Geology Library K 55 887 % i 0! : 3 6 9 1 /<^y^- o BEUIOGr-aEOPHYSICS iibrkry mmERSITY OF CALIFORNIA 405 HILGAPD AVE. lOSMGELES, CAIUK, 90024 REVISED EDITION', Ph 7 sica 1 BY M. F. MAURY, LL.D., AUTHOR or "PHYSICAL OEOGRAPHT OP THE SEA," LATE SUPERINTENDENT OP THE NAVAL OBSERVATORY, WAsqiNGTON, D. C, I^tc. REVISED BY MYTTON MAURY, U.D. UNIVERSITY PUBLISHING COMPANY, New Yokk. 1887. MAURY'S GEOGRAPHIES NEAV SERIES. ELEMENTARY GEOGRAPHY: A revision and abridgment of the "First Lessons" and the "World We Live In." Designed for Primary and Intermediate classes. The style is familiar and interesting. The arrangement of the text is in harmony with the latest and best methods of instnietion. New Maps and numerous illustrations. MANUAL OF GEOGRAPHY-REVISED: A complete Treatise on Mathematical, Physical, and Political Geography; in accord with the most recent methods of teaching. The subject is presented in a bright and attractive manner. Abundant explana- tions are employed to awaken and sustain the interest of the pupil in intelligent study. Beautiful new Maps and Illustrations. PHYSICAL GEOGRAPHY— REVISED: In which the Natural Features of the Earth, its Oceanic and Atmospheric Phenomena, and its Animal and Vegetable Life, are fully treated. The frosh, attractive style of the work and the interest of its detail charm the pupil and the general reader. Illustrated with numerous beautiful Maps and Engravings. WALL MAPS : With new and original features ; furnishing invaluable aid in teaching Geography in classes, and comprising, I. The World. II. North America. 111. The United States. IV. South America. V. Europe. Vi. Asia. VII. Africa. VIII. Physical and Commercial Chart of the World. MAP-DRAWING: Prom Maury's Revised Manual of Geography. In ordering the Manual or the Physical, specify whether the revised or the old is wanted. OLD SERIES. FIRST LESSONS IN GEOGRAPHY. THE WORLD WE LIVE IN. MANUAL OF GEOGRAPHY. PHYSICAL GEOGRAPHY. In ordering the Manual or the Physical, specify whether the old or the revised is wanted. M. F. MAURY, In the Office of the Librarian of Congress, at Washin^on. Press of J. J. Little i C\*. Copyright, 1883, by the University Publishing Company, New York. j^^„, place. Ne* York. Library St / PREFACE, This volume, together witli the three graded Geographies previously published, and a treatise on Astronomy, forming the Author's contribution to the University Series of School Books, was commenced in 1806. It is the joint laboi of tiis wife, daugliters, anil self, and eonstitutod one of the chief souices of their homo recreation during their residence in England. There tlie best sources of information were kindly and freely opened to him. Tliis, combined witli the knowledge and experience acquired or perfected in the superintcndency, for fifteen years, of the Washington Observatory, made the undertaking congenial, and the occupation as charming as labors of love always are. The aim throughout the series has been to strip these two most important branches — Geography and Astronomy — of dry details and mere technicalities, to popularize these fields of knowledge, and make them as interesting and instructive to students as possible. The Author's investigations for his "Wind and Current Charts," in which he was aided by the vessels and governments of the maritime nations, and the insight that these gave him into the Physical Geography of the Sea and its Meteorology, also afforded him some rare advantages for preparing the present general treatise on Phy'sical Geography'. Besides these special and original sources of information, he has, in the preparation of this work, had access to the best and choicest fountains of recent geographical and scientific knowledge, and has revised his MS. up to the date of going to press. A science of recent growth, Physical Geography depends for its truths and general principles upon extensive and prolonged observations. These observations have been made for too short a time and over too limited an area, to furnish more than the basis for a complete science. The quickened and enlarged interest that has been awakened in physical researches, the more perfect instruments and appliances that are now used and that will be still further improved, and the patronage and encouragement of enlightened governments, will doubtless lead to the solution of many of its yet unsolved problems. It has been one of the great aims of the author of this book to prepare its readers and students to understand and take an intelligent interest in this noble science, and especially to awaken in the minds of the young that spirit of observation and patient inquiry which has already won from nature so many of her most hidden secrets. In the preparation of the numerous charts which enrich the volume, the author has had the assistance of one of the most accomplished chartographers of the country ; and the sldll and beauty with which they havs been engraved upon copper are very gratifying. The pictorial illustrations, which so abundantly explain the text and adorn the pages, have been designed and engraved by some of the first artists in the country, or obtained from European sources, and testify to the liberality of the publishers, and their purpose to present this work to the public in a most attractive garb. M. P. MAURY. Lbxington, Virginia, November, 1872. PREFACE TO THE REVISED EDITION. The progress of science anticipated by the author in the foregoing preface, has rendered desirable the preparation of a revised edition of the Physical Geography. While engaged in this labor, the reviser has sought to meet the demands of our schools for brief books by abridging somewhat the earlier edition, without, however, impairing its completeness. To a considerable extent a re-arrangement of the materials has been adopted. But the aim has been thioughout, to preserve, so far as possible, the charm of the author's style. The typographical arrangement of the text, the topical analysis at the end of each chapter, and the test questions wiU, it is believed, greatly facilitate the use of the book in the class-room. In the prosecution of the work the reviser has invoked the counsel of many eminent scientists and experienced educators. To them all he begs to express his obligations for their valuable suggestions. The book owes much to their kind assistance. It is hoped that it will be found abreast of the times, and well adapted to lighten the labor of the teacher, and to kindle the interest of the pupil. MYTTON MAURY. CONTENTS, PART I. THE EARTH. PAOE I. The Earth as a Planet 6 II. Plani'tary Movements 8 ni. Magnetism of the Earth 10 IV. Internal Heat of the Earth 13 V. Volcanoes 15 VI. Earthquakes 21 PART II. THE LAND. I. Arrangement of Land Masses 26 II. Forms of Land 27 III. ReUef Forms of the Continents 30 IV. Islands 38 I^ART III. THE WATER. I. Properties of Water 43 II. Waters of the Land 45 III. Drainage 50 IV. Continental Drainage 51 PAOB V. TheSea 52 VI. The Oceans 54 VII. Waves and Tides 55 VIII. Currents of the Sea 61 PART IV. THE ATMOSPHERE. I. Physical Properties of the Atmosphere 69 II. Climate 70 III. Winds and Circulation of the Air 75 IV. Storms 81 V. Moisture of the Air 85 VI. Hail, Snow, and Glaciers 94 VII. Electrical and Optical Phenomena 98 PART V. LIFE. I. Relations between Plants and Animals 101 II. Range of Plants and Animals 102 III. Man 116 IV. Geographical Distribution of Labor 121 LIST OF CHARTS. Solar System 7 Lines of Equal Magnetic Declination 12 Distribution of Volcanoes 19 The World 24, 25 North America 30 South America 32 Europe 33 Asia 35 Africa 37 Australia 37 Thermal and Tidal Chart 59 Currents of the Sea and Drainage of the Land. 02, 63 Isothermal Lines and Zones of Temperature . . 72, 73 Winds 79 Rains 90,91 Distribution of Principal Vegetable Growths.104, 105 Distribution of Beasts. Birds, and Fishes, . ..110, 111 Distribution of the Races of Men 119 Principal Industrial Pursuits of Different Coun- tries 122, 123 RECENT FACTS CONCERNING PHYSICAL GEOGRAPHY A SV 1'1'l.i: M E X T TO MAUIiVS I'JIYSfCAL (I K (id h' A ]■ II Y Course of the Guff Sfreiim. — Tho (lieorv that a portion of tlie wiiters of the Gulf Stream makes the circuit of the Gulf of Mexico has of late been called in question. In this connection the following letter from 15. A Colonna, Assist. Chief Officer in the U. S. Coast and Geodetic Survey Department, is exceedingly interesting and important : U. S. Coast and (iEouETic Survey Office, Washington, November 34;A, I8fl' ,( Dear Sir: — Your letter of 17th inst. was duly received by Superintendent Thom who referred it to this Office. Press of work on my return from a short leave has pre- vented earlier attention. I now have the honor to say by direction of the Superintendent that fhe exact facts in re- gard to the circulation of the water in the (riilf of Mexico cannot he stated ; we have not had sufficient observations. The observations of deep sea curieuts, and the usual sound- ings were, during the season of ly85-6, confined to the Gulf Stream, on a line from Cape Florida (Fowey Rock Light House) to Great Bahamas ; during the season of 1886-7 the work was confined to the vicinity of west end of Cuba, Key West, and Yucatan. None of this work has been published, and none of it would shed any particular light upon the question jiropounded by you as to the circulation of the waters in the Gulf of Mexico. Our late explorations indicate that the axis of the Gulf Stream hugs the west coast of Cuba closely, and that the Gulf Stream currents are much influenced by the moon in accordance with her time of transit and her declination. So far as the Gulf of Mexico is concerned I do not think that there is any circular, well-defined current about its eircumferenoe. The warm surface water probably flows more freely toward the west coast of Florida than it does toward the coast of Texas or of Mexico. Although this view is founded somewhat on climatic and tidal indications, it is largely inferential. As 1 have said before, the matter is now mider consideration ; when we know more about what takes place at the east end of Cuba and thence westward along its north shore to the Strait of Florida, we will be ready to give more particular attention to matters in the Gulf. The great flow of water through the Strait of Florida, northward, must be supplied from somewhere ; its surface temperature indicates its recent arrival from the tropics, presumably set into the Carilabean Sea, and up into the Gulf of Mexico, by the trade-winds, and thence pro- pelled in accordance with the laws of fluid motion. Whether the whole supply of water for the Gulf Stream reaches the Florida Strait around the west end of Cuba, or not, cannot now be asserted. It is hoped that the season's work of 1887-8 will shed light upon this subject. Yoiu-s, respectfully, B. A. COLONXA. The I'etoeiti/ of the Gulf Stream. — Recent ob- servations of Lieutenant I'illsbury. of the United States Navy, show that the velocity of the (iulf Stream varies with the position of the moon. "The greatest velocity is about nine hours before the upper transit of the moon. The strongest surface current observed was five and one-fourth knots — the weakest, one and three-fourths — the average three and six-tenths knots." These results are, as a rule, higher than those hitherto given. It appears also that the speed of the surface water of the Gulf Stream is retarded perceptibly by northerly and north- easterly winds, and accelerated by those from the south- west. During the coming winter the United States vessel Blake, under command of Lieutenant Pillsbury, will continue to investigate the Gulf Stream current. She will anchor six hundred miles north-east of Harbadoes. during January and the first part of February, and will be in the track of ships from South Atlantic ports to the United States. The last part of February and until May she will be between the West India Islands, beginning at Trinidad and ending at the cold Bahama Channel. It is expected that Lieutenant Pillsbury's report will be of value, and that some points regarding the Gulf Stream currents will be de- termined with greater exactness than as yet is possible. Earlij Polijnesian Ndviyation. — Mr. Formander lias recently made some interesting and instructive discov- eries in the folk-lore of the Polynesian islands. He says that "from about the commencement of the eleventh cent- ury, for two or thrPfe hundred years, the folk-lore in all the [)rineiiial groups becomes replete with the legends and songs of a number of remarkable men, of bold expeditions, stirring adventures, and voyages undertaken to far-off lands.'' For seven or eight generations, the navigators of the lead- ing groups, from the Sandwich Islands in the north to the Society group in the south, and from the Friendly Islands in the west to the Marquesas in the east, were accustomed to interchange visits, and to voyage freely to and fro. with far more assurance and better seamanship than were dis- played by the early Greek and Italian sailors in the Medi- terranean. Yet the distances thus traversed sometimes exceeded 2.000 miles, and crossed the region of both the north and the south trade winds, and the equatorial calm belt. Such facl:s show that, in accounting for the movements of population in primitive times, mere distance and difliculties of navigation need hardly be taken into account. The pos- sible bearing of this upon such questions as the Asiatic origin of the North American Indians will at once be seen. Sea-level. — Recent observations seem to indicate that along the coast there is no such thing as the popular sea- *t 097 CopjTJ^ht, 18H7, 1>y the University Publishing Company, New York. \ RECENT FACTS CONCERNING PHYSICAL GEOGRAPHY. level." The surface of the sea at any given point on a coast will be higher or lower in pioportion to the situation and altitude of the neighboring land-masses. Lofty mountains attract the water and elevate the sea- level above the average height. It is considered, therefore, that the water, being attracted by the enclosing continents, the surfaces of the ocean ureas are lower in the centre than at tiie sides. The dcpi-ession of the Atlantic centre is esti- mated by some to be ten or twelve feet ; by others far more. Great Suit L,(ike is said to Iiave increased about twelve feet in depth during the last twenty years. Its greatest depth is only forty feet. The la'ie contains no living thing excepting infusoria of jjoorly ilefined form, but full of ac- tivity. The finest-developed was about tliree-fourths of an inch in length, and was shaped somewliat like a lobster. A Cliff of Glass. — line of the wonders of the Yellow- stone Park is a cliff of obsidian, which Prof. Joseph P. Id- dings, of the U. S. Geological Survey, says "is as true glass as any artificially manufactured." The cliff is about half a mile long by from 150 to 200 feet high, and presents a partial section of a surface flow of obsidian which poured down an ancient slope from the plateau lying east. Velocifi/ of Advance of Ci/cloiiic Storms.— The average progressive velocity of cyclonic storms is given by Professor Loomis as follows : Bay of Bengal and China Sea, 8.4 miles per hour ; West Indies, 18.7 ; Europe, 1G.7 ; mid- dle latitudes of Atlantic Ocean, 18.0 ; United States. 28.4. Our lake region seems, therefore, to possess the unhappy pre-eminence of being visited by the fastest-moving, as well as the most numerous storms in the world. " Lost Mi vers. ''—NunKious "lost rivers" occur in the southwestern portion of the United States. Among the tributaries of the Rio Grande, for instance, there are a num- ber wliich reach the main stream after a heavy rain, while at other times they are " lost " in a brackish marsh or small lake, or even in the sand of their own bed. One such stream is mentioned which thus disappeared within the space of twenty rods. The Krakatoa Eruption. — One of the most de- structive volcanic eruptions ever known occurred Aug. 27, 1883, in the island of Krakatoa (or Krakatau), in the Straits of Sunda, illustrating v-/hat is said in the text (p. 20), on the volcanic activity of this region. The small islands in the vicinity were covered to a depth of from ten to thirty meters with volcanic ashes and pumice, which also fell at sea for hundreds of miles in every direction. Two-thirds of the island were submerged, and the water now covers this a'ea to the depth of 150 to 1,000 feet. More than 40,000 human beings, overwhelmed by the waves or buried beneath falling cinders, perished on the neighboring islands and the adjacent shores of Java and Sumatra. Krakatoa itself was uninhabited- Months afterward, vast areas of the ocean, hundreds of miles away, were found nearly covered with floating pumice. Scientific investigation, made under the direction of the Dutch government, indicated that the height of the column of steam and smoke which arose from the crater was from nine to twelve miles, and the amount of solid matter thrown out, over four and a quarter cubic miles. The noise of the ex- plosions was distinctly heard hundreds of miles away. At Talcahuano, Chili, the ocean rose, on Aug. 28, two feet above high- water mark, indicating ttat the great wave caused liy the earthquake which accompanied the eruption, had traversed the entire breadth of the Pacific, The Oil Wells of Baku, on tin- west shore of the Caspian Sea, have reached a yield of a million tons per an- num. The earliest wells date ba(;k for centuries, but only within the last fifteen years has the work of obtaining the oil been actively ]irosecuted. A New Merv Ort«ts.— General Annenkoff, a Russian engineer, proposes to form, by irrigation, a new oasis 60 to 70 miles in length in southern Turkestan. He suggests diverting a portion of the; water of the Oxus into some an- cient channels running in the direction of Werv. The .soil is clayey, and, if watered, would, it is believed, prove highly fertile. The oasis of Khiva, and another near Merv, were formed in a similar manner. The Charleston Earth i/uakes.— Pot seveta,[ weeks, dating from October 31st, 1886, a large area of the United States, embracing nearly all the Atlantic Slope and a con- siderable portion of the Mississijipi Valley, has been visited by a series of earthquake shocks. The starling point of these disturbances was in the Caro- linas, and the city of Charleston and its neighborhood were -the scene of the most violent and disastrous visitations. Beyond this area, shocks of greater or less intensity were felt as far north as Vermont, and even in the Canadian Province of Ontario ; as far south as the Gulf of Mexico ; and as far west as Michigan and Missouri. The most violent shock occurred at 9.51 on the night of August 81st. Main Features. — As described by observers, the main features of the disturbance were as follows : (1.) A tremor, violent and destructive near the origin, and diminishing in intensity toward the outer bounds of the area disturbed. An observer at Charleston speaks of it as a " i-ude, rapid quiver," agitating the lofty strong-walled building in which he was, as though by the hand of some resistless power. "From first to last," he says, "it was a continuous jar, only adding force every instant, until at the point of maximum violence it seemed as though no human handiwork could withstand the shocks. The floors heaved under foot ; the walls and partitions visibly swayed to and fro." At Baltimore, a cool-headed observer records how, on the night of the earthquake, he was sitting with one leg thrown over and resting upon the knee of the other, when he noticed his suspended foot swaying at right angles to the direction of his body, with the regularity of a pendulum. At the same time he heard "a sonorous beating of some object" in an adjoining room, keeping time with the oscil- lations of his foot. Entering this room, he ascertained that the noise arose from the oscillations of his wardrobe, which was backed against the north and south wall of the room. The oscillations had been east and west, and had caused one of the doors of the wardrobe to tap against the partition between the two compartments, so producing the sonorous sounds alluded to. He found by experiment that it required a movement of half an inch at 6i feet from the floor to re- produce these sounds with the intensity observed during the earth-movement. Although it is generally true, as above stated, that the in- tensity of the tremor diminished toward the outer limits of the area of disturbance, it is of interest to notice that in this, as in the case of other earthquakes, there were, within the area of disturbance, many places where the shock was not felt at all. It is conjectured that such points owe their im- munity to geological peculiarities. (2.) The sound which accompanied the tremor was a sec- ond element in the phenomenon. This came from below. It resembled the rapid rolling of some heavy body over a floor. RECENT FACTS CONCERNING PHYSICAL GEOGRAITIY. or the booming of distant cannon. Liko the tremor, it was continuous, and became a "long roar and grinding like ten thousand rusty chariots on a rocky road." The ileslrtw/ire effects ot the cartli()uake wore nuiinly con- ftned to Charleston and SuMiiucrvilh', South Carolina. Nearly every buiklingof importance in the former ])laci! was more or less damaged — many were demolislied. Of the churclies, .scarcely any were left in a condition to be used. The wreck of private liouses was terrible. A recent visitor writes under date October 27 : " The accounlu have not been equal to what I saw. I think every building is more or less damagcid. Piles of debris are in every street." The terror of the unfortunate citizens cannot be conceived. Most of them passed the night of August 81, and several succeeding nights, in tlie streets and scjuares Many persons were injui'cil, and several were killed by the fall of the walls. The records show that this visitation is the ninth which has occurred at Charleston since 1754. It has been the only seriously disastrous one. Effect upon Domestic Animals. — Among the note- worthy incidents of the Charleston eartbijuake, were the effects produced upon domestic animals. The engine horses escaped and ran in wild affright, snorting and neighing, to the terror of all they passed. In the country the horses neighed out their distress, and the cows bellowed [)iteously. Animals that were stabled tried to l^reak away, and failing to do so, trembled and shivered in an agony of fear. Those that were at large fled to the woods and sought to hide themselves from the mysterious danger in thickets and swamps. Half an hour after the frightful shock, a savage looking, but completely scared mastiff, approached a re- porter in the city, and licked his shoes, in mute appeal for help. Cause of the Earthquake. — Little is accurately known as to the causes of earthquakes. An ingenious article appears in Science, October 29, I88(). by M. C. Meigs, in which the writer suggests that the phenomena of the Charleston earthquake may be all accounted for on the supposition that vast strata underlying the area of disturbance have been subjected to heat. This would occasion expansion of the part heated — then an outward thrust — then compression, becau.se the expanding portions would encounter resistance from outer masses not affected by the heat — then relief from compression by breakage. Experimental Illustration. — He considers that a paral- lel to this series of occurrences may be produced by holding a piece of glass (preferably plate), nearly horizontal, over the flame of an alcohol lamp. The portion heated will ex- pand ; compression will result, and in no long time the glass will break with noise and more or less shock. "Here," says the writer, " we have a working model illustrating all the reported phenomena of the Charleston earthquake." The suggestion is certainly deserving of consideration. Volcanic Activity. — It is worthy of notice, in con- nection with the Charleston earthquake, that there has been recently unusual volcanic activity in other parts of the world. In May, 1886, a grand eruption of ^tna took pla<;e. In .luly the terrible visitation occurred in New Zealand, which ranks as, perhaps, the most terrific of which we have record; and it is now reported that an eruption occurred on September 31st, on one of the Friendly group, by which seven native villages have been destroyed. And intelli- gence now reaches us that, on the morning of September 10th, over one hundred heavy shocks of earthqvmko oc- curred on the island of Ninafou, one of the Tonga group, and that from the bottom of the lake, which is 2.000 feet deep, a mountain has arisen to the height of 300 feet above its surface. Strange Internal Eruption. — Nine miles from Cimmaron, on the Denver and Rio Grande Railroad, in Colorado, the country has been visited by an internal erup- tion, which has displaced a tract about two miles square. The region w.as naturally hilly, with a heavy covering of trees. Where there had been hills, valleys now appear, while the valleys have been upheaved into hills. Trees stand in all conceivable positions, some of them being re- versed, with their roots free from dirt, the leaves and branches being buried in the debris. The water has dis- appeared from a large lake, the bed of which is tilted at an angle of 45 degrees. The whole section is so much changed as to make it unknown to those who were heretofore acquainted with it. Destruction of Wild Animals. — The wild ani- mals of North America, with tlie exception of a few species of birds, are rapidly diminishing in numbers, owing to their destruction by human enemies. Where, less than twenty years ago, millions of bisons were to be found on the west- ern " plains," there are now but small bands, remotely scat- tered, of a few dozen each. It is obvious, therefore, that in no long time, certain of our animal tribes will become ex- tinct. Deep-Sea Fauna. — The expedition of the Challenger in the years 1873-76, put us in possession of most important information regarding the animal forms which exist in deep- sea waters. It was conclusively established — (1.) That the distribution of living beings has no depth limit, but that animals of all the marine invertebrate classes, and, probably, fishes also, exist over the whole of the floor of the ocean. (3.) It appeared that the enormous pressure, the com- parative scantiness of light, and the differences in the chemical and physical conditions of the water do not in- fluence animal life to any great extent, for among the animals captured in the deepest hauls were species nearly allied to those found in shallow water. (3.) The interesting fact was presented that depths beyond 500 fathoms are inhabited throughout the world by a fauna which exhibits the same general features. In other words, deep-sea genera have usually a cosmopolitan exten- sion, and species are either universally distributed, or if, in remote localities, they differ, there is still a close resemblance among them. (4.) Some, though not many, types were found existing at abyssal depths which were pre\iously considered to be extinct. (5.) In its general character, the deep-sea fauna resembles most the fauna of the shallower waters of high northern and southern latitudes ; no doubt because the conditions of temperature, on which mainly the distribution of animal life depends, are nearly similar in extreme depths and ex- treme latitudes. The above and other conclusions, based upon the results of the Cluillenger expedition, have been, and are being, either confirmed or modified by the researches carried on by the United States Government. Methods of Work. — The methods adopted now are naturally more systematic, rapid, and effective than those employed twelve years ago on the Challenger. The steamer RECENT FACTS CONCERNING PHYSICAL GEOGRAPHY. Albatross has been specially constructed for the work of dredging, and she is manned by a very expert body of naval officers and scientists. Every summer, at least, she cruises in deep ocean waters, and brings back the results to the head- quarters of the United Stales Fish Commission, at Wood's Hole. In the Challenger expedition, only one deep-sea dredging could be made in a day, and very little of the bottom was secured at that. On the Albatross two to four dredgings per day are made in water over 1,000 fathoms deep, and five in water between 500 and 800 fathoms. It has been conclusively shown by these later researches that the proportion of animal life in ocean depths is far greater than was indicated by the Challenger's results ; and, furthermore, that instead of the abyssal forms being com- paratively small, many of them are even larger than the analagous forms existing in shallower waters. Among the echinodcrras (spine-covered animals, of which our common sea-urchin is a type), taken in depths of 1,346 to 1,735 fathoms, two species arc gigantic, one specimen l)eing eighteen inches long. Results. — Reporting the results of the work done in 1884, Professor Verrill says: "Many additions to the fauna of great depths were made, and a large jiroportion of them are undescribed forms. Some of the fishes were of great interest. Huge spiny spider-crabs, the outstretched legs of which measured over three feet from tip to tip, were taken in 1,000 to 1,230 fathoms, and another very large crab occurred in great abundance in 500 to 1,000 fathoms. Numerous spe- cies of shrimp, many of them bright -colored, and some of very large size, occurred, as usual in the deeper dredgings." "A striking characteristic of the deep-sea Crustacea." saysProfessor Verrill, " is their red or reddish color. A few species are apparently nearly colorless, but the great majority are some shade of red or orange ; and I have seen no evidence of any other bright color A few species from between 100 to 300 fathoms are conspicuously marked with scarlet or vermilion, but such bright markings are not noticed in any species from below 1,000 fathoms." Perhaps more remarkable than the matter of coloring is what we learn about the eyes of deep-sea forms of life. Of sixteen species taken below 2,000 fathoms by the Albatross every one had eyes, and these were distinctly faceted. " In at least three of these species (he eyes are not conspicuously different in size from those of allied shallow-water species." " However strong, therefore, may be the arguments of physicists against the possibility of light penetrating the depths from which these animals come, the color and struct- ure of their eyes, as compared with blind, cave-dwelling species, show conclusively that the darkness beneath 2,000 fathoms of sea-watei' is very different from that of ordinary cavenis." Jted Sunsets and SutiHses. — In the autumns of 1883 and 1884, the sky at sunset, and in a measure also at sunrise, was illuminated with a peculiar rosy light, which diffused itself far up toward the zenith. The phenomenon seems to have been observed all over the world. Various causes were assigned to account for it. Many scientific men considered that it was due to the presence in our atmosphere of minute volcanic dust emitted during the celebrated eruption of the volcano of Krakatoa, which oc- curred during the prevalence of the red sunsets. This ex- planation, however, must be abandoned, for the phenomenon made its appearance, certainly in one region of the world, long before the eruption. In the " Proceedings of the Manchester Literary and Phil- osophical Society, Vol. XXIII., Sessions 1883-4," is to bd found a letter dated Taranaki, New Zealand, in which the writer says that " for many weeks before that eruption this lurid glow was most strikingly jicrceiitible in New Zealand." In commenting on this letter, in his report for 1885, Dr. Draper, of theN.Y. Meteorological Observatory, says: " The latest opinion expressed l)y scientists is that the red sun- rises and sunsets were due to the earth passing through meteoric dust in space." And in explanation of the phe- nomenon being observed first in New Zealand, he says : ''May we not conceive that the earth in 1883 was passing through a meteoric cloud, and that the southern hemisphere was tlie first to enter that cloud ? " Tetnperatiire of Deep-sen Waters. — Observations made on the Albatross, during 1884. indicated that the temperature at depths of 2,000 to 2,G00 fathoms was about 87" Fahr. This temperature, however, was also found at the comparatively shallow depth of 1,000 fathoms Hence it would seem that, at least in the region of the observations alluded to. the minimum temperature is reached at 1,000 fathoms. The surface temperature taken at the same dates was about 72 Fahr. It is either owing to the cliange of temperature experienced in coming from great depths to the surface, or else to the removal of the pressure to which they have been previously subjected, that nearly all the deep-sea animals are dead when brought up in the trawl. Some have enough vitality to make a few feeble motions, but "in all cases they af)- peared," says Sir W. Thomson, "to have received their death-stroke before they had come out of the water." An exception to this general rule was the case of some coral polyps brought from a depth of 1,000 fathoms. These were alive aud expanded when placed in sea-water. Poiver of nil Ocean Jt'are. —In a paper by the Rev. Philip Neale, late British chaplain at Batavia, in Leisure Hour, speaking of the great inundation from the sea caused by the Krakatoa earthquake, Java, he says: ' ' One of the most remarkable facts concerning the inunda- tion remains to be told. As we walked or scrambled along, we were much surprised to find great masses of white coral lying at the side of our path in every direction. Some of these were of immense size, and had been cast up more than two or three miles from the sea-shore. It was evident, as they were of coral formation, that these immense blocks of solid rock had been torn up from their ocean bed in the midst of the Simda Straits, borne inland by the gigantic wave, and finally left on the land several miles from the shore. Any one who had not seen the sight would scarcely credit the story.* The feat seems almost an impossible one. How these great masses could have been carried so far inta the interior is a mystery, and bears out what I have said in preNious papers as to the height of this terrible wave. Many of these rocks were from twenty to thirty tons in weight, and some of the largest must have been very nearly double. Lloyd's agent, who was with me, agreed in thinking that we could not be mistaken If we put down the largest block of coral rock that we passed as weighing not less than fifty tons." * Compare page 21, paragraph 4, and examples on page 22. PHYSICAL GEOGRAPHY. Physical Geography invites you to consider tlie terrestrial machinery which makes day and night, seed-time and harvest ; whieli lifts the vapor from the sea, forms clouds, and waters the earth ; which clothes it with verdure and cheers it witli warmtli, or covers it with snow. Physical Geography treats of the agents that cause the wonderful circulation of the waters of tlie sea, that diversify the surface of the earth with nills and valleys, and embellish the landscape with rivers and lakes. Physical Geogi-aphy views the surface of the earth, its waters, and its enveloping atmosphere as the scene of the operations of great physical forces, which by their united action render possible the life of plants and animals. It studies the life of the globe whether on its surface or within its waters, taking note particularly of the circumstances wliich arc favorable or adverse to the development of organic forms. It is especially interested in the earth as the abode of man. Observing in careful detail the various features and agencies of our planet, it considers them as j)arts of a magnificent machine, by whose operations, under the guidance of the Great Designer, this planet is made a dwelling-place fit for man. It has been judged most convenient to present the topics treated in the following order : I. The Earth. II. The Land. III. The Water. IV. The Atmosphere. V. Life. PART I, THE EARTH. I. THE EARTH AS A PLANET, 1. What is the Barth ;'— The first question which requires to be answered iu discussing the Pliysical Geogrujjliy of tlie earth is, wliat is tlie eartli ? Ancient Theory. — Many centuries of Jiuman liistory passed before any one was able to answer this question correctly. Men saw the sun in the same part of the heavens morning after morning, and when his light faded, they observed that the stars were apparently just wliere tliey had been the night before. It was concluded that the sun EARTU AKD WOON IN SPACE and stars all moved round the earth once in twen- ty-four hours. Thus the early answer to our question was that the earth was the centre of the Universe. Careful observation seemed to confirm this idea. Astronomers watched the heavens. They mapped down the stars, and recorded from night to night the places of the brightest among them. They ob- served that some of them did not change their position with reference to their companions, while others very perceptibly varied theirs. The former were called fixed stars. Tlie latter received the name jjlanets, or wanderers, from a Greek word meaning to wander. What did their wandering mean ? It was found that after certain periods each of tlie jilanets returned to its old place in the heavens. This was deemed conclusive proof that the planets, together with the sun and moon, re- volved in circles round the earth. This explana- tion was satisfactory to the majority of mankind, but not to thoughtful astronomers. Theoey of Copernicus. — In 1542, Copernicus, a Prussian astronomer, startled the world by an- nouncing that the ancient theory was a mistake ; , . _ that the sun, not the earth, ■ is the centre of tlie Universe ; 1 tJiat the planets, instead of circling round the earth, re- volve round the sun ; and that the earth itself is only a planet. Thus the true answer to our question, learnt only about three hundred years ago, is that the earth is not utterly unlike the heavenly bodies, as it seems to us to be ; but that it is actually one of them, and that, if we were placed upon one of the other planets, the earth would appear as a shining star-like jjoint iu the sky. 2. Tite Solar System. — The Sun and its attendant planets with their satellites, together with the ^jlanetoids and comets, constitute what is known as the Solar System, so called from the Latin sol, the sun. A "system" consists of one central body, together with other smaller ones which move round it. The Sun. — The sun is the centre of the Solar System. From it all tlie jjlanets derive both heat and light. The sun is a vast sphere or ball, more than a million times as large as the earth. If we could place its centre where the centre of the earth is, then the sun would reach so far into space that it THE EARTH AS A PLANET. would extend almost 200,000 miles beyond the orbit of the moon. The sun is shown by the spectroscope to contain many of the same materials as those of which the earth is composed. It is in a state of intense heat, and columns of incandescent gases project from its surface tens of thousands of miles into space. The heat received in one year by the earth from the sun, than 200 in number. They are so small as to bo, for the most part, invisible to tlie naked eye. Tlic Secondary PUmets revolve round the Pri- mary Planets, as the Primaries revolve round the sun. They are also called moons and satellites. Our moon is the satellite of the Earth. The HiJndur Theory, which is held })y muiiy astronomers, supposes that all the botlies constituting the Solar System THE SOLAR SYSTEM. would, if distributed uniformly, melt a layer of ice 100 feet ihick eoveiing the entire globe. The Planets. — The planets are classed as Pri- mai-y and Secondary. The Primary Planets are eight in number. They are Mercury, Venus, the Earth, Mars, Jupi- ter, Saturn, Uranus and Neptune. These names are given in the order of their distance from the sun, Mercury being the nearest. Between Mars and Jupiter are the Planetoids, or Asteroids, more were originally one mass of matter in a nebulous or cloud- like condition. This was widely diffused through a certain portion of space, and had a rotary motion. From causes un- known to us, parts of it successively condensed and became semisolid. Being detached or thrown off from the general mass, these formed the various members of the Solar Sys- tem, the most distant from the centre being the earliest formed. The sun is considered to be a portion of the nebu- lous matter which is in an incandescent state, owing perhaps to chemical and physical changes going on among its ele- ments. PLANETARY MOVEMENTS. If the earth be represented by a globe one foot in diameter, the sun must be represented by a sphere 35 yards in diame- ter, and be 2^ miles from the globe, so as to sliow in proper proportion the real size of tlie two bodies and the distance between them. Jupiter, the largest planet, would be repre- sented by a globe 3i yards in diameter at the distance of 11 miles. The relative sizes of the disks ot the sun and planets are approximately represented below. RELATIVE SIZE OP THE SUN AND PLANETS. 3. Actual Size of the Barth. — The equa- torial diameter of the earth is 7,935. G5 miles ; the polar, 7,899.17. The difEerence is about 26^ miles. The region about each pole, therefore, must be com- pres.«ed 13:^ miles. The circumference of the earth at the equator is 24,899 miles. Itg volume, or solid contents,- is about 260,000,000,000 cubic miles. The specific gravity of the earth is about 5^, that IS, the earth is fire and a half times as heavy as a globe of water of equal dimensions would be. 4. Comparative Insignificance of the Earth. — If now we bear in mind that all the fixed stars are the suns of other si/stems resem- l)ling our own, and in many cases vastly larger * than our own, and reflect that the heavens above and below us are filled with untold numbers of such systems, we shall appreciate the comj^arative insignificance of our earth. The earth is only one of the smallest members of one of the numberless systems which fill the immen- sity of space. * The subordinate position of tlie Solar System in tlie universe is strongly suggested by tbe fact, that the entire system appears to be mov- ing through space in the direction of the constellation Hercules. Mo- tion towards indicates an attracting force ; and implies that the body exerting that force is larger than the body which is attracted. How vastly grander than our system must that one be which candraw toward Itself our sun with itii inconceivable volume, and the attendant planets I TOPICAL ANALYSIS. I. THK EARTH AS A PLANET. 1. What is the Earth 1 Ancient Theory. Fixed .Stars. Planett,. Theory of Copernicus. 2. The Solar System. Classesof bodies Included In it. The Sun. Ilelation to Solar System. Size. Materials composing it. Its heat. Planets. Primary Planets. Planetoids. Secondary Planets. Nebular Theory. Relative sizes of Sun and Planets. 3. Actual size of the Earth. Diameter. Circumference. \'oluine. Sjiccific gravity. 4. Comparative insignificance of the Earth. Test Questions. — [The test questions are to be used at the option of the teacher. They arc not directly answered in the text. Their design is to awaken thought on the part of llie pupil.] Name :dl the bodies yon can that may be seen in the heavens. What w ould be the consequence to the earth, if the lieat of the sun should be withdrawn » II. PLANETARY JIOVEMENTS. ]. Effects of the Earth's 3Iotions. — The nature of man requires for its highest development that he shall have certain alternations in the degrees of light and heat to which he is subjected. The planetary motions of the Earth produce just the changes which he needs. They are those of day and night, and summer and win- ter. Let us see how these are brought about. 2. notation. — All of the planets rotate on their axes from west to east.* This motion causes alternations of sunshine and darkness. The nearer a planet is to the sun, the less rapidly it rotates. Mercury, Venus, and the Earth rotate in about twenty-four hours. The more distant planets, so far as their rates have been ascertained, require only about nine or ten hours for their rota- tion. Their day is less than half of ours. It is easy to see that its brevity would be very inconvenient to beings like ourselves. ting. net^olntion. — The planets, while rota- also revolve round the sun. The direction of this planetary revolution is, like that of rotation, from west to east, and, with the exception of the satellites of Uranus, and possibly those of Neptune, all the secondary planets revolve . * An interesting evidence of the earth's rotation is that suggested by Newton. It is easy to see that a body at the top of a tower will, if the earth really rotates, move with greater velocity than will the base of the tower. Let a ball be dropped from the top of such a tower, and it will strike a point on the ground some distance from the foundation. Ei- periuienfs of this kind have all clearly demonstrated the easterly motion of the earth, the balls dropped always striking to the eastward. PLANETARY MOVEMENTS. ill the same direct-ion. Tlie time required for a single revoJution is called a year. The nearer a planet is to the sun, the more rapidly it revolves, and tlie shorter is its year. The year of Mercury, tlie nearest planet, is only eighty-eight days long : J upiter's year consists of about eleven of ours : Neptune's of more than 160. The earth completes its revolution in 365^ days. 4. Inclination of Planet avy Axes.— The axes of the planets are inclined to the planes of their orbits. The angle or amount of inclina- tion is not the same for all the planets. Each has its own. But it is important to observe that the angle of inclination of each jilanet undergoes no change. It is said to be "constant." And again the axis of each jilanet preserves invarialily the same direction at every point of the orbit ; in other words, at any two jioints of the orbit the axis is ]iar- allel to itself. The facts that the planetary axes are inclined at constant angles, and preserve unchanging directions, bring about, in combination witli the revolution of the planets, two results : (1) changes of seasons ; (2) variations in the duration of day and night. SEASON'S. — An inspection of the cut opposite will show that as eacli planet passes round the sun, the upper portion of its surface will be directed toward tlie sun at one part of its orbit, the lower at the opposite part. In other words, the northern hemisiihere of each planet will receive the more direct rays of the sun at one time, the southern at another. A hot season, or sum- mer, will therefore alternate with a cold season or i winter. Tlie EartVs Axis is inclined to the plane of its orbit at the constant angle of about 23^°. This inclination, combined with the earth's orbital mo- tion, makes o?i.—Vydtih- quakes may b^ momentary ; or they may consist of several successive shocks; and these may l)e repeated during long periods. After the earth- quake, which, in 1760, destroyed the city of Cu- mana, in Venezuela, shocks were felt nearly everj' hour for fourteen months. In St. Thomas, after the eartlupiake of 1807, and at Charleston, after that of 1880, shocks were felt for many weeks. 3. Area of Disturba/nce. — The area through which the disturbance extends may be very large. The shock of the earthquake of Lis- bon, in 1755, was definitely felt as far as Finland in one direction, and as far as Madeira in another. [See map, page 19.] The disturbance affected the sea to a much greater distance. The water rose among the West India Islands so that Antigua, Martinique, Guade- loupe and Barbadoes were overflowed. The area disturbed was four times as great as that of Europe. In 1783. all the towns witliin a radius of twenty miles from the town of Oppido, in Calabria, were destroyed. The great earthquake of Guadeloupe, in 1842, extentled through the distance of 3,000 miles in a direet line, and S(ai- sibly afiected an area of not less than 3,000,000 square miles. Ix SHAPE, the area of disturbance is commonly an irregulitr oval. 4. The Sea- Wares which are caused by earthquakes that have their centre under the ocean bed, are appalling phenomena. The water at first recedes from the beach, and exposes the sea-bed even beyond the usual limits of low water. Then the sea-wave comes in with a steej) front or wall sometimes more than fifty feet high. It drives back the i-eceding water, and deluges the shore, sometimes demolishing whole towns. It often passes inland to the dis- tance of several miles. The inhabitants rush to the hills, and remain there until the wave sub- sides. Examples. — The great wave of the Lisbon earthtjiiake was sixty feet high at Cadiz. It rose anil fell eighteen times at Tangier, in Africa. In 1854, when Simoda, in Japan, was destroyed by an earthquake, the sea-wave completely overwhelmed the place. The receding wave actually crossed the Pacific, and made the water rise on the coast of California. In 1746, the town of old Calliio. in Peru, was destroyed by an earthquake. A wave 80 feet high tore from her anchors a Spanish man-of-war, lifted her over the houses, and carried her several miles inland. The receding wave left her high and dry on the road to Lima. Sea-waves are often perceptible throughout an entire ocean basin. They travel across the Pacific at the rate of about 850 miles an hour. EARTHQUAKES. If tho cpntre of the earthquake is on land, so near the coast as to disturb tlie sea, the waves produced are thrown out from tlio slioro and are harmless, 'I'his explains why, although the Charleston earthquake was felt at sea as far as the Bermudas, no wave-damage was done in the harbor of Charleston. 5. Destructive Effects. — Earthquakes are perhaps the most impressive manifestations of power in the material world. Tlie destructioji of human life occasioned by them is appalling. On the 1st of November, 1755, Lisbon was shaken by the "great eaj'thquake, " and in six min- utes its palaces were in ruins, and GO, 000 of its inhabitants were dead. In March, ]81;i, Caracas, in Venezuela, was de- stroyed, with 10,000 of its inliabitants. e of tho Orinoco on the north; it thus connects these two river- basins by a water-way that permits the Indians to pass in their canoes from either of the two great rivers into the other. Furthermore, in tlie Brazilian province of MattoGrosso there are two springs side by side, and within a few feet of each other. Prom one (he water flows into the Amazon, from the other into the La Plata ; and so close are the nav- igable waters of these rivers to each other, that, with a sin- gle portage of a few miles, the voyager, as- cending the La Plata from the sea. may re- turn to the ocean again, either through the Amazon or the Orinoco. (^ Europe. shown by those of the New 1. Europe, like North America and South America, has its primary and secondary high- lands and its low plain ; but the ar- rangement of these features is different from that which jirevails in the New World. Two ob- vious differences jiresent themselves : (1) the main axis of elevation extends cast and west, not like the Andes and Eocky Mountains, north and south ; (2) the mountain chains have not tne same well-marked parallelism as is World. 2. The Primary HigJdand of Europe stretches all through the southern portion of the continent, from the Atlantic to the Black Sea, and we may say, regarding the Caucasus as its eastern prolongation, that it reaches the shores of the Caspian. Beginning with the Pyrenees, as its western ter- mination, it culminates in the Alps. Eastwiird of the Aljis it throws out two important branches, the Carjmthians to the north, and the Balkans to the RELIEF FORMS OF THE CONTINENTS. 33 Alps south. These, with the Dinarie Alps, enclose the basin of the Danube. Tn addition to these ranges the Apennines of Italy and the mountains of Greece are included as parts of the j)rimary system. The Alps arc the most celebrated of all the mountain-systems in the world. Their historic and poetical associations ; the grandeur and beauty of their varied scenery ; the number and ex- tent of their glaciers, and their accessibil- ity to travellers, invest them with an interest unrivalled by the loftiest summits of other lauds. Occu^ning a central position between France and Germany on the north, and Italy on the south, they can be reached in a few hours from any of the great cities of Europe. Ownng to their varied attractions they are visited by so many thousands annually, that they have been called, not inappro- priately, " the play-ground of Europe." Plain SECTION OF EUKOI'E FROM NORTU TO SOUTU. -* Jt O C IS Now and then a muttering Jike distant thunder may be caught, as some loosened mass of snow or ice falls with a crash into the valleys ; or the wind brings up from IjcIow in fitfid gusts the murmur of the streams whicli wander down the distant valleys." The highest ])eaks of the Alpine system are Mont Blanc, 15,781 feet, Monte Rosa, 15,220 feet, and the Matterhorn, 11,780. The Ali)s are destitute of ac- tive volcanoes. The-/'yreMec.s present a much greater uni- formity of ar- rangement than the Aljis. Their average height (8,000 feet) is not greatly inferior to that of the Alps (8,000 to 9,000 feet) ; but their highest peak. Mount Maladetta, 11,1G7 feet, is far below the towering masses of Mont Blanc and ]Monte Rosa. The passes of the Pyrenees, however, are higher and less practicable than those of the Alps. The Caiyatl'ians separate the plains of Hun- gary from the great low plain of the continent. Their greatest As we climh iJie Alps, says a distinguished scientific writer, "peali rises behind pealv, crest above crest, with infinite variety of outline, and with a wild grandeur which often suggests the tossing and foaming breakers of a stormy ocean. Over all the scene, if the air be calm, there broods a stillness which makes the majesty of the mountains yet more impressive. No hum of bcc or twitter of bird is heard so high. No brook or waterfall exists amid those snowy heights. The usual sounds of the lower ground have ceased. elevation is about 9,000 feet. The Caucasus range stretches from the Sea of Azov to the Caspian. Two of its peaks. Mount Elburz, 18,572 feet, and Kasbek, 16,545, surpass in height the lof- tiest summits of the Alps. Peninsulas. — High Europe throws out three mountainous projections to- w'ards the south: the Iberian or Sjjanish Penin- sula on the west, the Italian in the centre, and the Grecian on the east. The Iberian or Spanish Peninsula is a great plateau sur- mounted by several parallel ranges. The Pyrenees, which are the principal of these, form the di\-iding line between France and Spain. In the Italian Penijisula we find the Apennines, an im- portant prolongation of the Alpine system. These arc more 34 RELIEF FORMS OF THE CONTINENTS. famed for their beauty than for their altitude. The volca- noes of Vesuvius, Etna, and tiie Lijiari Islands, are consid- ered as belonging to this cliain. The Grecian Penin.iula,\\kii the Italian, boasts of no very clevatx-'d ranges. Its mountains are famed less for their height than for their historic and poetic associations. They were the mythic homes of the gods of aneic.'nt Greece. Tlie tlirone of Jupiter rested on Mount Olympus. The Balkans are the most imjiortant lange. They have an average ele- vation of about 5,000 feet. ^ .5. The Secondary Highlauds comprise the ranges of Scandinavia and the Ural mountains, together with others of less importance. CLlMBINa THE ALPS. The Scandinavian mountains consist, for the most part, of a broad elevated region, intersected by deep and gloomy valleys. Some of these "fiords," as they arc called, are thousands of feet in depth, and penetrate far into the country. One of them is 100 miles in length. The Ural mountains form a natural boundary between Europe and Asia. They extend south- ward, 1,200 miles, from the Arctic Ocean nearly to the Caspian Sea. 4. Loiv Europe consists of a vast plain lying northeast of the primary liighland. It is bordered on the northwest by the mountains of Scandinavia, and on the northeast by the Ui'al range. It ex- tends from the Arctic Ocean to the Black Sea, and westward as far as the Bay of Biscay. The Valdai Hills, near the centre of the plain, mark the highest point of a swell which separates the rivers flowing into the Baltic and White Seas from those which enter the Black and the Caspian. ^ A ^ Asia. 1. Asia, like Europe, may be divided into two grand sections. High Asia and Low Asia. As in the case of Europe, the highlands lie to the south ; the great low region to the north. 2. The Primary HiyJilaud of the con- tinent consists of two portions: (1) the various mountain chains which radiate from the central elevated region knomi as the Plateau of Pamir ; and (2), the Plateau of Tliibet. The Pamir is called by the Asiatics the "roof of the world." In shape it may be regarded as an irregular square. From three of its corners gi'cat chains project. The southeast corner is the start- ing point of the great ridges of the Himalaya, the Karakorum, and Kuenlun. From tlie northeast- ern comer the Thian §han range takes its origin. From the southwestern starts the line of the Hin- doo Koosh. The Plateau of TJiiiet lies between the Him- alayas on the south, and the Kuenlun mountains on the north. It is the loftiest table-land in the world, having an extreme elevation of about 15,000 feet. The Himalayan Range stretches eastward from the Pamir in an unbroken course, for a dis- tance of 1,500 miles. Its breadth varies from 150 to 350 miles, and its mean height has been estimated at 6,000 feet higher than that of the Andes. Over forty of its peaks rise to an altitude of 23,000 feet, and more than 120 reach 20,000 feet. Mount Everest, with an elevation of 29,000 feet, is, so far as known, the highest mountain on the globe. The Himalayas present the grandest possible moimtain scenery: deep gorges wrapt in perpetual twilight gloom, frightful precipices ; sombre forests of rhododendrons and RELIEF FORMS OF THE CONTINENTS. 35 pine trees ; higher up, vast glaciers filling the ravines, and ice and snow covering the ridges which rise one above an- other to such sublime heights as must ever secure tlieir sum- mits immaculate from the footsteps of man. Everything is colossal; but the Himalayas lack the smiling valleys and sheltered lakes which impart such picturcsiiuc charm to the Alj)s. They possess the grandeur without the amenity, the magnificence with- out the variety, which mark the less elevated European system. The Passes of the Himalayas, instead of leading through "low gaps and over gentle declivities, rise up into the regions of perpetual snow and ice, and are so difficult as to be of little avail for the purposes of commerce between the people on tlie opposite sides. They are on an average 10,000 feet higher than those of the Alps, and nearly 4,000 feet higher than those of the Andes. We cannot be surprised that In- dia and Siberia are practically farther removed from each other than if they were separated by an ocean, nor even tliat the o]ipo!>ite slopes of the Himalayas are occupied by men of different races. The Karal-orum range travorsos the plateau of The Kuenlun range separates Thibet and East- ern Turkestan, and is prolonged by the Chinese range of tlie Peling mountains. Tiic Thian Shan range form.s the northern boundary of tlie platean of Eastern Turkestan. Some of its peaks attain the height of 20,000 feet. Siberian Plain SECTION OF ASIA FROM NORTH TO SOUTH. The Hindoo Koosh extends in broad, massive ranges westward for 400 or 500 miles. A depression then occurs. The range, however, is really con- tinued in the Elburz mountain.?, wliich form the northern boundarj' of Persia. The general direction of the great mountain chains of the primary highland region is east and west. 3. The Srroudary Highlamls comprise the Altai moun- Thibct, and is believed to have a greater average lieight than even the Himalayas. It contains Dapsang mountain (height, 28,300 feet), believed to be the liighcst summit next to Mount Everest in the world. tains and their northern con- tinuations, to- gether with tho Great Khingan range, and the ranges of south- eastern Asia, and, finally, the subordinate plateaus of the continent. The Altai mountains ex- tend in a north- easterly direc- tion, and termi- nate inthe Yab- jonoi and Stan- ovoi ranges. They separate the desert wastes of Mon- golia from the plains of Sibe- ria. Some of their peaks are 1 2,000 feethigh. The Oriat Kliingan mountains, with their southern ofEshoots, form the eastern barrier of the great Desert of Gobi. Plateaus are a prominent feature of the Asiatic continent. A series of them extends from 36 RELIEF FORMS OF THE CONTINENTS. the shores of the Eed Sea nearly to the Pacific Ocean. In general they are arid and rainless, sandy, stony, and barren. In the spring the sur- face is thinly sprinkled here and there with grass and herbs, but in the summer and autumn it is, for the most part, dry and slerile. The sheltered valleys are, however, in many cases exceedingly fertile. In such valleys there is a set- tled population, but outside of them the jjlateau region may be described as the home of roving herdsmen and marauding Bedouin. North of the Kuenhin mountains are two plateaus, Eastern Turkestan and the Desert of Gobi. These arc shut in on the north by the Thian Shan and Altai mountains. The average elevation of Eastern Turkestan is about 2,000 feet above the sea-level ; that of Gobi about 4,000 feet. Should we enter Gobi from Thibet, we should make a descent of nearly 9,0C0 feet. The triangular plateau of the Deccan in India rises to the average height of about 3,000 feet. The sides of the triangle are the Eastern Ghauts, the Western Ghauts, and on the north the Vindhya mountains. The plateau of Iran or Persia, including large portions of Afghanistan and Beloochistan, is shut in by the Elburz and Hindoo Koosh moiuitains on the north, by the Zagros chain on the south, and the Suleiman on the east. It rises from 3,000 to 4,000 feet above the sea-level. The plateau of Armenia, with. Ararat (about 17,000 feet liigh) for its culminating point, rises to the westward of Persia. The [ilateau of Asia Jlinor lies westward of that of Ar- menia. It has an average elevation of 2,500 feet. The Taurus ranges bound it on the south. extends through Europe and Asia, from the shores of llie North Sea to Uehring Strait, a distance of more than .5,000 miles. The Kirghiz Stepjjes are wide and monotonous tracts, covered in spring with rough grass, desert in summer, and bleak and desolate in winter. The Silerian Flain consists of prairies, wood- lands and tundras. The prairies and piny forests are in the southern portions, the swampy tundras on the northern edges. Inferior in size to the Siberian Plain, but vastly more imjjortant for their influence upon the his- tory of the human race, are the plains of China and India. They snpjwrt nearly one-half tlie popula- tion of the globe. A remarkable depression is found on this conti- nent. It is occupied by the Dead Sea, the surface of which is 1,300 feet below the level of the ocean. Africa. V^ 1. The Continent of Africa obeys quite close- ly the general law of continental structure. It has mountain ranges along the coast, while a plateau region of less elevation occupies the interior. 2. The Primal'!/ Hif/hland is in the east. It consists of an elevated region which ex- tends all the way from the Isthmus of Suez to the Cape of Good Hope. One important portion of it, DESERT OP SAHARA. The plateau of Arabia forms the southwestern projection of the continent. 4. The Great Loivland of the Asiatic con- tinent lies to the north. It extends from the shores of the Arctic Ocean southward to the base of the Altai mountains and the adjacent ranges, and com- prises the Kirghiz Steppes and the Siberian Plain. It is a part of the almost continuous depression which the plateau of Abyssinia, attains an elevation of 7,000 to 8,000 feet. The culminating jjoints, however, are the snowy heights of Kenia and Kili- ma-lSTjaro (about 19,000 feet high), among the Mountains of the Moon. South of these elevations occur the Livingstone mountains, walling in lake Nyaesa ; and nearly at the southern extremity of the continent lie the Snow mountains, which may RELIEF FORMS OF THE CONTINENTS. 37 be considered as vast terraces ascending from the sea toward the interior. 3, TIte Secondary Hiffh- hnuls include the ranges which border tlie northern and westei'n coasts. The Atlas mountains on the north consist of three or four parallel ranges which ascend from the Mediterranean stage by stage, and increase in height to the westward. The Kong and Cameroons mountains are the principal ranges on the west. The latter are volcanic. They attain at some points the height of 1-3,000 feet. 4. The Inferior of the con- tinent may be regarded as a vast plateau bordered by the various coast ranges. Low plains are to be found only along the coast. The plateau region may be divided into two sections : (1) that portion which consists of prairies and fertile river basins ; and (3) the arid Sahara. The Sahara is considered to have formed, in an older period of the world's his- tory, a portion of the bottom of the sea. It is not an absolute level. Its average elevation is about 1,200 feet, but it contains areas which are 4,000 or 5,000 feet in height, and has a mountain which are below the sea-level. They are marshy regions known as the chottes (.s/iofs). the "'^::^ — r^ The surface of the desert consists, in some places, of sharp stones, in others of gravel, in others again of loose, shifting sand. This last is driven before the winds, and arranged in long lines like billows of the sea. Australia. AUSTRALIA range one of whose peaks is nearly 8,000 feet high. Southward of Tunis are found depressions J. Australia resembles Africa in conforming to the general law of continental relief. It has an elevated border and a depressed interior. The Primary Highland lies along the eastern and southeastern shores. It culminates in the Australian Alps, the loftiest peaks of which are about 7,000 feet high, and terminates in York Peninsula. The Secondary Highland, border- ing the western and northwestern edges of the continent, has an average elevation of 2,000 to 3,000 feet. Of the Central Lowland only small portions, such as the basins of the Darling and Murray rivers, are well known. Large areas are believed to be desert. A character- istic feature of the lowland is its inland salt lakes, several of which are more than 100 miles in length. 38 ISLANDS. TOPICAL ANALYSIS. III. BELIEI'' KORMS OK THE CONTI.VENTS. General Features of Continental Relief. Looiliou of axial line. Central depressions. North America. 1. (lent rat Features. 2. Pacific IRglilaiul. Description. Rocky mountain system. Sierra Nevada and Cascade mountains. Coast range. 3. The Stscondaify U'lijldand. Description. "Tide- water" region. 4. Central Segioii. Description. Ueight of land. South America. 1. General Features. 2. Primary tRghland. Location. The Andes. Re- markable features. Elevation. 3. .Secotidanj ITtghlands. Brazilian Highland. Quiana Highland. 4. Central Heg'mii. Consists of what f Europe. 1. General Features, as compared with those of the American continents. 8. Tlie Primary IRgMand. Location. Principal ranges. The Alps. Circumstances which make them celebrated. The Pyrenees. Carpathians. Cimcasus range. Peninsulas ; Iberian, Italian and Grecian. 3. Secondary Hlghtauds. Scandinavian mountains. Ural. 4. Low Europe. Asia. 1. General Features. a. Tlie Piimary TRghland. Divisions. Plateau of Thibet. Himalayan range. Grandeur of its scen- ery. Passes. Karakorum. Euenlun. Thian Shan, and Hindoo Koosh ranges. 3- Secondary J/lgfdaiids. Consist of what ? Plateaus of Asia, extent and barrenness of. Eastern Tur- kestan. Desert of Gobi. Deccan. Iran. Armenia. Asia Minor. Arabia. 4. TTie Great Lowland. Location. Kirghiz Steppes. The Siberian plain. Plains of China and India. Dead Sea region. Africa. 1. Corre.y)ondence to the general law. 2. Primary Ifighland. Location. Extent. 3. Secondary Highlands, include what ? 4. The interior. Divisions. The Sahara. Australia. 1. Conformity to the general law. Pri?nary inghland. Secondary Highland. Central Lowland. Test Questions. -Considering Europe and Asia as one continent, where would be the central depression ? Do you know anything re- mnrkable about it ? V IV. ISLANDS. 1. Classificatiott.—A portion of the dry land consists of islands. These are divided into two general classes, continental and oceanic islands. 2. Continental Islands, as the name im- plies, are situated near the continents, and in earlier periods of the world's history many of tlicm doubtless actually formed parts of the continents. This conclusion is based upon the resemblances that exist between the islands and continents in their rocks and soils, and in their vegetable and animal productions. Prom the fact, for example, that in past geological peri- ods the same animals lived in Great Britain as in Europe, geologisis are convinced that Great Britain and the adja- cent islands were originally connected with the European continent. Continental islands are usually arranged either in a line parallel to the coast of the continent, or upon a line which may be fairly regarded as a continuation of the continental coast line. The Japanese Islands illustrate well the parallel ar- rangement ; the "West Indies and Sunda Islands are arranged upon lines which may properly be re- garded as jirolongations of the eastern shores of North America and Asia respectively. [See map, p. 24] 3. Oceanic Jslands are situated in mid- ocean, far away from the continents. They are arranged sometimes in lines, sometimes in groups of irregular shape. They are strikingly unlike the continental islands. These latter are made up of the same I'ocks as the continents. The oceanic islands are not. They are composed either of vol- canic products or of coral. In regard to forma- tion, oceanic islands are, therefore, of two kinds, volcanic and coral. 4. Volcanic Islands are arranged, as a rule, along the gi-eat bands or belts of volcanic ac- tivity which traverse the globe. Most of them are found within the volcanic belts of the Pacific and the Atlantic. [See jx 18.] There are, however, exceptions to this general rule, many volcanic islands being situated qtiitc irregu- larly. It is curious that the volcanoes upon islands in the Pacific belt are among the most active in the world ; those in the Athmtic belt are either ex- tinct, or are bordering on extinction. Formation. — Volcanic islands are formed by the accumulation of materials thrown out by sub- marine volcanoes. Sometimes such islands are formed very suddenly, as in the case of Graham Island, in 1831, and of one off the Island of San- torini, in the Mediterranean, in 1866. [See p. 15.] In elevation above the sea-level, volcanic islands, owing to the method of their formation, are natu- rally far higher than those of coral origin. Some, like the Sandwich Islands, attain an altitude of many thousand feet. ISLANDS. 39 5. Coral Islands, — Multi- tudes of islands are mainly com- posed of coral, and liencc are called coral islands. They are formed chiefly by the agency of the coral imJijp, Ijiit partly by the action of tiie waves. The Coral Polyp. — The polj^is themselves must first be described, before we can rightly appreciate tlieir work. There are many differ- ent species, but we need to concern ourselves only about the reef-build- ing polyps. Of these there are va- rious kinds. The cut represents a piece of coral crowned with a colony of tiny laborers. Description. — The numerous rays which project from the polyps are called tentacles. They are so many little fans which the polyp moves, so as to draw a current of water towards his mouth. The mouth is represented in the cut by a slit in the cen- tre of the rays. The body of each polyp is in a little pocket, or hole, in the sub- stance of the coral. It consists of an outer sack containing an inner sack, this latter being the stomach. In the open space be- tween these two, the bony part of the skel- eton of the polyp is formed. It is lime- stone, and is separated by the polyp from the sea-water which is continuously sup- plied by the movements of the tentacles. Then again, although we may consider each polyp as an individual, like a single bee or ant, it is to be observed that the members of such a colony as is shown' in the cut are not altogether independent. A common fleshy substance extends from one to the other, and thisacts as the individual polyps do. Like them it separates limestone from the sea- water, and makes out of it a sort of common skeleton. With i'uLYPs EUXLUiNG CORAL— {natural size). endures for ages. As rapidly as individuals die, others take their place. Young polyps actually shoot like buds out of the substance of the older ones, and, besides this, addi- tional multitudes are hatched from eggs. One vast host of workers then deposits its layer of limestone, and passes out of existence. Another and another succeeds, and thus coral grows and rocky columns rise through the waves to become the supports of coral islands. CORAL REEFS OFF TUE NORTH FHORE OF TAHITI. this the skeletons of all the polyps are united so that thoy form one dense rock-like mass. This substance is known as coral. The life of the individual poh^p is brief, but the colony "Work of the Polyp. — Let \ts now consider what we may term the life-work of the polyj). It consists in the building of reefs. Coral reefs may be classed as (1) fringing reefs; (2) barrier reefs; (.3) atolls. Fringing reefs are bands of coral rising a few feet above the water, and surrounding islands or .skirting the shores of continents. The bil- lows dash themselves into spray on these reefs, but leave the water on the inside as smooth as a mill-pond. Barrier reefs are the same as fringing reefs, only that they are further removed from the land. Some of them are only a few miles in circumference, others are several hundred. / 40 ISLANDS. WHITSUNDAY ISLAND. The great barrier reef of Australia is 1,200 mUes long. The island of New Caledonia and many others are protected from the sea by similar reefs. An atoll is a reef from witliin which an ishind, once encircled, has disappeared. It consists, there- fore, of a belt or strip of coral enclosing an ex- panse of water. The water thus enclosed is called a lagoon. Atolls are usually nearly oval or circular, but in many cases they are quite irregular in shape. Sometimes, as in the case of Wliitsunday Island, they are complete rings ; but most frequently, on liED (JOKAL. the side not exposed to the prevailing winds, there are one or more breaks. The atolls are almost innumerable. There are nearly a hundred of them in the Dangerous Archipelago, which lies to the westward of Taliiti. They are not more than half a mUe across, from the sea to the lagoon. In their highest parts they are only a few feet above the water; still they re- sist the utmost fury of the waves. They are thickly covered with vegetation. Work of the Waves. — When the polj-ps have reared their wondrous structure up to the IcA'el of low water, they have finished their part in the formation of the coral island. Now follows the work of the waves. They break 'oil portions of the coral growth. The}^ next sweep these portions into a ridge, just as the sand is swept up on the sea-shore. The ridge, heaped up by successive additions of broken coral, finally becomes so high that it overtops the waves, and an island is formed. The next stage is the appearance of vegetable life. Floating wood lodges among the coral fragments. It decays and forms mould. Seeds, such as cocoa- nuts, not injured b}' salt water, are wafted to the new-born islet ; others may be carried thither by birds. Under the stimulus of a tropical sun they grow, and in process of time deck the dead coral mass with living green. The bread-fruit and cocoa-palm are the most important of the forms of plant-life that flourish upon the coral islands. No large animals live upon them, and of course neither metals nor coal are found on them. They are not fitted to be the abode of human beings at all advanced in the scale of civilization. G. ''Coral Groves" and Coral Seas. — So singularly transparent is the water enclosed by the atolls, that the ship, as she lies at her an- chor, appears rather to be suspended over the bot- tom than to be resting on the deep. I have seen plainly coral-trees, standing in groves at the depth of one hundred feet. The coral groves of the ocean floor are decorated like the gardens of the land, the flower-like polyps answering to our pinks and daisies, violets, and lilies. Some of them are of the brightest and softest tints, pink, pearl color, and bine, green, purple and yellow. They strew the bottom, which is ISLANDS. 41 of the whitest and purest sand; or Iiang like leaves and flowers, or elingf like mosses and liebons to the branching coral, and lend rare enchantment to the scene. Fishes of many colors, with exquisite grace of movement, dart among the branches. They are as multitudinous as bees over the flower-beds, and, with their polished scales, vie in brilliancy with the featheri'd tribes of the land. To look down upon such a scene in the great bosom of the ocean is like gazing U])on t\w splendors of fairyland itself. The full beauty of the coral groves, however, cannot be seen from above. Their admirer must dive to th(^ liottoin. Yet not without risk does he venture. The fire coral (Mil- lepora). and the MeduScB swimming amid the treasures of the deep, sting, when touched, like the worst of nettles. Black sea urchins drive their long barbed stings into the flesh of the foot, where they break off and remain, inflicting painful and dangerous wounds. But the worst of all injuries to the skin are inflicted by the coral rocks themselves, owing to their myriads of hard points and sharp jagged edges. 7. DistHbution of i'oriih — The reef- building polyps are confined to tropical waters. The central part of the Pacific Ocean is the scene of their greatest activity. They are also found in many portions of the Indian Ocean, in the Red Sea and the Persian Gulf. E.xcept in the region of the West Indies, at the Bermudas, and off the coast of Brazil, there are none in the Atlantic. The area within which tliey are at vvorl; is not less than 25 millions of square miles. H. Oi'igin of Atoll a.— Many of the reefs and atolls rise from very great depths ; but the polyps are most vigorous in water not deeper than sixty feet ; and in water that is more than 180 feet deep they cease to live. The question, therefore, arises, how can the foundations have been laid for certain reefs and atolls, which are known to stand in water not less than a mile and a half deep ? This was a question that long puzzled Physical Geographers. Finally, Darwin suggested an an- swer. It enables us to understand not alone how atolls in deep water may have originated ; but also how atolls in general were formed. It is well known to geologists that the level of the ocean bed is subject to change. It may be up- heaved, or, again, it may subside. Darwin con- jectured that as fast as the coral reef, ages ago, was being built up toward the surface, it was car- ried down by the subsidence of the ocean bed. ExPLANATioif. — Let us notice the successive steps of this process. There is reason to believe that in those parts of the ocean where atolls now abound, high mountains once towered. These mountains were islands. The polyps built encir- Dling reefs around them. But in many cases, as they built up, a gradual subsidence took place, until the island itself disap- peared beneath the waves. Tliis subsidence on the one hand, and this I)uildiiig up on the other, may have continued for ages, and to tlic extent of thou- sands of feet, so that where the mountain then was, may be now deep waters and low atolls. Thus (L) Section ot mouulain rising ahove water. (K It) Sections of fringing reef resting on slopes. .. (L) Section of same mountain sulimergcd : (R R) Sections of same fringing reef become an atoll. the mountain-top was replaced by the lagoon, and the encircling reef became the atoll. Tahiti affords an illustration of this process. It is a vol- canic island with a fringing reef, the foundations of which rest upon the submarine slopes of the island. It exhibits the appearance which must have been presented by existing atolls before the subsidence of the ocean floor had carried down beneath the surface of the sea the mountainous islands formerly enclosed by them. TOPICAL ANALYSIS. IV. ISLAXDS. 1. Classification. 2. Continental Islands. Situation, fliLiracter. 3. Oceanic Islands. How distinguished from continental. 4. Volcanic Islands. Location. Formation. Elevation. 5. Coral Islands. How fonncrt. The coral polyp. Dc-scription. Work. Coral reefs. Kinds. Alolls. Work uf the waves. Origin of vegetation. Characteristic animal and vegetable life. Minerals. 6. Coral Groves and Coral Seas. Clearness of. Beauty of. 7. Distribution of Coral. 8. Origin of Atolls. ' Difficulty connected with. Depth at which the coral polyp can work. Darwin's theory. Illustration in Tahiti. Test Questions. — Would you consider a coral island a desirable place of residence ? Why ? 42 TOPICAL ANALYSIS FOR REVIEW. TOPICAL ANALYSIS FOR REVIEW. Arrangement of Land Masses. . Itelations of air, wator ami land to cai-li otlier. Extent and distribution of the land and shape of the continents. Northern and Southern Hemispheres compared as to extent. As to progress. Land and Water Hemispheres. Forms of Land Horizontal Forms. Vertical Forms Lowlands. Plains. Various kinds. [^ Highlands. f Plateaus. Mountains. Fonnation of. Valleys. Kinds. How formed. L Causes and effects of relief. r General features of continental relief. I North America. South America. Resemblance to North America. Relief Forms of the Continents. < Europe, general description. Alps. Peninsulas of High Euroije. Asia. Africa. The Sahara. ^ Australia. f ContinentaL Islands. f Volcania Oceanic . (^ Coral. C Coral Polyp. Coral Reefs. Classes of. Development of the reef into an island. I Distribution of Coral. ' Origin of Atolls. ?^ PART III. THE WATEK. I. PROPERTIES OF WATER. 1. Composition.— Tm-ning from the liind we come now to the consideration of the water. Its offices are of tlie highest interest and impor- tance. Pure water is composed of two gases, hydrogen and o.xygen, united in tlic proportion of two vol- umes of hydrogen to one of oxygen. ii. l*hifttical I*)'ojte)'ties of loafer. — Tlie properties of water that specially interest the Physical Geographer are the following : (1) water changes its forms with remarkable readiness ; (2) it expands when passing into the solid state ; (3) it has extraordinary capacity for heat ; (4) it lias great solvent power. Forms of Wateu. — The three forms of water are the liquid, solid, and gaseoTis. Changes of temperature that are of common occurrence cause it to pass from one to another of these. Now it becomes a solid. Falling gently as snow, it muffles up the young plants as with a mantle, screening them from the biting winds of winter ; as ice, it covers the sui-face of the lakes and the rivers, and protects the denizens of the water, as snow does the insects and tender plants of the land. Now it becomes a gas, and carries off water from the sea to supply the springs among the moun- tains that give drink to man and beast ; or, man- tling the earth with an invisible screen, prevents the too rapid escape of its warmth at one time ; or, assuming the form of clouds in the sky, shields it from the too great heat of the sun at another. Having fulflllcd these duties, it turns again into beauti- ful, (lancing, laughing water. Enduring as the mountains, it is one of the few visible things on earth upon which time, since the world began, has wrought no marring change. Friction abrades it not, nor have all the keels that have ploughed the ocean wasted so much as one single drop of it. There it is. pure and bright, just as it came from the hands of its Maker; its power is imimpaired and always fresh; it is ever busy and never weary. E.\p.\.NSiON OF Watek. — Water expands when passing from the liquid state to the solid. This is probably due to the fact that its ])articles, when crystallized, require more space than l)efore. When cooled, it follows the general law, and contracts un- til it reaches the temi)erature of 39J° Fahr Be- low this it disobeys the general law, and expands till it reaches 32' Fahr., its freezing point. Then suddenly it hardens into ice, and attains its maxi- mum cx])imsion. Because ice is more exjjanded than water, it is lighter titan water, and, as we all know, it floats. The law by which ice floats is one of the beautiful and benign jirovisions of nature. Were ice heavier than water, it would sink as fast as it was formed, and our river-channels and shallow lakes would be filled with solid ice from the bottom to the top. Expansive Force. — Another important conse quence of the expansion of water lolien freezing is that it exerts a force that is jjracticallg irresistible. It sunders the solid rock from the foundations of the mountains, and crumbles it into fragments. One of the most interesting effects of the force exerted by freezing water occurred in Norway in 1717. The snow covering a rocky region had rapidly thawed, and filled the crevices of an enormous mass of rock with water. Suddenly the weather changed. The water enclosed in the crevices of the rock was frozen. Expansion occurred, and a mass of rock was rent away and precipitated into the neighboring fiord. The waters of this being suddenly driven from their channel engulfed a household, and submerged the adjoining fields. KFFECTS OP KXl'ANSIUN rKODUt El) BV THE FREEZING OP WATER. Two bombs having been filled with water, and the fusee holes firmly closed with an iron stopper, were exposed to intense cold ; on freezing, the stopper of one was projected to a distance of more than 150 yards, while the other bomb was split open and a sheet of lee was forced through the crack. 44 PROPERTIES OF WATER. Capacity for Hf:at. — Water, of all hnoivn substances, has iJte greatest ccipacUy fur heat. The heat of bodies exists in two forms ; as sensible heat, or tliat which you cau feel, and insensible, or tliat which you cannot feel. The latter is com- monly called latent, or Iiidden heat. In the process of evaporation a certain quantity of sensible heat is absorbed and rendered latent ; in the op])osite process of condensation a certain amount of latent heat is released and made sen- sible. '• Ciapacityfor heat" means the power possessed by a body of storing away heat, and rendering it latent or unfelt. Explanation. — Suppose you take a cubic foot of ice at 27°, for instance; put it in a vessel and set it over a steady lamp which affords sufficient heat to raise the temperature of the ice 1° a minute. At the end of five minutes the ice would be at 32°. The heat has warmed the ice. It is sensible, that is, you can feel it. The ice will now begin to melt, but noticed, how, as a general rule, the intense cold is mitigated just before a snow-storm. This is due to the condensation of vapor into water, and the freezing of that water into snow. It has been computed that from every cubic foot of vapor condensed, and frozen into snow, heat enough is set free to raise more than 100,000 cubic feet of air from the. temjierature of melting ice to summer heat. Nature makes great use of these counter-proper- ties, the evaporation and condensation of water. She bottles away the heat of the torrid zone in little vesicles of vapor, thus cooling the atmos- phere. She then delivers these vesicles to the winds to be by them transported to other regions. There they are condensed into rain, and their heat set free to warm the air and modify the climate. [See p. 86.] The Solvent Power of water is another prop- erty of great importance. The forms of plant and animal life are largely built up of materials which enter them in solution. Water acts as a vehicle for conveying these materials into the living system. It is es- sential therefore to the maintenance of the life of the world. CIRCDXATION OF W.\TER. the heat, instead of warming the ice or the water, only melts the ice. At the end of 143 minutes all the ice will be melted; but the temperature of the water will still be 32\ and no more. Now what has become of all the heat received from the lamp during these 143 minutes? It has gone to convert the solid into a fluid, and has been rendered latent ; that is, it has been stowed away and concealed in the water. Now let the lamp burn, as before, with sufficient inten- sity to raise the temperature of the water 1" a minute. In 180 minutes the teinperature will be raised from 33° to 312°, which is the boiling-point; and the water will feel hot. This again is sensible heat. The boiling water, however, now ceases to become hotter, but if you let it stay over the lamp, you will find that, at the end of 967 minutes more, it will have boiled away. Now the vapor thus produced has iden- tically the same temperature as the water, viz., 212°, so that 967' of heat will have been rendered latent. Evaporation exerts a cooling influence. — From the above it is evident that ice or water becoming vapor, absorbs heat, and renders it " latent " or hidden. Condensation of water, on the other hand, exerts a warming injltience. You must have frequently 3. Circulation of Water.— The readiness with which water changes its form and i^asses from the liquid state to that of vapor, and from the vajiorous to the liquid state again, is the means whereby a con- ,^^^ stant circulation is carried on from the sea to the land, and from the land back to the sea again. Let us trace its course. Incessantly the waters of the sea are converted by the sun's heat into invisible vapor. This passes into the air, and the winds transjjort it to the land. Condensed, it falls as rain or snow. It fills the springs and replen- ishes the I'ivers ; it waters the thirsty lands. Por- tions of it find their way back to their home in the sea, through the river channels ; others, evapo- rated, rise on the wings of the wind, and again, being cooled, descend as rain or snow. And thus all the water of the globe comes out of the sea, as from a reservoir, and it all finds its way back there again. TOPICAL ANALYSIS. I. PROPERTIES OF WATER. 1. Composition. 2. Physical Properties. Forms of water. Cause of changes of forms. Uses ill the solid form. In the gaseous form. In- destructible nature of water. WATERS OF THE LAND. 45 j ExpanBion in freezing. Important result. Capacity forlicat. Ilcttt rendered latent in melting. In evaporatidn. Effect oCevaiJoratinn and condensation of water on temperature and clinuite. Sol vent power. 3. Circulation ofWater. The great reservoir. Test Questions.— Name some forms of water remarkal)Ie for tlieir beauty. At wliat temperature is water heaviest ? In the circulation of water between land and sea what force carries the water down to the f^ea ? What force carries it back to the land ? i r II. WATERS OF THE LAND. 1. Spriitf/s. — A jjortion of the rain wliich falls upon the land flows off to the sea through brooks and rivers. The larger part of it, however, does not flow off, but accumulates in swamps and lakes, or enters the ground. The latter portion, sinking into the earth under the influence of gravity, finally encounters layers of rock which it cannot penetrate. It then follows the incline of these layers, and flows for a greater or less distance, until it reaches a point where the land is depressed. Here it finds egress as a surface spring. If the area through which such water percolates be large, and if the slope along which it flows be gentle, then tlie sjjring will be perennial or unfailing. The depth to which percolating water descends is sur- prising. From a deep well sunk in a certain district of Prance, pieces of leaves were thrown up by the first gush of water from a depth of about 400 feet. These leaves were comparatively fresli. They were ascertained to have come from a distance of about 150 miles from the spring. A similar phenomenon has been observed in other places. Prom the percolation of water through the earth arises one of the greatest diificulties in mining operations. Before the invention of steam-pumps many coal pits in England had to be abandoned owing to the fact that, in the expressive language of the miners, they were drowned. water, they crop out upon the surface. Dipping down, however, they arc perhaps 1,000 feet below the surface at the point II. Between tliem is KK, a layer of gravel through which rain water can percolate, but from which it cannot escape, being contliied by AB and CD. Trickling down through KK the water accumulates. The tube of an Arte- sian well, I, sunk tlirough AB, enables it to rise to the height of its distant source. When the source of supply is very much higher than the surface where the well is sunk, the water shoots upward with considerable force. The jet from such a spring near St. Etienne, in France, rises to a height of about 25 feet. The Frencli colonists in Algeria have sunk a number of Artesian wells on the margin of the Great Desert of Sahara, and thus supplied themselves with an abuntiance of water. INTEH.'IIIT lENT ^PltlNU. ARTESIAN WELL. Action of ArtesianWells. — The action of " Artesian wells," so called from Artois in France, where they were first used, very clearly illustrates that of natural springs. Let US suppose that AB and CD, in the illustration, are layers of rock impervious to water, and that at a dist;ance of 500 miles or more from a desert or region ill supplied with Intermittent Springs. — The springs which have excited the greatest curiosity are those which, from their alternate subsidence and flow, are called intermittent. The cause of this peculiarity is illustrated in the accompanying cut, and will be readily understood by any one who has seen a siphon used. The passage from the reservoir to the surface of the ground is curved like a siphon and acts in the same manner. Water percolates through the fissures in the rock and accumulates in the resei-voir. As soon as it rises above the level of the bend of the siphon, h, it begins to flow, and does not cease till it has fallen below the mouth of >- the passage at a. Thus the reservoir alter- nately fills and discharges itself. Thermal or Hot Springs and Geysers have been already discussed. [See p. 14. J It remains to be said that the waters of such springs may be ejected in two ways : (1) in ~^ the manner above indicated, the water seek- T ing the level of its source; or (2) by the force of steam, or gases superheated by the internal heat of the earth. Mineral Springs abound in many parts of the world, chiefly in mountainous and volcanic regions. Their waters are charged with variou.s substances. Iron, salt, sulphur, and carbonic acid are the most common ingredients. 46 WATERS OF THE LAND. 2. Hivers. — Eivers receive their sujiply of water from si)rings, or molting snow-fields and glaciers. From various springs in one vicinity little streamlets pour their contril)utions. Influ- WATEK DOING IT^ WullK - KA \ IN h; UF OCOBA.MBA, enced by gravity these seek the lowest level. They unite and form a river. Again, just as the stream- lets issuing from a number of springs make a river, so a number of rivers, all seeking the chan- nel of greatest dejiression, blend together and make one mighty water-course. Such a water-course, with its tributary streams, is called a river-system. Not unfrequently on the way to the sea a river passes by a very sudden descent from a higher to a lower level. This gives rise to cataracts. According to the violence of the descent they are classed as rapids or waterfalts. When the descent is very abrupt, but still not perpendicular, the term rapids is properly employed. The cataracts of the Nile and the rapids of the St. Lawrence are noted illustra- tions. The term waterfall is used when the water drops per- pendicularly. The loftiest waterfalls arc those of the Vosem- ite in California, 2,500 feet, and the KeeLfoss in Xorway, 2,000 feet high. The grandest of all waterfalls are those of Niagara. Here the water discharged by four of the Great Lakes of North America plunges in a single leap of 100 feet from the terrace of Lake Erie to the lower level of Ontario. Offices of Rivers. — Rivers, viewed as parts of the teiTcstrial machinery, have two main offices : (1) they bring ahout vast changes in the surface of the earth ; (2) they are channels ly which the drainage of the land is accomplished. 3. H