. Prospects of improvement in motive power by the appli- 
 cation of electricity. — 2. Example of its practical application in 
 
 . the workshop of Mons. Froment, mathematical instrument maker 
 in Paris. — 3. Mention of it in Catalogue of the Great Exhibition 
 
 ELECTRO-MOTIVE POWER. 
 
viii 
 
 CONTENTS. 
 
 in Hyde Park. — 4. Property of electro-magnets. — 5. Alternate 
 transmission and suspension of the current. — 6. How this pro- 
 duces a moving power. — 7. Voltaic piles used by Mons. Froment. 
 — 8. Forms of his electro-motive machines. — 9. Details of their 
 construction. — 10. Regulator applied to them. — 11. Their appli- 
 cation to divide the limbs of philosophical instruments. — 12. 
 Their wonderful self-acting power. — 13. Application of electro- 
 motive power to the telegraph by Mons. Froment. — 14. Micro- 
 scopic writiug. — 15. Electric clocks ..... 193 
 
rig. 5'1. — UncoTerod Apiary. 
 
 THE BEE. 
 
 ITS CHARACTETl AND MANNERS. 
 CHAPTE]^ I. 
 
 1. Moral suggested "by economy of nature. — 2. Antiquity of apiarian 
 researches — Hebrew scriptures — Aristomaclius — Piiiliscus — Aristotle 
 *— Virgil. — 3. Modern observers. — 4. Huber, — 5. His servant 
 Burnens — curious history of his blindness.— 6. His wife and son. — 
 7. Pursuit of his researches. — 8. Structure of insects. — 9. Plan of 
 their anatomy. — 10. Hymenoptera. — 11. Varieties of bees. — 12. 
 Hive bee. — 13. The queen — her numerous suitors. — 14. Her chastity 
 and fidelity. — 15. Her fertility. — 16. Her first laying. — 17. Eoyal 
 eggs.— 18. Eoyal chamber. — 19. Effect of her postponement of her 
 nuptials. — 20. The drones. — 21. The workers. — 22. Structure and 
 members of the bee. — 23. Moutb and appendages. — 24. Use of 
 proboscis. — 25. Structure of tongue. — 26. Honey-bag. — 27. Stomach. 
 —28. AntenniB.— 29. Wings.— 30. Legs.— 31. Feet.— 32. Sting.— 
 33. Organs of fecimdation and reproduction. — 34. Number of eggs 
 produced by the queen. 
 
 1. Nattjee offers herself to human contemplation under no 
 aspects so fascinating, as those in which she renders manifest the 
 provident care of the Creator for the well-being of his creatures. 
 The spectacle of infinite wisdom directing infinite power to bound- 
 
 Lardner's Museum of Science. b 1 
 
 No. 118. 
 
THE BEE. 
 
 less beneficence, never fails to excite in well- constituted minds tlie 
 most pleasurable and grateful emotions. Such, views of Nature 
 are the truest and purest fountains of that reverential love, 
 which so eminently distinguishes the Christian from all other 
 forms of worship. 
 
 In the notices from time to time given in this series of the 
 stupendous works of creation presented in the heavens, and of 
 the benevolent care displayed in the supply of the physical wants 
 of the inhabitants, not of the terrestrial globe * alone, but also of 
 the planets, t which, in company with the earth, revolve round 
 the sun, numerous examples of such beneficence are presented. 
 The vast dimensions of these works, as well as the great import- 
 ance and the countless numbers of the objects to be provided for, 
 leading the mind naturally to expect a system of provisions esta- 
 blished on a corresponding scale, their display, while it excites 
 equal admiration and reverence, produces a less intense sentiment 
 of wonder. When, however, we turn our view from the vast 
 works of creation exhibited in the celestial regions, to the more 
 minute ones presented in the organised world around us, our 
 wonder is as much excited as our admiration, at beholding the 
 same traces of Divine care in the economy of an insect, as were 
 observed in the structure and motions of a planet. There are the 
 same infinite wisdom and foresight, the same unapproachable 
 skill, the same boundless goodness directed to the maintenance of 
 the species and the well-being of the individual, as we have seen 
 displayed in the provisions for a globe a thousand times larger 
 than the earth, or for a cluster of worlds millions of times more 
 numerous than the entire solar system, sun, earth, planets, moons, 
 and all ! We have thus before us a demonstration that as the 
 most stupendous works of the universe — the expression of whose 
 dimensions surpasses the powers of arithmetic — are not above 
 Divine control and superintendence, so neither are the most insig- 
 nificant of creatures — whose existence and structure can be made 
 evident only by the microscope — below the same benevolent care. 
 
 2. Among the numerous examples, suggestive of reflections 
 such as these, presented by the insect-world, there is none more 
 remarkable than the little creature, to the character and economy 
 of which we shall devote this notice. How true this is, is proved 
 by the examples of those who, in all ages of the world, have de- 
 voted their labours to the observation and investigation of its. 
 character and habits. In the Hebrew Scriptures numerous allu- 
 sions to the bee show that, in those remote times, it had already 
 
 * See Tracts on the Earth, Geography, Terrestrial Heat, Air, Water, &c. 
 + See the Planets, are they inhabited ? the Sun, the Moon, the Stellar. 
 Universe, &c. 
 2 
 
ARISTOTLE VIRGIL — HUBER. 
 
 been a subject of attention witb the wisest and the best. Pliny 
 relates that Aristomachus of Soli in Cilicia devoted fifty- eight 
 years of his life to the study of the bee ; and that Philiscus, the 
 Thracian, passed so large a part of his time in the woods observing 
 its habits, that he acquired the title of Agrius. Among his 
 numerous researches in natural history, Aristotle assigned a con- 
 siderable share to the bee ; and Yirgil devoted to it the fourth 
 book of his Georgics : — 
 
 *' Protenus aerii mellis ccelestia dona 
 Exsequar. Hanc etiam, Maecenas, adspice partem. 
 
 - Admiranda tibi levium spectacula rerum, 
 Magnanimosque duces, totiusque ordine ^'entis 
 Mores, et studia, et populos, et praelia dicam. 
 In tenui labor ; at tenuis non gloria, si quem 
 Kumina laeva sinunt, auditque vocatus Apollo." 
 
 Georg. IV. 1—7. 
 
 * ' The gifts of Heaven my following song pursues. 
 Aerial honey, and ambrosial dews. 
 Maecenas, read this other part that sings 
 Embattled squadrons and advent'rous kings — 
 Their arms, their arts, their manners, I disclose. 
 And how they war and whence the people rose. 
 Slight is the subject, but the praise not small 
 If Heaven assist, and Phcehus hear my call." 
 
 Drydeit. 
 
 3. In modern times the bee has been the subject of the obser- 
 vations and researches of some of the most eminent naturalists, 
 among whom may be mentioned Swammerdam (1670), Maraldi 
 (1712), Eay, Reaumur (1740), Linnseus, Bennet, Schirach, John 
 Hunter, Huber — father and son, — and more recently Kirby, whose 
 monograph upon the English bees may be regarded as a classic in 
 natural history. 
 
 4. Among these, the elder Huber stands pre-eminent, not only 
 for the extent and importance of his contributions to the history of 
 the insect, but for the remarkable circumstances and diflficulties 
 under which his researches were prosecuted. Visited with the 
 privation of sight at the early age of seventeen, his observations 
 were made with the eyes and his experiments performed with the 
 hands of others ; and, notwithstanding this discouragement and 
 obstacles which might well have been regarded as insurmountable, 
 he continued his labours for forty years, dui'ing which he made 
 those discoveries which have conferred upon him such celebrity. 
 
 5. Happily for science, Huber, after losing his sight and at the 
 commencement of his researches, had in his service a domestic, 
 named FraD9ois Burnens, a native of the Pays de Vaud, in Swit- 
 zerland. Eeading and writing constituted the extent of the 
 
 B 2 3 
 
THE BEE. 
 
 education of this person ; but nature had bestowed upon him 
 faculties which, with better opportunities, would have rendered 
 him an eminent naturalist. Huber commenced by employing him 
 as a reader. 
 
 He read to his master various works on physics, and, among 
 others, those of Reaumur, in which the admirable observations of 
 that naturalist on the bee are so clearly and beautifully stated. 
 Huber soon perceived by the observations and reflections of his 
 reader, and by the consequences he deduced from what he read, 
 that he had at his disposition no ordinary person, and resolved to 
 profit by him. He accordingly procured the means of prosecut- 
 ing a series of observations on the economy of the bee, with the 
 aid of "the eyes, the hands, and the intelligence of Burnens. All 
 the observations of Reaumur were first repeated, and the accord- 
 ance of the phenomena, as described by Burnens, with those 
 which had been recorded by Reaumur, gave Huber full confi- 
 dence ; and the master and servant, quitting the beaten path, 
 entered upon new ground, and during a period of fifteen years, 
 prosecuted those researches in the natural history and economy of 
 the bee, which, being committed to writing by the hand of Bur- 
 nens at the dictation of Huber, were published in one volume 
 about 1792, in form of letters addressed by Huber to Bonnet. 
 
 6. Soon after this, Huber lost his invaluable colleague, for 
 servant he had long ceased to be. Burnens was recalled by 
 family ties to his native place, where the personal estimation in 
 which he was held caused him to be raised to a high position in 
 the local magistracy. 
 
 Previously to this, Huber had the good fortune to consolidate his 
 domestic happiness by marriage. * ' My separation from my faithful 
 and zealous Burnens," said Huber, " which was not the least cruel 
 of the misfortunes with which I was visited, was, however, softened 
 by the satisfaction which I felt in observing JSlature through the eyes 
 of the being who was dearest to me, and with whom I could com- 
 mune with pleasure on the most elevated topics. But what more 
 than all the rest contributed to attach me to natural history, was 
 the taste manifested by my son for that subject. I explained to 
 him the results of my observations and researches. He expressed 
 the regret he felt that labours which would, as it seemed to him, 
 so deeply interest naturalists should remain buried in my port- 
 folio. Perceiving, meanwhUe, the secret repugnance that I felt 
 against the task of reducing them to order, he proposed to take 
 charge of that labour." 
 
 7. From that time our great naturalist was again consoled, by 
 having at his disposal two pair of eyes in place of one. The wife 
 and the son, animated by a common enthusiasm, and urged by 
 
 4 
 
STRUCTURE OF INSECTS. 
 
 conjugal and filial devotion, more than compensated for the loss 
 of Burnens ; and the observations and researches were pursued 
 with unabated zeal, and were finally collected and published in 
 the second volume, which appeared about 1814, more than twenty- 
 years after the publication of the first.* 
 
 8. Since any explanation, however popular and familiar, of the 
 economy and habits of the bee, must necessarily involve very 
 frequent references to its structure and organs, it will be con- 
 venient in the first instance briefly to explain the terms, by which 
 naturalists have designated its several parts. 
 
 The body of insects in general consists of a series of annular 
 segments, so articulated one to another as to allow more or less 
 flexibility. It consists of three chief parts, the head, the thorax, 
 and the abdomen. 
 
 The head consists of a simple segment, the thorax of three, and 
 the abdomen of a greater number, sometimes as many as nine. 
 Each segment is distinguished by its ventral or inferior, and 
 dorsal or superior part. 
 
 Insects have three pairs of legs, which are inserted in the sides 
 of the ventral parts of the three thoracic segments of the body ; 
 and generally two pairs of wings, which are inserted in the sides 
 of the dorsal parts of the second and third thoracic segments, 
 counting from the anterior to the posterior part of the body. 
 
 A pair of members, called antennce, are inserted in the sides of 
 the head, varying much in structure in different classes, and 
 in many, including the bee, have the form of slender and flexible 
 horns, consisting of many minute pieces articulated one to another. 
 These are generally presumed to be tactile organs, and are con- 
 sequently sometimes caHed feelers. 
 
 9. This description will be more easily comprehended by 
 reference to the annexed diagram, fig. 1, which may be taken 
 as a general theoretical representation of the structure of an 
 insect. 
 
 As here indicated, the three thoracic segments are distinguished 
 as the pro-, meso-, and metathorax. 
 
 10. Insects have been classified by naturalists according to the 
 structure of their wings, and the order to which the bee has been 
 assigned, and of which it is regarded as the type, is the Hymen- 
 optera, a compound of two Greek words signifying membranaceous 
 wings. 
 
 The section or subsection of the order of Hymenoptera, which 
 in its economy and peculiar construction differs most from all 
 other orders of insects, has been designated by Latreille MeUifera, 
 
 * " Kouvelles Observations sur les Abeilles." Paris, 1814. 
 
THE BEE. 
 
 a Latin word signifying Hotkey- G4.therees ; or Anthophila, a 
 Greek word signifying Flower-Lovees. 
 
 Fig. 1. 
 
 11. How numerous are tlie varieties of bees may be conceived, 
 when it is stated that of bees found in Great Britain alone, Kirby 
 in his Monograph has enumerated 220 species, and other more 
 recent observers have increased the number to 250. The species, 
 however, which by its commercial importance, as well as by its 
 remarkable habits and social organisation, presents the greatest 
 interest, is the Hive Bee, to which, therefore, we shall chiefly 
 limit our notice. 
 
 12. The Hive bee belongs to what naturalists have denominated 
 the perfect societies of insects. Each community of these insects 
 consists of three orders of individuals distinguished by their 
 number, their organisation, and the respective share they take in 
 the common labour of the society. These are denominated seve- 
 rally the queen or sovereign, the males or drones, and the workers; 
 the latter consisting of two classes, called the wax- makers and 
 the nurses. A hive which contains as many as 50000 bees will 
 have only one queen, and not above 2000 males. 
 
 13. The queen who, as her title implies, is the acknowledged 
 6 
 
QUEEN — DRONES — WORKERS. 
 
 monarch of the hive, is distinguished from her subjects by con- 
 spicuous personal peculiarities. Her body, fig. 2, is considerably 
 
 Fig. 2. Fig. 3. Fig. 4. 
 
 Nurse, loaded witli pollen. Drowe in flight, showing 
 
 organs of fecundation. 
 
 longer than that of any of her subjects; she is distinguished by a 
 more measured and majestic gait, by the comparative shortness of 
 her wings, and the curvature of her sting. Her wings, which are 
 strong and sinewy, are only half the length of her body, extending 
 very little beyond the posterior limit of her thorax, while those of 
 the drones, fig. 3, and the workers, fig. 4, cover the abdomen. Her 
 legs are destitute of the brushes and baskets with which those of 
 the workers are furnished. She has no occasion for these instru- 
 ments of industry, since her exalted station exempts her from 
 labour, all her wants being munificently provided for by her 
 subjects. She is distinguished by her colour as much as by her 
 form, the black of the dorsal part of her body being much brighter 
 than that of the drones and workers, and the ventral parts and 
 legs being of dark orange or copper-colour, the hue of the hinder 
 being deeper than that of the other legs. 
 
 The queen, who is the only lady of the hive, enjoys the 
 privilege of being followed by many hundred suitors in the persons 
 of the drones. At the early age of two or three days she is mar- 
 riageable, and it rarely happens that her royal decision is long 
 postponed ; and, indeed, if she were not favourably disposed for 
 such an event, the anxiety of her numerous subjects would urgG 
 
THE BEE. 
 
 her to it, for in no human monarchy are the hopes of succession so 
 anxiously cherished as in the Empire of the Hive. 
 
 14. It must not be imagined, that because a lady is thus 
 domesticated alone with so many hundred lovers, there is any 
 the least degree of laxity in the morals of the society ; on the con- 
 trary, although she is absolutely uncontrolled, and is courted 
 by so many hundreds, her choice is strictly limited to one. A fine 
 warm sunny day is selected for the nuptials, which are celebrated 
 in the air. On the auspicious occasion, her majesty issuing from 
 the hive followed by the multitude of her suitors, rises in the air, 
 where she is encircled by the flight of the candidates for her 
 favour. Here she makes her selection, but, alas! the felicity is 
 brief, for the object of her choice never outlives the wedding-day. 
 She is, however, not the less faithful to him, and never contracts 
 a second marriage. 
 
 15. Though her majesty is thus left a widowed bride, in 
 two days after the celebration of her nuptials and the loss of 
 her lord, she commences to lay eggs from which a posthumous 
 progeny of that lord, countless in number, are destined to issue. 
 Of the hundreds of rejected suitors, a limited number emigrate 
 with the successive swarms, which from time to time leave the 
 overpeopled hive. Those which remain, being no longer useful to 
 the community, become objects of general aversion, and are finally 
 exterminated by a general massacre, as will presently be more 
 fully explained. 
 
 16. During six or eight weeks the queen constantly lays eggs, 
 from which working bees only are destined to issue. Chambers 
 have been previously prepared for these, suitable to the future 
 young ones, in form, size, and position, by the workers. In each 
 of those cells the queen deposits a single egg. 
 
 At a later period her majesty begins to lay another kind of egg, 
 from which males will issue. For these also special chambers 
 have been provided by the careful workers, of suitable dimen- 
 sions, being somewhat more roomy than those prepared for 
 worker-eggs. The number of these male eggs and of the 
 cells for their reception is incomparably less than those of the 
 workers ; less, in short, in the proportion in which the drone 
 class is less numerous than that of the workers in the population 
 of the hive. 
 
 17. In fine, the queen, sensible of her mortality, and more- 
 over of the approaching state of superabundant population in the 
 hive, lays a certain small number of royal eggs, from which as 
 many princesses issue, who are severally destined to be candidates 
 for the thrones of the colonies which are to emigrate, or to succeed 
 to the throne of the hive itself, should the queen-mother, as often 
 
 8 
 
ROYAL NUPTIALS. 
 
 happens, decide on abdicating and accepting the allegiance of one 
 or other of the emigrating colonies. 
 
 18. Special chambers of exceptional form, position and magni- 
 tude have been previously prepared for these royal eggs by the 
 provident workers. In these the princesses are reared and 
 educated with extraordinary care, being fed with a peculiar food. 
 
 19. It is essential to the prosperity of the community, that the 
 nuptials of the queen should not be postponed to a later period 
 than the second day of her age, the consequence of such postpone- 
 ment being that her progeny would consist of a redundancy of 
 drones. Thus, if the marriage be postponed till she is about a 
 fortnight old, she will lay as many drone as worker-eggs, and if 
 it be delayed until her age is three weeks, she will only lay 
 drone eggs. How great a calamity such events must be in the 
 apiarian economy will be understood, when it is considered that 
 in a well-regulated society there ought to be about ten workers 
 to each drone. The general duration of the life of a queen is 
 from five to six years. 
 
 20. The males or drones, fig. 3, are less than the queen and 
 larger than the workers, fig. 4. The extremity of the body is 
 more velvety. The last segment being fringed with hair, extend- 
 ing over the tail, so as to be visible to the naked eye. They take 
 no part whatever in the labours of the community, contribute 
 nothing to the common stock, are idle, slothful, and cowardly, and, 
 as if to render their extermination more easy to the industrious 
 part of the population, nature has given them no sting. They make 
 a louder buzz with their wings in flight, never exercise any in- 
 dustry, and are destitute of the baskets and other appendages with 
 which the busy workers collect the materials of honey and wax. 
 
 The life of a drone does not exceed a few months, and he 
 seldom dies a natural death. If he is honoured by the choice of 
 the queen and elevated to the rank of king- consort, he dies on 
 the very day of the nuptials. If he be among the hundreds 
 rejected by her majesty, and do not emigrate with one or other 
 of the swarms, being a useless and idle member of the community, 
 he is massacred by the workers. 
 
 21. The workers, sometimes called neuters, are generally con- 
 sidered as sterile females. The number of these in each com- 
 munity is very variable, being seldom less than 12000, more 
 generally amounting to 20000, and in hives where swarming is 
 checked by affording abundance of room, the number may rise to 
 60000. They are the smallest members of the society, fig. 4, 
 have a long flexible proboscis and legs of peculiar structure. 
 
 22. Among the wonders presented by the insect- world the head 
 of the bee and its appendages command especial attention. 
 
THE BEE. 
 
 In common with insects generally, the chief parts of the mouth 
 are, the tongue , Mh^jaws, the lips, and the throat or oesophagus. 
 
 The jaws are each double, separated by a vertical division. 
 Each pair opens, therefore, with a horizontal instead of a vertical 
 movement like the human jaws. The pair of upper jaws are called 
 mandibles, and the lower maxilla. The upper lip is called the 
 lahrum and the lower the labium. The mouth is also supplied 
 with two pairs of special organs called palpi or feelers, one pair 
 attached to the lower lip and called labipalpi, and the other to the 
 lower jaw and called inaxipalpi. 
 
 23. In fig. 7, is given a magnified view of the buccal apparatus 
 of the wild bee {Anthophora retusa)* the parts being indicated. 
 
 F^-v T. 
 
 A less detailed view, also magnifiid, of the same apparat is of 
 the hive-bee is shown in fig. 8. 
 
 Mandibles . . . \ 4 J 1 • - • Mandibles 
 
 Latei-al sheath. 
 
 Inner sheath. 
 
 . . Lateral sheath 
 
 . . Inner sheath 
 
 10 
 
 . . . Tongue 
 Fig. 8. — Tongue of Hive bee (magnified). 
 * Milne Edwards. 
 
HEAD, AND MOUTH. 
 
 A magnified view of the Lead of tlie drone is shown in fl^-. 9. 
 
 AutennEe 
 
 Compound eyes , . J^^iMin^^^ • • Compound eyes 
 
 Mandibles . . . Vf/ • • • Mandibles 
 . . . Tongue 
 Fig. 9. — Head of a Drone (magnified). 
 
 The mandibles, or upper pair of jaws, in the workers are strong, 
 horny and sharp. They are the tools with which it performs its 
 various labours. Meeting over the other parts of the mouth, they 
 are covered in front by the labrum or upper lip. The maxillae, or 
 lower jaws, on the contrary are pliable and leathery, and hold the 
 objects upon which the insect works with its mandibles. 
 
 The tongue, which is long and endowed with great flexibility, 
 is moved by a complex system of powerful muscles. When it is 
 in a state of inaction, it is withdrawn within its sheaths, the 
 end which protrudes beyond them being doubled up under the 
 head and neck, the sheaths consisting of two pair of strong 
 scales. 
 
 24. "When the bee lights upon the blossom of a flower from 
 which it desires to extract the nectar, it darts out its tongue from 
 the sheaths that invest it, and having 
 pierced the petals and stamina where 
 the treasure is hidden, it inserts its 
 tongue which moves about in every 
 direction in virtue of its great flexibility 
 and muscular power, and probes to the 
 very bottom the floral cells, sweeping 
 their surfaces and draining them to the 
 last drop of their precious juice. Having pig. lo.-Worker extracting 
 
 thus collected the nectar upon the nectar from a blossom. 
 
 tongue, that organ being drawn back 
 
 into the mouth, the liquid sweets are projected back into the 
 pharynx, and thence into the throat or oesophagus. 
 
 25. It must be observed also, that the tongue is not only flexible 
 but sugceptible of inflation, so as to form a sort of bag,* in which 
 
 * Dr. Bevan on the Honey Bee, p. 298. 
 
 11 
 
THE BEE. 
 
 Ihe nectar is collected preparatory to being transferred to the 
 oesophagus. 
 
 26. The first stomach or honey-bag into which the nectar 
 
 stomach. 
 
 Fig. 11.— Digestive apparuLuo of tlie JBee (magnified). 
 
 passes through the oesophagus, — which is a long and slender tube 
 passing from the back of the mouth through the neck, — has the 
 form of a Florence flask, and is composed of a material as trans- 
 parent as glass. When filled it has the magnitude of a small pea. 
 The honey received by it is partly regurgitated and deposited for 
 general use in the cells of the comb, which will presently be 
 described. The remainder which constitutes the food of the insect 
 passes into the true stomach, and from thence into the intestines 
 where it undergoes the process of digestion, the products of which 
 are distributed through suitable tubes to all parts of the body for 
 its nourishment. 
 
 27. Both the honey-bag and the stomach, are susceptible of 
 contraction, by which the food is thrown back from the former 
 into the mouth as in ruminating animals, and from the latter into 
 the intestines. 
 
 28. The antennae are organs of great importance, upon the 
 functions of which, however, naturalists are not fully agreed. It 
 appears certain nevertheless, that they are not only tactile instru- 
 ments of great sensitiveness, but are organs, by the signs, gestures, 
 and mutual contact of which the bees communicate to each other 
 their mutual wants, and convey information in many cases, some 
 of which will be noticed hereafter, respecting the condition of the 
 hive. 
 
 29. The flying-apparatus of the bee, as well as that of many 
 other insects, far exceeds in power the instruments of flight with 
 which the swiftest birds are furnished. To the anterior margin 
 of the under wings are attached eighteen or twenty hooks, which 
 when spread for flight (figs. 5, 6) lay hold of the posterior edges 
 of the upper wings, so that the two wings on each side thus united 
 act as a single wing. 
 
 12 
 
LEGS. 
 
 30. The three pairs of legs are composed of several joints (fig. 1) 
 articulated like those of the human arm, so as to give great 
 mobility to the member. The lower joints of the two under pairs 
 form brushes, the hairs of which are stiff and bristly, and set 
 upon their inner surfaces. The farina which they collect from 
 the stamina of flowers is swept off by these brushes, as well as by 
 the hairs with which their abdomen and thorax are covered. This 
 farina is afterwards by means of the maxillae or jaws, and the feet 
 of the anterior pair of legs, rolled into pellets and packed in a pair 
 of spoon-shaped cavities or baskets, provided for that purpose and 
 attached to the feet of the hindmost pair of legs. In this process 
 the brushes, after disposing of their own collection of farina, 
 sweep that flour also from the surface of the abdomen and thorax, 
 and pack it in like manner in the baskets. The exterior of these 
 baskets is smooth and glossy, and the interior lined with strong 
 close hairs to retain the load in its place, and prevent its escape 
 in flight. 
 
 Fig. 12. — Posterior leg of a worker. 
 
 It is worthy of remark that neither the queen nor the drones 
 are supplied with this appendage. Since neither exercise any 
 industry they would have no use for it. 
 
 31. Each foot terminates in two hooks, the points of which are 
 opposed one to the other. By means of these the insects suspend 
 themselves at will to the sides and roofs of their habitation, and 
 hanging from each other form a living curtain in certain operations 
 which will be presently noticed. 
 
 In the middle of each of these is placed the sticker, by which 
 the insect is enabled to walk with facility on surfaces with its body 
 downwards, as we see flies walk on ceilings. These suckers are 
 little flexible cups, the edges of which are serrated so as to allow 
 of their close application to any kind of surfa ce. tVhen closely 
 applied, the air between the sucker and the surface is excluded, 
 so that the body is attached to the surface by the pressure of the 
 atmosphere. When the foot is to be detached from the surface, 
 as in walking, the air is readmitted. This apparatus may be 
 
 13 
 
THE BEE. 
 
 easily seen, and its action observed, by inspecting witb a microscope 
 the feet of a fly walking on a pane of glass, tbe observer being on 
 the side of the pane opposite to that on which the fly moves. 
 
 32. Besides the stomach and intestines, the abdomen of the 
 queen and workers contains the sting and the apparatus connected 
 with it, by which the venom which it pours into the wound is 
 secreted, an instrument of offence supplied to these in common 
 with many other species of four- winged insects. This formidable 
 weapon of vengeance is established in its tail. All the insects 
 which in common with the bee are supplied with a sting, belong 
 to tlie order hymenoptera or membrane-winged. This weapon 
 consists of two darts finer than a hair, which lie in juxta- 
 position, being barbed on the outer sides, but so minutely that 
 the points can only be seen with the microscope. These darts 
 move in the groove of a strong sheath, which is often mistaken 
 for the sting itself. When the dart enters the flesh, a drop of 
 subtle venom, secreted by a peculiar gland, is ejected through 
 the sheath and deposited in the wound. This poison produces 
 considerable tumefaction, attended with very acute pain. 
 
 The posterior extremity of the body of a worker with the sting 
 prctruded is shown in fig. 13, 
 
 Fig. 14. — The same sliglitly magnified, showing 
 the veuom-bag. 
 
 The sheath of the sting, also called the ovipositor, consists, ac- 
 cording to Dr. Bevan, of a long tube, or rather of several tubes, 
 wliich pass one into another like those of a telescope. The muscles 
 by which the sting is propelled, though too minute to be seen 
 without the microscope, have, nevertheless, sufficient power to 
 drive the sting to the depth of the twelfth of an inch into the thick 
 cuticle of a man's hand. The sting is articulated by thirteen scales 
 to the posterior extremity of the body, and at its root are the pair 
 of gland?, one of which appears in fig. 14, in which the poison 
 U 
 
STING. 
 
 is secreted. These glands, communicating by a common duct with 
 the groove formed by the junction of the lower parts of the barbed 
 sting, send the venomous liquid through that groove into the 
 wound. On each dart there are four barbs. When the insect 
 intends to sting, one of these piercers having its point a little 
 longer, or more in advance than the others, is first darted into the 
 flesh, and being fixed there by its barb, the other strikes in also ; 
 and they alternately penetrate deeper and deeper, till they acquire 
 a firm hold of the flesh with the barbed hooks, and then follows 
 the sheath, enclosing and conveying the poison into the wound. 
 The action of the sting thus, as Paley observed, affords an example 
 of the union of chemical and mechanical principles : of chemistry, 
 in respect to the venom ; and of mechanism, in the motion into 
 the flesh. The machinery would have been comparatively useless, 
 had it not been for the chemical process by which in the body of 
 the insect honey is converted into poison ; and, on the other hand, 
 the poison would have been ineffectual without an instrument ta 
 wound, and a syringe to inject it. 
 
 In consequence of the barbed form of the sting, and the strong, 
 hold it takes on the flesh, the bee can seldom withdraw it, and in- 
 detaching herself from the part stung she generally leaves behind 
 her not only the sting itself, but the venom-bag and a part of her 
 intestines. Swammerdam mentions a case in which even the 
 stomach of the insect was torn from the abdomen in detaching 
 herself, so that in most cases her life is the sacrifice for the grati- 
 fication of her vengeance. 
 
 Although the bee, except in certain cases to be mentioned, 
 hereafter, uses its sting only in defence, or for vengeance, when 
 molested, it is sometimes found that it manifests an antipathy ta 
 pnrticular individuals, whom it attacks and wounds without pro- 
 vocation. 
 
 33. The organs of fecundation and reproduction are also con- 
 tained in the abdomen. Those of the drone are represented on a. 
 magnified scale in fig. 15. They correspond in their functions to 
 those of the superior animals. 
 
 Fig. 15.— Apparatus of fecundation of the drone. 
 
 The organs of reproduction of the queen, which are objects of 
 considerable interest, are shown on a magnified scale in fig. 16. 
 
 16 
 
THE BEE. 
 
 34. "We have already stated that the king-consort never sur- 
 vives the bridal day. As this does not affect the conjugal fidelity 
 
 Fig. IG.— Ovaries of the quceu and tlieir appendages. 
 
 of her majesty, who never allows a successor to her departed 
 lord, so neither does it impose any limit to the posthumous off- 
 spring which she bears to him. Small as are the ovaries, or egg 
 organs, which are shown highly magnified in fig. 16, her majesty, 
 according to Huher, generally produces from them about 12000 
 eggs in the short interval of two months, being at the average 
 rate of 200 per day. 
 
 Although her majesty does not continue so prolific during the 
 remainder of her life, she nevertheless gives birth to a progeny 
 enormous in number. The number of eggs deposited by her in 
 the cells in the months of April and May is, as above stated, about 
 12000. According to Schirach, a prolific queen will lay in a 
 season — that is, from April to October inclusive — from 70000 to 
 100000 eggs. This amazing power of reproduction is not exerted 
 uniformly during the season. There are two fits, so to speak, of 
 fruitfulness. The first in April and May ; the second, in August 
 and September, with an interval of comparative repose in July. 
 This imniense increase of population, rendering emigration indis- 
 pensable, the over-peopled hive sends forth swarm after swarm 
 so fast as the young arrive at maturity ; and with each swarm 
 one of the princesses goes forth, and is elevated to the throne of 
 the new colony, except in the event of the abdication of the queen- 
 mother, in which case she emigrates herself, resigning the sove- 
 reignty of the hive to one or other of the princesses. 
 
 16 
 
Fig. 76.— Hiving a swarm. 
 
 THE BEE. 
 
 ITS CHARACTEE AND MANNERS. 
 
 CHAPTEE II. 
 
 So. This fecundity not anomalous. — 36. Bee architecture. — 37. Social 
 condition of a people indicated by their buildings. — 38. This test 
 applied to the bee. — 39. Individiial and collective habits. — 40. 
 Solitary bees. — 41. Structure of their nests. — 42. Situation of nests. 
 — 43. Anthidium manicatum. — 44. Expedient for keeping nest 
 warm. — 45. Clothier bee. — 46. Carpenter bee. — 47. Mason bee. — 48. 
 Expedient to protect the nest. — 49. Upholsterer bee. — 50. Hang- 
 ings and carpets of her rooms. — 51. Leaf-cutter bees. — 52. Method 
 of making their nest. — 53. Process of cutting the leaves. — 54. Hive- 
 bee. — 55. Structure of the comb. — 56. Double layer of cells. — 57. 
 Pyramidal bases. — 58. Illustrative figures. — 59. Single cells. — 60. 
 Combination of cells. — 61. Great advantages of hexagonal form. — 62. 
 Economy of space and material. — 63. Solidity of structure. — 64. Gfeome- 
 trical problem of the comb solved. — 65. Expedient to secure the sides 
 and bases of the cells. 
 
 35. The prodigious fecundity of the queen of the hees is by no 
 means an anomaly in the insect world. The female of the white 
 ants produces eggs at the rate of one per second, or 3600 per hour, 
 or 86400 per day. Now, although this insect certainly does not 
 
 Laedker's Museum of Science. o 17 
 
 No. 119. 
 
THE BEE. 
 
 lay at this rate all the year round, yet, taking the lowest estimate 
 of the period of her reproduction, the number of her young will 
 probably exceed not only that of the queen bee, but that of any 
 other known animal.* 
 
 36. There is nothing in the economy of the bee more truly 
 wonderful, nor more calculated to excite our profound veneration 
 of the beneficent power, which conferred upon it the faculties- 
 which guide its conduct, than the measures which it takes for the 
 construction of its dwelling, and for those of its young. These 
 processes are very various, according to the particular species of 
 the insect which executes them. Now, most of these species 
 
 ' diiFer in the mechanical and architectural principles upon which 
 they base the construction of their dwellings, all agreeing, never- 
 theless, in this, that they select those principles with admirable 
 skill, adapting them in all cases to the situation and circum- 
 stances in which their habitations are erected. 
 
 37. If we would form an estimate of the civilisation and intel- 
 ''ectual condition of the population of a newly-discovered country, 
 we usually direct our attention, as Kirby observes, to their build- 
 ings and other examples of architectural skill. If we find them 
 like the wretched inhabitants of Van Diemen's land, without 
 other abodes than natural caverns, or miserable penthouses of 
 bark, we at once regard them as ignorant and unhumanised. If, 
 like the South Sea islanders, they live in houses of timber 
 thatched with leaves, and supplied with various utensils, we 
 place them much higher in the scale. But when we discover a 
 nation inhabiting towns like the ancient Mexicans, consisting of 
 stone houses regularly arranged in streets, we do not hesitate to 
 pronounce them advanced to a considerable point in civilisation. 
 
 If, moreover, it be found that each building has been con- 
 structed upon the most profound mathematical principles, so that 
 the materials have been applied under such conditions as ensure 
 the greatest degree of strength, combined with the greatest degree 
 of lightness ; and that, while the internal apartments display the 
 most beautiful symmetry, they also aflbrd the greatest capacity 
 which a given amount of materials can admit, we at once arrive 
 at the conclusion that such a population must have arrived not 
 alone at the highest degree of civilisation, but at the highest point 
 in the advancement of the sciences. 
 
 38. If we were to affirm that all this may be said with the 
 most rigorous truth of many varieties of the bee, and above all of 
 the common hive-bee, we might be suspected of being merely 
 excited by that enthusiasm so common with those, who devote 
 
 18 
 
 * See Tract on the White Ants. 
 
KESTS. 
 
 themselves exclusively to one particular pursuit. We must, 
 nevertheless, leave the reader to judge how far such a statement 
 is chargeable with the exaggeration of enthusiasm, when he shall 
 have duly pondered upon all that we shall explain to him in the 
 following pages ; and if, perchance, his wonder he raised to the 
 point of incredulity, that sentiment wiU he repressed when he 
 remembers, who taught the bee ! 
 
 39. Bees, like the human race, sometimes exercise their industry 
 individually and sometimes collectively. Their habitations also are 
 sometimes constructed exclusively for their young, and may be 
 called nests rather than dwellings. This is more especially the case 
 with solitary insects. In the case of social bees, which live together 
 in organised communities, the habitations are generally adapted as 
 well for the members of the colony themselves, as for their progeny. 
 
 40. The operations of these soHtary insects, though exhibiting, 
 as will presently appear, marvellous skiU, are infinitely inferior to 
 those of the social bees. "We shall, therefore, first notice the 
 more simple labours of the former. 
 
 41. Among the most inartificial structures executed by the 
 solitary species, are the habitations of the colletes succinctcSj 
 fodienSf &c. The situation chosen in these cases is either a bank 
 of dry earth, or the cavities of mud walls. A cylindrical hole 
 pierced in a horizontal direction about two inches in length is 
 first produced. The bee makes in this three or four thimble- 
 shaped cells, each of which is about a sixth of an inch in diameter 
 and half an inch long, fitting one into another like thimbles. The 
 materials of these cells is a silky membrane resembling gold- 
 beater's leaf, but much finer, and so very thin and transparent 
 that the form and colour of any enclosed object can be seen 
 through it. This material is secreted by the insect. When the 
 first of these cells is completed, the insect deposits in it an egg and 
 fills it with a pasty substance, which is a mixture of pollen and 
 honey. When this is done she proceeds to form the second cell, 
 inserting its end in the mouth of the first as above described, and 
 in like manner lays an egg in it and deposits with it a like store 
 of food for the future young. This goes on until the cylindrical 
 hole receives three or four cells which nearly fill it. The bee 
 then carefully stops up the mouth of the hole with earth. 
 
 42. The situations in which these simple nests are placed are 
 very various. They are not only found as above stated in banks 
 of earth and mud walls, and the interstices of stone walls, but 
 often also in the branches of trees. Thus a series of them was 
 found by Grew in the pith of an old elder branch. 
 
 43. Some varieties of the bee, such as the anthidium manicatumy 
 dispense with the labour of boring the cylindrical holes above 
 
 c 2 19 
 
THE BEE. 
 
 described, and avail themselves of the ready-made cavities of trees, 
 or any other object which answers their purpose. Kirby mentions 
 the example of nests of this kind found by himself and others, 
 constructed in the inside of the lock of a garden-gate. 
 
 44. A proceeding has been ascertained on the part of these 
 insects in such cases, which it is extremely difficult to ascribe to 
 mere instinct, independent of some intelligence. Wherever the 
 nest may be constructed, the due preservation of the young requires 
 that until they attain the perfect state, their temperature should 
 be maintained at a certain point. So long as the material sur- 
 rounding their nest is a very imperfect conductor of heat, as 
 earth or the pith of wood is, the heat developed by the insect, 
 being confined, is sufficient to maintain its temperature at the 
 requisite point. But if, perchance, the mother-bee select for her 
 nest any such locality as that of the lock of a gate, the metal, 
 being a good conductor of heat, would speedily dissipate the animal 
 heat developed by the insect, and thus reduce its temperature to 
 a point incompatible with the continuance of its existence. How 
 then does the tender mother, foreseeing this, and consequently 
 informed by some power of the physical quality peculiar to the 
 metal surrounding the nest, provide against it ? How, we may 
 ask, would a scientific human architect prevent such an even- 
 tuality ? He would seek for a suitable material which is a non- 
 conductor of heat and would surround the nest with it. In fact 
 the very thing has occurred in a like case in relation to steam- 
 engine boilers. The economy of fuel there rendered it quite as 
 necessary to confine the heat developed in the furnace, as it is to 
 confine that which is developed in the natural economy of the 
 pupa of the bee. The expedient therefore resorted to is to invest 
 the boiler in a thick coating of a sort of felt, made for the pur- 
 pose, which is almost a non-conductor of heat. A casing of 
 sawdust is also used in Cornwall for a like purpose. By these 
 expedients the escape of heat from the external surface of the 
 boiler is prevented. 
 
 45. The bee keeps its pupa warm by an expedient so exactly 
 similar, that we must suppose that she has been guided either by 
 her own knowledge, or by a power that commands all knowledge, in 
 her operations. She seeks certain woolly leaved plants, such as the 
 stachys lanata or the agrostemma coronaria, and with her 
 mandibles scrapes off the wool. She rolls this into little balls, 
 and carrying it to the nest, sticks it on the external surface by 
 means of a plaster, composed of honey and pollen, with which 
 she previously coats it. Thus invested, the cells become impervious 
 to heat, and consequently all the heat developed by the little 
 animal is confined within them. 
 
 20 
 
CLOTHIEKS — CARPENTEES — MASONS. 
 
 This curious habit of swathing up its pupa in a kind of warm 
 blanket has given to these species the name of clothiers. 
 
 46. Another class of bees has acquired the name of carpenters, 
 from the manner in which they carve out their nest in wood- 
 work. This bee, which is represented in fig. 17, and of which 
 the nest is shown in fig. 18, having been already described in our 
 Tract on Instinct and Intelligence (72), need not be noticed further 
 here. 
 
 Fig. 17.— The Carpenter Bee. Fig. IS.— Nest of the Carpenter Bee. 
 
 (Xylacope). 
 
 47. Another class of this insect has acquired the name of 
 masons, from the circumstance of building their nests of a sort of 
 artificial stone. The situation selected is usually a stone wall, 
 having a southern aspect, and sheltered on either side by some 
 angular projection. The situation being decided upon, the mother- 
 bee proceeds to collect the materials for the mansion, which consist 
 of sand, with some mixture of earth. These she glues together, 
 grain by grain, with a cement composed of viscid saliva, which 
 she secretes. Having formed this material into little masses, 
 like the grains of small shot, she transports them with her 
 mandibles to the place where she has laid the foundation of her 
 mansion. 
 
 "With a number of these masses, united together by an excellent 
 cement secreted by her organs, she first lays the foundation of the 
 building. She next raises the walls of a cell about an inch in 
 length, and half an inch broad, resembling in form a thimble. 
 In this she deposits an egg, fills it with a mixture of pollen and 
 honey, in the same manner as described in the former case, and 
 after carefully covering it in, proceeds to the erection of a second 
 building of the same kind, which she furnishes in the same manner, 
 and so continues until she has completed from four to eight. 
 
 These cells are not placed in any regular order ; some are 
 
 21 
 
THE BEE. 
 
 parallel, others ''perpendicular, and others inclined to the wall at 
 different angles. The whole mass is consolidated by filling up 
 the irregular intersticial spaces between the cells, with the same 
 material as that of which the walls are built. After this has 
 been accomplished, the whole is covered up with coarser grains 
 of sand. 
 
 The nest when thus finished resembles a mass of solid stone, so 
 hard as to be cut with much difficulty by a knife. Its form is an 
 irregular oblong, and to a casual observer presents the appearance 
 of a mere splash of mud rather than that of a regular structure. 
 
 The insects are sometimes so sparing of their labour, that they 
 avail themselves of old nests when they can find them, and often 
 have desperate combats to seize and retain possession of them. 
 
 48. It might be imagined that nests so solidly constructed would 
 afford perfect protection to the young from its enemies ; such is 
 nevertheless not found to be the case. The ichneumon and the 
 beetle both contrive occasionally to deposit their eggs in the cells, 
 the larvae of which never fail to devour their inhabitants. 
 
 Different varieties of the masons select different situations and 
 materials for their nests. Some use fine earth, which they make 
 into mortar with gluten. Others mix sandy earth with chalk. 
 Some construct their nests in chalk-pits, others in the cavities ot 
 large stones, while others bore holes for them in rotten wood. 
 Wherever placed they endeavour to conceal them, by plastering or 
 covering them with some material different from that of which 
 the nest is constructed. Thus one species surrounds its nest with 
 oak-leaves glued to its surface. M. Groureau mentions the case of 
 a bee that employed an entire day, in arranging blades of grass 
 about two inches long, in the form of the top of a tent over the 
 mouth of its nest. A case of this sort was also observed by Mr. 
 Thwaites, who saw a female for a considerable time collecting small 
 blades of grass, which she laid over the empty shell of a snail in 
 which she had located her nest. 
 
 49. The name of upholsterers has been given by Kirby to certain 
 species of bees, who, having excavated their nest in the earth, 
 hang its walls with a splendid coating of flowers and leaves. One 
 of the most interesting of these varieties is the megachile 
 papaveris, which has been described by Eeaumur. It chooses 
 invariably for the hangings of its apartments the most brilliant 
 scarlet, selecting as its material the petals of the wild poppy, 
 which the insect dexterously cuts into the proper form. 
 
 50. Her first process is to excavate in some pathway a burrow 
 cylindrical at the entrance, but enlarged as it descends, the depth 
 being about three inches. After having polished the walls, she 
 next flies to a neighbouring field, where she cuts out the oval 
 
 22 
 
UPHOLSTERERS — LEAP-CUTTERS. 
 
 parts of th.e poppy blossoms, and seizing them between her hind 
 legs returns with them to her cell. Sometimes it happens that 
 the flower from which she cuts these, being but half blown, 
 has a wrinkled petal. In that case she spreads out the folds, and 
 smoothes away the wrinkles, and if she finds that the pieces are 
 too large to fit the vacant spaces on the walls of her little room, 
 she soon reduces them to suitable dimensioias, by cutting off" all 
 the superfluous parts with her mandibles. In hanging the walls/ 
 with this brilliant tapestry she begins at the bottom, and 
 gradually ascends to the roof. She carpets in the same manner 
 the surface of the ground round the margin of the orifice. The 
 floor is rendered warm sometimes by three or four layers of 
 carpeting, but never has less than two. 
 
 Our little upholsterer having thus completed the hangings of 
 her apartment, fills it with a mixture of pollen and honey to the 
 height of about half an inch. She then lays an egg in it, and 
 wraps over the poppy lining, so that even the roof may be fur- 
 nished with this material. Having accomplished this she closes 
 the mouth of the nest.* 
 
 51. It is not every insect of this class which manifests the same 
 showy taste in the colours of their furniture. The species called 
 leaf-cutters hang their walls in the same way, not with the 
 blossoms but the leaves of trees, and more particularly those of 
 the rose-tree. They difler also from the upholsterer, described 
 above, in the external structure of their nests, which are formed 
 in much longer cylindrical holes, and consist of a series of 
 thimble-shaped cells, composed of leaves most curiously convo- 
 luted. "We are indebted likewise to Reaumur for a description of 
 the labours of these. 
 
 52. The mother first excavates a cylindrical hole in a horizontal 
 direction eight or ten inches long, either in the ground or in the 
 trunk of a rotten tree, or any other decaying wood. She fills this 
 hole with six or seven thimble- shaped cells, composed of cut 
 1( aves, the convex end of each fitting into the open end of the 
 ether. Her first process is to form the external coating, which is 
 composed of three or four pieces of larger dimensions than the 
 lest, and of an oval form. The second coating consists of portions 
 of equal size, narrow at one end, but gradually widening towards 
 the other, where the width equals half the length. One side f 
 these pieces is the serrated edge of the leaf from which it was 
 taken, which, as the pieces lap over each other, is kept on the 
 cutside, the edge which was cut being within. 
 
 The little animal next forms a third coating of similar material, 
 
 * Reaumur, vi. 139 to 148. 
 
 23 
 
THE BEE. 
 
 the middle of which, as the most skilful workman would do in a 
 like case, she places over the margins of those that form the first 
 side, thus covering and strengthening the junctions by the expe- 
 dient which mechanics call a break-joint. Continuing the same 
 process she gives a fourth and sometimes a fifth coating to her 
 nest, taking care at the closed end or narrow extremity of the 
 cell, to bend the leaves so as to form a convex termination. 
 
 After thus completing each cell, she proceeds to fill it to within 
 the twentieth of an inch of the orifice with a rose-coloured sweet- 
 meat made of the pollen collected from thistle blossoms mixed 
 with honey. Upon this she lays her egg, and then closes the 
 orifice with three pieces of leaf, one placed upon the other, con- 
 centrical and also so exactly circular in form, that no compasses 
 could describe that geometrical figure with more precision. In 
 their magnitude also they correspond with the walls of the cell with 
 such a degree of precision, that they are retained in their situation 
 merely by the nicety of their adaptation. 
 
 The covering of the cell thus adapted to it being concave, 
 corresponds exactly with the convex end of the cell which is to 
 succeed it, and in this manner the little insect prosecutes her 
 maternal labours, until she has constructed all the cells, six or 
 seven in number, necessary to fill the cylindrical hole. 
 
 53. The process which one of these bees employs in cutting the 
 pieces of leaf that compose her nest, is worthy of attention. 
 Nothing can be more expeditious, and she is not longer about it 
 than one would be in cutting similar pieces with a pair of scissors. 
 After hovering for some moments over a rose-bush, as it were to 
 reconnoitre the ground, the bee alights upon the leaf which she 
 has selected, usually taking her station upon its edge, so that its 
 margin shall pass between her legs. She then cuts with her 
 mandibles, without intermission, in such a direction as to detach 
 from the leaf a triangular piece. When this hangs by the last 
 fibre, lest its weight should carry her to the ground, she spreads 
 her little wings for flight, and the very moment the connection of 
 the part thus cut off with the leaf is broken, she carries it off in 
 triumph to her nest, the detached portion remaining bent between 
 her legs in a direction perpendicular to her body. Thus, without 
 rule or compass, do these little creatures measure out the material 
 of their work into ovals, or circles, or other pieces of suitable 
 shapes, accurately accommodating the dimensions of the several 
 pieces of these figures to each other. What other architect could 
 carry impressed upon the tablet of his memory such details of the 
 edifice which he has to erect, and destitute of square or plumb- 
 line, cut out his materials in their exact dimensions without 
 making a single mistake or requiring a single subsequent correc- 
 24 
 
STEUCTURE OF THE HONEY-COMB. 
 
 tion ? Yet this is what the little bee invariably does. So far are 
 human art and reason surpassed by that instruction which the 
 insect receives from its Divine Creator.* 
 
 54. But of all the varieties of this insect, that of which the 
 architectural and mechanical skill is transcendently the most admi- 
 rable, is the hive-bee. The most profound philosopher, says Kirby, 
 equally with the most incurious of mortals, is filled with astonish- 
 ment at the view of the interior of a bee-hive. He beholds therej 
 a miniature city. He sees regular streets, disposed in parallel 
 directions, and consisting of houses constructed upon the most 
 exact geometrical principles, and of the most symmetrical forms. 
 These buildings are appropriated to various purposes. Some are 
 warehouses in which provisions are stored in enormous quantities. 
 Some are the dwellings of the citizens, and a few of the most 
 spacious and magnificent are royal palaces. He finds that the 
 material of which this city is built, is one which man with all 
 his skill and science cannot fabricate, and that the edifices which 
 it is employed to form are such that the most consummate engineer 
 could not reproduce, much less originate ; and yet this wondrous 
 production of art and skill is the result of the labour of a society 
 of insects so minute, that hundreds of thousands of them do not 
 contain as much ponderable matter, as would enter into the com- 
 position of the body of a man. Quel abime aux yeux du sage 
 qvHune ruche d'abeilles ! Quelle sagesse profonde se cache dans 
 cet abime f Quel philosophe osera le soyider ! K or has the problem 
 thus solved by the bee, yet been satisfactorily expounded by 
 philosophers. Its mysteries have not yet been fathomed. In all 
 ages naturalists and mathematicians have been engrossed by it, 
 from Aristomachus of Soli and Philiscus the Thracian, already 
 mentioned, to Swammerdam, Eeaumur, Hunter, and Huber of 
 modern times. Nevertheless the honey-comb is still a miracle 
 which overwhelms our faculties, f 
 
 55. A honey-comb, when examined, is found to be a flattish 
 cake with surfaces sensibly parallel, each surface being reticulated 
 with hexagonal forms of the utmost regularity. No geometrician 
 could describe the regular hexagon with greater precision than is 
 here exhibited. 
 
 It is proved in geometry that there are only three regular 
 figures, which, being joined together at their corners, will so fit 
 each other as to leave no unoccupied spaces between them. These 
 figures are the square, the equilateral triangle, and the regular 
 hexagon. Four squares united by one of their angles will fill all 
 
 * Reaumur, vi. 971 ; Kirby, Int., i. 377. 
 t Kirby, i. 410. 
 
 25 
 
THE BEE. 
 
 the surroundinp^ space, and any number of squares may thus be 
 combined so as to cover a surface like a mosaic pavement without 
 leaving any inUrmcdiatc unoccupied spaces. 
 
 In like manner six ccjuilateral triangles will have a like pro- 
 I>erty, and in line, throe regular hexagons being similarly united 
 at one of their corners, will in like manner completely occupy the 
 surrounding siiace. 
 
 Since no other reg^ar geometrical figure possesses this property, 
 it follows that a regular mosaic pavement must necessarily be 
 composed of one or other of these figures. 
 
 Fig. 19 represents such a pavement composed of squares; and 
 fig. 20, one composed of equilateral triangles ; and in fine, 
 lig. 21, one composed of regular hexagons. 
 
 Fi- 10. 
 
 The angles, in fig. 19, are 90^; those in fig. 20, are 60°; and 
 those in fig. 21, 120^. No other angles save these, therefore, 
 could be used in any regular pavement of this kind without 
 leaving intersticial uncovered spaces. 
 
 Now it will be at once perceived that the form presented by tlie 
 surface of a honey-comb is that of an hexagonal pavement. We 
 shall presently see why the bee has selected this in preference to 
 cither of the other possible forms. 
 26 
 
HEXAGONAL STRUCTURE. 
 
 56. On further examining tlie comb, it will be found that the 
 hexagonal spaces presented by its surface are the mouths of so 
 
 Fig. 20, 
 
 many hexagonal tubes which are filled with honey. If any of 
 these be empty, it will be seen that the depth of these tubes is 
 half the thickness of the comb. 
 
 67. It appears therefore that the honey-comb is a combination 
 of hexagonal tubes, placed in juxtaposition, the angles of the 
 hexagon being fitted into each other like the stones of a mosaic 
 pavement ; that there are two systems of such tubes, meeting in 
 the middle of the thickness of the comb, their mouths being pre- 
 sented outwards on both sides, and conseq^uently their bases 
 resting against each other. 
 
 If by the dissection of the comb, the forms of their bases be 
 examined, they will be found to consist, not as might be at first 
 supposed of plane regular hexagons, which would be the case if 
 they were plane surfaces at right angles to the tube ; they will 
 he found, on the other hand, to have the form of pyramids, each of 
 which is composed of three regular lozenges united together at 
 their edges, so as to form an apex ; this apex being pointed always 
 towards the opposite side of the comb. The pyramidal base is 
 
 27 
 
THE BEE. 
 
 tlius a geometrical figure, having as much regularity as the 
 hexagonal tube, of which it forms the termination, but constracted 
 
 Fig. 21. 
 
 on a totally different principle. The angles of the lozenges, 
 which form its sides, are one obtuse and the other acute ; and these 
 pyramidal bases of the cells, on one side of the comb, fit into 
 corresponding cavities, made by the similar pyramidal bases of the 
 cells, on the other side of the comb, so as to leave no intermediate 
 unoccupied space. 
 
 58. Without the aid of perspective figures, and even with such 
 aid, without some effort of imagination on the part of the reader, 
 it would be impossible to convey a clear notion of this part of the 
 structure of the honey-comb, and yet without such a clear notion 
 it would be totally impossible to appreciate the admirable results 
 of bee industry. "We have, therefore, attempted to represent in 
 figs. 22 and 23, the bases of four contiguous cells seen from the 
 inside and from the outside. In fig. 22 is presented an inside view 
 of the bases of three adjacent cells, a a a. It must be observed that 
 ^ a o are here intended to represent angular cavities, each formed 
 by the junction of three lozenge-shaped planes, such as have been 
 just described. Now it will be seen, that as a necessary consequence 
 of this juxtaposition, a figure will be formed at &, by three lozenge- 
 28 
 
STllUCTURE OF THE COMB. 
 
 shaped planes, one belonging to each, of the three bases, a a a, 
 and that this, instead of being hollow on the side presented to 
 
 Fig. 22. Fig. 23. Fig. 24. Fig. 25. 
 
 the eye, will be hollow on the opposite side, which is turned from 
 the eye, and will there form an angular cavity precisely similar 
 and equal to the cavities a a a, which are turned towards the eye. 
 Now this cavity, which is thus turned to the opposite side, is the 
 base of one of the cells on the other side of the comb. In fig. 23 
 we have presented a view of the combination as it would be seen 
 on the other side. In this case, the angnlar cavity darkly shaded 
 in the middle of the figure, is the angular projection, &, in fig. 22, 
 seen on the other side ; and the three angular projections which 
 surround it, jutting forward towards the eye, are the three angular 
 bases, a a a, fig. 22, seen on the other side. 
 
 59. A perspective view of a single hexagonal tube or cell, with 
 its pyramidal base, is shown in fig. 24. 
 
 The manner in which the hexagonal cells are united base to 
 base to form the comb, is shown in perspective in fig. 25, where a 
 is the open mouth of the tube, and h c the lozenge-shaped planes, 
 forming the bases of the opposite tubes. The same is shown in 
 section in fig. 26. 
 
 Fig. 26. Fig. 27. Fig. 28, 
 
 60. Several hexagonal cells are shown in their natural juxta- 
 position, placed- base to base, as they form the comb, in fig. 27, 
 and a perspective view of their pyramidal bases is given in fig. 28. 
 
 Nothing can be more surprising than this production of such an 
 insect, when regarded as a piece of scientific engineering. The 
 substance which comprises it being one secreted by the bees in 
 limited quantity, it was of the greatest importance in its use, that 
 a material so scarce should be applied so as to produce the 
 greatest possible result, with the smallest possible quantity of the 
 material. The problem, therefore, which the bee had to solve 
 
 29 
 
THE BEE. 
 
 was, with a given quantity of wax, to construct a coratination of 
 similar and equal cells of the greatest aggregate capacity, and such 
 as to occupy the available space in the hive to the greatest possible 
 advantage. The form and magnitude of the cells must neces- 
 sarily have been adapted to those of the bee itself, because these 
 cells are intended to be the nests in which the eggs are laid and 
 hatched, and the young bee raised to its state of maturity. 
 
 The body of the bee being oblong, and measuring about 
 six-tenths of an inch in length by two-tenths in diameter, cylin- 
 drical tubes of corresponding dimensions would have answered 
 the purpose ; but such tubes could not be united together in 
 juxtaposition without either a great waste of wax or great defi- 
 ciency of strength, since, when placed in contiguity, they would 
 leave between them empty spaces of considerable magnitude, 
 which, if left unoccupied, would render the structure weak, and if 
 filled with wax, would have the double disadvantage of giving 
 needless and injurious weight to the comb, and involving the 
 waste of a quantity of a scarce and precious material, greater than 
 all that would be necessary to form the really useful part of the 
 comb. 
 
 61. From what has been explained it will be understood that, to 
 form a combination of tubular cells without interstices, the 
 choice of the bee was necessarily limited to the three figures 
 already mentioned — the equilateral triangle, the square, and the 
 regular hexagon. The equilateral triangle would be attended 
 with the disadvantage of a great waste of both space and material; 
 for if its dimensions were sufficient to afford easy room to the 
 body of the bee, a large space would be wasted at each of the 
 angles, towards which the body of the bee could never approach. 
 
 A like disadvantage, though less in degree, would have attended 
 square tubes. The bee, therefore, with the instinct of an engineer, 
 decided on the third form, of the regular hexagon, which at once 
 fulfilled the conditions of a sufficiently near adaptation to the 
 form of its own body, and the advantage of such a combination 
 as would leave neither waste space nor loss of material. 
 
 62. In the structure of the comb there is still another point 
 worthy of attention. It might naturally have been expected 
 that it would be composed of a single layer of cells, one side pre- 
 senting the mouth, and the other the pyramidal base ; but if this 
 had been the course adopted, the side consisting of the pyramidal 
 bases would be an extensive surface, upon which the industry of 
 the bee would have no occupation, and the space in the hive to 
 which such surface would be presented would, therefore, be so 
 much space wasted. Instead, therefore, of constructing the 
 comb of a single layer of cells, the bees judiciously make it of a 
 
 30 
 
FORM OF THE CELLS. 
 
 double layer, the pyramidal bases of each layer being placed in 
 contact with each other. 
 
 It might also have been expected that these bases would have 
 received the most simple form of plane surfaces, so that the side 
 of each layer occupied by them would be a uniform plane ; and 
 these planes resting in contact would form the comb ; but to this 
 there would be several objections. In the first place, the capacity 
 of the comb would be less; the bases of the cells, placed in contact, 
 would be liable to slip one upon the other ; and if the cells had a 
 common base, they would have less strength ; but independently 
 of this, the bee itself tapers towards its posterior extremity, and a 
 cell with a flat bottom having no corresponding tapering form 
 would be little adapted to its shape, and would involve a con- 
 sequent waste of space. The bee avoids this disadvantage by 
 giving the bottom of the cell the shape of a hoUow angular 
 pyramid, into the depth of which the tapering posterior extremity 
 of the insect enters. 
 
 63. There is another advantage in this arrangement which 
 must not be overlooked. The pyramidal bases of each layer of 
 cells, placed in juxtaposition by reciprocally fitting each other, so 
 that the angular projections of each are received into the angular 
 cavities of the other, are effective means of resisting all lateral 
 displacement. 
 
 64. Pyramidal bases, however, might have been given to the 
 cells in a great variety of ways, which would have equally served 
 the purposes here indicated ; but it was essential, on grounds of 
 economy, that that form should be selected which would give 
 the greatest possible capacity with the least possible material. On 
 examining curiously the form of the lozenges composing the pyra- 
 midal bases of the cells, Maraldi found by accurate measurement 
 that their acute angle measured 70° 32', and consequently their 
 obtuse angle 109° 28'. Magnitudes so singular as these, invariably 
 reproduced in all the regular cells, could scarcely be imagined to 
 have been adopted by these little engineers without a special pur- 
 pose, and Reaumur accordingly conjectured that the object must 
 have been the economy of wax. 
 
 Not being himself a mathematician suflBciently profound to 
 solve a problem of this order, he submitted to M. Koenig, an 
 eminent geometer of that day, the general problem to determine 
 the form which ought to be given to the pyramidal bottom of an. 
 hexagonal prism, such as those constituting the cones, so that with 
 a given capacity, the least possible material would be necessary 
 for the construction. The problem was one requiring for its solu- 
 tion the highest resources to which analytical science had then 
 attained. Its solution, however, was obtained, from which it 
 
 31 
 
THE BEE. 
 
 appeared that the proper angles for the lozenges would be 70^ 34' 
 for the acute, and consequently 109° 26' for the obtuse angle. 
 Here are then in juxtaposition the result of the labours of the 
 geometer and the bee. 
 
 \ ACUTE ANGLE. 
 
 ! 
 
 OBTUSE ANGLE. 
 
 Bee 
 
 70° 34' 
 70° 32' 
 
 109° 26' 
 109° 28' 
 
 j 
 
 "We leave the reader to enjoy the contemplation of these num- 
 bers without one word more of comment. 
 
 65. Besides the saving of wax effected by the form of the 
 cells, the bees adopt another economical plan suited to the same 
 end. They compose the bottoms and sides of wax of very great 
 tenuity, not thicker than a sheet of writing-paper ; but as walls of 
 this thickness at the entrance would be perpetually injured by the 
 ingress and egress of the workers, they prudently make the margin 
 at the opening of each cell three or four times thicker than the 
 walls. Dr. Barclay discovered that though of such excessive 
 tenuity, the sides and bottom of each cell are actually double, or 
 in other words, that each cell is distinct, separate, and in some 
 measure an independent structure, agglutinated only to the 
 neighbouring cells ; and that when the agglutinating substance 
 is destroyed, each cell may be entirely separated from the rest. 
 This, however, has been denied by Mr. Waterhouse, and seems 
 inconsistent with the account given by Huber, hereafter detailed; 
 but Mr. G. Newport asserts, that even the virgin-cells are lined 
 with a delicate membrane." * 
 
 * Kirby, i. p. 412. 
 
 32 
 
Fig. 5j.— COVERED APIARY. 
 
 THE BEE. 
 
 ITS CHAEACTER AND MANNERS. 
 
 CHAPTEE III. 
 
 66. Drone cells and worker cells. — 67. Store cells. — 68. Construction 
 of combs. — 69. Wax-makers also produce honey. — 70. First 
 operation of the wax-makers. — 71. Process of the foundress. — 
 72. Kneading the wax. — 73. Formation of first wall.— 74. Correction 
 of mistakes. — 75. Dimensions of first wall. — 76. Operations of the 
 nurses. — 77. Bases of cells. — 78. Wax-makers resume their work. 
 — Completion of pyramidal bases. — 79. Pyramidal partition. — 80. 
 Formation of cells. — 81-82. Arrangement of combs. — 83. Sides not 
 parallel. — 84. Process not merely mechanical. — 85-86. Process of 
 construction. — 87. Labour successive. — 88. Dimensions of cells. — 
 89. Their number. — 90. Bee-bread. — 91. Pap for young. — 92. Food 
 adapted to age. — 93. Transformation. — 94. Humble-bees — females. 
 — 95. Their nursing workers. — 96. Transformation. — 97. How the 
 temperature of the cocoons is maintained. — 98. Anecdote related by 
 Huber. — 99. Remarkable care of the nurses. — 100. Heat evolved in 
 respiration by the hive-bee — 101. Cross alleys connecting the streets. 
 — 102. First laying of the queen in Spring. — 103. Her royal suite. — 
 104. The eggs. 
 
 66. Since the population of the hive is composed, as already 
 explained, of different classes of individuals having different 
 stature, and since one of the purposes of the cells is to be their 
 
 Lardner's Museum op Science. d 33 
 
 No. 121. 
 
THE BEE. 
 
 abode from tlie time they issue from the egg until they attain 
 maturity, it follows that the capacity of the cells, or such of them as 
 are thus appropriated, must be subject to a corresponding difference. 
 The cells of the workers wiU therefore be less in magnitude than 
 those of the drones, and these last much less than the royal cells. 
 The comb therefore consists of different parts reticulated by 
 hexagons of different magnitudes, the smaller ones being the 
 mouths of the cells appropriated to the workers, and the larger 
 those of the cradles of the drones. As to the royal cells they differ 
 altogether from the others, not only in capacity, but also in position 
 and form. As already explained, the general forms of the cells 
 are hexagonal tubes, with pyramidal bases, and open mouths 
 ranged horizontally, their axes being at right angles to the flat 
 sides of the comb. The comb itself is placed vertically in the 
 hive, and the royal cells which are large and pear-shaped are 
 cemented to its lower edges, hanging from it vertically like stalac- 
 tites from the roof of a cavern. Although there be but one queen 
 in each hive, she produces, nevertheless, thi-ee or four or more, 
 and sometimes even as many as thirty or forty royal eggs. The 
 princesses which issue from these, are destined to be the queens of 
 the successive swarms which the hive sends forth. 
 
 67. The cells which are appropriated exclusively to the storage 
 of honey and pollen, are similar in form and position to those 
 appropriated to the young drones and workers, but are greater in 
 length, and this length the bees vary according to the exigencies 
 of their store of provisions. If more of these result from their 
 labours than the cells constructed can contain, and there is not 
 time or space for the construction of more cells, they lengthen 
 the honey-cells already made by cementing a rim upon them. 
 They sometimes also use for storage, cells which have already been 
 occupied by young drones or workers, which, having attained their 
 state of maturity, have vacated them. 
 
 68. Having thus explained in general the forms and structures 
 of the cells, we shall briefly explain the operation by which the 
 bees construct them, and by their combination form the combs. 
 
 The material of the combs is wax, a substance secreted beneath 
 the ventral segments of the bodies of that class of the workers 
 which, from this circumstance, has received the name of wax- 
 makers. The apparatus by which the material which ultimately 
 acquires the character of wax is secreted, consists of four pairs of 
 membranous bags, called wax-pockets, which are situated at the 
 base of each segment of the body, one on each side, and which 
 in the natural condition of the body, are concealed by the seg- 
 ments overlapping each other. They can, however, be rendered 
 visible by drawing out the body longitudinally, so that the part 
 34 
 
CONSTEUCTION OF COMBS. 
 
 of each segment covered by tlie preceding one sliall be disclosed 
 <fig. 29). 
 
 In tbese pockets the substance to be ultimately converted into 
 wax is secreted from the food taken into the stomach, which, 
 transpiring from thence through the membrane of 
 the wax-pocket, is formed there in. thin laminae. 
 The stomach and its appendages which are en- 
 dowed with these functions, though much less 
 capacious in the nurses than in the wax-makers, 
 is not altogether absent ; and the nurses have a 
 certain limited power of secreting wax. In them 
 the wax-making function, however, seems to exist 
 in little more than a rudimentary state. 
 
 69. Although the chief duty of the wax-makers 
 is that from which they have taken their names, they are also 
 capable of producing honey, and when the hive is abundantly 
 furnished with combs, they accordingly change the object of their 
 industry and produce honey instead of wax, 
 
 70. When a comb is about to be constructed, the operation is 
 commenced by the wax-makers, who, having taken a due portion 
 of honey or sugar, from either of which wax can be elaborated. 
 
 Fig. 30. suspend themselves one to ano- 
 
 ther — the claws of the fore-legs 
 of the lowermost being attached 
 to those of the hind-legs of the 
 next above them, so that they 
 form a cluster, the external sur- 
 face of which presents the appear- 
 ance of a fringed curtain (fig. 30). 
 After having remained in this 
 state unmoved for about twenty- 
 four hours, during which period 
 the material of the wax is secreted, the thin laminae into which it is 
 formed may generally be perceived under the abdomen. 
 
 A single bee is now seen to separate itself from the cluster and 
 to pass from'among its companions to the roof of the hive, where 
 by turning itself round, it clears a circular space for its work, 
 about an inch in diameter. Having done this, it proceeds to lay 
 the foundation of a comb in the following manner, if one may be 
 permitted to apply the word foundation to the top of a suspended 
 structure. 
 
 71. The foundress bee, as this individual is called, commences 
 its work by seizing with one of its hind feet a plate of wax, 
 or rather of the material out of which wax is to be constituted, 
 from between the segments of its abdomen. The insect is 
 
 d2 25 
 
THE BEE. 
 
 represented in this act in fig. 31. Having fi.xed a secure hold on 
 the lamiQa, it carries it by its feet from the abdomen to its mouth, 
 where it is taken by one of the fore-legs which holds it vertically 
 while the tongue rolled up serves for a support, and by raising 
 and depressing at will, causes the whole circumference to be 
 brought successively under the action of the mandibles (fig. 32), 
 so that the margin is soon ground into pieces. These pieces fall 
 gradually as they are detached in the double cavity of the 
 mandibles which are bordered with hair. 
 
 Fig. 31. Fig. 32. 
 
 The mandibles or jaws which execute this process open in a 
 horizontal, instead of a vertical, direction as in the case of the 
 superior animals, and have a form resembling that of a pair of 
 shears or scissors. 
 
 72. The fragments of the laminae thus divided falling on either 
 side of the mouth, and pressed together into a compact mass, 
 issue from it in the form of a very narrow ribbon. This ribbon 
 is then presented to the tongue by which it is impregnated with 
 a frothy liquor, which has the same efiect upon it as water has 
 on potter's earth in the formation of porcelain paste. That this 
 process, by which the raw material of the wax is worked and 
 kneaded, is an extremely elaborate and artificial one, is rendered 
 apparent by observing carefully the manoeuvres of the bee's tongue 
 in the process. Sometimes that organ assumes the form of a 
 spatula, or apothecary's knife, sometimes it takes the form of a 
 mason's trowel, and sometimes that of a pencil tapering to a point, 
 never ceasing to work upon the ribbon which is being evolved 
 from the mouth in these several forms. 
 
 After the ribbon has been thus thoroughly impregnated with 
 moisture, and carefully kneaded, the tongue again pushes it 
 between the mandibles, but in a contrary direction to that in which 
 it previously passed, when the whole is worked up anew. 
 
 The substance is now converted into true wax, the characteristic 
 properties of which it has acquired in this process. The material 
 evolved in laminae from the segments of the abdomen is brittle 
 and friable, and would be as unfit for the structure of the comb 
 as dry potter's earth would be for the formation of a vase. The 
 liquid secreted from the mouth, with which it has been impreg- 
 36 
 
CONSTRUCTION OF COMBS. 
 
 nated, and the elaborate process of kneading wliicli it has under- 
 gone, have totally changed its mechanical properties and have 
 imparted to it that ductility and plasticity so eminently charac- 
 teristic of wax. It has also undergone other physical changes. 
 The laminse taken from the abdominal segments are colourless 
 and transparent, the substance into which they are converted 
 being white and opaque. 
 
 73. The pieces of wax thus elaborated the insect applies against^ 
 the roof of the hive, arranging them with her mandibles in the 
 intended direction of the comb. She continues thus until she 
 has in this way applied the wax produced from the entire laminae, 
 when she takes in lilie manner another from her abdomen, treat- 
 ing it in the same way. After thus heaping together all the wax 
 wMch her organs have secreted, and causing it to adhere by its 
 proper tenacity to the vaults of the hive, she withdraws from her 
 work and is succeeded by another labourer who continues the 
 same operations, who is followed in a like manner by a third and 
 fourth, and so on, all disposing the produce of their labour in the 
 direction first intended to be given to the comb. 
 
 74. Nevertheless it would seem that the curious facility by 
 whicli these proceedings are directed is not altogether unerring, for 
 it happens by chance now and then that one of the workers will 
 commit a mistake by placing the wax in the wrong direction. In 
 such cases, the worker which succeeds never fails to rectify the 
 error, removing the materials which are wrongly placed, and 
 disposing them in the proper direction. 
 
 75. The result of all these operations of the wax-makers is the 
 construction of a rough wall of wax about half an inch long, a 
 sixth of an inch high, and the twenty-fourth of an inch thick, 
 which hangs vertically from the roof of the hive. In the first 
 rough work there is no angle nor the least indication of the 
 form of the cells. It is a mere straight and plain vertical parti- 
 tion of wax, roughly made, about the twenty-fourth of an inch 
 thick, and such as can only be regarded as the foundation of a 
 comb. 
 
 76. The duty of the wax-makers terminating here, they are 
 succeeded by the nurses, who are the genuine artisans ; standing 
 in relation to the wax-makers in the same manner as, in the con- 
 . struction of a building, the masons who work up the materials into 
 the form of the intended structure would to the common labourers. 
 One of the nurses commences its operation by placing itself hori- 
 zontally on the roof of the hive, with its head presented to the 
 wall of wax constructed by the wax-makers. This wall or 
 partition is intended to be converted into the system of pyramidal 
 bases of the cells already described, and accordingly the first 
 
 37 
 
THE BEE. 
 
 labour of the nurses is directed to accomplish this change. Their 
 first operation, therefore, is to mould on that side of the wall to 
 which its head is directed, a pyramidal cavity having the form of 
 the base of one of the intended cells. When it has laboured for 
 some minutes thus, it departs and is succeeded by another, who 
 continues the work^ deepening the cavity and increasing its lateral 
 margins by heaping up the wax on either side by means of its 
 teeth and fore-feet, so as to give the sides a more regular form. 
 More than twenty nurses succeed each other in this operation. 
 
 77. It must be remembered that during this process, nothing 
 has been done on the other side of the partition, but when the 
 cell just described has attained a certain length, other nurses 
 approach the opposite side of the partition and commence the 
 formation of the pyramidal base of two cells corresponding in 
 position with that just described, and these in like manner prose- 
 cute their labours, constantly relieving each other. 
 
 78. While the nurses are thus employed in converting the rough 
 partition into the pyramidal bases of cells, and in forming the 
 hexagonal tubes corresponding to these pyramidal bases, the wax- 
 makers return and, reaming their labour, increase the magnitude 
 of the partition in every direction, the nurses meanwhile still 
 prosecuting their operations. 
 
 After having worked the pyramidal bases of the cells of one 
 row into their proper forms, they polish them and give them a 
 high finish, while others are engaged in laying out the next 
 series. 
 
 79. In fig. 33, is represented one of the faces of such a partition 
 
 Fig. 33. Fig, 34. 
 
 as is here described, after it has been formed into a continuous 
 system of pyramidal bases. These are intended to represent the 
 bases of the cells of the workers. A similar piece showing the 
 bases of the cells of the drones is represented in fig. 34. 
 
 80. The cells themselves, consisting, as already explained, of 
 38 
 
CONSTKUCTION OF COMBS. 
 
 hexagonal prismatic tubes, are the next objects of the industry 
 and skill of the nurses. These are cemented on the borders of the 
 pyramidal cavities shown in figs. 26 and 27. 
 
 81. The surfaces represented in figs. 33 and 34 having a contour 
 very unequal, the edges of the pyramidal cavities being inclined to 
 each other, so as to form angles alternately salient and re-entrant, 
 the first work of the bees is to form those parts of the prismatic sides 
 of the cells which are necessary to fiU up the re-entrant angles of/ 
 the contours of the pyramidal bases. When this has been accom-l 
 plished, the contours of all the hexagonal divisions extended over 
 the surface of the partition, represented in figs. 33 and 34, are 
 brought to a common level, and from that point the labour of the 
 little artificers becomes more simple, consisting of the construction 
 of the oblong rectangles which form the remainder of the six sides 
 of each cell. 
 
 82. It must nevertheless be remarked, that the first row of 
 cells, being necessarily attached to the roof of the hive, and not 
 at its upper edge connected like the other rows with other similar 
 cells, has an exceptional form, these being not hexagonal, but 
 pentagonal ; two of the sides of the ordinary cells being replaced 
 by the roof of the hive, as shown in figs. 33 and 34. A corre- 
 sponding exceptional form is of course also given to the bases of 
 the first row of cells. 
 
 The combs constructed in this manner are ranged in vertical 
 planes parallel one to the other in the hive, as shown in per- 
 spective in fig. 35, in vertical section in fig. 36, and in horizontal 
 
 Fig. 35. Fig. 36. 
 
 section in fig. 37. They are not always ranged strictly in single 
 parallel lines ; but are sometimes bent at an angle, as shown in 
 fig. 37. 
 
 An end view of a comb, showing the mouths of the cells fore- 
 shadowed by perspective, is represented in fig. 38. 
 
 83. The flat sides of a comb are not strictly parallel, but 
 
 39 
 
THE BEE. 
 
 generally slightly inclined one to the other, so that the thickness 
 gradually diminishes from top to bottom, as shown in the vertical 
 section, fig. 36. This gradation of thickness is continued to a 
 
 Fig. 37. Fig 38. 
 
 certain point, while the width of the comb is continually aug- 
 mented; but so soon as the workers obtain sufficient space to 
 lengthen it, it begins to lose this form, and the surfaces become 
 sensibly parallel. 
 
 84. A certain class of naturalists, who have directed their at- 
 tention to the history of this insect, appear to have taken a 
 pleasure in forming hypotheses, by which it would be reduced to 
 a mere machine. Thus, according to them, the formation of the 
 various parts of the comb would result from a mere mechanical 
 necessity, the organs of the insect being supposed to be so formed 
 that the difierent parts of the cells would receive their forms by a 
 mechanical process, as in certain operations in the arts the most 
 exact geometrical forms are imparted to materials by punches and 
 dies expressly made for the purpose. 
 
 Between such expedients and the organs of this admirable 
 insect, there is, however, not the remotest analogy. 
 
 The mechanical instruments with which they work are the 
 feet, the mandibles, and the tongue, the operations of which are 
 guided by the antennae, which are feelers of exquisite sensibility. 
 They do not remove in their operations a single particle of wax, 
 until the surface to be sculptured has been carefully explored by 
 the antennae. These organs are so flexible and so easily applied 
 to all parts, however delicate, of their workmanship, that they 
 are capable of performing the offices of square and compass, 
 measuring the minutest parts with the utmost precision, so as to 
 guide the work in the dark, and produce with unerring precision 
 that wondrous structure called the comb. 
 
 85. If is impossible to behold a dissected comb without per- 
 ceiving the geometrical necessity which connects one part with 
 
 40 
 
CONSTRUCTION OP COMBS. 
 
 anotlier. In tlie formation of such, a structure, chance can have 
 no share. The original mass of wax is augmented hy the labour 
 of the wax-makers in the exact quantity which is necessary ; and 
 these wax-makers, who thus are constantly on the Avatch to 
 observe the progress of the comb, so as to keep the artificer-bees 
 constantly supplied with the necessary quantity of raw material, 
 are themselves utterly destitute of the art and science necessary to 
 construct the cells. , 
 
 86. The bees never commence the construction of two contiguous! 
 and parallel combs together, for the obvious reason, as it should 
 seem, that to make one parallel to and at a given distance from 
 another, the actual formation of one must be first accomplished to 
 a certain point. They therefore begin by the middle comb ; and 
 when that has been constructed to a certain depth, measured from 
 the top of the hive, two other combs, parallel to it and at regu- 
 lated distances from it at either side, are commenced ; and when 
 these again are completed to a certain depth, two others outside 
 these are commenced, and so on. This order of proceeding is 
 attended with a further advantage by preventing the workers on 
 one comb from being inconveniently crowded or obtruded upon 
 by those of the adjacent combs. 
 
 87. The labour of the bees is conducted in common, but not 
 always simultaneously. Every partial operation is commenced 
 by one individual bee, who is succeeded in her labours by others, 
 each appearing to act individually in a direction depending on the 
 condition in which she finds the work when it falls into her hands. 
 The whole band of wax-makers, for example, is in complete 
 inaction until one of them goes forth to lay the foundation of a 
 comb. Immediately the labours of this one are succeeded and 
 seconded by the others, and, when their part is done, an individual 
 nurse-bee goes to lay out the plan of the first cell, and is in like 
 manner succeeded continuously by others. 
 
 88. The diameter of the cells intended for the larvae of the 
 workers is alway 2§ lines, and that of those meant for the 
 larvae of the males or drones 3i lines. The male-cells are gene- 
 rally in the middle of the combs, or in their sides; rarely in 
 their upper part. They are never insulated, but form a corre- 
 sponding group on both sides the comb. When the bees form 
 male-cells below those of neuters, they construct many rows of 
 intermediate ones, the diameter of which augments progressively 
 tin it attains that of a male-cell; and they observe the same 
 method when they revert from the male-cells to those of workers. 
 It appears to be the disposition of the queen which decides the 
 kind of cells that are to be made ; while she lays the eggs of 
 workers, no male-cells are constructed ; but when she is about to 
 
 41 
 
THE BEE. 
 
 lay the eggs of males, the workers appear to know it, and act 
 accordingly. When there is a very large harvest of honey, the 
 hees increase the diameter and even the length of their cells. At 
 this time many irregular combs may be seen with cells of twelve, 
 fifteen, and even eighteen lines in length. Sometimes, also, they 
 have occasion to shorten the cells. When they wish to lengthen an 
 old comb, the sides of which have acquired their full dimensions, 
 they gradually diminish the thickness of its edges, gnawing down 
 the sides of the cells till it assumes the lenticular form ; they 
 then engraft a mass of wax round it, and so proceed with new 
 cells." * 
 
 89. The number of cells contained in the combs of a well- 
 stocked hive is considerable. In a hive twenty inches high and 
 fourteen inches diameter, they often amount to forty or fifty 
 thousand. A piece of comb, measuring fourteen inches long and 
 seven inches wide, containing about 4000 cells, is frequently con- 
 structed in twenty- four hours. 
 
 90. Nothing can be more admirable than the tender solicitude 
 and foresight shown by the bee towards its off'spring. Although 
 these insects provide a great number of cells, as storehouses, for the 
 honey intended for the use of the community, yet the object which 
 more exclusively engrosses them is the care of their young, to the 
 provision and rearing of which they sacrifice all personal and 
 selfish considerations. In a new swarm, accordingly, the first 
 care of these insects is to construct cradles for their young, and 
 the next, to provide an ample store of a peculiar sort of papf 
 called bee-bread, for their food. 
 
 This bee-bread consists of the pollen of flowers, which the 
 workers at this time are incessantly employed in gathering, flying 
 from flower to flower, brushing from the stamens their yellow 
 treasure, which they collect in the little baskets with which their 
 hind-legs are so admirably provided. They then hasten back to 
 the hive, where, having deposited the store thus collected, they 
 return to seek a new load. 
 
 Another troop of labourers are in constant attendance in the 
 Live to receive the stock of bee-bread thus collected, which they 
 carefully store up until suoh time as the queen has laid her eggs. 
 These eggs she places in an upright position in the bottoms of the 
 cells, where they are severally hatched. 
 
 91. The bee-bread is converted into a sort of pap, or whitish 
 jelly, by being swallowed by the bee, in the stomach of which it is 
 probably mixed with honey and then regurgitated. 
 
 The moment the young brood issue from the eggs in the state of 
 larvae, they are diligently fed with this jelly by the class of bees 
 * Kirby, i. 419. 
 
 42 
 
ORGANS OF THE BEE. 
 
 called nurses, who attend tliem with all the solicitude implied by 
 their title, renewing the pap several times a day, as fast as it is 
 consumed. 
 
 The curious observer will see, from time to time, different 
 nurses introduce their heads into the cells containing the young. 
 If they see that the stock of pap is not exhausted, they imme- ^ 
 diately withdraw and pass on to other cells ; but if they find, Qif 
 the contrary, the provision consumed, they never fail to deposit! a 
 fresh supply. These nurses go their rounds all day long in rapid 
 succession thus surveying the cradles, and never stopping except 
 where they find the supply of food nearly exhausted. 
 
 92. That the duty of these tender nurses is one which requires 
 the exertion of some skill will be understood, when it is stated 
 that the quality of food suitable to the young varies with their age. 
 "When they first emerge from the egg the jelly must be thin and 
 insipid, and, according as they approach to maturity, it requires 
 to be more strongly impregnated with the saccharine and acid 
 principles. 
 
 Not only does the food of the larva thus require to be varied 
 according to its age, but the food to be supplied to different larvae 
 is altogether different. The jelly destined for the larvse which, 
 are to become queens, is totally different from that prepared for 
 those of drones and workers, being easily distinguished by its 
 sharp and pungent flavour ; and it is probable, also, that the jelly 
 appropriated to the drones differs from that upon which the 
 workers are reared. 
 
 These insects, moreover, exhibit as much economy as skill; 
 the quantity of food provided being as accurately proportioned to 
 the wants of the young as its quality is to their varying functions. 
 So accurately is the supply proportioned to the wants of the larvae, 
 that, when they have attained their full growth and are about to 
 undergo their final metamorphosis into nymphs, not an atom of 
 bee-bread is left unconsumed. 
 
 93. At the epoch of this metamorphosis, when the nymph needs 
 seclusion to spin its cocoon, and has no further occasion for food, 
 these tender nurses, with admirable foresight, terminate their cares 
 by sealing up each cell, enclosing the nymph with a woven lid. 
 
 In all the maternal cares described above, neither the drones nor 
 the queen participate. These duties fall exclusively upon the 
 workers, and are divided between them, as has been explained, the 
 task of collecting the bee-bread being appropriated to one set, and 
 that of feeding and tending the young to another. This duty has no 
 cessation ; as the queen lays her eggs successively and constantly, 
 the young arrive successively at the epoch of their first metamor- 
 phosis; and, consequently, so soon as some are sealed up and 
 
 43 
 
THE BEE. 
 
 abandoned by the nurses to spin their cocoons, others issue from, 
 the egg and demand the same maternal care ; so that these nurses 
 spend their whole existence in the discharge of the offices here 
 described. 
 
 94. Although the organisation of other species of the bee does 
 not approach to the perfection of the hive-bee here described, it is 
 nevertheless worthy of attention and study. 
 
 The humble-bees, which so far as respects their social policy, 
 compared with the hive-bee, may be regarded as rude and un- 
 civilised rustics, exhibit nevertheless marks of affection for their 
 young quite as strong as their more polished neighbours. 
 
 Unlike the queen of the hive, the females take a considerable 
 share in the education of the young. When one of these provident 
 mothers has constructed with great labour and much skill a com- 
 modious woven cell, she furnishes it with a store of pollen moist- 
 ened with honey, and, having deposited six or seven eggs in it, 
 carefully closes the opening and all the interstices with wax ; but 
 her maternal cares do not end here. By a strange instinct, pro- 
 bably necessary to restrain an undue increase of the population, 
 the workers, while she is laying her eggs, endeavour to seize 
 them, and, if they succeed, greedily devour them. Her utmost 
 vigilance and activity are scarcely sufficient to save them ; and it 
 is only after she has again and again repelled the murderous 
 intruders, and pursued them to the furthest verge of the nest, 
 that she succeeds in accomplishing her object ; and even when she 
 has sealed up the cell containing them, she is obliged to continue 
 to guard it for six or eight hours ; since otherwise the gluttonous 
 workers would break it open and devour the eggs. The mother is 
 conscious, however, by a heaven -inspired knowledge, of the time 
 when the eggs will cease to excite the appetites of the depredators. 
 
 After this the cells remain unmolested until the larva issues 
 from the eggs. The maternal cares having, there ceased, the 
 workers, before so eager to devour the eggs, now assume the 
 character of nurses. They know the precise hour when the larvae 
 will have consumed the stock of food, provided for them by 
 maternal care, and from that time to the period of their maturity 
 these nurses continually feed them with honey or pollen, introduced 
 in their proboscis through a small hole in the cover of the cell 
 opened for the purpose, and then carefully closed. 
 
 95. These nursing-workers also perform another duty of a most 
 curious and interesting description. As the larva increases in 
 size, the cell, which has been appropriated to it, becomes too small 
 for its body, and in its exertions to obtain room it splits the thin 
 woven walls which confine it. The workers, who are constantly 
 on the watch for this, lose no time in repairing the breach, which 
 
 44 
 
HUMBLE-BEES. 
 
 they patch up with wax as often as the fracture takes place, so 
 that in this way the cell increases in size until the larva arrives 
 at maturity. 
 
 96. As in the case of the hive-bee already described, the larva 
 after the first metamorphosis, is shut up in the enlarged cell to 
 spin its cocoon. When this labour has been completed, and that 
 the perfect insect is about to issue, the workers still discharging* 
 the duty of tender foster-parents, set about to assist the littl^ 
 prisoner in cutting open the cocoon, from which it emerges in its 
 perfect state. 
 
 97. While in the pupa state, however, another tender and con- 
 siderate measure of the workers must not be passed without notice. 
 It is essential to the well-being of the pupa that while concealed 
 in the cocoon it should be maintained at a genial temperature. 
 To secure this object, the workers collect upon the cocoons in cold 
 weather and at night, so that by brooding over them they may 
 impart the necessary warmth. 
 
 98. The following curious anecdote connected with this subject 
 is related by Huber. 
 
 "He put under a bell-glass about a dozen humble-bees, 
 without any store of wax, along with a comb of about ten silken 
 cocoons, so unequal in height that it was impossible the mass 
 should stand firmly. Its unsteadiness disquieted the humble-bees 
 extremely. Their affection for their young led them to mount 
 upon the cocoons for the sake of imparting warmth to the enclosed 
 little ones, but in attempting this the comb tottered so violently 
 that the scheme was almost impracticable. To remedy this 
 inconvenience, and to make the comb steady, they had recourse 
 to a most ingenious expedient. Two or three bees got upon the 
 comb, stretched themselves over its edge, and with their heads 
 downwards fixed their fore-feet on the table upon which it stood, 
 whilst with their hind-feet they kept it from faUing. In this con- 
 strained and painful posture, fresh bees relieving their comrades 
 when weary, did these affectionate little insects support the comb 
 for nearly three days. At the end of this period they had pre- 
 pared a sufficiency of wax, with which they built pillars that kept 
 it in a firm position : but by some accident afterwards, these got 
 displaced, when they had again recourse to their former manoeuvre 
 for supplying their place ; and this operation they perseveringly 
 continued, until M. Huber, pitying their hard task, relieved them 
 by fixing the object of their attention firmly on the table." * 
 
 It is impossible not to be struck with the reflection, that this 
 most singular fact is inexplicable on the supposition, that insects 
 are impelled to their operations by a blind instinct alone. How 
 * Linnsean Trans., vi. 247, et seq. 
 
 45 
 
THE BEE. 
 
 could mere macMnes have tlius provided for a case wMch. in a 
 state of nature has probably never occurred to ten nests of humble- 
 bees since the creation ? If in this instance these little animals 
 were not guided by a process of reasoning, what is the distinction 
 Tjetween reason and instinct ? How could the most profound 
 architect have better adapted the means to the end — how more 
 dexterously shored up a tottering edifice, until his beams and his 
 props were in readiness ? * 
 
 99. The following remarkable example of the care bestowed by 
 the nurses in keeping the pupa warm, more especially dm-ing the 
 day which immediately precedes its exit from the cocoon as a 
 perfect insect — an epoch, when as it would seem it is more 
 especially necessary that it should be maintained at an elevated 
 temperature, — was supplied by Mr. Newport. That naturalist 
 observed that in the process of incubation, the humble-bee at that 
 particular stage increased considerably the force of its respiration. 
 To render the purpose of this intelligible to the reader not accus- 
 tomed to physiological enquiries, it may be necessary to state that 
 in the act of respiration the oxygen, which is one of the constitu- 
 ents of the atmosphere, enters into combination with the carbon 
 and hydrogen, which compose part of the body of the animal. 
 Now this combination being identical with that which produces 
 heat in a common coal fire or the flame of a lamp, the same 
 effect is produced in the animal economy from the same cause ; 
 and hence it arises that the development of heat in the body is 
 always so much the greater, in proportion to the increased activity 
 of respiration. 
 
 100. To return to the hive-bee, it was observed by Mr. Newport 
 that in the early stage of the incubation of the pupa, the rate of 
 respiration of the insect is very gradual, but becomes more and 
 more frequent as the epoch approaches at which it issues from the 
 cocoon; the number of respirations per minute then amounting 
 to 120 or 130. 
 
 Mr. Newport states that he has seen a bee upon the combs con- 
 tinue perseveringly to respire at that rate for eight or ten hours, 
 until its temperature was greatly increased and its body bathed 
 in perspiration. When exhausted in this way it would retire 
 from its maternal duty and give place to another foster-mother, 
 who would proceed in the same way to impart warmth to the 
 pupa. 
 
 In one case Mr. Newport found that while the thermometer in 
 the external air stood at 70*2, it rose on the lips of these cells 
 which were not brooded upon at the moment, to 80*2, but when 
 placed in contact with the bodies of the brooding bees, it rose 
 * Kirby, Int., i. 320. 
 
 46 
 
FIEST LAYING OP THE QUEEK 
 
 to 92*5. It appears therefore that by the voluntary increase of 
 their respiration they were enabled to impart to the nymph 
 enclosed in the cocoon 12 '3 additional degrees of heat.* 
 
 101. In every well-filled hive the combs are ranged in parallel 
 planes, as shown in figs. 36, 37 ; and that no space may be lost, 
 while at the same time sufficient room is left for the movements 
 of the workers, the open spaces between the parallel combs leave 
 a width just sufficient to allow two- bees easily to pass each other. 
 These open spaces are the streets of the apiarian city, the high- 
 ways along which the building materials are carried while the 
 combs are in process of construction, through which the supply of 
 provisions is carried to the stores, and food to the young, who are 
 being reared in the cells. 
 
 But since the nurses must tend the cells of all the combs, and 
 therefore pass successively and frequently from street to street, 
 they would be compelled to descend to the lower edge of the comb 
 to arrive at an adjacent street, unless cross alleys were provided 
 at convenient points to abridge such journeys. The prudent 
 architects foresee this in laying out their city, and make such 
 passages, alleys, or arcades, by which the bees can pass from any 
 street to the adjacent parallel street, without going the long way 
 round. 
 
 102. On the return of spring, when the genial temperature of the 
 weather begins to produce its wonted effects on vegetation, and 
 when the vernal plants which the bees love begin to put forth 
 their foliage and flower, the busy population of the hive re- 
 commence their labours ; and the queen, who has passed the 
 winter in repose, attended by her devoted subjects, and feeding 
 on the stores laid up by them during the previous season, com- 
 mences laying her great brood of eggs. At this epoch she is 
 much larger than at the cessation of her laying in the autumn. 
 Before she deposits an egg, she examines carefully the cell 
 destined for it, putting her head and shoulders into it, and 
 remaining there for some time, as if to assure herself that the 
 cradle of her offspring has been put in proper order. Having 
 satisfied herself of this, she withdraws her head, and introducing 
 the posterior extremity of her abdomen deposits a single egg upon 
 the pyramidal base of the ceU, which adheres there in the manner 
 already described. 
 
 She then passes to another empty cell, where, after the same 
 precautions, she deposits another egg, and so continues, sometimes 
 committing to the cells two hundred eggs and upwards in the day. 
 
 103. In this operation, so essential to the maintenance of the 
 population, she is assiduously followed and most respectfully 
 
 * PhilosopMcal Trans., 1837, p. 296. 
 
 47 
 
THE BEE. 
 
 surrounded by a certain train of her subjects, appointed apparently 
 to attend her, and form the ladies-in-waiting on the occasion. They 
 range themselves in a circle around her (fig. 39). From time to time 
 
 Fig. 39.— The queen depositing her eggs in the cells, surrouuded by her suite. 
 
 the individuals of her suite approach her and present her with 
 honey. They enter the cells where the eggs have been deposited, 
 and carefully clean them, and prepare them for the reception of 
 the pap which is to feed the young when it issues from the egg. 
 
 104. In some exceptional cases, where her majesty is rendered 
 over prolific by any accidental cause, the eggs will drop from her 
 faster than she can pass from cell to cell, and in such cases two 
 or more eggs will be deposited in the same cell. Since the cells 
 are constructed only of sufficient magnitude for the due accom- 
 modation of a single bee, the royal attendants in such cases 
 always take away the supernumerary eggs, which they devour, 
 leaving no more than one in each cell (fig. 40). 
 
 The eggs are oval and oblong, about the twelfth of an inch in 
 length, of a bluish white colour, and a little bent. They are 
 hatched by the natural warmth of the hive (from 76" to 96° Fahr.), 
 in from three to six days, the interval depending on the tem- 
 perature of the weather. 
 
 48 
 
Fig. 58.— VILLAGE HIVES. 
 
 THE BEE. 
 
 ITS CHARACTER AND MANNERS. 
 
 CHAPTEE ly. 
 
 105. Tte larvse. — 106. Transformation of worker nymph. — 107. Worker 
 cells. — 108. Treatment of a young worker. — 109. Of the drone. — 110. 
 Drone nymph. — 111. Hoyal cell and nymph. — 112. Its treatment. — 
 113. Honey cells. — 114. Pasturage— progress of work. — 115. Con- 
 struction of comb. — 116. Remarkable organisation. — 117. Magnitude 
 and weight of bees. — 118. Character of queen. — 119. Royal jealousy. 
 — 120. Principle of primogeniture, — 121. Assassination of rivals. — 
 122. Battle of virgin queens. — 123. Reason of mutual hostility. — 
 124. Result of the battles. — 125. Battle of married queens. — 126. 
 Battle of a virgin with a fertile queen. — 127. Sentinels at the gates. 
 Treatment of an intruding queen.— 128. Remarkable proceeding of 
 bees that have lost their queen — effect of her restoration. — 129. 
 Effect of the introduction of a new queen. — 130. Policy of the hive. — 
 131. Operations at the beginning of a season. 
 
 105. The larva wMch issues from the egg is a white grub, des- 
 titute of legs, haying its body divided transversely by a series of 
 parallel circular grooves into annular segments. When it has 
 Lardner's Musetjh of Science. e 49 
 
 No. 123. 
 
THE BEE. 
 
 Fig. 43. 
 
 grown so as to toucli the .opposite angle of the cell, it coils itself 
 up in the form of a circular arc, or as Swammerdam describes 
 it, like a dog going to sleep. It floats 
 Fi 40 ^^^^^ ^ whitish transparent fluid, pro- 
 ' vided for it by the nurses, on which it 
 probably feeds during this early stage of 
 its life. Its dimensions are gradually en- 
 Fig. 41. larged until its extremities touch one ano- 
 ther, so as to form a complete ring, fig. 41, 
 in the base of the cell. In this state the 
 grub is fed with the pap or bee bread 
 already mentioned. The slightest move- 
 ment on the part of the nursing bees is- 
 sufficient to attract its attention, and it 
 eagerly opens its little jaws to receive the 
 oflered nourishment, the supply of which, 
 presented by the nurse, is liberal without being profuse. 
 
 The growth of the larva is completed in from four to six days, 
 according to the temperature of the weather. In cool weather 
 the development takes two days more than in warm weather. 
 
 When it has attained its full growth, it occupies the whole 
 breadth and a great part of the length of the cell. The nurses at 
 this time knowing that the moment has 
 arrived at which the first metamor- 
 phosis, in which the grub is changed 
 into a nymph, takes place, discontinue 
 the supply of food, and close up the 
 mouth of the ceU by a light brown 
 waxen cc^er, which is convex externally^ 
 This convexity of the cover is greater in the drone cells than 
 in those of the workers. The covers of the honey cells are, on 
 the contrary, made paler in colour, and quite flat or even a little 
 concave externally. 
 
 When the larva has been thus enclosed, it immediately com- 
 mences, like the silk-worm, to spin a cocoon. In this labour it is 
 incessantly employed, lining the sides of its cell and encasing its 
 own body in a white silken robe. The threads which form this 
 mantle issue from the middle of the under lip of the nymph, as 
 the insect in this intermediate- state between that of the grub and 
 the perfect bee is caUed. This thread consists of two filaments, 
 which, issuing from two adjoining orifices in the spinner, are then 
 gummed together. 
 
 106. The nymph of a worker spins its robe in thirty-six hours, 
 and after passing three days in this preparatory state, it undergoes 
 -so great a change as to lose every vestige of its previous form. It 
 50 
 
METAMORPHOSES. 
 
 is clothed with a harder coating, with dark brown scales, fringed 
 with light hairs. Six annular segments are distinguished on its 
 abdomen, which are inserted one into another like the joints of a 
 telescope tube, and give the insect the power of elongating and 
 contractiQg itself within certain limits. The breast is also 
 invested with a sort of brush of grey feathery hairs, which as age 
 advances assume a reddish hue. In about twelve days aU the 
 parts of the body of the perfect insect are developed, and can be 
 seen through the semi-transparent robe in which it is clothed. 
 
 About the twenty-first day, counting from that on which the 
 egg was laid, the second metamorphosis is complete, and the 
 perfect insect, gnawing through the cover of its 
 cell, issues into life, leaving behind it the silken ^'i?- 45. 
 
 robe which it wore in the intermediate state of 
 nymph. This is closely attached to the inner 
 surface of the cell in which it was woven, and 
 
 forms a permanent lining of it. By this cause pupa of a worker, 
 the breeding cells become smaller and smaller, 
 as the eggs are successively hatched in them, until at length 
 their capacity becomes too limited for the full development of the 
 nymphs. They are then turned into store rooms for honey. 
 
 107. In fig. 46 is represented apiece of comb, consisting exclu- 
 sively of workers' cells, in different states. Several, c, c, c, &c., are 
 closed, the nymph not having yet undergone its final metamorphosis. 
 A bee having arrived at the perfect state and gnawed open the 
 
 Fig. 46. 
 
 cover of its ceU, is shown at m. The cells, h, A, have their 
 openings on the opposite side of the comb, and g, g, are cells 
 from which the perfect insects have already issued. 
 
 e2 51 
 
THE BEE. 
 
 108. "When a young bee, after its final metamorpTiosis, has issued 
 from the cell, the nurses crowd round it, carefully brushing it, 
 giving it nourishment and showing it the way through the hive. 
 Others meanwhile are occupied in cleaning the cell from which 
 it has issued and putting it in order to receive another egg if it 
 be still large enough, and if not, to receive a store of honey. 
 
 The young bee is not sufficiently strong to fly on the first day. 
 It is only on the morrow, after being well fed and brushed down 
 by the nurses, and having taken a walk from time to time through 
 the combs, that it ventures on the wing. 
 
 109. The drone passes three days in the egg, and continues to 
 receive the care of the nurses as a grub until the tenth day, when it 
 passes into the state of nj'^mph, and is sealed up in its cell by the 
 
 Fig. 47. 
 
 nurses with a very convex cover. As already stated, the drone 
 grub being larger than that of the worker, the cell assigned to it 
 is proportionately more capacious, and the cover by which as a 
 nymph it is shut up is much more convex externally. A piece of 
 comb consisting of drone cells is shown in fig. 47. 
 
 Some cells, o, o, o, being those from which the perfect insect 
 has issued, are open and empty. 
 
 Near the borders of the comb, where local circumstances render 
 it necessary to modify the principles of its architecture so as to 
 accommodate the cells to their position in the hive, may be 
 52 
 
METAMOKPHOSES. 
 
 observed several, h, 7t, of unusual and irregular forms. "While 
 some such cells have six unequal sides, others have only four or 
 live. It seems also that in the case of certain cells intended only 
 for the reception of honey, the bee is not at all as scrupulous in 
 the observance of architectural regularity as in the case of brood 
 cells. 
 
 110. The drone nymph undergoes its final metamorphosis and 
 becomes a perfect insect, from the twenty-fifth to the twenty- , 
 seventh day from that on which the egg is laid, according to tlie| 
 temperature of the hive. It is therefore six or seven days later 
 in arriving at maturity than the worker. 
 
 111. The changes to which the young of the royal family are 
 subject before arriving at maturity, are different from those above 
 stated. It has been already explained that the royal cells are 
 vertical instead of being horizontal, are egg-shaped instead of 
 being hexagonal, and in fine are much more capacious than those 
 
 X 
 
 Fig. 48. 
 
 of the drones or workers. One of these dells is shown at r s in 
 fig. 48, a part, ti u, being removed to show the royal nymph 
 within it. It will be observed that a much larger space is given 
 to the royal nymph than is allowed either to that of the worker 
 or the drone, the bodies of which nearly fill their respective ceUs. 
 The royal nymph is always placed, as shown in the figure, with 
 her head downwards. 
 
 The progressive formation of a royal cell is shown in fig. 49. 
 It is unfinished, as at a, when the egg, is deposited ; and is gradually 
 enlarged, c, as the grub increases in size ; and is sealed up, b, when 
 it is transformed into a nymph. 
 
 5S ■ 
 
THE BEE. 
 
 The grub issues from the egg on the third day, becomes a 
 nymph from the eighth to the eleventh day, and undergoes its 
 
 Fig. 49. 
 
 final metamorphosis, becoming a perfect insect on the seventeenth 
 day. It is, however, sometimes detained a prisoner in the cell 
 for seven or eight days longer. 
 
 112. Naturalists are not agreed as to some of the circumstances 
 attending the treatment of the young, which we have here given 
 on the authority of Feburier and other French entomologists. 
 Mr. Dunbar, in reference to the circumstances attending the first 
 issuing of the perfect insect from the cell, says that in hundreds 
 of instances their situation has excited his compassion, when 
 after long struggling to escape from its cradle, it has at last 
 succeeded so far as to extrude its head, and when labouring with 
 the most eager impatience, and on the very point of extricating 
 its shoulders also, which would have at once secured its exit, a 
 dozen or two of workers, in following their avocations, have 
 trampled without ceremony over the struggling creature, which 
 was then forced for the safety of its head, quickly to pop down 
 again into the cell and wait until the unfeeling crowd had passed, 
 before it could renew its efforts. Again and again will the same 
 impatient efforts be repeated by the same individual, and with 
 the same mortifying interruptions, before it succeeds in obtaining 
 its freedom. Not the slightest attention or sympathy on the part 
 of the workers in these cases was ever observed by Mr. Dunbar, 
 nor did he ever witness the parental cares and sage instruction 
 given to the young which are described by the French 
 entomologists. 
 
 54: 
 
ROYAL NYMPH. 
 
 Positive, however, is more entitled to consideration than 
 negative testimony, and it cannot be doubted that Feburier and 
 others witnessed those cares, guidance, and education which they 
 have so well described. Besides, Dr. Bevan admits that he has 
 seen assistance rendered to the infant drones. So soon as the 
 young insect has been cleanea of its exuviae and regaled with 
 honey by the nurses, the latter clean out the cell exactly as we 
 have already described. 
 
 113. A piece of comb is shown in fig. 50, the upper part a, of 
 which contains honey-cells closed with fiat sides of wax. The 
 cells, c c, &c., contain pollen, and c' c', &c., propolis. The cells 
 
 Fig. 50. 
 
 of the upper part are those which originally belonged to workers, 
 and those of the lower part, with convex covers, are occupied by 
 the drone nymphs. 
 
 114. The various flowers and herbs which supply the materials 
 for honey, wax, and propolis taken collectively, are called the 
 pasturage of the bees, and it is observed that when this pasturage 
 is very abundant, the bees, eager to profit by the rich harvest, 
 depart from their habit of conveying their booty first to the 
 uppermost cells of the comb, so as to fill them gradually down- 
 wards. On the contrary, upon arriving with their load, and eager 
 to return for a f^esh supply, they unload themselves in the nearest 
 €mpty cells they can find. The wax-makers meanwhile charge 
 
 55 
 
THE BEE. 
 
 themselves with the labour of taking the provisions thus deposited 
 from the lower to the upper parts of the combs. 
 
 115. In fig. 51, is shown a piece of comb in process of construc- 
 tion. It has, as usual, an oval form. The wax, of wliich it is 
 formed, is white, but as it advances in age it takes successively a 
 
 Fig. 51. 
 
 darker and darker colour, being first yellow, then reddish, and 
 sometimes even becomes blackish. The sides of the cells are 
 gradually thickened, by the constant adhesion and accumulation 
 of the cocoons, of which the nymphs successively bred in them are 
 divested. The top and sides of the comb are every where 
 strongly cemented, by a mixture of propolis and wax, to the roof 
 and sides of the hive. These structures are almost never known 
 to fall except by some accidental cause external to the hive, such 
 as a blow or the too intense heat of the sun dissolving the 
 cement. 
 
 116. The character and manners of the bee lave an intimate 
 relation with its social organisation. We have seen that in the 
 56 
 
WEIGHT OF BEES. 
 
 building of their city this organisation is never for a moment lost 
 sight of. The chambers vary in number, magnitude, form, and posi- 
 tion. Those designed for the members of the royal family are few 
 and exceptional, those for the drones much more numerous, but 
 about one hundred times less numerous than those of the workers. 
 The magnitudes are in like manner strictly regulated, in relation, 
 to the volume of the body of the occupant, except the royal 
 chambers to which a magnitude is given much greater in propor- 
 tion than that of the bodies of the royal tenants. The object to 
 be attained by this increased capacity, as well as by the vertical 
 position specially given to the royal cells, has not been ascertained. 
 
 117. How little relation there exists between mere bodily 
 magnitude, and the faculties which govern acts so remarkable as 
 those of the insects now before us, will be understood when it is 
 stated that, according to the experiments of Reaumur, the average 
 weight of the bee is such that 336 go to an ounce, and 5376 to 
 a pound ; and John Hinton found that 2160 workers would not 
 more than fill a common pint. 
 
 118. Having thus explained in a general way the persons com- 
 posing the society, and the structure and architecture of their 
 dwellings, we shall proceed to notice some of the more remarkable 
 traits of their character and manners. 
 
 It has been already explained that the community of the hive 
 bees is strictly a female monarchy. The jealous Semiramis of the 
 hive, as Kirby observes, will have no rival near her throne. It 
 may, therefore, be asked to what purpose are the sixteen or 
 twenty princesses reared, for whom royal chambers are provided, 
 and who are treated in all respects by the nurses as aspirants to 
 the throne ? This will be comprehended, however, when it is 
 remembered that the hive, soon after the commencement of the 
 season, becomes so enormously over-peopled, that emigration 
 becomes indispensable, and that with each emigrant swarm a 
 queen is necessary. Either therefore the queen regnant must go 
 forth, abdicating the throne, in which case it is ascended by the 
 eldest of the princesses, or the latter is raised to the sovereignty @f 
 the emigrating colonj^ Now, since a rapid succession of swarms 
 issue from the hive, especially in the early part of the season, 
 sometimes as many as four in eighteen days, and since one queen 
 is required for each, a proportionately numerous royal family is 
 required to fill so many independent thrones. 
 
 119. When the growth of several princesses and their arrival 
 at maturity occurs, before the increase of the population renders 
 emigration necessary, so as to create thrones for them, the most 
 violent jealousy is' excited in the breast of the queen regnant, 
 who is either mother or sister to these several queens presumptive, 
 
 57 
 
THE BEE. 
 
 and her royal breast is fired with agitation, nor does she rest until 
 she has engaged in mortal conflict with her rivals, and either puts 
 them to death or suffers death at their hands. 
 
 120. When a hive, having lost its queen by emigration or other- 
 wise, is provided with several royal cells, which generally happens, 
 the first princess which issues from these in the perfect state im- 
 mediately ascends the throne in right of primogeniture. Although 
 her rivals are not yet in a condition to dispute the title, they, 
 nevertheless, excite her jealousy in the highest degree. Scarcely 
 ten minutes elapse from the moment she has attained the perfect 
 state, and issued from the royal cell, when she goes in quest of the 
 other royal cells, assails with fury the first she encounters, and 
 having gnawed a large hole in it she introduces the posterior 
 -extremity of her abdomen, and kills her rival with her sting. 
 
 121. A crowd of workers, who are passive spectators of this, ap- 
 proach the cell, and enlarging the breach, drag out the corpse of the 
 murdered princess, who, in such cases, has already assumed the 
 perfect state. If the queen attack in like manner a cell of which 
 the occupant is still in the state of nymph, she does not waste her 
 strength in slaying it, well knowing that its premature exposure 
 will do the work of death. The workers, in this case also enlarg- 
 ing the breach made by the queen, pull out the nymph, who 
 immediately perishes. 
 
 122. Huber, who witnessed, and has described all these curious 
 proceedings, being desirous to ascertain what would happen if two 
 rival queens, both in the perfect state, found themselves together 
 in the same hive, produced artificially that contingency on the 
 15th May, 1790. He managed to provide in the same hive 
 royal cells, in an equal stage of forwardness, so that virgin 
 queens issued from two of them almost at the same moment. 
 
 When they appeared in presence of each other they fell upon 
 each other with all the appearance of insatiable fury, and so 
 engaged one with the other, that each held in her mandibles the 
 antennae of the other. They were engaged breast to breast, and 
 abdomen to abdomen, so that if each had put forth her sting, 
 mutual death would have been the consequence. But as if nature 
 had forbidden this mutual destruction, the combatants disengaged 
 themselves from each other's grasp, and fied one from the other 
 with the greatest precipitation. 
 
 Huber says that this was not a mere incident which might have 
 ■occurred in a single case, but would not occur in others, for he 
 Tepeated the same experiment frequently, and it was always 
 followed by the same result. It seemed, therefore, as though it 
 were a case foreseen by nature, and that one only of the 
 •combatants should fall in such combats. 
 58 
 
BATTLE OF QUEENS. 
 
 123. Nature has ordained that in each hive there shall be one, 
 and but one queen, and when by any concurrence of circumstances 
 a second appears, one or the other is doomed to destruction. But it 
 is not permitted to the common class of the people to do execution 
 on a royal personage, since in that case it might not be possible to 
 secure unanimity as to the particular queen who is to be preserved, 
 so that different assemblages of the people might at the same time 
 assail different queens, and so leave the hive without a sovereign. 
 It was, therefore, necessary, as Huber argues, that the extermina- 
 tion of the superfluous queens should be left to the queens them- 
 selves, and that they should in their combats be filled with an 
 instinctive horror of mutual destruction. 
 
 Some minutes after the two queens above mentioned had 
 separated and retired from each other, and when their fears had 
 time to subside, they again prepared to approach each other. 
 They engaged once more in the same position, involving the 
 danger of mutual destruction, and as before, once again separated 
 and mutually fled each other. 
 
 124. During all this time the greatest agitation prevailed among 
 the population who assisted at the scene, more especially when the 
 two combatants separated. On two different occasions the workers 
 interfered to prevent them from flying from one another. They 
 arrested them in their flight, seizing them by the legs and detain- 
 ing them prisoners for more than a minute. In fine, in a last 
 attack, one of the queens, more active and furious than the other, 
 taking her rival unawares, laid hold of her with her mandibles 
 at the insertion of the wing, and then mounting on her back, 
 and bringing the posterior extremity of her abdomen to the 
 junction of one of the abdominal segments of her adversary, 
 stabbed her mortally with her sting. She then let go the wing 
 which she had previously held and withdrew her sting. 
 
 The vanquished queen fell, dragged her body slowly along for 
 a certain distance, and soon after expired. 
 
 125. Having thus ascertained the conduct of virgin queens under 
 the circumstances here described, Huber made arrangements for 
 observing the conduct of queens who were in a condition to pro- 
 duce eggs. For this purpose he placed a piece of comb on which 
 three royal cells had been constructed in a hive with a laying 
 queen. The moment they caught her eye she fell upon them, 
 opened them at their bases, and surrendered them to the 
 attendant workers, who lost no time in dragging out the royal 
 nymphs, greedily devouring the store of food which remained in 
 the cells, and sucking whatever was in the carcases. Having 
 accomplished this they proceeded to demolish the cells. 
 
 It was now resolved to ascertain what would be the behaviour of 
 
 59 
 
THE BEE. 
 
 a queen-mother regaant in case a stranger queen pregnant were 
 introduced into the hive. A mark having been previously made 
 upon the back of such a queen, so that she might be afterwards 
 identified, she was placed in the hive. Immediately on her 
 appearance the workers collected in a crowd around her, and 
 formed as usual a circle of which she was the centre, the heads of 
 all the remaining crowd being directed towards her. This very 
 soon became so dense that she became an absolute prisoner 
 within it. 
 
 While this was going on, a similar ring was formed by another 
 group of workers round the queen regnant, so that she was 
 likewise for the moment a prisoner. 
 
 The two queens being thus in view of each other, if either 
 evinced a disposition o approach and attack the other, the two 
 rings were immediately opened, so as to give a free passage to the 
 combatants ; but tha moment they showed a disposition to fly 
 from each other, the rings were again closed, so as to retain them 
 in the spot they occupied. 
 
 At length the queen regnant resolved on the conflict, and the 
 surrounding crowd, seeming to be conscious of her decision, 
 immediately cleared a passage for her to the place where the 
 stranger stood perched on the comb. She threw herself with 
 fury on the latter, seized her by the root of the wing, and fixed 
 her against the comb so as to deprive her 
 of all power of movement or resistance, 
 and then bending her abdomen inflicted 
 a mortal stab with her sting, and put an 
 end to the intruder. 
 
 126. A fruitful queen full of eggs was 
 next placed upon one of the combs of a hive 
 over which a virgin queen already reigned. 
 She immediately began to drop her eggs, 
 but not in the cells ; nor did the workers, 
 by a circle of whom S'he was closely surrounded, take charge of 
 them ; but, since no trace of them could be discovered, it is 
 probable that they were devoured. 
 
 The group, by which this intruding queen was surrounded, 
 having opened a way for her, she moved towards the edge of the 
 comb, where she found herself close to the place occupied by the 
 legitimate virgin queen. The moment they perceived each other, 
 they rushed together with ungovernable fury. The virgin, 
 mounting on the back of the intruder, stabbed her several times 
 in the abdomen, but failed to penetrate the scaly covering of the 
 segments. The combatants then, exhausted for the moment, 
 disengaged themselves and retired. After an interval of some 
 60 
 
SENTINELS AT THE GATES. 
 
 minutes they returned to the charge, and this time the intruder 
 succeeded in mounting on the back of the virgin and giving her 
 several stabs with her sting, which, however, failed to penetrate 
 the flesh. The virgin q[ueen, succeeding in disengaging herself, 
 again retired. Another round succeeded, with the like results, 
 the virgin still coming undermost, and, after disengaging herself, 
 again retiring. The combat appeared for some time doubtful, 
 the rival queens being so nearly equal in strength and power, 
 when at last, by a lucky chance, the virgin sovereign inflicted a 
 mortal wound upon the intruder, who fell dead on the spot. 
 
 In this case, the sting of the virgin was buried so deep in the 
 flesh of her opponent, that she found it impossible to withdraw it, 
 and any attempt to do so by direct force would have been fatal to 
 her. After many fruitless efibrts she at length adopted the 
 following ingenious expedient with complete success. Instead of 
 exerting her force on the sting by a direct pull, she turned herself 
 round, giving herself a rotatory motion on the extremity of her 
 abdomen where the sting had its insertion, as a pivot. In this 
 way she gradually unscrewed the sting. 
 
 127. The gates of the hive are as constantly and regularly 
 guarded night and day as those of any fortress. The workers 
 charged with this duty are, of course, regularly relieved. They 
 scrupulously examine every one who desires to enter ; and, as 
 though distrustful of their eyes, they touch all visitors with their 
 antennae. If a queen happens to present herself among such 
 visitors, she is instantly seized and prevented from entering. 
 The sentinels grasp her legs or wings with their mandibles, and 
 so surround her that she cannot move. As the report of the event 
 spreads through the interior of the hive, large reinforcements of 
 the guard arrive, who augment the dense ranks which hold the 
 strange queen in durance. 
 
 In general, in such cases, the intruding queen is thus detained 
 prisoner until she dies from want of food. It is remarked that 
 the guard, who thus surround and detain her, never use their 
 stings upon her. In one instance Huber attempted to extricate s 
 ■queen, thus surrounded, by taking her directly out of the ring of 
 guards. This excited the rage of the guard to such a pitch that, 
 putting forth their stings, they rushed blindly not only on the 
 queen but on each other. The queen, as well as several of the 
 guard, were killed in the melee. 
 
 128. "When the sovereign of the hive is removed or accidentally 
 destroyed, the population seem at first to be wholly unconscious 
 of their loss, and pursue their usual avocations as if nothing had 
 happened. But after the lapse of some hours they begin to 
 manifest a certain degree of uneasiness. This gradually increases, 
 
 61 
 
THE BEE. 
 
 until the entire hive becomes a scene of tumult. The wax- 
 makers abandon their work, the nurses desert the infant brood ; 
 they run here and there in all directions through the streets and 
 passages of the hive as if in delirium. That all this disorder 
 and alarm is produced by the report spreading that the sovereign 
 has disappeared, was proved to demonstration by Huber, who 
 restored to the hive the queen he had purposely withdrawn. 
 Her majesty was instantly recognised by those who happened to- 
 be assembled at the place of her restoration ; but what is remark- 
 able is that the intelligence of her return was immediately spread 
 through every part of the hive, so that the bees in its most remote 
 streets and alleys, who had no opportunity of personally seeing 
 her majesty, were informed of her re-appearance, as was proved, 
 by the restoration of order and tranquillity, and the resumption 
 of their usual labours by all classes of the population. 
 
 129. If, instead of restoring to the hive the queen herself, a new 
 queen, stranger to the population, be introduced, she will not. 
 at first be accepted. She will, on the contrary, be guarded and 
 imprisoned by a ring of bees, in the same manner as a strange 
 queen is treated in a hive which still retains its reigning sovereign. 
 But if she survives sixteen or eighteen hours in this confinement, 
 the guard around her gradually disperses itself, and the lady 
 enters the hive and assumes without further question the state 
 and dignity of queen, and becomes the object of the homage paid, 
 to the sovereign. 
 
 As we have already stated, the first work which the population- 
 undertakes, after being assured of the loss of its queen, is directed 
 to obtain a successor to her. If there be not royal cells prepared, 
 they set about their constructicto. "While this work was in 
 progress, and in twenty-four hours after their queen had been 
 taken from them, Huber introduced into the hive a fruitful queen 
 in the prime of life, being eleven months old. Not less than 
 twelve royal cells had been already commenced and were in a 
 forward state. The moment the strange queen was placed on 
 one of the combs, one of the most curious scenes commenced which 
 was probably ever witnessed in the animal world, and which has 
 been described by Huber. 
 
 The bees who happened to be near the stranger approached her,, 
 touched her with their antennae, passed their probosces over 
 all parts of her body, and presented her with honey. Then they 
 retired, giving place to others, who approached in their turn and 
 went through the same ceremony. All the bees who proceeded 
 thus clapped their wings in retiring and ranged themselves in a. 
 circle round her, each, as it completed the ceremony, taking a 
 position behind those who had previously ofi'ered their respects. A 
 62 
 
POLICY OF THE HIVE. 
 
 general agitation was soon spread on those sides of the comhs corre- 
 sponding with that of the scene here described, From all quarters, 
 the bees crowded to the spot, and each group of fresh arrivals, 
 broke their way through the circle, approached the new aspirant 
 to the throne, touched her with their antennae and probosces, 
 offered her honey, and, in fine, took their rank outside the circle 
 previously formed. The bees forming this sort of court circle 
 clapped their wings from time to time, and fluttered apparently 
 with self-gratification, but without the least sign of disorder or 
 tumult. 
 
 At the end of fifteen or twenty minutes from the commence- 
 ment of these proceedings the queen, who had hitherto remained 
 stationary, began to move. Tar from opposing her progress or 
 hemming her in, as in the cases formerly described, the bees, 
 opened the circle on the side to which she directed her steps,, 
 followed her, and, ranging themselves on either side of her path,, 
 lined the road in the same manner as is done by military bodies, 
 in state processions. She soon began to lay droiie eggs, for whicli. 
 she sought and found the proper cells in the combs which had 
 been already constructed. 
 
 While these things were passing on the side of the comb where' 
 the new queen had been placed, all remained perfectly tranquil 
 on the opposite side. It seemed as though the bees on that side 
 were profoundly ignorant of the arrival of a new queen on the 
 opposite side. They continued to work assiduously at the royal 
 cells, the construction of which had been commenced on that side 
 of the comb, just as if they were ignorant that they had no 
 longer need of them ; they tended the grubs in those cells where- 
 the eggs had been already hatched, supplying them as usual, 
 from time to time, with Royal Jelly. But at length the new 
 queen in her progress arriving at that side of the comb, she was 
 received by those bees with the same homage and devotion of 
 which she had been already the object at the other side. They ap- 
 proached her, coaxed her with their antennae and probosces, offered 
 her honey, formed a court circle round her when she was stationary,, 
 and a hedge at either side of her path when she moved, and proved 
 how entirely they acknowledged her sovereignty by discontinuing 
 their labour at the royal cells, which they had commenced before 
 her arrival, and from which they now removed the eggs and 
 grubs, and ate the provisions which they had collected in them. 
 
 From this moment the queen reigned supreme over the hive,, 
 and was treated in all respects as if she had ascended the throne 
 in right of inheritance. 
 
 130. Most of the prDceedings of these curious little societies are 
 explicable by what seems a general social law among them, to 
 
 68 
 
/ 
 
 THE BEE. 
 
 suffer no individuals or class to continue to exist, save such, as are 
 necessary in one way or another to the well-being of the actual 
 community, or the continuance of the species. This principle 
 once admitted, we find explanations satisfactory enough of all the 
 circumstances attending the conduct of the queen regnant towards 
 the royal princesses, of the population generally to the several 
 members of the royal family, and, in fine, of the workers towards 
 the drones. 
 
 The royal family, as we have seen, are all fertile females, and 
 their sole function is to assume the throne of the hive itself, or 
 of the colonies called swarms, which, successively issue from it, 
 and thus placed to become the fruitful mothers of thousands, 
 which will continue the race and form future colonies. 
 
 The drones have no other function than that of kings consort 
 presumptive, either of the hive itself or of the colonies which 
 successively emigrate from it. As has been explained, one only 
 is chosen as consort by each queen. So long as the swarming 
 season continues, a sufficient body of drones are wanted to supply 
 the necessary troop of suitors to each emigrant princess. But 
 when the last swarm of the season has gone forth, and the queen 
 regnant has long since made her choice and celebrated her 
 nuptials, the drones are no longer useful to the general popula- 
 tion, and become the objects of a general massacre. 
 
 131. After the close of the winter, and at the commencement of 
 the first fine days of spring, the active life of the society recom- 
 mences. A well peopled hive is then always provided with a 
 fertile queen, who has held the sovereignty since the close of 
 the preceding season. In the months of April and May she begins 
 to lay drone eggs in great numbers. This is called the great 
 laying. 
 
 While she is thus engaged depositing her eggs in the larger 
 class of hexagonal cells, previously constructed for their reception, 
 the workers, well knowing that the deposition of royal eggs will 
 speedily follow, occupy themselves in constructing a number of 
 those cells of oval shape and vertical position, (fig. 49,) which 
 have been already described. 
 
 64 
 
Fig. 56. — THE CABINET BEE-HOUSE, 
 
 THE BEE. 
 
 ITS CHAEACTER AND MANNERS. 
 
 CHAPTEE Y. 
 
 132. Change of state of the queen aftei' laying, — 133. First swarm led by 
 her majesty. — 134. Proceedings of the first swarm. — 135. Loyalty 
 and fidelity to the queen— remarkable experiment of Dr. Warder. — 
 136. Interregnum after swarming. — 137. The princess royal. — 138. 
 Second swarm — its effects. — 139. Successive swarms. — 140. Pro- 
 duction of a factitious queen — Schirach's discovery. — 141. Factitious 
 queens dumb. — 142. Factitious princesses allowed to engage in mortal 
 combat.' — 143. Homage only offered to a married queen. — 144. Re- 
 .spect shown to her corpse. — 145. Functions of the drones.— 146. 
 Their treatment. — 147. Their massacre described by Huber. — 148. 
 Case in which no massacre took place. — 149. Character and habits of 
 the workers. — 150. Products of their labours. — 151. Process of work. 
 152. Honey and pollen — nectar and ambrosia. — 153. Bee the priest 
 who celebrates the marriage of the flowers. — 154. Why the bee 
 devotes each excursion to one species of flower. — 15.5. Unloading the 
 workers. — 156. Storage of spare provision. — 157. Radius of the circle 
 of excursion. 
 
 Lardner's Museum of Science. v 65 
 
 No. 125. 
 
THE BEE. 
 
 To make tliis great laying of drone eggs, her majesty must be 
 at least eleven months old. Supposing that she has been hatched 
 the preceding season in February, she will lay during that sea- 
 son workers' eggs almost exclusively, producing at the most from 
 fifty to sixty drone eggs. But after the winter, at the epoch 
 now referred to, the hive being then filled exclusively with 
 workers, and standing in absolute need of drones to supply 
 suitors to the future queens, she produces drone eggs constantly 
 and exclusively imtil the commencement of the swarming season, 
 with the exception, however, of a limited number of royal eggs, 
 which she deposits at intervals more or less distant in the royal 
 cells just now mentioned, which the workers occupy themselves 
 in constructing during the great laying. 
 
 The great laying usually continues for about a month, and it 
 is about the twentieth or twenty-first day that the workers begin 
 to lay the foundations of the royal cells. They generally build 
 from sixteen to twenty of them, and sometimes even as many as 
 twenty- seven. When these cells have attained the depth of two- 
 tenths to three-tenths of an inch, the queen deposits in each of 
 them successively a royal egg. Now since the princesses which 
 are to issue from these eggs are destined to ascend the thrones of 
 the emigrant colonies, which are to issue in succession from the 
 hive, it is important that they should arrive at maturity at suc- 
 cessive intervals, corresponding as nearly as possible with the 
 emigration of the swarms. 
 
 The queen acts as if she were conscious of this, for she 
 deposits the royal eggs, not like the drone or worker eggs in rapid 
 and uninterrupted succession, but after such intervals as will 
 insure their arrival at maturity in that slow succession, which 
 will correspond nearly or exactly with the issue of the successive 
 swarms. 
 
 132. It has been already explained that the nurses seal up the 
 cells, at the time at which the grub is ready to undergo its meta- 
 morphosis into a nymph. In accordance with this, and with the 
 successive deposition of the royal eggs, jiist described, the times of 
 sealing up the series of royal cells are separated by intervals 
 corresponding with those of the deposition of the royal eggs. 
 
 Before the commencement of the great laying, the abdomen of 
 the queen is so enlarged that her movements are seriously impeded, 
 and she would be altogether unable to fly. According as the 
 laying proceeds, she becomes smaller and smaller, and when it 
 has been completed, the royal eggs having been meanwhile depo- 
 sited at regulated intervals, as above described, her majesty 
 recovers her natural form and dimensions, and with them her full 
 bodily activity. This change in the condition of the queen, and 
 66 
 
FIRST SWARM. 
 
 ithe simultaneous deposition of fifteen hundred to two thousand 
 drone eggs, and some sixteen or twenty royal eggs, are intimately 
 •connected with the approaching social state of the colony. 
 
 133. It was shown by Huber, and since confirmed by other ob- 
 servers, that it is a constant law of bee politics that the first swarm 
 •of the season shall be led by the queen-regnant, who therefore ab- 
 dicates her native throne in favour of the colonial sovereignty. This 
 -swarm takes .place when the grub proceeding from the first of the 
 ueggs deposited 'by ^the queen in the royal cells, as above described, 
 ihas undergone its .transformation into a nymph.* The necessity 
 ■for this law is thus explained by Huber. Without it, the mutual 
 •conflict of the queen-regnant and the princesses, as they would be 
 successively developed, would render the emigration of swarms 
 impassible. For as each princess would issue perfect from the cell, 
 she would be attacked, and forced to engage in combat with the 
 queen, who being, by reason of her age, the stronger and more 
 powerful, would be always victorious. Thus princess after prin- 
 cess would be destroyed, and none would be forthcoming to 
 take the thrones of the successive emigrating colonies. To pre- 
 vent such a catastrophe, nature has therefore wisely ordered that 
 the queen-regnant, by leading forth the first swarm of the season, 
 should remove all cause of danger to the succession of princesses. 
 
 134. When the emigrant swarm thus first sent forth from the 
 parent hive has established itself, the first care of the workers is to 
 construct combs, consisting of workers' cells. They labour assidu- 
 ously at these, and in accordance with this the queen, who has 
 already deposited in the original hive her full brood of drone 
 ■eggs, soon begins in her new city to deposit a brood of worker 
 -eggs ; workers being then the first and most pressing want of the 
 colony. This laying begins as soon as the cells are ready for the 
 deposition of the eggs, and continues for ten or twelve days. 
 About the latter part of this interval, the bees occupy themselves 
 in the construction of the larger class of hexagonal cells for the 
 ■drone eggs. It would seem as though they knew that her majesty 
 would at this time lay a certain number of such eggs. She 
 ■accordingly commences laying these, though in far less number 
 than in the great laying, but still sufficient to prepare her people 
 for the succeeding deposition of royal eggs, for which they con- 
 struct meanwhile a suitable number of royal cells. 
 
 ^ It rarely happens, at least in the country where Huber made 
 his observations, that the original queen leads forth a swarm from 
 ithe new hive. The thing nevertheless occasionally occurs, and 
 when it does, it takes place in three or four weeks after the 
 
 * Huber, i. 279. 
 p2 
 
 67 
 
THE BEE. 
 
 original swarm, and is attended with circumstances precisely 
 similar. 
 
 135. Let us now return to the original hive and see what took 
 place there after the departure and abdication of the reigning 
 queen. 
 
 As examples proving the loyalty and fidelity of the bees to their 
 queen, Dr. Bevan quotes some remarkable and interesting cases 
 supplied by Dr. Warder. That apiarist being desirous of ascer- 
 taining the extent of the loyal feeling among these little people, 
 hazai ded the loss of a swarm in an experiment made with that 
 object. Having shaken on the grass all the bees from a hive 
 which they had tenanted only the preceding day, he carefully 
 sought for and quietly caught the queen. Then placing her with 
 a few attendants in a box, he took her into his parlour, where the 
 lid being removed, she and her attendants immediately flew to 
 the window, when he clipped off one of her wings, returned her 
 to the box and confined her there for more than an hour. 
 
 In less than a quarter of an hour the swarm ascertained the 
 loss of their queen, and instead of clustering together in a single 
 mass as usual, like a bunch of grapes, they spread themselves 
 over a sjjace of several feet, were much agitated, and uttered a 
 plaintive sound. An hour afterwards they all took flight and 
 settled upon the hedge where they had first alighted after leaving 
 the parent stock, but instead of clustering together in a single 
 bunch, as when the queen accompanied them, and as swarms 
 usually hang, they extended themselves thirty feet along the 
 hedge in small bunches of forty or fifty or more. 
 
 The queen was now presented to them, when they quickly 
 gathered round her with a joyful hum, and formed one harmonious 
 cluster. At night t^e Doctor hived them again, and on the next 
 morning repeated the experiment to see whether the bees would 
 rise. The queen being in a mutilated state, and unable to accom- 
 pany them, they surrounded her for several hours apparently 
 willing to die with her rather than abandon her in her distress. 
 The queen was a second time removed, when they spread them- 
 selves out again, as though in search of her. Her repeated 
 restoration to them at difierent parts of their circle produced one 
 uniform result, and these poor loving and loyal creatures always 
 marched and counter-marched every way as the queen was laid. 
 The Doctor persevered in these experiments, till, after five days 
 and nights of voluntary fasting, they all died of inanition except 
 the queen, and she survived her faithful subjects only a few 
 hours. 
 
 This remarkable attachment between queen and subjects appears 
 to be reciprocal the sovereign being as strongly sensible of it as 
 
THE PRINCESS ROYAL. 
 
 those over whom she rules. Though offered honey on several 
 oecasions during her temporary separation from tlie swarm in 
 these experiments, she constantly refused it, disdaining a life 
 which was no life to her, deprived of the society of iier faithful 
 people.* 
 
 136. After the departure of her majesty there seems to be a sort 
 of interregnum in the hive during the succession of swarms. No 
 new sovereign is for the moment elevated to the throne. A strong 
 guard is established at each of the royal cells, whose duty it is- 
 to confine the princesses with the utmost rigour to their respective 
 cells, carefully feeding them, and only liberating them at intervals 
 of some days according to the successive departure of the swarms. 
 They are liberated in the strict order of their seniority, the 
 nymph proceeding from the first royal egg, or the princess royal, 
 being invariably the first set free. 
 
 137. When she issues forth, her first impulse, like that of all 
 queens, is to fall upon the cells containing her younger sisters to 
 destroy them. This, which in other states of the colony is permitted 
 by the workers, is now strenuously and eftectually opposed by them. 
 When she approaches the neighbourhood of the royal cells, the 
 guard in whose charge these are placed, pinch, worry, and hunt 
 her until they compel her to depart, but never attemjjt to assail 
 her with their stings or seriously injure or disable her. 
 
 Now, as there are usually a great number of these royal cells in 
 difterent parts of the hive, our princess finds it a difficult matter 
 to obtain any corner where she can remain unmolested. Inces- 
 santly impelled by her instinct to attack the cells of her sisters, 
 and as incessantly repulsed from them by the surrounding guard, 
 her life is rendered miserable. She is in a constant state of 
 agitation, running from one group of workers to another, until at 
 length the agitation is shared by a certain portion of the workers 
 themselves. When this occurs, a crowd of bees are seen rushing 
 towards the portals of the city. They issue from it accompanied 
 by their young and virgin queen. It is the second swarm of the 
 season, 'and differs from the first only in the age and condition of 
 its sovereign. 
 
 138. Alter this emigration the workers, who have remained in 
 possession of the hive liberate another of the princesses, the 
 second in seniority, whom they treat exactly in the same manner 
 as the former. The same succession of repulses by the guards of 
 the remaining royal cells takes place, attended by like consequences, 
 this second princess leading forth in the same manner the third 
 swarm, and so on. 
 
 139. This spectacle is repeated three or four times in the season 
 
 * Bevan, p. 148. 
 
 69 
 
THE BEE. 
 
 in a well-peopled hive, until tlie population is so reduced that the^ 
 number necessary to form a sufficient guard upon the royal cells- 
 can no longer be spared from the general industry of the hive. 
 Several princesses then escape from the cells, nearly at the same 
 time, who fall upon each other in the manner already described, 
 being now encouraged instead of being opposed by the workers. 
 In fine, all but one fall in those combats, and this fortunate 
 survivor, who is in general the eldest of the princesses remaining 
 in the hive, ascends the throne, and is acknowledged by the whole 
 community. 
 
 According to Huber, swarms issue from the hive only in sun- 
 shine and a calm atmosphere. After all the precursors of a 
 swarm have appeared, a passing cloud often arrests it, and the 
 intention of the bees seems to be abandoned. An hour later the 
 appearance of the bright sun will reproduce all the usual move- 
 ments, and the swarm wiU issue. 
 
 Many conjectures are made as to the means by which the 
 workers know so well, as they undoubtedly do, the relative ages 
 of the several princesses, so as to liberate them according to 
 seniority. Huber conjectures that a peculiar sound, which they 
 produce before their liberation from the cells, and which he 
 thought varied in loudness and pitch, might be the distinguishing 
 character of relative age. 
 
 140. A contingency arises occasionally in the bee community, 
 which we have not yet noticed, and which is attended with conse- 
 quences of a very curious and interesting nature. It was dis- 
 covered by Schirach, and confirmed by numerous and long continued 
 observations of Huber, that when by any cause a colony loses it& 
 queen, without having any royal cells or royal eggs previously 
 provided, they are enabled by certain extraordinary processes and 
 expedients to produce princesses, among whom they may obtain a 
 successor to their last sovereign. 
 
 M. Schirach, Secretary of an Apiarian society, at Little 
 Bautzen in upper Lusatia, observed that bees, when shut up with 
 a portion of comb containing worker brood only, would soon con- 
 struct royal ceUs, into which they would put worker eggs, the 
 grubs from which, being nourished with royal jelly, would grow 
 up as queens. This remarkable result is known among apiculturers 
 as the Lusatian experiment. This experiment has since been 
 repeated thousands of times, and always with the same results by 
 all the most eminent naturalists who have directed their 
 researches to this part of entomology, and indeed generally by 
 all bee cultivators. So that of the fact itseK, strange and 
 incredible as it may seem, there is not the faintest shadow of 
 doubt. 
 70 
 
FACTITIOUS QUEENS. 
 
 The following is the process by which this miracle of nature is 
 performed. 
 
 Having chosen a worker grub, from one to three days old, the 
 workers pull down two of the cells adjacent to that in which the 
 chosen grub lies. They pull down the walls which separate 
 these three chambers, so as to throw them into one three times 
 more spacious than the single cell of the grub. Leaving the 
 pyramidal bases of these three cells untouched, they construct 
 around the grub a large cylindrical tube, which is consequently 
 included within the remaining walls of the three demolished cells, 
 the axis of the tube being parallel to that of the cells, and there- 
 fore horizontal. 
 
 It seems, however, that to accomplish the desired change on 
 the nature of the grub, it is not only necessary to give it an 
 enlarged cell, but one of which the axis is vertical instead of 
 being horizontal. On the third day, therefore, from the comr 
 mencement of their operations, they take measures to cement to 
 the horizontal tube a vertical chamber having a conical form, 
 making with the horizontal tube an elbow. To accomplish this 
 they gnaw away several cells below the end of the tube, sacrificing 
 without mercy the grubs which occupy these, as well as those 
 which occupied the two cells adjacent to the original cell of the 
 chosen grub. 
 
 This rectangular cell, therefore, composed of the original 
 cylindrical, and the more recently constructed conical cell, may 
 be considered as having some such form as here roughly sketched, 
 
 -A- B 
 
 Fig. 53. 
 
 (fig. 53,) where abcd is the horizontal cylindrical part formerly 
 filled by three worker hexagonal cells, and sped, the vertical 
 conical part, subsequently cemented to it, and built with the wax 
 obtained from the demolition of the worker cells under abcd. 
 
 During two days which the grub inhabits this vertical cell, 
 B F D E, a nurse may always be observed with its head plunged 
 
 71 
 
THE BEE. 
 
 into it, and when one quits it another takes its place, thus 
 relieving each other with all the regularity of military sentinels. 
 These bees keep constantly lenthening the cell, bfed, as the 
 grub grows older, and duly supply it with food, which they place 
 before its mouth and round its body. The animal, which can 
 only move in a spiral direction, keeps turning to take the jelly 
 deposited before it, and thus slowly working downwards, arrives 
 insensibly nearer the orifice of the cell, just at the time that it 
 is ready to be metamorphosed into a nymph. At this moment, 
 the workers, conscious of the impending change, seal up the 
 mouth E F of the cell, and cease their attentions, leaving nature 
 to effect the last transformation. 
 
 One of these cells is shown at d, in fig. 49. 
 
 That the mere change in the quality of the food, combined with 
 the increased capacity and altered form of the cradle, should be 
 the means of producing a transformation, so extreme as that from 
 a worker to a queen, must be a matter of profound astonishment 
 to every reflecting mind ; so much so indeed, that without the 
 most incontestable evidence, and the power moreover of repro- 
 ducing the phenomenon at will, it could not be credited. Let 
 any one imagine how such an assertion as this, that the foal of 
 an ass by a particular sort of provender, and by being reared in 
 a stable of particular magnitude and form, could be made to grow 
 into a through bred horse, would be received. Yet, such a trans- 
 formation produced by such means would not be one whit more 
 wonderful than the change of a worker grub into a queen-bee, 
 by the means just stated. " What ! " says Kirby, addressing his 
 correspondent, you will ask, can a larger and warmer house, 
 a different and more pungent food, and a vertical instead of an 
 horizontal posture, give a bee a different-shaped tongue and 
 mandibles ; render the surface of its under-legs flat instead of 
 concave ; deprive them of the fringe of hairs that forms the basket 
 for carrying the masses of pollen, — of the auricle and pecten which 
 enable the workers to use these legs or feet as pincers, — of the brush 
 that lines the insides of the feet ? Can they lengthen its abdomen; 
 alter its colour and clothing ; give a curvature to its sting ; 
 deprive it of its wax pockets ; and of the vessels for secreting that 
 substance ; and render its ovaries more conspicuous and capable 
 of yielding worker and drone eggs ? " 
 
 In the next place, can the apparently trivial circumstances just 
 mentioned alter altogether the instincts of these creatures ? Can 
 they give to one description of animals address and industry, and 
 to the other astonishing fecundity ? Can we conceive them to 
 change their very passions, tempers, and manners ? That the 
 very same foetus, if fed with more pungent food, in a higher 
 
 *72 
 
COMBAT OF FACTITIOUS QUEENS. 
 
 temperature, and in a vertical position, shall become a female, 
 destined to enjoy love, to burn with jealousy and an^er, to be 
 incited to veageance, and to pass her time without labour — that 
 this very same foetus, if fed with more simple food, in a lower 
 temperature, in a more confined and horizontal habitation, shall 
 come forth a worker, zealous for the good of the community, a 
 defender of the public rights, enjoying an immunity from the 
 stimulus of sexual appetite and the pains of parturition — laborious, 
 industrious, patient, ingenious, skilful, — incessantly engaged in 
 the nurture of the young, in collecting honey and pollen ; in 
 elaborating wax ; in constructing cells, and the like ; paying the 
 most respectful and assiduous attention to objects which, had 
 its ovaries been developed, it would have hated and pursued 
 with the most vindictive fury until it had destroyed them ! 
 Further, that these factitious queens, thus produced from worker 
 eggs treated as above described, shall differ remarkably from the 
 natural queens proceeding from royal eggs in being altogether 
 mute ! All this must seem so improbable, and next to impossible, 
 that it would require the strongest and most irrefragable evidence 
 to establish it.* 
 
 141. It will be remembered that the princesses, when forcibly 
 confined to their native cells by the workers on guard over them, 
 after they have undergone the last transformation, utter a peculiar 
 sound, to the varieties of which Huber ascribes the power of the 
 workers to determine their relative ages. Kirby in the observa- 
 tions just quoted, refers to this, when he indicates one of the 
 distinctions between the factitious and natural queens, the former 
 never uttering these or any other sounds. 
 
 142. Another remarkable distinction between the factitious and 
 natural queens is indicated by Huber ; no guard is kept at the 
 doors of the cells of factitious princesses, like that which has been, 
 already described in the case of the cells of natural princesses. 
 The factitious princesses, unlike the natural, are not detained in 
 their cells after they have undergone the last transformation, but 
 are allowed to issue forth, if they have not been already destroyed 
 by the jealous rage of the first which comes to life. 
 
 This peculiarity in the policy of the hive may be explained by 
 the fact, that while the natural princesses are wanted to take the 
 sovereignties of the successive swarms, the factitious ones are only 
 produced to meet the extraordinary emergency of the hive being 
 deprived of its queen, leaving behind her no royal brood, and 
 since only one queen is wanted, the factitious princesses are 
 allowed, and indeed encouraged, by the workers to engage in 
 
 * Kirby, Int., vol. ii. 110. 
 
 7a 
 
THE BEE. 
 
 martial conflict until one only survives, who assumes the throne 
 of the hive. 
 
 143. The circumstances and anecdotes related by observers 
 illustrative of the affection, devotion, and respect manifested 
 towards the queen by her subjects are innumerable. In addition 
 to those which we have already given, the following will be 
 read with interest. 
 
 All the devotion, it must be observed, commences only after the 
 royal nuptials. A virgin queen is treated with indifference the 
 most absolute. But after her marriage has been celebrated, and 
 she presents herself to her subjects in the double character of 
 sovereign and mother, they more than respect her. " They are," 
 says Reaumur,* ''constantly on the watch to make themselves 
 useful to her, and to render her every kind office. They are for 
 ever offering her honey. They lick her with their proboscis, and 
 wherever she goes she has a court to attend her." 
 
 144. The same naturalist relates that even the inanimate body of 
 the queen is an object of tenderness and affection to the bees. He 
 took one out of the water quite motionless and seemingly dead. 
 It was also mutilated, having lost part of one of its legs. Bring- 
 ing it home, he placed it among some workers that he had found 
 in the same situation, most of which he had recovered by means 
 of warmth, some, however, being still in as bad a state as the 
 poor queen. No sooner did these revived workers perceive the 
 latter in this wretched condition than they appeared to compas- 
 sionate her case, and did not cease to lick her with their tongues till 
 she showed signs of returning animation ; which the bees no sooner 
 perceived than they set up a general hum as if for joy at the 
 happy event. All this time they paid no attention to the workers, 
 who were in a most miserable condition, f 
 
 145. In the economy of the bee, there is nothing which presents, 
 more difficulty to the naturalist than the satisfactory explanation 
 of the functions of the drones. These, as has been already ex- 
 plained, are the sole male members of the society ; the queen 
 being the sole fertile female ; and the workers, though female,, 
 exercising none of the functions of that sex, and being limited to 
 the industrial and parental duties of the society. The number of 
 drones in a single society is from 1500 to 2000, one only of whom- 
 can enjoy the honour of elevation to the distinguished position of 
 king consort, and that one, as already explained, never surviving 
 the day of the nuptials. What then, it may well be asked, are 
 the services rendered to the community by these hundreds of con- 
 sumers of the products of the industry of the society ? They never 
 themselves take part in the common labours. They neither 
 
 * Reaumur, v. 262. t Reaumur, v. 265. 
 
 74 
 
MASSACRE OF DRONES. 
 
 collect food nor materials, nor do they aid in any way in the con- 
 struction of the dwellings, nor in the care or nurture of the 
 young. In the absence of any better explanation of their vast 
 number it has been said that the purpose is to insure a consort, 
 to the queen. But surely this object might be effected without 
 encumbering the society with 2000 candidates for the royal 
 favour. 
 
 It has been suggested by some apiarists that the drones may 
 sit upon the eggs, and by others that their use may be to develope 
 heat sufficient to maintain the hive at the necessary temperature ;. 
 but the experiments and observations of other naturalists have set 
 aside these hypotheses. 
 
 146. Whatever be the purpose which this section of the society is 
 destined to fulfil, their treatment by the people, and the manner 
 in which their existence is terminated, are remarkable. 
 
 So long as swarms continue to issue from the hive, drones are 
 wanted to supply the necessary proportion of that class to accom- 
 pany them. But after the swarming season closes, which in these 
 climates it generally does towards the end of July, at least in dry, 
 summers, the general massacre of the drones takes place. At that 
 time the bees are seen hunting them in all parts of the hive, and: 
 driving them to the base upon which it stands. Soon after this- 
 the stand and the ground before the hive are found to be covered 
 with the bodies of hundreds of the murdered drones. It was 
 supposed by Bonnet that no direct massacre was executed, but 
 that the drones driven from the stores of their food died of 
 starvation.* 
 
 147. Huber, however, among his other numerous discoveries,> 
 contrived to witness, through the eyes of his faithful Burnens. 
 the actual massacre. 
 
 At the season at which the extermination usually took place, 
 he placed upon plates of glass six populous hives occupied by 
 swarms of the preceding year, and Burnens lying on his back 
 under the hives was enabled to witness all that took place by the 
 transparency of their bases. On the 4th of July, 1787, he wit- 
 nessed the massacre, which took place at the same hour in aU the 
 six hives. The base was crowded with bees, who appeared in a 
 state of great excitement. As fast as the drones, hunted by 
 other bees from the superior parts of the combs, arrived at the 
 base, the bees there assembled fell upon them, seizing them by 
 their antennse, legs, or wings, and after dragging them about with 
 apparent rage, put them to death by stabbing them with their 
 stings between the segments of the abdomen. The moment they 
 were thus pierced, they spread their wings and expired. However, , 
 * Bonnet, "Contemplation de la Nature," chap. xxvi. part. xi. 
 
THE BEE. 
 
 as if the workers did not feel sufficiently certain of their fate, 
 they continued to pierce their bodies with their stings, and often 
 drove these formidable weapons in so deep that they could 
 only extricate them by unscrewing them in the manner already 
 described (126). 
 
 The next day they resumed their observations, when a most 
 curious spectacle presented itself. During three hours they saw 
 the massacre of drones, which had been resumed with the same 
 fury, continued. On the preceding day they had exterminated 
 all the drones of their own hives ; but this time their attack was 
 directed against those of neighbouring hives, which, having fled, 
 had taken refuge in these, after the massacre of the preceding day 
 had been concluded. 
 
 Not content with this complete extermination of the drones 
 themselves, the workers resorted to the cells in which drone 
 nymphs were contained, which had not yet completed their final 
 transformation. These they pitilessly dragged forth, killed, 
 sucked the juices contained in their bodies, and then flung the 
 carcasses out of the hives. 
 
 148. It was also ascertained by Huber, that in hives deprived of 
 their queen, or in which the queen, by reason of retarded fecunda- 
 tion, only laid drone eggs, no massacre ever took place. In such 
 hives the drones not only find a sure refuge, but are carefully 
 nurtured and fed. 
 
 This circumstance, combined with the fact that the massacre 
 never takes place until after the swarming season is over, seems to 
 indicate the functions of the drones. They are useful only where 
 candidates for the royal nuptials are likely to be wanted. 
 
 149. The most interesting class of the bee community is also that 
 which is by far the most numerous, the workers. Indeed, to this 
 class all others must be regarded as subordinate, just as in human 
 societies all are dependent on the producing classes. Much 
 respecting their character, habits, and manners, in relation to 
 the care of their young, and the construction of the city, in a 
 word in respect to their internal labours, has been already 
 explained. Something now must be said of their external 
 industry, directed to the collection of provisions for the com- 
 munity, young and old, and of the materials necessary for the 
 prosecution of all their various works, labours which have been 
 illustrated by Professor Smyth in the following beautiful lines; — 
 
 ** Thou cheerful bee ! come, freely come, 
 And travel round my woodbine bower ; 
 Delight me with thy wandering hum, 
 Ahd rouse me from my musing hour. 
 
 76 
 
CHAEAC.TER OF WORKERS. 
 
 Oh ! try no more those tedious fields, 
 Come taste the sweets my garden yields ; 
 The treasures of each blooming mine, 
 The bud, the blossom — ^all are thine. 
 
 And, careless of this noontide heat, 
 I'll fbllow as thy ramble guides ; 
 To watch thee pause and chafe thy feet, 
 And sweep them o'er thy downy sides ; 
 Then in a flower's bell nestling lie, 
 And all thy envied ardour ply ! 
 And o'er the stem, though fair it grow, 
 With touch rejecting, glance and go. 
 
 " Oh, Nature kind ! Oh, labourer wise ! 
 That roam'st along the summer's ray. 
 Glean' st every bliss thy life supplies. 
 And meet'st prepared thy winter day ! 
 Gro, envied, go — with crowded gates 
 The hive thy rich return awaits ; 
 Bear home thy store, in triumph gay, 
 And shame each idler of the day." 
 
 150. The immediate objects to which the exterior industry of 
 the bee is directed, are nectar, pollen, and propolis. 
 
 Nectar is a specific juice, found in certain classed of flowers, 
 from which the bee elaborates honey and wax. 
 
 Pollen is a peculiar powder, or dust, spread over the anthers of 
 flowers, which constitutes the principle of fecundation of the 
 flowers themselves, and is the material of which the bee makes 
 bread, which serves as food both for old and young. 
 
 Propolis is a i-esinous substance, evolved by certain vegetables 
 which the bee uses as cement, mortar, or glue, in its architecture. 
 "When the bee pierces the vessels of the flowers, which, containing 
 nectar, are called nectarines, and swallows that precious juice, it 
 is deposited provisionally in the honey-bag already described 
 (26) ; sometimes called, on that account, the first stomach. Here 
 this nectar is converted into honey, the chief part of which is 
 regurgitated, to be stored up for future general consumption in the 
 honey-cells of the combs. 
 
 In the stomach, properly so called (26), and in the intestines, 
 the bread only is found. 
 
 How the wax is secreted, physiologists have not yet discovered 
 with any certainty. It is evident, however, that the immediate 
 seat of its production is within the abdomen, since the parts called 
 wax- pockets, from which it is externally evolved, are rendered 
 visible by pressing the abdomen so as to make it extend itself. A 
 pair of quadrangular whitish pockets, of soft membranaceous 
 textui'e, will then be seen on each of the four middle ventral, 
 
 77 
 
THE BEE. 
 
 segments. On these the plates of wax are formed, and are found 
 upon them in different states so as to he more or less perceptible. 
 
 151. Observe a bee, says Kirby, that has alighted on a flower. 
 The hum produced by the motions of her wings ceases, 
 and her work begins. In an instant she unfolds her tongue, 
 which was previously rolled up under her head. With what 
 rapidity does she dart this organ between the petals and the 
 stamina! At one time she extends it to its full length, then she 
 contracts it ; she moves it about in all directions, so that it may 
 be applied to the concave and convex surface of the petal, and 
 sweep them both, and thus by a virtuous theft, she robs it of all 
 its nectar. All the while this is going ou, she keeps herself in a 
 state of constant vibratory motion. 
 
 Flowers, though the chief, are not the only sources from which 
 the bee derives the material of honey and wax. She will also eat 
 sugar in every form, treacle, the juice secreted by aphides ; and, 
 in fine, the juice of the bodies of nymphs and of eggs of bees 
 themselves, as already explained. 
 
 152. When the industrious little creature has filled its honey- 
 bag with nectar, it proceeds to collect the pollen, of which it 
 robs the flowers by brushing it off with the feathery hairs with 
 which its body is covered. As the honey is called the nectae, so 
 this pollen, or the substance bee-bread, into which it is converted, 
 may be called the ambeosia. of the hive. Together they con- 
 stitute the food and the drink of the population. 
 
 When the bee has so rolled itself in this farina of the blossoms 
 of the garden and the field, that its whole body is so powdered 
 with it, as to give it the peculiar colour of the species of flowers 
 to which it happens to resort, it suspends its excursions, and sets 
 about to brush its body with its legs, which, as already explained, are 
 supplied with brushes for this express purpose. Every particle of 
 the flower thus brushed off is most carefully collected and kneaded 
 up into two little masses, which are transferred from the fore to 
 'the hind legs, and there packed up into the baskets provided for 
 its reception and transportation. 
 
 Naturalists generally are of opinion that in each of its excur- 
 sions a bee confines its foraging operations to a single species 
 of flower. This explains the fact that the colour of their load 
 after such excursions is uniform, depending on the particular 
 species of flower which they have robbed of its sweets. Thus, 
 according to Reaumur, some bees are observed to return loaded 
 with red pellets on their thighs, others with yellow, others 
 whitish, and others with green. 
 
 Kirby observes, that it seems probable that the bee confines its 
 operations in such excursions to flowers of the same species, and 
 78 
 
MAKRIAGE OF FLOWERS. 
 
 tliat the grains of pollen which enter into the same mass should 
 he homogeneous, and consequently fitted hy their physical pro- 
 perties to cohere with greater facility and firmness. 
 
 153. But connected with this, another important purpose of 
 ■nature is fulfilled, which must not here pass without special notice. 
 The principle, so fruitful in important social consequences among 
 animals, that the ofi'spring owes its parentage jointly to two 
 individuals of difierent sexes, or, in other words, must always 
 have a father and a mother, equally prevails in the vegetahle 
 kingdom. There also are the gentlemen and ladies, there also 
 are the loves which unite them, loves which as well as those of 
 superior orders of beings have supplied a theme for poets.* Now 
 among the many other interesting offices with which the Author 
 of nature has invested the little creatures, which form the subject 
 of this notice, not the least singular is that of being the priests 
 who celebrate the nuptials of the flowers. It is the bee literally 
 which joins the hands and consecrates the union of the fair virgin 
 lUy and the blushing maiden rose with their respective bride- 
 grooms. The grains of pollen which we have been describing are 
 these brides and bridegrooms, and are transported on the bee 
 from the male to the female flower ; the happy individuals thus 
 united in the bands of wedlock being the particular grains, which 
 the bee lets fall from its body on the flower of the opposite sex, as 
 it passes through its blossom. 
 
 154. And here we find another circumstance to excite our admi- 
 ration of the wise laws of that Providence, which cares for the well- 
 heing of a little flower, as much as for that of a great lord of the 
 ■creation. If the bee wandered indifferently from flower to flower 
 without selection, the gentlemen of one species would be mated 
 with the ladies of another, hybrid breeds would ensue, and the 
 ■confusion of species would be the consequence. But the bee, as 
 knowing this, flies from rose to rose, or from lily to lily, but never 
 i'rom the lily to the rose, or from the rose to the lily. 
 
 155. When a bee, laden with pollen, arrives in the hive, she some- 
 times stops at the entrance, and leisurely detaching it piecemeal 
 from her legs, devours it bit by bit. Sometimes she passes into 
 the hive and walks over the combs, or stands stationary upon 
 .them, but whether moving or standing never ceases flapping her 
 wings. The noise thus produced, a sort of buzzing, seems to be 
 a call understood by the populace within hearing, for three or four 
 of them immediately approach and surround her. They begin 
 to aid her to disembarrass herself of her load, each taking and 
 swallowing more or less of her ambrosia until the whole is 
 ^disposed of. 
 
 * Darwin's Loves of the Plants. 
 
 79 
 
THE BEE, 
 
 156. When more pollen has been collected than the society wants 
 for present use, it is stored up in some of the unoccupied cells. The 
 bee, laden with it, puts her two hind legs into the cell, and with 
 the intermediate pair pushes off the pellets. When this is done 
 she, or another bee if she be too much fatigued, enters the cell 
 head-foremost and remains there for some time, during which she 
 is occupied in diluting, kneading, and packing the bee-bread ; and 
 so they proceed one after another, until the cell has been well 
 packed and filled with the store of provisions. In some combs a 
 large portion of the cells is filled with this ambrosia, in others, 
 cells containing it are intermixed with those filled with honey or 
 with bread. It is thus everywhere at hand for use.* 
 
 The propolis, the third object of bee industry, is collected from 
 various trees, and especially from certain species of the poplar. 
 It is soit and red, will allow of being drawn out into a thread, is 
 aromatic, and imparts a gold-colour to white polished metals. It 
 is employed in the hive, as already stated, not only in finishing 
 the combs, but also in stopping up every chink and orifice by 
 which cold, wet, or any enemy could enter. They coat with it the 
 chief part of the inner surface of the hive, including that of the 
 sticks placed there for the support of the comb. It is carried by 
 the bees in the same manner as is the pollen on the hind legs. 
 
 157. The radius around their habitation, within which the bee 
 industry is confined, is differently estimated, being according to 
 some a mile, and according to others extending to a mile and a 
 half. Various experiments prove that it is by their scent that 
 the bees are guided to the localities where their favourite flowers 
 abound. 
 
 * Khby, Int., ii. 151. 
 
 8i 
 
Fig. 64.— Radouan's 
 hive. 
 
 THE BEE. 
 CHAPTBE VI. 
 
 158. How^ they fly straight back to the hive — manner of discovering the 
 nests of wild bees in New England. — 159. Average number of daily ex- 
 carsions. — 160. Bee pasturage — transported to follow it — in Egypt and 
 Glreece. — 161. Neatness of the bee. — 162. Its enemies. — 163. Death's- 
 head moth. — 164. Measures of defence adopted by Huber. — 165. Mea- 
 sures adopted bythe bees. — 166. Wars between different hives. — 167. 
 Demolition of the defensive works when not needed. — 168. Senses of 
 insects. — 169. Senses of the bee. — 170. Smell. — 171. Experiments 
 of Huber. — 172. Remarkable tenacity of memory. — 173. Experi- 
 ments to ascertain the organ of smell. — 174. Repugnancy of the bee 
 for its own poison. — 175. Their method of ventilating the hive. — 
 176. Their antipathy against certain persons. — 177. Against red and 
 black -haired persons. — 178. Difference of opinion as to the functions 
 of the antennae. — 179. Organs of taste. — 180. Hearing: curious anec- 
 dotes. — 181. Vision. — 182. Peculiar characters of queens ; royal old 
 maid. — 183, Drone-bearing queens. — 184. Change of their instincts and 
 manners. — 185. Their treatment by the workers. — 186. Nuptials never 
 celebrated in the hive. — 187. Effect of amputating the royal antennae. 
 
 i58. One of the many wonders presented by their economy is the 
 directness and unerring certainty of their flight. While collecting 
 their sweets they fly hither and thither, forward or backward, and 
 right or left, as this or that blossom attracts them ; but when 
 fully laden with the spoil, though upwards of a mile from their city, 
 they start for it in a course more exact than if they were guided 
 Lardner's Museum of Science. o 81 
 
 No. 127. 
 
THE BEE. 
 
 by a rudder and compass, governed by the hand of the most con- 
 summate navigator. By what means this is accomplished has 
 never been explained, but connected with it is an account given 
 in the Philosophical Transactions " which we cannot refrain from 
 quoting here. ''In New England a species of wild hive-bees 
 abounded in the forests about the year 1720. The following was 
 the method practised for discovering their nests and obtaining 
 their honey. The honey-hunters set a plate containing honey or 
 sugar, upon the ground on a clear day. The bees soon discovered 
 and attacked it. Having captured two or three who had thus 
 gorged themselves, the hunter liberated one of them and marked 
 the direction in which it flew. He then changed his position, 
 walking in a direction at right angles to the course of the bee to 
 a distance of a few hundred feet, where he liberated another of 
 his little captives, and noted as before the direction of its flight. 
 The point where the two directions thus obtained, intersected, was 
 of course that to which both bees had directed their course, and 
 there the nest was always found." 
 
 159. The industry of the bee may be estimated by the average 
 number of its daily excursions from the hive to collect provisions. 
 According to Reaumur, if the total number of excursions be 
 divided by the total number of bees in a hive, the average number 
 daily made by each bee would be from five to six. But as one- 
 half of the bees are occupied exclusively with the domestic busi- 
 ness of the society, either in nursing and tending the young, 
 packing and storing the provisions, or constructing the combs, 
 the total number of excursions must be divided, not between the 
 whole, but between only half the total number of bees, which 
 would give ten excursions to each individual of the collecting 
 class ; and if the average length of each excursion be taken at 
 three quarters of a mile, this would give the average distance 
 travelled by each collector as fifteen miles ! It is estimated by 
 Kirby that the quantity of ponderable matter thus transported 
 during a season in a single hive would be about 100 lbs. '' What 
 a wonderful idea does this give of the industry and activity of 
 those useful little creatures ! and what a lesson do they read to 
 the members of societies, that have both reason and religion to 
 guide their exertions for the common good! Adorable is that 
 Great Being who has gifted them with instincts which render 
 them as instructive to us, if we will condescend to listen to them, 
 as they are profitable." * 
 
 160. The plants and flowers which form the pasturage of the 
 bees are, in many countries, produced at diff'erent places at different 
 seasons of the year ; and where the bees in a particular neigh- 
 
 * Kirby, Int., ii. 155. 
 
 82 
 
TRANSPORT OF BEES. 
 
 bourhood are numerous, the pasturage surrounding their hives 
 often becomes exhausted. In such cases the agriculturists trans- 
 port the bees from localities which they have exhausted, to others 
 in a state of comparative abundance, just as the shepherd drives 
 his sheep from field to field, according as the pasturage is eaten 
 down. In Egypt, towards the end of October, when the inunda- 
 tions of the Nile have ceased, and the husbandmen can sow the 
 land, saintfoin is one of the first things sown ; and as Upper is 
 warmer than Lower Egypt, the saintfoin gets there first into 
 flower. At this time bee-hives are transported in boats from all 
 parts of Egypt into the upper district, and are there heaped in 
 pyramids upon the boats prepared to receive them, each being 
 marked with a number which indicates its owner. In this station 
 they remain for some days, and when it is considered that they 
 have pretty well exhausted the surrounding fields of their sweets, 
 they are removed a few leagues lower down, where they are 
 retained for a like interval; and so they descend the river, until 
 towards the middle of February they arrive at its mouth, where 
 they are distributed among their respective proprietors.* 
 
 A similar practice prevails in various parts of the East and 
 in Greece. The inhabitants of the towns are often the proprietors 
 of fifty or sixty hives, the product of which forms an article of 
 their trade. The hives are sent in the season when the herbage 
 is in flower to the various rural districts, being sealed up by the 
 owner, the small bee-door only being open, and are given in 
 charge to the villagers, who at the close of the season are paid for 
 their care of them. Ranges, consisting of five or six hundred 
 hives, are often seen thus put out to grass.f 
 
 161. Bees are remarkable for neatness and cleanliness, both as to 
 their habitations and their persons. They remove all dirt and 
 nuisances from their hive, with the regularity of the neatest 
 housewives. When their strength is insufScient for this, they 
 contrive various ingenious expedients to abate the nuisance. If 
 snaUs find their way into the hive, as they sometimes do, they 
 kill them with their stings ; and in order to prevent noisome and 
 unwholesome effluvia from their decomposing remains, they 
 embalm them with propolis. If the snail is protected from their 
 stings by its shell, they bury it alive in a mass of propolis. 
 
 When pressed by natural wants, they do not defile their habita- 
 tion by relieving themselves in it, but go abroad for the purpose. 
 
 When a young bee issues from the cell, a worker immediately 
 approaches, and, taking out its envelope, carries it out of the 
 hive ; another removes the exuviae of the larva, and a third any 
 
 * Reaumur, t. 698. 
 t "Willock, in "Gardeners' Chronicle, 1841, p. 84. 
 
 G 2 83 
 
THE BEE. 
 
 filth, or ordure that may remain, or any pieces of wax that may 
 have fallen in when the young bee broke through its cocoon. But 
 they never attempt to remove the silk lining of the cell spun by 
 the larva in its first transformation, because that, instead of being 
 a nuisance, gives increased solidity and ornament to the cell. 
 
 162. Notwithstanding the amiable character and excellent poli- 
 tical organisation of the bees, these little people have numerous 
 enemies, with some of whom they are often compelled to wage 
 offensive wars, and against others to fortify themselves, by expe- 
 dients and with skill, which will bear comparison with the opera- 
 tions of the most consummate military engineers. Sebastopol itself 
 was not more ingeniously defended by its outworks than, in certain 
 cases, bee-hives are. 
 
 From the curious account which Latreille has given us of 
 Philanthus aviporus, a wasp-like insect, it appears that great havoc 
 is made by it of the unsuspecting workers, which it seizes while 
 intent upon their daily labours, and carries off to feed its young. 
 
 163. Another insect, which one would not have suspected of 
 marauding propensities, must here be introduced. Kuhn informs 
 us, that long ago (in 1799) some monks who kept bees, observing 
 that they made an unusual noise, lifted up the hive, when an 
 animal fiew out, which, to their great surprise, no doubt, for they 
 at first took it for a bat, proved to be the death's-head hawk-moth 
 {Acherontia atropos), already celebrated as the innocent cause of 
 alarm ; and he remembers that several, some years before, had been 
 found dead in the bee-houses. M. Huber also, in 1804, discovered 
 that it had made its way into his hives and those of his vicinity, 
 and had robbed them of their honey. In Africa, we are told, it 
 has the same propensity ; which the Hottentots observing, in 
 order to monopolise the honey of the wild bees, have persuaded 
 the colonists that it infiicts a mortal wound. 
 
 This moth has the faculty of emitting a remarkable sound, 
 which he supposes may produce an effect upon the bees of a hive, 
 somewhat similar to that caused by the voice of their queen, 
 which as soon as uttered strikes them motionless, and thus it may 
 be enabled to commit with impunity such devastation in the midst 
 of myriads of armed bands. 
 
 The larvae of two species of moth ( Galleria cereana and Mello- 
 nella) exhibit equal hardihood with equal impunity. They, 
 indeed, pass the whole of their initiatory state in the midst of 
 combs. Yet, in spite of the sting of the bees of a whole republic, 
 they continue their depredations unmolested, sheltering themselves 
 in tubes made of grains of wax, and lined with silken tapestry, 
 spun and woven by themselves, which the bees (however disposed 
 they may be to revenge the mischief which they do to them, by 
 U 
 
ENEMIES OF BEES. 
 
 devouring what to all other animals would be indigestible — their 
 wax) are unable to penetrate. These larvse are sometimes sc 
 numerous in a hive, and commit such extensive ravages, as to 
 force the poor bees to desert it and seek another habitation." * 
 
 164. Huber gives the following most interesting account of 
 the measures taken by his bees, to fortify themselves against the 
 incursions of the death's-head moth. 
 
 When he found his hives attacked and their store of honey 
 pillaged by these depredators, he contracted the opening left for 
 the exit and entrance of the bees to such an extent, as while it 
 allowed them free ingress and egress, it was so small that their 
 plunderers could not pass through it. This was found to be per- 
 fectly effectual, and all pillage was thenceforward discontinued 
 in the hives thus protected. 
 
 165. But it happened that in some of the hives this precaution 
 was not adopted, and here the most wonderful proceeding on the 
 part of the bees took place. Human contrivance was brought into 
 immediate juxtaposition with apiarian ingenuity. 
 
 The bees of the undefended hives raised a wall across the gate 
 of their city, consisting of a stiff cement made of wax and propolis 
 mixed in a certain proportion. This wall, sometimes carried 
 directly across and sometimes a little behind the door, first com- 
 pletely closed up the entrance ; but they pierced in it some 
 openings just large enough to allow two bees to pass each other in 
 their exits and entrances. 
 
 The little engineers did not follow one invariable plan in these 
 defensive works, but modified them according to circumstances. 
 In some cases a single wall, having small wickets worked through, 
 it at certain points, was constructed. In others several walls were 
 erected one within the other, placed parallel to each other, with 
 trenches between them wide enough to allow two bees to pass 
 each other. In each of these parallel w^Us several openings or 
 wickets were pierced, but so placed as not to correspond in posi- 
 tion, so that in entering a bee would have to follow a zigzag 
 course in passing from wicket to wicket. In some cases these 
 waUs or curtains were wrought into a series of arcades, but so 
 that the intervening columns of one corresponded to the arcades of 
 the other. 
 
 The bees never constructed these works of defence without 
 urgent necessity. Thus, in seasons or in localities where the 
 death's-head moth did not prevail, no such expedients were 
 resorted to. Nor were they used against enemies which were 
 open to attack by their sting. The bee, therefore, understands 
 
 * Kirby, vol. i. p. 130. 
 
 85 
 
THE BEE. 
 
 not merely the art of offensive war, and can play the part of the 
 common soldier, but is also a consummate military engineer; 
 and it is not against the death's-head moth alo.ne that it shows 
 itself capable of erecting such defences. 
 
 166. Thinly peopled hives are sometimes attacked by the popu- 
 lation of other bee cities. In such cases, incapable of immediate 
 defence by reason of their inferior numbers, they erect similar 
 fortifications, but in this case they make the wickets in the walls 
 so small that a single worker only can pass through them ; and a 
 small number stationed on the inside of these openings, are accord- 
 ingly sufiicient to defend the hive against the attack of large 
 besieging armies. 
 
 167. But when the season for swarming arrived, these works of 
 defence, whether constructed against the invasion of the moth or 
 hostile bees, became an impracticable obstruction to the exit of 
 the succession of emigrating colonies, and were therefore demo- 
 lished, and were not reconstructed without pressing necessity. 
 Thus the works constructed in 1804 against the invasions of the 
 moth were taken down in the swarming season of 1805 ; and as 
 the plunderers did not re-appear in that year, they were not re- 
 erected. But in the autumn of 1807, the moths appearing in 
 great numbers, the bees immediately erected strong barricades, 
 and thus effectually prevented the disaster with which their 
 population was menaced. In the next swarming season, in May 
 1808, these works were again demolished. 
 
 It ought to be observed, that whenever the door of the hive 
 is itself too small to admit the moth, the bees erect no defences 
 against it.* 
 
 168. One of the most interesting and, at the same time, most 
 difficult question connected with the faculties of insects, is that of 
 the number and nature of their senses. It has been often and truly 
 said, that no being, however intelligent, can form even the most 
 obscure notion of a sense of which he is himself deprived. The 
 man deprived of sight, to whom the colour scarlet was elaborately 
 described, said that his notion of it was that of the sound of a 
 trumpet. Granting then the possibility that insects may be 
 endowed with a peculiar sense, or mode of perception, of which 
 we are destitute, we are in no condition to form a conception 
 of the power or impressions of such a sense, any more than the 
 blind man was who attempted to acquire a conception of a red 
 colour. 
 
 But without supposing the possible existence of peculiar senses 
 independent of the five with which we are endowed, it may be 
 that the very organs which we possess may be given with an infi- 
 * Huber, ii. 293—298. 
 
 86 
 
SENSES OF BEES. 
 
 nitely higher degree of sensibility to these minute species. Their 
 auditory organs may be such as to give them the power of ear- 
 trumpets, and their eyes may be either microscopic or telescopic, 
 or both united. Their olfactory organs may have a susceptibility 
 infinitely more exalted than ours, as indeed innumerable facts 
 prove those of many species of inferior animals to be. Art and 
 science have supplied us with numerous tests, by which the 
 physical properties of substances are distinguished, by characters 
 which escape all our senses. Why may not the Creator have 
 given to inferior animals specific organs, capable of perceiving 
 those distinctions, as surely and promptly as the eye distinguishes 
 shades of colour, the nose varieties of odour, or the ear the pitch 
 of a musical note ? 
 
 169. Among social insects, the hive-bee stands preeminent for 
 the manifestation of sensitive faculties. Sight, touch, smell, and 
 taste, are universally accorded to it. Hearing was regarded as 
 doubtful, but we have shown that a noise produced at any side of 
 a hive, will immediately bring there the queen and her court, to 
 see what is the matter. 
 
 But if the sensibility of the ear be doubted, what exaltation 
 of power do we not find in the eye ! How unerring is the per- 
 ception of her dwelling, while the bee lies at distances and under 
 circumstances, which might well appear to baffle the most acute 
 human organ, aided even by human intelligence ! The little bee, 
 issuing from her hive, departs upon her industrial excursion, and 
 flies straight to the field which she has already discovered to be 
 most fertile of honey flowers. Her route to it is as straight as 
 the flight of a bullet from a gun to the object aimed at. When 
 she has gathered her load, she rises in the air, and, flying 
 back to her hive with the same unerring certainty, finds it 
 among many, and entering it, finds the cells which are appro- 
 priated to her care. 
 
 The sense of touch is, perhaps, even more to be admired than 
 that of sight, for it supplies the place of that sense in the darkness 
 of the internal labyrinth of the hive. In darkness the architec- 
 ture of the combs is constructed, the honey is stored in the cells 
 appropriated to it, the young are nourished, their food being 
 varied with their respective ages, the queen is recognised, — and 
 all this appears to be accomplished by some sensitive power 
 possessed by the antennae, organs whose structure, nevertheless, 
 seems to be incomparably inferior to that of the human hands. 
 
 The industrial activity of the bee is much less excited by 
 warm weather and bright sunshine, than by the prospect of col- 
 lecting an abundant supply of provisions for the hive. When 
 the lindens and the buck- wheat are in flower, they brave the rain 
 
 87 
 
THE BEE. 
 
 and cold, eommencmg their excursions before sunrise, and con- 
 tinuing their work much later than their customary hours. But 
 when the flowers rich in pollen and nectar prevail in less abund- 
 ance, and when the scythe has swept away the flowers which 
 enamelled the fields, even the brightest sunshine and the warmest 
 days fail to attract the industrious population to go abroad. 
 
 170. Of all the senses of the bee, that of smell appears to be the 
 most acute. Certain odours have an irresistible attraction for 
 the insect, while others are in the same degree repugnant to it. 
 Of the former, as might naturally be expected, honey is by far 
 the most exciting. It was supposed by Huber, not without much 
 probability, that the bee is attracted to this or that flower, not 
 by its colour, form, or other visible properties, but by the odour 
 of the nectar it contains. To test this experimentally, Huber put 
 some honey in a box, so as to be invisible from the outside, and 
 placing it in the neighbourhood of his hives, found that the bees 
 crowded round it in a few minutes, finding their way to the honey 
 through a small hole left for the purpose. 
 
 171. He next made several small entrance holes in a box con- 
 taining honey, but covered each hole with a sort of card valve, such 
 that it would be possible for a bee to raise it and enter the box. 
 The box thus prepared was placed at two hundred yards from the 
 hives. In half an hour the bees found it, crowded in great 
 numbers on every side of it, examining carefully every part, as 
 if to seek for an entrance. At length, finding the valves, they 
 set to work at them, and never ceased until they succeeded in 
 raising them, when they entered and took possession of the spoil. 
 
 How exquisitely acute must be their olfactory organs will be 
 apparent, when it is considered that, in this case, the box and 
 valves must have confined very nearly the whole effluvia of the 
 honey. 
 
 172. The following remarkable proof of the tenacity of memory 
 with which the bee is endowed, is given by Huber. A supply of 
 honey had been placed in autumn upon an open window. The 
 bees had the habit of coming to feast upon it. This honey being 
 removed, the window was closed, and remained closed during the 
 winter. In the following spring the bees again found their way 
 to the same window, expecting again to find a supply there, 
 although none had been placed there. It is evident in this case, 
 that the insect must have been guided by its memory alone, and 
 that it was capable of retaining a recollection of places and cir- 
 cumstances for several months. 
 
 173. Huber made several curious and interesting experiments to 
 determine the seat of the sense of smeil. If, as was natural to 
 expect, it were situate in some of the appendages of the mouth, 
 
SMELL — MEMORY. 
 
 it would be deadened by stopping tbese, as we defend ourselves 
 from a noisome odour by stopping the nose. CatcMng several 
 bees be, therefore, held them while he stopped their mouths and 
 probosces with flour-paste, and liberating them when the paste 
 was hardened, he found that they no longer showed any sign of 
 the possession of a sense of smell. They were neither attracted 
 by honey, nor repelled by objects whose odours were known to be 
 most repugnant to them. / 
 
 174. Among the substances to whose odour the bee shows the 
 strongest repugnance, is its own poison. This was demonstrate 
 by Huber by very remarkable experiments. Having provoked 
 the insect to put forth its sting, and eject its poison, he presented 
 this offensive juice on the end of a sharp instrument to some 
 worker bees, which were quietly resting at the door of their 
 hive. A general agitation was immediately manifested among 
 them. Some launched themselves on the poisoned instrument, 
 and others fell upon the individual who held it. That it was 
 not the instrument itself which in this case provoked their rage, 
 was proved by the fact, that a similar one, bearing no poison, 
 being presented to them, did not produce any effect. 
 
 175. An inconvenient elevation of temperature and want of ven- 
 tilation will sometimes impel the bees to leave their combs, but if 
 they are excited to remain upon them by the want of feeding, they 
 know how to reconcile the conflicting impulses. In that case they 
 produce coolness and change of air without deserting the provisions 
 which surround them, or the care of their young. A certain num- 
 ber of the insects begin to flap their wings, which are thus used 
 as fans, producing currents of air. But as they are not able to 
 sustain this labour for an indefinite time, they take it by turns, 
 regularly relieving each other. 
 
 To try what the conduct of the bees would be, if by artificial 
 means the ventilation of the hive were so impeded that the usual 
 small number oi fanners would not suffice, Huber submitted hives 
 to such unusual conditions, and found that in such cases the 
 number of bees flapping their wings was augmented in the same 
 proportion as the ventilation was impeded, until at length the whole 
 population of the hive were thus occupied. 
 
 176. The antipathy which bees manifest against particular indi- 
 viduals, is generally ascribed to some odour proceeding from their 
 persons to which the insect bears a repugnance. M. de Hafor, of 
 the Grand Duchy of Baden, had been for many years an assiduous 
 cultivator and amateur of bees, and was on such friendly terms 
 with them that he could at all times approach them with impunity. 
 He would, for example, put his fingers among them, select the 
 queen, and taking hold of her, place her on the palm of his 
 
 89 
 
THE BEE. 
 
 hand. It happened that this gentleman was attacked with a 
 violent and malignant fever, which long confined him to his bed 
 and his house. Upon his recovery he, naturally enough, revisited 
 his old friends the bees, and began to caress them and renew his 
 former familiarity. 
 
 He found, however, to his surprise and disappointment, that he 
 was no longer in possession of their favour, and instead of being 
 received as formerly, his advances were resented as an unwel- 
 come and irksome intrusion ; nor was he ever afterwards able to 
 perform any of the usual operations upon them, or to approach 
 them without exciting their rage. 
 
 177. According to Dr. Bevan and M. Feburier, both close and 
 accurate observers of the habits of the insect, red and black-haired 
 persons are peculiarly obnoxious to it. Feburier mentions a 
 mastifi" to which his bees had a particular aversion, pursuing him 
 into the house with such pertinacity, that doors and windows 
 were obliged to be closed for his protection. 
 
 Dr. Bevan mentions that he had two friends, brothers, one of 
 whom was so inoffensive to the bees, that he could stand with 
 impunity over the hive and watch all their doings, while the 
 other could scarcely enter the garden with impunity. 
 
 178. The antennge are generally regarded as the proper organs 
 of the tactile sense, and hence are popularly, though not properly, 
 called feelers, — the feelers being in fact the palpi already men- 
 tioned. Naturalists are not agreed as to the functions of the 
 antennae, though all concur as to their importance. Some con- 
 sider them as organs of smell, others as organs of hearing ; while 
 others claim for them the place of organs of a sixth sense, of 
 which man and the higher animals are destitute. This sense is 
 considered by Kirby as an intermediate faculty between sight and 
 hearing, rendering the insect sensible of the slightest movement 
 of the circumambient air. Dr. Evans, as quoted by Dr. Bevan, 
 in reference to the faculty conferred on the bee by the antennae, 
 says, — 
 
 ** The same keen horns, within the dark abode, 
 Trace for the sightless throng a ready road ; 
 While all the mazy threads of touch convey 
 That inward to the mind, a semblant day." 
 
 The antennae, and the two pair of palpi, would seem to have 
 correlative and complementary functions : they are both in con- 
 stant motion. The palpi are in reality the feelers, in the proper 
 sense of the term ; as is apparent by observing the manner in 
 which the insect applies them to the food before eating it. 
 
 179. Cuvier considers the organs of taste in the bee to consti- 
 tute one of its most important characters. The sensibility of these 
 
 90 
 
TASTE — SIGHT. 
 
 organs is manifested by the delicate choice of food which the 
 insect makes, showing a preference for those flowers, wherever 
 they can be found, which yield the finest honey. Hence the cele- 
 brity of the honey of Narbonne, Hymettus, Hybla, and Pontns. 
 
 180. Numerous indications show that the bee possesses the 
 sense of hearing. The manner in which they are attracted to any 
 quarter of the hive where an unusual noise is produced, has been / 
 already mentioned. Dr. Bevan mentions some curious example^ 
 of their power of hearing, and even of the sense they seem tjo 
 attach to particular vocal sounds. Thus he mentions an old 
 dame of his acquaintance, who was a very fearless operator in the 
 treatment of these insects, and who used to suppress any move- 
 ment of anger on the part of the bees merely by saying to them, 
 "Ah! would you dare?" A servant of Mr. Knight, the well- 
 known apiarian, used to quell their anger by exclaiming, ''Get 
 along, you little fools I " 
 
 Some difference of opinion has nevertheless prevailed as to the 
 existence of this sense in insects. The opinion of Linnaeus and 
 Bonnet was against it. Many evidences, however, may be adduced 
 in favour of its existence. Thus, one grasshopper will chirp in 
 response to another, and the female will be attracted by the voice 
 of the male. Brunelli shut up a male in a box, and allowed the 
 female her liberty ; as soon as the male chirped she flew to him 
 immediately. A bee on the window within a bee-house will 
 make a responsive buzz to its fellows on the outside.* 
 
 181. The indications of a keen sense of vision, in the certainty 
 and precision with which the bee flies to its pasturage and back 
 to its hive, have been already mentioned. Naturalists, however, 
 are not agreed as to the particular power of the eyes of these 
 insects. Some, for example, contend that their sight is extremely 
 short, and that 
 
 Its feeble ray scarce spreads 
 An inch around ; 
 
 while others contend that its vision of near objects is obscure and 
 imperfect, but for distant ones quite distinct. Thus Butler and 
 Wildman say that they have observed the bees go up and down 
 seeking the door of the hive, as if they were in the dark ; but 
 Bevan observed that they easily discovered it by rising on the 
 wing, and thus throwing themselves at a greater distance 
 from it. 
 
 182. Among the mysteries of the social economy of the bee, there 
 is perhaps nothing more curious than the circumstances which, 
 in certain cases, appear to affect the personal character of the 
 
 * Bevan, p. 362. 
 
 91 
 
THE BEE. 
 
 sovereign. We have already explained that there are certain 
 periods in the life of the queen, during which she produces egg? 
 of certain sorts, — at one period those only of workers, at another 
 those onl)'- of drones. But if the epoch of her nuptials be post- 
 poned to a certain advanced period of life, at which, if we may 
 be allowed the expression, she begins to approach the condition 
 of an old maid, a singular change is found to have taken place in 
 her constitution, in consequence of which she is no longer capable 
 of having any but male offspring, in other words, she is incapable 
 of laying any but drone eggs. 
 
 183. Now since such a queen is obviously incapable of discharge 
 ing those functions, which are indispensable to the continuance oi 
 the population over which she presides, and of whose young she 
 ought, in the ordinary course of nature, to be common mother, it 
 might be inferred that the instincts of the insects would lead 
 them to disembarrass themselves of a sovereign, incapable of 
 discharging the most important functions of her office, and to 
 substitute for her, as we know they always have the power to 
 do, one who should enjoy the plenitude of these functions. 
 
 184. Among the innumerable experiments of Huber, those are not 
 least interesting which were directed to this point, that is to say, 
 to submit the faculties of the queen to tests supplied by artificial 
 means, contrived for placing her in social conditions, in which it 
 could scarcely ever happen that she should find herself in the 
 common course of bee-nature. 
 
 The first question which suggested itself to the great naturalist, 
 was to ascertain whether queens, who thus married so late in life 
 as to have only drone ofispring, would exhibit the same spirit 
 of jealous hostility towards the tenants of royal cells, and the 
 future aspirants to thrones, as is invariably manifested by younger 
 royal brides. To determine this it was necessary to place such a 
 queen in a queenless hive, in which, however, there was at least 
 one royal cell tenanted by a princess. Huber, therefore, placed the 
 queen, who had not married until she had bordered upon old 
 maidenhood, in a hive which had no queen, but in which there 
 was one royal cell occupied by a princess. The old bride, whose 
 nuptials had not been celebrated until she had attained the 
 twenty-eighth day of her age, laid nothing of course except drone 
 eggs. On being placed in the hive she exhibited none of the 
 usual signs of hostility against the royal cell. On the contrary, 
 she passed and repassed it many times a day without seeming to 
 take the least notice of it, or to distinguish it in any way from the 
 numerous cells which surrounded it on every side. In sach of 
 these latter cells as were unoccupied she deposited eggs, and not- 
 withstanding the jealous guard which the workers kept around 
 92 
 
CHARACTER OP QUEENS. 
 
 the royal cell occupied by the princess, the queen did not appear 
 either to show a disposition to attack the imprisoned princess, or to 
 fear any attack on the part of the latter. 
 
 185. Meanwhile the workers exhibited towards the queen the 
 same respect and homage, lavished upon her the same affectionate 
 cares, offered her honey, and formed round her in the same respect- 
 ful circle, as they are wont to do round a sovereign possessing ailT 
 the functions necessary to perpetuate the race. / 
 
 It appears, therefore, that the postponement of the royal nuptials 
 beyond a certain age, while it deprives the queen of the faculty of 
 having any but male offspring, also deprives her of that instinctive 
 feeling of jealous hostility towards rival queens, which forms a 
 trait so remarkable in the characters of queens, whose nuptials 
 take place at an earlier and more natural age. 
 
 To those who regard these little creatures as mere pieces of 
 mechanism, obeying unreflecting impulses, having purposes always 
 directed to the fulfilment of some important end in their economy, 
 it wiU doubtless be surprising that members of the community so 
 useless as those princesses, who postpone their nuptials until they 
 are incapable of bearing worthier offspring, should not be destroyed 
 as the drones are, after they cease to be useful. So contrary to 
 this, however, is the fact, that no royal bride, however young^, is 
 the object of solicitude more tender, affection more sincere, and 
 homage more profound, than those drone-bearing mothers. I 
 have seen," says Huber, *' the workers lavish the most tender care 
 upon such a queen, and, after her decease, surround her inanimate 
 body with the same respect and homage as they had paid to herself 
 while living, and, in the presence of these beloved remains, refuse 
 all attention to young and fertile queens who were offered to 
 them." * It must be admitted that this looks much more like the 
 tenderness of moral affection than the mechanical impression of 
 blind instinct. 
 
 186. We have already stated that the royal nuptials are always 
 celebrated in the air, and under the bright beams of the sun, 
 where the bride rises with her numerous suitors, and makes her 
 choice. This bridal excursion into the fields of ether is so inti- 
 mately interwoven with the customs of these little people, that if, 
 by cutting off her wings before her nuptials, her majesty is de- 
 prived of the power of flight, she is consigned irretrievably to a 
 life of single blessedness, since she can never submit to nuptials 
 celebrated in the recesses of the hive, instead of the gay and 
 bright sunshine of the free air. 
 
 * It will be observed that, according to the general hubit of the blind, 
 Huber uses the language of vision, and describes what he saw v/ith the 
 eyes of Bernens as if he had seen them with his own. 
 
 93 
 
THE BEE. 
 
 Lest it might be imagined, as indeed Swammerdam supposed, 
 t"hat the marriage is really consummated in this case in the hive, 
 and that her majesty is only rendered sterile by the mutilation 
 she has undergone, Huber cut off the wings of a queen imme- 
 diately after the royal nuptials, hut before her majesty had yet any 
 offspring. In this case, however, her fertility was as great as usual, 
 and she produced the customary number and variety of eggs. 
 
 187. One of the questions in insect physiology, which has been 
 attended with a certain degree of doubt, is that which regards 
 the functions of the antennae. Huber, therefore, desiring to 
 ascertain how the queen would be affected by the privation of 
 these organs, cut off first one and then both, observing the conduct 
 of her majesty after such mutilation. 
 
 The excision of one only of the antennae produced no dis- 
 coverable effect upon her faculties or conduct, but the amputation 
 of both was followed by some very remarkable consequences. 
 
 The antennae of a queen of limited fertility, who was incapable 
 of having other than drone offspring, were cut off. From the 
 moment she lost these organs she appeared to be affected by a 
 sort of delirious intoxication. She ran over the combs with extra- 
 ordinary vivacity. She did not give her suite, who formed the 
 usual circle around her, time to make way for her, but rushed 
 madly through them, violently breaking their ranks. She did 
 not deposit her eggs in cells, but dropped them at hazard. The 
 hive not being very full, there were parts of it unoccupied by 
 combs. To these parts she rushed, and remained there a con- 
 siderable time quiescent, appearing to avoid the presence of her 
 subjects. Some of them, nevertheless, followed her to these 
 deserted places, and eagerly testified their solicitude for her, 
 caressing her, and offering her honey. This she generally 
 declined ; and when now and then she seemed disposed reluctantly 
 to accept it, she appeared to lose the power of presenting her 
 proboscis to receive it, directing that organ at one time to the 
 head and at another to the legs of the workers, so that it was 
 only by chance it encountered their mouths. She would then 
 run back to the combs, and from the combs to the glazed sides of 
 the hive, in wild delirium, never ceasing to drop her eggs here 
 and there as she went along. 
 
 At other moments she seemed to be tormented with a desire tc 
 quit the hive, and rushed to the door for that purpose, but the 
 orifice being too small to allow her body to pass through it, she 
 was forced to desist, and returned to the interior. Notwithstand- 
 ing this state of delirium, the bees never ceased to lavish upon 
 her those cares which they are accustomed to bestow on their 
 queen ; but she received them with indifference. 
 94 
 
EXPEEIMENTS ON QUEENS. 
 
 Whether all this singularity and eccentricity of conduct was to 
 be ascribed to the excision of the antennae, or to that mutilation 
 combined with the partial sterility which limited her offspring to 
 drones, was not clear. To decide this point, Huber amputated 
 the antennse of a perfect queen, married at an early age, and who 
 was bearing a numerous offspring, consisting of workers, drones, 
 and princesses. This queen he placed in the same hive with the 
 former, with a view to determine at once two questions, the one 
 relating to the general conduct of the amputated queen, and the 
 other, that which regarded the mutual bearing of two mutilated 
 personages. 
 
 The general conduct was the same as that of the former queen. 
 There was the same wild delirium ; the same rushing here and 
 there as if under the influence of intoxication ; the same efforts to 
 escape from the hive; and, in a word, the same peculiarity of, con- 
 duct and manners. A like difference was apparent in their con- 
 duct towards each other. Instead of entering into deadly combat, 
 as queens in their natural state would have done in like circum- 
 stances, they met and passed each other again and again without 
 the slightest indication of mutual hostility. This is perhaps the 
 strongest proof which can be obtained, that the privation of the 
 antennae utterly subverted their natural instincts. 
 
 Another curious social anomaly was manifested on this occasion. 
 It will be recollected that where a strange queen is introduced 
 into a hive over which a regular sovereign already presides, the 
 population surround her, confine her as a prisoner within a ring 
 of sentinels, and refuse to permit her to enter their city. In the 
 present case, no such measures were adopted. On the contrary, 
 the second mutilated queen was received with the same signs of 
 welcome, and immediately became the same object of attention 
 and homage as the first. 
 
 But the most wonderful fact of all those developed in this 
 series of experiments, was that when a third queen in the perfect 
 state, without mutilation, was introduced, the bees who had 
 already treated the other two so well, immediately proceeded to 
 maltreat this third and perfect queen. They seized her, dragged 
 her about, bit her, and so closely surrounded her as to leave her 
 room neither to move nor to breathe. 
 
 Having observed the apparent desire of these mutilated queens 
 to issue from the hive, which they were only prevented from 
 doing by the limited magnitude of the door, and desiring to see 
 whether the bees or any considerable number of them would 
 depart with her, as they would do with a perfect queen, Huber, 
 after taking away the two queens who were sterile, or partially 
 so, and leaving her who was fruitful in all respects, but deprived 
 
 95 
 
THE BEE. 
 
 of her antennre, he enlarged the door so as to allow her free 
 passage through it. So soon as this was done, she went out, and 
 took flight, but not a single bee accompanied her. She was, 
 moreover, so heavy, being full of eggs, that she was not able long 
 to sustain herself on the wing, and fell to the ground. 
 
 Yarious conjectures are made by Huber to explain this singular 
 departure from the prevailing habits of the insect, but none of 
 them appear so satisfactory as to require to be reproduced. 
 
 96 
 
Fig. 85.— Oblique piece to elevate 
 a village hive. 
 
 Fig. 86. — The bee-dress. 
 
 THE BEE. 
 
 CHAPTER VII. 
 
 188, Apiculture. — 189. Suitable localities and pasturage. — 190. Tte 
 Apiary. — 191. Out-door Apiary. — 192. Bee-liouse. — 193. Cabiaet 
 bee-houses. — 194. Form and material of liives. — 195. Village hive. — 
 196. English hive. — 197. Various forms of hives. — 198. Various 
 forms of bee-boxes. — 199. Bee-dress and other accessories of apicul- 
 ture. — 200. Purchase of hives. — 201. Honey harvest. — 202. Honey 
 and -wax important articles of commerce. — 203. Vjarious sorts of -wild 
 honey. — 204. Periodical migration of bees,— 205. Poisoned honey. 
 — 206. Maladies of bees. — 207. Curious case of abortive brood. — 
 208. Superstition of bee cultivators. — 209. Enemies of bees. — 210. 
 Attacks of bees when provoked. — 211. Anecdote of Mungo Park. — 
 212. Anecdote of Thorley. — 213, Bee -wars. — 214. Curious case of a 
 battle. 
 
 188. Apiculture is tho name given to the art by which the 
 products of the industry of the bee are augmented in quantity, 
 improved in quality, and rendered subservient to the uses of man, 
 
 189. The most favourable localities for the practice of apicul- 
 ture are of course those of which the climate is suitable to the 
 habits and character of the insect, and which most abound in those 
 vegetable productions on which it loves to feed. Among these 
 the principal are saintfoin, Dutch clover {trifolium repens), buck- 
 wheat, rape, honeysuckle, clover (trifolium pratense), and yellow 
 trefoil {medicago lupulina). According to Dr. Bevan, tbe earliest 
 
 Lardher's Museum of Science, h 97 
 
 Kc. 129. 
 
THE BEE. 
 
 resources of the bee are, however, the willow, hazel, osier, poplar^ 
 sycamore, and plane; to which may be added, the snow-drop, 
 crocus, white alyssum, laurustinus, orange and lemon trees, 
 gooseberry and currant and raspberry bushes, sweet marjora?n, 
 winter-savory, thyme, and mint. In a word, fruit-trees and green- 
 house plants and shrubs in general, such especially as abound in 
 ornamental grounds, all constitute a part of bee-pasturage. 
 
 ** First the gray willows' glossy pearls they steal, 
 Or rob the hazel of its golden meal ; 
 While the gay crocus and the violet blue 
 Yield to the flexile trunk ambrosial dew. 
 
 Evans, quotea by Bevan. 
 
 An undulating country is highly favourable to the bee. 
 
 190. The apiary should be near the dwelling-house, in the garden, 
 and in a position sheltered from unfavourable winds. The farm 
 and poultry-yard should be avoided, as well as too great proximity 
 to railways, forges, factories, bakehouses, workshops, and the like. 
 The bee loves tranquil spots, planted with ornamental shrubs 
 and fruit-trees, and sown with sweet flowers, such as mignonette, 
 thyme, mint, rosemary, &c. The aspect of the apiary may be 
 east, west, or south, according as the one or other affords best 
 shelter, but never north. 
 
 191. The hives should be placed on separate stands, a few feet 
 apart, should be clear of any wall or fence, and elevated eighteen 
 inches or two feet above the ground. 
 
 Hives are sometimes assembled together in the open air, 
 forming an out-door apiary, such as is shown in fig. 54, p.l, in 
 which case they are generally made of straw, and protected in cold 
 weather by straw roofs, but sometimes also formed of wooden 
 boxes, as shown in the figure. 
 
 This arrangement, having the advantage of simplicity and 
 cheapness, is most commonly adopted, especially by those to whom 
 economy is important, and in warm climates where shelter is less 
 Necessary. 
 
 192. Under other circumstances bee-houses are much more 
 strongly recommended, as well for comfort and convenience as for 
 security. The bee-house, one form of which is shown in fig. 55, 
 p. 33, consists of two or more rows of shelves, established one 
 above the other, on which the hives are placed at distances of 
 from twelve to eighteen inches apart, so that the bee-doors shall 
 be from two to three feet asunder. The house should be thatched 
 not only on the roof but on the sides and ends. A passage should 
 be provided for approaching the hives behind, and windows in the 
 side for ventilation. 
 
 193. A form called the Cabinet bee-house is shown in fig. 56, 
 98 
 
p. 65, where B b are doors/one of which is glazed, and A a pipe 
 of tin or caoutchouc, by which the bees. have ingress and egress. • 
 
 194. Hives have been constructed of different materials, as straw^ 
 ^siej-s, rushes, sedges, wood, ajid earthenware ; and of still more 
 various forms, some hieing hell- shaped or conical, some cylindrical.' 
 some square in their section, some with rectangular and some 'witK 
 oblique tops, , being internally divided by comb-frames fixed 6iL 
 movable, by shelves, and other expedients. 
 
 Their forms of structure depend in some degree upon the obtecf 
 of the proprietors. ,When apiculture is prosecuted on a Idige 
 gcale for the produce of honey and wax, as arti<;les of trade, the 
 foreign cultivators prefer hives of . the most simple forms and 
 most easy construction, and those from which the products can be 
 c^tained with most facility. The. material preferred is, generally, 
 straw or rushes. The process of making such a hive is indicated 
 in fig. 57. 
 
 Fig. 57. — Process of making 
 a straw hive. 
 
 Fig. 61. — Movable comb- 
 frame of the village 
 hive. 
 
 Fig. 59.— Top of the 
 cylindrical body of 
 the village hive. 
 
 195. The bell-shaped straw hive, called the village hive, repre- 
 sented on the right of fig. 58, p. 49, is cylindrical in the body, 
 and surmounted by a bell-shaped cap. The top of the cylindrical 
 body is covered by a frame of bars, shown separately in fig. 59 
 and the cap itself is shown in fig. 60. 
 
 Fig. 60.-Cap of the ■ ■ " ' """""""""""""""""I"'""""""""'"'"" 
 
 village hive. , . ^ , 
 
 Fig. 62.— Dewhurst's hive. 
 
 One of the movable comb-frames is shown in fig. 61, where A 
 is the vertical section of the stage^ shown by plan in fig. 59 ; b 
 the uprights, and c a shelf shown in vertical section. 
 
 H 2 99- 
 
THE BEE. 
 
 . .196. The Ei^Ush hive-of Dewliurst, liaviiig a box at tlie top, is 
 Bliown in fig. 62 ; where A is the body of the hive, b the opening 
 at the top, and c the box provided with shutters. 
 
 197. In. fig. 63, p. 81, is shown a form of straw hive used in 
 Scotland, a,nd,in . fig. 64 the Eadouan hive, similar in form to 
 the village hive, but provided with movable pieces, by placing 
 which successiyely below it, its elevation can be gradually 
 augmented without disturbing the superior part, so as to give 
 increased space to the bees and prevent the issue of swarms. 
 
 A form of hive much used in the South of France, and known 
 to French apiarists as the Vulgar Hive (Ruche Vulgaire), is shown 
 on the left of fig. 58, p. 49, in the process of transferring the bees 
 from one hive to another. 
 
 A form of cork hive used in the South of France is shown in 
 
 fit?. 66.— Cylindrical hive Fig. 67.— Delia Rocca hive (Greece 
 
 (Switzerland and Italy). and Turkey). 
 
 fig. 65 ; and a cylindrical hive with its axis horizontal, much 
 
 Fig. 69.— De Frftrifere's gardeii hive. 
 
 used in Switzerland and Italy, is shown in fig. 66. 
 100 
 
BEERHOUSES. 
 
 In Greece and Turkey a hiVe of earthenware, known as that of 
 della Rocca, is much used, fig.' 67. • 
 
 Straw hives have the advantage over wooden hoxes in being 
 hetter non-conductors of heat, and therefore preventing immo- 
 derate cold in winter and immoderate heat in sumraer in the 
 
 Fig. 70.— Patteau's bee-box, with Fig. 71. — Gdlieu's bee-box, with vertical 
 horizontal divisions. diyisipa. , 
 
 interior. They are on this accoimt preferred where the apiary is 
 uncovered. 
 
 198. When apiculture is practised partly for the purpose of 
 
 Fig. 72.— Feburier's bee-box, with vertical Fig. 73.— Huber's experimental 
 division and sloping roof. leaf-hive. 
 
 observing the habits of the insect, boxes with divisions and 
 
 101 
 
. THE BEE. 
 
 movable comb-frames, with glazied openings and other like con- 
 trivances, are used. These hee-boxes, as they are called, are 
 
 Fig. Ti.— Debeauvoy's bee-box, with 
 ^plopiug roof iiud shelves. 
 
 infinitely various in form, and although our limits will not allow 
 us to enter into the details of the advantages derived from them 
 
 Fig. 77. — Debeauvoy's box, with 
 vertical frames. 
 
 by their inventors and contrivers, it will nevertheless be useful to 
 show the furms of those most generally used. 
 
 The common bee-box used in the South of France is shown ia 
 fig. 76, p. 17, the cover c being hinged, so as to be capable of 
 being raised at pleasure. The process of transferring the beea 
 a02 
 
BEE-HOUSES. 
 
 Figf. 78.*— Lefebvre's box, with mov- 
 able framea. a, a frame drawn out. 
 
 Fig. *I0. — Hamet's bee-box> 
 with oblique liorizontai 
 divisions. 
 
 Fig. 80. — One of the divisions by 
 which fig. 79 is elevated, with 
 a movable frame, a, drawn 
 
 ■ out. 
 
 Fig. 81.— Hamet's bee-box, with, 
 divisions arid movable frames. 
 
 from one hive to another by smoking them, is indicated, and alsd 
 th6 method of hiving a swarm. 
 
 Fig. 82.— Uprights 
 of fig. 81. 
 
 Fig. 83.— Frame ot 
 fig. 81. 
 
 Fig. 84.— Side of fig. 81, with 
 its movable frame. 
 
 199. In' the practical details of apiculture there are many 
 
 103 
 
THE BEE. 
 
 Fiff. 87. Fig. 83- 
 
 accessories, some of which are of occasional, and others of 
 constant use. 
 
 The bee-dress, fip. 80, is a sort of armour, by which the operator 
 is protected from all hostile attacks of the insect. It in usually 
 made of Scotch gauze, or catgut, and so formed aa to inclose the 
 head, neck, and shoulders, as shown in lig. 76, p. 17, where a 
 person invested with such a dress is represented in the act of 
 hiving a swarm. It should liavo long sleeves to tie round the 
 wrists over a pair of thick gloves, and the body should descend 
 low enough to be tied round the waist. Thick 
 woollen stockings and a woollen apron are recom- 
 mended, the material being one from which the 
 bee can readily withdraw its sting. 
 
 Knives of different forms (figs. 87, 88) should 
 be provided, for the partial removal of the honey- 
 combs, when the smothering process is not re- 
 sorted to. 
 
 A bellows connected with a fumigator (fig. 89) 
 for projecting tobacco-smoke into those parts of 
 the combs from which it is desired to expel the 
 bees, should be provided. 
 
 A hive with a handle for mixing swarms is 
 often useful (fig. 90). 
 
 A basket, with an open bottom, placed over 
 a tub for the purpose of draining the honey-combs, is also a 
 convenient accessory (fig. 91). 
 
 200. A hive should, in general, be purchased in autumn, and 
 its value will be pretty well ascertained by its weight. That of 
 a good hive which will be sure to go through the winter, and 
 to be productive in the ensuing season, should be from 25 
 to 30 lbs., and should contain about a peck of bees. If the 
 weight be much greater than 30 lbs., a part of the honey 
 may be advantageously taken out. Hives are to be preferred 
 which are only a year old, and which have sent out no more 
 than a single swarm. Such will be distinguished by the 
 superior whiteness and purity of the combs. The transport 
 should be made in cool weather, and should be conducted without 
 shocks or jolts. 
 
 201. Honey should never betaken from any but the nearest and 
 most populous hives. If they are j)rovided with movable comb- 
 frames, it is usual to make a partial harvest in May, the principal 
 stores of the insect being collected between the middle of May and 
 the end of June, the commencement and termination, however, 
 varying three or four weeks, according to the climate peculiar to 
 the locality. 
 
 104 
 
COLLECTION OP HONEY. 
 
 Dr. Bevan recommends, as a general rule, that no honey should 
 be taken from a colony the first year of its being planted. 
 
 Fig. 90. 
 
 To make a partial collection of honey, the hive is opened at the 
 top or at the side, and the bees expelled from the combs by puffing 
 tobacco-smoke upon them. The combs are then cut away with 
 knives of suitable forms (figs. 87, 88). This operation requires 
 to be performed with skill and care, so as to avoid as much as pos- 
 sible irritating the bees. To withdraw the queen from the part of 
 the combs which are to be removed, the operator taps with his 
 fingers on the opposite part of the hive, which will cause her 
 majesty to run there, to ascertain the cause of the noise. If any 
 bees are seen upon the combs removed, they may be brushed off 
 with a feather, when they will generally return to the hive. The 
 combs taken away are replaced either by empty ones, or by full 
 combs taken from the lower part of the hive. 
 
 When hives are constructed on the principle of those shown in 
 fig. 64, &c., consisting of several parts separable, laid one upon 
 the other, the honey may be collected by causing the bees to 
 desert the division intended to be removed by tapping on remote 
 parts of the hive, and by projecting tobacco-smoke on them. 
 
 These operations may be performed in the day between ten and 
 three o'clock. If the country be one rich in bee pasturage, a 
 superior division of the hive may be taken away and replaced by 
 an empty one, if the operation take place early in the season ; and 
 this latter may sometimes be again harvested before the close of 
 the season, so as to obtain honey of the purest and finest quality. 
 
 105 
 
THE BEE. O 
 
 But where tlie pasturage is not so rich, or where the operation is 
 performed later in the season, it will be necessary either not to 
 replace the division harvested, or to put the empty division at the 
 bottom of the hive. 
 
 To collect the honey in the hives of the form represented in 
 fig. 58, p. 49, called the vulgar hive, it is necessary either to expel 
 the bees or to smother them. 
 
 To expel and transfer them to another hive, that which is to be 
 harvested is inverted, as shown in fig. 58, p. 49, and over it is 
 placed the hive to which the bees are to be transferred. The bees 
 may be driven from one to the other, either by being smoked, as 
 shown in fig. 76, p. 17, or by tapping upon the superior hive, 
 fig. 58, p. 49. 
 
 If some bees remain in the hive to be harvested, they will 
 voluntarily pass into . the new hive by the arrangement repre- 
 sented in fig. 76, p. 17. 
 
 When the hive is harvested, either wholly or partially, by 
 affecting the bees with temporary asphyxia, the process is as 
 follows : after having beaten the black powder from a puff-ball of 
 Lycoperdon, it is placed with some red charcoal in the fumigator, 
 fig. 89, the nozzle of which is inserted at the door of the hive. 
 The bellows being worked for five or six minutes, the bees will 
 fall insensible from the hive, when the combs may be removed, 
 wholly or partially, as the case may be. In twenty or thirty 
 minutes the bees will revive, and re-enter the hive, or may be 
 received in a new one if desired. 
 
 If it be not desired to. preserve the bees, the hive may be 
 placed over a pit into which they will fall, and where they may- 
 be buried. 
 
 To obtain honey of the first quality, the purest combs, con- 
 taining neither bee-bread nor brood, being selected, are drained 
 through a hair-sieve or osier-basket. Their product, called 
 virgin honey, is limpid. It hardens and keeps if potted and put 
 in a cool and dry place. Honey of inferior quality is obtained 
 by pressing the residue of the combs, and exposing them to heat. 
 
 "Whenever honey is collected, wax may also be obtained, but 
 .the latter substance may be separately collected at the close of 
 the winter, by paring away the lower ranges of comb, taking 
 away by the knife those which are old, black, and mouldy, and 
 those which have been attacked by the moth. The wax is dis- 
 solved with boiling water, after which it is purified and collected 
 in moulds of glazed pottery. 
 
 202. Honey and wax, the products of bee industiy, form 
 important articles of commerce in various parts of the world. 
 
 Although the production of wax is not confined to the bee, 
 106 
 
HOmY AND WAX. 
 
 nearly all of that article employed in Europe is of bee manu- 
 facture. 
 
 Although honey has lost much of its importance as an article of 
 food, since the discovery and improvement of the fabrication of 
 sugar, it is still regarded as a luxury, and of considerable value 
 in this country, as the material out of which a wholesome vinous 
 beverage is produced. In many inland parts of the continent 
 where sugar is costly, few articles of rural economy could be less 
 spared. In the Ukraine some of the peasants possess from 400 to 
 500 hives, and are said to make more profit of their bees than 
 even of their corn. In Spaili the nurture of bees is carried to a 
 still greater extent ; according to Mills, a single parish priest was 
 known to; possess the almost incredible number of 5000 hives. 
 
 The common hive-bee is the same, according to Latreiile, in 
 every part of Europe, except in some districts of Italy, where a 
 species called the Apis ligustica of Spinola is kept. This species 
 is also said to be cultivated in the Morea and the Ionian Isles. 
 Honey, however, is also obtained from many other species of bees, 
 as well wild as domesticated. 
 
 203. The rock honey of some parts of America, which is very 
 *hin and as clear as water, is the produce of wild bees, which sus- 
 pend their clusters of thirty or forty waxen . cells, resembling a 
 bunch of grapes, from a rock. In South America large quantities 
 of honey are ■ collected from 'nests built in trees by the Trigona 
 Amalthea and other species of this genus, under which, according 
 to Kirby, should be included the Bamburos, to gather the honey 
 of which the whole population in Ceylon make excursions into 
 the woods. 
 
 According to Agara, one of the chief articles of food of the 
 Paraguay Indians is wild honey. 
 
 Captain Green observes, that in the Island of Bourbon, where 
 he was stationed for some_ time, there is a bee which produces 
 honey much esteemed there, of a green colour, having the con- 
 sistency of oil, and which, besides the usual sweetness of honey, 
 has a remarkable fragrance. This green honey is exported to 
 India in considerable quantities, where it bears a high price. 
 
 A species of bee called the Apis fasciata was probably culti- 
 vated ages before the present hive-bee was attended to. Thi» 
 species is still so extensively cultivated in Egypt that Mebuhr 
 met on the liill between Cairo and Damietta a convoy of 
 ^000 hives, which the apiarists of that country were transporting 
 from a region where the season had passed, to one where the 
 spring was later. 
 
 204. This periodical migration of bees is by no means of modern 
 date. According to Columella, the Greeks used to send their 
 
 107 
 
THE BEE. 
 
 bee-hives at certain seasons of tlie year from Achaia into Attica, 
 and a similar custom still prevails in Italy, and even in this 
 country in the neighbourhood of heaths. 
 
 Among the domesticated species of bees may be also mentioned 
 the Apis unicolor in Madagascar, the Apis Indica at Pondicherry 
 and in Bengal, and the Apis Adansonii at Senegal. 
 
 Fabricius affirmed that the Apis Acraensis laboriosa, and 
 others in the East and West Indies, might be domesticated with 
 greater advantage than even the common hive-bee of Europe, 
 called the Apis mellifica. 
 
 205. Honey is one of the class of aliments which requires to be 
 used with some precaution, since not only are certain constitutions 
 of body affected injuriously by it, even in its most natural and 
 wholesome state, but it happens occasionally that the insects which 
 collect it resort to poisonous flowers, which impart their noxious 
 properties to the honey extracted from them. 
 
 Kirby mentions the case of a lady of his acquaintance upon 
 whom ordinary honey acted like poison, and says, that he heard 
 of instances in which death ensued from eating it. 
 
 But where the bee unfortunately resorts to poisonous plants, 
 the consequences are not thus limited to individuals of peculiar 
 idiosyncrasies. Dr. Barton has given a remarkable example of 
 this.* • 
 
 In the autumn and winter of the year 1790, an extensive 
 mortality was produced amongst those who had partaken of the 
 honey, collected in the neighbourhood of Philadelphia. The 
 attention of the American government was excited by the general 
 distress ; a minute enquiry into the cause of the mortality ensued, 
 and it was satisfactorily ascertained that the honey had been 
 chiefly extracted from the flowers of Kalmia latifolia. Though the 
 honey mentioned in Xeuophon's well-known account of the effect 
 of a particular sort, eaten by the Grecian soldiers during the cele- 
 brated retreat, after the death of the younger Cyrus, did not 
 operate fatally, it gave those of the soldiers who ate it in small 
 quantities the appearance of being intoxicated, and such as par- 
 took of it freely, of being mad or about to die, numbers lying on 
 the ground as if after a defeat. A specimen of this honey, which 
 stUl retains its deleterious properties, was sent to the Zoological 
 Society in 1834 from Trebizond, on the Black Sea, by Keith 
 E. Abbott, Esq. 
 
 206. The maladies of the bee proceed from three causes, — hun- 
 ger, damp, and infection ; all of which admit of prevention when 
 the insect is maintained artificially. 
 
 * American Philosophical Transactions, vol. v. of the year 1790. 
 108 
 
MALADIES OP BEES. 
 
 Dysentery is the malady wMch is at once the most dreaded by 
 bee-owner, and the most easy to be prevented. It is always due 
 to damp or to bad diet, such as impure honey and indigestible 
 syrups. The remedies are consequently to place the hives in a 
 dry situation, and to supply the insects with wholesome food, such 
 as good honey mixed with a little generous wine. The greatest 
 care should also be taken to remove such combs as may be 
 rendered foul by excrement, and to clean the shelves in the 
 bee-houses. 
 
 Among other maladies may be mentioned, diseases of the 
 antennae, vertigo, and abortive broods of eggs. These are gene- 
 rally produced by bad food, damp, and drafts of cold air. On 
 that account some bee-cultivators reject the forms of hive or bee- 
 houses having two doors on opposite sides, thus placed for the 
 purpose of ventilation. This arrangement is never seen in the 
 natural habitations of the insect. 
 
 207. Dr. Bevan mentions a case of abortive brood which occur-^ 
 red in one of Mr. Dunbar's hives. The colony had been very 
 strong in the previous autumn, and possessed a fertile queen, but 
 in the spring it failed, and did not swarm. On examination, he 
 found the four central leaves of the hive (which was one of Huberts, 
 fig. 73), full of abortive brood, by the presence of which the queen 
 seemed to be paralysed, though she still laid a few eggs at the 
 edge of the combs. As the population seemed gradually dimi- 
 nishing, Mr. Dunbar cut out the whole of the abortive brood, 
 removed the old queen, and added an after swarm to the family. 
 The conjoined bees soon betook themselves to work, replaced the 
 old combs by new ones, and laid in an ample store of honey. This 
 • is an operation called castration by French apiculturists ; and in 
 all such cases it is prudent, in order to prevent contagion, to have 
 the infected combs burnt or buried. 
 
 208. Butler, in his Female Monarchy," relates a story of a 
 credulous lady who devoted herself to the cultivation of bees. 
 This person having gone to receive the sacrament, retained the 
 consecrated wafer ; and at the suggestion of a friend, more simple 
 than herself, placed it in one of her diseased hives. The bee 
 plague, according to her report, immediately ceased ; honey accu- 
 mulated ; and, on examining the inside of the hive, she found 
 there, to her astonishment and admiration, a waxen chapel, of 
 wondrous architecture, supplied with an altar, and even with a 
 steeple, and a set of bells, all constructed of the same material. 
 
 209. The most dangerous enemies of the bees are the larvae of 
 certain moths, which when once they take possession of a hive can- 
 not be extirpated, and no remedy remains but to transport the 
 entire population of the insect colony to a new habitation. 
 
 109 
 
THE BEE. 
 
 The bee-louse, an insect about the size of a flea, often infests 
 populous hives, so as greatly to annoy the bees by fixing itself 
 upon them. Sometimes two or more attach themselves to a single 
 bee, making it restless and indisposed for its usual industry. 
 
 A magnified view of one of these parasites is shown in fig. 92, 
 as seen from above ; and in fig. 93, as seen from below. 
 
 Fig. 92.— Bee Louse, Fig. 93.— Bee-Louse, 
 
 seen from above. seen from below. 
 
 That universal plunderer the wasp, and his formidable congener 
 the hornet, often seize and devour them ; sometimes ripping open 
 their body to come at the honey, and at others carrying ofi" that 
 part in which it is situated. "Wasps frequently take possession 
 of a hive, having cither destroyed or driven away its inhabitants, 
 and consume all the honey it contains. Nay, there are certain 
 idlers of their own species, called by apiarists, corsair bees, which 
 plunder the hives of the industrious. 
 
 210. Examples have been already cited, in which bees have 
 manifested peculiar personal antipathies, which have been 
 Ascribed, in the cases mentioned, to some odour, ofiensive to 
 the insect, proceeding from the obnoxious individuals. Inde- 
 pendently, however, of such general causes of hostility, the 
 insects are sometimes provoked against even their best friends 
 and most familiar acquaintances, by occasional circumstances, 
 Kirby relates, that although he was generally exempt from their 
 hostility, he could not venture with impunity to put them out 
 of humour. Thus happening one day, during the season when 
 asparagus was in blossom, to pass among the beds, which were 
 crowded with bees, he discomposed them so much that he was 
 obliged to make a hasty retreat, pursued by a swarm of his 
 ofiended friends. 
 
 211. In Mungo Park's last mission to Africa, he was much 
 annoyed by bees. His people, searching for honey, having dis- 
 turbed a large colony of them, the insects sallied forth by myriads, 
 and attacking men and beasts indiscriminately, put them all to 
 the rout. One horse and six asses were killed or missing in con- 
 sequence of their attack, and for half an hour the bees seem to 
 have completely put an end to their journey. Isaacs, upofli 
 
 110 
 
MALAPIUS OF BEES. 
 
 another occasion, lost, One of Ms asses, and one of his men was 
 almost killed by them.* 
 
 ^ 212. Bees, however, as we have already observed, are not 
 usually ill-tempered ; and, if not molested, are generally inoffen-^ 
 sive. Thorley relates, f, that a maid servant, who assisted him in; 
 hiving a swarm, being rather afraid, put a linen cloth as a defence 
 over her head and shoulders. When the bees were shaken from 
 the tree on which they had alighted, the queen probably settled 
 upon this cloth, for the whole swarm covered it, and then getting- 
 under it, spread themselves oyer her face, neck, and bosom, so- 
 that when the cloth was removed, she was. quite a spectacle. She, 
 was with great difficulty kept from running off with all the bees, 
 upon her. But at length her master quieted her fears, and began' 
 to search for the queen. He succeeded, and' expected that when. 
 he put her into the hive the bees would follow. He was, however, 
 in the first instance disappointed, for they did not stir. Upon 
 examining the cluster again, he found a second queen, or probably 
 the former one, which had flown back to the swarm. Having 
 seized her, he placed her in the hive, and kept her there. The 
 bees soon missed her, and crowded into the hive after her, so that, 
 in two or three minutes, not one remained on the poor frightened 
 girl. After this escape she became quite a heroine, and would 
 undertake the most hazardous employment about the hives. 
 
 213. The duels of rival queens have been already mentioned. 
 Similar combats take place occasionally between the workers of 
 one hive and those of another. ITor are such wars confined to 
 single combats. General actions take place now and then between 
 neighbouring, colonies. This occurs when one takes a fancy to a 
 hive which another has pre-occupied. Eeaumur witnessed one of 
 these battles, which lasted a whole afternoon, and in which great 
 numbers fell on the one side and the other. In such cases, each 
 combatant selects his opponent, and the victorious one files away 
 with the slain body of its enemy between its legs. After making 
 a short flight thus, she deposits it on the ground, and rests near 
 it, standing on her four anterior legs, and rubbing the two hinder 
 legs against each other, as though she enjoyed the sight of her 
 victim. 
 
 214. The following account of a bee battle was published in a 
 Carlisle newspaper, A swarm of bees flying over a garden, where 
 a newly tenanted hive was placed, suddenly stopped in their 
 flight, and, descending, settled upon the hive, completely covering 
 it. In a little time, they began to make their way to the door, 
 and poured into it in such numbers, that it became completely 
 
 * Park's Last Mission, 153, 297. f Thorley, 150. 
 
 Ill 
 
THE BEE. 
 
 filled. A loud humming noise was heard, and the work of de- 
 struction immediately ensued. The winged combatants sallied 
 forth from the hive until it became entirely emptied, and a fero- 
 cious battle commenced in the air between the besiegers and the 
 besieged. These intrepid warriors were so numerous, that they 
 literally darkened the sky overhead like a cloud. Meanwhile, 
 the destructive battle raged with great fury on both sides, and 
 the ground beneath was covered with the killed and wounded. 
 Hundreds were seen dispersed on the ground, lying dead, or 
 crawling about in a disabled state. To one party at length the 
 palm of victory was awarded, and they settled upon a branch 
 of an adjoining tree, from which they were removed to the deserted 
 hive, of which they took quiet possession, and commenced and 
 continued their usual industry. 
 
 112 
 
 ■f 
 
STEAM NAVIGATION. 
 
 CHAPTEE I. 
 
 1. Inventors of steam navigation uneducated. — 2. First steamers on the 
 Hudson and the Clyde. — 3. Sea-going steamers due to British 
 engineers. — 4. Progress of steam navigation from 1812 to 1837. — 
 5. Atlantic steamers projected. — 6. Abstract possibility of the 
 voyage could not be doubted. — 7. The voyage had been already made 
 by two steamers. — 8. Projects advanced in 1836. — 9. Discussion at 
 Bristol in 1837. — 10. Report of Dr. Lardner's speech in the Times of 
 27th August, showing the falsehood of the report that he pronounced 
 the project impracticable. — 11. Atlantic steam voyage advocated by 
 Dr. Lardner in 1836-7. — 12. The practical results of the various 
 projects prove the truth of his predictions. — 13. The Cunard 
 steamers, established on the conditions suggested by him, were alone 
 successful. — 14. Voyages of these steamers. — 15. Other lines 
 established. — 16. Probable extension of steam navigation to the 
 general purposes of commerce. — 17. Auxiliary steam-power the most 
 probable means of accomplishing this. — 18. Advantages of subaqueous 
 propulsion. — 19. Means of realising them. — 20. Improved adaptation 
 of steam-power to vessels of war required.^ — 21. Mercantile steam- 
 marine available for national defence. — 22. Principle of marine- 
 engine. — 23. Propellers. — 24. Paddle-wheels and screws. — 25. 
 Arrangement of paddle-wheels.— 26. Paddle-shaft.— 27. General 
 arrangement of marine-engine. 
 
 IjArdnbr's Museum OP Science, 113 
 No. 120. 
 
STEAM NAVIGATION. 
 
 1. If the spirits of "Watt, Trevithick, and Fulton can look down 
 »n the things of this nether world, and behold the grand results 
 their discoveries and inventions have produced, what triumph 
 must be theirs ! For half a century the steam-engine had re- 
 mained a barren fact in the archives of science, when the self- 
 taught genius of the Glasgow mechanic breathed into it the spirit 
 of vitality, and conferred upon it energies by which it revived the 
 drooping commerce of his country, and, when the auspicious 
 epoch of general peace arrived, difiused its beneficial influence to 
 the very skirts of civilisation. Scarcely had the fruit of the 
 labour of Watt ripened, and this great mover been adopted as 
 the principal power in the arts and manufactures, than its uses 
 received that prodigious extension which resulted from its acquir- 
 ing the LOCOMOTIVE character. As it had previously displaced 
 animal power in the mill, and usurped its nomenclature, so it 
 now menaced its displacement on the egad. A few years more 
 witnessed perhaps the greatest and most important of all the 
 manifold agencies of steam — that by which it has given wings to 
 the ship, and bade it laugh to scorn the opposing elements, trans- 
 porting it in triumph over the expanse of the trackless ocean, 
 regardless of wind or current, and conferring upon locomotion 
 over the deep a regularity, certainty, and precision, surpassed by 
 nothing save the movement of chronometers or the course of the 
 heavenly bodies. Such are the vast results which have sprung 
 from the intelligence of men, none of whom shared those privi- 
 leges of mental culture enjoyed by the favoured sons of wealth ; 
 none of whom grew up within the walls of schools or colleges, 
 drawh>g inspiration from the fountains of ancient learning ; none 
 of whom were spurred on by those irresistible incentives to genius 
 arising from the competition of ardent and youthful minds, and 
 from the prospect of scholastic honours and professional advance- 
 ment. Sustained by that innate consciousness of power, stimu- 
 lated by that irrepressible force of will, so eminently characteristic 
 of, and inseparable from, minds of the first order, they, in 
 their humble and obscure positions persevered against adverse and 
 embarrassing circiimstances, impelled by the faith that was in 
 them, against the doubts, the opposition, and, not unfrequently, 
 the ridicule of an incredulous world, until at length, by time and 
 patience, truth was triumphant, and mankind now gathers the 
 rich harvest sown by these illustrious labourers. 
 
 2. It was about the eighth year of the present century that 
 Fulton launched the first steamboat on the Hudson. After the 
 lapse of four years the first European steamboat was established 
 on the Clyde. From that time the art of steam -navigation, in 
 *he two great maritime and commercial nations, advanced with a 
 
 114 
 
INLAND STEAM NAVIGATION. 
 
 steady and rapid progress. But it took different directions, 
 governed by the peculiar geographical and commercial circum- 
 stances attending these countries. The genius and enterprise of 
 the United States saw before and around it a vast territory, inter- 
 sected by navigable rivers of unequalled length, forming lines of 
 water communication on a colossal scale between its extensive 
 interior and the sea-board. The Mississippi and its tributaries, 
 with their sources, lost in distant tracts as yet untrodden by 
 civilised man, and navigable by large vessels for many thousands 
 of miles, — the Hudson, all but touching upon those magnificent 
 inland seas that stretch along the northern boundary, and are 
 almost connected with the Mississippi by the noble stream of the 
 Illinois, — the Delaware, the vast Potomac, and, in fine, a coast 
 thousands of miles in extent, fringed by innumerable bays and 
 harbours, and land-locked basins having all the attributes of 
 lakes, — these addressed themselves to the eye of the engineer and 
 the capitalist, and determined the direction of enterprise. The 
 application of steam power to inland navigation — the construc- 
 tion of vessels suited to traverse with speed, safety, and economy, 
 rivers and lakes, harbours, bays, and extensive inlets — this was 
 the task and the vocation of the American engineer, and this the 
 interest of the capitalist and the merchant.* 
 
 3. The problem of steam-navigation, however, presented itself 
 to the British engineer under other conditions. In a group of 
 islands intersected by no considerable navigable rivers, and 
 neither requiring nor admitting any inland navigation save that 
 of artificial canals, — separated, however, from each other and 
 from the adjacent continent of Europe by straits, channels, gulfs, 
 and other arms of the sea, — ^it was apparent that if steam power 
 should become available at all, it must be adapted to the naviga- 
 tion of these seas and channels — it must be adapted to accelerate 
 and cheapen the intercourse between the British islands, between 
 port and port upon their .coasts, between them and the various 
 ports on the adjacent coast of Europe, and finally to establish a 
 communication with the Mediterranean and the coasts of Africa, 
 Asia, and Europe, which are washed by it. While the American, 
 therefore, was called on to contrive a steam-vessel adapted to 
 inland and smooth- water navigation, the British engineer had the 
 more difficult task, to construct one which should be capable of 
 meeting and surmounting all the obstructions arising from the 
 vicissitudes of the deep. 
 
 The result of the labour and enterprise of the English nation, 
 directed to this inquiry, has been the present sea-going steam-ship. 
 
 * For a more developed notice of American Steam Navigation, see 
 Railway EdAomy, chap, xvi., and Museum, vol. ii. p. 17. 
 
 W 12 115 
 
STEAM NAVIGATION. 
 
 4. In the quarter of a century which elapsed between 1812 
 and 1837 steam-navigation made a steady and continuous, but not 
 a sudden progress. The first lines of steamers were established 
 naturally between the ports of England and the nearest sea-ports 
 of Ireland on the one side, and France on the other. The length 
 of each unbroken passage was then regarded as the great difficulty 
 of the project. Thus steamers were established between Holyhead 
 and Dublin, and between Dover and Calais, long before projectors 
 ventured to try them between Dublin and Liverpool, or between 
 London and the Low Countries. 
 
 After some years' experience, however, and the consequent 
 improvement of the marine engine, passages of greater length 
 were attempted with success. Lines of steamers were established 
 first between more distant parts of the United Kingdom ; as, for 
 example, between London and Edinburgh, and between Dublin, 
 Liverpool, and Glasgow. At a later period still longer trips 
 became practicable, and lines of steamers were established between 
 the United Kingdom and the Mediterranean ; touching, however, 
 for fuel at the peninsular ports, such as Corunna, Lisbon, and 
 Gibraltar. 
 
 During this period, also, a fleet of steamers was constructed by 
 government for post-office purposes, and a steam navy was gra- 
 dually created, among which were found ships of large tonnage 
 and considerable power. 
 
 5. At length, in the year 1836, a project, then considered as a 
 startling one, was first announced, to supersede the far-famed New 
 York and Liverpool packet-ships, by a magnificent establishment 
 
 of STEAM- SHIPS, 
 
 These vessels were to sustain a constant, regular, and rapid 
 communication between the New and Old World. They were to 
 be the great channel for commerce, intelligence, and social inter- 
 course, between the metropolis of the West and the vast marts of 
 the United Kingdom ; they were, in a word, to fulfil, not only all 
 the functions which for half a century had been so admirably dis- 
 charged by the packet-ships, but to do so with expedition increased 
 in a threefold proportion at the least. Such an announcement 
 could not fail to captivate the public. The results to be anti- 
 cipated were so obvious, so grand, and must be attended with 
 effects so widely spread, that all persons of every civilised nation 
 at once felt and acknowledged their importance. The announce- 
 ment of the project was accordingly hailed with one general shout 
 of acclamation. 
 
 Some, who, being conversant with the actual condition of the 
 art of steam-engineering as applied to navigation, and aware of 
 various commercial conditions which must affect the problem, and 
 116 
 
TRANSATLANTIC STEAMERS. 
 
 were enabled to estimate calmly and dispassionately the difficulties 
 and drawbacks, as well as the advantages, of the undertaking, 
 entertained doubts which clouded the brightness of their hopes, 
 and warned the commercial word against the indulgence of too 
 sanguiue anticipations, of the immediate and unqualified realisa- 
 tion of the project. They counselled caution and reserve against 
 an improvident investment of extensive capital, in schemes which 
 could stiU be only regarded as experimental, and which might 
 prove its grave. But the voice of remonstrance was drowned 
 amid the enthusiasm excited, by the promise of an immediate 
 practical realisation of a scheme so grand. The keel of the Great 
 "Western was laid ; an assurance was given that the seasons would 
 not twice run through their changes, before she would be followed 
 by a splendid line of vessels, which should consign the packet- 
 ships to the care of the historian as " things that were." 
 
 6. It cannot be seriously imagined, that any one who had been 
 conversant with the past history of steam-navigation, could 
 entertain the least doubt of the abstract practicability of a steam- 
 vessel making the voyage between Bristol and New York. 
 
 A vessel having as her cargo a couple of hundred tons of coals 
 would, cceteris paribus, be as capable of crossing the Atlantic as a 
 vessel transporting the same weight of any other cargo. A 
 steam- vessel of the usual form and construction would, it is true, 
 labour under comparative disadvantages, owing to obstructions 
 presented by her paddle-wheels and paddle-boxes; but still it 
 would have been preposterous to suppose that these impediments 
 could have rendered her passage to New York impracticable. 
 
 7. But, independently of these considerations, it was a well- 
 known fact, that, long antecedent to the epoch now adverted to, 
 the Atlantic had actually been crossed by the steamers Savannah 
 and Cura9oa. Nevertheless a statement was not only widely 
 circulated, but generally credited, that I had publicly asserted 
 that a steam voyage across the Atlantic was physical impos- 
 sibility ! " 
 
 Although this erroneous statement has been again and again 
 publicly contradicted through various organs of the press, it con- 
 tinues nevertheless to be repeated. I shall therefore take this 
 opportunity once more to put on record, what I really did state on 
 the occasion, on which I am reported to have affirmed that the 
 Atlantic steam voyage was a physical impossibility. 
 
 8. Projects had been started in the year 1836 by two different 
 and opposing interests, one advocating the establishment of a line 
 of steamers to ply between the west coast of Ireland and Boston, 
 touching at Halifax ; and the other a direct line, making an un- 
 interrupted trip between Bristol and New York. In the year 
 
 iir 
 
STEAM NAVIGATION. 
 
 1836, on the occasion of the meeting of the British Association in 
 Dublin, I had advocated the former of these projects. 
 
 9. On the occasion of the next meeting in 1837 at Bristol, I 
 again urged its advantages, and by comparison discouraged the 
 project of a direct line between Bristol and New York. When I 
 say that I advocated one of these projects, it is needless to add 
 that the popular rumour, that I had pronounced the Atlantic 
 voyage impracticable, is utterly destitute of foundation. But I 
 am enabled to offer more conclusive proofs than this, that, so far 
 from asserting that the Atlantic voyage by steam was impossible, 
 I distinctly affirmed the contrary. 
 
 The Times newspaper sent a special reporter to attend the 
 meeting at Bristol, and more particularly to transmit a report of 
 the expected discussion on the Atlantic steam voyage, which at 
 the moment excited much interest. 
 
 10. The meeting took place on the 25th, and the report ap- 
 peared in the Times of the 27th of August. From that report I 
 extract the following ; — 
 
 Dr. Lardner said he would beg of any one, and more espe- 
 cially of those who had a direct interest in the inquiry, to dismiss 
 from their minds all previously-formed judgments about it, and 
 more especially upon this question, to he guarded against the con- 
 clusions of mere theory, for if ever there was one point in practice 
 of a commercial nature which, more than another, required to be 
 founded on experience, it was this one of extending steam-naviga- 
 tion to voyages of extraordinary length. He was aware that 
 since the question had arisen, it had been stated that his own 
 opinion was averse to it. This statement was totally wrong, but 
 he did feel that great caution should be used in the adoption of 
 the means of carrying the project into effect. Almost all depended 
 on the first attempt, for a failure would much retard the ultimate 
 consummation of the project. 
 
 Mr. Scott Russell said that he had listened with great delight 
 to the lucid and logical observations they had just heard. He 
 would add one word. Let them try this experiment, with a view 
 only to the enterprise itself, but on no account try any new boiler 
 or other experiment, but to have a combination of the most 
 approved plans that had yet been adopted. 
 
 " After some observations from Messrs. Brunei and Field, 
 Dr. Lardner, in reply, said, that he considered the voyage prac- 
 ticable, but he wished to point out that which would remove the 
 possibility of a doubt, because if the first attempt failed it would 
 cast a damp upon the enterprise, and prevent a repetition of the 
 attempt," 
 
 118 
 
MISREPEESENTATION OF DR. LARDNER'S VIEWS. 
 
 Such, was the report of the Times of the speech in which I 
 was afterwards, and have ever since heen, represented as having 
 declared a steam voyage across the Atlantic a mechanical im- 
 possibility ! * 
 
 11. What I did affirm and maintain in 1836-7 was, that the 
 long sea voyages by steam which were contemplated, could not at 
 that time he maintained with that regularity and certainty which 
 are indispensable to commercial success, by any revenue which 
 could be expected from traffic alone, and that, without a govern- 
 ment subsidy of a considerable amount, such lines of steamers, 
 although they might be started, could not be permanently 
 maintained. 
 
 12. Now let us see what has been the practical result. 
 
 Eight steam-ships, including the Great Western, were, soon 
 after the epoch of these debates, placed upon the projected line 
 between England and New York ; the Sirius, the Royal William, 
 the Great Liverpool, the United States, f the British Q-ueen, the 
 President, the Great Western, and the Great Britain. 
 
 The Sirius was almost immediately withdrawn; the Royal 
 William, after a couple of voyages, shared the same fate ; the 
 Great Liverpool, in a single season, involved her proprietors in a 
 loss of 6000/., and they were glad to remove her to the Mediter- 
 ranean station. The proprietors of the British Q,ueen, after 
 sustaining a loss which is estimated at little less than 100000/., 
 sold that ship to the Belgian government. The United States 
 was soon transferred, like the Great Liverpool, to the Mediter- 
 ranean trade. The President was lost. The Great Western, as 
 is well known, after continuing for some time to make the voyage 
 in the summer months, being laid by during the winter, and after 
 involving her proprietors in a loss of unknown and unacknow- 
 ledged amount, was sold. Of the Great Britain, the fate is well 
 known. 
 
 Thus, it appears, in fine, that after the lapse of nearly fourteen 
 years, notwithstanding the great improvements which took place 
 in steam navigation, the project advanced at Bristol, and there 
 pronounced by me to be commercially impracticable, signally failed. 
 
 13. Meanwhile another project, based upon the conditions which 
 I had indicated as essential to the permanence and success of the 
 enterprise, was started. 
 
 Mr. Samuel Cunard, a Canadian, who had extensive experience 
 
 * Notices of this speech, substantially the same, appeared in the 
 Edinburgh Review, the Monthly Chronicle, and other periodicals of that 
 date. 
 
 This vessel was not actually placed on the line, but was prepared hx 
 it. She was afterv/ards called the Oriental. 
 
 119 
 
STEAM NAVIGATION. 
 
 in maritime affairs, being associated with some large capitalists 
 who had confidence in his sagacity and skill, laid before the 
 British government a project for a line of Post-office steamers, to 
 ply between Liverpool and Boston, touching at Halifax. But 
 Mr. Cunard insisted strongly on the necessity of providing a 
 considerable fleet of steamers, to ensure that permanence and 
 regularity which were indispensable to the success of the project. 
 He demonstrated that the magnitude of the capital it must involve, 
 and the vast expenditure attending its maintenance, were such as 
 could not be covered by any commercial returns to be expected 
 from it, and that, consequently, it could only be sustained by a 
 liberal subsidy to be furnished by the government. After much 
 negotiation, it was agreed to grant him an annual subsidy of 
 60000Z., upon which condition the enterprise was commenced. 
 Mr. Cunard, however, had hardly embarked in it, before it became 
 evident that this grant was insufficient, and it was soon increased 
 to 100000/. per annum. Further experience proved that even 
 this was insufficient to enable Cunard and his associates to 
 maintain the communication in a satisfactory and efficient manner, 
 and the annual subvention was in fine raised to its present amount, 
 that is to say, 145000/. sterling per annum. 
 
 14. Thus supported, the communication was in 1851 main- 
 tained throughout the year. During the four winter months, 
 December, January, February, and March, there were two de- 
 partures per month from each side, and during the eight other 
 months of the year there was a departure once a week, making a 
 total of forty-four departures from each side, or forty-four voyages 
 going and returning. 
 
 These voyages make a total distance sailed of 272800 geogra- 
 phical miles within the year. The subsidy, therefore, amounts to 
 ten shillings and eightpence per mile sailed. 
 
 Since the epoch here referred to, steam-navigation has, as is 
 well known, undergone great improvements, and its powers have 
 been proportionally extended. The arrangements of this and 
 other lines of ocean navigation have accordingly undergone, and 
 continue to undergo, modifications having the effect of increasing 
 the frequency and extending the lengths of the trips. 
 
 15. Soon after the Cunard line of steamers commenced opera- 
 tions, it was proposed to establish, with government support, a 
 transatlantic line of steamers communicating between Great 
 Britain and its West India colonies. Ultimately the present 
 "West India Steam-Packet Company was establislied, and obtained 
 from the government a subvention greater still in amount than 
 had been granted to the Cunard Company. The amount of this 
 annual grant was 240000/. 
 
 120 
 
CUNAED LINE. 
 
 16. Great as the progress of steam-navigation lias teen within 
 the last quarter of a century, much still remains to be accom- 
 plished, before that vast agent of transport can be regarded as 
 having been pushed to the limit of its powers. Its superior speed, 
 regularity, and certainty, comparatively with sailing-vessels, have 
 naturally first attracted to it passengers, despatches, and certain 
 descriptions of merchandise to which expedition is important, and 
 which can bear a high rate of freight. The mechanical conditions 
 which ensure expedition in long voyages, exclude, to a great 
 extent, the transport of general merchandise ; for a large part of 
 the tonnage of the vessel is occupied by the machinery and fuel. 
 The heavy expenses, therefore, of the construction and mainte- 
 nance of these vessels, must be defrayed by appropriating the 
 profitable tonnage to those objects of transport alone which will 
 bring the highest rate of freight. While the steamer, therefore, 
 has allured from the sailing-vessel the chief part of the passenger 
 traffic, the mails altogether, parcels, and some few objects of 
 general traffic, the latter still continues in undisturbed possession 
 of the transport business of general commerce. 
 
 The next step in the improvement of the art must therefore be 
 directed to the construction of another class of steam- vessels, 
 which shall bear to the present steam-ships the same relation 
 which the goods-trains, on the railway, bear to the passenger- 
 trains. As in the case of these goods-trains, expedition must be 
 sacrificed to reduce the cost of transport to the limit which shall 
 enable the merchandise to bear the freight. If the steamer for 
 the general purposes of commerce can be made to exceed the 
 sailing-vessel, in anything approaching to the ratio by which the 
 goods-train on the railway exceeds the waggon or canal-boat, we 
 shall soon see the ocean covered with such steamers, and the 
 sailing-vessel will pass from the hands of the merchant to those 
 of the historian. 
 
 17. To render steamers capable of attaining these ends, it will 
 be evidently advisable to adopt measures, to combine the qualities 
 of a sailing-vessel with those of a steamer. The ships must 
 possess such steaming power as may give them that increased 
 expedition, regularity, and punctuality, which, in the existing 
 state of the arts, can only be obtained through that agency ; but 
 it is also important that they should accomplish this without 
 robbing them, to any injurious extent, of their present capability 
 of satisfying the wants of commerce. 
 
 18. In an early edition of my treatise on the Steam-Engine, 
 published long before screw steam-vessels had attained the state 
 of perfection to which they have now arrived, I stated that no ex- 
 pedient was more likely to accomplish this, than one which would 
 
 121 
 
STEAM NAVIGATION. 
 
 have for its object tlie removal of the paddle-wheels now generally 
 used, and the substitution of some description of subaqueous pro- 
 peller. A great reduction in the dimensions of the machinery, 
 and the surrender to the uses of commerce of that invaluable space 
 which it now occupies within the vessel, are also essential. It is 
 incumbent on the engineer who assumes the high responsibility of 
 the superintendence of such a project, to leave the ship in the full 
 and unimpaired enjoyment of its functions as a sailing-vessel. 
 Let him combine, in short, the agency of steam with the undi- 
 minished nautical power of the ship. Let him celebrate the 
 marriage of the steam-engine with the sailing-vessel. If he 
 accomplish this with the skill and success of which the project is 
 susceptible, he may fairly hope that his name will go down to 
 posterity as a benefactor of mankind, united with those of Fulton 
 and Watt. 
 
 The actual progress of mechanical science encourages us to hope, 
 that the day is fast approaching when such ideas will be realised 
 — when we shall behold a great highway cut across the wide 
 Atlantic, not as now, subserving to those limited ends, the 
 attainment of which will bear a high expense, but answering all 
 the vast and varied demands of general commerce. Ships which 
 would serve the purposes we have here shadowed out, can never 
 compete in mere speed with vessels in which cargo is nothing, 
 expense disregarded, and expedition everything. Be it so. 
 Leave to such vessels their proper functions ; let them still enjoy 
 to some extent the monopoly of the most costly branches of 
 traffic, subsidised as they are by the British treasury. Let the 
 commercial steam-ships, securing equal regularity and punctu- 
 ality, and probably more frequent despatch, be content with 
 somewhat less expedition. This is consistent with all the analo- 
 gies of commerce. 
 
 There is another consideration which ought not to be omitted. 
 In all great advances in the arts of life, extensive improvements 
 are at first attended with individual loss of greater or less amount. 
 The displacement of capital is almost inevitably attended with 
 this disadvantage. It is the duty, therefore, of the scientific 
 engineer, in the arrangement and adoption of his measures, to 
 consider how these objects may be best attained with the least 
 possible injury to existing interests. To accomplish this will not 
 only be a benefit to the public, but will materially facilitate the 
 realisation of his own objects, by conciliating in their favour those 
 large and powerful interests, whose destruction would be other- 
 wise menaced by them. If, then, in the present case, it is found 
 practicable with advantage to introduce into the present sailing- 
 ships, more especially into those most recently constructed, the 
 122 
 
SCEEW STEAMEES. 
 
 agency of steam, a very important advantage will be gained for 
 the public, and the almost unanimous support and countenance of 
 the commercial community will be secured. 
 
 19, To attain the objects here developed, it will be evidently in- 
 dispensable to remove those impediments, which at once disfigure 
 the appearance and destroy the efficiency of the sailing qualities of 
 the ship, by the enormous and unsightly excrescences projecting 
 from the sides in the shape of paddle-wheels, and the wheel-houses 
 or paddle-boxes, as they are called. These appendages are attended 
 with many evils, the least of which is perhaps the impediment 
 which they present to the progress of the ship. 
 
 But the form, magnitude, and position of the propelling ma- 
 chinery, is far from being the only obstacle to the full success of 
 the present steam-vessels, when directed to the general purposes of 
 commerce. The engines themselves, and the boilers, from which 
 the moving power proceeds, and the fuel by which they are worked, 
 occupy the very centre of the vessel, and engross the most valuable 
 part of the tonnage. The chimney, which gives efficacy to the 
 furnaces, is also an unsightly excrescence, and no inconsiderable 
 obstruction. 
 
 When long ocean-voyages are contemplated, such as those be- 
 tween New York and the ports of England, there is another serious 
 obstacle, which is especially felt in the westward trip, because of 
 the prevalence of adverse winds. When the vessel starts on its 
 long voyage, it is necessarily laden with a large stock of fuel, 
 which is calculated to meet, not merely the average exigencies of 
 the voyage, but the utmost extremity of adverse circumstances of 
 wind and weather to which it can by possibility be exposed. This 
 fuel is gradually consumed upon the voyage ; the vessel is propor- 
 tionally lightened, and its immersion diminished. If its trim be 
 so regulated that the immersion of its wheels at starting be such, 
 as to give them complete efficiency, they may, before the end of 
 the voyage, be almost if not altogether raised out of the water. 
 If, on the other hand, the efficiency of propulsion in the latter 
 part of the voyage be aimed at, they must have such a depth at 
 its commencement as to impair in a serious degree their propelling 
 effect, and to rob the vessel of its proper speed. Under such cir- 
 cumstances, there is no expedient left but compromise. The vessel 
 must start with too great and arrive with too little immersion. 
 There is no alternative, save to abandon altogether the form and 
 structure of the present machinery, and to awaken the inventive 
 genius of the age to supply other mechanical expedients, which 
 shall not. be obnoxious to these objections. 
 
 In fine, then, we look to the improvement of auxiliary steam 
 power, ana the extended use of submerged propellers, as the means 
 
 123 
 
STEAM NAVIGATION. 
 
 which, in the existing state of the art of steam-navigation, are 
 most likely to extend the benefits of that agent of transport to 
 general commerce. 
 
 20. If the form and structure of paddle-wheel steam-vessels be 
 obaoxious to these many serious objections, when considered with 
 reference to the purposes of general commerce, they are still more 
 objectionable when considered with reference to the purposes of 
 national defence. It is undoubtedly a great power with which to 
 invest a vessel of war, to be able to proceed at will, in spite of 
 the opposition of wind or tide, in any direction which may seem 
 most fit to its commander. Such a power would have surpassed 
 the wildest dreams of the most romantic and imaginative naval 
 commander of the last century. To confer upon the vessels of a 
 fleet the power immediately, at the bidding of the commander, to 
 take any position that may be assigned to them relatively to the 
 enemy, or to run in and out of a hostile port at pleasure, or fly 
 with the rapidity of the wind past the guns of formidable forts, 
 before giving them time to take efifect upon them — are capabilities 
 which must totally revolutionise all the established principles of 
 naval tactics. But these powers at present are not conferred upon 
 steam-ships, without important qualifications and serious draw- 
 backs. The instruments and machinery from which they are 
 immediately derived are, unfortunately, exposed in such a manner 
 as to render the exercise of the powers themselves hazardous in 
 the extreme. It needs no profound engineering knowledge to 
 perceive that the paddle-wheels are eminently exposed to shot, 
 which, taking efiect, would altogether disable the vessel, and 
 leave her at the mercy of the enemy ,; and the chimney is even 
 more exposed, the destruction of which would render the vessel a 
 prey to the enemy within itself in the shape of fire. But besides 
 these most obvious sources of exposure in vessels of the present 
 form intended as a national defence, the engines and boilers 
 themselves, being more or less above the water line, are exposed 
 so as to be liable to be disabled by shot. 
 
 A war steamer, to be free from these objections, should be pro- 
 pelled by subaqueous apparatus. Her engines, boilers, and all 
 other parts of her machinery should be below the water-line. Her 
 fuel should be hard coal, burning without visible smoke, so that 
 her approach may not be discoverable from a distance. Her fur- 
 naces might be worked by blowers, so that the chimney might be 
 dispensed with, and thus its liability to be carried away by shot 
 removed. 
 
 21. The policy of the British government has been to rely on the 
 commercial steam navy as a means of national defence, in the 
 event of the sudden outbreak of war. By the evidence given 
 
 124 
 
WAR STEAMERS. 
 
 before a committee of the House of Commons in 1850, and tlie 
 report founded thereupon, it appeared that commercial steamers 
 in general are capable of war service, with no other previous 
 alteration or preparation than such as are easily practicable and 
 expeditiously executed. It was shown that all steamers of 400 
 tons and upwards would be capable, with some additional strength- 
 ening, to carry such pivot guns as are used in war-steamers, and 
 that there are few mercantile steamers of any size, winch might 
 not carry an armament such as would render them useful in case 
 of an emergency. 
 
 22. The principle on which the steam-engine is applied to the 
 propulsion of ships is the same as that by which oars act in pro- 
 pelling boats. In both cases the propelling instruments having a 
 point or points of reaction on the vessel, are made to drive a mass 
 of water backwards, and the moving force, or momentum, thus 
 imparted to the water from stem to stern, is necessarily attended 
 with a reaction from stern to stem, which, taking effect on the 
 vessel, gives it a corresponding progressive motion. 
 
 By the well-known mechanical principle of the composition and 
 resolution of force, it can be demonstrated that whatever force 
 may be imparted to the water by the propeller, such force can be 
 resolved into two elements, one of which is parallel, and the 
 other in a plane at right angles to the keel. The former 
 alone can have a propelling effect, and since the latter is wholly 
 ineffective, the propeller should always be so constructed that its 
 whole force, or at least the chief part of it, shall be employed in 
 driving the water in a direction parallel to the keel from stem to 
 stern. 
 
 23. The mechanical expedients by which the power of steam is 
 rendered available for the propulsion of vessels are very various, 
 both as regards the form of the engine which acts upon the pro- 
 peller, and the form of the propeller itself. 
 
 In all cases hitherto reduced to practice, the propeller is a wheel 
 fixed upon a horizontal shaft, to which the engine imparts a 
 motion of continued rotation. The wheel is so constructed that 
 when it revolves it imparts to a volume of water, more or less 
 considerable, a motion either directly backwards, or one whose 
 principal component has that direction. The greater the pro- 
 portion which this principal component has to the entire force 
 exercised by the propeller, the more effective it will be. 
 
 24. The propellers hitherto practically applied in steam-naviga- 
 tion are of two kinds, called paddle-wheels and screws. 
 
 The shaft of the paddle-wheels is fixed horizontally across the 
 vessel, and consequently at right angles to the direction of the 
 keel. 
 
 125 
 
STEAM NAVIGATION. 
 
 The sliaft of the screws is placed horizontally in the vessel 
 parallel to the keel, and directly above it. 
 
 The faces of the paddle-wheels look sideways and are conse- 
 quently parallel to the keel. 
 
 The faces of the screws look sternwards, and are consequently 
 at right angles to the keel. 
 
 25. The paddle-wheels are in pairs one at each side of the vessel 
 and outside the hull, being supported on the projecting ends of 
 the paddle-shaft, and covered by large semi-cylindrical drums 
 called paddle-boxes. 
 
 The screws are generally single wheels, within the vessel under 
 its hull, and placed near the stern. 
 
 Only the lower parts of the paddle-wheels are immersed. The 
 screws are altogether submerged. 
 
 26. The paddle-shaft being carried on each side beyond the 
 timbers of the vessel, the wheels supported by it and revolving 
 with it, are usually constructed like undershot water-wheels, 
 having attached to their rims a number of flat boards called 
 paddle-hoards. As the wheels revolve, these paddle-boards strike 
 the water, driving it in a direction contrary to that in which it is 
 intended the vessel should be propelled. On the paddle-shaft 
 two cranks are constructed, similar to the crank on the axle of 
 the fly-wheel of a stationary engine. These cranks are generally 
 placed at right angles to each other, so that when either is in its 
 highest or lowest position the other shall be horizontal. They 
 are driven by two steam-engines, which are usually placed in the 
 hull of the vessel below the paddle-shaft. In the earlier steam- 
 boats a single steam-engine was used, and in that case the unequal 
 action of the engine on the crank was equalised by a fly-wheel. 
 This, however, has been long since abandoned in European vessels, 
 and the use of two engines is now almost universal. By the relative 
 position of the cranks it will be seen, that when either crank is at 
 its dead point the other will be in one of the positions most favour- 
 able to its action, and in all intermediate positions, the relative 
 efficiency of the cranks will be such as to render their combined 
 action very nearly uniform. 
 
 The steam-engines used to impel vessels may be either con- 
 densing engines, similar to those of Watt, and such as are used in 
 manufactures generally, or they may be non-condensing and high- 
 pressure engines, similar in principle to those used on railways. 
 Low-pressure condensing engines are, however, universally used for 
 marine purposes in Europe, and to a great extent in the United 
 States. In the latter country, however, high-pressure engines are 
 also used in some of the river steamers. 
 
 27. The arrangement of the parts of a marine engine differs in 
 
 126 
 
MARINE ENGINES. 
 
 some respects from that of a land engine. The limitation of space, 
 which is unayoidable in a vessel, renders greater compactness 
 necessary. The paddle-shaft on which the cranks to be driven by 
 the engine are constructed being very little below the deck of the 
 vessel, the beam, if there be one, and connecting rod could not be 
 placed in the position in which they usually are in land engines, 
 without carrying the machinery to a considerable elevation above 
 the deck. This is done in the steam-boat engines used on the 
 American rivers ; but it would be inadmissible in steam-boats in 
 general, and more especially in sea-going steamers. The connect- 
 ing rods, therefore, instead of being presented downwards towards 
 the cranks which they drive, must, in steam- vessels, be presented 
 upwards, and the impelling force be received from below. If, 
 under these circumstances, the beam were in the usual position 
 above the cylinder and piston-rod, it must necessarily be placed 
 between the engine and the paddle-shaft. This would require a 
 depth for the machinery which would be incompatible with the 
 magnitude of the vessel. The beam, therefore, of marine engines, 
 instead of being above the cylinder and piston, is placed below 
 them. To the top of the piston rods, cross-pieces are attached, 
 of greater length than the diameter of the cylinders, so that their 
 extremities shall project beyond the cylinders. To the ends of 
 these cross-pieces are attached by joints the rods of a parallel 
 motion : these rods are carried downwards, and are connected 
 with the ends of two beams below the cylinder, and placed on 
 either side of it. The opposite ends of these beams are con- 
 nected by another cross-piece, to which is attached a connecting 
 rod, which is continued upwards to the crank-pin, to which it 
 is attached, and which it drives. Thus the beam, parallel motion, 
 and connecting rod of a marine engine, are similar to those of a 
 land engine, only that they are turned upside down ; and in con- 
 sequence of the impossibility of placing the beam directly over the 
 piston rod, two beams and two systems of parallel motion are pro- 
 vided, one on each side of the engine, acted upon by, and acting 
 on the piston rod and crank by cross-pieces.* 
 
 The proportion of the cylinders differs from that usually ob- 
 served in land engines for like reasons. The length of the 
 cylinder of land engines is generally greater than its diameter, 
 in the proportion of about two to one. The cylinders of marine 
 engines are, however, commonly constructed with a diameter 
 greater than their length. In proportion, therefore, to their 
 power their stroke is shorter, which infers a corresponding short- 
 
 * We must assume that the reader of the present Tract has already 
 rendered himself familiar with the several Tracts on Steam and the Steam 
 Engine, already published in the Museum. 
 
 127 
 
STEAM NAVIGATION. 
 
 ness of crank and a greater limitation of play of all tho moving 
 parts in the vertical direction. The valves and the gearing by 
 wliich they are worked, the air-pump, the condenser and other 
 parts of the marine engines, do not differ in principle from those 
 already described in land engines. 
 
 These arrangements will bo more clearly understood by 
 reference to hg. 1, in which is represented a longitudinal 
 section of one of the many varieties of beam engine, with its 
 boiler as placed in a steam-vessel. The sleepers of oak, sup- 
 porting the engine, are represented at X, the base of the engine 
 being secured to these by bolts passing through them and the 
 bottom timbers of the vessel ; s is the steam-pipe leading from 
 the steam-chest in the boiler to the slides c, by which it is 
 admitted to the top and bottom of the cylinder. The condenser is 
 represented at B, and the air-pump at e. The hot well is seen at 
 F, from which the feed is taken for the boiler ; l is the piston-rod 
 connected by the parallel motion a, with the beam ii, working on 
 a centre K, near the base of the engine. The other end of the 
 beam i drives the connecting rod m, which extends upwards to 
 the crank, which it works upon the paddle-shaft o. q r is tho 
 framing by which the engine is supported. The beam here exhi- 
 bited is sho^vn on dotted lines as being on the further side of the 
 engine. A similar beam similarly placed, and moving on the 
 same axis, must be understood to be at this side connected with 
 the cross-head of the piston in like manner by a parallel motion, 
 and with a cross-piece attached to the lower end of the connecting 
 rod and to the opposite beam. The eccentric which works the 
 slides is placed upon the paddle-shaft o, and the connecting arm 
 which drives the slides may be easily detached when the engine 
 reciuires to be stopped. The section of the boiler, grate, and tlues 
 is represented at w u. The safety-valve y is enclosed beneath a 
 pipe carried up beside the chimney, and is inaccessible to the 
 engine man ; h are the cocks for blowing the salted water from 
 the boiler, and 1 1 the feed-pipe. 
 
 128 
 
Fig. 2. — VORM AND POSITION OF THE SCREW. 
 
 STEAM NAVIGATION. 
 
 CHAPTER II. 
 
 28. Arrangement of the engine-room ; governor and other regulating parts 
 omitted. — 29. Flue boilers and tubular boilers, — 30. Construction of 
 flue boilers. — 31. Tubular boilers. — 32. Indications of engineering 
 ignorance. — 33. Number and dimensions of tubes. — 34. Incrustation 
 produced by sea water. — 35. Hydrometric indicators. — 37. Thermo- 
 metric indicators. — 38. Seaward's contrivance. — 39. Brine-pumps. — 
 40. Blowing out. — 41. To detach the scale. — 42. Effect of corrosion. 
 — 43. Efficiency and economy of fuel. — 44. Coating the boiler and 
 pipes with felt. 
 
 28. The general arrangement of the engine-room of a steam- 
 vessel is represented in fig. 3, page 131. 
 
 The nature of the efiect required to be produced by marine 
 engines, does not render either necessary or possible that great 
 regularity of action, which is indispensable in a steam-engine 
 applied to the purposes of manufacture. The agitation of the 
 surface of the sea will cause the immersion of the paddle-wheels 
 to be subject to great variation, and the resistance produced by 
 the water to the engine will undergo a corresponding change. 
 The governor, therefore, and other parts of the apparatus, con- 
 trived for giving to the engine that great regularity required in 
 manufactures, are omitted in nautical engines, and nothing is 
 introduced save what is necessary to maintain the machine in its 
 full working efficiency. . 
 
 Marine boilers are constructed in forms so infinitely various, 
 that, in a notice so brief and popular as the present, we can only 
 indicate some of their more general arrangements, and aid the 
 
 Lardner's Museum of Soieitce. e 129 
 
 No. 122. 
 
130 
 
MARINE BOILERS. 
 
 explanation by figures representing examples of particular classes 
 of them. 
 
 29. To save space, they are constructed so as to produce the 
 necessary quantity of steam, within the smallest possible dimen- 
 sions. With this view a more extensive surface in proportion to 
 the capacity of the boiler is exposed to the action of the fire. The 
 flues, by which the flame and heated air are conducted to the 
 chimney, are generally so constructed that the heated air issuing 
 from the furnaces may be made to pass through the boiler, either 
 
 Fig. 3. 
 
 by a series of oblong narrow passages with flat sides, called fims^ 
 or by a multitude of tubes of small diameter, the one and the 
 other leading from the furnaces to the base of the chimney, and 
 being everywhere below the level of the water in the boiler. The 
 former are called jlue hollers, and the latter tubular boilers. 
 
 30. In the former class of boilers the flues are so formed as to 
 traverse the boiler backwards and forwards several times before 
 they terminate in the chimney. Such an arrangement renders the 
 expense of the boilers greater than that of common land boilers, 
 but their steam-producing power is greatly augmented. Experi- 
 ments made by Mr. Watt, at Birmingham, proved that such boilers 
 with the same consumption of fuel will produce, as compared with 
 
 k2 131 
 
STEAM NAVIGATION. 
 
 common land boilers, an increased evaporation in the proportion of 
 about three to two. 
 
 The form and arrangement of the water-spaces and flues in 
 flue boilers are infinitely various. The sections of such boilers 
 are exhibited in figs. 4, 5, 6. A section made by a horizontal 
 
 Fig. 4. 
 
 plane passing through the flues is exhibited in fig. 4. The 
 furnaces F communicate in pairs with the flues e, the air following 
 the course through the flues represented by the arrows. The flue E 
 passes to the back of the boiler, then returns to the front, then 
 
 Fig. 5. 
 
 132 
 
MAKINE BOILERS. 
 
 to the back again, and is finally carried back to the front, where 
 it communicates at c with the curved flue b, represented in the 
 transverse vertical section, fig. 5. This curved flue b finally 
 terminates in the chimney a. There are, in this case, three inde- 
 pendent boilers, each worked by two furnaces communicating with 
 the same system of flues ; and in the curved flues b, fig. 5, by 
 which the air is finally conducted through the chimney, are placed 
 three independent dampers, by means of which the furnace of 
 each boiler can be regulated independently of the other, and by 
 which each boiler may be separately detached from, communication 
 with the chimney. 
 
 A longitudinal section of the boiler, made by a vertical plane 
 extending from the front to the back, is given in fig. 6, where P, 
 as before, is the furnace, G the grate-bars sloping downwards 
 from the front to the back, H the fire-bridge, c the commencement 
 of the flues, and A the chimney. An elevation of the front of the 
 
 Kg. 6. 
 
 boiler is represented in fig. 7, showing two of the fire-doors closed 
 and the other two removed, displaying the position of the grate- 
 bars in front. Small openings are also provided, closed by proper 
 doors, by which access can be had to the under-side of the flues, 
 between the foundation timbers of the engine, for the purpose of 
 cleaning them. 
 
 Each of these boilers can be worked independently of the others. 
 By this means, when at sea, the engine may be worked by any 
 two of the three boilers, while the third is being cleaned and put 
 in order. 
 
 In the boilers here represented the flues are all upon the same 
 level, winding backwards and forwards without passing one above 
 the other. In other boilers, however, the flues, after passing 
 backwards and forwards near the bottom of the boiler, turn 
 
 133 
 
STEAM NAVIGATION. 
 
 upwards and pass backwards and forwards througli a level of the 
 water nearer its surface, finally terminating in the chimney. More 
 heating surface is thus obtained with the same capacity of boiler. 
 
 It is found in practice, that the most efficient parts of the fiue- 
 surface for the generation of steam, are those which are horizontal 
 
 Pig. r. 
 
 and at the upper parts of the flue, and the least efficient those 
 which are horizontal and at the lowest part, the efficiency of the 
 vertical sides being intermediate. 
 
 Since the flues are liable occasionally to become choked with 
 soot and ashes, it is necessary that their magnitude shall be 
 sufficient to allow a boy to enter them for the purpose of cleaning 
 them. 
 
 31. Tubular marine boilers are constructed on a principle pre- 
 cisely similar to that of locomotive boilers, described in a former 
 Tract. The flame and gaseous products of combustion, issuing 
 from the furnace at a very elevated temperature, pass through a 
 great number, sometimes several hundred, tubes of iron or brass, 
 of about three inches diameter, which traverse the boiler below the 
 level of the water in it, so that before they enter the chimney their 
 temperature is reduced to a comparatively low point, the heat 
 they thus lose being taken up by the water surrounding the tubes. 
 
 Flue boilers have the advantage over tubular boilers in being 
 cheaper and more durable. With the same evaporating power 
 they are however one-third larger and heavier, and consequently 
 occupy a greater portion of the tonnage, and produce, other 
 things being the same, a proportionally greater displacement, the 
 latter condition augmenting the resistance, and therefore either 
 diminishing the speed, or increasing the consumption of fuel. 
 134 
 
MAEINE BOILERS. 
 
 32. There cannot be a more striking proof of the ignorance of 
 general principles which prevails, respecting this branch of steam 
 engineering, than the endless variety of forms and proportions 
 which are adopted in the boilers and furnaces which are con- 
 structed, not only by different engineers but by the same 
 engineer, for steamers of like power and capacity, and even for 
 the same steamer at different times. Thus the original boilers 
 of the Great Western^ built for the New York and Bristol or 
 Liverpool voyage, were of the common flue sort. They were 
 subsequently taken out and replaced by tubular boilers. The 
 dimensions and relative proportions of these two sets of boilers, 
 thus supplied to the same vessel for the same voyage, differing as 
 completely one from the other as if they had been designed for 
 different vessels and different voyages. 
 
 On contemplating engineering proceedings, such as are exhibited 
 in the preceding table, it is impossible to deny that practical men 
 in such cases are groping in the dark, without the slightest benefit 
 from the light which they ought to derive, from the present 
 advanced state of physical science. 
 
 33. Tubular flue's have been in many steamers adopted in 
 preference to the flat and longer flues already described. In the 
 second set of boilers of the Great Western above mentioned, the 
 tubes were eight feet in length and three inches in diameter. In 
 the boilers of the steamer Ocean, which .are also tubular, the 
 following are the principal dimensions : — 
 
 Boilers : 
 
 Number . . 3 
 
 Length , . . 14 feet. 
 
 Breadth . . 191 feet. 
 Furnaces : 
 
 Number , . . 7 
 
 Length . . 7 feet. 
 
 Breadth . . . 2^ feet. 
 Tubes : 
 
 Material . . Iron. 
 
 Number . . 378 
 
 Length , . 9 feet 
 
 Diameter . . 3 5 inches. 
 Cylinders : 
 
 Number . . 2 
 
 Diameter . .66 inches. 
 
 Stroke . . 5^ feet. 
 Pressure of steam above 
 
 atmosphere . lbs. per in. 
 Consumption of coal 
 
 per hour . .18 cwt. 
 
 Among the more recent specifications of the machinery of marine 
 engines submitted to the Admiralty, are some in which the boilers 
 are traversed by nearly 2000 tubes of 3^ inches external diameter, 
 and five feet in length, giving a total heating surface of about 
 9000 square feet. 
 
 34. A formidable difficulty in the application of the steam- 
 engine to sea voyages has arisen from the necessity of supplying 
 the boiler with sea water instead of fresh water. The sea water 
 is injected into the condenser for the purpose of condensing the 
 
 135 
 
STEAM NAVIGATIOl^. 
 
 steam, and, mixed with the condensed steam, it is thence con- 
 ducted as feeding water into the boiler. 
 
 Sea water holds, as is well known, certain saline and alkaline sub- 
 stances in solution, the principal of which is muriate of soda, or 
 common salt. Ten thousand grains of pure sea water contain two 
 hundred and twenty grains of common salt, the remaining ingre- 
 dients being thirty- three grains of sulphate of soda, forty-two grains 
 of muriate of magnesia, and eight grains of muriate of lime. The 
 heat which converts pure water into steam does not at the same 
 time evaporate those salts which the water holds in solution. As 
 a consequence it follows, that, as the evaporation in the boiler is 
 continued, the salt, which was held in solution by the water 
 which has been evaporated, remains in the boiler, and enters into 
 solution with the water remaining in it. The quantity of salt 
 contained in sea water being considerably less than that which 
 water is capable of holding in solution, the process of evaporation 
 for some time is attended with no other effect, than to render the 
 water in the boiler a stronger solution of salt. If, however, this 
 process be continued, the quantity of salt retained in the boiler 
 having constantly an increasing proportion to the quantity of 
 water, it must at length render the water in the boiler a saturated 
 solution ; that is, a solution containing as much salt as, at the 
 actual temperature, it is capable of holding in solution. If, 
 therefore, the evaporation be continued beyond this point, the salt 
 disengaged from the water evaporated, instead of entering into 
 solution with the water remaining in the boiler, will be precipitated 
 in the form of sediment ; and if the process be continued in the 
 same manner, the boiler would at length become a mere salt-pan. 
 
 But besides the deposition of salt sediment in a loose form, some 
 of the constituents of sea water having an attraction for the iron 
 of the boiler, collect upon it in a scale or crust, in the same manner 
 as earthy matters, held in solution by spring water, are observed to 
 form and become incrusted on the inner surface of land-boilers 
 and of common culinary vessels. 
 
 The coating of the inner surface of a boiler by incrustation, and 
 the collection of salt sediment in its lower parts, are attended 
 with effects highly injurious to the materials of the boiler. The 
 crust and sediment thus formed within the boiler are almost non- 
 conductors of heat, and placed, as they are, between the water 
 contained in the boiler and the metallic plates which form it, they 
 obstruct the passage of heat from the outer surface of the plates 
 in contact with the fire, to the water. The heat, therefore, accu- 
 mulating in the boiler-plates so as to give them a much higher 
 temperature than the water within the boiler, has the effect of 
 softening them, and by the unequal temperature which will thus 
 X26 
 
EFFECTS OF SEA-WATER. 
 
 be imparted to tlie lower plates which, are incrusted, compared 
 with the higher parts which may not be so, an unequal expansion 
 is produced, by which the joints and seams of the boiler, are 
 loosened and opened, and leaks produced. 
 
 These injurious eifects can only be prevented by either of two 
 methods ; first, by so regulating the feed of the boiler that the 
 water it contains shall not be suffered to reach the point of 
 saturation, but shall be so limited in its degree of saltness that no 
 injurious incrustation or deposit shall be formed; secondly, by 
 the adoption of some method by which the boiler may be worked 
 with fresh water. This end can only be attained by condensing 
 the steam by a jet of fresh water, and working the boiler con- 
 tinually by the same water, since the supply of fresh water 
 sufS.cient for a boiler worked in the ordinary way, could never be 
 commanded at sea. 
 
 The method by which the saltness of the water in the boiler is 
 most commonly prevented from exceeding a certain limit, has 
 been to discharge from the boiler into the sea a certain quantity 
 of over- salted water, and to supply its place by sea water intro- 
 duced into the condenser through the injection-cock, for the 
 purpose of condensing the steam, this water being mixed with the 
 steam so condensed, and being, therefore, a weaker solution of 
 salt than common sea water. To effect this, cocks called blow- 
 off cocks are usually placed in the lower parts of the boiler, where 
 the over-salted, and therefore heavier, parts of the water collect. 
 The pressure of the steam and incumbent weight of the water in 
 the boiler force the.lowQr strata of water out through these cocks ; 
 and this process, called blowing out^ is, or ought to be practised at 
 such intervals as wiir prevent the water from becoming over- 
 salted. When the salted water has been blown out in this 
 manner, the level of the water in the boiler is restored by a feed 
 of corresponding quantity. 
 
 This process of blowing out, on the due and regular observance 
 of which the preservation and efficiency of the boiler mainly 
 depend, is too often left at the discretion of the engineer, who is, 
 in most cases, not even supplied with the proper means of ascer- 
 taining the extent to which the process should be carried. It is 
 commonly required that the engineer should blow out a certain 
 portion of the water in the boiler every two hours, restoring the 
 level by a feed of equivalent amount; but it is evident that the 
 sufficiency of the process, founded on such a rule, must mainly 
 depend on the supposition, that the evaporation proceeds always at 
 the same rate, which is far from being the case with marine boilers. 
 
 35. An indicator, by which the saltness of the water in the 
 boiler would always be exhibited, ought to be provided, and the 
 
 137 
 
STEAM NAVIGATION. 
 
 process of blowing out should be regulated by the indications of 
 that instrument. To blow out more frequently than is neoessary 
 is attended with a waste of fuel ; for hot water is thus discharged 
 into the sea while cold water is introduced in its place, and con- 
 sequently all the heat necessary to produce the difference of the 
 temperatures of the water blown, out, and the feed introduced, is 
 lost. If, on the other hand, the process of blowing out be observed 
 less frequently than is necessary, then more or less incrustation 
 and deposit may be produced, and the injurious effects already 
 described ensue. 
 
 36. As the specific gravity of water holding salt in solution is 
 increased with every increase of the strength of the solution, any 
 form of hydrometer capable of exhibiting a visible indication of 
 the specific gravity of the water contained in the boiler, would 
 serve the purpose of an indicator, to show when the process of 
 blowing out is necessary, and when it has been carried to a 
 sufficient extent. The application of such instruments, however, 
 would be attended with some practical difficulties in the case of 
 sea boilers. 
 
 37. The temperature at which a solution of salt boils under a 
 given pressure varies considerably with the strength of the 
 solution ; the more concentrated the solution is, the higher will 
 be its boiling temperature under the same pressure. A comparison, 
 therefore, of a steam-gauge attached to the boiler, and a ther- 
 mometer immersed in it, showing the pressure and the temperature, 
 would always indicate the saltness of the water ; and it would 
 not be difficult so to graduate these instruments as to make them 
 at once show the degree of saltness. 
 
 If the application of the thermometer be considered to be 
 attended with practical difficulty, the difference of pressures under 
 which the salt water of the boiler and fresh water of the same 
 temperature boil, might be taken as an indication of the saltness 
 of the water in the boiler, and it would not be difficult to construct 
 upon this principle a self-registering instrument, which would 
 not only indicate but record from hour to hour the degree of 
 saltness of the water. A small vessel of distilled water being 
 immersed in the water of the boiler would always have the tem- 
 perature of that water, and the steam produced from it com- 
 municating with a steam-gauge, the pressure of such steam would 
 be indicated by that gauge, while the pressure of the steam in 
 the boiler under which pressure the salted water boils might be 
 indicated by another gauge. The difference of the pressures 
 indicated by the two gauges would thus become a test, by which 
 the saltness of the water in the boiler would be measured. The 
 two pressures might be made to act on opposite ends of the same 
 138 
 
EEMEDIES. 
 
 coliunn of mercury contained in a siphon tube, and the difference 
 of the levels of the two surfaces of the mercury, would thus 
 become a measure of the saltness of the water in the boiler. A 
 self-registering instrument, founded on this principle, formed part 
 of the self-registering steam-log which I proposed to introduce 
 into steam- vessels some time since. 
 
 38. The Messrs. Seaward of Limehouse adopted, in some of 
 their engines, a method of indicating the saltness of the water, 
 and of measuring the quantity of salted water or brine discharged 
 by blowing out. A glass-gauge, similar in form to that already 
 described in land engines, is provided, to indicate the position of 
 the surface of the water in the boiler. In this gauge two hydro- 
 meter balls are provided, the weight of which in proportion to 
 their magnitude is such, that they would both sink to the bottom 
 in a solution of salt of the same strength as common sea water. 
 When the quantity of salt exceeds ^ parts of the whole weight 
 of the water, the lighter of the two balls will float to the top ; 
 and when the strength is further increased until the proportion 
 of salt exceeds £^ parts of the whole, then the heavier ball will 
 float to the top. The actual quantity of salt held in solution by 
 sea water in its ordinary state is ^ part of its whole weight ; 
 and when by evaporation the proportion of salt in solution has 
 become parts of the whole, then a deposition of salt commences. 
 With an indicator such as that above described, the ascent 
 of the lighter hydrometer ball gives notice of the necessity for 
 blowing out, and the ascent of the heavier may be considered as 
 indicating the approach of an injurious state of .saltness in the 
 boiler. 
 
 The ordinary method of blowing out the salted water from 
 a boiler is by a pipe, having a cock in it leading from the boiler 
 through the bottom of the ship, or at a point low down at its side. 
 Whenever the engineer considers that the water in the boiler has 
 become so salted, that the process of blowing out should com- 
 mence, he opens the cock communicating by this pipe with the 
 sea, and suffers an indefinite and uncertain quantity of water to 
 escape. In this way he discharges, according to the magnitude 
 of the boiler, from two to six tons of water, and repeats this at 
 intervals of from two to four hours, as he may consider to be 
 sufficient. If, by observing this process, he prevents the boiler 
 from getting incrusted during the voyage, he considers his duty 
 to be effectually discharged, forgetting that he may have blown 
 Out many times more water than is necessary for the preservation 
 of the boiler, and thereby produced a corresponding and unneces- 
 sary waste of fuel. In order to limit the quantity of water 
 discharged, Messrs. Seaward adopted the following method. In 
 
 139 
 
STEAM KAVIGATION. 
 
 fig. 8 is represented a transverse section of a part of a steam- 
 vessel; w is the water-line of the boiler, b is the mouth of a 
 blow-off pipe, placed near the bottom of the boiler. This pipe 
 rises to A, and turning in the horizontal direction, a c, is con- 
 ducted to a tank t, which contains exactly a ton of water. This 
 pipe communicates with the tank by a cock D, governed by a 
 lever h. When this lever is moved to d', the cock d is open, and 
 when it is moved to k, the cock d is closed. From the same tank 
 there proceeds another pipe e, which issues from the side of the 
 vessel into the sea, governed by a cock F, which is likewise put in 
 
 Fig. 8. 
 
 connection with the lever h, so that it shall be opened when the 
 kver H is drawn to the position f', the cock d' being closed in all 
 positions of the lever between k and f'. Thus, whenever the 
 cock F communicating with the sea is open, the cock d communi- 
 cating with the boiler is closed, and vice versa, both cocks being 
 closed when the lever is in the intermediate position z. By this 
 arrangement the boiler cannot, by any neglect in blowing off, be 
 kft in communication with the sea, nor can more than a ton 
 of water be discharged except by the immediate act of the 
 140 
 
BRINE-PUMPS. 
 
 engineer. The injurious consequences are tlms prevented which 
 sometimes ensue, when the hlow-off cocks are left open by any 
 neglect on the part of the engineer. When it is necessary to blow 
 off, the engineer moves the lever H to the position d'. The pres- 
 sure of the steam in the boiler on the surface of the water 
 forces the salted water or brine up the pipe b a, and through the 
 open cock c into the tank, and this continues until the tank is 
 filled : when that takes place, the lever is moved from the posi- 
 tion D' to the position p', by which the cock D is closed, and the 
 cock r opened. The water in the tank flows through the pipe e 
 into the sea, air being admitted through the valve v, placed at 
 the top of the tank, opening inwards. A second ton of brine 
 is discharged by moving the lever back to the position d', and 
 subsequently returning it to the position f' ; and in this way the 
 brine is discharged ton by ton, until the supply of water from the 
 feed which replaces it has caused both the balls in the indicator to 
 sink to the bottom. 
 
 39. A different method of preserving the requisite freshness of 
 the water in the boiler was adopted by Messrs. Maudslay and 
 Field. Pumps called hrine-pumps are put into communication 
 with the lower part of the boiler, and so constructed as to draw 
 the brine therefrom, and drive it into the sea. These brine- 
 pumps are worked by the engine, and their operation is constant. 
 The feed-pumps are likewise worked by the engine, and they bear 
 such a proportion to the brine-pumps that the quantity of salt 
 discharged in a given time in the brine is equal to the quantity 
 of salt introduced in solution by the water of the feed-pumps. 
 By this means the same actual quantity of salt is constantly 
 maintained an the boiler, and consequently the strength of the 
 solution remains invariable. If the brine discharged by the 
 brine-pumps contains ^ parts of salt, while the water introduced 
 by the feed-pumps contains only i part, then it is evident that 
 live cubic feet of the feeding- water will contain no more salt than 
 is contained in one cubic foot of brine. Under such circumstances 
 the brine-pumps would be so constructed as to discharge \ of the 
 water introduced by the feed-pumps, so that | of all the water 
 introduced into the boiler would be evaporated, and rendered 
 available for working the engine. 
 
 To save the heat of the brine, a method has been adopted in 
 the marine engines constructed by Messrs. Maudslay and Field, 
 similar to one which has been long practised in steam-boilers, and 
 in various apparatus for the warming of buildings. The current 
 of heated brine is conducted from the boiler through a tube 
 which is contained in another, through which the feed is intro- 
 duced. The warm current of brine, therefore, as it passes out, 
 
 141 
 
STEAM NAVIGATION. 
 
 iri parts a considerable portion of its heat to the cold feed which 
 ooiijes in ; and it is found that by this expedient the brine discharged 
 iuio the sea may be reduced to a temperature of about 100°. 
 
 This expedient is so effectual, that when the apparatus is pro- 
 perly constructed, and kept in a state of efficiency, it may be 
 regarded as nearly a perfect preventive against the incrustation, 
 and the deposition of salt in the boilers, and is not attended with 
 any considerable waste of fuel. 
 
 40. It is maintained hj some practical men, that the economy 
 of heat effected by brine-pumps, suoh as have been just described, 
 is more than counterbalanced by the risk which attends them, if 
 not accompanied by proper precautions. The pipes through which 
 the salted water is discharged are, it is said, apt to get choked, in 
 which case the pumps will necessarily cease to act, though they 
 appear to the engineer to do so ; and thus the water in the boiler 
 may become salted to any extent without the knowledge of the 
 engineer. "When the process of blowing out is executed in the 
 ordinary way, without brine-pumps, the engineer looks at his 
 water-gauge and keeps the blow-off cock open, until the water 
 level has fallen to the required point. Under these circumstances 
 there is a certainty of having discharged from the boiler a certain 
 quantity of salted water, a certainty which does not exist in the 
 case of a continuous discharge of water by brine-pumps. 
 
 Such expedients, therefore, it is contended, should always be 
 accompanied by some indicator, which shall show the degree of 
 saltness of the water in the boiler, such as we shall presently 
 explain. 
 
 41. In practice, if a marine boiler be regularly attended to, 
 and the salted water be discharged either by the common 
 method of bio wing-off cocks or by brine-pumps, or any other expe- 
 dient which shall impose the necessary limit on the degree of con- 
 centration of water in the boiler, the evil arising from incrustation 
 will be quite inconsiderable. 
 
 A scale will in all cases be formed on the inner surface of the 
 boilers, which must be removed from time to time when the vessel 
 is in port. The best method of effecting this is by lighting some 
 shavings, or other light and flaming combustible, in the furnaces 
 when the boilers are empty and the safety-valves open. The 
 expansion of the metal by the heat thus produced being greater 
 than that of the matter composing the scale, the latter will be 
 detached and will fall in pieces to the bottom of the boiler, from 
 which it can be withdrawn with the water at the man-holes. 
 
 In some cases, however, it will be preferable to detach the scale 
 by the hammer or chisel. 
 
 42. It is a great error to suppose that incrustation is either the 
 142 
 
ECONOMY OF FUEL. 
 
 sole or principal cause of the rapid destruction of marine boilers. 
 If it were so, it would necessarily happen that marine boilers in 
 which expedients are adopted by which fresh water is used, or 
 even those in which the process of blowing out has been regularly 
 observed, and in which the scale is detached before it is allowed 
 to thicken to an injurious extent, would last as long, or nearly as 
 long, as land boilers. It is found, however, that the boilers in 
 which these expedients are adopted with the greatest effect and 
 regularity are, nevertheless, less durable in a very large propor- 
 tion than land boilers. Thus, while a land boiler will last for 
 twenty years, a marine boiler, similarly constructed, will, even 
 with the greatest care, be worn out in four or five years. 
 
 The cause of this rapid destruction of the boiler is corrosion, 
 but how this corrosion is produced is a question which has not 
 hitherto been satisfactorily answered. It is contended that this 
 is not to be ascribed to any chemical action of the sea water on 
 the iron, inasmuch as the flues of marine boilers rarely show any 
 deterioration from this cause, and even in worn-out marine boilers 
 the hammer-marks on the flues are as conspicuous as when they are 
 fresh from the boiler-maker. The thin film of scale which covers 
 the interior surface would rather protect the iron from the action 
 of the water. In fine, the seat of the corrosion is almost never 
 those parts of the boiler which are in contact with the water. It 
 is that part of the metal which includes the steam space that 
 exhibits corrosion ; but even there the effect is so irregular, that 
 no data can be obtained by which the cause can be satisfactorily 
 traced. The part which is most rapidly corroded in one boiler is 
 not at all affected in another ; and in some cases we find one side 
 of the steam- chest attacked, the other side being untouched. 
 Sometimes the iron exfoliates in flakes, while in others it appears 
 as though it were eaten away by an acid. 
 
 43. In the application of the steam-engine to the propulsion of 
 vessels in voyages of great extent, the economy of fuel acquires 
 an importance greater than that which appertains to it in land 
 engines, even in localities the most removed from coal-mines, and 
 where its expense is greatest. The practical limit to steam 
 voyages being determined by the greatest quantity of coals which 
 a steam vessel can carry, every expedient by which the efficiency 
 of the fuel can be increased becomes a means, not merely of a 
 saving of expense, but of an increased extension of steam-power to 
 navigation. Much attention has been bestowed on the augmenta- 
 tion of the duty of engines in the mining districts of Cornwall, 
 where the question of their efficiency is merely a question of 
 economy ; but far greater care should be given to this subject, 
 when the practicability of maintaining intercourse by steam 
 
 143 
 
STEAM NAVIGATION. 
 
 between distant points of the globe, will perhaps depend on the 
 effect produced by a given quantity of fuel. So long as steam 
 navigation was confined to river and channel transport and to 
 coasting voyages, the speed of the vessel was a paramount con- 
 sideration, at whatever expenditure of fuel it might be obtained ; 
 but since steam navigation has been extended to ocean voyages, 
 where coals must be transported sufficient to keep the engine in 
 operation for a long period of time without a fresh relay, greater 
 attention has been bestowed upon the means of economising it. 
 
 Much of the efficiency of fuel must depend on the management 
 of the fires, and therefore on the skill and care of the stokers. 
 Formerly the efficiency of firemen was determined by the abundant 
 production of steam ; and so long as the steam was evolved in 
 superabundance, however it might have blown off to waste, the duty 
 of the stoker was considered as well performed. The regulation of 
 the fires according to the demands of the engine was not thought 
 of, and whether much or little steam was wanted, the duty of the 
 stoker was to urge the fires to their extreme limit. 
 
 Since the resistance opposed by the action of the paddle-wheels 
 of a steam-vessel varies with the state of the weather, the con- 
 sumption of steam in the cylinders must undergo a corresponding 
 variation ; and if the production of steam in the boilers be not 
 proportioned to this, the engines will either work with less effi.- 
 ciency than they might do under the actual circumstances of the 
 weather, or more steam will be produced in the boilers than the 
 cylinders can consume, and the surplus will be discharged to waste 
 through the safety valves. The stokers of a marine engine, there- 
 fore, to perform their duty with efficiency, and obtain from the fuel 
 the greatest possible effect, must discharge the functions of a self- 
 regulating furnace, such as has been already described : they must 
 regulate the force of the fires by the amount of steam which the 
 cylinders are capable of consuming, and they must take care that no 
 nnconsumed fuel is allowed to be carried away from the ash-pit. 
 
 44. Formerly the heat radiated from every part of the surface 
 of the boiler was allowed to go to waste, and to produce injurious 
 effects on those parts of the vessel to which it was transmitted. 
 This evil, however, has been removed by coating the boilers, 
 steam-pipes, &c. , of steam- vessels with felt, by which the escape 
 of heat from the surface of the boiler is very nearly, if not alto- 
 gether, prevented. This felt is attached to the boiler surface by 
 a thick covering of white and red lead. This expedient was first 
 applied in the year 1818 to a private steam vessel of Mr. Watt's, 
 called the Caledonia ; and it was subsequently adopted in another 
 vessel, the machinery of which was constructed at Soho, called 
 the James Watt. 
 
Fig. 10. 
 
 STEAM NAVIGATION. 
 
 CHAPTEE III. 
 
 45. Economy of fuel.— 46. Widtli and depth of furnace.— 47. Advantage 
 of expansive action.— 48. Siamese engines. — 49. Simplified arrange- 
 ments. — 50. Number and position of cylinders. — 51. Proportion of 
 diameter to stroke. — 52. Oscillating engines. — 53. Engines of the 
 Peterhofr. — 54. Propellers.— 55. The common paddle-wheels. — 56. 
 Feathering paddles.— 57. Morgan's paddle-wheel.— 58. Field's split 
 paddles.— 59. American paddle-wheel.— 60. Practical objections to 
 feathering paddles. — 61. Proportion of marine engines. — 62. Sub- 
 merged propellers.— 63. Their disadvantages.— 64. Screw-propellers. 
 —65. Pitch and slip, — 66. Manner of mounting screw-propellers. — 
 67. Their various forms. 
 
 45. The economy of fuel depends in a great degree on the 
 arrangement of the furnaces, and the method of feeding them. 
 In general, each boiler is worked by two or more furnaces 
 communicating with the same system of flues. While the furnace 
 Lardker's Museum op Science, l 145 
 
 No. 126. 
 
STEAM NAVIGATION. 
 
 is fed, tlie door being open, a stream of cold air rushes in, passing 
 over the burning fuel and lowering the temperature of the flues : 
 this is an evil to be avoided. But, on the other hand, if the fur- 
 naces be fed at distant intervals, each furnace will be unduly 
 heaped with fuel, a great quantity of smoke will be evolved, 
 and the combustion of the fuel will be proportionally imperfect. 
 The process of coking in front of the grate, which would insure a 
 complete combustion of the fuel, has been already described in our 
 tract on the Steam Engine. A frequent supply of coals, however, 
 laid carefully on the front part of the grate, and gradually pushed 
 backwards as each fresh feed is introduced, would require the fire 
 door to be frequently opened, and cold air to be admitted. It 
 would also require greater vigilance on the part of the stokers, 
 than can generally be obtained in the circumstances in which they 
 work. In steam-vessels the furnaces are therefore fed less fre- 
 quently, fuel is introduced in greater quantities, and a less perfect 
 combustion produced. 
 
 When several furnaces are constructed under the same boiler, 
 communicating with the same system of flues, the process of feed- 
 ing, and consequently opening one of them, obstructs the due 
 operation of the others, for the current of cold air which is thus 
 admitted into the flues checks the draught, and diminishes the 
 efiiciency of the furnaces in operation. It was formerly the practice 
 in vessels exceeding one hundred horse-power, to place four 
 furnaces under each boiler, communicating with the same system 
 of flues. Such an arrangement was found to be attended with a 
 bad draught in the furnaces, and therefore to require a greater 
 quantity of heating surface to produce the necessary evaporation. 
 This entailed upon the machinery the occupation of more space in 
 the vessel in proportion to its power ; it has therefore been more 
 recently the practice to give a separate system of flues to each 
 pair of furnaces, or, at most, to every three furnaces. When three 
 furnaces communicate with a common flue, two will always be in 
 operation, while the third is being cleared out ; but if the same 
 quantity of fire were divided among two furnaces, then the clearing 
 out of one would throw out of operation half the entire quantity 
 of fire, and during the process the evaporation would be injuriously 
 diminished. 
 
 46. It is found by experience, that the side plates of furnaces are 
 liable to more rapid destruction than their roofs, owing, probably, 
 to a greater liability to deposit. Furnaces, therefore, should not 
 be made narrower than a certain limit. Great depth from front to 
 back is also attended with practical inconvenience, as it renders 
 firing tools of considerable length, and a corresponding extent of 
 stoking room necessary. It is recommended by those who have had 
 146 
 
EXPANSIVE ACTION. 
 
 mucn practical experience in steam-vessels, that furnaces six feet 
 in depth from front to back should not be less than three feet 
 in width to afford means of firing with as little injury to the sida 
 plates as possible, and of keeping the fires in the condition 
 necessary for the production of the greatest effect. The tops of 
 the furnaces scarcely ever decay, and are seldom subject to an 
 alteration of figure, unless the level of the water be allowed to 
 fall below them. 
 
 47. The method by which the greatest quantity of practical 
 'effect can be obtained from a given quantity of fuel must, how- 
 ever, mainly depend on the extended application of the expansive 
 principle. This has been the means by which an extraordinary 
 amount of duty has been obtained from the Cornish engines. The 
 difficulty of the application of this principle in marine engines, has 
 arisen from the objections entertained in Europe to the use of 
 steam of high-pressure, under the circumstances in which the 
 engine must be worked at sea. To apply the expansive principle, 
 it is necessary that the moving power at the commencement of the 
 stroke shall considerably exceed the resistance, its force being 
 gradually attenuated till the completion of the stroke, when it 
 will at length become less than the resistance. This condition 
 may, however, be attained with steam of limited pressure, if 
 the engine be constructed with a sufficient quantity of piston 
 surface. 
 
 48. This method of rendering the expansive principle available at sea, 
 and compatible with low-pressure steam, was projected and executed by 
 Messrs. Maudslay and Field. Their improvement consists in adapting 
 two steam cylinders in one engine, in such a manner that the steam shall 
 act simultaneously on both pistons, causing them to ascend and descend 
 together. The piston-rods are both attached to the same horizontal cross- 
 head, whereby their combined action is applied to one crank by means of a 
 connecting-rod placed between the pistons. 
 
 • A section of such an engine (which has been called the Siamese engine), 
 made by a plane passing through the two piston-rods p and cylinders, is 
 represented in fig. 9. The piston-rods are attached to a cross-head c, 
 which ascends and descends with them. This cross-head drives upwards 
 and downwards an axle d, to which the lower end of the connecting-rod 
 E is attached. The other end of the connecting-rod drives the crank- 
 pin F, and imparts revolution to the paddle-shaft g. A rod h conveys 
 motion by means of a beam i to the rod k of the air-pump l. 
 
 Engines constructed on this principle were applied in several steamers, 
 and amongst others in her Majesty's steam-frigate *'Eetribution." 
 
 49. Within the last ten or fifteen years, and especially 
 since the more general adoption of the screw-propeller, the 
 marine engine has been greatly simplified in its mechanical 
 arrangements. Its bulk has thus been diminished, as well as 
 
 L 2 147 
 
STEAM NAYIGATIOIT. 
 
 the cost of construction ; and the profitable tonnage of the 
 vessel has been increased in a corresponding proportion. The 
 beam and its appendages have been very generally laid aside, 
 and the piston-rods have been more directly connected with 
 the cranks. 
 
 In some cases the piston-rods are kept in their direction by 
 guides, and their rectilinear motion is accommodated to the 
 
 Fig. 9. 
 
 rotation of the cranks by connecting-rods, which .consequently 
 have an oscillation between the extreme points of the play of the 
 cranks. 
 
 In other cases the cylinders themselves receive this oscillation. 
 In such cases the connecting-rods are dispensed with, and the 
 ends of the piston-rods are immediately jointed to the cranks. 
 The oscillation of the piston causes the motion of the valves neces- 
 sary for the alternate admission and escape of the steam on the 
 one and the other side of the piston. 
 
 50. The number of cylinders varies, being generally two, but 
 148 
 
OSCILLATING ENGINES. 
 
 Bometimes three, sometimes four, and sometimes, tliougli very 
 exceptionally, only one. 
 
 The position of the cylinders is subject to great variation. 
 They are placed with their axes sometimes vertical, sometimes 
 horizontal, and sometimes oblique. 
 
 51. The proportion of the diameter to the stroke is subject to 
 like variation. The general tendency has been to increase the 
 relative magnitude of the diameter, which in recently built 
 engines is sometimes more than twice the stroke, and rarely less 
 than two-thirds of it. Thus in the engines of the " Niger," con- 
 structed by Messrs. Maudslay and Field, the cylinders have 48 
 inches diameter, with only 22 inches stroke ; and in the " Simoom," 
 by Boulton and Watt, they have 44 inches diameter, with 30 
 inches stroke. 
 
 The object of shortening the stroke is to diminish the momentum 
 of the piston, of which the motion requires to be so frequently 
 reversed. 
 
 52. In engines constructed on the oscillating principle, the top 
 of the piston-rod is coupled with the crank, and the piston-rod 
 moves backward and forward in the direction of the axis of the 
 cylinder, while its extremity revolves in a circle with the crank. 
 It is therefore necessary that the cylinder should oscillate from 
 side to side, to accommodate the motion of the piston-rod to that 
 of the crank. For this purpose the cylinder is provided on each 
 side with a short hollow pivot or trunnion, on which it swings ; 
 and through one of these trunnions the steam enters the cylinder 
 from the boiler, while it escapes through the other to the condenser. 
 The alternate admission and escape of steam on the one side and 
 the other of the piston, is regulated by a valve attached to the 
 cylinder and swinging with it. In the larger class of engines, 
 however, two valves are usually employed for this purpose, and 
 are so arranged as to balance one another. 
 
 Oscillating engines are usually placed immediately under the 
 cranks, and occupy no greater length in the vessel than the 
 diameter of the cylinder. On the shaft which connects the 
 engine, called the intermediate shaft, a crank is forged which 
 in its revolutions gives motion to the piston of the air-pump. 
 
 53. The arrangements generally employed at present in the most 
 improved vessels propelled by oscillating engines, will be understood by 
 reference to fig. 10, which represents the transverse section of the steam- 
 yacht "Peterhoff, " constructed for the Emperor of Russia, by Messrs. Rennie, 
 and fig. 11, which is a side view of the engines of the same vessel. These 
 figures are copied with the permission of the publishers and the authors, 
 from, the article on the steam-engine, in the last edition of Erande's 
 "Dictionary of Science." A, A are the cylinders ; b, b are the piston-rods, 
 which are connected immediately with the cranks c, c ; d is a crank on 
 
 149 
 
STEAM NAVIGATION. 
 
 the iatermediate shaft for -working the piston of the air-pump e ; p, p are' 
 
 s^^^^^l M" ingto the steam-trunnions 
 
 the slide-valves, by which 
 the admission of the steam 
 to the cylinders is regu- 
 lated ; G, G are double 
 eccentrics on the inter- 
 mediate shaft, whereby 
 the valves f, f are moved ; 
 H is a handle, whereby the 
 engines may be stopped, 
 started, or reversed ; i, i 
 are the steam-pipes lead- 
 
 K, K, on which, and on 
 other trunnions, connected 
 with the pipe M, the cylin- 
 
 ders oscillate ; n, n are 
 
 pumps, the pistons ot 
 which are attached to the 
 
 = trunnions, and are worked 
 
 water pipe, through tvhich 
 the water which has accomplished the function of condensing the steam is 
 ejected over-board. The same letters refer to the same parts in the two figures. 
 
 54. To obtain from the moving power its full amount of meclia- 
 nical effect in propelling the vessel, it would be necessary that it 
 should constantly act against the water in a horizontal direction,, 
 and with a motion contrary to the course of the vessel. No system 
 of propellers has, however, yet been contrived capable of perfectly 
 accomplishing this. Patents have been granted for many 
 ingenious mechanical combinations to impart to the propelling 
 surfaces such angles as appeared to the respective contrivers most 
 advantageous. In most of these the mechanical complexity has 
 formed a fatal objection. No part of the machinery of a steam- 
 vessel is so liable to become deranged r t sea as the propellers ; 
 and, therefore, that simplicity of constru?tion which is compatible 
 with those repairs which are possible on such emergencies is quite 
 essential for safe practical use. 
 
 55. The ordinary paddle-wheel, as has been aheady stated, is a wheel 
 revolving upon a shaft driven by the engine, and carrying upon its cir- 
 cumference a number of flat boards, called paddle-boards, which are 
 secured by nuts and braces in a fixed position ; and that position is such 
 that the planes of the paddle-boards diverge from the centre of the shaft 
 on which the wheel turns. The consequence of this arrangement is that each 
 paddle-board can only act in that direction which is most advantageous for 
 the propulfcion of the vessel when it arrives at the lowest point of the wheel. 
 In fig. 12, let 0 be the shaft on which the common paddle-wheel revolves ; 
 the positions of the paddle-boards are represented at a, b, c, &c. ; x Y 
 represents the water-line, the course of the vessel being supposed to be 
 from X to Y ; the arrows represent the direction in which the paddle-wheel 
 
 150 
 
COMMON PADDLE-WHEEL. 
 
 reyolves. The wheel is immersed to the depth of the lowest paddle-board, 
 since a less degree of immersion would render a portion of the surface of 
 each paddle-board mechanically useless. In the position a, the whole 
 force of the paddle-board is efficient for propelling the vessel ; but as the 
 paddle enters the water in the position h, its action upon the water not 
 being horizontal, is only partially effective for propulsion : a part of the 
 force which drives the paddle is expended in depressing the water, and the 
 remainder in driving it contrary to the course of the vessel, and, therefore, 
 
 by its re-action producing a certain propelling effect. The tendency, how- 
 ever, of the paddle entering the water at h is to form a hollow or trough, 
 which the water, by its ordinary property, has a continual tendency to fill 
 up. After passing the lowest point A, as the paddle approaches the posi- 
 tion B, where it emerges from the water, its action again becomes oblique, 
 a part only having a propelling effect, and the remainder having a tendency 
 to raise the v/ater, and throw up a wave and spray behind the paddle- 
 wheel. It is evident that the more deeply the paddle-wheel becomes 
 immersed, the greater will be the proportion of the propelling power thus 
 wasted in elevating and depressing the water ; and if the wheel were 
 immersed to its axis, the whole force of the paddle-boards, on entering and 
 leaving the water, would be lost, no part of it having a tendency to propel. 
 If a still deeper immersion take place, the paddle-boards above the axis 
 would have a tendency to retard the course of the vessel. When the vessel 
 is, therefore, in proper trim, the immersion should not exceed nor fall 
 short of the depth of the lowest paddle ; but for various reasons it is 
 impossible in practice to maintain this fixed immersion : the agitation of the 
 surface of the sea causing the vessel to roll, will necessarily produce a great 
 variation in the immersion of the paddle-wheels, one becoming frequently 
 immersed to its axle, while the other is raised altogether out of the water. 
 Also the draught of water of the vessel is liable to change, by the variation 
 in the cargo ; this will necessarily happen in steamers which take long 
 voyages. At starting they are heavily laden with fuel, which as they 
 proceed is gradually consumed, whereby the vessel is lightened. 
 
 Fig. 12. 
 
 A 
 
 151 
 
STEAM NAVIGATION. 
 
 56. To remove this defect, and economise as mucli as possible the 
 propelling efiect of the paddle-boards, it would be necessary so to 
 construct them that they may enter and leave the water edgeways, 
 
 Fig. 13. 
 
 or as nearly so as possible ; such an arrangement would be, in 
 effect, equivalent to the process called feathering, as applied to 
 oars. Any mechanism which Avould perfectly accomplish this 
 would cause the paddles to work in almost perfect silence, and 
 would very nearly remove the inconvenient and injurious vibration 
 which is produced by the action of the common paddles. But the 
 construction of feathering paddles is attended with great difficulty, 
 under the peculiar circumstances in which such wheels work. 
 Any mechanism so complex that it could not be easily repaired 
 when deranged, with such engineering implements and skill as 
 can be obtained at sea, would be attended with great objections. 
 
 Feathering paddle-boards must necessarily have a motion inde- 
 pendently of the motion of the wheel, since any fixed position which 
 could be given to them, though it might be most favourable to 
 their action in one position, would not be so in their whole course 
 through the water. Thus the paddle-board when at the lowest- 
 point should be in a vertical position, or so placed that its plane, 
 if continued upwards, would pass through the axis of the wheel. 
 In other positions, however, as it passes through the water, it 
 should present its upper edge, not towards the axle of the wheel, 
 but towards a point above the highest point of the wheel. The 
 precise point to which the edge of the paddle-board should be di- 
 rected is capable of mathematical determination. But it will vary 
 according to circumstances, which depend on the motion of the 
 vessel. The progressive motion of the vessel, independently of 
 the wind or current, must obviously be slower than the motion of 
 the paddle-boards round the axle of the wheel ; since it is by the 
 difference of these velocities that the re- action of the water is pro- 
 duced, by which the vessel is propelled. The proportion, however, 
 between the progressive speed of the vessel and the rotative speed 
 of the paddle-boards is not fixed ; it will vary with the shape and 
 152 
 
FEATHERINa PADDLES. 
 
 structure of tlie vessel, and with its depth of immersion ; never- 
 theless it is upon this proportion that the manner in which the 
 paddle-hoards should shift their position must be determined. If 
 the progressive speed of the vessel were nearly equal to the rotative 
 speed of the paddle-hoards, the latter should so shift their position 
 that their upper edges should be presented to a point very little 
 above the highest point of the wheel. This is a state of things 
 which could only take place in the case of a steamer of a small 
 draught of water, shallop-shaped, and so constructed as to suffer 
 little resistance from the fluid. On the other hand, the greater 
 the depth of immersion, and the less fine the lines of the vessel, 
 the greater will be the resistance in passing through the water, 
 and the greater will be the proportion which the rotative speed of 
 the paddle-boards will bear to the progressive speed of the vessel. 
 In this latter case the independent niotion of the paddle-boards 
 should be such that their edges, while in the water, shall be pre- 
 sented towards a point considerably above the highest point of the 
 paddle-wheel. 
 
 A vast number of ingenious mechanical contrivances have been 
 invented and patented, for accomplishing the objects just explained. 
 Some of these have failed from the circumstance of their inventors 
 not clearly understanding what precise motion it was necessary to 
 impart to the paddle-boards ; others have failed from the com- 
 plexity of the mechanism by which the desired effect was produced. 
 
 57. One of these contrivances of late construction is represented in 
 fig. 11, being the paddle-wheel of the Eussian steamer "Peterhoff"." 
 To convey a general idea of the feathering principle, however, we 
 have represented in fig. 14 the form of wheel known as Morgan's 
 paddle-wheel. 
 
 TMs contrivance may be shortly stated to consist in causing the wheel 
 "wiich bears the paddles to revolve on one centre, and the radial arms 
 which move the paddles to revolve on another centre. Let abcdepgh 
 I K L he the polygonal circumference of the paddle- Vi^heel, formed of 
 straight bars, securely connected together at the extremities of the spokes 
 or radii of the wheel which turns on the shaft which is worked by the 
 engine ; the centre of this wheel being at o. So far this wheel is similar 
 to the common paddle-wheel; but the paddle-boards are not, as in the 
 common wheel, fixed at A B c, &c., so as to be always directed to the 
 centre o, but are so placed that they are capable of turning on axles which 
 are always horizontal, so that they can take any angle with respect to the 
 water which may be given to them. From the centres, or the line joining 
 the pivots on which these paddle-boards turn, there proceed short arms k, 
 firmly fixed to the paddle-boards at an angle of about 120°. On a motion 
 given to this arm k, it will therefore give a corresponding angular motion 
 to the paddle-board, so as to make it turn on its pivots. At the extremi- 
 ties of the several arms marked K is a pin or pivot, to which the 
 extremities of the radial arms l are severally attached, so that the angle 
 between each radial arm l and the short paddle arm k is capable of being 
 
 153 
 
STEAM NAVIGATION. 
 
 changed by any motion imparted to l ; the radial arms are connected at 
 the other end with a centre, round which they are capable of revolving. 
 Now, since the points A B c, &c., which are the pivots on which the paddle- 
 boards turn, are moved in the circumference of a circle, of which the centre 
 is o, they are always at the same distance from that point, consequently they 
 will continually vary their distance from the other centre P. Thus, when 
 a paddle-board arrives at that point of its revolution at which the centre 
 
 Fig. 14. 
 
 round which it revolves lies precisely between it and the centre o, its 
 distance from the former centre is less than in any other position. As it 
 departs from that point, its distance from that centre gradually increases 
 until it arrives at the opposite point of its revolution, where the centre o 
 is exactly between it and the former centre ; then the distance of the 
 paddle-board from the former centre is greatest. This constant change of 
 distance between each paddle-board and the centre p is accommodated by 
 the variation of the angle between the radial arm l and the short paddle- 
 board arm K : as the paddle -board approaches the centre p, this gradually 
 diminishes ; and as the distance of the paddle-board increases, the angle is 
 likewise augmented. This change in the magnitude of the angle, which 
 thus accommodates the varying position of the paddle-board with respect 
 to the centre p, v.'ill be observed in the figure. The paddle-board d is 
 nearest to p ; and it will be observed that the angle contained between l 
 and K is there very acute ; at E the angle between l and k increases, 
 154 
 
SPLIT PADDLES. 
 
 but is still acute ; at G it increases to a riglit angle ; at h it becomes 
 obtuse ; and at k, where it is most distant from the centre p, it becomes 
 most obtuse. It again diminishes at l, and becomes a right angle between. 
 A and B. Now this continual shifting of the direction of the short arm K 
 is necessarily accompanied by an equivalent change of position in the 
 paddle-board to which it is attached ; and the position of the second centre 
 p is, or may be, so adjusted that this paddle-board, as it enters the water 
 and emerges from it, shall be such as shall be most advantageous for pro- 
 pelling the vessel, and therefore attended with less of that vibration which 
 arises chiefly from the alternate depression and elevation of the water, 
 owing to the oblique action of the paddle-boards. 
 
 58. Field's split paddles. — In the year 1833, Mr. Field, of the firm of 
 Maudslay and Field, constructed a paddle-wheel with fixed paddle-boards, 
 but each board being divided into several narrow slips arranged one a little 
 behind the other, as represented in fig. 15. These divided boards he pro- 
 Fig. 15. 
 
 posed to arrange in such cycloidal curves that they must all enter the 
 water at the same place in immediate succession, avoiding the shock pro- 
 duced by the entrance of the common board. These split paddle-boards 
 are as efficient in propelling when at the lowest point as the common 
 paddle- boards, and, when they emerge, the water escapes simultaneously 
 from each narrow board, and is not thrown up, as is the case with common 
 paddle-boards. 
 
 ^ The number of bars, or separate parts into which each paddle-board 'is 
 divided, has been very various. When first introduced, each board was 
 divided into six or seven parts : this was subsequently reduced ; and in 
 the wheels of this form constructed for the government vessels, the paddle- 
 boards consist only of two parts, coming as near to the common wheel 
 
 155 
 
 i 
 
STEAM NAVIGATION. 
 
 as is possible, withotit altogether abandoning the principle of the split 
 paddle. 
 
 59. The paddle-wheels generally used in American steam-boats are 
 formed, as if by the combination of two or more common paddle-wheels, 
 placed one outside the other, on the same axle, but so that the paddle- 
 boards of each may have an intermediate position between those of the 
 adjacent one, as represented in fig. 16. 
 
 The spokes, which are bolted to cast-iron flanges, are of wood. These 
 
 flanges, to which they are so 
 ^'^S' bolted, are keyed upon the 
 
 paddle-shaft. The outer ex- 
 tremities of the spokes are 
 attached to circular bands or 
 hoops of iron, surrounding 
 the wheel ; and the paddle - 
 boards, which are formed of 
 hard wood, are bolted to the 
 spokes. The wheels, thus 
 constructed, sometimes con- 
 sist of three, and not unfre- 
 quently four, independent cir- 
 cles of paddle-boards, placed 
 one beside the other, and so 
 adjusted in their position, 
 that the boards of no two 
 divisions shall correspond. 
 
 The great magnitude of the 
 paddle-wheels, and the cir- 
 cumstance of the navigation 
 being carried on, for the most 
 part, in smooth water, have 
 rendered unnecessary, in Ame- 
 rica, the adoption of any of 
 those expedients for neutralising the effects of the oblique action of the 
 paddles, which have been tried, but hithei'to with so little success, m Europe. * 
 
 60. The practical objections to the use of the feathering prin- 
 ciple in general, go far to balance the advantages attending them. 
 According to Mr. Bourne, whose skill and experience on this 
 subject entitle his opinion to the highest respect, all expedients 
 of this class are expensive, both to make and maintain. The 
 Tvear and friction in such a multitude of joints is very consider- 
 able ; and if any of the arms get adrift, or break, they will be 
 whirled round like a flail, and may perhaps cut through the 
 paddle-box, or even the vessel. If the injury be of such a nature 
 that the wheels cannot be turned round (and this has sometimes 
 happened), it will follow that the engines will be virtually dis- 
 abled until the obstruction can be cleared away; and if the 
 weather be very stormy, or i;he vessel be in a critical situation, 
 
 * For a notice of the inland steam navigation of the United States, see 
 ** Railway Economy," chap. xvi. Also "Museum of Science and Art," 
 vol. ii. p. 17. 
 156 
 
PROPORTIONS OP ENGINES. 
 
 she may be lost in consequence of lier temporary derangement. 
 Upon the whole, therefore, the application of feathering wheels to 
 vessels intended to perform long voyages through stormy seas, 
 appears to be of doubtful propriety. For channel trips, and in 
 situations where the wheels can be carefully examined at short 
 intervals, the risk is not so great; but in that case nearly the 
 same benefits will be attained by increasing the length of the 
 paddle-fioats, and giving the wheels less dip. There is no mate- 
 rial difference between the performance of a feathering wheel and 
 that of a radial wheel, if the two wheels be of the same diameter, 
 and if they have both a light dip with long narrow floats. And, 
 as in sea-going vessels, the wheels must necessarily be of con- 
 siderable diameter, and as there is nothing to prevent the other 
 circumstances conducive to efiiciency from being observed, it 
 follows that in ocean-vessels radial wheels would be about as 
 efficient as feathering wheels, but for the circumstance of a vari- 
 able immersion. It is not necessary, however, that there should 
 be much variation in the immersion if large vessels be employed, 
 or if coal is more frequently taken on board during the voyage ; 
 and as neither of these alternatives is attended with the risk 
 incident to the use of feathering wheels, they appear to be entitled 
 to that preference which ultimately they are likely to obtain. 
 
 61. In oscillating engines the piston-rod is usually made one- 
 ninth of the diameter of the cylinder, and the crank -pin is made 
 about one-seventh of the diameter of the cylinder. The diameter 
 of the paddle-shaft miist have reference not merely to the 
 diameter of the cylinder, but also to the length of the stroke of 
 tlie piston, or, what is the same thing, to the length of the crank. 
 If the square of the diameter of the cylinder in inches be multi- 
 plied by the length of the crank in inches, and the cube-root of 
 the product be extracted, then that root multiplied by -242 will 
 give the diameter proper for the shaft in inches at the smallest 
 part. The diameter of the trunnions is regulated by the diameter 
 of the steam and eduction pipes, and these are each usually about 
 one-fifth of the diameter of the cylinder ; but it is better to make 
 the steam trunnions a little less, and the eduction trunnions a 
 little more, than this proportion. The steam and eduction pipes, 
 where they enter their respective trunnions, are kept tight by a 
 packing of hemp, which is compressed by a suitable ring or 
 gland, tightened by screws. In land engines the air-pump and 
 condenser are each made about one-eighth of the capacity of the 
 cylinder, but in marine engines they are made somewhat larger. 
 
 62. Submerged propellers, whatever be their form, are exempt 
 from many of the disadvantages which are common to every 
 species of paddle-wheel. It will be evident that the eifect of 
 
 157 
 
STEAM NAVIGATION. 
 
 sncli a propeller will be nearly the same, whatever position may 
 be given to it in the water. However the ship may pitch or roll, 
 or however unequal the surface of the sea may be, such a pro- 
 peller will always produce the same backward current without 
 any variation of effect. 
 
 The circumstances which prevent the co-operation of the power 
 of steam with that of the sails in steam- vessels propelled by the 
 common paddle-wheels, will not operate with submerged pro- 
 pellers, inasmuch as their effect is altogether independent of the 
 •careening of the ship, 
 
 63. But though this defect is remedied, the submerged pro- 
 pellers in general are still subject to objections, to which even the 
 common paddle-wheel is not obnoxious. Being permanently 
 submerged and liable to accident, fracture, and derangement from 
 various causes, they are inaccessible, and cannot be repaired at 
 sea. But, besides this, when the object in view is to take fall 
 advantage of the power of the sails at times when it is expedient 
 to suspend the action of the machinery, the submerged propeller 
 becomes an obstruction, more or less considerable, to the progress 
 of the vessel. Various expedients have been contrived, and in 
 some instances practically applied, by which the propeller can be 
 lifted out of the water when it is not in operation, but hitherto 
 this has not been found practically convenient, at least for com- 
 mercial vessels, though sometimes adopted for vessels of war. 
 
 64. The screw-propeller is similar in form and mechanical prin- 
 ciple to the hydraulic machine known as the screw of Archimedes. 
 A cylinder placed at the bottom of the vessel, and in the direction 
 of the keel, is surrounded by a spiral blade similar, precisely, to 
 the thread of a common screw, but projecting from it instead of 
 being cut into its surface. If such a screw were turned in a 
 solid, it would move forward through a space equal to the distance 
 between two contiguous threads in each revolution ; but the water, 
 not being solid, yields more or less to the re-action of the screw, 
 and consequently the screw moves forward through a space in each 
 revolution less than the distance between two contiguous threads. 
 
 65. The distance between two contiguous threads is technically 
 called the pitch of the screw ; a term, however, which is some- 
 times also used to express the angle formed by the blade of the 
 screw with its axis, such angle supplying the means of calculating 
 the distance between such contiguous threads. We shall here, how- 
 ever, use the term pitch in the former sense. The difference between 
 the pitch of the screw and the space through which the screw actu- 
 ally progresses in the water in one revolution is called the slip. 
 
 In the first vessels to which screw-propellers were applied, the 
 screw consisted of a single spiral blade, which made one convo- 
 168 
 
SCEEW-PROPELLBRS. 
 
 lution only round the cylinder. This arrangement was subse- 
 quently modified, and two convolutions and a half of a double- 
 threaded screw were used instead of one complete convolution of a 
 single-threaded screw. This plan has been occasionally varied, a 
 smaller fraction of a convolution being sometimes used. 
 
 It is found in practice that the amount of the slip in general 
 varies from one-tenth to one-twentieth of the pitch ; that is to 
 say, the actual velocity of the screw through the water is from 
 one-tenth to one-twentieth less than it would be if the screw 
 worked through a solid, or as an ordinary screw in its nut. 
 
 66, The screw-propeller is usually fixed upon an axis parallel 
 to the keel of the vessel, and mounted in a space in the dead wood 
 between the stern-post and rudder-post. It is usually suspended 
 on a short shaft, carried by a metal frame, having a rack on each 
 side, in which endless screws work, by means of which the frame 
 supporting the propeller can be lifted out of the water, so that the 
 screw can be repaired if required or a new one introduced without 
 putting the vessel into dock. 
 
 To enable the water to react in a manner analogous to that in 
 which the nut reacts upon the common screw, the thread requires 
 to be much deeper than if the screw worked in metal or wood, 
 and the pressing surface to be proportionally larger. Accordingly 
 screw-propellers are always made with much smaller central bodies, 
 and a much deeper thread than the common screw. They are also 
 made as large as possible in diameter, extending generally from 
 the keel to a point nearly level with the surface of the water. Thus 
 the diameter of the screw is little less than the draft of the vessel. 
 
 67. To convey some idea of the forms of screw-propellers, we 
 have represented in the annexed figures the forms of some of the 
 propellers most generally adopted. 
 
 In fig. 17 is represented a perspective view of Smith's screw-propeller, 
 with two threads or blades, as finally adopted in her Majesty's steamer 
 
 Pig. 17. Fig. 18. Fig. 19. Fig. 20. 
 
 ** Rattier." This is the form of the screw now most generally adopted in the 
 
STEAM NAVIGATION. 
 
 Eiitish navy. An end view or an elevation looking against the end of tie 
 sLaft is shown in fig. 18. Smith's three-thread screw differs from this 
 only in having three arms instead of two. 
 
 Fig. 21. Fig. 23. 
 
 Strimman's propeller is shown by an end view in fig. 19, and a side 
 view in fig, 20. 
 
 Sunderland's propeller, as applied in the "Rattler," is shown in fig. 21, 
 consisting of two flat plates, set upon arms, fixed to an axis revolving 
 beneath the water in the stern. In the "Eattler," this propeller was placed 
 in the stern in the dead wood, instead of projecting out b«hind the rudder 
 as in the Sunderland arrangement. 
 
 In fig. 22 is represented Woodcroft's propeller, also applied in thft 
 " Eattler." This has four arms or blades, and the pitch of the screw at it3 
 leading edge is less than the pitch at its terminal edge. 
 
 In fig. 23 * is represented, as set in the stern of the vessel, the form 
 of Hodson's screw, from which excellent results are said to have been 
 obtained. This form of screw has been much used in France, Holland, 
 and other countries of the continent; and in some cases in which the com- 
 mon screw has been superseded by a screw of this description, an 
 improvement has been obtained in the speed amounting to about a knot 
 an hour. Such results will only ensue when the original screw has been 
 of inadequate dimension, so that the loss by slip has been large in amount, 
 and the more the slip is reduced, the less will become the advantage of 
 any deviation from Smith's form of screw with uniform pitch.f 
 
 * Figs. 17 to 23 have been taken with the permission of the author 
 from Mr. Bourne's work "on the Screw-propeller." 
 f Bourne " on the Screw-propeller," p. 136. 
 
 160 
 
Fig. 26. 
 
 STEAM NAVIGATION. 
 
 CHAPTEE IV. 
 
 68. Effect of tlie screw-propeller reaction on the vessel. — 69. Their best 
 practical proportion , — 7 0. Their varyin g pitch . — 71. Relative advantages 
 of screw and paddle-wheels. — 72. Their effects in long sea-voj'-ages. 
 — 73. Experiments with the "Eattler" and '' Alecto." — 74. These 
 experiments continxied. — 75, Admiralty experiments. — 76. Govern- 
 ment report. — 77. Application of the screw in the commercial marine. 
 — 78. Application of screw to mail-vessels. — 79. Geared and direct 
 action. — 80. Geared-engines. — 81. Fairbairn's internal gearing. — 82. 
 Subdivision of the power among several cylinders. — 83. Protection 
 "from shot. — 84. Regulation of slides. — 85. Relative speed of screw and 
 vessel. — 86. Engines of the "Great Britain." — 87. Engines of the 
 Arrogant" and "Encounter." — 88. Various forms of screw-engines. 
 — 89. Cross action of H. M.'s screw steam-packet "Plumper."— 
 90. Auxiliary steam-power. — 91. Effect of screw-vessels head to 
 wind. — 92. Nominal and real horse-power. — 93. Official tables of the 
 strength of the steam-navy. 
 
 68. The screw, whatever be its form or structure, in driving 
 tlie water sternwards, sustains a corresponding reaction which takes 
 effect upon the screw- shaft, and produces an 'equivalent pressure 
 on its bearing to its anterior extremity. The force of this forward 
 thrust of the screw-shaft, combined with its velocity of rotation, 
 produced, in the earlier screw- vessels, considerable inconvenience 
 3n consequence of the friction attending it, and several cases 
 liAiiDNER's Museum of Science. m 161 
 
 No. 128. 
 
STEAM NAVIGATION. 
 
 occurred where the end of the shaft being rendered white-hot was 
 actually welded to the steel plate against which it pressed, although 
 a stream of water was continually running over the surface in 
 contact. "Various expedients have since then been proposed for 
 remedying this inconvenience. One of these was to let the end of 
 the shaft enter a tight cylinder of oil in the manner of a piston, 
 so that it would press against a liquid instead of a solid. Another 
 was to place a large collar upon the shaft which should press 
 against a number of balls or small rollers like those of a swivel- 
 bridge. Neither of these plans, however, appears to have been 
 so successful as to get into general use, and one or other of the 
 following expedients is now generally adopted. The thrust of 
 the screw-shaft is received either upon a number of collars or a 
 series of discs placed at the end of the shaft and resting on a 
 cistern of oil which is usually cast upon the base plate or some 
 solid part of the engine, and its end is sufficiently strong to bear 
 the thrust of the screw. Interposed, however, between the end of 
 the cistern and that of the shaft are two, three, or more discs of 
 metal, generally two inches thick, and having diameters equal to 
 that of the shaft. A bolt passes through their centre to keep 
 them in line, but they are each free to revolve in the bolt, and 
 where the shaft passes out of the cistern a collar of leather is 
 applied to prevent the oil from escaping. It will be obvious from 
 such an arrangement that if the end of the shaft which it presses 
 upon the discs begins to heat from undue friction, it will revolve 
 with somewhat more difficulty, and will consequently carry the 
 first disc round with it. The rubbing surfaces are therefore no 
 longer at the end of the shaft, but at the first disc and the second 
 disc. In fact the rubbing surfaces, instead of being limited to a 
 single disc, are distributed over several. Those surfaces which 
 begin to heat, and consequently to stick, will cease to rub, whereby 
 they will speedily become cool again and their efficiency conse- 
 quently be restored. (See Mr. Bourne's article on the "Screw- 
 Propeller " in the Appendix to Brande's Dictionary of Science 
 and Art.") 
 
 69. According to the same authority the best practical propor- 
 tion and form of screw-propellers for mercantile vessels are as 
 follows. Those of three blades are on the whole preferable. The 
 diameter should be as large as possible. When the area of the 
 circle described by the extremity of the arms of the screw has one 
 square foot for every two-and-a-half square feet in the area of 
 the midship section immersed, a very efficient performance is 
 obtained. The pitch of the screw should be equal to its diameter, 
 or perhaps a little exceed it, and the length measured parallel to 
 its shaft should be about one-sixth of a convolution. Thus, foi? 
 162 
 
PROPORTIONS OF SCREWS, 
 
 example, in the case of a screw 12 feet in diameter, the pitch 
 would be from 12 to 14 feet, and the length about 2 feet. 
 
 70. Screws are generally made with one uniform pitch, and 
 their blades are set at right angles to the shaft. A gradual 
 increase of pitch towards the leading end of the screw is, how- 
 ever, recommended. Thus, the pitch of the centre should be 
 about 10 per cent, less than at the circumference, for the centre 
 should merely screw through the water, without producing any 
 reaction or propelling force. The efficient part being near the 
 circumference, it is also recommended that the blades, instead of 
 being precisely perpendicular to the shaft, should be inclined a 
 little sternwards, so as to produce a tendency in the water which 
 they drive backwards to converge to a point. It is assumed that 
 this convergent tendency may balance the divergent tendency due 
 to the centrifugal force attending the revolution : so that the two 
 forces being in equilibrium will cause the water to be projected 
 backwards from the screw in a cylindrical column. In the case 
 of the ordinary screw, with blades at right angles to the shaft, 
 the water projected backwards assumes the figure of the frustum 
 of a cone, and a certain proportion of the power is thereby lost. 
 
 71. The relative advantages of screw and paddle-propellers 
 depend in a great degree upon the immersion. It appeared from 
 experiments made on a considerable scale with steamers of the 
 Royal IS^avy, that in deep immersion the screw has an advantage 
 over the paddle-wheel of one-and-a-half per cent. ; but that, 
 with medium immersion, the paddle-wheel had an advantage of 
 one-and-three- quarters per cent, over the screw, an advantage 
 which was augmented to four-and-three-quarters per cent, for 
 light immersions. It appears, therefore, that the screw-propeller 
 has a certain advantage over the paddle when the vessel is deep 
 in the water, and that, on the other hand, the paddle gains an 
 advantage over the screw in proportion as the immersion is less. 
 
 72. In long sea voyages, where the immersion is liable to con- 
 siderable variation by reason of the lightening of the vessel owing 
 to the consumption of the fuel, the screw will have the advantage 
 over the paddle in the commencement of the voyage, and the paddle 
 over the screw towards the end of it. In rough weather, where, 
 by the rolling and pitching of the vessel, the paddle-wheels are 
 liable at one time to be deeply plunged in the water, and at another 
 to be raised out of it, the screw will have an obvious advantage. 
 
 73. In his work upon the screw-propeller, Mr. Bourne has 
 given the details of a series of important experiments made with 
 H. M. steamers ''Rattler" and "Alecto," to determine the 
 relative advantages of screw and paddle-wheels against a head 
 wind. The result of these experiments seemed to prove, that 
 
 M 2 163 
 
STEAM NAVIGATIOK. 
 
 under such conditions the screw is less efficient than the paddle ; 
 for though both vessels attained the same speed of four knots 
 against a strong head wind, yet, in the case of the " Alecto," this 
 performance was attained with a velocity of the engine of 12 
 strokes per minute, whereas in the Eattler " it was only attained 
 with a velocity of the engine of 22 strokes per minute. It follows, 
 therefore, that a screw-vessel in proceeding head to wind will 
 require 1-8 times, or nearly twice the quantity of fuel to do the 
 same amount of work. The screw, in fact, revolves at nearly the 
 same velocity whether the wind is adverse or favourable, or 
 whether the vessel is lying at anchor ; and this is a serious defect 
 in the case of vessels intended to encounter adverse winds. In the 
 case of vessels, however, which use the screw only as a resource in 
 calms, or as an auxiliary to the sails, this disadvantage will not be 
 experienced, since such vessels have no pretensions to the capability 
 of proceeding in direct opposition to a strong head wind. 
 
 74. Among the experiments made with the ''Alecto" and 
 ''Rattler," some of the most interesting and important were 
 directed to the determination of the relative towing powers of the 
 screw and paddle-wheel. For this purpose the two ships were 
 lashed stern to stern, and the engines of both were set to work so 
 as to make them draw the connecting chain in opposite directions. 
 In these and all other cases where screw and paddle- vessels of 
 equal power and size have been thus connected, the screw-vessel 
 has preponderated, and towed the paddle-vessel as soon as the 
 engines were set to work. 
 
 When the "Rattler" and "Alecto" were lashed together in this 
 manner, the " Alecto' s " engines were set on first, and she was 
 allowed to tow the " Rattler" at the rate of two knots an hour. 
 The " Rattler's " engines were then set on. In five minutes the 
 two vessels became completely stationary. The "Rattler" theil 
 began to move ahead, and towed the " Alecto " against the whole 
 force of her engines, at the rate of 2-8 knots per hour. In like 
 manner the " Niger" towed the " Basilisk " astern, in opposition 
 to the force of her engines at the rate of 1*1 knots per hour. The 
 natural inference from this experiment would be that the screw is 
 more suitable for towing than the paddle ; yet this inference is not 
 confirmed by the experiment, for when the " Niger " and 
 "Basilisk" were each set to tow the other alternately, in the 
 usual manner in which a steamer tows a ship, it was found that 
 the " Niger " towed the " Basilisk " at a speed of 5-63 knots, with 
 593-9 horse-power, and that the "Basilisk" towed the "Niger" 
 at the rate of 6 knots, with 572*3 horse-power. The paddle- 
 vessel, therefore, accomplished in towing the largest speed with 
 the least power. It has also been found that when a paddle 
 
ADMIRALTY EXPERIMENTS. 
 
 and screw-vessel set stern to stern push one another instead of 
 pulling one another, the paddle-vessel preponderates, whereas, if 
 they pull, the screw-vessel preponderates. These circumstances 
 seem to show that the power of a screw- vessel to tow. a paddle- 
 vessel astern, when the two are tied together, does not arise from 
 any superior tractive efficacy of the screw itself, hut is due to the 
 centrifugal action of the screw, which raises the level of the water 
 at the stern, so that the vessel gravitates down an inclined plane.* 
 
 75. The first experiments tried by the Admiralty with the 
 screw-propeller were made in 1840-41 ; and in the next three 
 years, 1842-44, eight screw vessels were built. This number was 
 augmented by twenty-six in 1845. In 1848 there were not less 
 than forty-five government screw-steamers afloat ; and since that 
 time, and more especially since the commencement of the war 
 with Russia, the increase of the scr^w-steam navy has gone on at 
 a rate which justifies the conclusion that ere long no vessel of 
 war, of whatever class, in the British navy wiU be unprovided 
 with the power, to a greater or less extent, of steam propulsion. 
 
 76. In a government official report of the results of various trials 
 of the performance of screw-steamers, dated so far back as May 
 1850, before that propeller had yet reached its present state of 
 perfection, it is stated as then highly probable that fine sailing 
 vessels, fitted with auxiliary screw-power, would be found abl^ 
 if not to rival, at least to approach, full-powered and expansively 
 acting steam-ships, in respect of their capability of making a long 
 voyage with certainty and in a reasonably short time. 
 
 " Another application of the screw, although inferior in general 
 importance to its application as a propeller to ordinary ships," 
 says the same report, "is certainly deserving of more attention 
 than is commonly paid to it, namely, as a manceuvrer to those 
 large ships in which engines of considerable power cannot be 
 placed, or in which it is considered unadvisable to place them. 
 Ko doubt can be entertained of the efficiency of such an instru- 
 ment worked by an engine of even fifty horse-power. The full 
 extent, however, of its utility cannot perhaps be thoroughly 
 appreciated until it shall have been extensively used in her 
 Majesty's navy." 
 
 Since the date of this report that experience which was wanted 
 has been obtained, and the extensive use of the screw has been 
 adopted, and the results fully confirm all those anticipations. 
 
 77. But it is not only in her Majesty's navy, but in the national 
 commercial marine, and not only as an auxiliary propeller, but as 
 an independent and most efficient agent of propulsion, that the 
 screw has been found to answer in practical navigation. In 1849, 
 
 * Bourne " on the Screw-propeller," Chap. IV. 
 
 165 
 
STEAM NAVIGATION. 
 
 before it had yet attained all its present degree of perfection, it 
 was in extensive operation under the direction of the General 
 Screw Shipping Company. Seven vessels belonging to that com- 
 pany were, in operation during the twelve months ending 31st 
 December, 1849, during which time they performed 170 voyages, 
 being an average of about 24| voyages per vessel, The total dis- 
 tance run was 110849 geographical miles, being at the average 
 rate of 15835 miles per vessel, and about 648 miles per voyage. The 
 average speed was 8 to geographical miles per hour, and only one 
 casualty, and that one in the Thames, occurred durin[^ the year. 
 
 The speed of the best and most recent of these vessels in still 
 water, running the measured mile in the long reach ot the Thames, 
 was found to be 9-68 knots per hour. 
 
 78. Practical authorities have suggested, that the greatly in- 
 creased and rapidly increasing number of screw ships running 
 between the British and American ports, suggests the expediency 
 of a revision of the post-office contracts, with a view to public 
 economy, without any real sacrifice of efficiency. It is considered 
 that no difference of time worthy of consideration now prevails 
 between the passages of the mail-packets and the screw- vessels ; 
 but even admitting a difference, it is certainly not so great as that 
 which exists between the speed of the mail and that of the 
 express trains on railways. If then the mail contracts on the 
 iron lines are sufficiently well performed by the trains of second- 
 rate speed, why may not the like contracts on the lines of water 
 be similarly executed, where the difference of cost would be 
 enormous, and the difference of speed comparatively insignificant. 
 
 It is obvious that these observations are applicable not only to 
 the lines of steamers which carry the United States and Canadian, 
 but also to the West Indian, and in a word, to all the ocean lines. 
 
 79. But when screw propulsion is used, a much greater velocity 
 of revolution is required to be given to the screw- shaft, — a much 
 greater number of revolutions per minute being necessary, than 
 the greatest number of strokes per minute made by any steam- 
 engine of the common construction. It was necessary, therefore, 
 in adopting screw propulsion, either to provide expedients by which, 
 the velocity of rotation of the screw-shaft shall be greater than 
 that of the crank-shaft, in the requisite proportion, or to modify 
 the form and proportions of the steam cylinders and their appen- 
 dages, so that the number of strokes per minute should be aug- 
 mented, so as to be equal to the necessary number of revolutions 
 per minute of the screw- shaft. 
 
 Both these contrivances have been adopted by different con- 
 structors. Engines constructed on the former plan are called geared 
 engines, and those constructed on the latter direct acting engines. 
 166 
 
GEAEED-ENGINES. 
 
 80. In geared engines the cranks are formed on one shaft, and tlie screw 
 ■fixed upon another, the directions of the two shafts being parallel. On the 
 crank-shaft is fixed a toothed-wheel, which 
 
 works in a smaller one, called a pinion, fixed ^^S- 24. 
 
 on the sci-ew-shaft. Thus in fig. 24, A inay .-(jiKEJt/i? 
 be regarded as the pinion fixed on the screw- ■ <]iJJ5f>'^,^|^^ 
 shaft, and b the wheel fixed on the crank- (Jl^^KIl/J^ 
 shaft, the teeth of the one being engaged in ^ic^Wlil^^ ^ 
 those of the other at c. 
 
 It is evident that the velocity of rotation ^ 
 of A will be greater than that of c in the tilWm 
 same proportion as that in which the number 
 
 of teeth in c is greater than the number of teeth in A. It is always possible, 
 •therefore, with a given speed of the crank-shaft, to impart a speed greater 
 in any required proportion to the screw-shaft by regulating in a cor- 
 responding manner the proportion of the teeth in those geared wheels. 
 
 81. One of the objections to the use of gearing in sea-going vessels is the 
 liability of the teeth to rapid wear, and to fracture from suddea shocks in 
 a rough sea. In order to diminish the risk of this by distributing the 
 pressure over a greater number of teeth, Mr. Fairbairn has adopted in 
 large screw-engines, constructed by him for the Royal Navy, a system of 
 'internal gearing in which the crank-shaft wheel has the teeth on its 
 internal periphery, the screw-shaft pinion revolving within it, as shown 
 in fig. 25. 
 
 In screw-vessels of war, all the macliinery should be placed 
 below the water-line, so as to be as effectually protected from 
 shot as the screw itself is. 
 
 82. When direct-acting engines without gearing are applied to . 
 screw-propelled vessels, the reciprocating motion of the piston 
 must be equal to the velocity 
 
 of the screw, that is, the ^s. 
 number of strokes per minute 
 of the piston must be equal 
 to the number of revolutions 
 per minute of the screw. Now 
 to render this compatible with 
 a sufficiently moderate recti- 
 linear motion of the piston, the 
 length of the stroke must bear 
 a very small proportion to the 
 diameter of the cylinder. This 
 has, in many cases, rendered 
 it necessary in such vessels to 
 subdivide the power of the 
 engines among four smaller cylinders, all the pistons being directly 
 attached to cranks on the screw-shaft instead of producing it by 
 two larger cylinders, in which an unmanageable proportion must 
 be adopted between the diameter and the stroke. 
 Another advantage derived from this subdivision of power is, that 
 
 167 
 
STEAM NAVIGATIOI^. 
 
 a number of small cylinders, ranged often in a horizontal position 
 on either side of the screw-shaft, allow of the play of all the 
 reciprocating parts within a small height, so as to keep tlie whole 
 below the water-line. 
 
 83. Another expedient for the protection of the machinery from 
 shot, is to place the coal-boxes on each side of it, and between it 
 and the timbers of the vessel, so that before a shot could reach it, 
 the fuel must be thoroughly penetrated. 
 
 84. The efficiency of a marine, like that of a land engine, depends 
 on the exact regulation of the slides by which the admission and 
 escape of the steam to and from the cylinder is governed. In all 
 cases the steam should be admitted at either end of the cylinder a 
 little before the arrival of the piston there, and at the same 
 moment the escape to the condenser should be stopped. By this 
 means the piston, on arriving at the end of the stroke, is received 
 by the steam just admitted mixed with a small portion of uncon- 
 densed s,team and air, whose escape to the condenser has been 
 interceptc d. These form a sort of air-cushion, against which the 
 stroke of the piston is broken, an effect which is called by the 
 practical men, not inappropriately; cushioning the piston. When 
 the steam is worked expansively, the slides must be capable of 
 such regulation as to shut it off at any required fraction of the 
 entire stroke, and when not so worked, it ought at all events to 
 be shut off before the stroke is quite completed, so as to relieve 
 the piston from its action a little before the termination of the 
 stroke. 
 
 It is easy to conceive that, to accomplish all these points, the 
 slides require the nicest imaginable adjustment ; and the openings 
 for the admission and escape of steam, the most exact regulation 
 both as to magnitude and position. 
 
 85. It will be evident on comparing the pitch of the ordinary 
 screw with the progressive rate at which the vessel moves through 
 the water, that, to produce the necessary speed, a much greater 
 velocity of rotation must be imparted to the screw, than is con- 
 sistent with the ordinary rate at which steam-engines work. It 
 has been already shown that this great velocity of rotation has 
 been obtained either by the interposition of gearing so adapted as 
 to augment the velocity, or by assimilating the engine in its form 
 and structure to a locomotive. 
 
 86. An example of a marine-engine, by which the necessary velocity is 
 imparted to the screw-shaft, by means of intermediate gearing, is pre- 
 sented in the case of the screw-engine constructed by Messrs. Penn and 
 Son, for the " Great Britain" steam-ship. The engines which are represented 
 in fig. 26, are constructed on the oscillating principle, and are almost 
 identical with the paddle-wheel engines, built by the same firm for 
 the "Sphinx." 
 
 168 
 
AEROGAHT AND ENCOUNTER. 
 
 The " Great Britain" is a vessel of 3500 measured tons ; her tonnage by 
 deplacement being 2970, and her draught 16 feet. The diameter of the 
 cylinder is 82^ inches ; the length of stroke, 6 feet ; the nominal power, 
 600 horses ; the diameter of the screw, 15^ feet ; its pitch, 19 feet, and 
 its length, 3 feet 2 inches. The screw has three arms or blades, and its 
 shaft is connected with the crank-shaft by a pair of toothed -wheels, which 
 have a multiplying power of 3 to 1, so that for every stroke of the piston, 
 the screw-shaft revolves three times. The ample proportion of 17-i- square 
 feet of heating surface per nominal horse-power, is provided in the boiler. 
 
 The crank-shaft, being put in motion by the engine, carries round the 
 great cog-wheel, or conjbination of cog-wheels, which are fixed upon it ; 
 and this wheel acting on smaller ones called pinions, on the screw-shaft, 
 impart to the latter the threefold velocity of revolution just mentioned. 
 
 87. As an example of screw-propelling engines working without gearing, 
 we give in fig. 27 those constructed by Messrs. Penn and Son for H. M.'s 
 screw- steamers "Arrogant" and "Encounter." In this case the cylinders 
 are horizontal, and are traversed through the centre by a pipe or trunk, upon 
 which the piston is cast. This trunk is projected through both ends of the 
 cylinder — the orifices through which it passes being rendered steam-tight 
 by proper packing. One end of the connectiDg-rod is attached to the 
 centre of the trunk, the other end being connected with the crank, which 
 is formed directly upon the screw-shaft. The air-pump lies in a horizontal 
 position, is double-acting, and placed within the condenser. A large pipe, 
 called the eduction pipe, leads from the cylinder to the condenser, where 
 the condensation is produced by a jet of cold water, and the warm water 
 resulting from the process is ejected by the air-pump through the waste- 
 pipe, and discharged overboard. In fig. 27 one cylinder and one air- 
 
 pump only are represented, but it must be understood that there are two, 
 precisely similar to each other, placed side by side. The valves by v/hich 
 the water is admitted to the air-pump from the condenser, and those by 
 which it passes from the air-pump to the hot well and waste-pipe, con- 
 sist of several discs of caoutchouc kept down by a central bolt, so as to 
 cover radial slits or orifices in a perforated plate. These valves are found 
 to operate without noise or shock, notwithstanding the high speed at which 
 the engine must work, in order to give the necessary velocity to the screw- 
 shaft withovit intervening gearing. The diameter of the cylinder of the 
 "Arrogant" and "Encounter" is 60 inches, and the diameter of the trunk 
 24 inches ; the latter being deducted from the former, leaves an eifectivc 
 
 Fig. 27. 
 
 169 
 
STEAM NAVIGATIOI^. 
 
 piston area equal to that of a piston 55 inches in diameter. In the * 'Arrogant" 
 the length of stroke is 3 feet, and in the "Encounter " it is 2 feet 3 inches. 
 The nominal power of both engines is 360 horses ; and the diameter of the 
 **Ari-ogant's" screw is 15 feet 6 inches, that of the "Encounter" being 12 feet. 
 The pitch of both is 15 feet, and the length 2 feet 6 inches. The "Arrogant" 
 is a vessel of 1872 tons burden, and the "Encounter" of 953 tons. The 
 whole machinery, including the boilers, is placed below the water liae, so 
 as to be protected from shot.* 
 
 88. Tiie forms of screw-propelling engines, whether they act on 
 the screw-shaft by intermediate gearing or directly, are infinitely 
 various. Drawings of not less than 15 different forms of geared- 
 engines, and the like number of direct acting engines, are given 
 in two large plates prefixed to Mr. Bourne's work on the screw-* 
 propeller, to which we must refer those who require information 
 of this detailed description. In the vessels of the Eoyal Marine 
 generally the cylinders are placed upon the sides, so that, by 
 diminishing the total height of the machinery above the floor 
 on which it rests, it may be kept below the water-line. In 
 commercial vessels a form of engines is frequently employed 
 resembling the land beam-engines, with the cylinder at one 
 end of the beam, and the connecting-rod at the other. In such 
 cases the connecting-rod extends downwards from the end of 
 the beam to the crank. In either case the cylinder is inverted, 
 and the connecting-rod proceeds from the end of the piston-rod 
 to turn the crank, the end of the piston-rod being of course 
 steadied by suitable guides. According to Mr. Bourne, the con- 
 struction of the engines described above in the case of the 
 "Arrogant" and " Encounter " is, on the whole, the best for screw- 
 vessels, but he thinks it might be preferable to put the trunk 
 into the air-pump instead of the cylinder. He considers also that 
 the condenser might be dispensed with, and the condensations 
 performed in the air-pump. In that case the flow of water to 
 and from the air-pump might be governed by a slide-valve, 
 similar to that which is employed to regulate the admission and 
 escape of steam to and from the cylinder. It seems probable that 
 slide-valves may be brought into general use for pumps of every 
 sort, but in the case of ordinary ones for raising water these valves 
 need not be like the common slide-valves, which in fact are not 
 well adapted to give sufficient area for such purposes, but may 
 consist of a short wide cylinder with gridiron oridces revolving 
 slowly at the top and bottom of the air air-pump. 
 
 89. The general arrangement of the machinery and fuel in screw- 
 propelled vessels of the Koyal Navy is illustrated by the transverse 
 section of H.M.'s screw steam-packet "Plumper," shown in fig. 28. 
 
 * Figs. 26 and 27 are copied, with the permission of the publisher and 
 the author, from Bi'ande's "Dictionary of Science and Art," to which the 
 170 
 
H. M. S. PLUMPER. 
 
STEAM NAVIGATIOJ^. 
 
 90. The question of auxiliary steam power to be used occa- 
 sionally, as well for commercial as for war purposes, is one of the 
 highest importance and interest, and one, moreover, which expe- 
 rience has not yet enabled us perfectly to understand and 
 elucidate. For commercial purposes the saving of fuel, when the 
 vessel has favourable winds, and the adaptation of her structure 
 to the conditions necessary for a sailing-vessel, is of the highest 
 importance ; and in naval warfare a propelling power, however 
 inadequate it may be for constant propulsion and the maintenance 
 of high speeds in long voyages, may nevertheless be all-sufficient 
 for conducting vessels into action or into hostile ports. 
 
 91. It has been already stated on the authority of Mr. Bourne, 
 and as the result of experiments made on a large scale, that 
 screw-vessels intended to go head to wind and work against 
 head-seas, are not as efficient with the same consumption of fuel 
 as paddle-wheel vessels. Under the combined operation of sails 
 and steam, however, they are generally as efficient, and, when 
 deeply laden, more so. A screw- vessel being divested of paddle- 
 boxes partakes more of the character of a sailing-ship ; neverthe- 
 less, from the experiments made with the " Niger" and Basilisk," 
 it does not appear that a screw-vessel is more efficient under sails 
 than a paddle-vessel, though such a result may naturally be 
 expected. The advantages, therefore, which attend the use of 
 screw-propelling engines as an auxiliary power, do not result from 
 any superiority of the screw as a propeller, nor from the increased 
 facility which it presents for the application of sails, but are to be 
 ascribed to the late employment in screw-vessels of wind-power 
 which costs nothing, instead of steam-power which costs much, 
 and also to the maintenance of lower rates of speed than are 
 thought necessary in paddle-wheel vessels. The screw is a less 
 cumbrous propeller than the paddle, and since it permits a much 
 higher speed of the engine, a greater engine power may be com- 
 pressed in a smaller compass. 
 
 On the whole, therefore, the screw for all the purposes of 
 auxiliary propulsion is much to be preferred ; nevertheless it must 
 be understood that its superior eligibility is not so much due to 
 its greater efficiency, as to the greater convenience in the applica- 
 tion of auxiliary steam-power which its employment affords. 
 
 92. The horse-power of marine engines is either nominal or real. 
 The nominal power is estimated by assuming a certain average 
 effective pressure of steam, and a certain average linear velocity 
 
 reader is referred for a great mass of important details, for wliich we 
 cannot here afford space. Still further information on the same subject 
 may be found in Mr. Bourne's work *'on the Screw-propeller" already 
 quoted, that gentleman being also the author of the article in Brande. 
 172 
 
TABLES OF STEAM NAVY. 
 
 of the piston. The pressure multiplied by the velocity gives the 
 effective force of the piston, or, what is the same, of the engine 
 exerted through a given number of feet per minute ; and since the 
 force called a horse-power means 33000 lbs. acting thus one foot 
 per minute, it follows that the nominal power of the engine will 
 be found by dividing the effective force exerted by the piston, 
 multiplied by the number of feet per minute through which it acts, 
 by 33000. 
 
 It is assumed in all Admiralty contracts, and generallj'- also in 
 those of the commercial marine, that, after deducting from the 
 total pressure of steam in the boiler that portion which is 
 neutralised by the gases and uncondensed steam in the condenser, 
 the friction of the moving parts and all other sources of resistance, 
 the actual available or effective pressure of steam upon the piston 
 is at the rate of 7 lbs. per square inch of piston surface. The 
 total nominal effective action of the piston in pounds will therefore 
 be found by multiplying the number of square inches in the area 
 of the piston by 7. 
 
 93. In the following tables, obtained from the government 
 authorities, will be found a complete statement of the strength of 
 her Majesty's steam navy up to the 1st of April, 1856. 
 
 By Table I. it appears that the number of line-of-battle ships 
 fitted and fitting with the screw-propeller was then 43, carrying 
 a total number of 3797 guns, and propelled by engines of the 
 collective power of 22950 horses. This is at the average rate of 
 88i guns, and 533 horses per vessel ; the proportion of guns to 
 horses being about 6 horses per gun. 
 
 By Table II. it appears that the number of frigates and 
 mortar-ships was 24, carrying collectively 889 guns, and propelled 
 by engines of 10560 horse-power, being at the average rate of 
 37 guns, and 440 horses per vessel ; the proportion of horses to 
 guns being about 12 horses per gun. 
 
 By Table III. it appears that there were 90 war steamers fitted 
 with paddle-wheels, carrying the total number of 500 guns, and 
 propelled by engines having the collective power of 24640 horses, 
 being at the average rate of 5^ guns, and 274 horses per vessel; the 
 proportion of horse-power to guns being about 50 horses per gun. 
 
 By Table lY. it appears that there were 76 smaller vessels fitted 
 with screw-propellers, consisting, of corvettes, sloops, and despatch 
 boats, carrying in all 761 guns, and propelled by engines of the 
 collective power of 16202 horses, being at the average rate of 10 
 guns and 213 horses per vessel; the proportion of horse-power to 
 guns being therefore about 21 hor&es per gun. 
 
 In Table V. is given the number and power of the troop and 
 store-ships, water-tanks, &c. ; in Table YI. a statement of the 
 
 173 
 
STEAM NAVIGATION. 
 
 steam-propelled gun-boats ; and in Table VII. a general summary 
 of the entire steam navy. 
 
 In Table VIII. is given a statement of tbe commercial steam 
 navy in March 1853. 
 
 TABLE I. 
 
 Line-of- Battle Ships fitted and fitting with the Screw-Propeller in Her 
 Majesty's Navy. 
 
 Name. 
 
 Agamemnon 
 Ajax . 
 Algiei-s . 
 Blenheim . 
 Brunswick 
 Csesar . 
 Centurion 
 Colossus 
 Conqueror 
 Cornwallis . 
 Cressy 
 Donegal 
 D. of Wellington 
 Edgar 
 
 Edinburgh . 
 
 1^ 
 
 600 
 450 
 450 
 450 
 400 
 400 
 40i' 
 400 
 800 
 200 
 400 
 800 
 700 
 600 
 450 
 
 1253 7500 
 
 Name. 
 
 Brought forward 
 Exmouth 
 Gil)raltar . 
 Hannibal 
 Hastings . 
 Hawke . 
 Hero . 
 Hogue . 
 Howe 
 Irresistible 
 James Watt 
 Majestic 
 Marlborough 
 Mars 
 Nile . 
 
 1253 
 90 
 
 100 
 90 
 60 
 60 
 90 
 60 
 
 120 
 80 
 91 
 80 
 
 130 
 
 n 
 
 7500 
 400 
 800 
 450 
 200 
 200 
 600 
 450 
 
 1000 
 400 
 600 
 400 
 800 
 400 
 500 
 
 2475 14700 
 
 Name. 
 
 Brought forward 
 Orion . . . 
 Pembroke . 
 Princess Eoyal . 
 Renown . . 
 Revenge . 
 Royal Albert . . 
 Royal George . 
 Royal Sovereign 
 Russell . . . 
 St. Jean d'Acre . 
 Sanspareil . 
 Victor Emanuel. 
 Victoria . . 
 Windsor Castle . 
 
 Total . . 
 
 2475 
 91 
 60 
 91 
 90 
 90 
 121 
 102 
 120 
 60 
 101 
 70 
 90 
 120 
 116 
 
 3797 
 
 14700 
 600 
 200 
 400 
 800 
 800 
 500 
 400 
 
 1000 
 200 
 600 
 350 
 600 
 
 1000 
 800 
 
 22950 
 
 TABLE n. 
 
 Frigates and Mortar-ships fitted and fitting with the Screw-Propeller 
 in Her Majesty's Navy. 
 
 
 Name. 
 
 03 
 
 a 
 
 1^ 
 
 
 Name. 
 
 to 
 
 a 
 
 ii 
 
 
 Name. 
 
 CO 
 
 a 
 
 rse 
 sver. 
 
 
 
 
 O o 
 
 
 
 6 
 
 
 
 
 
 
 
 
 
 
 
 
 WPh 
 
 
 
 
 
 1 
 
 Amphiou 
 
 34 
 
 300 
 
 
 Bt. forward 
 
 355 
 
 4140 
 
 
 Bt. forward 
 
 621 
 
 7350 
 
 2 
 
 Ariadne . . 
 
 30 
 
 350 
 
 10 
 
 Doris 
 
 32 
 
 800 
 
 18 
 
 Liffey . . . 
 
 50 
 
 600 
 
 3 
 
 Arrogant 
 
 46 
 
 360 
 
 11 
 
 Emerald . . 
 
 50 
 
 600 
 
 19 
 
 San Fiorenzo . 
 
 50 
 
 600 
 
 4 
 
 Aurora . 
 
 50 
 
 400 
 
 12 
 
 Eu rotas . 
 
 12 
 
 200 
 
 20 
 
 Sea-horse . . 
 
 12 
 
 200 
 
 5 
 
 Bacchante . . 
 
 50 
 
 600 
 
 13 Euryalus . . 
 
 51 
 
 400 
 
 21 
 
 Shannon 
 
 51 
 
 600 
 
 6 
 
 Chesapeake . 
 
 50 
 
 400 
 
 14 Forte . 
 
 60 
 
 400 
 
 22 
 
 Termagant 
 
 24 
 
 310 
 
 7 
 
 Cura^oa . . 
 
 30 
 
 350 
 
 15 Forth . . 
 
 12 
 
 200 
 
 23 
 
 Topaz 
 
 50 
 
 600 
 
 8 
 
 Dauntless 
 
 33 
 
 580 
 
 16 Horatio . . 
 
 8 
 
 250 
 
 24 
 
 Tribune . . 
 
 31 
 
 300 
 
 
 Diadem . . 
 
 32 
 
 800 
 
 17 
 
 Imp^rieuse . 
 
 51 
 
 360 
 
 
 
 
 
 9 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Total . . 
 
 889 
 
 10560 
 
 
 
 355 
 
 4140 
 
 
 
 621 
 
 7350 
 
 
 
 174 
 
TABLE III. — A List of War Steamers in Her Majesty's Service fitted witTt 
 Paddle-wheels. 
 
 
 Name. 
 
 Guns. 
 
 
 
 Name. 
 
 1 Guns. 1 
 
 Horse 
 Power. 
 
 
 Name. 
 
 Guns. 
 
 Horse 
 ^ Power. 
 
 1 
 
 Alecto . 
 
 5 
 
 200 
 
 
 Bt. forward 
 
 112 
 
 7560 
 
 
 Bt. forward 
 
 283 
 
 15869 
 
 2 
 
 Albany . . 
 
 4 
 
 100 
 
 32 
 
 Furious . 
 
 16 
 
 400 
 
 62 
 
 Penelope . . 
 
 16 
 
 650 
 
 '■A 
 
 Ardent . 
 
 
 200 
 
 33 
 
 Fury . , 
 
 
 515 
 
 63 
 
 Porcupine 
 
 3 
 
 132 
 
 4 
 
 Antelope . . 
 
 3 
 
 260 
 
 34 
 
 Geyser . 
 
 6 
 
 280 
 
 04 
 
 Prometheus . 
 
 5 
 
 200 
 
 5 
 
 Argus 
 
 6 
 
 300 
 
 35 
 
 Gorgon . . 
 
 6 
 
 320 
 
 65 
 
 Rhadamanthus 
 
 4 
 
 220 
 
 6 
 
 Asp . . . 
 
 
 50 
 
 36 
 
 Gladiator 
 
 6 
 
 430 
 
 66 
 
 Redpole . 
 
 1 
 
 160 
 
 ? 
 
 Avon 
 
 s 
 
 160 
 
 37 
 
 Harpy . 
 
 1 
 
 200 
 
 67 
 
 Retribution . 
 
 28 
 
 400 
 
 8 
 
 Bann . . . 
 
 
 80 
 
 38 
 
 Hecate 
 
 6 
 
 240 
 
 68 
 
 Rosamond 
 
 6 
 
 280 
 
 9 
 
 Banshee . 
 
 2 
 
 350 
 
 39 
 
 Hecla 
 
 6 
 
 240 
 
 69 
 
 Sampson . . 
 
 6 
 
 467 
 
 10 
 
 Barracouta 
 
 6 
 
 300 
 
 40 
 
 Hermes . . 
 
 6 
 
 220 
 
 70 
 
 Salamander . 
 
 6 
 
 220 
 
 11 
 
 Basilisk . 
 
 6 
 
 400 
 
 41 
 
 Hydra 
 
 6 
 
 220 
 
 71 
 
 Scourge . . 
 
 6 
 
 420 
 
 12 
 
 Black Eagle . 
 
 
 260 
 
 42 
 
 Inflexible 
 
 6 
 
 378 
 
 72 
 
 Shearwater 
 
 8 
 
 •160 
 
 13 
 
 Blood Hound . 
 
 3 
 
 150 
 
 43 
 
 Jackal 
 
 4 
 
 150 
 
 73 
 
 Sidon . 
 
 22 
 
 560 
 
 14 
 
 Brune 
 
 
 80 
 
 44 
 
 Kite 
 
 3 
 
 170 
 
 74 
 
 Spiteful . 
 
 6 
 
 280 
 
 15 
 
 Bull Dog . . 
 
 6 
 
 500 
 
 45 
 
 Leopard . . 
 
 18 
 
 560 
 
 75 
 
 Spitfire . . 
 
 
 140 
 
 16 
 
 Buzzard . 
 
 6 
 
 300 
 
 46 
 
 Lightning 
 
 3 
 
 100 
 
 76 
 
 Sphinx . 
 
 6 
 
 500 
 
 17 
 
 Caradoc , . 
 
 2 
 
 350 
 
 47 
 
 Lizard . . 
 
 1 
 
 150 
 
 77 
 
 Str emboli . . 
 
 6 
 
 280 
 
 18 
 
 Centaur . 
 
 6 
 
 540 
 
 4b 
 
 Locust . 
 
 3 
 
 100 
 
 78 
 
 Styx 
 
 6 
 
 280 
 
 19 
 
 Columbia . . 
 
 6 
 
 100 
 
 49 
 
 Lucifer . . 
 
 2 
 
 180 
 
 79 
 
 Tartarus 
 
 4 
 
 136 
 
 20 
 
 Comet , 
 
 
 80 
 
 50 
 
 Magicienne . 
 Medea 
 
 16 
 
 400 
 
 80 
 
 Terrible . 
 
 21 
 
 800 
 
 21 
 
 Cuckoo . . 
 
 3 
 
 100 
 
 51 
 
 6 
 
 350 
 
 81 
 
 Trident . . 
 
 6 
 
 350 
 
 22 
 
 Cyclops . 
 
 6 
 
 320 
 
 52 
 
 Medina . . 
 
 4 
 
 312 
 
 82 
 
 Triton 
 
 3 
 
 260 
 
 23 
 
 Dasher . . 
 
 2 
 
 100 
 
 53 
 
 Medusa . 
 
 4 
 
 312 
 
 83 
 
 Valorous . . 
 
 16 
 
 400 
 
 24 
 
 Dee . 
 
 4 
 
 200 
 
 54 
 
 Merlin . . 
 
 6 
 
 312 
 
 84 
 
 Vesuvius 
 
 6 
 
 280 
 
 25 
 
 Devastation . 
 
 6 
 
 400 
 
 55 
 
 Oberon . 
 
 3 
 
 260 
 
 85 
 
 Virago . . 
 
 
 300 
 
 26 
 
 Dragon . 
 
 6 
 
 560 
 
 56 
 
 Odin . 
 
 16 
 
 560 
 
 86 
 
 Vulture ■ . 
 
 6 
 
 470 
 
 27 
 
 Dover , . 
 
 
 90 
 
 57 
 
 Osborne . 
 
 2 
 
 430 
 
 87 
 
 Weser . 
 
 6 
 
 160 
 
 28 
 
 Driver . 
 
 'h 
 
 280 
 
 58 
 
 Otter . . . 
 
 3 
 
 120 
 
 88 
 
 Widgeon . 
 
 
 90 
 
 29 
 
 Firefly , . 
 
 4 
 
 220 
 
 59 
 
 Pigmy . 
 
 3 
 
 100 
 
 89 
 
 "Wildfire , . 
 
 
 76 
 
 30 
 
 Firebrand 
 
 6 
 
 410 
 
 60 
 
 Polyphemus . 
 
 5 
 
 200 
 
 90 
 
 Zephyr . 
 
 *3 
 
 100 
 
 3) 
 
 
 
 120 
 
 61 
 
 Pluto . 
 
 4 
 
 100 
 
 
 
 
 
 
 
 
 Total . . 
 
 500 
 
 24640 
 
 
 ■■^1 
 
 
 
 
 
 
 
 
 
 112 
 
 7560 
 
 
 
 283 
 
 15869 
 
 
 
 
 
 TABLE IV. — Corvettes, Sloops, and Despatch Gun-vessels fitted and 
 fitting with the Screw- Propeller in Her Majesty's Service. 
 
 
 Name. 
 
 Guns. 
 
 1 Horse 
 Power. 
 
 
 Name. 
 
 ^ Guns. 1 
 
 Horse 
 Power. 
 
 
 Name. 
 
 j Guns, j 
 
 15 ^" 
 
 1 
 
 Alacrity . . 
 
 
 200 
 
 
 Bt. forward . 
 
 305 
 
 5700 
 
 
 Bt. forward . 
 
 541 
 
 1090 
 
 2 
 
 Alert . 
 
 16 
 
 100 
 
 27 
 
 Flying Fish . 
 
 6 
 
 350 
 
 52 
 
 Plumper 
 
 9 
 
 600 
 
 3 
 
 Ariel . . . 
 
 9 
 
 60 
 
 2.S 
 
 Fox Hound . 
 
 4 
 
 200 
 
 53 
 
 Pylades . . 
 
 20 
 
 350 
 
 4 
 
 Archer . 
 
 14 
 
 202 
 
 29 
 
 Harrier . 
 
 17 
 
 100 
 
 54 
 
 Rattler . 
 
 11 
 
 200 
 
 5 
 
 Arrow , . 
 
 4 
 
 160 
 
 30 
 
 Hesperus . . 
 
 
 120 
 
 55 
 
 Recruit . . 
 
 6 
 
 160 
 
 6 
 
 Assurance 
 
 4 
 
 200 
 
 31 
 
 Highflyers 
 
 2\ 
 
 250 
 
 56 
 
 Renard . 
 
 4 
 
 200 
 
 7 
 
 Beagle . . 
 
 4 
 
 160 
 
 32 
 
 Hornet . . 
 
 17 
 
 100 
 
 57 
 
 Rifleman . . 
 
 8 
 
 100 
 
 8 
 
 Brisk . 
 
 14 
 
 250 
 
 33 
 
 Icarus . 
 
 
 
 58 
 
 Ringdove 
 
 4 
 
 200 
 
 9 
 
 Cadmus . . 
 
 20 
 
 400 
 
 34 
 
 Intrepid . . 
 
 6 
 
 350 
 
 59 
 
 Roebuck. . . 
 
 6 
 
 350 
 
 10 
 
 Cameleon 
 
 16 
 
 100 
 
 35 
 
 Lapwing 
 
 4 
 
 200 
 
 60 
 
 Reward . 
 
 4 
 
 200 
 
 11 
 
 Challenger 
 
 20 
 
 400 
 
 30 
 
 Lynx . . . 
 
 4 
 
 160 
 
 61 
 
 Satellite . 
 
 20 
 
 400 
 
 12 
 
 Charybdis 
 
 20 
 
 400 
 
 37 
 
 Lyra 
 
 8 
 
 60 
 
 62 
 
 Scout . . . 
 
 20 
 
 400 
 
 la 
 
 Clio . . . 
 
 20 
 
 400 
 
 38 
 
 Malacca . . 
 
 17 
 
 200 
 
 63 
 
 Scylla . 
 
 20 
 
 400 
 
 14 
 
 Conflict . 
 
 8 
 
 400 
 
 39 
 
 Minx 
 
 3 
 
 10 
 
 64 
 
 Sharpshooter . 
 
 8 
 
 202 
 
 15 
 
 Coquette . . 
 
 4 
 
 200 
 
 40 
 
 Miranda . . 
 
 14 
 
 250 
 
 65 
 
 Snake . . 
 
 4 
 
 160 
 
 IC 
 
 Cordelia . 
 
 8 
 
 60 
 
 41 
 
 Mohawk 
 
 4 
 
 200 
 
 66 
 
 Sparrowhawk. 
 
 4 
 
 200 
 
 17 
 
 Cormorant 
 
 4 
 
 200 
 
 42 
 
 Mutine . . 
 
 16 
 
 100 
 
 67 
 
 Surprise . 
 
 4 
 
 200 
 
 18 
 
 Cossack . 
 
 20 
 
 250 
 
 43 
 
 Myrmidon 
 
 3 
 
 150 
 
 68 
 
 Swallow . . 
 
 9 
 
 60 
 
 19 
 
 Cruiser , . 
 
 17 
 
 60 
 
 44 
 
 Niger . . . 
 
 14 
 
 400 
 
 69 
 
 Tartar . 
 
 20 
 
 250 
 
 20 
 
 Curlew . 
 
 9 
 
 60 
 
 45 
 
 Nimrod . , . 
 
 6 
 
 350 
 
 70 
 
 Teazer . . 
 
 3 
 
 40 
 
 21 
 
 Desperate . . 
 
 8 
 
 400 
 
 46 
 
 Osprey . . . 
 
 4 
 
 200 
 
 71 
 
 Victor 
 
 6 
 
 350 
 
 22 
 
 Encounter 
 
 14 
 
 360 
 
 47 
 
 Pearl 
 
 20 
 
 400 
 
 72 
 
 Vigilant . . 
 
 4 
 
 200 
 
 23 
 
 Esk . . . 
 
 21 
 
 250 
 
 48 
 
 Pelican . . 
 
 16 
 
 100 
 
 73 
 
 Viper 
 
 4 
 
 160 
 
 24 
 
 Etna . . 
 
 14 
 
 200 
 
 49 
 
 Pelorus . 
 
 20 
 
 400 
 
 74 
 
 Wanderer . . 
 
 4 
 
 200 
 
 25 
 
 Falcon . . 
 
 17 
 
 100 
 
 50 
 
 Phoenix . 
 
 6 
 
 200 
 
 75 
 
 Wasp 
 
 14 
 
 100 
 
 26 
 
 Fawn 
 
 
 128 
 
 51 
 
 Pioneer . . 
 
 6 
 
 350 
 
 76 
 
 Wrangler . . 
 
 4 
 
 160 
 
 
 
 305 
 
 5700 
 
 
 
 541 
 
 10900 
 
 
 Total . . 
 
 761 
 
 16202 
 
 175 
 
TABLE —Trooper, Store-ships, Water-tanks, Flour-mills, Yachts, and 
 Floating -factories. 
 
 
 Name. 
 
 1 Guns. 1 
 
 Horse 
 Power. 
 
 
 Name. 
 
 1 Guns. 1 
 
 Horse 
 Power. 
 
 
 Name. 
 
 03 
 
 5 
 
 Horse 
 Power. 
 
 
 AbHiiciaiice * 
 
 
 100 
 
 
 Bt. forward . 
 
 
 1856 
 
 — 
 
 Et. forward . 
 
 — 
 11 
 
 4076 
 
 2 
 
 Assistance • 
 
 
 400 
 
 '18 
 
 Hearty 
 
 
 100 
 
 34 
 
 Prospero . 
 
 
 144 
 
 3 
 
 
 
 100 
 
 10 
 
 Helen Faucit . 
 
 
 
 35 
 
 Resistance . . 
 
 10 
 
 400 
 
 
 
 
 100 
 
 20 
 
 Himalaya 
 
 
 700 
 
 36 
 
 Resolute . 
 
 
 400 
 
 
 
 
 90 
 
 21 
 
 Humber . 
 
 
 30 
 
 37 
 
 Simoom . . 
 
 s 
 
 350 
 
 
 liniiser • , 
 
 
 100 
 
 2i 
 
 Industry 
 
 
 80 
 
 38 
 
 Spriglitly . 
 
 
 100 
 
 
 jjuuaio 
 
 
 60 
 
 23 
 
 Malta 
 
 
 50 
 
 39 
 
 Supply . . 
 
 2 
 
 80 
 
 g 
 
 LJusLiei • , 
 
 
 
 24 
 
 Megger a . . 
 
 
 350 
 
 40 
 
 SuUna 
 
 
 
 g 
 
 Chasseur 
 
 
 100 
 
 25 
 
 Monkey . 
 
 
 130 
 
 41 
 
 Sultana . . 
 
 
 
 10 
 
 (Joiihauce . 
 
 
 100 
 
 26 
 
 Moslem 
 
 
 120 
 
 42 
 
 Thais 
 
 
 'so 
 
 
 Coromaudel 
 
 
 
 27 
 
 Myrtle 
 
 
 50 
 
 43 
 
 Torch . . . 
 
 
 150 
 
 12 
 
 Crescent . 
 
 
 *50 
 
 28 
 
 Nimble 
 
 
 
 44 
 
 Transit . 
 
 
 500 
 
 13 
 
 
 
 
 iv 
 
 Pera . 
 
 
 'so 
 
 45 
 
 U i"gent . . 
 
 
 450 
 
 14 
 
 Fnbo 
 
 
 iio 
 
 30 
 
 Perseverance . 
 
 
 360 
 
 46 
 
 Vulcan . 
 
 'e 
 
 350 
 
 Ic 
 
 Elfiu . . . 
 
 
 140 
 
 31 
 
 Pike . 
 
 
 50 
 
 47 
 
 Wye . . . 
 
 
 100 
 
 16 
 
 1 eai-lcss . 
 
 
 76 
 
 3i 
 
 Pigeon . . . 
 
 
 50 
 
 
 
 
 
 
 
 
 
 
 
 
 
 17 
 
 Fox . . . 
 
 
 200 
 
 33 
 
 Princess Alice . 
 
 i 
 
 120 
 
 
 Total 
 
 37 
 
 7300 
 
 
 
 
 1856 
 
 
 
 11 
 
 4076 
 
 
 
 
 
 TABLE VL 
 
 Statement of the Total Nuniber 
 and Power of Steam Gun-boats 
 in the Royal Navy on the \st 
 April, 1856. 
 
 No. 
 
 Guns. 
 
 It 
 
 Total 
 Guns. 
 
 Total 
 Horse 
 Power. 
 
 122 
 
 4 
 
 60 
 
 488 
 
 7320 
 
 13 
 
 4 
 
 40 
 
 52 
 
 520 
 
 20 
 
 2 
 
 20 
 
 40 
 
 400 
 
 155 
 
 10 
 
 120 
 
 580 
 
 8240 
 
 TABLE Vn. 
 
 'Statement of the Number and Power 
 of Steam Vessels of all classes in 
 the Royal Navy on the 1st Aprils 
 1856. 
 
 
 
 CO 
 
 
 
 No. 
 
 a 
 
 1' 
 
 
 
 o 
 
 
 Line-of-Battlc Ships 
 
 43 
 
 3797 
 
 22950 
 
 Frigates & Mortar-ships. 
 
 24 
 
 889 
 
 10560 
 
 Paddle-wheel Vessels 
 
 90 
 
 500 
 
 24640 
 
 Corvettes, Sloops, &c. . 
 
 76 
 
 761 
 
 16202 
 
 Troop-ships . . . 
 
 47 
 
 37 
 
 7300 
 
 Gun-boats . . 
 
 155 
 
 580 
 
 8240 
 
 
 435 
 
 6564 
 
 89892 
 
 TABLE VIII. — Shoioing the number of vessels {wood and iron) belonging to 
 the Mail Contract Steam Packet Companies in March, 1853; also their 
 Tonnage and Horse Power, from Parliamentary return ordered to he 
 'printed 2 ^h June, 1853. 
 
 
 Number of Vessels. 
 
 Tonnage. 
 
 Horse Power, 
 
 1 To what Company 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 belonging. 
 
 Wood. 
 
 Iron. 
 
 Total. 
 
 Wood. 
 
 Iron. 
 
 Total. 
 
 Wood. 
 
 Iron. 
 
 Total. 
 
 1 
 
 Peninsula and Oriental 
 
 11 
 
 22 
 
 33 
 
 11800 
 
 26449 
 
 38249 
 
 4086 
 
 7481 
 
 11567 
 
 Royal West India . . 
 
 19 
 
 1 
 
 20 
 
 32612 
 
 2700 
 
 35312 
 
 8750 
 
 800 
 
 9550 
 
 British and N. American 
 
 8 
 
 1 
 
 9 
 
 • 14991 
 
 2500 
 
 17491 
 
 5690 
 
 1000 
 
 6C90 
 
 Pacific .... 
 
 
 8 
 
 8 
 
 
 6688 
 
 6688 
 
 
 2298 
 
 2298 
 
 General Screw Steam )_ 
 
 
 8 
 
 8 
 
 
 13496 
 
 13496 
 
 
 2250 
 
 2250 
 
 Shipping . . j" 
 
 
 
 
 
 
 
 
 
 Australian . 
 
 
 5 
 
 5 
 
 
 8600 
 
 8600 
 
 
 1800 
 
 1800 
 
 South Western . . 
 
 
 4 
 
 4 
 
 
 1612 
 
 1612 
 
 
 677 
 
 677 
 
 African 
 
 
 4 
 
 4 
 
 
 3920 
 
 3920 
 
 
 530 
 
 530 
 
 Total . . . 
 
 38 
 
 53 
 
 
 59403 
 
 65965 
 
 
 18526 
 
 16836 
 
 
 
 Grand total 
 
 91 
 
 Grand total 
 
 125368 
 
 Grand total 
 
 35362 
 
 176 
 
Fig. 4, 
 
 Fig 5. 
 
 THUNDER AND LIGHTNING, AND THE 
 AURORA BOREALIS. 
 
 i. Atmosplieric Electricity. — 2. The air generally charged with positive 
 electricity. — 3. Subject to variations and exceptions. — 4. Diurnal 
 variations of electrical intensity. Observations of Quetelet. — 5. 
 Irregular and local variations and exceptions, — 6. Variations 
 dependent on the season and weather. — 7. Methods of observing 
 atmospheric electricity. — 8. Methods of ascertaining the electrical 
 condition of the higher strata. — 9. Remarkable experiments ol 
 Eomas, 1757. — 10. Electrical charge of clouds varies. — 11. Thunder 
 and lightning, — 12, Form and extent of the flash of lightning. — 13. 
 €ause of the rolling of thunder. — 14. Affected by the zigzag form of 
 lightning. — 15. Affected by the varying distance of different parts of 
 the flash. — 16. Affected by echo and by interference. — 17. Inductive 
 action of clouds on the earth. — 18. Formation of Fulgurites explained. 
 — 19. Accidents of the surface which attract lightning. — 20. Lightning 
 follows conductors by preference — its effects on buildings. — 21. Con- 
 
 Lardner's Museum of Soibnoe. n 177 
 
 No. 130, 
 
THUNDER AKD LIGHTNING. 
 
 ductors or paratonneiTes for the protection of buildings. — 22. Effects 
 of lightning on bodies which it strikes. — 23. The Aurora Borealis 
 — the phenomena unexplained. — 24. General character of the 
 meteor. — 25. Description of auroras seen in the polar regions by 
 M. Lottin. 
 
 1. There is no part of physical science in wMcli the researches 
 of modern investigators have been attended with such signal 
 success, as those which have been directed to the discovery of the 
 in£uen-ce of electricity upon the atmosphere. Indeed it would be 
 difficult to name any atmospheric change, which is not directly or 
 indirectly connected with electric agency. It is true that these 
 atmospheric phenomena, fugitive and transitory as most of them 
 are, have not been in all cases traced with clearness and cer- 
 tainty to their causes, that the relation of some of them to the 
 agency of electricity is rendered probable, more from general 
 appearances than by distinct and satisfactory demonstration, and 
 that some of them, which are evidently of electric origin, have, 
 nevertheless, remained unexplained by, or not reduced to, any of 
 the known laws which govern that physical agent. Still there is 
 much that falls under the general principles of electric science, 
 and those phenomena which remain with or without any satis- 
 factory explanation require to be stated, tliat those who 
 pursue this part of physical science, with a view to extend its 
 limits, may be guided to proper subjects of observation and 
 investigation. 
 
 How important the topics embraced under the general head of 
 atmospheric electricity are, will be understood when it is stated, 
 that upon the electric condition of the atmosphere, and the 
 changes incidental to it, depend not only the stupendous phe- 
 nomena of thunder-storms, but also the whole of that beautiful 
 and interesting class of phenomena comprised under the general 
 name of Aurora Borealis. 
 
 2. The terrestrial globe which we inhabit is invested with an 
 ocean of air, the depth of which is about the 200th part of its 
 diameter. It may, therefore, be conceived by imagining a coat- 
 ing of air, the tenth of an inch thick, investing a twenty-inch 
 globe. This aerial ocean, relatively shallow as it is, at the 
 bottom of which the tribes of organised nature have their 
 dwelling, is, nevertheless, the theatre of stupendous electrical 
 phenomena. 
 
 It may be stated as a general fact, that the atmosphere which 
 thus covers the globe is charged with positive electricity, which, 
 acting by induction on the superficial stratum of the globe on 
 which it rests, decomposes the natural electricity, attracting the 
 negative fluid to the surface and repelling the positive fluid to 
 178 
 
ELECTRIC STATE OF THE AIR. 
 
 tlie inferior strata. The globe and its atmosphere may therefore 
 be not inaptly compared to a Leyden phial, the outer coating of 
 which being placed in connection with the prime conductor of a 
 machine, is charged with positive electricity, and the inner coating 
 being in connection with the ground, is charged by induction with 
 negative electricity. The outer coating represents the atmosphere, 
 and the inner the superficial stratum of the globe. 
 
 3. This normal state of the general atmospheric ocean is 
 subject to variations and exceptions, variations of intensity and 
 exceptions in quality or name. The variations are periodical and 
 accidental. The exceptions local, patches of the general atmos- 
 phere in which clouds float being occasionally charged with 
 negative electricity. 
 
 4. The intensity of the electricity with which the atmosphere 
 is charged, varies, in the course of twenty-four hours, alternately 
 increasing and decreasing. M. duetelet found that the first 
 maximum was manifested about 8 a.m., and the second about 
 9 P.M. The minimum in the day was at 3 p.m. He found 
 also that the mean intensity was greatest in January and least 
 in June. 
 
 5. Such are the normal changes which the electrical condition 
 of the air undergoes when the atmosphere is clear and unclouded. 
 "When, however, the firmament is covered with clouds, the elec- 
 tricity is subject during the day to frequent and irregular changes 
 not only in intensity but in name ; the electricity being often 
 negative, owing to the presence of clouds over the place of 
 observation, charged, some with positive, and some with negative 
 electricity. 
 
 6. The intensity of the electricity of the air is also affected by 
 the season of the year, and by the prevalent character and 
 direction of the winds ; it varies also with the elevation of the 
 strata, being in general greater in the higher than in the lower 
 regions of the atmosphere. The intensity is generally greater in 
 winter, and especially in frosty weather, than in summer, and 
 when the air is calm than when winds prevail. 
 
 Atmospheric deposits, such as rain, hail, snow, &c., are some- 
 times positive and sometimes negative, varying with the direction 
 of the wind. North winds give positive, and south winds negative 
 deposits. 
 
 7. The electricity of the atmosphere is observed by erecting in 
 it, to any desired elevation, pointed metallic conductors, from the 
 lower extremities of which wires are carried to electroscopes of 
 various forms, according to the intensity of the electricity to be 
 observed. So immediate is the increase of electrical tension in 
 rising through the strata of the air, that a gold leaf electroscope, 
 
 . N 2 179 
 
THUNDER AND LIGHTNING. 
 
 properly adapted to the purpose, and reduced to its natural state 
 when placed horizontally on the ground, will show a sensible 
 divergence when raised to the level of the eyes. 
 
 8. To ascertain the electrical condition of strata too elevated 
 to be reached by a fixed conductor, the extremity of a flexible 
 wire, to which a metallic point is attached, is connected with a 
 lieavy ball, which is projected into the air by a gun or pistol, or 
 to an arrow projected by a bow. The projectile, when it attains 
 the limit of its flight, detaches the wire from the electroscope, 
 which then indicates the electrical state of the air at the highest 
 point attained by the projectile. 
 
 9. The vast quantities of electricity with which the clouds are 
 sometimes charged, were rendered manifest in a striking manner 
 by the well-known experiments made by means of kites by Eomas 
 in 1757. The kite, carrying a metallic point, was elevated to the 
 strata in which the electric cloud floated. A wire was connected 
 with the cord, and carried from the pointed conductor borne by 
 the kite to a part of the cord at some distance from the lower 
 extremity, where it was turned aside and brought into connection 
 with an electroscope, or other experimental means of testing the 
 quantity and quality of the electricity with which it was charged. 
 Romas drew from the extremity of this conducting wire not only 
 strong electric sparks, but blades of fire nine or ten feet in length, 
 and an inch in thickness, the discharge of which was attended 
 with a report as loud as that of a pistol. In less time than an 
 hour, not less than thirty flashes of this magnitude and intensity 
 were often drawn from the conductor, besides many of six or seven 
 feet and of less length. 
 
 10. It has been shown by means of kites thus applied, that the 
 clouds are charged some with positive and some with negative 
 electricity, while some are observed to be in their natural state. 
 These circumstances serve to explain some phenomena observed 
 in the motions of the clouds which are manifested in stormy 
 weather. Clouds which are similarly electrified repel, and those 
 which are oppositely electrified attract each other. Hence arise 
 motions among such clouds of the most opposite and complicated 
 kind. While they are thus reciprocally attracted and repelled in 
 virtue of the electricity with which they are charged, they are 
 also transported in various directions by the currents which pre- 
 vail in the atmospheric strata in which they float, these currents 
 often having themselves different directions. 
 
 11. Such appearances are the sure prognostics of a thunder- 
 storm. Clouds charged with contrary electricities affect each 
 other by induction, and mutually attract, whether they float in 
 the same stratum or in strata at different elevations. When they 
 
 180 
 
FOEM AND LENGTH OB^ FLASH. 
 
 come within striking distance, the contrary fluids rush to each 
 other, and an electrical discharge takes place. 
 
 The clouds, however, unlike the metallic coatings of the jar, 
 arc very imperfect conductors, and consequently, when discharged 
 at one part of their vast extent, they preserve elsewhere their 
 electricity in its original intensity. Thus, the first discharge, 
 instead of establishing equilibrium, rather disturbs it, for the 
 part of the cloud which is still charged is alone attracted by the 
 part of the other cloud in which the fluid has not yet been 
 neutralised. Hence arise various and complicated motions and 
 variations of form of the clouds, and a succession of discharges 
 between the same clouds must take placa before the electrical 
 equilibrium is established. This is necessarily attended by a corre- 
 sponding succession of flashes of lightning and claps of thunder. 
 
 12. The form of the flash in the case of lightning, like that of 
 the spark taken from an* electrified conductor, is zigzag. The 
 doublings or acute angles formed at the successive points when 
 the flash changes its direction vary in number and proximity. 
 The cause of this zigzag course, whether of the electric spark or 
 of lightning, has not been explained in any clear or satisfactory 
 manner. 
 
 The length of the flashes of lightning also varies ; in some 
 cases they have been ascertained to extend to from two-and-a- 
 half to three miles. It is probable, if not certain, that the line 
 of light exhibited by flashes of forked lightning are not in reality 
 one continued line simultaneously luminous, but that on the con- 
 trary the light is developed successively as the electricity proceeds 
 in its course, the appearance of a continuous line of light being an. 
 optical efiect, analogous to the continuous line of light exhibited 
 when a lighted stick is moved rapidly in a circle, the same 
 explanation being applicable to the case of lightning. 
 * 13. As the sound of thunder is produced by the passage of the 
 electric fluid through the air which it suddenly compresses, it is 
 evolved progressively along the entire space along which the 
 lightning moves. But since sound moves only at the rate of 1100 
 feet per second, while the transmission of light is so rapid that 
 in this case it may be considered as practically instantaneous, the 
 sound will not reach the ear for an interval greater or less after 
 the perception of the light, just as the flash of a gun is seen before 
 the report is heard. 
 
 By noting the interval, therefore, which elapses between tlie 
 perception of the flash and that of the sound, the distance of 
 the point where the discharge takes place can be computed 
 approximately, by allowing 1100 feet for every second in the 
 interval. 
 
 181 
 
THUNDER AND LIGHTNING. 
 
 But since a separate sound is produced at every point tlirougli 
 ■which, the flash passes, and as these points are at distances from 
 the observer which vary according to the position, length, 
 direction, and form of the flash, it will follow necessarily that the 
 sounds produced by the same flash, though practically simul- 
 taneous, because of the great velocity with which the electricity 
 moves, arrive at the ear in comparatively slow succession. 
 
 The varying loudness of the successive sounds heard in the 
 rolling of thunder, proceeds in part from the same causes as the 
 varying intensity of the light of the flash. But it may, perhaps, 
 be more satisfactorily explained by the combination of the suc- 
 cessive discharges of the same cloud, rapidly succeeding each 
 other, and combining their effects with those arising from the 
 varying distances of different parts of the same flash. 
 
 14. It appears to us that the varying intensity of the roUing of 
 thunder may also be very clearly and satisfactorily explained by 
 the zigzag form of the flash, combined with the efiect of the 
 varying distance ; and it seems extraordinary that an explanation 
 so obvious has not been suggested. Let a, b, c, d (fig. 1), be a 
 
 Fig. 1. 
 
 part of a zigzag flash seen by an observer at o. Taking o as a 
 centre, suppose arcs c c and b 6 of circles to be drawn, with o c 
 and 0 B as radii. It is clear that the points c and c, and b and b, 
 being respectively equally distant from the observer, the sounds 
 produced there will be heard simultaneously, and, supposing 
 them equal, will produce the perception of a sound twice as loud 
 as either heard alone would do. All the points on the zigzag 
 c B c 6 are so placed that three of them are equi-distant from o. 
 Thus, if with o as centre, and o m as radius, a circular arc be 
 described, it will intersect the path of the lightning at three 
 points m, m% and m", and these three points being, therefore, at 
 the same distance from o, the sounds produced at them will 
 reach the observer at the same moment, and if they be equally 
 intense wUl produce on the ear the same effect as a single 
 sound three times as loud. The same will be true for all the 
 points of the zigzag between c and h. Thus, in this case, 
 182 
 
CAUSE OF THE ROLLma OF THUNDER. 
 
 supposing the intensity of the lightning to be uniform from a to 
 D, there will be three degrees of loudness in the sound produced, 
 the least between a and c and between h and d, the greatest 
 between c and h along the zigzag, and the intermediate at the 
 points c c and b h. 
 
 It is evident, that from the infinite variety of form and position 
 with relation to the observer, of which the course of the lightning 
 is susceptible, the variations of intensity of the rolling of thunder 
 which may be explained in this way have no limit. 
 
 15. Since the loudness of a sound diminishes as the square of 
 the distance of the observer is increased, it is clear that this affords 
 another means of explaining the varying loudness of the rolling of 
 thunder. 
 
 16. As the rolling of thunder is much more varied and of 
 longer continuance in mountainous regions than in open plain 
 •countries, it is no doubt also affected by reverberation from every 
 surface capable of reflecting sound, which it encounters. A 
 part therefore of the rolling must be in such cases the effect 
 of echo. 
 
 It has been also conjectured that the acoustic effects are 
 modified by the effects of interference. 
 
 17. A cloud charged with electricity, whatever be the quality of 
 the fluid or the state of the atmosphere around it, exercises by 
 induction an action on all bodies upon the earth's surface imme- 
 diately under it. It has a tendency to decompose their natural 
 electricity, repelling the fluid of the same name, and attracting to 
 the highest points the fluid of a contrary name. The effects thus 
 actually produced upon objects exposed to such induction, will 
 depend on the intensity and quality of the electricity with which 
 the cloud is charged, its distance, the conductibility of the 
 materials of which the bodies affected consist, their magnitude, 
 position, and, above all, their form. 
 
 "Water being a much better conductor than earth in any state 
 of aggregation, thunder clouds act with great energy on the sea, 
 lakes, and other large collections of water. The flash has a 
 tendency to pass between the cloud and the water, just as the 
 spark passes between the conductor of an electric machine and the 
 hand presented to it. 
 
 18. This explains the fact that lightning sometimes penetrates 
 strata of the solid ground, under which subterranean reservoirs of 
 water are found. The water of such reservoirs is affected by the 
 inductive action of an electrified cloud, and in its turn reacts 
 upon the cloud, as one coating of a Ley den jar reacts upon the 
 other. When this mutual action is sufficiently strong to over- 
 come the resistance of the subjacent atmosphere, and the strata of 
 
 183 
 
THUNDER AND LIGHTNING. 
 
 soil under wMcli tlie subterranean reservoir lies, a discharge 
 takes place, and the lightning penetrates the strata, fusing the 
 materials of which it is composed, and leaving a tubular hole with 
 a hard vitrified coating. 
 
 Tubes thus formed have been called fulgurites, or thunder 
 tubes. 
 
 19. The well known properties of points, edges, and other 
 projecting parts of conductors, will render easily intelligible the 
 influence of mountains, peaked hills, projecting rocks, trees, 
 lofty edifices, and other objects, natural and artificial, which 
 project upwards from the general surface of the ground. 
 Lightning never strikes the bottom of deep and close valleys. 
 In Switzerland, on the slopes of the Alps and Pyrenees, and in 
 other mountainous countries, multitudes of cultivated valleys are 
 found, the inhabitants of which know by secular tradition that 
 they have nothing to fear from thunder-storms. If, however, the 
 width of the valleys were so great as twenty or thirty times their 
 depth, clouds would occasionally descend upon them in masses 
 sufficiently considerable, and lightning would strike. 
 
 Solitary hills, or elevated buildings rising in the centre of an 
 extensive plain, are peculiarly exposed to lightning, since there 
 are no other projecting objects near them to divert its course. 
 
 Trees, especially if they stand singly apart from others, are 
 likely to be struck. Being from their nature more or less im- 
 pregnated with sap, which is a conductor of electricity, they 
 attract the fluid, and are struck. 
 
 The effects of such objects are, however, sometimes modified by 
 the agency of unseen causes below the surface. The condition of 
 the soil, subsoil, and even the inferior strata, the depth of the 
 roots and their dimensions, also exercise considerable influence on 
 the phenomena, so that in the places where there is the greatest 
 apparent safety there is often the greatest danger. It is, never- 
 theless, a good general maxim not to take a position in a thunder- 
 storm either under a tree or close to an elevated building, but to 
 keep as much as possible in the open plain. 
 
 20. Lightning falling upon buildings chooses by preference the 
 points which are the best conductors. It sometimes strikes and 
 destroys objects which are non-conductors, but this happens 
 generally when such bodies lie in its direct course towards con- 
 ductors. Thus lightning has been found to penetrate a wall 
 attracted by a mass of metal placed within it. 
 
 Metallic roofs, beams, braces, and other parts in buildings, are 
 liable thus to attract lightning. The heated and rarefied air in 
 chimneys acquires conductibility. Hence it happens often that 
 lightning descends chimneys, and thus passes into rooms. It 
 184 
 
LIGHTNING CONDUCTOK. 
 
 Fig. 2. 
 
 follows bell- wires, metallic mouldings of walls and furniture, and 
 fuses gilding. 
 
 21. The purpose of paratonnerres or conductors, erected for the 
 protection of buildings, is not to repel, but 
 rather to attract lightning, and divert it into 
 a course in which it will be innoxious. 
 
 A paratonnerre is a pointed metallic rod, 
 the length of which varies with the building 
 on which it is placed, but which is generally 
 from thirty to forty feet. It is erected ver- 
 tically over the object it is intended to pro- 
 tect. From its base an unbroken series of 
 metallic bars, soldered or welded together 
 end to end, are continued to the ground, 
 where they are buried in moist soil, or, 
 better still, immersed in water, so as to faci- 
 litate the escape of the fluid which descends 
 upon them. If water, or moist soil, cannot be 
 conveniently found, it should be connected 
 with a sheet of metal of considerable super- 
 ficial magnitude, buried in a pit filled with 
 pounded charcoal, or, better still, with braise. 
 
 The parts of a well-constructed paratonnerre 
 are represented in fig. 2. The rod, which is of 
 iron, is round at its base, then square, and 
 decreases gradually in thickness to the summit. 
 It is composed commonly of three pieces closely 
 jointed together, and secured by pins passed 
 transversely through them. In the figure are 
 represented only the two extremities of the 
 lowest, and those of the intermediate piece, to 
 avoid giving inconvenient magnitude to the 
 diagram. The superior piece, g, is represented 
 complete. It is a rod of brass or copper, 
 about two feet in length, terminating in a 
 platinum point about three inches long, at- 
 tached to the rod by silver solder, which is 
 further secured by a brass ferule, which gives 
 the projecting appearance in the diagram below 
 the point. 
 
 Three of the methods, reputed the most 
 efficient for attaching the paratonnerre to the 
 roof, are represented in fig. 3, at p, I, and /. 
 At p the rod is supported against a vertical piece, to which it 
 is attached by stirrups ; at Z it is bolted upon a diagonal brace 
 
 185 
 
THUNDER AND LIGHTNING. 
 
 and at / it is simply secured by bolts to a horizontal beam 
 through which it passes. The last is evidently the least solid 
 method of fixing it. 
 
 Fig. 3. 
 
 The conductor is continued downwards along the wall of the 
 'edifice, or in any other convenient course, to the ground, either 
 by bars of iron, round or square, or by a cable of iron or copper 
 wires, such as is sometimes used for the lighter sort of suspension 
 bridges. This is attached, at its upper extremity, to the base of 
 the paratonnerre by a joint, which is hermetically closed, so as to 
 prevent oxidation, which would produce a dangerous solution of 
 continuity. 
 
 To comprehend the protective influence of this apparatus, it 
 must be considered that the inductive action of a thunder-cloud 
 decomposes the natural electricity of the rod, more energetically 
 than that of surrounding objects, both on account of the material 
 and the form of the rod. The point becoming surcharged with 
 the fluid of a contrary name from that of the cloud suspended over 
 it, discharges this fluid in a jet towards the cloud, where it 
 •combines with and neutralises an equal quantity of the electricity 
 with which the cloud is charged, and, by the continuance of this 
 process, ultimately reduces the cloud to its natural state. 
 
 It is therefore more correct to say that the paratonnerre draws 
 electricity from the ground and projects it to the cloud, than that 
 it draws it from the cloud and transmits it to the earth. 
 
 It is evidently desirable that all conducting bodies to be pro- 
 tected by the paratonnerre, should be placed in metallic connection 
 with it, since in that case their electricity, decomposed by the 
 inductive action of the clouds, will necessarily escape by the 
 conductor either to the earth or to the cloud by the point. 
 186 
 
EFFECTS OF LIGHTNING. 
 
 It is considered generally that the range of protection of a 
 paratonnerre is a circle round its base, whose radius is two or 
 three times its length. 
 
 22. The effects of lightning, like those of electricity evolved 
 by artificial means, are threefold, physiological, physical, and 
 mechanical. 
 
 When lightning kills, the parts where it has struck bear the 
 marks of severe burning ; the bones are often broken and crushed 
 as if they had been subjected to violent mechanical pressure. 
 When it acts on the system by induction only, which is called the 
 secondary or indirect shock, it does not immediately kill, but 
 inflicts nervous shocks so severe as sometimes to leave effects 
 which are incurable. 
 
 The physical effects of lightning produced upon conductors is 
 to raise their temperature. This elevation is sometimes so great 
 that they are rendered incandescent, fused, and even burned. 
 This happens occasionally with bell- wires, especially in exposed 
 and unprotected positions, as in courts or gardens. The drops of 
 molten metal produced in such cases set fire to any combustible 
 matter on which they may chance to fall. Wood, straw, and such 
 non-conducting bodies are ignited generally by the lightning 
 drawn through them, by the attraction of other bodies near them 
 which are good conductors. 
 
 The mechanical effects of lightning, the physical cause of which 
 has not been satisfactorily explained, are very extraordinary. 
 Enormous masses of metal are torn from their supports, vast 
 blocks of stone are broken, and massive buildings are razed to the 
 ground. 
 
 23. No theory or hypothesis which has commanded genera 
 acceptation, has yet been suggested for the explanation of the 
 Aurora Borealis. All the appearances which attend the pheno- 
 menon are, however, electrical; and its forms, directions, and 
 positions, though ever varying, always bear a remarkable relation 
 to the magnetic meridians and poles. Whatever, therefore, be 
 its physical cause, it is evident that the theatre of its action is the 
 atmosphere ; and that the agent to which the development is due, is 
 electricity, influenced in some unascertained manner by terrestrial 
 magnetism. In the absence of any satisfactory theory for the 
 explanation of the phenon^enon, we shall confine ourselves here to 
 a short description of it, derived from the most extensive and 
 exact series of observations which have been made in those 
 regions, where the meteor has been seen with the most marked 
 characters and in the greatest splendour. 
 
 24. The Aurora Borealis is a luminous phenomenon which 
 appears in the heavens, and is seen in high latitudes in both 
 
 187 
 
THUNDER AND LIGHTNING. 
 
 hemispheres. The term Aurora Borealis, or Northern Lights, has 
 been applied to it, because the opportunities of witnessing it are^ 
 from the geographical character of the globe, much more frequent 
 in the northern than in the southern hemisphere. The term 
 aurora polar is would be a more proper designation. 
 
 This phenomenon consists of luminous rays of various colours, 
 issuing from every direction, but converging to the same point, 
 which appear after sunset generally toward the north, occasionally 
 toward the west, and sometimes, but rarely, toward the south. 
 It frequently appears near the horizon, as a vague and diffused 
 light, something like the faint streaks which harbinger the rising 
 sun and form the dawn. Hence the phenomenon has derived its 
 name, which signifies northern morning. Sometimes, however, it 
 is presented under the form of a sombre cloud, from which luminous 
 jets issue, which are often variously coloured, and illuminate the 
 entire atmosphere. 
 
 The more conspicuous auroras commence to be formed soon 
 after the close of twilight. At first a dark mist or foggy cloud is 
 perceived in the north, and a little more brightness towards the 
 west than in the other parts of the heavens. The mist gradually 
 takes the form of a circular segment, resting at each corner on the 
 horizon. The visible part of the arc soon becomes surrounded 
 with a pale light, which is followed by the formation of one or 
 several luminous arcs. Then come jets and rays of light variously 
 coloured, which issue from the dark part of the segment, the 
 continuity of which is broken by bright emanations, indicating a 
 movement of the mass, which seems agitated by internal shocks, 
 during the formation of these luminous radiations, that issue from 
 it as flames do from a conflagration. When this species of fire 
 has ceased, and the aurora has become extended, a crown is 
 formed at the zenith, to which these rays converge. From this 
 time the phenomenon diminishes in its intensity, exhibiting, 
 nevertheless, from time to time, sometimes on one side of the 
 heavens and sometimes on another, jets of light, a crown, and 
 colours more or less vivid. Finally the motion ceases, the light 
 approaches gradually to the horizon ; and the cloud, quitting the 
 other parts of the firmament, settles in the north. The dark part 
 of the segment becomes luminous, its brightness being greatest 
 near the horizon, and becoming more feeble as the altitude 
 augments, until it loses its light altogether. 
 
 The aurora is sometimes composed of two luminous segments, 
 which are concentric, and separated from each other by one dark 
 space, and from the earth by another. Sometimes, though rarely, 
 there is only one dark segment, which is symmetrically pierced 
 round its border by openings, through which light or fire is seen. 
 188 
 
AURORA BOREALIS. 
 
 25. One of the most recent and exact descriptions of this meteor 
 is the following, supplied by M. Lottin, an officer of the French 
 navy, and a member of the Scientific Commission sent some years 
 ago to the North Seas. Between September, 1838, and April, 
 1839, this savant observed nearly 150 meteors of this class. They 
 were most frequent from the 17th November to the 25th January, 
 being the interval during which the sun remained constantly 
 below the horizon. During this period there were sixty-four 
 auroras visible, besides many which a clouded sky concealed 
 from the eye, but the presence of which was indicated by the 
 disturbances they produced upon the magnetic needle. 
 
 The succession of appearances and changes presented by these 
 meteors are thus described by M. Lottin : — 
 
 Between four and eight o'clock, p.m., a light fog, rising to the 
 altitude of six degrees, became coloured on its upper edge, being 
 fringed with the light of the meteor rising behind it. This border 
 becoming gradually more regular, took the form of an arc, of a 
 pale yellow colour, the edges of which were diffuse, the extremities 
 resting on the horizon. This bow swelled slowly upwards, its 
 vertex being constantly on the magnetic meridian. Blackish 
 streaks divided regularly the luminous arc, and resolved it into a 
 system of rays ; these rays were alternately extended and con- 
 tracted ; sometimes slowly, sometimes instantaneously ; some- 
 times they would dart out, increasing and diminishing suddenly 
 in splendour. The inferior parts, or the feet of the rays, pre- 
 sented always the most vivid light, and formed an arc more or 
 less regular. The length of these rays was very various, but they 
 all converged to that point of the heavens, indicated by the direc- 
 tion of the southern pole of the dipping needle. Sometimes they 
 were prolonged to the point where their directions intersected, and 
 formed the summit of an enormous dome of light. 
 
 The bow then would continue to ascend toward the zenith : it 
 would suffer an undulatory motion in its light — that is to say, 
 that from one extremity to the other the brightness of the rays 
 would increase successively in intensity. This luminous current 
 would appear several times in quick succession, and it would pass 
 much more frequently from west to east than in the opposite 
 direction. Sometimes, but rarely, a retrograde motion would 
 take place immediately afterward ; and as soon as this wave of 
 light had run successively over all the rays of the aurora from 
 west to east, it would return, in the contrary direction, to the 
 point of its departure, producing such an effect that it was 
 impossible to say whether the rays themselves were actually 
 affected by a motion of translation in a direction nearly hori- 
 zontal, or if this more vivid light was transferred from ray to ray, 
 
 189 
 
THUNDER AND LIGHTNING. 
 
 tlie system of rays tbemselves suffering no change of position. 
 The bow, thus presenting the appearance of an alternate motion 
 in a direction nearly horizontal, had usually the appearance of the 
 undulations or folds of a ribbon or flag agitated by the wind- 
 Sometimes one, and sometimes both of its extremities would 
 desert the horizon, and then its folds would become more numerou& 
 and marked, the bow would change its character, and assume the 
 form of a long sheet of rays returning into itself, and consisting of 
 several parts forming graceful curves. The brightness of the rays 
 would vary suddenly, sometimes surpassing in splendour stars of 
 the first magnitude ; these rays would rapidly dart out, and curves 
 would be formed and developed like the folds of a serpent ; then 
 the rays would affect various colours, the base would be red, the 
 middle green, and the remainder would preserve its clear yellow 
 hue. Such was the arrangement which the colours always pre- 
 served ; they were of admirable transparency, the base exhibiting 
 blood-red, and the green of the middle being that of the pale 
 emerald ; the brightness would diminish, the colours disappear, 
 and all be extinguished, sometimes suddenly, and sometimes by 
 slow degrees. After this disappearance, fragments of the bow 
 would be reproduced, would continue their upward movement, 
 and approach the zenith ; the rays, by the effect of perspective,, 
 would be gradually shortened ; the thickness of the arc, which 
 presented then the appearance of a large zone of parallel rays, 
 would be estimated ; then the vertex of the bow would reach the 
 magnetic zenith, or the point to which the south pole of the 
 dipping needle is directed. At that moment the rays would be 
 seen in the direction of their feet. If they were coloured, they 
 would appear as a large red band, through which the green tints 
 of their superior parts could be distinguished ; and if the wave of 
 light above mentioned passed along them, their feet would form a 
 a long sinuous undulating zone ; while, throughout all these 
 changes, the rays would never suffer any oscillation in the direc- 
 tion of their axis, and would constantly preserve their mutual 
 parallelisms. 
 
 While these appearances are manifested, new bows are formed, 
 either commencing in the same diffuse manner, or with vivid and 
 ready-formed rays : they succeed each other, passing through 
 nearly the same phases, and arrange themselves at certain, 
 distances from each other. As many as nine have been counted, 
 having their ends supported on the earth, and, in their arrange- 
 ment, resembling the short curtains suspended one behind the 
 other over the scene of a theatre, and intended to represent the 
 sky. Sometimes the intervals between these bows diminish, and 
 two or more of them close upon each other, forming one large zone^ 
 190 
 
AUKOEA BOREALIS. 
 
 traversing tlie heavens, and disappearing towards the sonth^ 
 becoming rapidly feeble after passing the zenith. But sometimes,, 
 also, when this zone extends over the summit of the firmament 
 from east to west, the mass of rays appears suddenly to come from 
 the south, and to form with those from the north the real boreal 
 corona, all the rays of which converge to the zenith. This 
 appearance of a crown, therefore, is doubtless the mere effect of 
 perspective ; and an observer, placed at the same instant at a 
 certain distance to the north or to the south, would perceive only 
 an arc. 
 
 The total zone, measuring less in the direction north and south 
 than in the direction east and west, since it often leans upon the 
 earth, the corona would be expected to have an elliptical form ;. 
 but that does not always happen : it has been seen circular, the 
 unequal rays not extending to a greater distance than from eight 
 to twelve degrees from the zenith, while at other times they reach 
 the horizon. 
 
 Let it, then, be imagined, that all these vivid rays of light 
 issue forth with splendour, subject to continual and sudden- 
 variations in their length and brightness; that these beautiful 
 red and green tints colour them at intervals ; that waves of light 
 undulate over them ; that currents of light succeed each other ; 
 and, in fine, that the vast firmament presents one immense and 
 magnificent dome of light, reposing on the snow-covered base 
 supplied by the ground — which Jtself serves as a dazzling frame 
 for a sea, calm and black as a pitchy lake — and some idea, though 
 an imperfect one, may be obtained of the splendid spectacle which 
 presents itself to him who witnesses the aurora from the Bay 
 of Alten. 
 
 The corona, when it is formed, only lasts for some minutes : 
 it sometimes forms suddenly, without any previous bow. There- 
 are rarely more than two on the same night ; and many of the 
 auroras are attended with no crown at all. 
 
 The corona becomes gradually faint, the whole phenomenon 
 being to the south of the zenith, forming bows gradually paler, 
 and generally disappearing before they reach the southern 
 horizon. All this most commonly takes place in the first half- of 
 the night, after which the aurora appears to have lost its intensity : 
 the pencils of rays, the bands, and the fragments of bows appear 
 and disappear at intervals ; then the rays become more and more 
 diffused, and ultimately merge into the vague and feeble light 
 which is spread over the heavens, grouped like little clouds, and 
 designated by the name of auroral plates [plaques aurorales). 
 Their milky light frequently undergoes strildng changes in its 
 brightness, like motions of dilatation and contraction, which are 
 
 191 
 
THUNDER AND LIGHTNING. 
 
 propagated reciprocally between the centre and the circumference, 
 like those which are observed in marine animals called Medusse. 
 The phenomena become gradually more faint, and generally 
 disappear altogether on the appearance of twilight. Sometimes, 
 however, the aurora continues after the commencement of day- 
 break, when the light is so strong that a printed book may be 
 read. It then disappears, sometimes suddenly ; but it often 
 happens that, as the daylight augments, the aurora becomes 
 gradually vague and undefined, takes a whitish colour, and is 
 ultimately so mingled with the cirrho- stratus clouds, that it is 
 impossible to distinguish it from them. 
 
 Some of the appearances here described are represented in figs. 
 4, 5, 6, 7, copied from the memoir of M. Lottin. 
 
 Fig. 6. 
 
 Fig. 7. 
 
 The height of the auroras has not certainly been ascertained; 
 "but as they are atmospheric phenomena, and scarcely above the 
 region of the clouds, and as they certainly partake of the diurnal 
 motion of the earth, it does not seem probable that their elevation 
 in any case can exceed a few miles. 
 
 192 
 
ELECTRO-MOTIVE POWER. 
 
 'CHAPTER I. 
 
 1, Prospects of improvement in motiye power by the application of 
 electricity. — 2. Example of its practical application in the workshop 
 of Mons. Froment, mathematical instrument maker in Paris. — o. 
 Mention of it in Catalogue of the Great Exhibition in Hyde Park. 
 — 4. Property of electro-magnets. — 5. Alternate transmission and 
 suspension of the current. — 6. How this produces a moving power. 
 — 7. Voltaic piles used by Mons. Froment. — 8. Forms of his electro- 
 
 Labdnek's Museum of Sciencs. o 193 
 
 ISO. 124. 
 
ELECTRO-MOTIVE POWER. 
 
 motive macliines. — 9. Details of their construction. — 10. Regulator 
 applied to them. — 11. Their application to divide the limbs of philo- 
 sophical instruments. — 12. Their wonderful self-acting power. — 13. 
 Application of electro-motive power to the telegraph by Mons. 
 Froment. — 14. Microscopic writing. — 15. Electric clocks. 
 
 1. Among those who have devoted their thoughts to the applica- 
 tion of the principles of physical science to the industrial arts, an 
 anticipation more or less sanguine has long been entertained that 
 the day is not far distant when the mighty power of steam, which 
 has exercised, and still continues to exercise, so great an influ- 
 ence upon the well-being of the human race and the progress of 
 civilisation, will be superseded by other far more efficient 
 mechanical agents. Science already directs her finger at sources 
 of inexhaustible power in the phenomena of electricity and mag- 
 netism. The alternate decomposition and recomposition of water, 
 by electric action, has too close an analogy to the alternate pro- 
 cesses of vaporisation and condensation, not to occur at once to 
 every mind : the development of the gases from solid matter by 
 the operation of the chemical affinities, and their subsequent 
 condensation into the liquid form, has already been essayed as a 
 source of power. In a word, the general state of physical science 
 at the present moment, the vigour, activity, and sagacity with 
 which researches in it are prosecuted in every civilised country, 
 the increasing consideration in which scientific men are held, and 
 the personal honours and rewards which begin to be conferred 
 upon them, all justify the expectation that we are on the eve of 
 mechanical discoveries still greater than any which have yet 
 appeared ; that the steam engine itself, with its gigantic powers, 
 will dwindle into insignificance in comparison with the energies 
 of nature which are still to be revealed ; and that the day will 
 come when that machine, which is now extending the blessings 
 of civilisation to the most remote skirts of the globe, will cease to 
 have existence except in the page of history. 
 
 2. It is not, however, generally known, that there exists in Paris 
 an establishment for the fabrication of philosophical instruments, 
 or rather of that class of those instruments which in that country 
 are distinguished as instruments of precision, in which elec- 
 tro-magnetism is and has been for several years back applied 
 with complete success, as a moving power on a considerable 
 scale. 
 
 3. In the Crystal Palace in Hyde Park, a small modest-looking 
 stall furnished with theodolites and some models of electro- 
 magnetic apparatus might have been seen, bearing the inscription 
 of Gustavo Froment ; and in the Great Illustrated and com- 
 mentated Catalogue there appeared the three following lines : — 
 
 104 
 
GUSTAVE FEOMENT. 
 
 " GusTAVE Froment — 5 rue Menilmontant, Paris. 
 Scientific Instruments. Theodolite ; and various models of 
 €lectro-motive power." 
 
 Assuredly brevity could no further go. ITever was presented 
 a more conspicuous example of modest reserve on the part of 
 artistic genius the most exalted. No effort seems to have been 
 thought of by the exhibitor, even to call the attention of the com- 
 mentators of the catalogue, to the claims of these productions of 
 the highest scientific art ; for, while comment and panegyric have 
 been liberally, not to say profusely, accorded to exhibitors, who, 
 whatever may have been their merits, presented claims immea- 
 surably below him whose illustrious labours we are about to 
 notice, not a single word of comment drew the attention of the 
 general public to objects, the fabrication of which would have 
 presented the highest attractions, even to the most idle and 
 incurious of the loungers of the Crystal Palace, 
 
 Happily for the cause of science and art, and for that of justice, 
 the same neglect did not prevail among the eminent persons to 
 whom the distribution of honours was entrusted. They discerned 
 and appreciated the titles of M. Froment, and most justly accorded 
 him, by an unanimous vote, a council medal. The authorities of 
 his own country added to this the decoration of the Legion of 
 Honour. 
 
 If M. Froment were as ambitious of personal eclat as of the 
 attainment of perfection in his workmanship, he would have trans- 
 ported to the Crystal Palace a part of the beautiful machinery of 
 his Parisian workshop, and would have exhibited, not his theodolite 
 alone, but the process of its fabrication. Had he done this (and 
 he might have accomplished it without difficulty), his station in 
 the Grreat Exhibition as an object of attraction would have 
 rivalled even the Koh-i-noor. 
 
 The inventions and improvements of M. Froment, in the con- 
 struction of instruments of precision, and of scientific apparatus 
 • generally, can nowhere be so advantageously seen and appreciated 
 as in his own workshop in Paris. There may be seen not only the 
 finished instruments and machines, but their practical application 
 in the construction of each other J There may be seen electro- 
 magnetism applied on a large scale, as a permanent and regular 
 moving power, in the fabrication of mathematical and optical 
 instruments. 
 
 The electro-motive machines of M. Froment, which are very 
 various in form, magnitude, and power, derive, nevertheless, their 
 motive force from one common principle, which is the same that 
 has been applied in certain forms of electro-magnetic telegraph. 
 
 4. The property of the electro-magnet has been already so fully 
 0 2 195 
 
ELECTiiO-MOTlVE POWEli. 
 
 explained in our Tract upon tlie ''Electric Telegraph," page 196, 
 that it will be sufficient briefly to recapitulate the general physical 
 principles from which this property arises. 
 
 If a voltaic current be conducted spirally round a rod of soft 
 iron, the iron will become magnetic, and will continue magnetic 
 so long as the current passes round it. Its acquisition of the 
 magnetic virtue is simultaneous with the transmission of the 
 current. It is not gradual but instantaneous. The very instant 
 the current is transmitted, the magnetic virtue is imparted to the 
 iron, and does not afterwards increase in intensity. 
 
 The loss of the magnetic virtue, upon the suspension of the 
 current, is equally instantaneous and complete. The very instant 
 the current is discontinued, the iron ceases to be magnetic. 
 
 The subtlety of the electric fluid, and the celerity of its pro- 
 pagation, are such that it is capable of being transmitted and 
 suspended instantaneously, and, however short the interval may 
 be between the instants of its transmission and suspension, it will, 
 during that interval nevertheless, impart to the iron the magnetic 
 property. So true is this, that it is practically found that the 
 current may be alternately transmitted and suspended hundreds 
 or even thousands of time in a single second, and in these short 
 intervals the iron will alternately acquire and lose the. magnetic 
 virtue. 
 
 The manner in which the voltaic current is transmitted spirally 
 round the iron bar is as follows : — The wire upon which the current 
 J is transmitted is wrapped with silk or 
 
 J cotton thread, which being a non-con- 
 ductor of electricity, will prevent the 
 lateral escape of the fluid, which will 
 therefore pass along the wire within the 
 coating of thread as water or air would 
 pass along a tube. The wire thus covered 
 ;$v is coiled spirally round the bar of soft 
 iron, which may or may not be bent into 
 the horse-shoe form, as shown in fig. 1. 
 One end of the wire being put in connection 
 with the positive, and the other with the negative pole of the voltaic 
 battery ; the current will be transmitted upon it, and will be pre- 
 vented from passing from one coil of the wire to the contiguous 
 one, by the interposition of the silk or cotton thread. So long as 
 the current is thus continued, the iron, whatever be its form, will 
 be magnetic, one end having the properties of the north and the 
 other of the south magnetic pole. 
 
 5. By an expedient to which an infinite variety of forms may 
 be given, the current can be alternately transmitted and suspended 
 196 
 
THE ELECTKO-MAGNET. 
 
 with any desired degree of rapidity; and, by varying the power of 
 the battery, the number of coils of the spiral wire, and the mag- 
 nitude of the iron bar, a magnetic force of any desired intensity 
 can be produced. 
 
 A piece of iron, called an armature, is presented to one or both 
 of the poles of the magnet towards which it is attracted, while the 
 current is transmitted with a force proportionate to the intensity of 
 the magnetism ; and when the current is suspended, the armature 
 either falls from the magnet by its own weight, or is withdrawn 
 from it by the action of a spring, or other mechanical expedient, 
 provided for the purpose. 
 
 The armature may be placed between two magnets, which are 
 alternately acted upon by the electric current, which is trans- 
 mitted round each in the intervals of its suspension round the 
 other. The armature will then be moved alternately to and fro 
 between the two magnets. 
 
 6. In this manner, by alternately suspending and transmitting 
 the current on the wire which is coiled round the electro-magnet, 
 the magnet and its armature receive an alternate motion to and 
 from each other, similar to that of the piston of a steam-engine, 
 or the foot of a person who works the treddle of a lathe. This 
 alternate motion is made to produce one of continued rotation by 
 the same mechanical expedients as are used in the application of 
 any other moving power. 
 
 The force with which the electro -magnet and its armature 
 attract each other, determines the power of the electro -motive 
 machine, just as the pressure of steam on the piston determines 
 the power of a steam-engine. This force depends on the nature 
 and magnitude of the galvanic pile which is employed. 
 
 7. The pile used by M. Froment for the lighter sort of work, 
 such as that of driving his engines for dividing the limbs of 
 astronomical and surveying instruments, and microscopic scales, 
 is that of Daniel, consisting of about twenty-four pairs. Simple 
 arrangements are made by means of commutators, reometers, and 
 reotropes, for modifying the current indefinitely in quantity, 
 intensity, and direction. By merely turning an index or lever in 
 one direction or another, any desired number of pairs may bo 
 brought into operation, so that a battery of greater or less inten- 
 sity may be instantly made to act, subject to the major limit of 
 the number of pairs provided. By another adjustment, the copper 
 elements of two or more pairs, and at the same time their zinc 
 elements, may be thrown into connection, and thus the whole pile, 
 or any portion of it, may be made to act as a single pair, of 
 enlarged surface. By another adjustment, the direction of the 
 current can be reversed at pleasure. Other adjustments, equally 
 
 197 
 
ELECTRO-MOTIVE POWEK. 
 
 simple and effective, are provided, by which, the current can be 
 turned on any particular machine, or directed into any room in 
 which it may be required. 
 
 The pile used for heavier work, is a modification of Bunsen's 
 charcoal battery, in which dilute sulphuric acid is used in the 
 porous porcelain cell containing the charcoal, as well as in the cell 
 containing the zinc. By this expedient the noxious fumes of the 
 nitric acid are removed, and although the strength of the battery 
 is diminished, sufficient power remains for the purposes to which 
 it is applied. 
 
 8. The forms of electro-motive machines constructed by M. 
 Froment are very various. In some the magnet is fixed, and the 
 armature moveable ; in some both are moveable. 
 
 In some there is a single magnet and a single armature. The 
 power is in this case intermittent, like that of a single-acting 
 steam-engine, or that of the foot in working the treddle of a lathe, 
 and the continuance of the action is maintained in the same manner 
 by the inertia of a fiy-wheel. 
 
 In other cases two electro-magnets and two armatures are com- 
 bined, and the current is so regulated, that it is established on 
 each during the intervals of its suspension on the other. This 
 machine is analogous in its operation to the double-acting steam- 
 engine, the operation of the power being continuous. The force 
 of these machines may be augmented indefinitely, by combining 
 the action of two or more pairs of magnets. 
 
 Another variety of the application of this moving principle, 
 presents an analogy to the rotatory steam-engine. Electro- 
 magnets are fixed at equal distances round a wheel, to the 
 circumference of which the armatures are attached at corre- 
 sponding intervals. In this case the intervals of action and 
 intermission of the currents are so regulated, that the magneto 
 attract the armatures obKquely as the latter approach them, the 
 current, and consequently the attraction, being suspended the 
 moment contact takes place. The effect of this is, that all the 
 magnets exercise forces which tend to turn the wheel on which 
 the armatures are fixed constantly in the same direction, and the 
 force with which it is turned is equal to the sum of the forces of 
 all the electro-magnets which act simultaneously. 
 
 This rotatory electro-motive machine is infinitely varied, not 
 only in its magnitude and proportions, but in its form. Thus in 
 some the axle is horizontal, and the wheel revolves in a vertical 
 plane ; in others the axle is vertical, and the wheel revolves in a 
 horizontal plane. In some the electro-magnets are fixed, and the 
 armatures moveable with the wheel ; in others both are moveable. 
 In some the axle of the wheel which carries the armatures is itself 
 198 
 
ELECTEO-MOTIVE MACHINES. 
 
 moveable, being fixed upon a crank or eccentric. In this case the 
 wheel revolves within another, whose diameter exceeds its own 
 by twice the length of the crank, and within this circle it has an 
 hypocycloidal motion. 
 
 Each of these varieties of the application of this power, as yet 
 novel in the practical operations of the engineer and manufacturer, 
 possesses peculiar advantages or convenience, which render it more 
 eligible for special purposes. 
 
 9. Electro-motive machines. — To render this general descrip- 
 tion of M. Troment's electro-motive machines more clearly under- 
 stood, we shall add a detailed explanation of two of the most 
 efficient and useful of them. 
 
 In the machine represented in fig. 2, a and h are the two legs 
 of the electro-magnet ; c is the transverse piece uniting them, 
 which replaces the bend of the horse-shoe; ef is the armature 
 confined by two pins on the summit of the leg a (which prevent 
 any lateral deviation), the end / being jointed to the lever g A, 
 which is connected with a short arm projecting from an axis h by 
 the rod ^. "When the current passes round the electro-magnet, 
 the lever / is drawn down by the attraction of the leg h, and 
 draws with it the lever g h, by which i and the short lever pro- 
 jecting from the axis k are also driven down. Attached to the 
 same axis is a longer arm m, which acts by a connecting rod n 
 upon a crank o and a fly-wheel v. "When the machine is in 
 motion, the lever g h and the armature / attached to it recover 
 their position by the momentum of the fly-wheel, after having 
 been attracted downwards. "When 'the current is again esta- 
 blished, the armature / and the lever g h are again attracted 
 downwards, and the same eflects ensue. Thus, during each half- 
 revolution of the crank o, it is driven by the force of the electro- 
 magnet acting on /, and during the other half-revolution it is 
 carried round by the momentum of the fly-wheel. The current 
 is suspended at the moment the crank o arrives at the lowest 
 point of its play, and is re-established when it returns to the 
 highest point. The crank is therefore impelled by the force of 
 the magnet in the descending half of its revolu- 
 tion, and by the momentum of the fly-wheel in the 
 ascending half. 
 
 The contrivance called a distributor, by which the 
 current is alternately established and suspended at 
 the proper moments, is represented in fig. 3, where 
 y represents the transverse section of the axis of 
 the fly-wheel ; r, a spring which is kept in con- 
 stant contact with it; x, an eccentric fixed on the same axis 
 y, and revolving with it and r' another spring similar to r, 
 
 199 
 
ELECTRO-MOTIVE POWEll. 
 
 Avliicli is acted upon by the eccentric, and is thus allowed to 
 jiress against the axis y during half the revolution, and removed 
 from contact with it during the other half-revolution. When 
 the spring r' presses on the axis y the current is established ; 
 and when it is removed from it the current is suspended. 
 
 It is evident that the action of this machine upon the lever 
 attached to the axis k is exactly similar to that of the foot on the 
 treddle of a lathe or a spinning-wheel ; and as in these cases, thf 
 impelling force being intermittent, the action is unequal, the 
 velocity being greater during the descending motion of the crank o 
 than during its ascending motion. Although the inertia of the 
 tiy- wheel diminishes this inequality by absorbing a part of the 
 moving power in the descending motion, and restoring it to the 
 crank in the ascending motion, it cannot altogether efface it. 
 
 Another electro-motive machine of M. Froment is represented 
 in elevation in fig. 4, and in plan in fig. 5. This machine has the 
 
 Fig. 4. 
 
 advantage of producing a perfectly regular motion of rotation, 
 v/hich it retains for several hours without sensible change. 
 
 A drum, which revolves on a vertical axis x y, carries on its 
 circumference eight bars of soft iron a placed at equal distances 
 asunder. These bars are attracted laterally, and always in the 
 same direction, by the intermitting action of six electro-magnets 
 6, mounted in a strong hexagonal frame of cast-iron, within 
 which the drum revolves. The intervals of action and suspension 
 200 
 
DETAILS OF COITSTRUCTIOIT. 
 
 of tlie current upon these magnets are so regulated that it is 
 established upon each of them at the moment one of the bars , of 
 
 Fig. 5. 
 
 soft iron a is approaching it, and it is suspended at the moment 
 the bar begins to depart from it. Thus the attraction accelerates 
 the motion of the drum upon the approach of the piece a towards 
 the magnet 5, and ceases to act when the piece a arrives in front 
 of h. The action of each of the six impelling forces upon each of the 
 eight bars of soft iron attached to the drum is thus intermitting. 
 During each revolution of the drum, each of the eight bars a 
 receives six impulses, and therefore the drum itself receives forty- 
 eight impulses. If we suppose the drum to make one revolution 
 in four seconds, it will therefore receive a succession of impulses 
 at intervals of the twelfth part of a second, which is prac- 
 tically equivalent to a continuous force. 
 
 The intervals of intermission of the current are regulated by 
 a simple and ingenious apparatus. A metallic disc c is fixed upon 
 the axis of rotation. Its surface consists of sixteen equal divisions, 
 the alternate divisions being coated with non-conducting matter, 
 A metallic roller A, which carries the current, presses constantly 
 on the surface of this disc, to which it imparts the current. Three 
 other metallic rollers e, /, g press against the edge of the disc, and, 
 as the disc revolves, come alternately into contact with the con- 
 ducting and non-conducting divisions of it. When they touch 
 
 *201 
 
ELECTRO-MOTIVE POWER. 
 
 the conducting divisions, the current is transmitted ; when they 
 touch the non-conducting divisions, the current is interrupted. 
 
 Each of these three rollers e, /, g is connected by a conducting 
 wire with the conducting wires of two electro-magnets diame- 
 trically opposed, as is indicated in fig. 5, so that the current is 
 thus alternately established and suspended on the several electro- 
 magnets, as the conducting and non-conducting divisions of the 
 disc pass the rollers e, /, and g, 
 
 10. M. Froment has adapted a regulator to this machine, which 
 plays the part of the governor of the steam-engine, moderating 
 the force when the action of the pile becomes too strong, and 
 augmenting it when it becomes too feeble. 
 
 A divided circle m n, fig. 4, has been annexed to the machine 
 at the suggestion of M. Pouillet, by which various important 
 physical experiments may be performed. 
 
 11. Of all the purposes to which this moving power is applied 
 in the workshop of M. Froment, the most beautiful is that of 
 making the divisions on the limbs and scales of astronomical and 
 geodesical instruments, and of instruments of precision in general. 
 The machines by which such divisions are engraved are automatic, 
 each receiving its motion from an electro-motive machine of 
 proportionate power and magnitude. 
 
 The limb to be' divided is fixed upon a horizontal table, which 
 receives a slow and intermitting progressive motion from a fine 
 screw. This screw itself is urged at intervals by a ratchet-wheel. 
 The catch or click by which this ratchet-wheel is driven, can be 
 so adjusted as to take one, two, or several teeth at each stroke, 
 and therefore to move the table carrying the limb through a 
 greater or less space, according to the magnitude of the divisions 
 to be engraved upon the scale. Over the limb to be engraved is 
 placed the point or edge by which the incision is produced, which 
 is either hardened steel or diamond. During the progressive 
 motion of the table carrying the limb, this cutter is elevated, so as 
 not to touch it. In the intervals during which the motion of the 
 table is suspended, the cutter descends upon the limb, and, being 
 pressed upon it with sufficient force, is drawn upon it in a 
 direction at right angles to the motion of the table, thus engraving 
 upon it the line which marks the division. Thus the motions of 
 the limb and the cutter are alternate, each being in action while 
 the other is at rest. The cutter is fixed upon an arbor which 
 derives its motion from the same crank which works the ratchet, 
 but its connection is arranged so as to give them the alternate 
 action just mentioned. 
 
 By an arrangement provided in this arbor, a more extended 
 motion is imparted to the cutter at every tenth stroke of the 
 202 
 
DiyiDING MACHINES. 
 
 ratchet, the effect of which is, that every tenth division made 
 upon the limb by the cutter is distinguished by a longer line than 
 the intermediate divisions. 
 
 In some cases both the motions above described are imparted to 
 the cutter, the limb upon which the divisions are engraved being 
 kept at rest. The cutter is, in that case, alternately impressed 
 with two motions, one which transfers it from division to division 
 while it is raised from the limb, and the other in a direction at 
 right angles to this, while it is pressed upon the limb, and makes 
 the incision which marks the division. 
 
 These dividing instruments vary in form and magnitude accord- 
 ing to the purposes to which they are applied. 
 
 Those which are used for engraving the divisions on the circular 
 limbs of theodolites and other instruments of the larger class, 
 consist of a circular metallic table of solid construction and suit- 
 able magnitude, to which a motion round its centre in , its own 
 plane is imparted by means of a finely-constructed worm, which 
 works in teeth formed on the edge of the circular table itself. 
 Means are provided by which the circular limb to be divided can 
 be fixed upon this table, so as to be exactly concentric with it, 
 and to be moved with it. The cutter is fixed so as to slide upon 
 a rod which is extended over this table and parallel to it. The 
 cutter can, by this arrangement, be adjusted at any required dis- 
 tance from the centre of the table, so as to correspond to a circular 
 limb of any magnitude not exceeding that of the table. 
 
 In the process of engraving the divisions, the worm and the 
 cutter are moved alternately by self-acting mechanism, deriving 
 its motion from the electro-motive machine by which all the 
 apparatus of the workshop is driven. The worm is so adjusted, 
 that by each action on the table, the limb to be engraved is 
 moved under the cutter (which is then elevated so as not to act 
 upon it), through a space equal to the interval between the 
 divisions. The worm then stops, and the limb being at rest, the 
 cutter descends upon it, and is drawn through a space equal to 
 the length of the line to be engraved, and the division is accord- 
 ingly marked upon the limb. The cutter is then again elevated, 
 and the limb again moved under it by the worm, and so on. 
 
 In this case the divisions which mark degrees are distinguished 
 from the intermediate minutes by larger lines, mechanical arrange- 
 ments being provided in the wheelwork by which the motion of 
 the cutter is thus affected. 
 
 12. All these machines are self-acting. The limb or scale to be 
 divided being once placed on the table of the dividing engine, no 
 further interference of the human hand is needed. The machine 
 of itself begins its work at an appointed hour, minute, and 
 
 203 
 
ELECTRO-MOTIVE POWER. 
 
 second, and when the last division of the scale has been engraved, 
 it not only suspends its own action, but stops that of the electro- 
 magnetic machine by which it is impelled. These automatic 
 arrangements must not be regarded as mere mechanical super- 
 fluities, upon which the boundless fertility of invention which 
 characterises the genius of M. Froment has been lavished ; they 
 are of great practical value and. importance. It happens, for 
 example, that in these delicate operations, the tremor of the 
 ground on which the workshop stands, produced by the movement 
 of vehicles of transport in the adjoining streets, affects in a 
 sensible degree the motion of the cutting point. It is therefore 
 always preferable to execute the most delicate work in the dead 
 of the night. Now, by the automatic contrivances above men- 
 tioned, this can be accomplished without imposing on the super- 
 intendent the necessity of watching. A clock, provided with an 
 apparatus similar in principle to a common alarum, is put in 
 mechanical connection with the dividing machine, and is set so as 
 to start the machine at any desired hour. This being done, and 
 the limb to be divided being fixed upon the table under the 
 cutter, the apparatus maybe left to itself; the superintendent 
 may retire to rest, and at the hour of the night which has been 
 selected, the electro-motive machine will be started by the clock, 
 and the dividing engine will commence, continue, and complete 
 its work with the most admirable certainty and precision, and, 
 when completed, the electro-motive machine will be stopped, and 
 all reduced to rest. 
 
 The magnitude of the dividing engine for microscopic scales, is 
 about 8 inches long by 6 inches wide, and 4 inches high. The 
 magnitude of the electro-motive engine necessary to drive it, 
 is not more than 4 inches square in its base, and 3 inches 
 high. 
 
 It is scarcely necessary to observe, that the more minute class 
 of these scales can only be seen by the aid of a microscope of high 
 magnifying power. This will be easily understood when it is 
 considered that, in a space measuring a tenth of an inch in 
 length, there are in the more minute scales, 2500 divisions. Such 
 is, nevertheless, the precision of the execution, that when looked 
 at with a sufficiently high magnifying power, the lines exhibit the 
 most perfect evenness and regularity. 
 
 13. Among the inventions of M. Froment, which may be also 
 seen in operation in his establishment, are two electric telegraphs, 
 one of which transmits its messages by enabling an operator at 
 one station to direct an index, which moves upon a dial-plate, to 
 any desired letter of the alphabet, those letters being engraved 
 around the dial like the hour-mark upon a clock or watch. The 
 204 
 
TELEGEAPHIC INSTEUMENTS. 
 
 transmitting agent lias before him a row of keys, like those of a-, 
 piano-forte (fig. 6), upon which the letters of the alphabet are 
 
 Fig. 6. — Froment's Alpliabctical Telegraph. 
 
 engraved. When he presses down the key upon which any letter- 
 is inscribed, the index of the dial at the distant station with 
 which he is in communication turns, and stops when it points at 
 the same letter. In this way, by indicating the successive letters 
 of the words composing the message, the despatch is transmitted. 
 
 The mechanism by which this is accomplished, is fully described 
 in our Tract on the " Electric Telegraph," pa,r. 205. 
 
 Another form of electric telegraph (fig. 7), which writes the 
 message it transmits, may also be seen in operation in M. Froment's 
 workshop. 
 
 The message is transmitted in this instrument by pressing 
 down a key successively by the finger, the key being^^held down a* 
 longer or shorter time, in the same manner as a pianist would 
 play notes of greater or less length. Yarying marks of corre- 
 sponding lengths are made upon paper by a pencil at the distant 
 station, the paper being moved under the pencil by suitable 
 mechanism. For a description of this telegraph see also our 
 Tract on the ''Electric Telegraph," par. 207. 
 
 14. Another of the results of the mechanical ingenuity of this- 
 artist, which may be seen at his workshop, which if not the most 
 useful is assuredly the most astonishing, and to many the most. 
 
 205 
 
ELECTRO-MOTIVE POWER. 
 
 incomprelieiisible, is his microscopic writing-, which has been 
 already noticed in our Tract on Microscopic Drawing and 
 
 Fig. 7.— Froment's Writing Telegraph. 
 
 Engraving. "We will here reproduce from that article a specimen 
 of this miraculous performance. Fig. 8, written in the Crystal 
 Palace, in 1851, within a circular space, having the diameter 
 of the 30th of an inch. 
 
 The details of the method by which this microscopic writing is 
 executed have not yet been made public, but we believe the 
 inventor is preparing a memoir on the subject, to be presented to 
 the Academy of Sciences. 
 
 15. This brief notice of the application of electro-motive power 
 must not be concluded without mentioning its remarkable appli - 
 cation to chronometers, examples of which may be seen in many 
 parts of this country, one of which is presented daily and nightly 
 in the Strand, near the Electric Telegraph Office. 
 
 The general principle of this beautiful application of physical 
 science to the economy of life is easily explained, 
 
 The hand of a clock or watch moves not uniformly, but by a 
 succession of starts, as may be plainly seen in the case of a 
 seconds' hand of a watch or clock. The same intermitting motion 
 aifects the minute and hour hands, but their movement from 
 second to second is so minute that it is imperceptible to the eye. 
 
 Now, from what has been already explained, it will be evident 
 that a similar intermitting motion can be imparted to the contact 
 piece of an electro-magnet by the alternate transmission and 
 suspension of the current. If, therefore, by any means the electric 
 206 
 
MICEOSCOPIC WEITING. 
 
 current can be transmitted and suspended alternately with chro- 
 nometric regularity, so that, for example, the interval of its 
 
 Fig. 8. — Appearance as seen in the field of the Microscope the outer circle being only 
 l-30th of an inch in diameter. 
 
 transmission and suspension shall be exactly one second of time, 
 then the motion to and fro of the contact piece will also be per- 
 formed with the same chronometric regularity, in intervals of one 
 second. It is evident, therefore, that if such a contact piece, so 
 moving, be put in connection with a properly constructed frame of 
 wheel- work, it may be used to impart motion to the hands of a 
 timepiece. 
 
 It appears also that the same regularly intermitting current 
 may be transmitted to any number of timepieces, at any distance 
 whatever from each other, by means of conducting wires similar 
 to those of the electric telegraph ; and since the length of such 
 intermediate wires does not affect their power of transmission, it 
 
 207 
 
ELECTRO-MOTIVE POWEli. 
 
 follows that the same current can simultaneously impart a perfectly 
 regular chronometric motion, to all the clocks dispersed oyer a 
 large countiy. 
 
 It remains only to show how the regularity of the intermission 
 of the current can be obtained. This is accomplished by the 
 obvious expedient of putting the commutator, by the motion of 
 which the current is alternately transmitted and interrupted, in 
 connection with a well-regulated chronometer, the pendulum of 
 which shall, in that case, itself alternately transmit and suspend 
 the current. 
 
 Among the numerous applications of electric power to be seen 
 in the workshops of M. Froment, are a series of electric clocks 
 constructed nearly upon the principle above described. The 
 motion of each clock is in this case maintained by a small weight, 
 which is alternately raised and lowered upon an appendage of the 
 pendulum by means of an iron counterweight, which is itself 
 alternately raised and disengaged by an electro-magnet, each 
 time that the appendage, by its contact with the weight, opens and 
 closes the voltaic circuit, or, what is the same, transmits and 
 suspends the current. 
 
 The motion of the clock is maintained by a constant weight, 
 without friction and without the application of oil, with great 
 regularity, while the electric current, which is transmitted 
 through it in the intervals of each oscillation, transmits to a 
 distance the chronological indications upon a series of dials, the 
 hands of which are moved by a mechanism, analogous to that 
 which moves the index of an electric telegraph of the kind used 
 on the continental railways. 
 
INDEX TO VOLUMES IX. AND X. 
 
 Aberration of lenses, ix. 9. 
 
 AebrOinatic object lenses, ix. 9. 
 
 Admiralty steam experiments, x. 165. 
 
 Africa, ix. 155 ; its climatological 
 zones, ix. 142 ; the Tell and the 
 Sahara, ix. 143. 
 
 Air and earth, effects of their con- 
 tact, ix. 183. 
 
 Alecto steamer, experiments on, x. 
 163. 
 
 AUeghanies, ix. 153. 
 Alps, ix. 187. 
 
 Amazons, ix. 162 ; tributaries of, ix. 
 163. 
 
 Andes of Patagonia, Chili, ix. 152 ; 
 
 of Bolivia and Peru, ib. ; vege- 
 tation of, ix. 179-80. 
 Angular aperture of lens, effects of, 
 
 capable, greatest of which a lens is 
 
 ix. 11 ; ix. 13. 
 Angular magnitude, visual estimate 
 
 of, ix. 61. 
 Ant, error in Prior's allusion to its 
 
 foresight, ix. 205 ; allusions to in 
 
 the Proverbs, ix. 206. 
 Antarctic drift current, its equatorial 
 
 course, ix. 190-1. 
 Antennae, their use, x. 90. 
 Anthidium manicatum, x. 19-20. 
 Apiarian researches, antiquity of, 
 
 X. 2. 
 
 Agriculture, x. 97. 
 Archipelago, ix. 141. 
 Arctic circles and frigid zones, ix. 
 173. 
 
 Aristomachus, x. 3. 
 Aristotle, x. 3. 
 
 Arrogant steamer, engines of, x. 169. 
 Artificial light, ix. 46. 
 Asia, its plateaux, its physical cha- 
 racter, ix. 146-7. 
 
 Atlantic steamers, x. 116; steam na- 
 vigation, its history, x. 117. 
 
 Atmospheric electricity x. 177. 
 
 Aurora borealis, x. 187-9. 
 
 Australia, its territory and physical 
 features, its climate, vegetable pro- 
 ductions, indigenous animals, mine- 
 rals, gold, aboriginal tribes, ix. 
 148-9. 
 
 Auxiliary steam power, x. 121. 
 Azoff, sea of, ix. 142. 
 
 Basin of water, experiments with, 
 ix. 196. 
 
 Bee, its senses, x. 87 ; its memory, x. 
 88 ; their wars and battles, x. Ill ; 
 their number of daily excursions, 
 X. 82 ; their pasturage, x. 83 ; 
 their fidelity to their queen, x. 68 ; 
 their policy, x. 64 ; their transfor- 
 mations, X. 49 : their magnitude 
 and weight, x. 57 ; their maladies, 
 X. 108 ; their neatness, x. 83 ; 
 expedient for keeping their nests 
 warm, x. 20 ; their enemies, x. 
 84 ; their means of defence, x. 
 85 ; their personal antipathies, x. 
 90 ; pap for their young, x. 42-3 ; 
 food adapted to age, x. 43 ; trans- 
 formation, X. 43-4 ; remarkable 
 care of the nurses, x. 46 ; cross 
 alleys connecting their streets, x. 
 47 ; first laying of the queen in 
 spring, ib. ; queen's royal suite, 
 X. 48 ; queen's eggs, ib. ; cor- 
 rection of their mistakes in work- 
 ing, X. 37 ; dimensions of their 
 first wall, ib. ; operations of 
 the nurses, ib. ; bases of their 
 cells, X. 38 ; their completion of 
 pyramid at loases, ib. ; pyrami- 
 1 
 
INDEX TO VOLUMES IX. AND X. 
 
 dal partitions in their cells, ih. ; 
 the foimatiou of their cells, x. 39 ; 
 arrangement of combs, ib. ; sides 
 cf the same not parallel, x. 39-40 ; 
 labour of, successive, x, 41 ; di- 
 mensions of their cells, ib. ; 
 number of the same, x, 42 ; bread, 
 ib. ; its sting, x. 14 ; its organs 
 of fecundation and reproduction, 
 ib. ; number of eggs produced 
 by the queen, x. 16 ; test of its 
 social condition, x. 18 ; individual 
 and collective habits, x. 19 ; soli- 
 tary, ib. ; structure of their 
 nests, X. 29 ; situation of the same, 
 X. 19 ; its structure and members, 
 X. 10 ; use of its proboscis, ib. ; 
 structure of its tongue, ib. ; its 
 honey bag, x. 12 ; architecture, x, 
 18. ; houses, their forms, x. 98; its 
 Btomach, x. 12 ; its antenna, ib. ; 
 its wings, ib. ; legs ib. ; feet, x. 
 13 ; varieties of, x. 6 ; wax-makers 
 produce honey, x. 35; characteris- 
 tics and habits of worker-bees, x. 
 77 ; first operations of wax-makers, 
 x. 35 ; kneading of wax, x. 3G ; 
 first construction of hive-wall, ib. 
 Beetle, blind as, error of the phrase, 
 ix. 203. 
 
 Brine pumps for marine engines, x. 
 141. 
 
 Burnens, See Huber. 
 
 Black Sea, ix. 142. 
 
 British India — Deckan -plateau, ix. 
 
 146-7. 
 "British Isles, ix. 140. 
 
 Camera lucida, measurement by, ix. 
 56. 
 
 Campbell's Pleasures of Hope, lines 
 from, ix. 204. 
 
 Carpenter bee, x. 21. 
 
 Caribbean Sea, ix. 151. 
 
 Caspian Sea, ix. 142. 
 
 Cells of honeycomb, x. 55 ; of bees, 
 royal and nymph, x. 53. 
 
 Centering of lenses, ix. 20. 
 
 Central America, ix. 150. 
 
 Chromatic aberration positive, ix. 15 ; 
 negative, ib. 
 
 Chemical phenomena, method of adapt- 
 ing them to microscopic observation, 
 i^, 75. 
 2 
 
 Chevalier's universal microscope, ix. 
 72. 
 
 Chippewayan and Rocky Mountains, 
 ix. 151. 
 
 Climate, its dependence on latitude, 
 ix. 1G5 ; explained by the varying 
 positions of the earth, ib. ; deter- 
 mines the disti-ibution of plants and 
 animals, ix. 179; dependent on ele- 
 vation, ix. 178 ; local character of, 
 ix. 181. 
 
 Clouds, effects of, ix. 182 ; their 
 electricity, x. 180 ; their induc- 
 tive action on the earth, x. 183. 
 
 Cocoons, temperature of, how main- 
 tained, X. 45. 
 
 Compressor, ix. 40. 
 
 Condition, social, of a people indicated 
 by their buildings, x. 18. 
 
 Conductors for the protection of 
 buildings, x. 184. 
 
 Continents, average height of, ix. 188. 
 
 Cordilleras, ix. 152. 
 
 Corrosion of marine boilers, x. 143. 
 
 Clothier bee, x. 20-1. 
 
 Clyde, steamers on, x. 114. 
 
 Cricket, Shakspeare's allusion to, ix. 
 202. 
 
 Crustaceous animalculse, ix. 93. 
 Cunard steamers, x. 119. 
 Current, voltaic, apparatus for apply- 
 ing, ix. 41. 
 Cyclops minutus, ix. 26. 
 
 Dardanelles and Bosphorus, ix. 
 
 141-2. 
 Diaphragms, ix. 31. 
 Diffi-action and interference, effects of, 
 
 ix. 45-6. 
 
 Dog and shadow, optical error in the 
 
 fable of, ix. 193-4. 
 Dog-days, ix. 169. 
 
 Double refracting crystals, their effect 
 upon rays of light, ix. 68. 
 
 Dragon fly and its larva, ix. 89. 
 
 Drone cells and worker cells, x. 33. 
 
 Drone, head of, magnified, x. 11. 
 
 Drones, x. 9, 52 ; their treatment 
 and massacre, x. 75. 
 
 Earth, surface of, ix. 130 ; relief 
 of, 186-7 ; position of, on June 21, 
 ix. 167 ; on December 21, ix. 170; 
 thermal eBfects of a uniform surface, 
 
mDEX TO VOLUMES IX. AND X. 
 
 ix. 183 ; why this regularity does 
 not prevail, ib. ; its position at the 
 autumnal equinox, ix. 168; diur- 
 nal and nocturnal phenomena by 
 which the different months are 
 characterised, ix. 173; illustration 
 of its varying position in the suc- 
 cessive months, ix. 171-2-3. 
 
 Eastern continent, ix. 157 ; in South 
 America, ix. 158. 
 
 Electro-magnets, property of, x. 196 ; 
 their application as a moving 
 power, X. 197. 
 
 Electro -motive power, x. 193. 
 
 Encounter steamer, engines of, x. 169. 
 
 Europe, outlines of, ix. 140. 
 
 Eye-glass of microscope, ix. 2. 
 
 Eye, protection of, ix. 46-7. 
 
 Eye-piece of microscope, ix. 25. 
 
 Fairbairn, his internal gearing, x. 
 167. 
 
 Feathering-paddles, objections to, z. 
 156. 
 
 Field of view, actual dimensions of, 
 ix. 26. 
 
 Field glass of microscope, ix. 4. 
 Florida, peninsula of, ix. 155. 
 Flowers propagated by means of bees, 
 X. 79. 
 
 Focussing, ix. 27-8, 35. 
 France, ix. 140-1. 
 
 Froment, his electric telegraph, x. 
 
 205 ; his microscopic writing, x. 
 
 207 ; his electric clocks, x. 208 ; 
 
 his workshop in Paris, x. 195. 
 Fuel, its economy in marine engines, 
 
 X. 143. 
 Fulgurites, x, 183. 
 Furnace of marine engines, x. 146. 
 
 Geared engines, x. 166. 
 Geographical terms, ix, 131-2. 
 Geography, preliminary knowledge of, 
 
 ix. 130 ; origin of the name, ix. 
 
 130. 
 
 Geometrical problem of the globe 
 
 solved, X. 31-2. 
 Glow-worm, Moore's allusion to, ix. 
 
 203. 
 
 Goniometers, ix. 58. 
 Goring, Dr., experiments of, ix. 13. 
 Great Britain Steamer, engines of, x. 
 169. 
 
 Great eastern continent, Lt. 3!?. 
 Greece, ix. 141. 
 Greenland, ix. 155. 
 Gulf of Mexico, ix. 151. 
 Gulf stream, ix. 191. 
 
 Hearing of bees, x. 91. 
 
 Heat evolved in respiration from the 
 bee-hive, x. 46. 
 
 Heat received from celestial spaces, 
 ix. 181. 
 
 Hebrew scriptures, x. 2. 
 
 Hellenic peninsula, ix. 156. 
 
 Hemisphere of most land, ix. 156. 
 
 Hexagonal form, great advantages of, 
 for cells, X. 30. 
 
 Hymenoptera, x. 5-6. 
 
 Himalayas, animals inhabiting them, 
 ix. 181 ; vegetation of, ix. 178-9. 
 
 Hive-bee, x. 25 ; structure of its 
 comb, X. 25-6 ; double layer of 
 cells, X. 27 ; pyramidal bases of 
 their cells, x. 27 ; illustrative 
 figures of the same, x. 28-9 ; sin- 
 gle cells, X. 29 ; combination of 
 the same, x. 29-30 ; various 
 forms of their hives, x. 99 ; how 
 ventilated by bees, x. 89. 
 
 Honey, its production and varieties, 
 X. 106. 
 
 Honeycombs, construction of, x. 34- 
 56 ; process of forming the same 
 not merely mechanical, x. 40. 
 
 Horse -power, real and nominal, x. 
 172. 
 
 Huber, anecdote related by, x. 45, 3 ; 
 his servant Burnens, ih. ; curious 
 history of his blindness, ib. ; his 
 wife and son, x. 4 ; pursuit of his 
 researches, x. 4-5. 
 
 Humble bees, females of, x. 44 ; their 
 nursing workers, ib. ; their trans- 
 formation, X. 45. 
 
 Hudson, steamers on the, x. 114. 
 
 Hydrometric indicator of steam boilers, 
 X. 137. 
 
 Ikdia, Further, ix. 156. 
 Illumination, Prichard's analysis of 
 
 the effects of, ix. 47-8, 50. 
 Insects, structure of, x. 5 ; plan of 
 
 their anatomy, x. 5 ; their senses, 
 
 X. 86. 
 
 3 
 
INDEX TO VOLUMES IX. AND X. 
 
 Johnston's physical maps, ix. 185. 
 
 Land and water, distribution of, ix. 
 130. 
 
 Land, relief of, ix. 132 ; outlines of, 
 ix.l54. 
 
 Lardner, Dr., his opinions on the 
 Atlantic steam voyage, x. 118. 
 
 Leaf-cutter bees, x. 23 ; their man- 
 ner of making their nest, ib. ; 
 their process of cutting the leaves, 
 X. 24. 
 
 Lens, method of determining its 
 angular aperture, ix. 13 ; mutual 
 chromatic and spherical correction 
 of, ix. 15. 
 
 Lewenhoeck, experiments by, ix. 51. 
 
 Lieberkuhn, uses of, ix. 45. 
 
 Light and shade, varying eflfects of, 
 ix. 44. 
 
 Lightning, its effects, x. 187 ; form 
 
 of its flash, X. 181. 
 Linceus sphericus, ix. 92. 
 Lottin, his account of the aurora 
 
 borealis, x. 189. 
 Llanos of Orinoco, ix. 153. 
 Lurco, or glutton, ix. 93. 
 
 Madagascar, ix. 142-3-4. 
 
 Ma.cnifying-glasses are simple micro- 
 scopes, ix. 2. 
 
 Magnifying powers, a term much 
 misunderstood, ix. 59 ; various 
 ones adapted to the same micro- 
 scope, ix. 23. 
 
 Maps and globes in relief, ix. 115. 
 
 i\Iarine engine, x. 125 ; details of its 
 structui-e, x. 129; proportions, x. 
 148 ; expansive action in, x. 147. 
 
 !Marks, Professor, and Dr. McCaul, 
 their examination of the true mean- 
 ing of the oi'iginal Hebrew of the 
 description of the war-horse in Job, 
 ix. 208. 
 
 Mason-bee, x. 21. 
 
 Measurement distinct from magnify- 
 ing power, ix. 50, 
 
 Mediterranean, ix. 139. 
 
 Microscope, origin of term, ix. 2 ; 
 simple ones, magnifying-glasses, ix. 
 2 ; mounting of, ix. 69 ; condi- 
 tions of efficient mounting, ix. 70 ; 
 4 
 
 FrauenhofFer's mounting — method 
 of determining the magnifying 
 power by the Camera lucida, ix. 
 62 ; double microscope, ix. 86 ; 
 Mr. Nachet's microscope, ix. 85 ; 
 Chevalier's method of mounting it, 
 ix. 72 ; of rendering it vertical, ix. 
 74 ; binocular, ix. 87 ; Varley's, 
 ix. 85 ; the illuminators, ix. 29 ; 
 general description of reflecting, ix. 
 
 5 ; condition of distinct vision, ix. 
 
 6 ; different eflfects of magnifying 
 powers, ix. 8 ; multiple, ix. 85 ; 
 triple and quadruple, ix. 87 ; 
 Smith and Beck's, ix. 82 ; general 
 description of compound, ix. 2 ; 
 fine adjustment, ix. 36 ; course, 
 ib. ; slides to be cleaned, ix. 40 ; 
 their adaptation to chemical and 
 medical purposes, ix. 88. 
 
 Micrometers, ix. 53 ; Le Bailif e, ix. 
 54 ; Jackson's, ix. 55. 
 
 Micrometric scales, ix. 51. 
 
 Micropolariscope, ix. 65. 
 
 Microscopic objects, method of deter- 
 mining the least which a given 
 power can render visible, ix. 63 ; 
 method of condensing light upon it, 
 ix. 75-6; curious effects of light 
 upon, ix. 42 ; measurement of, ix. 
 50-1 ; Ross's glass, ix. 2, 22 ; com- 
 pound object, ib. ; preparation of, 
 ix. 28 ; illumination of, ix. 42 ; 
 means of moving and illuminating 
 it, ix. 27 ; support and movement 
 of, ix. 35; generally translucent 
 or may be made so ; ix. 43 ; 
 method for determining its relief, 
 ix, 37 ; difficulty of bringing it 
 into the field, ix. 37 ; mechanism 
 for accomplishing this, ix. 38 ; to 
 be successively viewed by increasing 
 powers, ix. 40. 
 
 Mississippi, source of, ix. 162 ; its 
 tributaries, ix. 159; great valley 
 of, ix. 153. 
 
 Missouri and its tributaries, x. 162. 
 
 Aloral suggested by the economy of 
 nature, x. 1. 
 
 Moore, scientific errors in his Irish 
 Melodies, ix. 197 ; physical impos- 
 sibility of what the poet supposes, 
 ib. ; * ' Thus when the lamp that's 
 lighted," allusion is explained, ix. 
 
INDEX TO VOLUMES IX. AND X. 
 
 198 ; " While gazing on the moon's 
 light," sound astronomy, ix. 201 ; 
 allusion to the glow-worm, ix. 
 203. 
 
 Months, diurnal and nocturnal phe- 
 nomenon by which they are cha- 
 racterised, ix. 173, 
 
 Mountain ranges not uniform, ix. 
 185-6 ; new ones possible, ix. 188; 
 effect produced by contemplation 
 of, ix. 187. 
 
 Mungo Park, anecdote of, x. 110. 
 
 North American Peninsula, ix. 154 ; 
 its extent and limits, — its political 
 divisions, ix. 150-1 ; eastern plain 
 ^of, ix. 153. 
 
 Northern hemisphere, days longer 
 
 than nights in, ix. 167. 
 Norway and Sweden, ix. 140. 
 Nymph of bee, x. 54 ; of the 
 
 white ant, ix. 100. 
 
 Ohio, ix. 160. 
 
 Old and new continents, relation be- 
 tween the coasts of, ix. 151. 
 Orinoco, ix. 163 ; Eio de la Plata, ib. 
 
 Paddle-wheel, common, x. 126, 
 150 ; feathering, x. 153 ; split, 
 X. 155 ; American, x. 156. 
 
 Pampas of Patagonia and Buenos 
 Ayres, ix. 153. 
 
 Parallel ridges of mountains, effects 
 of, ix. 158. 
 
 Peninsula, prevalence of its form, ix. 
 154 ; Crimean, South American, 
 North American, Florida, Lower 
 California, Greenland, Africa, Aus- 
 tralia, New Zealand, Spain and 
 Portugal, Italy, Hellenic, Norway 
 and Sweden, Europe, India, Fur- 
 ther India, ix. 154-5-6. 
 
 Peteroff steamer, its engines, x. 149. 
 
 Philiscus, X. 3. 
 
 Philosophical instruments graduated 
 by electro-motive power, x. 202. 
 
 Plains and lowlands, ix. 132 ; Plum- 
 per steamer, engines of, x. 171. 
 
 Polarised ray, condition of, ix. 60. 
 
 Polarisation, ix. 65 ; by double re- 
 fracting crystals, ix. 67. 
 
 Polynesia, ix. 148. 
 Potosi, ix. 152. 
 Prairies, ix. 153-4. 
 Primogeniture adopted among bees, 
 X. 58. 
 
 Propellers, submerged, x. 157. 
 
 Pritchard, Mr., his method of ascer- 
 taining the greatest angle of which 
 a given lens is capable, ix. 13 ; his 
 analysis of the effects of illumina- 
 tion, ix. 47-8-9-50. 
 
 Pyrenees, ix. 187. 
 
 Queen-bee, her numerous suitors, x. 
 7 ; her chastity and fidelity, x. 8 ; 
 her fertility, ib. ; her first laying, 
 ib. ; royal eggs, ib. ; royal cham- 
 ber, ib. ; effect of postponement of 
 her nuptials, x. 9 ; mutual hos- 
 tility of queens, x. 58 ; their treat- 
 ment, X. 60 ; her fecundity not 
 anomalous, x. 17 ; her character 
 and jealousy, x. 57 ; respect shown 
 to her corpse, x. 75. 
 
 Quetelet, his observations on atmos- 
 pheric electricity, x. 179. 
 
 Rattler steamer, experiments on, x 
 163. 
 
 Reflectors, oblique plane, ix. 34. 
 
 Rivers, beds of, banks, tributaries, 
 valleys, water-sheds, delta, estu- 
 aries, friths, ix. 136-7 ; of the 
 world, their general plan, ix. 165 ; 
 formation of, ix. 157 ; river sys- 
 tem of Europe, ix. 163. 
 
 Ross's microscope, ix. 78 ; his useful 
 labours, ib. 
 
 Romas, his experiments, x. 180. 
 
 Satyr, ix. 91. 
 
 Savannahs, hill-nests of white ants 
 in them, ix. 117. 
 
 Scandinavian peninsula, ix. 156. 
 
 Science and poetry, ix. 193. 
 
 Screw propellers, x. 158 ; sub- 
 aqueous, X. 122. 
 
 Screw propeller, its application, x. 
 165. 
 
 Screw engines, various forms of, x. 
 170. 
 
 Screw vessels, their speed, x. 168. 
 
 6 
 
INDEX TO VOLUMES IX. AND X. 
 
 Shakspeare's allusion to tlie economy 
 
 of the bee, ix. 203. 
 Shortest day not the coldest, cause, 
 
 ix. 170-1. 
 Siamese engines, x. 147. 
 Sicily, ix. 141. 
 
 Smeathman's microscope, destruction 
 of, ix. 119 ; curious experiment 
 of, ix. 125. 
 
 South American peninsula, ix. 154, 
 149. 
 
 Spain and Portugal, ix. 141, 155. 
 
 Spring equinox, ix. 166. 
 
 Steam navigation, x. 113 ; its pro- 
 gress, X. 116. 
 
 Steam boilers, incrustation of, x. 
 136 ; flue and tubular, x. 131. 
 
 Steam navy, strength of, x. 174. 
 
 Store cells of bees, x. 34 . 
 
 Summer warmer than the spring, 
 cause, ix. 169. 
 
 Sun vertical at the equator, oblique 
 at all other points, ix. 167 ; its 
 thermal influence in difierent lati- 
 tudes, ib. 
 
 Swarming of bees, x. 67. 
 
 Table showing the reflection at dif- 
 ferent obliquities, ix. 194. 
 
 Taste of bees, x. 91. 
 
 Temperate zone, ix. 175-6. 
 
 Temperature depends on sun's alti- 
 tude and length of day, ix, 167. 
 
 Terrestrial surface, undulations of, 
 ix. 130. 
 
 Termes embia, ix. 97. 
 
 Termes fatalis, or bellicosus, ix. 97. 
 
 Thermal influence greatest on 21st 
 June in northern hemisphere, ix. 
 169. 
 
 Thorley, anecdote of, x. 111. 
 
 Thunder and lightning, x. 177. 
 
 Torrid zone, ix. 174-5 ; sun vertical 
 in it twice a-year, ix. 175. 
 
 Ti'ansmission and reflection, illumina- 
 tion by, ix. 42. 
 
 Tropics, the sun can only be vertical 
 within them, ix. 171 ; animals of, 
 ix. 181. 
 
 Tubes of steam boilers, x. 135. 
 
 Upholsterer- BEK, x. 22 ; hangings 
 and carpets of her rooms, x. 23. 
 6 
 
 Vision of bees, x. 91. 
 
 Vision, distinct human, least distance 
 
 of, ix. 60. 
 Virgil, X. 3. 
 
 "War-horse, celebrated description of 
 in Job, ix. 207 ; unireaning lan- 
 guage of the translation, ib. ; exa- 
 mination of the original by Dr. 
 McCaul and Professor Marks, ix. 
 208 ; interpretation by Gesenius, 
 ib. ; by Elwald and Schultens, ib. ; 
 correct meaning explained, ib. 
 
 War vessels, application of steam to 
 them, X. 124. 
 
 Water fly, ix. 93. 
 
 West Indian Archipelago, ix. 154-5. 
 Western, or new continent, its extent 
 
 and form, ix. 149 ; relief of, ix. 
 
 151. 
 
 White ants, ix. 98 ; their mis- 
 chievous habits, ib. ; constitution 
 of their societies, ib. ; chiefly con- 
 fined to the tropics, ix. 99 ; use of, 
 as food and medicine, ix. 101 ; 
 their destruction of shelves and 
 wainscoting, ix. 120 ; their art- 
 ful process to escape observation, 
 ib. ; anecdotes of, by Koempfer and 
 Humboldt, ix. 120-1 ; their de- 
 struction of the governor's house at 
 Calcutta, ib. ; of a British ship of 
 the line, ib. ; their manner of 
 attacking timber in the open air, 
 ix. 122 ; extraordinary behaviour 
 of their soldiers v/heu a nest is 
 attacked, ix. 122 ; curious ex- 
 ample of the repair of a partially - 
 destroyed nest, ix. 125 ; curious 
 obsei'vation of marching Termites 
 by Mr. Smeathman, ix. 126 ; re- 
 markable conduct of their soldiers, 
 ib. ; rage and fury of their soldiers 
 when attacked, ix. 122-3 ; in- 
 dustry and promptitude in repair- 
 ing the damage done to their habi- 
 tation, ib. ; vigilance of their 
 soldiers during the process of re- 
 pair, ix. 123 ; conduct of their 
 soldiers during a second attack, ix. 
 124 ; difiiculty of investigating the 
 structure of their habitations, ib. ; 
 obstinate opposition of their sol- 
 
INDEX TO VOLUMES IX., AND X. 
 
 diers, ib. ; discovery of tlieir royal 
 chamber, ix. 124 ; fidelity of sub- 
 jects, ib. ; use of domic, the sum- 
 mit of their habitation, for the 
 preservation of the colony, ix. 107 ; 
 position, form, and arrangement of 
 their royal chamber, ib. ; its 
 gradual enlargement for the accom- 
 modation of the sovereign, ib. ; its 
 doors, ib. ; corridors and ante- 
 chambers surrounding the royal 
 chamber, ib. ; their nurseries, ib. ; 
 the walls and partitions of the 
 same, ix. 108 ; the position of 
 their nurseries varied, according to 
 the exigencies of the colony, ib. ; 
 continual alterations and changes 
 in their habitation, ib. ; peculiar 
 mould whicb coats tlieir walls, ib. ; 
 their store-room for provisions, ib. ; 
 inclined paths which approach 
 them, ix. 109 ; Gothic arches 
 which surmount their apartments, 
 ib. ; their subterranean passages, 
 galleries, and tunnels, ib. ; royal 
 body-guard, ix. 103 ; queen, her 
 vast fertility, ib. ; treatment of 
 tbeir king and queen, ix. 99 ; sol 
 diers, ix. 100 ; workers, x. 9 ; 
 gradients, or slopes, which regulate 
 covered ways, ix. 109 ; reflections 
 on their wonderful works, ib. ; 
 their formation of a covered way 
 when forced to travel above ground, 
 ix. Ill ; tenderness of their bodies 
 render covered ways necessary, ib. ; 
 slieir physiological characters, ix. 
 
 100 ; bridges by which they pass 
 from one part of the habitation to 
 another, ix. 109 ; use made of 
 their constructions by wild cattle, 
 ix, 106 ; Termes lucifugus, organi- 
 sation of their societies, ix. 117 ; 
 habits of their workers and sol- 
 diers, ib. ; materials used for 
 building, ib. ; construction of their 
 tunnels, ix. 118; Termes belli- 
 cosus, destructive habits of, ix. 
 119; their process of filling up 
 their excavations with mortar, ib. ; 
 Termes arborum, nests of them 
 roofs of houses, ix. 118 ; turre 
 built by Termes mordax, and 
 Termes atrox, ix. 114 ; thear 
 king, queen, workers, and soldiers, 
 ix. 116 ; habits of workers, ix. 
 99 ; figure of pregnant queen, ix. 
 102 ; vertical section of habi- 
 tation, showing its internal arrange- 
 ment, ix. 105 ; first establishment 
 of a colony, ix. 100-1 ; care be- 
 stowed on the queen's eggs by 
 workers, ix. 103; election of their 
 king and queen, ix. 102 ; figures of 
 tlieir king and queen, ix. 99 ; im- 
 pregnation of tbeir queen, ix. 102 ; 
 their constructions used to obtain 
 views seaward, ix. 106 ; first 
 establishment of a colony, ix. 
 100-1 ; nymphs, ix. 100. 
 
 White sea, ix. 140. 
 
 Winter season explained, ix. 170-1. 
 
 Winter, phenomena of, in the southern 
 hemisphere, ix. 170. 
 
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 Robson, B.A. izmo. 3s. 6d., cloth lettered. 
 
 CONSTRUCTIVE GREEK EXERCISES, for 
 
 Teaching the Elements of the Language, on a System of 
 Analysis and Synthesis, with Greek Reading Lessons and 
 copious Vocabularies. By John Robson, B.A., London, 
 late Assistant-Master in University College School, 
 izmo., pp. 408. 7s. 6d., cloth. 
 
 New Latin Exercises. 
 
 ANALYTICAL LATIN EXERCISES. By 
 C. p. Mason, B.A., Fellow of University College, 
 London. i2mo. 3s. 6d., cloth. 
 
 These Exercises are based, as regards the Accidence, on the Crude 
 Form system, which is so applied that the work may be used in connexion 
 with any of the best school grammars in current use. The study of the 
 Accidence is succeeded by a systematic development of the formation 
 and meaning of compound and derived words. The general object of 
 the book is to give the learner a clear understanding of the formation and 
 sense of the words of the Latin language, and of the constructions in 
 which they are employed. 
 
 WERTHEIMER, LEA AND CO., PRINTERS, FINSBURY CIRCUS.