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PORTRAIT. 6 6 ta fof a eA ae cat ‘ Eg fy aye An SRIEXNIEX 7. See paets et (Mie a GA iat ea tt ANGRY PE ges olny eae | Paint " Pp, Oras hry Vaph oe = ate. pre Wit cs PP Wie ena) I Mey epee BOHN'S SCIENTIFIC LIBRARY, HUMBOLDT’S COSMOS. - & 34x10 3 k Fo COSMO S: A SKETCH PHYSICAL DESCRIPTION OF THE*UNIVERSE. RY ALEXANDER VON HUMBOLDT. TRANSLATED FROM THE GERMAN, BY E. G. OTTE. Naturse vero rerum vis atque majestas in omnibus momentis fide caret, si quis modo partes ejus ac non totam complectatur animo.—Plin., Hist. Nat., lib. vii. c. 1, VO F: LONDON: HENRY G, BOHN, YORK STREET, COVENT GARDEN 1849. ‘ / ; a. Yee 9 el 49 1h Lie Milas é re LONDON : PRINTED BY HARRISON AND SON, ST, MARTIN’S LANE. 2 OT eg NEI we rice Bt 5 af SEEM D an oe | | ass ee * 4 bY ite : SEI ihe DATE YY, . ene 7? eee ’ eeee® . ” Ry oe OPE o5i8 TRANSLATOR’S PREFACE. I cANNOT more appropriately introduce the Cosmos to the notice of the readers of the Scientific Library, than by pre- senting them with a brief sketch of the life of its illustrious author.* While the name of Alexander von Humboldt is familiar to every one, few, perhaps, are aware of the peculiar circumstances of his scientific career, and of the extent of his labours in almost every department of physical knowledge. He was born on the 14th of September, 1769, and is, there- fore, now in his 80th year. After going through the ordinary course of education at Géttingen, and haying made a rapid tour through Holland, England, and France, he became a _ pupil of Werner at the mining school of Freyburg, and in his 21st year, published an ‘‘ Essay on the Basalts of the Rhine.” Though he soon became officially connected with the mining corps, he was enabled to continue his excursions in foreign countries, for during the six or seven years succeeding the publication of his first essay, he seems to have visited Austria, Switzerland, Italy, and France. His attention to mining did not, however, prevent him from devoting his attention to other scientific pursuits, amongst which botany and the then recent discovery of galvanism may be especially noticed. Botany, indeed, we know from his own authority, occupied him almost exclusively for some years, but even at this time he was practising the use of those astronomical and physical instruments, which he afterwards turned to so singularly excellent an account. The political disturbances of the civilized world at the close — of the last century prevented our author from carrying out * For the following remarks I am mainly indebted to the articles on the Cosmos in the two leading quarterly Reviews. Vou. I. b vi TRANSLATOR’S PREFACE. various plans of foreign travel which he had contemplated, and detained him an unwilling prisoner in Europe. In the year 1799 he went to Spain, with the hope of entering Africa from Cadiz, but the unexpected patronage which he received at the Court of Madrid, led to a great alteration in his plans, and decided him to proceed directly to the Spanish Posses- sions in America, “and there gratify the longings for foreign adventure, and the scenery of the tropics, which had haunted him from boyhood, but had all along been turned in the dia- metrically opposite direction of Asia.” After encountering various risks of capture, he succeeded in reaching America, and from 1799 to 1804 prosecuted there extensive researches in the physical geography of the New World, which have indelibly stamped his name in the undying records of science. Excepting an excursion to Naples with Gay Lussac and Von Buch in 1805 (the year after his return from America), the succeeding twenty years of his life were spent in Paris, and were almost exclusively employed in editing the results of his American journey. In order to bring these results before the world, in a manner worthy of their importance, he commenced a series of gigantic publications in almost every branch of science, on which he had instituted obser- vations. In 1817, after twelve years of incessant toil, four- fifths were completed, and an ordinary copy of the part then in print, cost considerably more than one hundred pounds sterling. Since that time the publication has gone on more _ slowly, and even now, after the lapse of nearly half a century, - itremains, and probably ever will remain, ‘incomplete. In the year 1828, when the greatest portion of his literary ‘ Jabour had been accomplished, he undertook a scientific journey to Siberia, under the special protection of the Russian Government. In this journey—a journey for which he had prepared himself by a course of study unparallelled in the history of travel—he was accompanied by two companions hardly less distinguished than himself, Ehrenberg and Gustav | TRANSLATOR’S PREFACE. Vil Rose, and the results obtained during their expedition, aré recorded by our author in his Fragments Asiatiques, and in his Asie Centrale, and by Rose in his Rese nach dem Oural. If the Aste Centrale had been his only work, constituting, as it does, an epitome of all the knowledge acquired by himself and by former travellers, on the physical geography of North- ern and Central Asia, that work alone would have sufficed — to form a reputation of the highest order. I proceed to offer a few remarks on the work of which I now present a new translation to the English public, a work intended by its author “to embrace a summary of physical knowledge, as connected with a delineation of the material universe.” The idea of such a physical description of the universe had, it appears, been present to his mind from a very early epoch. It was a work which he felt he must accomplish, and he devoted almost a lifetime to the accumulation of materials for it. For almost half a century it had occupied his thoughts; and at length in the evening of life, he felt himself rich enough in the accumulation of thought, travel, reading, and experimental research, to reduce into form and reality, the undefined vision that has so long floated before him. The work when completed will form three volumes. The first volume comprises a sketch of all that is at present known of the physical phenomena of the universe: the second comprehends two distinct parts, the first of which treats of the incitements to the study of nature, afforded in: descriptive poetry, landscape painting, and the cultivation of exotic plants;/while the second and larger part enters into: _ the consideration of the different epochs in the progress of discovery and of the corresponding stages of advance in: human civilisation. The third volume, the publication of: which, as M. Humboldt himself informs me in a. letter addressed to my learned friend and publisher, Mr. H. G. Bohn,’ “has been somewhat delayed, owing to the aaa state of» b2 yiil TRANSLATOR S PREFACE. public affairs, will comprise the special and scientific develop- ment of the great Picture of Nature.” Each of the three parts of the Cosmos is therefore, to a certain extent, distinct in its object and may be considered complete in _ itself. We cannot better terminate this brief notice, than in the words of one of the most eminent philosophers of our own country, that ‘‘ should the conclusion correspond (as we doubt not) with these beginnings, a work will have been accom- plished, every way worthy of the author’s fame, and a crown- ing laurel added to that wreath, with which Europe will always delight to surround the name of Alexander von Hum- boldt.” In venturing to appear before the English public as the interpreter of “the great work of our age,’* I have been encouraged by the assistance of many kind literary and scien- tific friends, and I gladly avail myself of this opportunity of expressing my deep obligations to Mr. Brooke, Dr. Day, Professor Edward Forbes, Mr. Hind, Mr. Glaisher, Dr. Percy, and Mr. Ronalds, for the valuable aid they have afforded me. It would be scarcely right to conclude these remarks without a reference to the translations that have preceded mine. ‘The translation, executed by Mrs. Sabine, is singularly aecurate and elegant. The other translation is remarkable for the opposite qualities, and may therefore be passed over #ilence. ‘The present volumes differ from those of Mrs. Sabin~ in having all the foreign measures converted into correspond. ing English terms, in being published at considerably less than one third of the price, and in being a translation of the entire work, for I have not conceived myself justified in omitting passages, sometimes amounting to pages, simply because they might be deemed slightly obnoxious to our national prejudices. * The expression applied to the Cosmos, by the learned Bunsen in his late Report on Ethnology, in the Report of the British Association for 1847, p. 265. , AUTHOR’S PREFACE. In the late evening of an active life I offer to the German public a work, whose undefined image has floated before my mind for almost half acentury. Ihave frequently looked upon its completion as impracticable, but as often as I have been disposed to relinquish the undertaking, I have again—although perhaps imprudently—resumed the task. This work I now present to my cotemporaries, with a diffidence inspired by a just mistrust of my own powers, whilst I would willingly for- get that writings long expected are b isha received with less indulgence. Although the outward relations of life, and an irresistible impulse forwards knowledge of various kinds, have led me to occupy myself for many years—and apparently exclusively— with separate branches of science, as, for instance, with descriptive botany, geognosy, chemistry, astronomical deter- minations of position, and terrestrial magnetism, in order that - I might the better prepare myself for the extensive travels in which I was desirous of engaging, the actual object of my studies has nevertheless: been of a higher character. The endeayour to comprehend the phenomena of pial objects in their general connection, and to represent nature as one great whole, moved and animated by internal forces. My inter course with highly gifted men early led me to discover that, without an earnest striving to attain to a knowledge of special branches of study, all attempts to give a grand and general view of the universe would be nothing more than a vain illusion. These special departments in the great domain of x AUTHOR'S PREFACE. natural science are, moreover, capable of being reciprocally fructified by means of the appropriative forces by which they are endowed. Descriptive botany, no longer confined to the narrow circle of the determination of genera and species, leads the observer who traverses distant lands and lofty mountains to the study of the geographical distribution of plants over the earth’s surface, according to distance from the equator and vertical elevation above the sea. It is further necessary to investigate the laws which regulate the differences of temperature and climate, and the meteorological processes of the atmosphere, before we can hope to explain the involved causes of vegetable distribution; and it is thus that the observer who earnestly pursues the path of knowledge is led from one class of phenomena to another, by means of the mutual dependence and connection existing between them. ».I have enjoyed an advantage which few scientific travellers have shared to an equal extent, viz., that of having seen not only littoral districts, such as are alone visited by the majority of those who take part in voyages of circumnavigation, but also those portions of the interior of two vast continents which present the most striking contrasts, manifested in the Alpine tropical landscapes of South America, and the dreary wastes of the steppes in Northern Asia. Travels, undertaken in dis- tricts such as these, could not fail to encourage the natural tendency of my mind towards a generalisation of views, and'to encourage me to attempt, in a special work, to treat of the knowledge which we at present possess, regarding the sidereal and, terrestrial phenomena of the Cosmos in their empirical relations. The hitherto undefined idea of a physical geography has thus, by an extended and perhaps too boldly imagined a plan, been comprehended, under the idea of a physical description of the universe, embracing all created — in the. regions of space and in the earth. The very abundance of the materials which are echiae to the mind for arrangement and definition, necessarily impart ‘AUTHOR’S PREFACE. xi no inconsiderable difficulties in the choice of the form under which such a work must be presented, if it would aspire to the honour of being regarded as a literary composition. Descriptions of nature ought not to be deficient in a tone of life-like truthfulness, whilst the mere enumeration of a series of general results is productive of a no less wearying impres- sion than the elaborate accumulation of the individual data of observation. I scarcely venture to hope that I have succeeded in satisfying these various requirements of compo- sition, or that I have myself avoided the shoals and breakers which I have known how to indicate to others. My faint hope of success rests upon the special indulgence which the German public have bestowed upon a small work bearing the title of Ansichten der Natur, which I published soon after my return from Mexico. This work treats, under general points of view, of separate branches of physical geography, (such as the forms of vegetation, grassy plains, and deserts.) The effect produced by this small volume has doubtlessly been more powerfully manifested in the influence it has exercised ‘on the sensitive minds of the young, whose imaginative facul- ties are so strongly manifested, than by means of anything which it could itself impart. In the work on the Cosmos on which I am now engaged, I have endeavoured to show, as in that intitled Ansichten der Natur, that a certain degree of scientific completeness in the treatment of individual facts, is not wholly incompatible with a picturesque animation of style. - Since public lectures seemed to me to present an easy and efficient means of testing the more or less successful manner of connecting together the detached branches of any one science, T undertook, for many months consecutively, first in the French language, at Paris, and afterwards in my own native German, at Berlin, (almost simultaneously at two different places of assembly,) to deliver a course of lectures on the physical description of the universe, according to my conception xi ' AUTHOR’S PREFACE. of the science. My lectures were given extemporaneously, both in French and German, and without the aid of written notes, nor haye I, in any way, made use, in the present work, of those portions of my discourses which have been preserved by the industry of certain attentive auditors. With the exception of the first forty pages, the whole of the present work was written, for the first time, in the years 1843 and 1844. A character of unity, freshness, and animation, must, I think, be derived from an association with some definite epoch, where the object of the writer is to delineate the pre- sent condition of knowledge and opinions. Since the addi- tions constantly made to the latter give rise to fundamental changes in pre-existing views, my lectures and the Cosmos have nothing in common beyond the succession in which the various facts are treated. The first portion of my work contains introductory considerations regarding the diversity in the degrees of enjoyment to be derived from nature, and the knowledge of the laws by which the universe is governed; it also considers the limitation and scientific mode of treating a physical description of the universe; and gives a general picture of nature which contains a view of all the phenomena comprised in the Cosmos. This general picture of nature, which embraces vith its wide scope the remotest nebulous spots, and the revolving double stars in the regions of space, no less than the telluric phenomena included under the department of the geography of organic forms (such as plants, animals, and races of men), comprises all that I deem most specially important with regard to the connection existing between generalities and specialities, whilst it moreover exemplifies, by the form and style of the composition, the mode of treatment pursued im the selection of the results obtained from experimental know- ledge. The two succeeding volumes will contain a consi- deration of the particular means of incitement towards the AUTHOR’S PREFACE. xiii study of nature (consisting in animated delineations, land- scape painting, and the arrangement and cultivation of exotic vegetable forms), of the history of the contemplation of the universe, or the gradual development of the reciprocal action of natural forces constituting one natural whole; and lastly, of the special branches of the several departments of science, whose mutual connection is indicated in the begin- ning of the work. Wherever it has been possible to do so I have adduced the authorities from whence I derived my facts, with a view of affording testimony both to the accuracy of my statements and to the yalue of the observations to which refer- ence was made. In those instances where I have quoted from my own writings (the facts contained in which being, from their very nature, scattered through different portions of my works), I have always referred to the original editions, owing to the importance of accuracy with regard to numerical re- lations, and to my own distrust of the care and correct- ness of translators. In the few cases where I have extracted short passages from the works of my friends, I have indicated them by marks of quotation; and, in imitation of the practice of the ancients, I have invariably preferred the repetition of the same words to any arbitrary substitution of my own paraphrases. The much contested question of priority of claim to a first discovery, which it is so dangerous to treat of in a work of this uncontroversial kind, has rarely been touched upon. Where I have occasionally referred to clas- sical antiquity, and to that happy period of transition which has rendered the sixteenth and seventeenth centuries so cele- brated, owing to the great geographical discoveries by which the age was characterised, I have been simply led to adopt this mode of treatment, from the desire we experience from time to time, when considering the general views of nature, to escape from the circle of more strictly dogmatical modern opinions and enter the free and fanciful domain of earlier presentiments. XIV -AUTHOR’S PREFACE. _ It has frequently been regarded as a subject of discouraging consideration, that whilst purely literary products of intellee- tual activity are rooted in the depths of feeling, and inter- woven with the creative force of imagination, all works treat- ing of empirical knowledge, and of the connection of natural phenomena and physical laws, are subject to the most marked modifications of form in the lapse of short periods of time, both by the improvement in the instruments used, and by the consequent expansion of the field of view opened to rational ‘observation, and that those scientific works which have, to use ‘a common expression, become antiquated by the acquisition of new funds of knowledge, are thus continually being consigned to oblivion as unreadable. However discouraging such a prospect ‘must be, no one who is animated by a genuine love of nature, ‘and by a sense of the dignity attached to its study, can view with regret anything which promises future additions and a greater degree of perfection to general knowledge. Many im- portant branches of knowledge have been nas, upon a solid foundation which will not easily be shaken, both as regards the phenomena in the regions of space and on the earth; whilst there are other portions of science in which general views will undoubtedly take the place of merely special; where new forces will be discovered and new substances will be made known, and where those which are now considered as simple will be decomposed. I would therefore venture to hope that an attempt to delineate nature in all its viyid animation and exalted grandeur, and to trace the stable amid the vacil- lating, ever-recurring alternation of physical metamorphoses, will not be wholly disregarded even at a future age. Poisdam, Nov, 1844. CONTENTS OF VOL. I. Page The Translator’s Preface ......... haces nds pele decaapians heoigd an cabana 18 RE RUIROND ETCINCS) pp. 67-145. Il. Terrestrial portion of the Cosmos . ; : . pp. 145-369. a. Form of the earth, its mean density, quantity of heat, electro- magnetic activity, process of light—pp. 145-197. b. Vital activity of the earth towards its external surface. Re-action of the interior of a planet on its crust and surface. Subterranean noise without waves of concussion. Earthquakes dynamic phenomena— pp. 197-213. c. Material products which frequently accompany earthquakes. Gaseous and aqueous springs. Salses and mud-volcanoes. Upheavals of the soil by elastic forces—pp. 213-226. d. Fire-emitting mountains. Craters of elevation. Distribution of volcanoes on the earth—pp. 226-245. e. Volcanic forces form new kinds of rock, and metamorphose those already existing. Geognostical classification of rocks into four groups. Phenomena of contact. Fossiliferous strata; their vertical arrangement. The faunas and floras of an earlier world. Distribution of masses of rock—pp. 245-288. f. Geognostical epochs which are indicated by the mineralogical dif- ference of rocks have determined the distribution of solids and fluids into continents and seas. Individual configuration of solids into hori- zontal expansion and vertical elevation. Bon of area. Articu- lation. Probability of the continued elevation of the earth’s crust in ridges—pp. 288-306. g- Liquid and aeriform envelopes of the solid surface of our planet. Distribution of heat in both. The sea. The tides, Currents and their effects—pp. 306-316. h. The atmosphere. Its chemical composition. Fluctuations in its density. Law of the direction of the winds. Mean temperature. Enu- meration of the causes which tend to raise and lower the temperature, WOL. 1. c [iv] ‘COSMOS. Continental and insular climates. East and west coasts. Cause of the curvature of the isothermal lines. Limits of perpetual snow. Quantity of vapour. LHlectricity in the atmosphere. Forms of the clouds— pp. 316-347, a. Separation of organic terrestrial life from the geography of vital organisms; the geography of vegetables and animals. Physical grada- tions of the human race—(pp. 347-369). Special Analysis of the Delineation of Nature, including references to the subjects treated of in the Notes. I. Celestial portion ofthe Oosmos . . «. .«. « pp. 67-145 . The universe and all that it comprises—multiform nebulous spots, planetary vapour, and nebulous stars. The picturesque charm of a southern sky—(note pp. 68-9). Conjectures on the position in space of the world. Ourstellar masses. A cosmicalisland. Gauging stars. Double stars revolving round a. common centre. Distance of the star 61 Cygni— (p. 72 and note). Our solar system more complicated than was conjec- tured at the close of the last century. Primary planets with Neptune, Astrea, Hebe, Iris, and Flora, now constitute 16; secondary planets 18; myriads of comets, of which many of the inner ones are enclosed in the orbits of the planets; a rotating ring (the zodiacal light) and meteoric stones, probably to be regarded as small cosmical bodies. The teles- copic planets, Vesta, Juno, Ceres, Pallas, Astrea, Hebe, Iris, and Flora, with their frequently intersecting, strongly inclined, and more eccentric orbits, constitute a central group of separation between the inner plane- tary group (Mercury, Venus, the Earth, and Mars), and the outer group (Jupiter, Saturn, Uranus, and Neptune). Contrasts of these planetary groups. Relations of distance from one central body. Dif- ferences of absolute magnitude, density, period of revolution, eccentri- city and inclination of the orbits. The so-called law of the distances of the planets from their central sun. The planets which have the largest number of moons—(p. 80 and note). Relations in space both absolute and relative of the secondary planets. Largest and smallest of the moons. Greatest approximation to a primary planet. Retrogressive movement of the moons of Uranus. Libration of the Earth’s satellite—(p. 83 and note). Comets; the nucleus and tail; various forms and directions of the emanations in conoidal envelopes with more or less dense’walls. Several tails inclined towards the sun; change of form of the tail; its conjectured rotation. Nature of light. Occul- . tations of the fixed stars by the nuclei of comets. Eccentricity of their orbits and periods of revolution. Greatest distance and greatest ap- proximation of comets. Passage through the system of Jupiter's satel- lites. Comets of short periods of revolution, more correctly termed inner comets (Enke, Bicla, Faye)—(p. 94 and note,) Revolving aero- lites (meteoric stones, fire balls, falling stars). Their planetary velocity, magnitude, form, observed height. Periodic return in streams; the November stream and the stream of St. Lawrence. Chemical compo- sition of meteoric asteroids—(p. 117 and note). Ring of zodiacal SUMMARY. [v] light. Limitation of the present solar atmosphere—(p. 130 and note). Translatory motion of the whole solar system—(pp. 185—139 and note). The existence of the law of gravitation beyond our solar system. The milky way of stars and its conjectured breaking up. Milky way of nebulous spots, at right angles with that of the stars. Periods of revo- lutions of bi-coloured double stars. Canopy of stars; openings in the stellar stratum. Events in the universe; the apparition of new stars. Propagation of light, the aspect of the starry vault of the heavens con- yeys to the mind an idea of inequality of time—(pp.139-145 and notes). Il. Yerrestrial portion of the Cosmos . ; : . pp. 145-369 a. Figure of the earth. Density, quantity of heat, electro-magnetic tension, and terrestrial light—(pp. 145-197 and note). Knowledge of the compression and curvature of the earth’s surface acquired by ‘measurements of degrees, pendulum oscillations and certain inequa- lities in the moon’s orbit. Mean density of the earth. The earth’s crust, and the depth to which we are able to penetrate—(p. 151 note). Three-fold movement of the heat of the earth; its thermic condition. Law of the increase of heat with the increase of depth—(p. 152 and note). Magnetism electricity in motion. Periodical variation of ter- restrial magnetism. Disturbance of the regular course of the magneti¢ needle. Magnetic storms; extension of their action. Manifestations of magnetic force on the earth’s surface presented under three classes of phenomena; viz.: lines of equal force (isodynamic); equal inclination (isoclinic); and equal deviation (isogonic). Position of the magnetic pole. Its probable connection with the poles of cold. Change of all the magnetic phenomena of the earth. Erection of magnetic obser- vatories since 1828; a far-extending net-work of magnetic stations— (p. 184 and note). Development of light at the magnetic poles; terres- trial light as a consequence of the electro-magnetic activity of our planet. Elevation of polar light. Whether magnetic storms are ac- companied by noise? Connection of polar light (an electro-magnetic development of light) with the formation of cirrus clouds. Other examples of the generation of terrestrial light—(p. 197 and note). 6. The vital activity of a planet manifested from within outward, the principal source of geognostic phenomena. Connection between merely dynamic concussions or the upheaval of whole portions of the earth’s crust, accompanied by the effusion of matter, and the gene ration of gaseous and liquid fluids, of hot mud and fused earths, which solidify into rocks. Volcanic action in the most general conception ot the idea, is the reaction of the interior of a planet on its outer surface. Earthquakes. Extent of the circles of commotion and their gradual increase. Whether there exists any connection between the changes in terrestrial magnetism and the processes of the atmosphere. Noises, subterranean thunder without any perceptible concussion. The rocks which modify the propagation of the waves of concussion. Upheavals; eruption of water, hot steam, mud mofettes, smoke and flame during an earthquake—(pp. 197-214 and notes). ¢, Closer consideration of material products as .a consequence of [vi] COSMOS. internal planetary activity. There rise from the depths of the carth through fissures and cones of eruption, various gases, liquid fluids (pure or acidulated), mud and molten earths. Volcanoes are a species of intermittent spring. Temperature of thermal springs; their constancy and change. Depth of the foci—(pp. 218-221 and notes). Salses, mud-voleanoes. Whilst fire-emitting mountains being sources of molten _ earths, produce volcanic rocks, spring water forms, by precipitation, | strata of limestone. Continued generation of sedimentary rocks—(p. 226 and note). d. Diversity of volcanic elevations. Dome-like closed trachytic mountains. Actual volcanoes which are formed from craters of eleva- tion or among the detritus of their original structure. Permanent con- nection of the interior of our earth with the atmosphere. Relation to certain rocks. Influence of the relations of height on the frequency of the eruptions. Height of the cone of cinders. Characteristics of those volcanoes which rise above the snow-line. Columns of ashes and fire. Voleanic storm during the eruption. Mineral composition of — lavas—(p. 234 and notes). Distribution of volcanoes on the earth’s surface; central and linear volcanoes; insular and littoral volcanoes. Distance of volcanoes from the sea-coast. Extinction of volcanic forces —/(p. 245 and notes). e. Relation of voleanoes to the character of rocks.— Volcanic forces form new rocks, and metamorphose the more ancient ones. The study ofthese relations leads by a double course to the mineral portion of geognosy, (the study of the textures and of the position of the earth’s strata), and to the configuration of continents and insular groups ele- vated above the level of the sea (the study of the geographical form and outlines of the different parts of the earth.) Classification of rocks according to the scale of the phenomena of structure and metamorphosis, which are still passing before our eyes. Rocks of eruption, sedimentary rocks, changed (metamorphosed) rocks, conglomerates—compound rocks are definite associations of oryctognostically simple fossils. There are four phases in the formative condition; rocks of eruption, endogenous (granite, sienite, porphyry, greenstone, hypersthene, rock, euphotide, me- laphyre, basalt, and phonolithe) ; sedimentary rocks (silurian schist, coal measures, lime stone, travertino, infusorial deposit); metamorphosed rock, which contains also together with the detritus of the rocks of eruption and sedimentary rocks, the remains of gneiss, mica schist, and more ancient metamorphic masses. Aggregate and sandstone forma- tions. The phenomenon of contact explained by the artificial imita- tion of minerals. Effects of pressure and the various rapidity of cooling. Origin of granular or saccharoidal marble, silicification of schist into ribbon jasper. Metamorphosis of caleareous marl into micaceous schist through granite. Conversion of dolomite and gra- nite into argillaceous schist, by contact with basaltic and doleritic rocks. Filling up of the veins from below. Processes of cemen- tation in agglomerate structures. Friction conglomerates—(p. 271 and note). Relative age of rocks, chronometry of the earth’s crust. Fossiliferous strata. Relative age of organisms. Simplicity of the first SUMMARY. [vii] vital forms. Dependence of physiological gradations on the age of the formations. Geognostic horizon, whose careful investigation may yield certain data regarding the identity or the relative age of formations, the periodic recurrence of certain strata, their parallelism, or their total suppression. Types of the sedimentary structures considered in their most simple and general characters; silurian and devonian formations (formerly known as rocks of transition); the lower trias (mountain lime-stone, coal-measures, together with todtliegende and zechstein) ; the upper trias (bunter sandstone, muschelkalk, and keuper) ; jura lime- stone (lias and oolite); free-stone, lower and upper chalk, as the last of the flétz strata, which begin with mountain limestone; tertiary formations in three divisions, which are designated by granular lime- stone, lignite, and south apennine gravel—pp. 271-280. The faunas and floras of an earlier world, and their relations to exist- ing organisms. Colossal bones of antediluvian mammalia in the upper alluvium. Vegetation of an earlier world; monuments of the history of its vegetation. The points at which certain vegetable groups attain their maximum; cycadee in the keuper and lias, and coniferee in the bunter sandstone. Lignite and coal measures (amber-tree). Deposition of large masses of rock ; doubts regarding their origin—p. 288 and note. f. The knowledge of geognostic epochs—of the upheaval of mountain chains and elevated plateaux, by which lands are both formed and destroyed, leads, by an internal causal connection, to the distribution into solids and fluids, and to the peculiarities in the natural configura- tion of the earth’s surface. Existing areal relations of the solid to the fluid differ considerably from those presented by the maps of the physi- cal portion of a more ancient geography. Importance of the eruption of quartzose porphyry with reference to the then existing configuration of continental masses. Individual conformation in horizontal extension (relations of articulation), and in vertical elevation (hypsometrical views). Influence of the relations of the area of land and sea on the temperature, direction of the winds, abundance or scarcity of organic products, and on all meteorological processes collectively. Direction of the major axes of continental masses. Articulation and pyramidal termination towards the south. Series of peninsulas, Valley-like formation of the Atlantic Ocean. Forms which frequently recur— pp. 288-297 and notes. Ramifications and systems of mountain chains, and the means of determining their relative ages. Attempts to deter- mine the centre of gravity of the volume of the lands upheaved above the level of the sea. The elevation of continents is still progressing slowly, and is being compensated for at some definite points by a per- ceptible sinking. All geognostic phenomena indicate a periodical alternation of activity in the interior of our planet. Probability of new elevations of ridges—pp. 297-306 and notes. g. The solid surface of the earth has two envelopes, one liquid, and the other aeriform. Contrasts and analogies which these envelopes—the sea and the atmosphere—present in their conditions of aggregation and elec- tricity, and in their relations of currents and temperature. Depths of the ocean and of the atmosphere, the shoals of which constitute our highlands [ viii | cosMos. and mountain chains. The degree of heat at the surface of the sea in diffe- rent latitudes and in the lower strata. Tendency of the sea to maintain the temperature of the surface in the strata nearest to the atmosphere, in consequence of the mobility of its particles, and the alteration in its density. Maximum of the density of salt water. Position of the zones of the hottest water, and of those having the greatest saline contents. Thermic influence of the lower polar current and the counter-currents in the straits of the sea—pp. 306-309 and notes. General level of the sea, and permanent local disturbances of equilibrium; the periodie disturbances manifested as tides. Oceanic currents; the equatorial or rotation current, the Atlantic warm Gulf-stream, and the further im- pulse which it receives; the celd Peruvian stream in the eastern portion of the Pacific Ocean of the southern zone. Temperature of shoals. The universal diffusion of life in the ocean. Influence of the small sub- marine sylvan region at the bottom of beds of rooted alge, or on far-extending floating layers of fucus—pp. 309-316 and notes. h. The gaseous envelope of our planet, the atmosphere. Chemical composition of the atmosphere, its transparency, its polarisation, pres- sure, temperature, humidity, and electric tension. Relation of oxygen to nitrogen; amount of carbonic acid; carburetted hydrogen; ammo- niacal vapours. Miasmata. Regular (horary) changes in the pres- sure of the atmosphere. Mean barometrical height at the level of the sea in different zones of the earth. Isobarometrical curves. . Baro- metrical windroses. ‘Law of rotation of the winds, and its importance with reference to the knowledge of many meteorological processes. Land and sea winds, trade winds and monsoons—pp. 316-322. Climatic . distribution of heat in the atmosphere, as the effect of the relative posi- tion of transparent and opaque masses, (fluid and solid superficial area,) and of the hypsometrical configuration of continents. Curvature of the isothermal lines in a horizontal and vertical direction, on the earth’s sur- face and in the superimposed strata of air. Conyexity and concavity of the isothermal lines. Mean heat of the year, seasons, months, and days. Enumeration of the causes which produce disturbances in the form of the isothermal lines, z. c. their deviation from the position of the geogra- phical parallels. Isochimenal and isotheral lines are the lines of equal winter and summer heat. Causes which raise or lower the temperature. Radiation of the earth’s surface according to its inclination, colour, density, dryness, and chemical composition. The form of the cloud which announces what is passing in the upper strata of the atmosphere is the image of the strongly radiating ground projected on a hot sum- mer sky. Contrast between an insular or littoral climate, such as ig experienced by all deeply-articulated continents, and the climate of the interior of large tracts of land. East and west coasts. Difference be- tween the southern and northern hemispheres. Thermal scales of culti- vated plants, going down from the vanilla, cacoa, and musacez, to citrons, and olives, and to vines yielding potable wines. The influence which these scales exercise on the geographical distribution of cultivated plants. The favourable ripening and the immaturity of fruits are essentially influ- enced by the difference in the action of direct or scattered light in a SUMMARY. [ix] clear sky, or in one overcast with mist. General summary of the causes which yield a more genial climate to the greater portion of Europe considered as the western peninsula of Asia—p. 333. Determination of the changes in the mean annual and summer temperature, which correspond to one degree of geographical latitude. Equality of the mean temperature of a mountain station, and of the polar distance of any point lying at the level of the sea. Decrease of temperature with the decrease in elevation. Limits of perpetual snow, and the fluctua- tions in these limits. Causes of disturbance in the regularity of the phenomenon. Northern and southern chains of the Himalaya ; habita- bility of the elevated plateaux of Thibet—p. 338. Quantity of moisture in the atmosphere according to the hours of the day, the seasons of the year, degrees of latitude, and elevation. Greatest dryness of the atmo- sphere observed in Northern Asia between the river districts of the Irtysch and the Obi. Dew, a consequence of radiation. Quantity of rain—p. 342. Electricity of the atmosphere, and disturbance of the electric tension. Geographical distribution of storms. Predetermina- tion of atmospheric changes. The most important climatic disturbances cannot be traced at the place of observation te any local cause, but are rather the consequence of some occurrence by which the equilibrium inthe atmospheric currents has been destroyed at some considerable distance. i. Physical geography is not limited to elementary inorganic terres- trial life, but, elevated to a higher point of view, it embraces the sphere of organic life, and the numerous gradations of its typical development. Animal and vegetable life. General diffusion of life in the sea and on the land; microscopic vital forms discovered in the polar ice no less than in the depths of the ocean within the tropics. Extension imparted to the horizon of life by Ehrenberg’s discoveries. Estimation of the mass (volume) of animal and vegetable organisms —pp. 347-356. Geography of plants and animals. Migrations of organisms in the ovum, or by means of organs capable of spontaneous motion. Spheres of distribution depending on climatic relations. Regions of vegetation, and classification of the genera of animals. Isolated and social living plants and animals. The character of floras and faunas is not determined so much by the predominance of separate families in certain parallels of latitude as by the highly complicated relations of the association of many families, and the relative numerical value of their species. The forms of natural families which increase or decrease from the equator to the poles. Inves- tigations into the numerical relation existing in different districts of the earth between each one of the large families to the whole mass of phane- rogamia—pp. 356-560. The human race considered according to its physical gradations, and the geographical distribution of its simultane- ously occurring types. Racesand varieties. All races of men are forms of one single species. Unity of the human race. Languages considered as the intellectual creations of mankind, or as portions of the history of mental activity manifest a character of nationality, although certain his- torical occurrences have been the means of diffusing idioms of the same family of languages amongst nations of wholly different descent— pp. 360-369. Bos 43 ere srl Pah cd es ect at aay This! erie Lis ae ie ey fe cx on i Sy 5 ie fig 5 INTRODUCTION. REFLECTIONS ON THE DIFFERENT DEGREES OF ENJOY- MENT PRESENTED TO US BY THE ASPECT OF NATURE, AND THE STUDY OF HER LAWS. in attempting, after a long absence from my native country, to develope the physical phenomena of the globe, and the simultaneous action of the forces that pervade the regions of space, I experience a twofold cause of anxiety. The subject before me is so inexhaustible and so varied, that I fear either to fall into the superficiality of the encyclopeedist, or to weary the mind of my reader by aphorisms consisting of mere gene- ralities clothed in dry and dogmatical forms. Undue concise- ness often checks the flow of expression, whilst diffuseness is alike detrimental to a clear and precise exposition of our ideas. Nature is a free domain; and the profound conceptions and enjoyments she awakens within us can only be vividly deli- neated by thought clothed in exalted forms of speech, worthy of bearing witness to the majesty and greatness of the creation. _ In considering the study of physical phenomena, not merely in its bearings on the material wants of life, but in its general influence on the intellectual advancement of mankind, we find its noblest and most important result to be a knowledge of the chain of connection, by which all natural forces are linked together, and made mutually dependent upon each other; and it is the perception of these relations that exalts our views and ennobles our enjoyments. Such a result can, however only be reaped as the fruit of observation and intellect, com- bined with the spirit of the age, in which are reflected all the varied phases of thought. He who can trace, through by-gone times, the stream of our knowledge to its primitive source, will learn from history how, for thousands of years, man B 9 : COSMOS. has laboured, amid the ever-recurring changes of form, to recognise the invariability of natural laws, and hat thus by the force of mind gradually subdued a great portion of the phy- sical world to hisdominion. In interrogating the history of the past, we trace the mysterious course of ideas yielding the first glimmering perception of the same image of a Cosmos, or harmoniously ordered whole, which, dimly shadowed forth to the human mind in the primitive ages of the world, is now fully revealed to the maturer intellect of mankind as the result of long and laborious observation. Each of these epochs of the contemplation of the external world—the earliest dawn of thought, and the advanced stage of civilisation—has its own source of enjoyment. In the former, this enjoyment, in accordance with the simplicity. of the primitive ages, flowed from an intuitive feeling of the order that was proclaimed by the invariable and suc- cessive re-appearance of the heavenly bodies, and by the progressive development of organised beings; whilst in the laiter, this sense of enjoyment springs from a definite know- ledge of the phenomena of nature. When man began to, interrogate nature, and, not content with observing, learnt to evoke phenomena under definite conditions ; when once he sought to collect and record facts, in order that the fruit of his labours might aid investigation after his own brief exist- ence had passed away, the philosophy of Nature cast aside the vague and poetic garb in which she had been enveloped from her origin, and having assumed a severer aspect, she now weighs the value of observations, and substitutes induction and reasoning for conjecture and assumption. The dogmas of former ages survive now only in the superstitions of the people and the prejudices of the ignorant, or are perpetuated in a few systems, which, conscious of their weakness, shroud themselves in a veil of mystery. _We may also trace the same primitive intuitions in languages exuberant in figurative expressions; and a few of the best chosen symbols engendered by the happy inspiration of the earliest ages, having by degrees lost their vagueness through a better mode of inter- pretation, are still preserved amongst our scientific terms. Nature considered rationally, that is to say, submitted to the process of thought, is a unity in diversity of phenomena 5 a harmony, blending together all created things, however dis- i | INTRODUCTION. 8 similar in form and attributes; one great whole (ro may)/ animated by the breath of life. The most important result of a rational inquiry into nature is, therefore, to establis the unity and harmony of this stupendous mass of force an matter, to determine with impartial justice what is due to th discoveries of the past and to those of the present, and t analyze the individual parts of natural phenomena without succumbing beneath the weight of the whole. Thus, and thus alone, is it permitted to man, while mindful of the high destiny of his race, to comprehend nature, to lift the veil that shrouds her phenomena, and, as it were, submit the results of observation to the test of reason and of intellect. . In reflecting upon the different degrees of enjoyment pre- sented to us in the contemplation of nature, we find that the first place must be assigned to a sensation, which is wholly independent of an intimate acquaintance with the physical phenomena presented to our view, or of the peculiar cha- racter of the region surrounding us. In the uniform plain bounded only by a distant horizon, where the lowly heather, the cistus, or waving grasses, deck the soil; on the ocean shore, where the waves, softly rippling over the beach, leave a track, green with the weeds of the sea; everywhere, the mind is penetrated by the same sense of the grandeur and vast expanse of nature, revealing to the soul, by a mysterious inspiration, the existence of laws that regulate the forces of the universe. Mere communion with nature, mere contact with the free air, exercise a soothing yet strengthening influ- ence on the wearied spirit, calm the storm of passion, and soften the heart when shaken by sorrow to its inmost depths. Everywhere, in every region of the globe, in every stage of intellectual culture, the same sources of enjoyment are alike vouchsafed toman. The earnest and solemn thoughts awakened by a communion with nature intuitively arise from a presen- timent of the order and harmony pervading the whole uni- verse, and from the contrast we draw between the narrow limits of our own existence and the image of infinity revealed on every side, whether we look upwards to the starry vault of heaven, scan the far-stretching plain before us, or seek to trace the dim horizon across the vast expanse of ocean. . The contemplation of the individual characteristics of the landscape, and of the conformation of the land in any definite B2 4 COSMOS. region of the earth, gives rise to a different source of enjoy- ment, awakening impressions that are more vivid, better defined, and more congenial to certain phases of the mind, than those of which we have already spoken. At one time the heart is stirred by a sense of the grandeur of the face of nature, by the strife of the elements, or, as in Northern Asia, by the aspect of the dreary barrenness of the far-stretching steppes; at another time, softer emotions are excited by the contemplation of rich harvests wrested by the hand of man from the wild fertility of nature, or by the sight of human habitations raised beside some wild and foaming torrent. Here I regard less the degree of intensity, than the difference existing in the various sensations that derive their charm and permanence from the peculiar character of the scene. If I might be allowed to abandon myself to the recollec- tions of my own distant -travels, I would instance, among the most striking scenes of nature, the calm sublimity of a tropicat night, when the stars, not sparkling, as in our northern skies, shed their soft and planetary ight over the gently-heaving ocean ;—or I would recall the deep valleys of the Cordilleras, where the tall and slender palms pierce the leafy veil around them, and waving on high their feathery and arrow-like branches, form, as it were, ‘a forest above a forest ;”* or I would describe the summit of the Peak of Teneriffe, when a horizontal layer of cleuds, dazzling in whiteness, has separated the cone of cinders from the plain below, and suddenly the ascending current pierces the cloudy veil, so that the eye of the traveller may range from the brink of the crater, along the vine-clad slopes of Orotava, to the orange-gardens and banana- groves that skirt the shore. In scenes like these, it is not the peaceful charm uniformly spread over the face of nature that moves the heart, but rather the peculiar physiognomy and con- formation of the land, the features of the landscape, the ever- varying outline of the clouds, and their blending with the horizon of the sea, whether it lies spread before us like a smooth and shining mirror, or is dimly seen through the morning mist. All that the senses can but imperfectly com- prehend, all that is most awful in such romantic scenes of nature, may become a source of enjoyment to man, by open- * This expression is taken from a beautiful description of tropical forest scenery in Paul and Virginia, by Bernardin de Saint Pierre. INTRODUCTION, 5 ing a wide field to the creative powers of his imagination. Impressions change with the varying movements of the mind, and we are led by a happy illusion to believe that we receive from the external world that with which we have ourselves| invested it. When far from our native country, after a long voyage, we tread for the first time the soil of a tropical land, we experi- ence a certain feeling of surprise and gratification in recog- nising, in the rocks that surround us, the same inclined schistose strata, and the same columnar basalt covered with cellular amygdaloids, that we had left in Europe, and whose identity of character, in latitudes so widely different, reminds us, that the solidification of the earth’s crust is altogether independent of climatic influences. But these rocky masses of schist and of basalt are covered with vegetation of a character with which we are unacquainted, and of a physiognomy wholly unknown to us; and it is then, amid the colossal and majestic forms of an exotic flora, that we feel how wonderfully the flexibility of our nature fits us to receive new impressions, linked together by a certain secret analogy. We so readily perceive the affinity existing amongst all the forms of organic life, that although the sight of a vegetation similar to that of our native country might at first be most welcome to the eye, as the sweet familiar sounds of our mother tongue are to the ear, we nevertheless, by degrees, and almost imperceptibly, become familiarised with a new home and a new climate. Asa true) citizen of the world, man everywhere habituates himself to | that which surrounds him; yet fearful, as it were, of breaking the links of association that bind him to the home of his child- hood, the colonist applies to some few plants in a far distant clime the names he had been familiar with in his native land; and by the mysterious relations existing amongst all types of egamsation, the forms of exotic vegetation present them- — selves to his mind as nobler and more perfect developments of those he had loved in earlier days. Thus do the spontaneous impressions of the untutored mind lead, like the laborious deductions of cultivated intellect, to the same intimate per- suasion, that one sole and indissoluble chain binds together all nature. Tt may seem a rash attempt to endeavour to separate, into its different elements, the magic power exercised upon our minds 6 COSMOS. by the physical world, since the character of the landscape, and of every imposing scene in nature, depends so materially upon the mutual relation of the ideas and sentiments simultaneously _ excited in the mind of the observer. The powerful effect exercised by nature springs, as it were, from the connection and unity of the impressions and emotions produced ; and we can only trace their different sources by analysing the individuality of objects, and the diversity of forces. The richest and most varied elements for pursuing an analysis of this nature present themselves to the eyes of the traveller in the scenery of Southern Asia, in the Great Indian Archipelago, and more especially, too, in the New Continent, where the summits of the lofty Cordilleras pene- trate the confines of the aerial ocean surrounding our globe, and where the same subterranean forces that once raised these mountain chains, still shake them to their foundation an threaten their downfall. | Graphic delineations of nature, arranged according to sys- tematic views, are not. only suited to please the imagination, but may also, when properly considered, indicate the grades of the impressions of which I have spoken, from the uni- — formity of the sea-shore, or the barren steppes of Siberia, to the inexhaustible fertility of the torrid zone. If we were even to picture to ourselves Mount Pilatus placed on the Schreckhorn,* or the Schneekoppe of Silesia on Mont Blane, * These comparisons are only approximative. The several elevations above the level of the sea are, in accurate numbers, as follows:— The Schneekoppe or Riesenkoppe, in Silesia, about 5,270 feet, accord- ing to Hallaschka. The Righi 5,902 feet, taking the height of the Lake of Lucerne at 1426 feet, according to Eschman. (See Compte Rendu des Mesures Trigonométriques en Suisse, 1840, p. 239.) Mount Athos 6,775 feet, according to Captain Gaultier; Mount Pilatus 7,546 feet; Mount Etna 10,871 feet, according to Captain Smyth; or 10,874 feet, according to the barometrical measurement made by Sir John Herschel, and com- municated to me in writing in 1825, and 10,899 feet, according to angles of altitude taken by Cacciatore at Palermo (calculated, by assuming the terrestrial refraction to be 0°076); the Schreckhorn 12,383 feet; the Jungfrau 13,720 feet, according to Tralles; Mont Blanc 15,775 feet, according to the different measurements considered by Roger (Bil. Univ., May, 1828, pp. 24—53), 15,733 feet, according to the measurements taken from Mount Columbier by Carlini, in 1821, and 15,748 feet, as measured by the Austrian engineers from Trelod andthe Glacier d’Ambin, INTRODUCTION. 7 we should not have attained to the height of that great Colos- sus of the Andes, the Chimborazo, whose height is twice that of Mount Etna; and we must pile the Righi, or Mount Athos, on the summit of the Chimborazo, in order to form a just estimate of the elevation of the Dhawalagiri, the highest point The actual height of the Swiss mountains fluctuates, according to Eschman’s observations, as much as 25 English feet, owing to the varying thickness of the stratum of snow that covers the summits. Chimborazo is, according to my trigonometrical measurements, 21,421 feet, (see Hum- boldt, Recueil d’Obs. Astr., tome i., p. 73), and Dhawalagiri 28,074 feet. As there is a difference of 445 feet between the determinations of Blake and Webb, the elevation assigned to the Dhawalagiri, (or white mountain from the Sanscrit dhawala, white, and giri, mountain), cannot be received with the same confidence as that of the Jawahir. 25,749 feet. since the latter rests on a complete trigonometrical measurement, (see Herbert and Hodgson in the Asiat. Res., vol. xiv., p. 189, and Suppl. to Encycl. Brit., vol. iv., p. 643.) I have shown elsewhere (Ann. des Sciences Naturelles, Mars, 1825,) that the height of the Dhawalagiri (28,074 feet) depends on several elements that have not been ascertained with certainty, as azimuths and latitudes, (Humboldt, Asie Centrale, t. iii., p- 282). It has been believed, but without foundation, that in the Tar- taric chain, north of Thibet, opposite to the chain of Kouen-iun, there are several snowy summits, whose elevation is about 30,000 English feet, (almost twice that of Mont Blanc,) or, at any rate, 29,000 feet, (see Captain Alexander Gerard’s and John Gerard’s Journey to the Boorendo Pass, 1840, vol. i., pp. 143 and 311). Chimborazo is spoken of in the text only as one of the highest summits of the chain of the Andes; for in the year 1827, the learned and highly gifted traveller, Pentland, in his memorable expedition to Upper Peru (Bolivia), measured the elevation of two mountains situated to the east of Lake Titicaca, viz., the Sorata 25,200 feet, and the Illimani 24,000 feet, both greatly exceeding the height of Chimborazo, which is only 21,421 feet, and being nearly equal in elevation to the Jawahir, which is the highest mountain in the Himalaya, that has as yet been accurately measured. Thus Mont Blanc is 5,646 feet below Chimborazo; Chimborazo 3,779 feet below the Sorata; the Sorata 549 feet below the Jawahir, and probably about 2,880 feet below the Dhawalagiri. According to a new measurement of the Illimani, by Pentland, in 1838, the elevation of this mountain is given at 23,868 feet, varying only 133 feet from the measurement taken in 1827. The elevations have been given in this note with minute exactness, as erroneous numbers have been introduced into many maps and tables recently pubes, lished, owing to incorrect reductions of the measurements. [In the preceding note, taken from those appended to the Introduction in the French Translation, rewritten by Humboldt himself, the measure- ments are given in metres, but these have been converted into English feet for the greater convenience of the general reader. ]—Zr. 8 cOSMOS. of the Himalaya. But although the mountains of India greatly surpass the Cordilleras of South America, by their astonishing elevation, (which after being long contested has at last been confirmed by accurate measurements,) they cannot, from their geographical position, present the same inexhaustible variety of phenomena by which the latter are characterised. ‘The impression produced by the grander aspects of nature does not depend exclusively on height. The chain of the Himalaya is placed far beycnd the limits of the torrid zone, and scarcely is a solitary palm-tree to be found in the beautiful valleys of Kumaoun and Garhwal.* On the southern slope of the ancient Paropamisus, in the latitudes of 28° and 34°, nature no longer displays the same abundance of tree-ferns, and arborescent grasses, heliconias and orchideous plants, which in tropical regions are to be found even on the highest plateaux of the mountains. On the slope of the Himalaya, under the shade of the Deodora and the broad-leaved oak, peculiar to these Indian Alps, the rocks of granite and of mica schist are covered with vegetable forms, almost similar to those which characterise Europe and Northern Asia. The species are not identical, but closely analogous in aspect and physiognomy, as for instance, the juniper, the alpine birch, the gentian, the marsh parnassia, and the prickly species of Ribes.t| The * The absence of palms and tree-ferns on the temperate slopes of the Himalaya is shown in Don’s Flora Nepalensis, 1825, and in the remark- able series of lithographs of Wallich’s Flora Indica, whose catalogue contains the enormous number of 7,683 Himalaya species, almost all phanerogamic plants, which have as yet been but imperfectly classified. In Nepaul (lat. 264° to 274°) there has hitherto been observed only one species of palm, Chameerops martiana, Wall. (Plante Asiat., lib. iii., pp.5, 211), which is found at the height of 5,250 English feet above the level of the sea, in the shady valley of Bunipa. The magnificent tree-fern, Alsophila brunoniana, Wall. (of which a stem 48 feet long has been in the possession of the British Museum since 1831) does not grow in Nepaul, but is found on the mountains of Silhet, to the north-west of Calcutta, in lat. 24°50’. The Nepaul fern, Paranema cyathdides, Don, formerly known as Spheroptera barbata, Wall. (Plante Asiat., lib.i., pp. 42,48) is, indeed, nearly related to Cyathea, a species of which I have seen in the South American Missions of Caripe, measuring 33 feet in height; this is not, however, properly speaking, a tree. + Ribes nubicola, R. glaciale, R. grossuylaria. The species which compose the vegetation of the Himalaya are four pines, notwithstanding the assertion of the ancients regarding Eastern Asia (Strabo, lib. 11, INTRODUCTION. 9 . chain of the Himalaya is also wanting in the imposing pleno- mena of yvoleanoes, which in the Andes and in the Indian Archipelago often reveal to the inhabitants, under the most terrific forms, the existence of the forces pervading the interior of our planet. . Moreover, on the southern declivity of the Himalaya, where the ascending current deposits the exhalations rising from a vigorous Indian vegetation, the region of perpetual snow begins at an elevation of 11,000 or 12,000 feet above the level of the sea,* thus setting a limit to the development of p- 510, Cas.), twenty-five oaks, four birches, two chesnuts, seven maples, twelve willows, fourteen roses, three species of strawberry, seven species of Alpine roses (rhododendra), one of which attains a height of 20 feet, and many other northern genera. Large white apes, having black faces, inhabit the wild chesnut-tree of Kashmir, which grows to a height of 100 feet, in lat. 33° (see Carl Von Hiigel’s Kaschmir, 1840, 2nd pt., 249.) Among the conifere, we find the Pinus deodwara, or deodara (in Sanscrit, déwa-daru—the timber of the gods), which is nearly allied to Pinus cedrus. Near the limit of perpetual snow, flourish the large and showy flowers of the Gentiana venusta, G. Moorcroftiana, Swertia pur- purescens, S. speciosa, Parnassia armata, P. nubicola, Poeonia Emodi, Tulipa stellata; and, besides varieties of European genera peculiar to these Indian mountains, true European species, as Leontodon taraxacum, Pru- nella vulgaris, Galium aparine, and Thlaspi arvense. The heath men- tioned by Saunders, in Turner’s Travels, and which had been confounded with Calluna vulgaris, is an Andromeda, a fact of the greatest importance in the geography of Asiatic plants. If I have made use, in this work, of the unphilosophical expressions of European genera, European species, growing wild in Asia, &c., it has been in consequence of the old botanical language, which instead of the idea of a large dissemination, or rather of the co-existence of organic productions, has dogmatically substituted the false hypothesis of a migration, which from predilection for Europe, is further assumed to have been from west to east. * On the southern declivity of the Himalaya, the limit of perpetual snow is 12,978 feet above the level of the sea; on the northern declivity, or rather on the peaks which rise above the Thibet, or Tartarian plateau, this limit is at 16,625 feet from 304° to 32° of latitude, whilst at the equator, in the Andes of Quito, it is 15,790 feet. Such is the result I have deduced from the combination of numerous data furnished by Webb, Gerard, Herbert, and Moorcroft. (See my two memoirs on the mountains of India, in 1816 and 1820, in the Ann. de Chimie et de Phys sique, t. ili. p, 303, t. xiv. pp. 6, 22,50.) The greater elevation to which the limit of perpetual snow recedes on the Tartarian declivity is owing to the radiation of heat from the neighbouring elevated plains, to the purity of the atmosphere, and to the infrequent formation of snow in an air which is both very cold and very dry. (Humboldt, Asie Centrale, t. iii, 10 COSMOS. « organic life in a zone that is nearly 3000 feet lower than that to which it attains in the equinoctial region of the Cor- dilleras. But the countries bordering on the equator possess another pp- 281-326.) My opinion on the difference of height of the snow-line on the two sides of the Himalaya has the high authority of Colebrooke in its favour. He wrote to me in June, 1824, as follows :—‘“‘I also find, from the data in my possession, that the elevation of the line of perpetual snow is 13,000 feet. On the southern declivity, and at lat. 31°, Webb’s mea- surements give me 13,500 feet, consequently 500 feet more than the height deduced from Captain Hogdson’s observations. Gerard’s mea- surements fully confirm your opinion that the line of snow is higher on the northern than on the southern side’’ It was not until the present year (1840) that we obtained the complete and collected journal of the brothers Gerard, published under the supervision of Mr. Lloyd. (Narra- tive of a Journey from Cawnpoor to the Boorendo Pass, in the Himalaya, by Captain Alexander Gerard and John Gerard, edited by George Lloyd, voi. i. pp. 291, 311, 320, 327, and 341.) Many interesting details re- garding some localities may be found in the narrative of A visit to the Shatool, for the purpose of determining the line of perpetual snow on the southern face of the Himalaya, in August, 1822. Unfortunately, how- ever, these travellers always confound the elevation at which sporadic snow falls, with the maximum of the height that the snow-line attains on the Thibetian plateau. Captain Gerard distinguishes between the summits that rise in the middle of the plateau, where he states the elevation of the snow-line to be between 18,000 and 19,000 feet, and the northern slopes of the chain of the Himalaya, which border on the defile of the Sutledge, and can radiate but little heat, owing to the deep ravines with which they are intersected. The elevation of the village of Tangno is given at only 9300 feet, while that of the plateau surrounding the sacred lake of Manasa is 17,000 feet. Captain Gerard finds the snow-line 500 feet lower on the northern slopes, where the chain of the Himalaya is broken through, than towards the southern declivities facing Hindostan, and he there estimates the line of perpetual snow at 15,000 feet. The most striking differences are presented between the vegetation on the Thibetian plateau, and that characteristic of the southern slopes of the Himalaya. On the latter the cultivation of grain is arrested at 9974 feet, and even there the corn has often to be cut when the blades are still green. The extreme limit of forests of tall oaks and deodars is 11,960 feet; that of dwarf birches }2,983 feet. On the plains, Captain Gerard found pastures up to the height of 17,000 feet; the cereals will grow at 14,100 feet, or even at 18,540 feet ; birches with tall stems at 14,100 feet, and copse or brush- wood applicable for fuel is found at an elevation of upwards of 17,000 feet, that is to say, 1280 feet above the lower limits of the snow-line at the equator, in the province of Quito. It is very desirable that the mean elevation of the Thibetian plateau, which I have estimated at only about $200 feet between the Himalaya and the Kouen-Lun, and the difference in ~ INTRODUCTION. 11 advantage, to which sufficient attention has not hitherto been directed. This portion of the surface of the globe affords in the smallest space the greatest possible variety of impressions from the contemplation of nature. Among the colossal moun- the height of the line of perpetual snow on the southern and on the northern slopes of the Himalaya, should be again investigated by tra- vellers who are accustomed to judge of the general conformation of the ‘land. Hitherto simple calculations have too often been confounded with actual measurements, and the elevations of isolated summits with that of the surrounding plateau. (Compare Carl Zimmerman’s excellent Hypso- metrical Remarks in his Geographischen Analyse der Karte von Inner Asien, 1841, s. 98.) Lord draws attention to the difference presented by the two faces of the Himalaya and those of the Alpine chain of Hindoo- ‘Coosh, with respect to the limits of the snow-line. ‘‘ The latter chain,”’ he says, ‘‘ has the table-land to the south, in consequence of which the snow-line is higher on the southern side, contrary to what we find to be the case with respect to the Himalaya, which is bounded on the south by shel- tered plains, as Hindoo-Coosh is on the north.’’ It must, however, be ad- mitted thatthe hypsometrical data, on which these statements are based, re- quire a critical revision with regard to several of their details ; but still they _ suffice to establish the main fact, that the remarkable configuration of the land in Central Asia affords man all that is essential to the maintenance of life, as habitation, food, and fuel, at an elevation: above the level of the sea, ‘which in almost all other parts of the globe is covered with perpetual ice. We must except the very dry districts of Bolivia, where snow is so rarely met with, and where Pentland (in 1838) fixed the snow-line at 15,667 feet, between 16° and 173° south latitude. The opinion that I had ad- vanced regarding the difference in the snow-line on the two faces of the Himalaya has been most fully confirmed by the barometrical observations of Victor Jacquemont, who feil an early sacrifice to his noble and unwea- ried ardour. (See his Correspondance pendant son voyage dans I’ Inde, 1828 a 1832, liv. 23, pp. 290, 296, 299.) ‘‘ Perpetual snow,’’ says Jacquemont, ‘‘ descends lower on the southern than on the northern slopes of the Himalaya, and the limit constantly rises as we advance to the north of the chain bordering on India. On the Kioubrong, about 18,317 feet in elevation, according to Captain Gerard, I was still considerably below the limit of perpetual snow, which, I believe to be 19,690 feet in’ this part of Hindostan.’’ (This estimate I consider much too high.) The same traveller says, ‘*To whatever height we rise on the southern declivity of the Himalaya, the climate retains the same character, and the same division of the seasons as in the plains of India; the summer solstice being every year marked by the same prevalence of rain, which continues to fall without intermission until the autumnal equinox. But a new, a totally different climate begins at Kashmir, whose elevation I estimate to be 5350 feet, nearly equal to that of the cities of Mexico and Popayan,”’ (Correspond. de Jacquemont, t. ii., pp. 58 et 74). The warm and humid air of the sea, as Leopold von Buch well observes, is carried by the mon- 12 COSMOS. tains of Cundinamarca, of Quito, and of Peru, furrowed by deep ravines, man is enabled to contemplate alike all the families of plants, and all the stars of the firmament. There, at a single glance, the eye surveys majestic palms, humid forests of bambusa, and the varied species of musacez, while above these forms of tropical vegetation appear oaks, medlars, the sweetbrier, and umbelliferous plants, as in our European homes. There, as the trayeller turns his eyes to the vault of heaven, a single glance embraces the constellation of the Southern Cross, the Magellanic clouds, and the guiding stars of the constellation of the Bear, as they circle round the arctic pole. There the depths of the earth and the vaults of heaven display all the richness of their forms and the variety of their phenomena. There the different climates are ranged the one above the other, stage by stage, like the vegetable zones, whose succession they limit; and there the observer may readily trace the laws that regulate the diminution of heat, as they stand indelibly inscribed on the rocky walls and abrupt declivities of the Cordilleras. | Not to weary the reader with the details of the phenomena which I long since endeavoured graphically to represent,* I soons across the plains of India to the skirts of the Himalaya, which arrest its course, and hinder it from diverging to the Thibetian districts of Ladak and Lassa. Carl von Hiigel estimates the elevation of the valley of Kashmir above the level of the sea at 5818 feet, and bases his observation on the determination of the boiling point of water, (see theil 11, s. 155, and Journal of Geog. Soc., vol. vi. p. 215). In this valley, where the atmosphere is scarcely ever agitated by storms, and in 34° 7’ lat., snow is found, several feet in thickness, from December to March. * See, generally, my Essai sur la Géographie des Plantes, et le Tableau physique des Régions Equinowxiales, 1807, pp. 80-88. On the diurnal and nocturnal variations of temperature, see Plate 9 of my Aélas Géogr. et Phys. du Nouveau Continent; and the Tables in my work, entitled De distributione geographica Plantarum secundum celi tems periem et aliitudinem montium, 1817, pp. 90-116; the meteorological portion of my Asie Centrale, tom. iii., pp. 212, 224; and, finally, the more recent and far more exact exposition of the variations of temperature experienced in correspondence with the increase of altitude on the chain of the Andes, given in Boussingault’s Memoir, Sur la profondeur a la- quelle on trouve, sous les Tropiques, la couche de Temperature Invariable, (Ann. de Chimie et de Physique, 1833, t. liii., pp. 225-247.) This treatise contains the elevations of 128 points, included between the level of the sea and the declivity of the Antisana (17,900 feet), as well as the mean temperature of the atmosphere, which varies with the height between 81° and 35° F. INTRODUCTION. 13 will here limit myself to the consideration of a few of the general results whose combination constitutes the physical delineation of the torrid zone. That which, in the vagueness of our impressions, loses all distinctness of form, like some distant mountain shrouded from view by a veil of mist, is clearly revealed by the light of mind, which by its scrutiny into the causes of phenomena learns to resolve and analyze their different elements, assigning to each its mdividual cha- racter. Thus in the sphere of natural investigation, as in poetry and painting, the delineation of that which appeals most strongly to the imagination, derives its collective interest from the vivid truthfulness with which the individual features are pourtrayed. The regions of the torrid zone not only give rise to the most powerful impressions by their organic richness and their abundant fertility, but they likewise afford the inestimable advantage of revealing to man, by the uniformity of the varia- tions of the atmosphere and the development of vital forces, and by the contrasts of climate and vegetation exhibited at different elevations, the invariability of the laws that regulate the course of the heavenly bodies, reflected, as it were, in terrestrial phenomena. Let us dwell then for a few moments on the proofs of this regularity, which is such, that it may be submitted to numerical calculation and computation. In the burning plains that rise but little above the level of the sea, reign the families of the banana, the cycas, and the palm, of which the number of species comprised in the flora of tropical regions has been so wonderfully increased in the present day, by the zeal of botanical travellers. To these groups succeed, in the Alpine valleys and the humid and shaded clefts on the slopes of the Cordilleras, the tree-ferns, whose thick cylindrical trunks and delicate lacelike foliage stand out in bold relief against the azure of the sky, and the cinchona, from which we derive the febrifuge bark. The medicinal strength of this bark is said to increase in propor- tion to the degree of moisture imparted to the foliage of the tree by the light mists which form the upper surface of the clouds resting over the plains. Everywhere around, the con- fines of the forest are encircled by broad bands of social lants, as the delicate aralia, the thibaudia and the myrtle- ved andromeda, whilst the Alpine rose, the magnificent Ns 4 COSMOS. befaria, weaves a purple girdle round the spiry peaks. In the cold regions of the Paramos, which is continually exposed to the fury of storms and winds, we find that flowering shrubs and herbaceous plants, bearing large and variegated blossoms, have given place to monocotyledons, whose slender spikes constitute the sole covering of the soil. This is the zone of the grasses, one vast savannah extending over the immense mountain plateaux, and refiecting a yellow, almost golden tinge, to the slopes of the Cordilleras, on which graze the lama and the cattle domesticated’ by the European colonist. Where the naked trachyte rock pierces the grassy turf and penetrates into those higher strata of air which are supposed to be less charged with carbonic acid, we meet only with plants of an inferior organisation, as lichens, lecideas, and the brightly-coloured dustlike lepraria, scattered around in circular patches. Islets of fresh-fallen snow, varying in form and extent, arrest the last feeble traces of vegetable develop- ment, and to these succeeds the region of perpetual snow, whose elevation undergoes but little change, and may be easily determined. It is but rarely that the elastic forces at work within the interior of our globe, have succeeded in breaking through the spiral domes, which, resplendent in the brightness of eternal snow, crown the summits of the Cordil- leras—and even where these subterranean forces have opened a permanent communication with the atmosphere, through circular craters or long fissures, they rarely send forth cur- rents of lava, but merely eject ignited scorie, steam, sulphu- retted hydrogen gas, and jets of carbonic acid. In the earliest stages of civilisation the grand and imposing spectacle presented to the minds of the inhabitants of the tropics could only awaken feelings of astonishment and awe. It might perhaps be supposed, as we have already: said, that the periodical return of the same phenomena, and the uniform manner in which they arrange themselves in ‘ successive groups, would have enabled man more readily to attain to a knowledge of the laws of nature; but as far as tradition and history guide us, we do not find that any application was made of the advantages presented by these favoured regions. Recent researches have rendered it very doubtful whether the primitive seat of Hindoo civilisation—one of the most remarkable phases in the progress of mankind—was actually INTRODUCTION.» 15 within the tropics. Airyana Vaedjo, the ancient cradle of the Zend, was situated to the north-west of the upper Indus, and. after the great religious schism, that is to say, after the separation of the Iranians from the Brahminical institution, the language that had previously been common to them and to the Hindoos, assumed amongst the latter people (together with the literature, habits, and condition of society) an indi- vidual form in the Magodha or Madhya Desa,* a district that is bounded by the great chain of Himalaya and the smaller range of the Vindhya. In less ancient times the Sanscrit language and civilisation advanced towards the south- east, penetrating further within the torrid zone, as my brother Wiihelm von Humboldt has shown in his grea$ work on the Kavi and other languages of analogous structure.} Notwithstanding the obstacles opposed in northern lati- tudes to the discovery of the laws of nature, owing to the excessive complication of phenomena, and the perpetual local variations that, in these climates, affect the movements of the atmosphere and the distribution of organic forms; it is to the inhabitants of a small section of the temperate zone, that the rest of mankind owe the earliest revelation of an intimate and rational acquaintance with the forces governing the physical world. Moreover, it is from the same zone (which is appa- rently more fayourable to the progress of reason, the soften- ing of manners, and the security of public liberty), that the germs of civilisation have been carried to the regions of the tropics, as much by the migratory movement of races as by the establishment of colonies, differing widely in their insti- tution from those of the Phenicians or Greeks. In speaking of the influence exercised by the succession of phenomena on the greater or lesser facility of recognising the causes producing them, I have touched upon that important * See, on the Madhjadéca, properly so called, Lassen’s excellent work, entitled Indische Alterthumskunde, bd.i., s. 92. The Chinese give the name of Mo-kie-thi to the southern Bahar, situated to the south of the Ganges, (see Foe-Koue-Ki, by Chy-Fa-Hian, 1836, p. 256). Djambu-dwipa is the name given to the whole of India; but the words also indicate one of the four Budhist continents. + Ueber die Kawi Sprache auf der Insel Java, nebst einer Einleitung tiber die Versehiedenheit des menschlichen Sprachbaues und ihren influss auf die geistige Entwickelung des Menschengeschilecht’s, von Wilhelm v, Humholdt, 1836, bd, i., s. 5—510. . 16 COSMOS. stage of our communion with the external world, when the enjoyment arising from a knowledge of the laws, and the mutual connection of phenomena, associates itself with the charm of a simple contemplation of nature. That which for a long time remains merely an object of vague intuition, by degrees acquires the certainty of positive truth; and man, as an immortal poet has said, in our own tongue—Amid ceaseless change seeks the unchanging pole. * In order to trace to its primitive source the enjoyment derived from the exercise of thought, it is sufficient to cast a rapid glance on the earliest dawnings of the philosophy of nature, or of the ancient doctrine of the Cosmos. We find even amongst the most savage nations (as my own travels enable me to attest), a certain vague, terror-stricken sense of the all-powerful unity of natural forces, and of the existence of an) ; invisible, spiritual essence manifested in these forces, whether in unfolding the flower and maturing the fruit of the nutrient’ | tree, in upheaving the soil of the forest, or in rending the clouds with the might of the storm. "We may here trace the revela- tion of a bond of union, linking together the visible world and that higher spiritual world which escapes the grasp of the _ senses. The two become unconsciously blended together, developing in the mind of man, as a simple product of ideal conception, and independently of the aid of observation, the first germ of a Philosophy of Nature. Amongst nations least advanced in civilisation, the imagi- nation revels in strange and fantastic creations; and by its predilection for symbols, alike influences ideas and language. | Instead of examining, men are led to conjecture, dogmatize, and interpret supposed facts that have never been observed. ‘The inner world of thought and of feeling does not reflect the image of the external world in its primitive purity. That which in some regions of the earth manifested itself as the rudiments of natural philosophy, only to a small number of persons endowed with superior intelligence, appears in other regions, and among entire races of men, to be the result of mystic tendencies and instinctive intuitions. An intimate | communion with nature, and the vivid and deep emotions | thus awakened, are likewise the source from which have \ * This verse occurs in a poem of Schiller, entitled Der Spazrergang, which first appeared, in 1795, in the Horen. INTRODUCTION. 17 sprung the first impulses towards the worship and deification | of the destroying and preserving forces of the universe. But ° by degrees as man, after having passed through the different gradations of intellectual development, arrives at the free enjoyment of the regulating power of reflection, and learns by gradual progress, as it were, to separate the world of ideas from that of sensations, he no longer rests satisfied merely with a vague presentiment of the harmonious unity of natural forces; thought begins to fulfil its noble mission ; and observation, aided by reason, endeavours to trace phenomena to the causes from which they spring. The history of science teaches us the difficulties that have opposed. the progress of this active spirit of inquiry. Inaccu- rate and imperfect observations have led by false,inductions to the great number of physical views that have been per- petuated as popular prejudices among all classes of society. Thus by the side of a solid and scientific knowledge of natural phenomena there has been preserved a system of the pre- tended results of observation, which is so much the more difficult to shake, as it denies the validity of the facts by which it may be refuted. This empiricistn, the melancholy heritage transmitted to us from former times, invariably contends for the truth of its axioms with the arrogance of a narrow- minded spirit. Physical philosophy, on the other hand, when based upon science, doubts because it seeks to investigate, distinguishes between that which is certain and that which is merely probable, and strives incessantly to perfect theory by extending the circle of observation. This assemblage of imperfect dogmas bequeathed by one age to another—this physical philosophy, which is composed of popular prejudices,—is not only injurious because it per- petuates error with the obstinacy engendered by the evidence of ill observed facts, but also because it hinders the mind from attaining to higher views of nature. Instead of seeking to’ discover the mean or medium point, around which oscillate, in apparent independence of forces, all the phenomena of the external world, this system delights in multiplying exceptions to the law, and seeks, amid phenomena and in organic forms, for something beyond the marvel of a regular succession, and an internal and progressive development. Ever inclined to believe that the order of nature is disturbed, it refuses to Cc 18 COSMOS. recognise in the present any analogy with the past, and guided by its own varying hypotheses, seeks at hazard, either in the interior of the globe or in the regions of space, for the cause of these pretended perturbations. It is the special object of the present work to combat those errors which derive their source from a vicious empiricism and from imperfect inductions. The higher enjoyments yielded by the study of nature depend upon the correctness and the depth of our views, and upon the extent of the sub- jects that may be comprehended in a single glance. Increased mental cultivation has given rise, in all classes of society, to an increased desire of embellishing life by augmenting the mass of ideas, and by multiplying means for their generalization ; and this sentiment fully refutes the vague accusations ad- vanced against the age in which we live, showing that other interests, besides the material wants of life, occupy the minds of men. It is almost with reluctance that I am about to speak of a sentiment, which appears to arise from narrow-minded views, or from a certain weak and morbid sentimentality,—I allude to the fear entertained by some persons, that nature may by degrees lose a portion of the charm and magic of her power, as we learn more and more how to unveil her secrets, com- prehend the mechanism of the movements of the heavenly bodies, and estimate numerically the intensity of natural forces. It is true that, properly speaking, the forces of nature can only exercise a magical power over us, as long as their action is shrouded in mystery and darkness, and does not admit of being classed among the conditions with which experience has made us acquainted. The effect of such a power is, therefore, to excite the imagination, but that, assur- edly, is not the faculty of mind we would evoke to preside over the laborious and elaborate observations by which we strive to attain to a knowledge of the greatness and excellence of the laws of the universe. The astronomer who, by the aid of the heliometer or a double-refracting prism,* determines the diameter of pla- * Arago’s ocular micrometer, a happy improvement upon Rochon’s prismatic or double-refraction micrometer. See M. Mathieu’s note in Délambre’s Histoire de l Astronomie au dix-huitiéme Siecle, 1827. INTRODUCTION. 19 netary bodies, who measures patiently, year after year, the meridian altitude and the relative distances of stars, or who seeks a telescopic comet in a group of nebule, does not feel his imagination more excited—and this is the very guarantee of the precision of his labours—than the botanist who counts the divisions of the calyx, or the number of stamens in a flower, or examines the connected or the separate teeth of the eristoma surrounding the capsule of a moss. Yet the multi- plied angular measurements, on the one hand, and the detail of organic relations on the other, alike aid in preparing the way for the attainment of higher views of the laws of the universe. We must not confound the disposition of mind in the observer at the time he is pursuing his labours, with the ulte- rior greatness of the views resulting from investigation and the exercise of thought. The physical philosopher measures with admirable sagacity the waves of light of unequal length which by interference mutually strengthen or destroy each other, even with respect to their chemical actions: the astronomer, armed with powerful telescopes, penetrates the regions of space, contemplates, on the extremest confines ot our solar system, the satellites of Uranus, or decomposes faintly sparkling points into double stars differing in colour. The botanist discovers the constancy of the gyratory motion of the chara in the greater number of vegetable cells, and recog- nises in the genera and natural families of plants the intimate relations of organic forms. The vault of heaven, studded with nebule and stars, and the rich vegetable mantle that covers the soil in the climate of palms, cannot surely fail to produce on the minds of these laborious observers of nature, an impression more imposing and more worthy of the majesty of creation, than on those who are unaccustomed to investi- gate the great mutual relations of phenomena. I cannot, therefore, agree with Burke when he says, “it is our igno- rance of natural things that causes all our admiration, and chiefly excites our passions.” _ . Whilst the illusion of the senses would make the stars sta- tionary in the yault of heaven, astronomy by her aspiring labours has assigned indefinite bounds to space ; and if she have set limits to the great nebula to which our solar system belongs, it has only been to show us in those remote regions c 2 20 COSMOS. of space, which appear to expand in proportion to the increase of our optic powers, islet on islet of scattered nebule. The feeling of the sublime, so far as it arises from a contemplation of the distance of the stars, of their greatness and physical extent, reflects itself in the feeling of the infinite, which belongs to another sphere of ideas included in the domain of mind. ‘The solemn and imposing impressions excited by this sentiment, are owing to the combination of which we haye spoken, and to the analogous character of the enjoyment and emotions awakened in us, whether we float on the surface of the great deep, stand on some lonely mountain summit enveloped in the half-transparent vapoury veil of the atmo- sphere, or by the aid of powerful optical instruments scam the regions of space, and see the remote nebulous mass resolve itself into worlds of stars. The mere accumulation of unconnected observations of details, devoid of generalization of ideas, may doubtlessly have tended to create and foster the deeply-rooted prejudice, that the study of the exact sciences must necessarily chill the feelings, and diminish the nobler enjoyments, attendant upon a contemplation of nature.. Those who still cherish such erroneous views in the present age, and amid the progress of public opinion, and the advancement of all branches of know- edge, fail in duly appreciating the value of every enlarge- ment of the sphere of intellect, and the importance of the detail of isolated facts in leading us on to general results. The fear of sacrificing the free enjoyment of nature, under the influence of scientific reasoning, is often associated with an apprehension, that every mind may not be capable of grasping the truths of the philosophy of nature. It is certainly true that in the midst of the universal fluctuation of phenomena ‘and vital forees—in that inextricable network of organisms by turns developed and destroyed—each step that we make in the more intimate knowledge of nature, leads us to the entrance of new labyrinths ; but the excitement produced by a presentiment of discovery, the vague intuition of the mys- teries to be unfolded, and the multiplicity of the paths before us, all tend to stimulate the exercise of thought im every stage of knowledge. ‘The discovery of each separate law of nature leads to the establishment of some other more general }» law, or at least indicates to the intelligent observer its existe INTRODUCTION. 91 ence. Nature, as a celebrated physiologist* has defined it, and as the word was interpreted by the Greeks and Romans, is “that which is ever growing and ever unfolding itself in new forms.” The series of organic types becomes extended or perfected, in proportion as hitherto unknown regions are laid open to eur view by the labours and researches of travellers and observers; as living organisms are compared with those which have disappeared in the great revolutions of our planet; and as microscopes are made more perfect and are more extensively and efficiently employed. In the midst of this immense variety, and this periodic transformation of animal and vegetable productions, we see incessantly revealed the primordial mystery of all organic development, that same great problem of metamorphosis which Géthe has treated \ with more than common sagacity, and to the solution of which man is urged by his desire of reducing vital forms to the smallest number of fundamental types. As men contem- plate the riches of nature, and see the mass of observations incessantly increasing before them, they become impressed with the intimate conviction that the surface and the interior of the earth, the depths of the ocean, and the regions of air will still, when thousands and thousands of years have passed away, open to the scientific observer untrodden paths of dis- coyery. The regret of Alexander cannot be applied to the progress of observation and intelligence.t General consi- derations, whether they treat of the agglomeration of matter in the heavenly bodies, or of the geographical distribution of terrestrial organisms, are not only in themselves more attrac- tive than special studies, but they also afford superior advan- tages to those who are unable to deyote much time to occupa- tions of this nature. The different branches of the study of natural history are only accessible in certain positions of social life, and do not at every season and in every climate present hke enjoyments. Thus, in the dreary regions of the north, man is deprived for a long period of the year of the spectacle presented by the activity of the productive forces of organic nature; and if the mind be directed to one sole class Beata. Von den Urtheilen des Knochen und Schalen Geristes, t Plut., in Vita Alex. Magni, cap. 7. ’ 22 COSMOS. of objects, the most animated narratives of voyages in distant lands will fail to interest and attract us, if they do not touch upon the subjects to which we are most partial. | As the history of nations—if it were always able to trace events to their true causes— might solve the ever-recurring enigma of the oscillations experienced by the alternately pro- gressive and retrograde moyement of human society, so might also the physical description of the world, the science of the Cosmos, if it were grasped by a powerful intellect, and based upon a knowledge of all the results of discovery up to a given period, succeed in dispelling a portion of the contradic- tions, which, at first sight, appear to arise from the complica- tion of phenomena and the multitude of the perturbations simultaneously manifested. The knowledge of the laws of nature, whether we can trace them in the alternate ebb and flow of the ocean, in the measured path of comets, or in the mutual attractions of multiple stars, alike increases our sense of the calm of nature, whilst the chimera so long cherished by the human mind in its early and intuitive contemplations, the belief in a “ discord of the elements,” seems gradually to vanish in proportion as science extends her empire. General views lead us habitually to consider each organism as a part of the entire creation, and to recognise in the plant or the animal, not merely an isolated species, but a form linked in the chain of being to other forms either living or extinct. They aid us in comprehending the relations that exist between the most recent discoveries and those which have prepared the way for them. Although fixed to one point of space, we eagerly grasp at a knowle of that which has been observed in different and far distant regions. We delight in tracking the course of the bold mariner through seas of polar ice, or in following him to the summit of that volcano of the antarctic pole, whose fires may be seen from afar, even at mid-day... It is by an acquaintance with the results of distant voyages, that we may learn to comprehend some of the marvels of terrestrial magnetism, and be thus led to appre- ciate the importance of the establishments of the numerous observatories, which in the present day, cover both-hemispheres, and are designed to note the simultaneous occurrence of perturbations, and the frequency and duration of magnetié storms. INTRODUCTION. 93 ‘Let me be permitted here to touch upon a few points connected with discoveries, whose importance can only be estimated by those who have devoted themselves to the study of the physical sciences generally. Examples chosen from among the phenomena to which special attention has been directed in recent times, will throw additional light upon the preceding considerations. Without a preliminary knowledge of the orbits of comets we should be unable duly to appre- ciate the importance attached to the discovery of one of these bodies, whose elliptical orbit is included in the narrow limits of our solar system, and which has revealed the existence of an ethereal fluid, tending to diminish its centrifugal force and the period of its revolution. The superficial half-knowledge, so characteristic of the present day, which leads to the introduction of vaguely com- prehended scientific views into general conversation, also gives rise, under.various forms, to the expression of alarm at the supposed danger of a collision between the celestial bodies, or of disturbance in the climatic relations of our globe. These phantoms of the imagination are so much the more injurious as they derive their source from dogmatic pretensions to true - science. The history of the atmosphere, and of the annual variations of its temperature, extends already sufficiently far back to show the recurrence of slight disturbances in the mean temperature of any given place, and thus affords sufficient gua- rantee against the exaggerated apprehension of a general and progressive deterioration of the climates of Europe. Encke’s comet, which is one of the three interior comets, completes its course in 1,200 days, but from the form and position of its orbit it is as little dangerous to the earth as Halley’s great comet, whose revolution is not completed in less than seventy-six years, (and which appeared less brilliant in 1835 than it had done in 1759;) the interior comet of Biela intersects the earth’s orbit, it is true, but it can only approach our globe when its proximity to the sun coincides with our winter solstice. The quantity of heat received by a planet, and whose unequal distribution determines the meteorological variations of its atmosphere, depends alike upon the light-engendering force of the sun, that is to say, upon the condition of its gaseous coverings, and upon the relative position of the pianet and the central body. 24 COSMOS. There are variations, it is true, which in obedience to the laws of universal gravitation, affect the form of the earth’s orbit, and the inclination of the ecliptic, that is, the angle which the axis of the earth makes with the plane of its orbit; but these periodical variations are so slow, and are restricted within such narrow limits, that their thermic effects would hardly be appreciable by our instruments in many thousands of years. ‘The astronomical causes of a refrigeration of our globe, and of the diminution of moisture at its surface, and the nature and frequency of certain epidemics—phenomena which are often discussed in the present day according to the benighted views of the middle ages—ought to be considered as beyond the range of our experience in physics and chemistry. Physical astronomy presents us with other phenomena, which cannot be fully comprehended in all their vastness without a previous acquirement of general views regarding the forces that govern the universe. Such, for instance, are the innumerable double stars, or rather suns, which revolve round one common centre of gravity, and thus reveal in distant worlds the existence of the Newtonian law; the larger or smaller number of spots upon the sun, that is to. say, the openings formed through the luminous and opaque atmosphere surrounding the solid nucleus; and the regular appearance, about the 13th of November, and the 11th of August, of shooting stars, which probably form part of a belt of asteroids, intersecting the earth’s orbit, and moving with planetary velocity. _ Descending from the celestial regions to the earth, we would fain inquire into the relations that exist between the oscillations of the pendulum in air (the theory of which has been perfected by Bessel), and the density of our planet ; and how the pendulum, acting the part of a plummet, can, to a certain extent, throw light upon the geological constitution of strata at great depths? By means of this instrument we are enabled to trace the striking analogy which exists between the formation of the granular rocks composing the lava cur- rents ejected from active volcanoes, and those endogenous masses of granite, porphyry, and serpentine, which, issuing from the interior of the earth have broken, as eruptive rocks, through the secondary strata, and modified them by contact, either in rendering them harder by the introduction of silex, INTRODUCTION 95 or reducing them into dolomite ; or finally by inducing within them the formation of crystals of the most varied composition. The elevation of sporadic islands, of domes of trachyte, and cones of basalt, by the elastic forces emanating from the fluid interior of our globe, has led one of the first geologists of the age, Leopold von Buch, to the theory of the elevation o1 continents, and of mountain chains generally. This action of subterranean forces in breaking through, and elevating strata of sedimentary rocks, of which the coast of Chili, in conse- quence of a great earthquake, furnished a recent example, leads to the assumption, that the pelagic shells found by M. Bonpland and myself on the ridge of the Andes, at an eleyation of more than 15,000 English feet, may have been conveyed to so extraordinary a position, not by a rising of the ocean, but by the agency of volcanic forces capable of ele- yating into ridges the softened crust of the earth. I apply the term volcanic, in the widest sense of the word, to every action exercised by the interior of a planet on its external crust. The surface of our globe, and that of the moon, manifest traces of this action, which in the former, at least, has varied during the course of ages. Those, who are ignorant of the fact, that the internal heat of the earth increases so ra- pidly with the increase of depth, that granite is in a state of fusion about twenty or thirty geographical miles below the surface,* cannot have a clear conception of the causes, and the simultaneous occurrence of volcanic eruptions at places widely removed from one another, or of the extent and inter- section of circles of commotion in earthquakes, or of the uniformity of temperature, and equality of chemical com- position observed in thermal springs during a long course of years. The quantity of heat peculiar to a planet is, however, a matter of such importance,—being the result of its primitive condensation, and yarying according to the nature and duration of the radiation,—that the study of this subject may * The determinations usually given of the point of fusion are in general much too high for refracting substances. According to the very accurate researches of Mitscherlich, the melting point of granite can hardly exceed 2372° F. [Dr. Mantell states in The Wonders of Geology, 1848, vol. i. page 34, that this increase of temperature amounts to 1° of Fahrenheit for every 54 feet of vertical depth.]—7r. 26 COSMOS. throw some degree of light on the history of the atmosphere, and the distribution of the organic bodies imbedded in the solid crust of the earth. This study enables us to understand how a tropical temperature, independent of latitude (that is, of the distance from the poles), may have been produced by deep fissures remaining open, and exhaling heat from the interior of the globe, at a period when the earth’s crust was still furrowed and rent, and only in a state of semi-solidifi- cation; and a primordial condition is thus revealed to us, in which the temperature of the atmosphere, and climates: generally were owing rather to a liberation of caloric and of different gaseous emanations, (that is to. say, rather to the energetic re-action of the interior on the exterior,) than to the position of the earth with respect to the central body, the sun. The cold regions of the earth contain, deposited in sedi- mentary strata, the products of tropical climates; thus, in the coal formations, we find the trunks of palms standing upright amid conifere, tree ferns, goniatites and fishes, having rhomboidal osseous scales;* in the Jura lime- stone colossal skeletons of crocodiles, plesiosauri, planulites, and stems of the cycades; in the chalk formations, small polythalamia and bryozoa, whose species still exist in our seas; in tripoli, or polishing slate, in the semi-opal and the farina-like opal or mountain meal, agglomerations of siliceous. infusoria which have been brought to light by the powerful microscope of Ehrenberg}; and lastly, in transported soils, * See the classical work on the fishes of the old world by Agassiz’ Rech. sur les Poissons Fossiles, 1834, vol.i. p. 333; vol. ii. pp. 3, 28, 34, App. p. 6. The whole genus of Amblypterus, Ag. nearly allied to Pa- lgzoniscus (called also Palzeothrissum) lies buried beneath the Jura forma~- tions in the old carbonferous strata. Scales which, in some fishes, as in the family of Lepidoides (order of Ganoides), are formed like teeth, and covered in certain parts with enamel, belong, after the Placoides, to the oldest forms of fossil fishes ; their living representatives are still found intwo’ genera, the Bichir of the Nile and Senegal, and the Lepidosteus of Ohio. + [The polishing slate of Bilin is stated by M. Ehrenberg to form a series of strata fourteen feet in thickness, entirely made up of the siliceous shells of Gailionelle, of such extreme minuteness, that a cubic inch of the stone contains forty-one thousand millions! The Bergmehl (moun- tain-meal or fossil farina), of San Fiora, in Tuscany, is one mass of animalculites. See the interesting work of G. A. Mantell, On the Medals of Creation, vol. i. p. 223.]—Tr. , ; INTRODUCTION. 3% and in certain caves, the bones of elephants, hyenas, and lions. An intimate acquaintance with the physical pheno- mena of the universe leads us to regard the products of warm latitudes that are thus found in a fossil condition in northern regions, not merely as incentives to barren curiosity, but as subjects awakening deep ~eflection, and opening new sources of study. The number and the variety of the objects I have ailuded to, give rise to the question whether general considerations of physical phenomena can be made sufficiently clear to per- sons, who have not acquired a detailed and special know- ledge of descriptive natural history, geology, or mathematical astronomy? I think we ought to distinguish here between him, whose task it is to collect the individual details of various observations, and study the mutual relations existing amongst them, and him to whom these relations are to be revealed, under the form of general results. The former should be acquainted with the specialities of phenomena, that he may arrive at a generalization of ideas as the result, at least in part, of his own observations, experiments, and calculations. It cannot be denied, that where there is an absence of positive knowledge of physical phenomena, the gereral results which impart so great a charm to the study of nature cannot all be made equally clear and intelligible to the reader, but still I venture to hope, that in the work which I am now preparing on the physical laws of the universe, the greater part of the facts advanced can be made manifest without the necessity of appealing to fundamental views and principles. The picture of nature thus drawn, notwithstanding the want of distinctness of some of its out- lines, will not be the less able to enrich the intellect, enlarge the sphere of ideas, and nourish and vivify the imagination. There is, perhaps, some truth in the accusation advanced against many German scientific works, that they lessen the value of general views by an accumulation of detail; and do | not sufficiently distinguishing between those great results which form, as it were, the beacon lights of science, and the long series of means by which they have been attained. This method of treating scientific subjects led the most illustrious of our poets* to exclaim with impatience—‘'The Germans * Gothe, in Die Aphorismen tber Naturwissenschaft, bd. 1.) 8. 155. | (Werke kleine Ausgabe, von 1833.) 28 COSMOS. have the art of making science inaccessible.” An edifice cannot produce a striking effect until the scaffolding is re- moved, that had of necessity been used during its erection. Thus the uniformity of figure observed in the distribution of continental masses, which all terminate towards the south in a pyramidal form, and expand towards the north (a law that determines the nature of climates, the direction of currents in the ocean and the atmosphere, and the transition of certain types of tropical vegetation towards the southern temperate zone), may be clearly apprehended without any knowledge of the geodesical and astronomical operations by means of which these pyramidal forms of continents have been determined. In like manner, physical geography teaches us by how many leagues the equatorial axis exceeds the polar axis of the globe ; and shows us the mean equality of the flattening of the two hemispheres, without entailing on us the necessity of giving the detail of the measurement of the degrees in the meridian, or the observations on the pendulum, which have led us to know that the true figure of our globe is not exactly that of a regular ellipsoid of revolution, and that this irregularity is reflected in the corresponding irregularity of the movements of the moon. The views of comparative geography have oeen specially enlarged by that admirable work, Hrdkunde im Verhaltniss zur Natur und zur Geschichte, in which Carl Ritter so ably delineates the physiognomy of our globe, and shows the influence of its external configuration on the physical phe- nomena on its surface, on the migrations, laws, and manners, of nations, and on all the principal historical events enacted upon the face of the earth. | France possesses an immortal work, L’Hzposition du Systeme du Monde, in which the author has combined the results of the highest astronomical and mathematical labours, and presented them to his readers free from all processes of demonstration. ‘The structure of the heavens is here reduced to the simple solution of a great problem in mechanics; yet Laplace’s work has never yet been accused of incompleteness and want of profundity. The distinction between dissimilar subjects, and the sepa- ration of the general from the special are not only conducive to the attainment of perspicuity in the composition of a yhysical history of the universe, but are also the means by INTRODUCTION. 29 which a character of greater elevation may be imparted to the study of nature. By the suppression of alli unnecessary detail, the great masses are better seen, and the reasoning faculty is enabled to grasp all that might otherwise escape the limited range of the senses. The exposition of general results has, it must be owned, been singularly facilitated by the happy revolution experienced since the close of the last century, in the condition of all the special sciences, more particularly of geology, chemistry, and descriptive natural history. In proportion as laws admit of more general application, and as sciences mutually enrich each other, and by their extension become connected together in more numerous and more intimate relations, the develop- ment of general truths may be given with conciseness devoid of superficiality. On being first examined, all phenomena appear to be isolated, and it is only by the result of a multi- plicity of observations, combined by reason, that we are able to trace the mutual relations existing between them. If, how- ever, in the present age, which is so strongly characterised by a brilliant course of scientific discoveries, we perceive a want of connection in the phenomena of certain sciences, we may anticipate the revelation of new facts, whose importance will probably be commensurate with the attention directed to these branches of study. Expectations of this nature may be entertained with regard to meteorology, several parts of optics, and to radiating heat, and electro-magnetism, since the admirable discoveries of Melloni and Faraday. A fertile field is here opened to discovery, although the voltaic pile has already taught us the intimate connection existing between electric, magnetic, and chemical phenomena. Who will venture to affirm that we have any precise knowledge, in the present day, of that part of the atmosphere which is not | oxygen, or that thousands of gaseous substances affecting our | organs may not be mixed with the nitrogen, or finally, that we have even discovered the whole number of the forces which pervade the universe ? It is not the purpose of this essay on the physical history of the world to reduce all sensible phenomena to a small number of abstract principles, based on reason only. The physical history of the universe, whose exposition I attempt to deve- lope, does not pretend to rise to the perilous abstractions of a 30 COSMOS. purely rational science of nature, and is simply a physical geography, combined with a description of the regions of space and the bodies occupying them. Devoid of the profoundness of ,. : ¢ _a purely speculative philosophy, my essay on the Cosmos treats — of the contemplation of the universe, and is based upon a_ rational empiricism, that is to say, upon the results of the facts registered by science, and tested by the operations of the intellect. It is within these limits alone that the work, which — I now yenture to undertake, appertains to the sphere of labour, to which I have devoted myself throughout the course of my long scientific career. This path of enquiry is not unknown to me, although it may be pursued by others with greater success. The unity which I seek to attain in the development of the great phenomena of the universe, is analogous to that which historical composition is capable of acquiring. All points relating to the accidental indi- -vidualities, and the essential variations of the actual, whether in the form and arrangement of natural objects in the struggle of man against the elements, or of nations against nations, do not admit of being based only on a rational foundation —that is to say, of being deduced from ideas alone. It seems to me that a like degree of empiricism attaches to the Description of the Universe and to Civil History ; but in reflecting upon physical phenomena and eyents, and tracing their causes by the process of reason, we become more and more convinced of the truth of the ancient doctrine, that the forces inherent in matter, and those which govern the moral world, exercise their action under the control of primordial necessity, and in accordance with movements occurring periodi- cally after longer or shorter intervals. | It is this necessity, this occult but permanent connection, this periodical recurrence in the progressive doyelopment of forms, phenomena, and events, which constitute nature, obedi- ent to the first impulse imparted to it. Physics, as the term signifies, is limited to the explanation of the phenomena of the material world by the properties of matter. The ultimate ‘object of the expérimental sciences is, therefore, to discover laws, and to trace their progressive generalization. All that } i} exceeds this goes beyond the province of the physical descrip- _ tion of the universe, and appertains to a range of higher . speculative views. INTRODUCTION. 81 Emanuel Kant, one of the few philosophers who have escaped the imputation of impiety, has defined with rare sagacity the limits of physical explanations, in his celebrated essay On the Theory and Structure of the Heavens, published at Kénigsberg, in 1755. . The study of a science that promises to lead us through the vast range of creation may be compared to a journey in a far distant land. Before we set forth we consider, and often with distrust, our own strength and that of the guide we have chosen. But the apprehensions which have originated in the abundance and the difficulties attached to the subjects we would embrace, recede from view as we remember that with the increase of observations in the present day, there has also arisen a more intimate knowledge of the connection existing among all phenomena. It has not unfrequently happened, that the researches made at remote distances have often and unexpectedly thrown light upon subjects which had long resisted the attempts made to explain them, within the narrow limits of our own sphere of observation. Organic forms that had long remained isolated, both in the animal and vegetable kingdom, have been connected by the discovery of inter- | mediate links or stages of transition. The geography of beings endowed with life attains completeness, as we see the species, genera, and entire families belonging to one hemi- sphere, reflected, as it were, in analogous animal and vegetable forms in the opposite hemisphere. ‘These are, so to speak, the equivalents which mutually personate and replace one another in the great series of organisms. These connecting links and | stages of transition may be traced, alternately, in a deficiency or an excess of development of certain parts, in the mode of junc- tion of distinct organs, in the differences in the balance of forces, or in a resemblance to intermediate forms which are not per- manent, but merely characteristic of certain phases of normal development. Passing from the consideration of beings en- dowed with life to that of inorganic bodies, we find many striking illustrations of the high state of advancement to which modern geology has attained. We thus see, according to the grand views of Elie de Beaumont, how chains of moun- tains dividing different climates ‘and floras and different races of men, reveal to us their relative age, both by the character of the sedimentary strata they have uplifted, and by the diree- $2 COSMOS. tions which they follow over the long fissures with which the earth’s crust is furrowed. Relations of super-position of trachyte and of syenitic porphyry, of diorite and of serpen- tine, which remain doubtful when considered in the auriferous soil of Hungary, in the rich platinum districts of the Oural, and on the south-western declivity of the Siberian Altai, are elucidated by the observations that have been made on the plateaux of Mexico and Antioquia, and in the unhealthy ravines of Choco. The most important facts on which the physical history of the world has been based in modern times, have not been accumulated by chance. It has at length been fully acknowledged, and the conviction is characteristic of the age, that the narratives of distant travels, too long occupied in the mere recital of hazardous adventures, can only be made a source of instruction, where the traveller is acquainted with the condition of the science he would enlarge, and is guided by reason in his researches It is by this tendency to generalization, which is only dangerous in its abuse, that a great portion of the physical knowledge already acquired may be made the common pro- perty of all classes of society; but in order to render the | instruction imparted by these means commensurate with the importance of the subject, it is desirable to deviate as widel as possible from the imperfect compilations designated, till the close of the eighteenth century, by the inappropriate term of popular knowledge. I take pleasure in persuading myself that scientific subjects may be treated of in language at once dignified, grave and animated, and that those who are re- stricted within the circumscribed limits of ordinary life, and have long remained strangers to an intimate communion with nature, may thus have opened to them one of the richest sources of enjoyment by which the mind is invigorated by the acquisition of new ideas. Communion with nature awakens within us perceptive faculties that had long lain dormant ; and we thus comprehend at a single glance the influence exercised by physical discoveries on the enlargement of the sphere of intellect, and perceive how a judicious application of mechanics, chemistry, and other sciences may be made conducive to national prosperity. A more accurate knowledge of the connection of physical phenomena will also tend to remoye the prevalent error that INTRODUCTION. 83 all branches of natural science are not equally important in relation to general cultivation and industrial progress. An arbitrary distinction is frequently made between the various degrees of importance appertaining to mathematical sciences, to the study of organised beings, the knowledge of electro- magnetism, and investigations of the general properties of matter in its different conditions of molecular aggregation ; and it is not uncommon presumptuously to affix a supposed stigma upon researches of this nature, by terming them “purely theoretical,’ forgetting, although the fact has been long attested, that in the observation of a phenomenon, which at first sight appears to be wholly isolated, may be concealed the germ of a great discovery. When Aloysio Galvani first stimulated the nervous fibre by the accidental contact of two heterogeneous metals, his contemporaries could never have anticipated, that the action of the voltaic pile would discover to us, in the alkalies, metals of a silvery lustre, so light as to swim on water, and eminently inflammable ; or that it would become a powerful instrument of chemical analysis, and at the same time a thermoscope, and a magnet. When Huyghens first observed, in 1678, the phenomenon of the polarization of light, exhibited in the difference between the two rays into which a pencil of light divides itself in passing through a doubly refracting crystal, it could not have been foreseen, that a century and a half later the great philosopher, Arago, would by his discovery of chromatic polarization, be led to discern, by means of a small fragment of Iceland spar, whether solar light emanates from a solid body, or a gaseous covering ; ‘or whether comets transmit light directly, or merely by re- flection.* An equal appreciation of all branches of the mathematical, physical and natural sciences, is a special requirement of the present age, in which the material wealth and the growing prosperity of nations are principaily based upon a more en- lightened employment of the products and forces of nature. The most superficial giance at the present condition of Europe shows that a diminution, or even a total annihilation of national prosperity, must be the award of those states who * Arago’s Discoveries in the year 1811.— Delambre’s Histoire de l’ Ast., p. 652. (Passage already quoted.) D $4 COSMOS. shrink with slothful indifference from the great struggle of rival nations in the career of the industrial arts. I¢ is with nations as with nature, which, according to a happy ex- pression of Gdéthe,* “knows no pause in progress and development, and attaches her eurse on all inaction.” The propagation of an earnest and sound knowledge of science can therefore alone avert the dangersof which I have spoken. Man_ cannot act upon nature, or appropriate her forces to his own use, without comprehending their fnll extent, and having an intimate acquaintance with the laws of the physical world. Bacon has said that, m human societies, knowledge is power. Both must rise and sink together. But the knowledge that results from the free action of thought, is at once the delight and the indestructible prerogative of man; and in forming part of the wealth of mankind, it not unfrequently serves as a substitute for the natural riches, which are but sparingly scattered over the earth. Those states which take no active part in the general industrial movement, in the choice and preparation of natural substances, or in the application of mechanics and chemistry, and among whom this activity is not appreciated by all classes of society, will infallibly see their prosperity diminish in proportion as neighbouring coun-’ tries become strengthened and invigorated under the genial influence of arts and sciences. ee As in nobler spheres of thought and sentiment, in philo- | sophy, poetry, and the fine arts, the object at which we aim ought to be an inward one—an ennoblement of the intellect— so ought we likewise, in our pursuit of science, to strive after a knowledge of the laws and the principles of unity that pervade the vital forces of the universe; and it is by such a course that physical studies may be made subservient to the progress of industry, which is a conquest of mind over matter. By a happy connection of causes and effects, we often see the useful linked to the beautiful and the exalted. ‘The improve- ment of agriculture in the hands of free men, and on pro- perties of a moderate extent—the flourishing state of the mechanical arts freed from the trammels of municipal restric- tions-——the increased impetus imparted to commerce by the * Gtthe, in Die Aphorismen téber Naturwissenschaft.—Werke, bd, i. 8. 4. \ ie INTRODUCTION. 3& multiplied means of contact of nations with each other—are. all brilliant results of the intellectual progress of mankind, and of the amelioration of political institutions, in which this progress is reflected. The picture presented by modern i ought to convinee those who are tardy in awakening to the truth of the lesson it teaches. Nor let it be feared, that the marked predilection for the study of nature, and for industrial progress, which is so charac- teristic of the present age, should necessarily have a tendency to retard the noble exertions of the intellect in the domains of philosophy, classical history, and antiquity ; or to deprive the arts by which life is embellished of the vivifying breath of imagination. Where all the germs of civilisation are developed beneath the egis of free institutions and wise legislation, there is no cause for apprehending that any one branch of knowledge should be cultivated to the prejudice of others. All afford the state precious fruits, whether they yield nourishment to man and constitute his physical wealth, or whether, more permanent in their nature, they transmit in the works of mind the glory of nations to remotest posterity.. The Spartans, notwithstanding their Doric austerity, prayed the gods to grant them “ the beautiful with the good.” * I will no longer dwell upon the considerations of the infiu- ence exercised by the mathematical and physical sciences on all that appertains to the material wants of social life; for the yast extent of the course on which I am entering forbids me to insist further upon the utility of these applications. Accus- tomed to distant excursions, I may, perhaps, have erred in deseribing the path before us as more smooth and pleasant than it really is, for such is wont to be the practice of those who delight in guiding others to the summits of lofty moun- tains: they praise the view even when great part of the distant plains lie hidden by clouds, knowing that this half- transparent vapoury veil imparts to the scene a certain charm the power exercised by the imagination over the domain of the senses. In like manner, from the height occupied by the physical history of the world, all parts of the horizon will not appear equally clear and well-defined. This indistinct- * Pseudo-Plato.—Alcib. xi. p. 184, ed. Steph.; Plut., Institute Laconica, p. 253, ed, Hutten. ‘é D2 36 COSMOS. ness will not, however, be wholly owing to the present imper- fect state of some of the sciences, but in part, likewise, to the unskilfulness of the guide who has imprudently ventured to ascend these lofty summits. The object of this introductory notice is not, however, solely to draw attention to the importance and greatness of the physical history of the universe, for in the present day these are too well understood to be contested, but likewise to prove how, without detriment to the stability of special studies, we may be enabled to generalize our ideas by concentrating them in one common focus, and thus arrive at a point of view from which all the organisms and forces of nature may be seen as one living active whole, animated by one sole impulse. “Nature,” as Schelling remarks in his poetic discourse on art, ‘‘ is not an inert mass ; and to him, who can comprehend her vast sublimity, she reveals herself as the creative force of the universe—before all time, eternal, ever active, she calls to life all things, whether perishable or imperishable.” By uniting, under one point of view, both the phenomena of our own globe and those presented in the regions of space, we embrace the limits of the science of the Cosmos, and convert | the physical history of the globe into the physical history of the universe ; the one term being modelled upon that of the other. This science of the Cosmos is not, however, to be regarded as a mere encyclopedic aggregation of the most important and general results that have been collected together from special branches of knowledge. These results are nothing more than the materials for a vast edifice, and their combination cannot constitute the physical history of the world, whose exalted part it is to show the simultaneous action and the connecting links of the forces which pervade the universe. The distri- bution of organic types in different climates and at different elevations—that is to say, the geography of plants and animals —differs as widely from botany and descriptive zoology as geology does. from mineralogy, properly so called. The physical history of the universe must not, therefore, be con- founded with the Encyclopedias of the Natural Sciences, as they have hitherto been compiled, and whose title is as vague as their limits are ill-defined. In the work before us, partial facts will be considered only in relation to the whole. The higher the point of view the greater is the necessity for a syste- INTRODUCTION. 37 matic mode of treating the subject in language at once ani- mated and picturesque. But thought and language have ever been most intimately allied. If language, by its originality of structure, and its native richness, can, in its delineations, interpret thought with grace and clearness, and if, by its happy flexibility, it can paint with vivid truthfulness the objects of the external world, it reacts at the same time upon thought, and animates it, as it were, with the breath of life. It is this mutual re-action which makes words more than mere signs and forms of thought; and the beneficent influence of a language is most strikingly manifested on its native soil, where it has sprung sponta- neously from the minds of the people, whose character it embodies. Proud of a country that seeks to concentrate her strength in intellectual unity, the writer recalls with delight the advantages he has enjoyed in being permitted to express his thoughts in his native language; and truly happy is he, who, in attempting to give a lucid exposition of the great pheno- mena of the universe, is able to draw from the depths of a language, which through the free exercise of thought, and by the effusions of creative fancy, has for centuries past exercised so powerful an influence over the destinies of man. LIMITS AND METHOD OF EXPOSITION OF THE PHYSICAI DESCRIPTION OF THE UNIVERSE. I HAVE endeavoured, in the preceding part of my*work, to explain and illustrate by various examples, how the enjoy- ments presented by the aspect of nature, varying as they do in the sources from whence they flow, may be multiplied and ennobled by an acquaintance with the connection of pheno- mena and the laws by which they are regulated. It remains, then, for me to examine the spirit of the method in which the exposition of the physical description of the universe should be conducted, and to indicate the limits of this science, in accord- ance with the views I have acquired in the course of my studies and travels in various parts of the earth. I trust I may flatter myself with a hope that a treatise of this nature 38 ) \COsiros. will justify ‘the title I have ventured to adopt for: my work, and exonerate me from the reproach. of a presumption that would be doubly reprehensible in a scientific discussion. Before entermg upon the delineation of the partial pheno- mena which are found to be distributed m various groups, I would consider a few general questions intimately connected together, and bearing upon the nature of our knowledge of the external world and its different relations, in all epochs of history and in all phases of mtelleetual advancement. Under this head will be comprised the following considerations :— ~ 1. The precise limits of the physical description of the uni- -verse, considered as a distinct science. 2. A brief enumeration of the totality of natural : mena, presented under the form of a general delineation of nature. 3. The influence of the external world on the imagination and feelings, which has acted in modern times as a powerful impulse towards the study of natural science, by giving ani- mation to the description of distant regions and to the deline-— ation of natural scenery, as far as it is characterised by vege- table physiognomy, and by the cultivation of exotic plants, ) and their arrangement in well-contrasted groups. 4, The history of the contemplation of nature, or the pro- gressive development of the idea of the Cosmos, considered with reference to the historical and geographical facts that have led to the discovery of the connection of phenomena. _. The higher the point of view from which natural phenomena may be considered, the more necessary it is to circumscribe the science within its just limits, and to peso ane it from all other analogous or auxiliary studies. _ Physical cosmography is founded on the contemplation of all created things,—ail that exists in space, whether as sub- stances or forces,—that is, all the material beings that eon- stitute the universe. The science which I would attempt to define, presents itself therefore to man as the inhabitant of the earth, under a twofold form—as the earth itself, and the regions _of space. It is with a view of showing the actual character and the independence of the study of physical cosmography, and at the same time indicating the nature of its relations to general physics, descriptive natural history, geology, and com- parative geography, that I will pause for a few moments to INTRODUCTION, 39 consider that portion.of the science of the Cosmos which con- eerns the earth. As the history of philosophy does not con- sist of a mere material enumeration of the philosophical views entertained in different ages, neither should the physical description of the universe be a simple encyclopedic compila- tion of the sciences we have enumerated. The difficulty of defining the limits of intimately-connected studies has been increased, because for centuries it has been customary to designate various branches of empirical knowledge by terms which admit either of too wide or too limited a definition of ‘the ideas which they were intended to convey, and are, besides, objectionable from having had a different significa- tion in those classical languages of antiquity from which they have been borrowed. ‘The terms physiology, physics, natural history, geology, and geography, arose, and were common! used, long before clear ideas were entertained of the diversity ‘of objects embraced by these sciences, and consequently of ‘their reciprocal limitation. Such is the influence of long chabit upon language, that by one of the nations of Europe -most advanced im civilisation the word “ physic”’ is applied to medicine, whilst in a society of justly deserved universal _reputation, technical chemistry, geology, and astronomy, (purely experimental sciences,) are comprised under the head of * Philosophical Transactions.”’ An attempt has often been made, and almost always in _yain, to substitute new and more appropriate terms for these -ancient designations, which, notwithstanding their undoubted “vagueness, are now generally understood. These changes have been proposed, for the most part, by those who have occupied themselves with the general classification of the various branches of knowledge, from the first appearance of the great encyclopedia (Margarita Plulosophica) of Gregory Reisch,* prior of the Chartreuse at Friburg, towards the close * The Margarita Philosophica of Gregory Reisch, Prior of the Char- _treuse at Friburg, first appeared under the following title: AZpitome omnis | Philosophie, alias Margarita Philosophica, tractans de omni generi scibili. ' The Heidelberg edition (1486), and that of Strasburg (1504), both bear this title, but the first part was suppressed in the Friburg edition of the same year, as well as in the twelve subsequent editions which succeeded one another, at short intervals, till 1535. This work exercised a great ’ influence on the diffusion of mathematical and physical sciences, towards 40 COSMOS. of the fifteenth century, to Lord Bacon, and from Bacon to D’Alembert; and in recent times to an eminent physicist, Andre Marie Ampére.* The selection of an inappropriate Greek nomenclature has, perhaps, been even more prejudicial to the last of these attempts than the injudicious use of binary divisions, and the excessive multiplication of groups. The physical description of the world, considering the uni- verse as an object of the external senses, does undoubtedly require the aid of general physics and of descriptive natural history, but the contemplation of all created things, which are linked together, and form one whole, animated by internal forces, gives to the science we are considering a peculiar cha- racter. Physical science considers only the general properties of bodies; it is the product of abstraction,—a generalization of perceptible phenomena; and even in the work in which were laid the first foundations of general physics, in the eight books on physics of Aristotle,t all the phenomena of nature are considered as depending upon the primitive and vital action of one sole force, from which emanate all the movements of the universe. The terrestrial portion of phy- sical cosmography, for which I would willingly retain the | expressive designation of physical geography, treats of the dis- — tribution of magnetism in our planet with relation to its | intensity and direction, but does not enter into a considera- the beginning of the sixteenth century, and Chasles, the learned author of L’ Apergu Historique des Méthodes en Géométrie (1837), has shown the great importance of Reisch’s Encyclopedia in the history of mathematics in the middle ages. I have had recourse to a passage in the Margarita Philosophica, found only in the edition of 1513, to elucidate the important question of the relations between the statements of the geographer of Saint-Die, Hylacomilus (Martin Waldseemiiller), the first who gave the name of America to the New Continent, and those of Amerigo Vespucci, René, King of Jerusalem and Duke of Lorraine, as also those contained in the celebrated editions of Ptolemy, of 1513 and 1522. See my Examen Critique de la Géographie du Nouveau Continent, et des Progrés de l As- tronomie Nautique aux l5e et 16e Siécles, t. iv., pp. 99—125. * Ampére, Essai sur la Phil. des Sciences, 1834, p. 25. Whewell, Philosophy of the Inductive Sciences, vol. ii., p. 277. Park, Pantology, Bes 7 + All changes in the physical world may be reduced to motion. Aris- tot., Phys. Ausc., iii., 1 and 4, pp. 200, 201. Bekker, viii., 1, 8, and 9, pp- 250, 262, 265. De Genere et Corr.,ii., 10, p. 336. Pseudo- Aristot., De Mundo, cap. vi., p. 398. : : INTRODUCTION. 41 tion of the laws of attraction or repulsion of the poles, or the means of eliciting either permanent or transitory electro-mag- netic currents. Physical geography depicts in broad outlines the even or irregular configuration of continents, the relations of superficial area, and the distribution of continental masses in the two hemispheres, a distribution which exercises a power- ful influence on the diversity of climate and the meteorological modifications of the atmosphere ; this science defines the cha- racter of mountain-chains, which, having been elevated at dif- ferent epochs, constitute distinct systems, whether they run in arallel lines, or intersect one another; determines the mean eight of continents above the level of the sea, the position of the centre of gravity of their volume, and the relation of the highest summits of mountain-chains to the mean elevation of their crests, or to their proximity with the sea-shore. It depicts the eruptive rocks as principles of movement, acting upon the sedimentary rocks by traversing, uplifting, and inclin- ing them at various angles; it considers volcanoes either as isolated or ranged in single or in double series, and extend- ing their sphere of action to various distances, either by rais- ing long and narrow lines of rocks, or by means of circles of commotion, which expand or diminish in diameter in the course of ages. ‘This terrestrial portion of the science of the Cosmos describes the strife of the liquid element with the solid land ; it indicates the features possessed in common by all great rivers in the upper and lower portion of their course, and in their mode of bifurcation when their basins are unclosed ; and shows us rivers breaking through the highest mountain- chains, or following for a long time a course parallel to them, either at their base, or at a considerable distance, where the elevation of the strata of the mountain system and the direc- tion of their inclination correspond to the configuration of the table-land. It is only the general results of compara- tive orography and hydrography that belong to the science whose true limits I am desirous of determining, and not the special enumeration of the greatest elevations of our globe, of active volcanoes, of rivers, and the number of their tributaries; these details falling rather within the domain of geography properly so called. We would here only consider phenomena in their mutual connection, and in their relations to different zones of our planet, and to its physical constitution generally. 42 - ©OSMOS, ‘The specialities both of inorganic and organised. matter, classed according to analogy of form and composition, un- doubtedly constitute a most interesting branch of study, but they appertain to a sphere of ideas haying no affinity with the subject of this work. The description of different countries certainly oe us with the most important materials for the composition of’a physical geography; but the combination of these different ‘descriptions, ranged im series, would as little give us a true amage of the general conformation of the irregular surface of our globe, as a succession of all the floras of different regions would constitute that which I designate as a Geography of Plants. It is by subjecting isolated observations to the process of thought, and by combining and comparing them, A that we are enabled to discover the relations existing in common between the climatic distribution of beings and the individuality of organic forms (in the morphology or descrip- tive natural history of plants and animals); and it is by | induction that we are led to comprehend numerical laws, the’ proportion of natural families to the whole number of species, and to designate the latitude or geographical position of the. zones in whose plains each organic form attains the maximum © -of its development. Considerations of this nature, by their tendency to generalization, impress a nobler character on the physical description of the globe; and enable us to understand _how the aspect of the scenery, that is to say, the impression _ produced upon the mind by the physiognomy of the vegetation, _ depends upon the local distribution, the number, and the luxu- _viance of growth of the vegetable forms predominating i in the -general mass. The catalogues of organised beings, to which was formerly given the pompous title of Systems of Nature, present us with an admirably connected arrangement by ana- _logies of structure, either in the perfected development of these beings, or in the different phases which, in accordance with the views of a spiral evolution, affect in vegetables the leaves, bracts, calyx, corolla, and fructifying organs; and in animals, with more or less symmetrical regulari ity, the cellular / and fibrous tissues, and their perfect or but obscurely deve- | loped articulations. But these pretended systems of nature, || however ingenious their mode of classification may be, do not _ show us organic beings, as they are distributed im groups— INTRODUCTION. 43 ‘throughout our planet, according to their different relations of latitude and elevation above the level of the sea, and to climatic influences, which are owing to general and often very remote causes. The ultimate aim of physical geography is, however, as we have already said, to recognise unity in the vast diversity of phenomena, and by the exercise of thought and the combination of observations, to discern the constancy of phenomena in the midst of apparent changes. In the exposition of the terrestrial portion of the Cosmos, it will occasionally be necessary to descend to very special facts; but this will only be in order to recall the connection existing between the actual distribution of organic beings ‘over the globe, and the laws of the ideal classification by natural families, analogy of internal organization, and pro- gressive evolution. . It follows from these discussions on the limits of the ‘various sciences, and more particularly from the distinction which must necessarily be made between descriptive botany ‘(morphology of vegetables) and the geography of plants, that ‘m the physical history of the globe, the innumerable multitude of organised bodies which embellish creation are considered. rather according to zones of habitation or stations and to differently inflected isothermal bands, than with reference to the principles of gradation in the development of internal organism. Notwithstanding this, botany and zoology, which constitute the descriptive natural history of all organised ‘beings, are the fruitful sources whence we draw the materials ‘necessary to give a solid basis to the study of the mutual -telations and connection of phenomena. ~ ‘We will here subjoim one important observation, by way of elucidating the connection of which we have spoken. The ‘first general glance over the vegetation of a vast extent of a content shows us forms the most dissimilar—gramineew and ‘orehidez, coniferee and oaks, in local approximation to one another ; whilst natural families and genera, instead of being locally associated, are dispersed as if by chance. ‘This dis- persion is, however, only apparent. The physical description of the globe teaches us that vegetation everywhere presents , numerically constant relations in the development of its forms and types; that in the same climates, the species which are “wanting in one country are replaced in a neighbouring one by 44 COSMOS. other species of the same family; and that this law of sub- stitution, which seems to depend upon some inherent mys- teries of the organism, considered with reference to its origin, maintains in contiguous regions a numerical relation between the species of various great families and the general mass of the phanerogamic plants constituting the two floras. We thus find a principle of unity and a primitive plan of dis- tribution revealed in the multiplicity of the distinct organiza- tions by which these regions are occupied; and we also discover in each zone, and diversified according to the families of plants, a slow but continuous action on the aerial ocean, depending upon the influence of light—the primary condition of all organic vitality—on the solid and liquid surface of our planet. It might be said, in accordance with a beautiful expression of Lavoisier, that the ancient marvel of the myth of Prometheus was incessantly renewed before our eyes. If we extend the course which we have proposed, following in the exposition of the physical description of the earth to the sidereal part of the science of the Cosmos, the delineation of the regions of space and the bodies by which they are occupied, we shall find our task simplified in no common. degree. If, according to ancient but unphilosophical forms of nomenclature, we would distinguish between physics, that is to say, general considerations on the essence of matter, and the forces by which it is actuated, and chemistry, which treats of the nature of substances, their elementary com- position, and those attractions that are not determined solely by the relations of mass, we must admit that the description of the earth comprises at once physical and chemical actions. In addition to gravitation, which must be considered as a primitive force im nature, we observe that attractions of another kind are at work around us, both in the interior of our planet and on its surface. These forces, to which we apply the term chemical affinity, act upon molecules in contact, or at infinitely minute distances from one another,* * On the question already discussed by Newton, regarding the differ- ence existing between the attraction of masses and molecular attraction, see Laplace, Exposition du Systéme du Monde, p. 384, and supplement to book x. of the Mécanique Céleste, pp. 3,4; Kant, Metaph. Anfangs- griinde der Naturwissenschaft, Sim. Werke, 1839, bd.v., s. 309 (Meta- physical Principles of the Natural Sciences); Pectet, Physigue, 1838, vol. i., pp. 59—63. INTRODUCTION. 45 and which being differently modified by electricity, heat, condensation in porous bodies, or by the contact of an intermediate substance, animate equally the inorganic world and animal and vegetable tissues. If we except the small asteroids which appear to us under the forms of aérolites and shooting stars, the regions of space have hitherto pre- sented to our direct observation physical phenomena alone ; and in the case of these, we know only with certainty the effects depending upon the quantitative relations of matter or the distribution of masses. The phenomena of the regions of space may consequently be considered as influenced by simple dynamical laws—the laws of motion. The effects that may arise from the specific difference and the heterogeneous nature of matter, have not hitherto entered into our calculations of the mechanism of the heayens. The only means by which the inhabitants of our planet can enter into relation with the matter contained within the regions of space, whether existing in scattered forms or united into large spheroids, is by the phenomena of light, the propagation of luminous waves, and by the influence universally exercised by the force of gravitation or the attraction of masses. The existence of a periodical action of the sun and moon on the variations of terrestrial magnetism is even at the present day extremely problematical. We have no direct experimental knowledge regarding the properties and specific qualities of the masses circulating in space, or of the matter of which they are probably composed, if we except what may be derived from the fall of aérolites or meteoric stones, which, as we have already observed, enter within the limits of our ter- restrial sphere. It will be sufficient here to remark, that the direction and the excessive velocity of projection (a velocity wholly planetary) manifested by these masses, render it more than probable that they are small celestial bodies, which being attracted by our planet are made to deviate from their original course, and thus reach the earth enveloped in vapours, and in a high state of actual incandescence. The familiar aspect of these asteroids, and the analogies which they present with the minerals composing the earth’s crust, undoubtedly afford ample grounds for surprise ;* but, in my opinion, the only con- * [The analysis of an afrolite which fell a few years since in Maryland, United States, and was examined by Professor Silliman of Newhaven, 46° - COSMOS. clusion to be drawn from these facts is, that in general planets and other sidereal masses which, by the influence of a central body, have been agglomerated into rings of vapour, and sub- sequently into spheroids, being integrant parts of the same: system, and having one common origin, may likewise be: composed of substances chemically identical. Again, experi-: ments with the pendulum, particularly those prosecuted with. such rare precision by Bessel, confirm the Newtonian axiom,. that bodies the most heterogeneous in their nature (as water,. gold, quartz, granular limestone, and different masses of aérolites) experience a perfectly similar degree of accelera-. tion from the attraction of the earth. ‘To the experiments of. the pendulum may be added the proofs furnished by purely astronomical observations. The almost perfect identity of the: mass of Jupiter, deduced from the influence exercised by this. stupendous planet on its own satellites, on Encke’s comet. of: short period, and on the small planets Vesta, Juno, Ceres, and. Pallas, indicates with equal certainty, that within the limits of actual observation attraction is determined solely by: the’ quantity of matter.* - This absence of any perceptible difference in the nature of. matter, alike proved by direct observation and theoretical. deductions, imparts a high degree of simplicity to the me- chanism of the heavens. The immeasureable extent of the regions of space being subjected to laws of motion alone, the sidereal portion of the science of the Cosmos is based on the pure and abundant source of mathematical astronomy, as is the terrestrial portion on physics, chemistry, and organic morphology; but the domain of these three last-named sciences embraces the consideration of phenomena which are so complicated, and have, up to the present time, been found so little susceptible of the application of rigorous method, that the physical science of the earth cannot boast of the same Connecticut, gave the following results :—Oxide of iron 24; oxide of nickel, 1°25; silica, with earthy matter, 3°46; sulphur, atrace; = 28°71. Dr. Mantell’s Wonders of Geology. 1848. vol. i. p. 51.]|—Tr. ' * Poisson, Connaissances des Temps pour l’ Année 1836, pp. 64—66. Bessel, Poggendorff’s Annalen, bd. xxv., s. 417. Encke, Abhandlungen der Berliner Academie, (Trans. of the Berlin Academy,) 1826, s. 257. Mitscherlich, Lehrbuch der Chemie, (Manual of Chemistry,) 1837, bd. i., s. 352. ; INTRODUCTION, 47° certainty and simplicity in the exposition of facts and their mutual connection, which characterise the celestial portion ox the Cosmos. It is not improbable that the difference to which we allude may furnish an explanation of the cause which, in the earliest ages of intellectual culture amongst the Greeks, directed the natural philosophy of the Pythagoreans with more ardour to the heavenly bodies and the regions of space, than to the earth and its productions, and how through Philo- laiis, and subsequently through the analogous views of Aris- tarchus of Samos, and of Seleucus of Erythrea, this science has been made more conducive to the attainment of a know-. ledge of the true system of the world, than the natural philo- sophy of the Ionian school could ever be to the physical’ history of the earth. Giving but little attention to the pro- perties and specific differences of matter filling space, the great Italian school, in its Doric gravity, turned by pre- ference towards all that relates to measure, to the form of. bodies, and to the number and distances of the planets ;* whilst the Ionian physicists directed their attention to the qualities of matter, its true or supposed metamorphoses, and: to relations of origin. It was reserved for the powerful genius of Aristotle, alike profoundly speculative and practical, ° to sound with equal success the depths of abstraction and the inexhaustible resources of vital activity pervading the material world. Several highly distinguished treatises on physical geography are prefaced by an introduction, whose purely astronomical sections are directed to the consideration of the earth in its planetary dependence, and as constituting a part of that great system which is animated by one central body, the sun. This course is diametrically opposed to the one which I propose following. In order adequately to estimate the dignity of the Cosmos, it is requisite that the sidereal portion, termed by Kant the natural history of the heavens, should not be made subordinate to the terrestrial. In the science of the Cosmos, according to the expression of Aristarchus of Samos, the pioneer of the Copernican system, the sun with its satellites was nothing more than one of the innumerable stars by which Space 1s occupied. The physical history of the world must, * Compare Ottfried Miiller’s Doren, bd. i., s. 365. 48 COSMOS. therefore, begin with the description of the heavenly bodies, and with a geographical sketch of the universe, or I would rather say, a true map of the world, such as was traced by the bold hand of the elder Herschel. If, notwithstanding the smallness of our planet, the most considerable space and the most attentive consideration be here afforded to that which exclusively concerns it, this arises solely from the dispropor- tion in the extent of our knowledge of that which is accessible and of that which is closed to our observation. This subordina- tion of the celestial to the terrestrial portion is met with in the great work of Bernard Varenius,* which appeared in the middle of the seventeenth century. He was the first to dis- tinguish between general and special geography, the former of which he subdiyides into an absolute, or properly speaking, terrestrial part, and a relative or planetary portion, according * Geographia Generalis in qua affectiones generales telluris expli- cantur. The oldest Elzevir edition bears date 1650, the second 1672, and the third 1681; these were published at Cambridge, under New- ton’s supervision. This excellent work by Varenius is, in the true sense of the words, a physical description of the earth. Since the work Historia Natural de las Indias, 1590, in which the Jesuit Joseph de Acosta sketched in so masterly a manner the delineation of the New Continent, questions reJating to the physical history of the earth have never been considered with such admirable generality. Acosta is richer in original observations, while Varenius embraces a wider circle of ideas, since his sojourn in Holland, which was at that period the centre of vast commercial relations, had brought him in contact with a great number of well-informed travellers. Generalis sive Universalis Geographia dicitur que tellurem in genere considerat atque affectiones explicat, non habita particularium regionum ratione. The general description of the earth by “Varenius (Pars Absoluta, cap. i.—xxii.) may be considered as a treatise of comparative geography, if we adopt the term used by the author him- self (Geographia Comparativa, cap. xxxiiii—x..), although this must be understood in a limited acceptation. We may cite the following amongst the most remarkable passages of this book; the enumeration of the systems of mountains; the examination of the relations existing between their directions and the general form of continents (pp. 66, 76, Ed. Cantab., 1681); a list of extinct volcanoes, and such as were still in a state of activity; the discussion of facts relative to the general distribution of islands and archipelagoes (p. 220); the depth of the ocean relatively to the height of neighbouring coasts (p. 103); the uniformity of level observed in all open seas (p. 97); the dependence of currents on the prevailing winds; the unequal saltness of the sea; the configuration of shores (p. 139); the direction of the winds as the result of differences of temperature, &c. We may further instance the remarkable _considera- INTRODUCTION. 49 to the mode of considering our planet either with reference to} its surface in its different zones, or to its relations to the sun and moon. It redounds to the glory of Varenius, that his work on General and Comparative Geography should in so high a degree haye arrested the attention of Newton. The imperfect state of many of the auxiliary sciences from which this writer was obliged to draw his materials, prevented his work from corresponding to the greatness of the design, and it was reserved for the present age, and for my own country, to see the delineation of comparative geography, drawn in its full extent, and in all its relations with the history of man, by the skilful hand of Carl Ritter.* tions of Varenius regarding the equinoctial current from east to west, to which he attributes the origin of the Gulf Stream, beginning at Cape St. Augustin and issuing forth between Cuba and Florida (p. 140). Nothing can be more accurate than his description of the carrent which skirts the western coast of Africa, between Cape Verd and the island of Fernando Po in the Gulf of Guinea. Varenius explains the formation of spo- radic islands by supposing them to be ‘‘the raised bottom of the sea:’ magna spirituum inclusorum vi, sicut aliguando montes e terra protusos esse quidam scribunt, (p. 225). The edition published by Newton in 1681 (auctior et emendatior) unfortunately contains no additicns from this great authority; and there is not even mention made of the polar compression of the globe, although the experiments on the pendulum by Richer had been made nine years prior to the appearance of the Cam- bridge edition. Newton’s Principia Mathematica Philosophie Naturalis were not communicated in manuscript to the Royal Society until April 1686. Much uncertainty seems to prevail regarding the birthplace of Varenius. Jzcher says it was England, while, according to La Biogra- phie Universelle (b. xtvii., p. 495), he is stated to have been born at Amsterdam; but it would appear from the dedicatory address to the Burgomaster of that city, (see his Geographia Comparativa), that both suppositions are false. Varenius expressly says that he had sought refuge in Amsterdam, ‘‘because his native city had been burnt and completely destroyed during a long war,’’ words which appear to apply to the north of Germany, and to the devastations of the thirty years’ war. In his dedication of another work, Descriptio regni Japonie, (Amst. 1649), to the senate of Hamburgh, Varenius says that he prose- cuted his elementary mathematical studies in the gymnasium of that city. There is, therefore, every reason to believe that this admirable geographer was a native of Germany, and was probably born at Luneburg, (Witten. Mem. Theol., 1685, p. 2142; Zedler, Universal-Lewxicon, vol. xtvi., 1745, p. 187.) * Carl Ritter’s Erdkunde im Verhiiltniss zur Natur und zur Gea schichte des Menschen, oder allyemeine vergleichende Geographie (Geo- E * 50 COSMOS. ‘ The enumeration of the most important results of the astro- nomical and: physical sciences which in the history of the Cosmos radiate towards one common focus, may perhaps, to a certain degree, justify the designation I have given to my work, and, considered within the circumscribed limits I have proposed to myself, the undertaking may be esteemed less adventurous than the title. The introduction of new terms, especially with reference to the general results of a science which ought to be accessible to all, has always been greatly in opposition to my own practice; and whenever I have enlarged upon the established nomenclature, it has only been in the specialities of descriptive botany and zoology, where the introduction of hitherto unknown objects rendered new names necessary. The denominations of physical descriptions of the universe, or physical cosmography, which I use mmdis- criminately, have been modelled upon those of physical deserip- tions of the earth, that is to say, physical geography, terms that have long been in common use. Descartes, whose genius was one of the most powerful manifested in any age, has left us a few fragments of a great work, which he intended publishing under the title of Monde, and for which he had prepared him- » self by special studies, including even that of human anatomy. * The uncommon, but definite expression of the science of the Cosmos recalls to the mind of the inhabitant of the earth that we are treating of a more widely-extended horizon; of the assemblage of all things with which space is filled, from the remotest nebulz to the climatic distribution of those delicate tissues of vegetable matter, which spread a variegated coyer- ing over the surface of our rocksy The influence of narrow-minded views peculiar to the earlier ages of civilisation led in all languages to a confu ion of ideas in the synonymic use of the words earth and world; whilst the common expressions, voyages round the world, map of the world, and new world, afford further illustrations of the -game confusion. The more noble and precisely-defined ex- ‘pressions of system of the world, the planetary world, and crea- tion and age of the world, relate either to the totality of the ‘substances by which space is filled, or to the origin of the whole universe. ‘graphy in relation to Nature and the History of Man, or general Come parative Geography). INTRODUCTION. 51 ‘. It was natural that, in the midst of the extreme variability of phenomena presented by the surface of our globe, and the aérial ocean by which it is surrounded, man should have been impressed by the aspect of the vault of heaven, and the uni- form and regular movements of the sun and planets. Thus the word Cosmos, which primitively, in the Homeric ages, indicated an idea of order and harmony, was subsequently adopted in scientific language, where it was gradually applied ‘to the order observed in the movements of the heayenly ‘bodies, to the whole universe, and then finally to the world in which this harmony was reflected to. us. According to the assertion of Philolaiis, whose fragmentary works have been so ably commented upon by Béckh, and conformably to the general testimony of antiquity, Pythagoras was the first who used the word Cosmos to designate the order that reigns in ‘the universe, or entire world.* From the Italian school of philosophy, the expression passed in this signification into the language of those early poets of * Kécpoc, in the most ancient, and at the same time most precise, definition of the word, signified ornament (as an adornment for a man, a woman, or a horse); taken figuratively for edragia, it implied the order or adornment of a discourse. According to the testimony of all the ancients, it was Pythagoras who first used the word to designate the order in the universe, and the universe itself. Pythagoras left no writings; but ancient attestation to the truth of this assertion is to be found in several passages of the fragmentary works of Philolaiis (Stob., Eclog., pp- 360 and 460, Heeren) ; pp. 62, 90, in Béckh’s German edition. I do not, according to the example of Nake, cite Timzus of Locris, since his authenticity is doubtful. Plutarch (De Plac. Phil., ii, 1), says in the most express manner, that Pythagoras gave the name of Cosmos to the universe on account of the order which reigned throughout it; so likewise does Galen (Hist. Phil., p. 429). This word, together with its novel signification, passed from the schools of philosophy into the language of ‘poets and prose writers. Plato designates the heavenly bodies by the name of Uranos, but the order pervading the regions of space he too terms the Cosmos, and in his Timeus, (p. 30 B.) he says that the world is an animal endowed with a soul (xécpou Céov tubixov). Compare Anaxag. Claz., ed. Schaubach, p. 111, and Plut., De Plac. Phil., ii, 3) on spirit apart from matter, as the ordaining power of nature. In Aristotle (De Celo, 1, 9,) Cosmos signifies ‘‘the universe and the order pervading it,’’ but it is likewise considered as divided in space into two parts,—the sublunary world, and the world above the moon. (Meteor. 1, 2, 1, and I, 3,13, pp. 339 a, and 340 5, Bekk.) The definition of Cosmos, which I have already cited, is taken from Pseudo-Aristoteles de Mundo, cap. ii. ‘(p. 391); the passage referred to is as follows: Kéopog éori ctornpa é . E2 52 COSMOS. nature, Parmenides and Empedocles, and from thence into the works of prose writers. We will not here enter into a discussion of the manner in which, according to the Pytha- gorean views, Philolaiis distinguishes between Olympus, ovpaved Kai yij¢ Kai Ty éy TobToIg TEpLEXopévwy dicewv. Aéyerat dé Kai éripwe KooXoc 1) THY Ohwy Taéte TE Kal draKdopNotc, Ud OsHy TE Kai bud Oey purdarropévn. Most of the passages occurring in Greek writers ‘on the word Cosmos, may be found collected together in the controversy ‘between Richard Bentley and Charles Boyle (Opuscula Philologica, 1781, ~ pp. 347, 445; Dissertation upon the Epistles of Phalaris, 1817, p. 254); on the historical existence of Zaleutus, legislator of Leucris, in Niake’s excellent work, Sched. crit., 1812, pp. 9, 15; and finally, in Theophilus Schmidt, Ad Cleom. cycl. theor., met. I, 1 p.ix., 1 and 99. Taken ina more limited sense, the word Cosmos is also used in the plural (Plut., 1, 5,) either to designate the stars (Stob., 1, p. 514; Plut., 11, 13,) of the. innumerable systems scattered like islands through the immensi:y of space, and each composed of a sun andamoon. (Anax. Claz., Fraum. pp- 89,93, 120; Brandis, Gesch. der Griechisch-Romischen Philosophie, b. i., s. 252 (History of the Greco-Roman Philosophy). Each of these groups forming thus a Cosmos, the universe, TO way, the word must be understood in a wider sense (Plut. ii, 1.) It was not until long after the time of the Ptolemies that the word was applied to the earth. Béckh has made known inscriptions in praise of Trajan and Adrian (Corpus Inser. Gree., 1, n. 334 and 1306) in which Kéopog occurs for oickovpevy, in the same manner as we still use the term world to signify the earth alone. We have already mentioned the singular . division of the regions of space into three parts, the Olympus, Cosmos, and QOuranos, (Stob. 1, p. 488; Philolatis, pp. 94, 202); this division applies to the different regions surrounding that mysterious focus of the universe, the ‘Eoria row zavréc of the Pythagoreans. In the fragmentary passage in which this division is found, the term Ouwranos designates the innermost region, situated between the moon and earth; this is the domain of changing things. The middle region where the planets circulate in an invariable and harmonious order, is, in accordance with the special con- ceptions entertained of the universe, exclusively termed Cosmos, whilst the word Olympus is used to express the exterior or igneous region. Bopp, the profound philologist, has remarked, ‘‘ that we may deduce, as Pott has done, Etymol. Forschungen, th.i., s.39 and 252 (Etymol. Researches) the word Késpoc from the Sanscrit root ’sud’, purificari, by assuming two conditions ; first, that the Greek « in kécpoc comes from the palatial c, which Bopp represents by ’s and Pott by ¢, (in the same manner as déka, decem, tathun in Gothic, comes from the Indian word désan) and next, that the Indian d’ corresponds as a general rule with the Greek 0 ( Veryleichende Grammatik, § 99,—Comparative Grammar), which shows the relation of cécpoc (for c6040¢) with the Sanscrit root ’sud’, whence is also derived kaQcpéc. Another Indian term for the world is gagat (pronounced dschagat), which is, properly speaking, the present participle of the verb INTRODUCTION. 53 , Uranus, or the heavens, and Cosmos, or how the same word, used in a plural sense, could be applied to certain heavenly bo- dies (the planets) revolving round one central focus of the world, or to groups of stars. In this work f{ use the word Cosmos in conformity with the Hellenic usage of the term subsequently to the time of Pythagoras, and in accordance with the precise definition given of it in the treatise entitled De Mundo, which was long erroneously attributed to Aristotle. It is the assem- blage of all things in heaven and earth, the universality of ereated things constituting the perceptible world. If scien- tific terms had not long been diverted from their true verbal signification, the present work ought rather to have borne the title of Cosmography, divided into Uranography and G'eo- - graphy. e Romans, in their feeble essays on philosophy, . imitated the Greeks by applying to the universe the term gagami (1 go), the root of whichis gd. In restricting ourselves to the cirele of Hellenic etymologies, we find (Eiymol> M., pp. 532, 12) that Koopog is intimately associated with caZw, or rather with caivupat, whence we have xexacpévoc or kekadpévoc. Welcker, (Eine Kretische Col. in Theben, s. 23, A Cretan colony in Thebes,) combines with this the name Kadpoc, as in Hesychius cdduog signifies a Cretan suit of arms. When the scientific language of Greece was introduced amongst the Romans, the word mundus, which at first had only the primary meaning of kéopog (female ornament), was applied to designate the entire universe. Ennius seems to have been the first who ventured upon this innovation. In one of the fragments of this poet, preserved by Macrobius, on the occasion of his quarrel with Virgil, we find the word used in its novel mode of acceptation. “* Mundus Celi vastus constitit silentio’’ (Sat. vi., 2). Cicero also says: ** quem nos lucentem mundum vocamus.”’ (Timeeus, S. de Univer., cap. x.) The Sanscrit root mand, from which Pott derives the Latin mundus, (Etym. Forsch, th. i., s. 240,) combines the double signification of shining and adorning. Léka designates in Sanscrit the world and people in general, in the same manner as the French word monde, and is derived, according to Bopp, from /é% (to see and shine) ; it is the same with the Sclayonic root sujet, which means both light and world. (Grimm, Deutsche Gramm., b. iii., s. 394, German Grammar.) The word welt, which the Germans make use of at the present day, and which was weralt in old “German, worold in old Saxon, and véru/d in Anglo-Saxon, was, according to James Grimm’s interpretation, a period of time, an age (seculum), rather than a term used for the world in space. The Etruscans figured to themselves mundus as an inverted dome, symmetrically opposed to the celestial. vault (Ottfried Miiller’s Etrusken, th. ii., s. 96, &c.) Taken in a still more limited sense, the word appears to have signified amongst the Goths the terrestrial surface girded by seas (marei, meri), the merigard, literally garden of seas, 54 cOosMOS, mundus, which, in its primary meaning, indicated nothing more than ornament, and did not even imply order or regu- larity in the disposition of parts. It is probable that the introduction into the language of Latium of this technical term as an equivalent for Cosmos, in its double signification, is due to Ennius,* who was a follower of the Italian school, and the translator of the writings of Epicharmus and some of his. pupils, on the Pythagorean philosophy. We would first distinguish between the physical history and the physical description of the world. The former, con- ~ ceived in the most general sense of the word, ought, if mate-_. rials for writing it existed, to trace the variations experienced by the universe in the course of ages, from the new stars. which have suddenly appeared and disappeared in ‘the vault of heaven, from nebulze dissolving or condensing,—to the first. stratum of cryptogamic vegetation on the still imperfectly cooled surface of the earth, or on a reef of coral uplifted ‘ from the depths of ocean. The physical description of the. world presents a picture of all that exists in space—of the simultaneous action of natural forces together with the phe- nomena which they produce. But if we would correctly comprehend nature, we must not entirely or absolutely separate the consideration of the. present state of things from that of the successive phases through which they have passed. We cannot form a just: conception of their nature without looking back on the mode: of their formation. It is not organic matter alone that is continually undergoing change and being dissolved to form new combinations. The globe itself reveals at every phase -. Of its existence the mystery of its former conditions. We cannot survey the crust of our planet without recog-. - nising the traces of the prior existence and destruction of an organic world. The sedimentary rocks present a succes- sion of organic forms, associated in groups, which have suc- Cessively displaced and succeeded each other. The different * See, on Ennius, the ingenious researches of Leopold Krahner, in his. Grundlinien zur Geschichte des Verfalis der Romischen Staats-Religion, 1837, s. 41—45 (Outlines of the History of the Decay of the Esta-. blished Religion amongst the Romans). In all probability Ennius did not quote from writings of Epicharmus himself, but from poems se “a7 in the name of that philosopher, and in accordance with his views. INTRODUCTION. 56: superimposed strata thus display to us the faunas and floras of different epochs. In this sense the description of nature is intimately connected with its history; and the geologist, who is guided by the connection existing amongst the facts observed, cannot form a conception of the present without pursuing, through countless ages, the history of the past. In tracing the physical delineation of the globe, we behold the present and the past reciprocally incorporated, as it were, _ with one another; for the domain of nature is like that of lan- '“guages, in which etymological research reveals a successive development, by showing us the primary condition of an idiom reflected in the forms of speech in use at the present day. The study of the material world renders this reflection of the past peculiarly manifest, by displaying in the process of for- mation rocks of eruption and sedimentary strata, similar to those of former ages. If I may be allowed to borrow a strik- ing illustration from the geological relations by which the physiognomy of a country is determined, I would say that domes of trachyte, cones of basalt, lava-streams (coulées) of - amygdaloid with elongated and parallel pores, and white deposits of pumice, intermixed with black scorie, animate the scenery by the associations of the past which they awaken— acting upon the imagination of the enlightened observer like traditional records of an earlier world. Their form is their history. The sense in which the Greeks and Romans originally em- _ ployed the word /istory, proves that they too were intimately eonvinced that tc form a complete idea of the present state of the universe, it was necessary to consider it in its successive phases. It is not, however, in the definition given by Valerius Flaccus,* but in the zoological writings of Aristotle, that the word /isiory presents itself as an exposition of the results of experience and observation. The physical description of the world by Pliny the elder, bears the title of Natural History, . while in the letters of his nephew it is designated by the nobler term of History of Nature. The earlier Greek his- torians did not separate the descriptions of countries from the narrative of events of which they had been the theatre. With these writers, physical geography and history were long intimately associated, and remained simply but elegantly blended until the period of the development of political inte-. * Aul. Gell., Noct. Att., v. 18. . 56 COSMOS. rests, when the agitation in which the lives of men were passed caused the geographical portion to be banished from the history of nations, and raised into an independent science. It remains to be considered whether, by the operation of thought, we may hope to reduce the immense diversity of phenomena comprised by the Cosmos to the unity of a prin- ciple, and the evidence afforded by rational truths. In the present state of empirical knowledge, we can scarcely flatter ourselves with such a hope. Experimental sciences, based on the observation of the external world, cannot aspire to completeness; the nature of things, and the imperfection of our organs, are alike opposed to it. We shall never succeed in exhausting the immeasurable riches of nature; and no generation of men will ever have cause to boast of having comprehended the total aggregation of phenomena. It is only _ by distributing them into groups, that we have been able, in the -case of a few, to discover the empire of certain natural laws, ‘ grand and simple as nature itself. The extent of this empire will no doubt increase in proportion as physical sciences are more perfectly developed. Striking proofs of this adyance-_ ment have been made manifest in our own day, in the pheno- mena of electro-magnetism, the propagation of luminous - wayes and radiating heat. In the same manner, the fruitful doctrine of evolution shows us how, in organic development, all that is formed is sketched out beforehand, and how the tissues of vegetable and animal matter uniformly arise from the multiplication and transformation of cells. The generalization of laws, which being at first bounded by narrow limits, had been applied solely to isolated groups of phenomena, acquires in time more marked gradations, and gains in extent and certainty, as long as the process of reason- ing is applied strictly to analogous phenomena; but as soon as dynamical views prove insufficient where the specific pro- perties and heterogeneous nature of matter come into play, it is to be feared that by persisting in the pursuit of laws we may find our course suddenly arrested by an impassable chasm. The principle of unity is lost sight of, and the guiding clue) is rent asunder whenever any specific and peculiar kind of action manifests itself amid the active forces of nature. The law of equivalents and the numerical proportions of composi- INTRODUCTION. 57 - tion, so happily recognised by modern chemists, and pro- claimed under the ancient form of atomic symbols, still remains isolated and independent of mathematical laws of motion and gravitation. Those productions of nature which are objects of direct observation may be logically distributed. in classes, orders, and - families. This form of distribution undoubtedly sheds some). light on descriptive natural history, but the study of organ- ised bodies, considered in their linear connection, although it may impart a greater degree of unity and simplicity to the distribution of groups, cannot rise to the height of a classifi- cation based on one sole principle of composition and internal organisation. As different gradations are presented by the laws of nature according to the extent of the horizon, or the limits of the phenomena to be considered, so there are like- | wise differently graduated phases in the investigation of the - external world. Empiricism originates in isolated views, which are subsequently grouped according to their analogy or dissimilarity. To direct observation succeeds, although long afterwards, the wish to prosecute experiments,—that is to say, to evoke phenomena under different determined condi- tions. The rational experimentalist does not proceed at hazard, but acts under the guidance of hypotheses, founded on a half indistinct and more or less just intuition of the con- nection existing among natural objects or forces. That which has been conquered by observation or by means of experi- ments, leads, by analysis and induction, to the discovery of , empirical laws. These are the phases in human intellect that have marked the different epochs in the life of nations; and by means of which that great mass of facts has been accumulated which constitutes at the present day the solid basis of the natural sciences. Two forms of abstraction conjointly regulate our knowledge, namely, relations of guantity, comprising ideas of number and size, and relations of guality, embracing the consideration of the specific properties and the heterogeneous nature of matter. The former, as being more accessible to the exercise of thought, appertains to mathematics, the latter, from its apparent mys- teries and greater difficulties, falls under the domain of the chemical sciences. In order to submit phenomena to caleu- lation, recourse is had to a hypothetical construction of matter, 58 COSMOS. by a combination of molecules and atoms, whose number, form, position, and polarity determine, modify, or vary phe- nomena. _. The mythical ideas long entertained of the imponderable: substances and vital forces peculiar to each mode of organiza- tion, have complicated our views generally, and shed an. uncertain light on the path we ought to pursue. The most various forms of intuition have thus, age after age, ‘aided in augmenting the prodigious mass of empirical know- ledge, which in our own day has been enlarged with ever increasing rapidity. The investigating spirit of man strives. from time to time, with varying success, to break through, those ancient forms and symbols invented, to subject rebellious matter to rules of mechanical construction, We are still very far from the time when it will be possible for us to reduce, by the operation of thought, all that we: perceive by the senses, to the unity of a rational principle. It may even be doubted if such a victory could ever be achieved in the field of natural philosophy. The complieca- tion of phenomena, and the vast extent of the Cosmos, would seem to oppose such a result; but even a partial solution of. | the problem,—the tendency towards a comprehension of the: phenomena of the universe,—will not the less remain the eternal and sublime aim of every investigation of nature. _ In conformity with the character of my former writings, as well as with the labours in which I have been engaged during” my scientific career, in measurements, experiments, and the investigation of facts, I limit myself to the domain of empi- rical ideas. dente The exposition of mutually connected facts does not exclude: the classification of phenomena according to their rational. connection, the generalization of many specialities in the. great mass of observations, or the attempt to discover laws. Conceptions of the universe solely based upon reason and the principles of speculative philosophy, would no doubt assign a still more exalted aim to the science of the Cosmos. I am far from blaming the efforts of others solely because their success’ has hitherto remained very doubtful. Contrary to the wishes. and counsels of those profound and powerful thinkers, who haye given new life to speculations which were already fami- liar to the ancients, systems of natural philosophy have in our. INTRODUCTION. 59 own country for some time past turned aside the minds of men from the graver study of mathematical and physical sciences. The abuse of better powers which has led many of our noble but ill-judging youth into the saturnalia of a. purely ideal science of nature has been signalised by the in- toxication of pretended conquests, by a novel and fantastically symbolical phraseology, and by a predilection for the formule of a scholastic rationalism, more contracted in its views than any known to the middle ages. I use the expression “abuse — of better powers,” because superior intellects devoted to phi- losophical pursuits and experimental sciences have remained strangers to these saturnalia. The results yielded by an earnest investigation in the path of experiment, cannot be at variance with a true philosophy of nature. If there be any contradiction, the fault must lie either in the unsoundness of speculation, or in the exaggerated pretensions of empiri- cism, which thinks that more is proved by experiment than is actually derivable from it. External nature may be opposed to the intellectual world, as if the latter were not comprised within the limits of the former; or nature may be opposed to art when the latter is defined as a manifestation of the intellectual power of man; _ but these contrasts, which we find reflected in the most cul- tivated languages, must not lead us to separate the sphere of nature from that of mind, since such a separation would reduce the physical science of the world to a mere aggrega- tion of empirical specialities. Science does not present itself to man, until mind conquers matter, in striving to subject the result of experimental investigation to rational combinations. Science is the labour of mind applied to nature, but the exter- nal world has no real existence for us beyond the image reflected within ourselves through the medium of the senses.” As intelligence and forms of speech, thought and its verbal symbols, are united by secret and indissoluble links, so does the external world blend almost unconsciously to ourselves with our ideas and feelings. “ External phenomena,” says Hegel in his Philosophy of History, “are in some degree translated in our inner representations.” The objective world, conceived and reflected within us by thought, is subjected to the eternal and necessary conditions of our intellectual being. The activity of the mind exercises itself on the elements fure 60 COSMOS. nished to it by the perceptions of the senses. Thus in the early ages of mankind there manifests itself in the simple intuition of natural facts, and in the efforts made to compre-. hend them, the germ of the philosophy of nature. These ideal tendencies vary, and are more or less powerful, accord- ing to the individual characteristics and moral dispositions of nations, and to the degrees of their mental culture, whether attained amid scenes of nature that excite or chill the imagi- nation. History has preserved the record of the numerous attempts that have been made to form a rational conception of the whole world of phenomena, and to recognise in the universe the action of one sole active force by which matter is pene- trated, transformed and animated. These attempts are traced in classical antiquity in those treatises on the principles of things which emanated from the Ionian school, and in which all the phenomena of nature were subjected to hazard- ous speculations, based upon a small number of observations. By degrees, as the influence of great historical events has favoured the development of every branch of science sup- ported by observation, that ardour has cooled, which formerly led men to seek the essential nature and connection of things by ideal construction andin purely rational principles. In recent times, the mathematical portion of natural philosophy has been most remarkably and admirably enlarged. The method and the instrument (analysis) have been simulta- neously perfected. That which has been acquired by means so different—by the ingenious application of atomic supposi- tions, by the more general and intimate study of phenomena, and by the improved construction of new apparatus—is the common property of mankind, and should not in our opinion now, more than in ancient times, be withdrawn from the free exercise of speculative thought. It cannot be denied, that in this process of thought the results of experience have had to contend with many disad- vantages; we must not therefore be surprised if in the per- petual vicissitude of theoretical views, as is ingeniously expressed by the author of Gardano Lruno,* “ most men see nothing in philosophy but a succession of passing meteors, * Schelling’s Bruno, iiber das gitiliche und natiiraliche Princip. der Dinge, § 181 (Bruno, on the Divine and Natural Principlaof Things). ; INTRODUCTION. 61 whilst eyen the grander forms in which she has revealed herself share the fate of comets, bodies that do not rank in popular opinion amongst the eternal and permanent, works of nature, but are regarded as mere fugitive apparitions of igneous vapour.”” We would here remark that the abuse of thought and the false track it too often pursues, ought not to sanction an opinion derogatory to intellect, which would imply that the domain of mind is essentially a world of vague fan- tastic illusions, and that the treasures accumulated by laborious observations in philosophy are powers hostile to its own empire. It does not become the spirit which characterises the present age, distrustfully to reject every generalization of views, and every attempt to examine into the nature of things by the process of reason and induction. It would be a denial of the dignity of human nature and the relative importance of the faculties with which we are endowed, were we to condemn at one time austere reason engaged in investigating causes and their mutual connections, and at another that exercise of the imagination whch prompts and excites discoveries by its - creative powers. bo END OF INTRODUCTION. 62 Cuapter I. DELINEATION OF NATURE. GENERAL REVIEW OF NATURAL PHENOMENA. Wuen the human mind first attempts to subject to its control the world of physical phenomena, and strives by meditative contemplation to penetrate the rich luxuriance of living nature, and the mingled web of free and restricted natural forces, man feels himself raised to a height from whence, as he embraces the vast horizon, individual things blend together in varied groups, and appear as if shrouded in a vapoury veil. These figurative expressions are used in order to illustrate the point of view from whence we would ‘consider the universe both in its celestial and terrestrial sphere. J am not insensible of the boldness of such an un- dertaking. Among all the forms of exposition to which these ~ pages are devoted, there is none more difficult than the general delineation of nature, which we purpose sketching, since we must not allow ourselves to be overpowered by a sense of the stupendous richness and variety of the forms presented to us, but must dwell only on the consideration of masses, either possessing actual magnitude or borrowing its semblance from the associations awakened within the subjective sphere of ideas. It is by a separation and classification of phenomena, by an intuitive insight into the play of obscure forces, and by animated expressions, in which the perceptible spectacle is reflected with vivid truthfulness, that we may hope to com- prehend and describe the univer sal. all (rd way) in a manner worthy of the dignity of the word Cosmos in its signification of universe, order of the world and adornment of this universal order. May the immeasurable diversity of phenomena which crowd into the picture of nature in no way detract from that harmonious impression of rest and unity, which is the ultimate object of every literary or purely artistical composition. Beginning with the depths of space and the regions of remotest nebule, we will gradually descend through the starry a DELINEATION OF NATURE, 63 “gone to which our solar system belongs, to our own terrestrial spheroid, circled by air and ocean, there to direct our atten- tion to its form, temperature, and magnetic tension, and to consider the fulness of organic life unfolding itself upon its surface beneath the vivifying influence of light. In this manner a picture of the world may, with a few strokes, be made to include the realms of infinity no less than the minute “microscopic animal and vegetable organisms, which exist in standing waters, and on the weather-beaten surface of our -rocks. All that can be perceived by the senses, and all that has been accumulated up to the present day by an attentive and variously directed study of nature, constitute the materials from which this representation is to be drawn, whose character is an evidence of its fidelity and truth. But the descriptive ‘picture of nature which we purpose drawing, must not enter too fully into detail, smce a minute enumeration of all vital forms, natural objects and processes is not requisite to the completeness of the undertaking. The delineator of nature must resist the tendency towards endless division, in order to avoid the dangers presented by the very abundance of our empirical knowledge. A considerable portion of the quali- tative properties of matter—or, to speak more in accordance with the language of natural philosophy, of the qualitative expression of forces—is doubtlessly still unknown to us; and ‘the attempt perfectly to represent unity in diversity must therefore necessarily prove unsuccessful. Thus besides the pleasure derived from acquired knowledge, there lurks in the mind of man, and tinged with a shade of sadness, an unsatis- fied longing for something beyond the present—a striving towards regions yet unknown and unopened. Such a sense of longing binds still faster the links which in accordance ‘with the supreme laws of our being connect the material with ‘the ideal world, and animates the mysterious relation existing between that which the mind receives from without, and that which it reflects from its own depths to the external world. If then nature (understanding by the term all natural objects and phenomena) be illimitable in extent and contents, it like- wise presents itself to the human intellect as a problem which cannot be grasped, and whose solution is impossible, since it requires a knowledge of the combined action of all natural forces. Such an acknowledgment is due where the actual 64 COSMOS. state and prospective development of phenomena constitute the sole objects of direct investigation, which does not venture to depart from the strict rules of induction. But although the incessant effort to embrace nature in its universality may remain unsatisfied, the history of the contemplation of the universe (which will be considered in another part of this work) will teach us how, in the course of ages, mankind has gradually attained to a partial insight into the relative depen- dence of phenomena. My duty is to depict the results of our knowledge in all their bearings with reference to the present. In all that is subject to motion and change in space, the |; ultimate aim, the very expression of physical laws depend upon mean numerical values; which show us the constant amid change, and the stable amid apparent fluctuations of phenomena. Thus the progress of modern physical science is especially characterised by the attainment and the rectifi- cation of the mean values of certain quantities by means of the processes of weighing and'measuring. And it may be said, that the only remaining and widely diffused hieroglyphic characters still in our writing—numbers—appear to us again, as powers of the Cosmos, although in a wider sense than that applied to them by the Italian School. The earnest investigator delights in the simplicity of nu- merical relations, indicating the dimensions of the celestial regions, the rnagnitudes and periodical disturbances of the heavenly bodies, the triple elements of terrestrial magnetism, the mean pressure of the atmosphere, and the quantity of heat which the sun imparts in each year, and in every season of the year, to all points of the solid and liquid surface of our planet. These sources of enjoyment do not, however, satisfy the poet of nature, or the mind of the inquiring many. To noth of these the present state of science appears as a blank, now that she answers doubtingly, or wholly rejects as un- answerable, questions, to which former ages deemed they could furnish satisfactory replies. In her severer aspect, and clothed with Jess luxuriance, she shows herself deprived of that seductive charm with which a dogmatising and symbo- lising physical philosophy knew how to deceive the under- standing and give the rein to imagination. Long before the discovery of the new world, it was believed that new lands in the far West might be seen from the shores of the Canaries DELINEATION OF NATURE. 65 and the Azores. These illusive images were owing not to any extraordinary refraction of the rays of light, but produced by an eager longing for the distant and the unattained. ‘The philosophy of the Greeks, the physical views of the middle ages, and even those of a more recent period have been eminently imbued with the charm springing from similar illusive phantoms of the imagination. At the limits of circum- scribed knowledge, as from some lofty island shore, the eye delights to penetrate to-distant regions. ‘The belief in the uncommon and the wonderful lends a definite outline to every manifestation of ideal creation; and the realm of fancy—a fairy-land of cosmological, geognostical and magnetic visions— becomes thus involuntarily blended with the domain of reality. Nature, in the manifold signification of the word—whether considered as the universality of all that is, and ever will be— as the inner moving force of all phenomena, or as their mys- terious prototype—reveals itself to the simple mind and feelings of man as something earthly, and closely allied to himself. It is only within the animated circles of organic structure that we feel ourselves peculiarly at home. ‘Thus wherever the earth unfolds her fruits and flowers, and gives food to countless tribes of animals, there the image of nature impresses itself most vividly upon our senses. The impression thus produced upon our minds limits itself almost exclusively to the reflection of the earthly. The starry vault and the wide expanse of the heavens, belong to a picture of the uni- verse, in which the magnitude of masses, the number of congregated suns and faintly glimmering nebule, although they excite our wonder and astonishment, manifest themselves to us in apparent isolation, and as utterly devoid of all evi- dence of their being the scenes of organic life. Thus even in the earliest physical views of mankind, heaven and earth have been separated and opposed to one another as an upper and lower portion of space. If then a picture of nature were to cor- respond to the requirements of contemplation by the senses, it ought to begin with a delineation of our native Earth. It should depict first the terrestrial planet as to its size and form; its increasing density and heat at increasing depths in its super- imposed solid and liquid strata; the separation of sea and land, and the yital forms animating both, developed in the F 66 COSMOS. cellular tissues of plants and animals; the atmospheric ocean with its waves and currents, through which pierce the forest- crowned summits of our mountain chains. After this delinea- tion of urely telluric relations, the eye would rise to the celestial regions, and the Earth would then, as the well-known seat of organic development, be considered as a planet, occu- pying place in the series of those heavenly bodies which circle round one of the innumerable host of self-luminous stars. This succession of ideas indicates the course pursued in the earliest stages of perceptive contemplation, and reminds us of the ancient conception of the “ sea-girt disc of earth,” supporting the vault of heayen. It begins to exercise its action at the spot where it originated, and passes from the consideration of the known to the unknown, of the near to the distant.- It corresponds with the method pursued in our elementary works on astronomy, (and which is so admirable in a mathematical point of view,) of proceeding from the apparent to the real movements of the heavenly bodies. Another course of ideas must, however, be pursued in a work, which proposes merely to give an exposition of what is known—of what may in the present state of our knowledge be regarded as certain, or as merely probable in a greater or lesser degree—and does not enter into a consideration of the proofs on which such results have been based. Here therefore we do not proceed from the subjective point of view of human interests. The terrestrial must be treated only as a part, subject to the whole. The view of nature ought to be grand and free, uninfluenced by motives of proximity, social sym- pathy, or relative utility. A physical cosmography—a picture of ‘he universe—does not begin, therefore, with the terrestrial, but with that which fills the regions of space. But as the sphere of contemplation contracts in dimension our percep- tion of the richness of individual parts, the fulness of phy- sical phenomena, and of the heterogeneous properties of matter becomes enlarged. From the regions in which we recognise only the dominion of the laws of attraction, we descend to our own planet, and to the intricate play of terres- trial forces. ‘The method here described for the delineation of nature, is opposed to that which must be pursued in esta- blishing conclusive results. The one enumerates what the other demonstrates. CELESTIAL PHENOMENA. 67 Man learns to know the external world through the organs of the senses. Phenomena of light proclaim the existence of matter in remotest space, and the eye is thus made the medium through which we may contemplate the universe. The dis- covery Of telescopic vision more than two centuries ago, has transmitted to latest generations a power, whose limits are as yet unattained. The first and most general consideration in the Cosmos is that of the contents of space,—the distribution of matter, or of crea- tion, as we are wont to designate the assemblage of all that is and ever will be developed. We see matter either agglomerated into rotating, revolving spheres of different density and size, or scattered through space in the form of self-luminous vapour. If we consider first the cosmical vapour dispersed in definite nebulous spots, its state of aggregation will appear constantly to vary. Sometimes appearing separated into round or ellip- tical discs, single or in pairs, occasionally connected by a thread of light; whilst, at another time, these nebule occur in forms of larger dimensions, and are either elongated, or variously branched, or fan-shaped, or appear like well-defined rings, enclosing a dark interior. It is conjectured that these bodies are undergoing variously developed formative processes, as the cosmical vapour becomes condensed in conformity with the laws of attraction, either round one or more of the nuclei. Between two and three thousand of such unresolvable nebulae, in which the most powerful telescopes have hitherto been unable to distinguish the presence of stars, have been counted, and their positions determined. The genetic evolution—that perpetual state of development ° | which seems to affect this portion of the regions of space— has led philosophical observers to the discovery of the analogy existing among organic phenomena. As in our forests we see the same kind of tree in all the various stages of its growth, and are thus enabled to form an idea of progressive, vital . development; so do we also in the great garden of the uni- verse recognise the most different phases of sidereal formation. The process of condensation, which formed a part of the. doctrines of Anaximenes, and of the Ionian School, appears to be going on before our eyes.. This subject of investigation and conjecture is especially attractive to the imagination, for in the study of the animated circles of nature, and of the F2 68 COSMOS. action of all the moving forces of the universe, the charm that exercises the most powerful influence on the mind is derived less from a knowledge of that which ¢s, than from a perception of that which ze// be, even though the latter be nothing more than a new condition of a known material existence; for of actual creation, of origin, the beginning of existence from non-existence, we haye no experience, and can therefore form no conception. A comparison of the various causes influencing the develop- ment manifested by the greater or less degree of condensation in the interior of nebule, no less than a successive course of direct observations have led to the belief that changes of form have been recognised first in Andromeda, next in the constellation Argo, and in the isolated filamentous portion of the nebula in Orion. But want of uniformity in the power of the instruments employed, different conditions of our atmo- sphere, and other optical relations, render a part of the results inyalid as historical evidence. Nebulous stars must not be confounded either with irregu- larly-shaped nebulous spots, properly so called, whose separate parts have an unequal degree of brightness (and which may perhaps become concentrated into stars as their circumference contracts), nor with the so-called planetary nebule, whose circular or slightly oval discs manifest in all their parts a perfectly uniform degree of faint light. Nebulous stars are not merely accidental bodies projected upon a nebulous ground, but are a part of the nebulous matter constituting one mass with the body which it surrounds. The not unfrequently con- siderable magnitude of their apparent diameter, and the remote distance from which they are revealed to us, show that both the planetary nebule and the nebulous stars must be of enormous dimensions. New and ingenious considera- tions of the different influence exercised by distance* on the intensity of light of a disc of appreciable diameter, and of a single sclf-lummous point, render it not improbable, that the planetary nebule are very remote nebulous stars, in which *The optical considerations relative to the difference presented by a single luminous point, and by a dise subtending an appreciable angle, in which the intensity of light is constant at every distance, are explained in Arago’s Analyse des Travaux de Sir William Herschel, (Annuaire du Bureau des Long., 1842, pp. 410-412, and 441.) CELESTIAL PHENOMENA. 69 the difference between the central body and the surrounding nebulous covering can no longer be detected by our telescopic instruments. _ The magnificent zones of the southern heavens, between 50° and 80°, are especially rich in nebulous stars, and in com- pressed unresolvable nebule. The larger of the two Mugel- lanic clouds, which circle round the starless, desert pole of the South, appears, according to the most recent researches,* as *£ a collection of clusters of stars, composed of globular clusters and nebule of different magnitude, and of large nebulous spots not resolvable, which producing a general brightness in the field of view, form as it were the back-ground of the picture.” The appearance of these clouds, of the brightly beaming con- stellation Argo, of the Milky Way between Scorpio, the Centaur and the Southern Cross, the picturesque beauty, if one may so speak, of the whole expanse of the Southern celestial hemisphere, has left upon my mind an ineffaceable impression. The zodiacal light which rises in a pyramidal form, and constantly contributes, by its mild radiance, to the external beauty of the tropical nights, is either a-vast nebulous ring, rotating between the Earth and Mars, or, less probably, the exterior stratum of the solar atmosphere. Besides these luminous clouds and nebule of definite form, exact and corres- ponding observations indicate the existence and the general distribution of an apparently non-luminous infinitely-divided matter, which possesses a force of resistance, and manifests its presence in Encke’s, and perhaps also in Biela’s comet, by diminishing their eccentricity and shortening their period of * The two Magellanic clouds, Nubecula major and Nubecula minor, are very remarkable objects. The larger of the two is an accumulated mass of stars, and consists of clusters of stars of irregular form, cither conical masses or nebulee of different magnitudes and degrees of con- densation. This is interspersed with nebulous spots, not resolvable into stars, but which are probably star dust, appearing only as a general radiance upon the telescopic field of a twenty-feet reflector, and forming a luminous ground on which other objects of striking and indescribable form are scattered. In no other portion of the heavens are so many nebulous and stellar masses thronged together in an equally small space. Nubecula minor is much less beautiful, has more unresolvable nebulous light, whilst the stellar masses are fewer and fainter in intensity —(From a letter of Sir John Herschel, Feldhuysen, Cape of Good Hope, 13th June, 1836.) 70 COSMOS. revolution. Of this impeding, etherial, and cosmical matter, it may be supposed that it is in motion; that it gravitates not- withstanding its original tenuity ; that it is condensed in the vicinity of the great mass of the Sun; and finally, that it may, for myriads of ages, have been augmented bv the vapour emanating from the tails of comets. If we now pass from the consideration of tne vaporous matter of the immeasurable regions of space (otpavod xdpros)*— whether, scattered without definite form and limits, it exists as a cosmical ether, or is condensed into nebulous spots and becomes comprised among the solid agglomerated bodies of | the universe—we approach a class of phenomena exclusivel designated by the term of stars, or as the sidereal world. Here, too, we find differences existing in the solidity or den- sity of the spheroidally agglomerated matter. Our own solar system presents all stages of mean density (or of the relation of volume to mass). On comparing the planets from Mercury to Mars with the Sun and with Jupiter, and these two last named with the yet inferior density of Saturn, we arrive, by a descending scale,—to draw our illustration from terrestrial substances,—at the respective densities of antimony, honey, - water, and pine wood. In comets, which actually constitute the most considerable portion of our solar system with respect to the number of individual forms, the concentrated part, usually termed the head, or nucleus, transmits sidereal light unimpaired. The mass of a comet probably in no case equals the five thousandth part of that of the earth, so dissimilar are * TI should have made use, in the place of garden of the universe, of the beautiful expression yépro¢ ofpavov, borrowed by Hesychius from an unknown poet, if ydproc had not rather signified in general an en closed space. The connexion with the German Garten, and the English gar- den, gards in Gothic (derived, according to Jacob Grimm, from gair- dan, to gird), is, however, evident, as is likewise the affinity with the Sclavonie grad, gorod, and as Pott remarks, in his Hiymol. For- schungen, th. i. s. 144 (Etymol. Researches), with the Latin chors, whence we have the Spanish corte, the French cour, and the English word court, together with the Ossetic khart. 'To these may be further added the Scandinavian gard*, gard, a place enclosed, as a court, or a country seat, and the Persian gerd, gird, a district, a circle, a princely country seat, a castle or city, as we find the term applied to the names of places in Firdusi’s Schahnameh, as Siyawakschgird, Darabgird, &e. * [This word is written gaard in the Danish.]—T7'*r CELESTIAL PHENOMENA. 71 the formative processes manifested in the original and per- haps still progressive agglomerations of matter. In proceed- ing from general to special considerations, it was particularly desirable to draw attention to this diversity, not merely as a possible, but as an actually proved fact. The purely speculative conclusions arrived at by Wright, Kant, and Lambert, concerning the general structural ar- rangement of the universe, and of the distribution of matter in space, have been confirmed by Sir William Herschel on the more certain path of observation and measurement. That at and enthusiastic, although cautious observer, was the first to sound the depths of heaven in order to determine the limits and form of the starry stratum which we inhabit; and he too was the first who ventured to throw the light of inves- tigation upon the relations existing between the position and distance of remote nebule and our own portion of the sidereal universe. William Herschel, as is well expressed in the ele- gant inscription on his monument at Upton, broke through the inclosures of heaven (celorum perrupit claustra), and, like another Columbus, penetrated into an unknown ocean, from which he beheld coasts and groups of islands, whose true posi- tion it remains for future ages to determine. ; Considerations regarding the different intensity of light in stars, and their relative number, that is to say, their nume- rical frequency on telescopic fields of equal magnitude, have led to the assumption of unequal distances and distribution in space in the strata which they compose. Such assumptions, in as far as they may lead us to draw the limits of the indi- vidual portions of the universe, cannot offer the same degree of mathematical certainty as that which may be attained in all that relates to our solar system, whether we consider the rotation of double stars with unequal velocity round one com- mon centre of gravity, or the apparent or true movements of all the heavenly bodies. If we take up the physical descrip- tion of the universe from the remotest nebule, we may be inclined to compare it with the mythical portions of history. The one begins in the obscurity of antiquity, the other in that of inaccessible space ; and at the point where reality seems to flee before us, imagination becomes doubly incited to draw from its own fulness, and give definite outline and permanence to the changing forms of objects. 72 COSMOS. If we compare the regions of the universe with one of the island-studded seas of our own planet, we may imagine mat- ter to be distributed in groups, either as unresolvable nebule of different ages, condensed around one or more nuclei, or as’ already agglomerated into clusters of stars, or isolated sphe- roidal bodies. The cluster of stars, to which our cosmical island belongs, forms a lens-shaped, flattened stratum, detached on every side, whose major axis is estimated at seven or eight hundred, and its minor one at a hundred and fifty times the distance of Sirius. It would appear, on the supposition’ that the parallax of Sirius is not greater than that accurately determined for the brightest star in the Centaur (0’-9128), that light traverses one distance of Sirius in three years, whilst it also follows from Bessel’s earlier excellent Memoir* on the parallax of the remarkable star 61 Cygni (0°:3483), (whose considerable motion might lead to the inference of great proximity), that a period of nine years and a quarter is required for the transmission of light from this star to our planet. Our starry stratum is a disc of inconsiderable thick- ness, divided a third of its length into two branches; it is supposed that we are near this division, and nearer to the , region of Sirius than to the constellation Aquila, almost in the middle of the stratum in the line of its thickness or minor axis. This position of our solar system, and the form of the whole * See Maclear’s “ Results from 1889 to 1840,” in the Trans. of the Astronomical Soc., vol. xii. p. 370, on a Centauri, the probable mean error being 0"°0640. For 61 Cygni, see Bessel, in Schumacher’s Jahr- buch, 1839, s. 47, and Schumacher’s Astron. Nachr., bd. xviii. s. 401, 402, probable mean error, 0"°0141. With reference to the relative distances of stars of different magnitudes, how those of the third mag- nitude may probably be three times more remote, and the manner in which we represent to ourselves the material arrangement of the starry strata, I have found the following remarkable passage in Kepler's Epitome Astronomie Copernicane, 1618, t. i. lib. 1, p. 34-39 :— “Sol hic noster nil aliud est quam una ex fixis, nobis major et clarior visa, quia propior quam fixa. Pone terram stare ad latus, una semi- diametro vie lactee, tunc hec via lactea apparebit circulus parvus, vel ellipsis parva, tota declinans ad latus alterum , eritque simul uno intuitu conspicua, que nunc non potest nisi dimidia conspicit quovis momento. Itaque fixarum sphera non tantum orbe stellarum, sed etiam circulo lactis versus nos deorsum est terminata,” SIDEREAL SYSTEMS. 13 discoidal stratum, have been inferred from sidereal scales, that is to say, from that method of counting the stars to which I have already alluded, and which is based upon the equidis- tant subdivision of the telescopic field of view. The relative depth of the stratum in all directions is measured by the reater or smaller number of stars appearing in each division. These divisions give the length of the ray of vision in the same manner as we measure the depth to which the plummet has been thrown, before it reaches the bottom, although in the case of a starry stratum there cannot, correctly speaking, be any idea of depth, but merely of outer limits. In the direc- tion of the longer axis, where the stars lie behind one another, the more remote ones appear closely crowded together, united, as it were, by a milky-white radiance, or luminous vapour, and are perspectively grouped, encircling as in a zone the visible vault of heaven. ‘This narrow and branched girdle, studded with radiant light, and here and there interrupted by dark spots, deviates only by a few degrees from forming a perfect large circle round the concave sphere of heaven, owing to our being near the centre of the large starry cluster, and almost on the plane of the Milky Way. If our planetary system were far outside this cluster, the Milky Way would appear to telescopic vision as a ring, and at a still greater distance as a resolvable discoidal nebula. Amongst the many self-luminous moving suns, erroneously called fixed stars, which constitute our cosmical island, our own sun is the only one known by direct observation to be a central body in its relations to spherical agglomerations of matter directly depending upon and revolving round it, either in the form of planets, comets, or aérolite-asteroids. As far as we have hitherto been able to investigate multiple stars (double stars or suns), these bodies are not subject, with respect to relative motion and illumination, to the same planetary dependence that characterizes our own solar system. wo or more self-luminous bodies, whose planets and moon, if such exist, have hitherto escaped our telescopic powers of vision, certainly revolve around one common centre of gravity ; but this is in a portion of space which is probably occupied merely by unagglomerated matter, or cosmical vapour, whilst in our system the centre of gravity is often comprised within the innermost limits of a visible central body. If, therefore, 74 COsMOS. we regard the Sun and the Earth, or the Earth and the Moon, as double stars, and the whole of our planetary solar system as a multiple cluster of stars, the analogy thus suggested must be limited to the universality of the laws of attraction in different systems, being alike applicable to the independent processes of light and to the method of illumination. For the generalization of cosmical views, corresponding with the plan we have proposed to follow in giving a delinea- tion of nature or of the universe, the solar system to which the Earth belongs may be considered in a twofold relation : firstly, with respect to the different classes of individually agglomerated matter, and the relative size, conformation, density, and distance of the heavenly bodies of this system ; and secondly, with reference to other portions of our s all and of the changes of position of its central body, the un. The solar system, that is to say, the variously formea matter circling round the Sun, consists according to the present state of our knowledge of eleven primary planets,* eighteen satellites, (Since the publication of Baron Humboldt’s work, in 1845, several other planets have been discovered, making the number of those be- longing to our planetary system sixteen instead of eleven. Of these, Astrea, Hebe, Flora, and Iris are members of the remarkable group of asteroids between Mars and Jupiter. Astrea and Hebe were discovered by Hencke at Driesen, the one in 1846 and the other in 1847; Flora and Iris were both discovered in 1847 by Mr. Hind, at the South Villa Observatory, Regent’s Park. It would appear from the latest determi- nations of their elements, that the small planets have the following order with respect to mean distance from the Sun: Flora, Iris, Vesta, Hebe, Astrea, Juno, Ceres, Pallas. Of these, Flora has the shortest period (about 3} years). 'The planet Neptune, which after having been predicted by several astronomers was actually observed on the 25th of September, 1846, is situated on the confines of our planetary system beyond Uranus. The discovery of this planet is not only highly interesting from the im- porta nee attached to it as a question of science, but also from the evidence it affords of the care and unremitting labour evinced by modern astro- nomers in the investigation and comparison of the older calculations, and the ingenious application of the results thus obtained to the obser- vation of new facts. The merit. of having paved the wey for the dis- covery of the planet Neptune is due to M. Bouvard, who in his perse- vering and assiduous efforts to deduce the entire orbit of Uranus from observa tions made during the forty years that succeeded the discovery of that planet in 1781, found the results yielded by theory to be at vari- ance with fact, in a degree that had no parallel in the history ef astro- PLANETARY SYSTEMS. 75 or secondary planets—and myriads of comets, three of which, known as the “planetary comets,’’ do not pass beyond the narrow limits of the orbits described by the principal planets. We may, with no inconsiderable degree of probability, include within the domain of our Sun, in the immediate sphere of its central force, a rotating ring of vaporous matter, lying pro- bably between the orbits of Venus and Mars, but certainly nomy. This startling discrepancy, which seemed only to gain additional weight from every attempt made by M. Bouvard to correct his calcula- tions, led Leverrier, after a careful modification of the tables of Bouvard, to establish the proposition that there was “a formal incompatibility be- tween the observed motions of Uranus and the hypothesis that he was acted on only by the Sun and known planets, according to the law of universal gravitation.” Pursuing this idea, Leverrier arrived at the conclusion that the disturbing cause must be a planet, and finally, after an amount of labour that seems perfectly overwhelming, he, on the 31st of August, 1846, laid before the French Institute a paper, in which he indicated the exact spot in the heavens where this new planetary body would be found, giving the following data for its various elements: mean distance from the Sun, 367154 times that of the Earth; period of revolution, 217°387 years; mean long., Jan. Ist, 1847, 318° 47’; mass, gaz; heliocentric long., Jan. 1, 1847, 326° 32’. Essential difficulties still intervened, however, and as the remoteness of the planet rendered it improbable that its disc would be discernible by any telescopic instru- ment, no other means remained for detecting the suspected body but its planetary motion, which could only be ascertained by mapping, after every observation, the quarter of the heavens scanned, and by a com- parison of the various maps. Fortunately for the verification of Le- yerrier’s predictions, Dr. Bremiker had just completed a map of the precise region in which it was expected the new planet would appear, this being one of a series of maps made for the Academy of Berlin, of the small stars along the entire zodiac. By means of this valuable assistance, Dr. Galle, of the Berlin Observatory, was led, on the 25th of September, 1846, by the discovery of a star of the eighth magnitude, not recorded in Dr. Bremiker’s map, to make the first observation of the planet predicted by Leverrier. By a singular coincidence, Mr. Adams of Cambridge, had predicted the appearance of the planet simultaneously with M. Leverrier ; but by the concurrence of several circumstances much to be regretted, the world at large were not made acquainted with Mr. Adams’ yaluable discovery until subsequently to the period at which Leverrier published his observations. As the data of Leverrier and Adams stand at present there is a discrepancy between the redicted and the true distance, and in some other elements of the planet; it remains, therefore, for these or future astronomers to reconcile theory with fact, or perhaps, as in the case of Uranus, to make the new planet the means of leading to yet greater discoveries. It would appear from 76 COSMOS. beyond that of the Earth,* which appears to us in a pyramidal form, and is known as the Zodiacal Light; and a host of very small asteroids, whose orbits either intersect, or very nearly approach that of our earth, and which present us with the phenomena of aérolites and falling or shooting stars. When we consider the complication of variously formed bodies which revolve round the Sun in orbits of such dissimilar eccentricity —although we may not be disposed, with the immortal author of the Mécanique Céleste, to regard the larger number of comets as nebulous stars, passing from one central system to another, we yet cannot fail to acknowledge that the planetary system, especially so called, (that is, the group of heavenly bodies which, together with their satellites, revolve with but slightly eccentric orbits round the Sun,) constitutes but a small por- tion of the whole system with respect to individual numbers, if not to mass, It has been proposed to consider the telescopic planets, Vesta, Juno, Ceres, and Pallas, with their more closely inter- secting, inclined, and eccentric orbits, as a zone of separation, or asa middle group in space; and if this view be adopted, we shall discover that the interior planetary group (consisting of Mercury, Venus, the Earth, and Mars,) presents several very striking contrasts} when compared with the exterior group, comprising Jupiter, Saturn, and Uranus. The planets nearest the most recent observations, that the mass of Neptune, instead of being, as at first stated, 5/,, is only about ,,!,, that of the Sun, whilst its periodic time is now given with a greater probability at 166 years, and its mean distance from the Sun nearly 30. The planet appears to have a ring, but as yet no accurate observations have been made regard- ing its system of satellites. See 7'rans. Astron. Soc., and The Planet Neptune, 1848, by J. P. Nicholl.J—7'r. * “Tf there should be molecules in the zones diffused by the atmo- sphere of the Sun of too volatile a nature either to combine with one another or with the plancts, we must suppose that they would in circling round that luminary present all the appearances of zodiacal light, with- out opposing any appreciable resistance to the different bodies com- posing the planetary system, either owing to their extreme rarity, or to the similarity existing between their motion and that of the planets with which they come in contact.”—Laplace, Hxpos. du Syst. du Monde, (ed. 5.) p. 415. + Laplace, Hxp. du Syst. du Monde, pp. 396, 414, t Littrow, Astronomic, 1825, bd. xi. § 107. Midler, Astron, 1841, § 212. Laplace, Hap. du Syst. du Monde, p. 210. PLANETARY SYSTEMS. , ee the Sun, and consequently included in the inner group, are of more moderate size, denser, rotate more slowly and with nearly equal velocity, (their periods of revolution being almost all about 24 hours,) are less compressed at the poles, and, with the exception of one, are without satellites. The exterior planets, which are further removed from the Sun, are very considerably larger, have a density five times less, more than twice as great a velocity in the period of their rotation round their axes, are more compressed at the poles, and if six satellites may be ascribed to Uranus, have a quantitative preponderance in the number of their attendant moons, which is as seventeen to one. Such general considerations regarding certain characteristic properties appertaining to whole groups, cannot, however, be applied with equal justice to the individual planets of every group; nor to the relations between the distances of the re- ‘volving planets from the central body, and their absolute size, density, period of rotation, eccentricity, and the inclination of their orbits and the axes. We know as yet of no inherent necessity, no mechanical natural law, similar to the one which teaches us that the squares of the periodic times are proportional to the cubes of the major axes, by which the above-named six elements of the planetary bodies and the form of their orbit are made dependent either on one another, ‘or on their mean distance from the Sun. Mars is smaller than the Earth and Venus, although further removed from the Sun than these last-named planets; approaching most nearly in size to Mercury, the nearest planet to the Sun. Saturn is smaller than Jupiter, and yet much larger than Uranus. The zone of the telescopic planets, which have so inconsiderable a volume, immediately precede Jupiter, (the greatest in size of any of the planetary bodies,) if we consider them with regard to distance from the Sun; and yet the discs of these small asteroids, which scarcely admit of measurement, have an areal surface not much more than half that of France, Madagascar, or Borneo. However striking may be the extremely small density of all the colossal planets, which are furthest removed from the Sun, we are yet unable in this respect to recognise any regular succession.* Uranus appears to be denser than Saturn, -* See Kepler, on the increasing density and volume of the planets in proportion with their increase of distance from the Sun, which isdescribed “ es 7}. ae COSMOS. even 1f we adopt the smaller mass, 74,5, assumed by Lamont; and notwithstanding the inconsiderable difference of density observed in the innermost planetary group,* we find both Venus and Mars less dense than the Earth, which lies between them. The time of rotation certainly diminishes with increasing ‘solar distance, but yet it is greater in Mars than in the Earth, and in Saturn than in Jupiter. The elliptic orbits of Juno, Pallas, and Mercury, have the greatest degree of eccentricity, . and Mars and Venus, which immediately follow each other, haye the least. Mercury and Venus exhibit the same con- trasts that may be observed in the four smaller planets, or asteroids, whose paths are so closely interwoven. _ The eccentricities of Juno and Pallas are very nearly iden- tical, and are each three times as great as those of Ceres and Vesta. The same may be said of the inclination of the orbits of the planets towards the plane of projection of the ecliptic, or in the position of their. axes of rotation with relation to their orbits, a position on which the relations of climate, seasons of the year, and length of the days depend more than on eccentricity. Those planets that have the most elongated elliptic orbits, as Juno, Pallas, and Mercury, have also, although not to the same degree, their orbits most strongly inclined towards the ecliptic. Pallas has a comet-like incli- nation nearly twenty-six times greater than that of Jupiter, whilst in the little planet Vesta, which is so near Pallas, the angle of inclination scarcely by six times exceeds that of Jupiter. n equally irregular succession is observed in the position of the axes of the few planets (four or five) whose planes of rotation we know with any degree of certainty. It would ap- pear from the position of the satellites of Uranus, two of which, the second and fourth, have been recently observed with cer- tainty, that the axis of this, the outermost of all the planets, is scarcely inclined as much as 11° towards the plane of its orbit, while Saturn is placed between this planet, whose axis almost as the densest of all the heavenly bodies; in the Hpitome Astron. Co- pern. in vii. libros digesta, 1618-1622, p. 420. Leibnitz also inclined to the opinions of Kepler and Otto von Guericke, that the planets in- crease in volume in proportion to their increase of distance from the Sun. See his letter to the Magdeburg Burgomaster (Mayence, 1671), ia Leibnitz, Deutschen Schriften, herausg. von Guhraver, th. i. § 264. * On the arrangement of masses, see Encke, in Schum, Astr. Nachr. 1843, Nr. 488, § 114. PLANETARY SYSTEMS. 79 coincides with the plane of its orbit, and Jupiter, whose axis of rotation is nearly perpendicular to it. In this enumeration of the forms which compose the world in space, wé have delineated them as possessing an actual ex- istence, and not as objects of intellectual contemplation, or as mere links of a mental and causal chain of connexion. The planetary system in its relations of absolute size, and relative position of the axes, density, time of rotation, and different degrees of eccentricity of the orbits, does not appear to offer to our apprehension any stronger evidence of a natural neces- sity than the proportion observed in the distribution of land and water on the Earth, the configuration of continents, or the height of mountain chains. In these respects we can dis- cover no common law in the regions of space or in the ine- qualities of the earth’s crust. They are facts in nature, that have arisen from the conflict of manifold forces acting under unknown conditions; although man considers as accidental whatever he is unable to explain in the planetary formation on purely genetic principles. If the planets have been formed out of separate rings of vaporous matter revolving round the Sun, we may conjecture that the different thickness, unequal density, temperature, and electro-magnetic tension of these rings may have given occasion to the most various agglomera- tions of matter, in the same manner as the amount of tangential velocity and small variations in its direction have produced. so great a difference in the forms and inclinations of the elliptic orbits. Attractions of mass and laws of gravitation have no doubt exercised an influence here, no less than in the ' geognostic relations of the elevations of continents; but we are unable from present forms to draw any conclusions regard- ing the series of conditions through which they have passed. Even the so-called law of the distances of the planets from the Sun, the law of progression, (which led Kepler to conjec- ture the existence of a planet supplying the link that was wanting in the chain of connexion between Mars and Jupiter) has been found numerically inexact for the distances between Mercury, Venus, and the Earth, and at variance with the con- ception of a series owing to the necessity for a supposition in the case of the first member. The hitherto discovered principal p.anets that revolve round our Sun, are attended certainly by fourteen, and probably ~ 80 COSMOS. by eighteen secondary planets (moons or satellites). The principal planets are therefore themselves the central bodies of subordinate systems. We seem to recognise in the fabric of the universe the same process of arrangement so frequently exhibited in the development of organic life, where we find in the manifold combinations of groups of plants or animals, the same typical form repeated in the subordinate classes. The secondary planets or satellites are more frequent in the ex- ternal region of the planetary system, lying beyond the inter- secting orbits of the smaller planets or asteroids ; in the inner region none of the planets are attended by satellites, with the exception of the Earth, whose moon is relatively of gveat magnitude, since its diameter is equal to a fourth of that of the Earth; whilst the diameter of the largest of al) known secondary planets—the sixth satellite of Saturn—is probably about one-seventeenth, and the largest of Jupiter’s moons, the third, only about one twenty-sixth part that of the primary planet or central body. The planets which are attended by ‘the largest number of satellites are most remote from the Sun, and are at the same time the largest, most compressed at the poles, and the least dense. According to the most recent measurements of Madler, Uranus has a greater plane- -tary compression than any other of the planets, viz. 54,4. In our Earth and her moon, whose mean distance from one another amounts to 207,200 miles, we find that the differences of mass* and diameter between the two are much less con- siderable than are usually observed to exist between the principal planets and their attendant satellites, or between bodies of different orders in the solar system. Whilst the density of the Moon is five-ninths less than that of the Earth, it would appear, if we may sufficiently depend upon the determinations of their magnitudes and masses, that the * Tf, according to Burckhardt’s determination, the Moon’s radius be 0°2725 and its volume j54;5, its density will be 0°5596, or nearly five- ninéhs. Compare also Wilh. Beer und H. Midler, der Mond, § 2, 10, and Midler, Ast., § 157. The material contents of the Moon are, according to Hausen, nearly s, (and according to Miidler ,,;) that of the Earth; and its mass equal to ;,4,; that of the Earth. In the largest of Jupiter’s moons, the third, the relations of volume to the central body are yx}4;; and of mass 3,45. On the polar flattening of Uranus, see Schum. Astron. Nachr., 1844, Nr. 493, PLANETARY SYSTEMS, 8k second of Jupiter’s moons is actually denser than that great planet itself. Amongst the fourteen satellites, that have been investigated with any degree of certainty, the system of the seven satellites of Saturn presents an instance of the greatest possible contrast, both in absolute magnitude, and in distance from the central body. The sixth of these satellites is probably not much smaller than Mars, whilst our moon has a diameter which does not amount to more than half that of the latter planet. With respect to volume, the two outer, the sixth and seventh of Saturn’s satellites, approach the nearest to the third and brightest of Jupiter's moons. ‘The two innermost of these satellites belong perhaps, together with the remote moons of Uranus, to the smallest cosmical bodies of our solar systein, being only made visible under favourable cireum- stances by the most powerful instruments. They were first discovered by the forty-foot telescope of William Herschel in 1789, and were seen again by John Herschel at the Cape of Good Hope, by Vico at Rome, and by Lamont at Munich. Determinations of the ¢rwe diameter of satellites, made by the measurement of the apparent size of their small discs, are sub- jected to many optical difficulties ; but numerical astronomy, whose task it is to predetermine by calculation the motions of the heavenly bodies as they will appear when viewed from the Earth, is directed almost exclusively to motion and mass, and but little to volume. The absolute distance of a satellite from its central body is greatest in the case of the outermost or seventh satellite of Saturn, its distance from the body round which it revolves amounting to more than two millions of miles, or ten times as great a distance as that of our moon from the Earth. In the case of Jupiter we find that the outermost or fourth attendant moon is only 1,040,000 miles from that planet, whilst the distance between Uranus and its sixth satellite (if the latter really exist) amounts to as much as 1,360,000 miles. If we compare, in each of these subordi- nate systems, the volume of the main planet with the distance of the orbit of its most remote satellite, we discover the exis- tence of entirely new numerical relations. The distances of the outermost satellites of Uranus, Saturn and Jupiter are, when expressed in semi-diameters of the main plancts, as 91, 64, and 27. The outermost satellite of Saturn appears, therefore, to be remoyed only about one-fifteenth further from d 82 COSMOS. the centre of that planet than our moon is from the Earth. The first or innermost of Saturn’s satellites is nearer to its central body than any other of the secondary planets, and pre- sents moreover the only instance of a period of revolution of less than twenty-four hours. Its distance from the centre of Saturn may, according to Madler and Wilhelm Beer, be ex- pressed as 2°47 semi-diameters of that planet, or as 80,088 miles. Its distance from the surface of the main planet is therefore 47,480 miles, and from the outermost edge of the ring only 4916 miles. The traveller may form to himself an estimate of the smallness of this amount by remembering the statement of an enterprising navigator, Captain Beechey, that he had in three years passed over 72,800 miles. If instead of absolute distances we take the semi-diameters of the principal planets, we shall find that even the first or nearest of the moons of Jupiter (which is 26,000 miles further removed from the centre of that planet than our moon is from that of the Earth) is only six semi-diameters of Jupiter from its centre, whilst our moon is removed from us fully 601 semi-diameters of the Earth. In the subordinate systems of satellites we find that the same laws of gravitation which regulate the revolutions of the principal planets round the Sun, likewise govern the mutual relations existing between these planets among one another, and with reference to their attendant satellites. The twelve moons of Saturn, Jupiter, and the Earth, all move like the primary planets from west to east, and in elliptic orbits, deviating but little from circles. It is only in the case of our moon, and perhaps in that of the first and innermost of the satellites of Saturn (0°068) that we discover an eccentricity greater than that of Jupiter; according to the very exact observations of Bessel, the eccentricity of the sixth of Saturn’s satellites (0°029) exceeds that of the Earth. On the extremest limits of the planetary system, where, at a distance nineteen times greater than that of our Earth, the centripetal force of the Sun is greatly diminished, the satellites of Uranus (which have certainly been but imperfectly investigated) exhibit the most striking contrasts from the facts observed with regard to other secondary planets. Instead, as in all other satellites, of having their orbits but slightly inclined towards the ecliptic, and (not excepting even Saturn’s ring, which may be regarded PLANETARY SYSTEMS. 83 as a fusion of agglomerated satellites) moving from west to east, the satellites of Uranus are almost perpendicular to the ecliptic, and move retrogressively from east to west, as Sir John Herschel has proved by observations continued during many years. Ifthe primary and secondary planets have been formed by the condensation of rotating rings of solar and planetary atmospheric vapour, there must have existed singular causes of retardation or impediment in the vaporous rings revolving round Uranus, by which, under relations with which we are unacquainted, the revolution of the second and fourth of its satellites was made to assume a direction opposite to that of the rotation of the central planet. It seems highly probable that the period of rotation of al/ secondary planets is equal to that of their revolution round the main planet, and therefore that they always present to the latter the same side. Inequalities, occasioned by slight vari- ations in the revolution, give rise to fluctuations of from 6° to 8°, or to an apparent libration in longitude as well as in latitude. Thus, in the case of our moon, we sometimes observe more than the half of its surface, the eastern and northern edges being more visible at one time, and the western or southern at another. By means of this libration* we are enabled to see the annular mountain Malapert (which occa- sionally conceals the Moon’s south pole), the arctic landscape round the crater of Gioja, and the large gray plane near Endymion, which excceds in superficial extent the Mare Vaporum. 'Three-sevenths of the Moon’s surface are entirely concealed from our observation, and must always remain so, unless new and unexpected disturbing causes come into play. These cosmical relations involuntarily remind us of nearly similar conditions in the intellectual world, where, in the domain of deep research into the mysteries and the primeval creative forces of nature, there are regions similarly turned away from us, and apparently unattainable, of which only a narrow margin has revealed itself, for thousands of years, to the human mind, appearing, from time to time, either glim- mering in true or delusive light. We have hitherto con- sidered the primary planets, their satellites, and the concentric * Beer and Miidler, op. cit., § 185, s. 208, and § 347, s. 832; and in their Phys. Kenntniss der himmt Kérper. s. 4 und 69, Tab. 1, (Phy- sical History of the Heavenly Bodies.) ; G2 84 COSMOS. rings which belong to one at least of the outermost planets, as products of tangential force, and as closely connected together by mutual attraction; it, therefore, now only re- mains for us to speak of the unnumbered host of comets which constitute a portion of the cosmical bodies revolving in inde- pendent orbits round the Sun. If we assume an equable distribution of their orbits, and the limits of their perthelia, or greatest proximities to the Sun, and the possibility of their remaining invisible to the inhabitants of the Earth, and base our estimates on the rules of the calculus of probabilities, we shall obtain as the result an amount of myriads perfectly astonishing. Kepler, with his usual animation of expression, said, that there were more comets in the regions of space than fishes in the depths of ocean. As yet, however, there are scarcely one hundred and fifty, whose paths have been caicu- lated, if we may assume at six or seven hundred the number of comets, whose appearance and passage through known constellations have been ascertained by more or less precise observations. Whilst the so-called classical nations of the west, the Greeks and Romans, although they may occasionally have indicated the position in which a comet first appeared, never aiford any information regarding its apparent path, the copious literature of the Chinese (who observed nature care- fully, and recorded with accuracy what they saw) contains circumstantial notices of the constellations through which each comet was observed to pass. These notices go back to more than five hundred years before the Christian era, and many of them are still found to be of value in astronomical observa- tions.* * The first comets of whose orbits we have any knowledge, and which were calculated from Chinese ob-ervations, are those of 240 (under Gordian iIl.), 539 (under Justinian), 565, 568, 574, 837, 1337, and 1385. See John Russell Hind in Schum. Astr. Nachr., 1843. No. 498. Whilst the comet of 837 (which, according to du Séjour, continued during 24 hours within a distance of 2,000,000 miles from the Earth) terrified Louis I. of France to that degree, that he busied himself in building churches and founding monastic establishments, in the hope of ap- peasing the evils threatened by its appearance, the Chinese astrono- mers made observations on the path of this cosmical body, whose tail extended over a space of 60°, appearing sometimes single and some- times multiple. The first comet that has been calculated solely from European observations was that of 1456, known as Halley’s comet, from the belief long, but erroneously entertained, that the period when gg COMETS. 85 Although comets have a smaller mass than any other cos- mical bodies—being, according to our present knowledge, probably not equal to zq'5q part of the Earth’s mass—yet they occupy the largest space, as their tails in several instances extend over many millions of miles. The cone of luminous vapour which radiates from them has been found, in some eases (as in 1680 and 1811), to equal the length of the Earth’s distance from the Sun, forming a line that intersects both the orbits of Venus and Mercury. It is even probable that the vapour of the tails of comets mingled with our atmosphere in the years 1819 and 1823. Comets exhibit such diversities of form, which appear rather to appertain to the individual than the class, that a description of one of these ‘“ wandering light-clouds,” as they were already called by Xenophanes and Theon of Alexandria, contemporaries of Pappus, can only be applied with caution to another. The faintest telescopic comets are generally deyoid of visible tails, and resemble Herschel’s nebulous stars. They appear like circular nebule of faintly-glimmering vapour, with the light concentrated towards the middle. This is the most simple type; but it cannot, however, be regarded as rudimentary, since it might equally be the type of an older cosmica! body, exhausted by exhalation. In the larger comets we may distinguish both the so-called ‘“ head ” or “nucleus,” and the single or multiple tail, which is charac- teristically denominated by the Chinese astronomers “ the brush.”’ (sz?.) The nucleus generally presents no definite out- line, although, in a few rare cases, it appears like a star of the first or second magnitude, and has even been seen in bright sunshine ;* as, for instance, in the large comets of 1402, 1532, 1577, 1744, and 1848. This latter circumstance indicates. in particular individuals, a denser mass, capable of reflecting light with greater intensity. Even in Herschel’s large tele- it was first observed by that astronomer was its first and only well attested appearance, See Arago, in the Annuaire, 1836, p. 204, and Laugier, Comptes rendus des Séances de l Acad., 1843, t. xvi. 1006. * Arago, Annuaire, 1832, pp. 209,211. The phenomenon of the tail of a comet being visible in bright sunshine, which is recorded of the comet of 1402, occurred again in the case of the large comet of 1843, _whose nucleus and tail were seén in North America, on the 28th of February (according to the testimony of J. G. Clarke, of Portland, 86 COSMOS. scope only two comets, that discovered in Sicily, in 1807, and the splendid one of 1811, exhibited well-defined discs ;* the one at an angle of 1”, and the other at 0"-77, whence the true diameters are assumed to be 536 and 428 miles. The dia- meters of the less well defined nuclei of the comets of 1798 and 1805 did not appear to exceed 24 or 28 miles. In several comets that have been investigated with great care, especially in the above-named one of 1811, which con- tinued visible for so long a period, the nucleus and its nebulous envelope were entirely separated from the tail by a darker space. The intensity of light in the nucleus of comets does not augment towards the centre in any uniform degree; brightly shining zones being in many cases separated by concentric nebulous envelopes. The tails sometimes appear single, sometimes, although more rarely, double; and in the comets of 1807 and 1843 the branches were of different lengths; in one instance (1744) the tail had six branches, the whole forming an angle of 60°. The tails have been some- times straight, sometimes curved, either towards both sides, or towards the side appearing to us as the exterior (as in. 1811), or convex towards the direction in which the comet is moving (as in that of 1618); and sometimes the tail has even appeared like aflame in motion. The tails are always turned away from the sun, so that their line of prolongation passes through its centre; a fact which, according to Edward Biot, was noticed by the Chinese astronomers as early as 837, but was first generally made known in Europe by Fracastoro and Peter Apian, in the sixteenth century. These emanations may be regarded as conoidal envelopes of greater or less thickness, State of Maine), between 1 and 3 o’clock in the afternoon. The distance of the very dense nucleus from the sun’s light admitted of being measured with much exactness. The nucleus and tail appeared like a very pure white cloud, a darker space intervening between the tail and the nucleus. (Amer. Journ. of Science. vol. xlv. No. 1., p. 229.) «(The translator was at New Bedford, Massachusetts, U.S., on the 28th February, 1843, and distinctly saw the comet, between 1 and 2 in the afternoon. The sky at the time was intensely blue, and the sun shining with a dazzling brightness unknown in European climates. |}—7'r. * Phil. Trans. for 1808, Part IT. p. 155, and for 1812, Part I. p. 118. The diameters found by Herschel for the nuclei were 538 and 428 English miles. For the magnitudes of the comets of 1798 and 1805 see Arago, Annuaire, 1832, p. 203. COMETS. 87 and considered in this manner, they furnish a simple expla- nation of many of the remarkable optical phenomena already spoken of. | . Comets are not only characteristically different in form, some being entirely without a visible tail, whilst others have a tail of immense length (as in the instance of the comet of 1618, whose tail measured 104°), but we also see the same comets undergoing successive and rapidly changing processes of configuration. These variations of form have been most accurately and admirably described in the comet of 1744, by Hensius, at St. Petersburgh, and in Halley’s comet, on its last reappearance in 1835, by Bessel, at Konigsberg. A more or less well-defined tuft of rays emanated from that part of the nucleus which was turned towards the Sun ; and the rays being bent backwards, formed a part of the tail. The nucleus of Halley’s comet, with its emanations, presented the appear- ance of a burning rocket, the end of which was turned side- ways by the force of the wind. The rays issuing from the head were seen by Arago and myself, at the Observatory at Paris, to assume very different forms on successive nights.* The great K6nigsberg astronomer concluded from many measurements, and from theoretical considerations, “ that the cone of light issuing from the comet deviated considerably both to the right and the left of the true direction of the Sun, but that it always returned to that direction, and passed over to the opposite side, so that both the cone of light and the body of the comet from whence it emanated, experienced a rotatory, or rather a vibratory motion, in the plane of the orbit.” He finds that “the attractive force exercised by the Sun on heavy bodies, is inadequate to explain such vibra- tions, and is of opinion that they indicate a polar force, which turns one semi-diameter of the comet towards the Sun, and strives to turn the opposite side away from that luminary. The magnetic polarity possessed by the Earth, may present some analogy to this; and, should the Sun have an opposite polarity, an influence might be manifested, resulting in the precession of the equinoxes.” This is not the place to enter * Arago, Des changements physiques de la Cométe de Halley du 15-23 Oct., 1885. Annuaire, 1836, pp. 218, 221. The ordinary direction of the emanations was noticed evenin Nero’s time. “Come radios solis effugiunt.” Seneca, Nat. Quest., vii. 20. 88 COSMOS. more fully upon the grounds on which explanations of this subject have been based; but observations so remarkable,* and views of so exalted a character, regarding the most won- derful class of the cosmical bodies belonging to our solar system, ought not to be entirely passed over in this sketch of a general picture of nature. Although as arule the tails of comets increase in magnitude and brilliancy in the vicinity of the sun, and are directed away from that central body, yet the comet of 1823 offered the remarkable example of two tails, one of which was turned towards the sun, and the other away from it, forming with each other an angle of 160°. Modifications of polarity and the unequal manner of its distribution, and of the direction in which it is conducted, may in this rare instance have occasioned a double, unchecked, continuous emanation of nebulous matter. Aristotle, in his Natural Philosophy, makes these emana- tions the means of bringing the phenomena of comets into a singular connection with the existence of the Milky Way, According to his views, the innumerable quantity of stars which compose this starry zone give out a self-luminous, in- candescent matter. The nebulous belt which separates the different portions of the vault of heaven, was, therefore, regarded by the Stagirite as a large comet, the substance of which was incessantly being renewed. } | * Bessel, in Schumacher, Ast. Nachr., 1836, Nr. 300-302, s. 188, 192,197, 200, 202, und 230. Also in Schumacher, Jahrb., 1837, 8s. 149, 168. William Herschel, in his observations on the beautiful comet of 1811, believed that he had discovered evidences of the rotation of the nucleus and tail (Phil. Trans. for 1812, Part L., p. 140). Dunlop, at Paramatta, thought the same with reference to the third comet of 1825. + Bessel, in Ast. Nachr., 1836, No. 302, s. 231. Schum., Jahrb. 1837, s.175. Seealso Lehmann, Ueber Cometenschweife (On the Tails of Comets), in Bode, Astron. Jahrb. fiir 1826, s. 168. t Aristot. Meteor., i. 8, 11-14, und 19-21 (ed. Ideler, t. i., pp. 32-34). Biese, Phil. des Aristoteles, bd. ii. s. 86. Since Aristotle exercised so great an influence throughout the whole of the middle ages, it is very much to be regretted that he was so averse to those grander views of the elder Pythagoreans, which inculcated ideas so nearly approximating to truth, respecting the structure of the universe. He asserts that comets are transitory meteors belonging to our atmosphere, in the very book in which he cites the opinion of the Pythagorean school, according to which these cosmical bodies are supposed to be planets, having long COMETS. 89 The occultation of the fixed stars by the nucleus of a comet, or by its innermost vaporous envelopes, might throw some light on the physical character of these wonderful bodies ; but we are unfortunately deficient in observations by which we may be assured* that the occultation was perfectly central ; for, as it has already been observed, the parts of the envelope contiguous to the nucleus are alternately composed of layers of dense or very attenuated vapour. On the other hand, the carefully conducted measurements of Bessel prove, beyond all doubt, that on the 29th of September, 1835, the light of a star of the tenth magnitude, which was then at a distance of 7-78 from the central point of the head of Halley's comet, passed through very dense nebulous matter, without experi- periods of revolution. (Aristot., i. 6,2.) This Pythagorean doctrine,which, according to the testimony of Apollonius Myndius, was still more ancient, having originated with the Chaldeans, passed over to the Romans, who in this instance, as was their usual practice, were merely the copiers of others. The Myndian philosopher describes the path of comets as directed towards the upper and remote regions of heaven. Hence Seneca says, in his Vat. Quest., vii. 17 : “ Cometes non est species falsa, sed proprium sidus sicut solis et lune: altiora mundi secat et tunc demum apparet quum in imum cursum sui venit ;” and again, (at vii. 27,) “ Cometes awternos esse et sortis ejusdem, cujus caetera (sidera), etiamsi faciem illis non habent similem.’ Pliny (ii. 25) also refers to Apollonius Myndius, when he says: “ Sunt qui et hec sidera perpetua esse credant suoque ambitu ire, sed non nisi relicta a sole cerni.” * Olbers, in Ast. Nachr., 1828, s. 157, 184. Arago, De la Constitution physique des Cométes ; Annuaire de 1832, p. 203,208. The ancients were struck by the phenomenon that it was possible to see through comets as through a flame. The earliest evidenve to be met with of stars having been seen through comets, is that of Democritus, (Aristot., Meteor., i. 6, 11,) and the statement leads Aristotle to make the not unimportant remark, that he himself had observed the occultation of one of the stars of Gemini by Jupiter. Seneca only speaks decidedly of the transparence of the tail of comets. ‘“ We may see,” says he, “stars through a comet as through a cloud (Wat. Quest., vii. 18) ; but we can only see through the rays of the tail, and not through the body of the comet itself: non in ea parte qua sidus ipsum est spissi et solidi ignis, sed qua rarus splendor occurrit et in crines dispergitur. Per intervalla ignium, non per ipsos, vides.” (vii. 26.) The last remark is unnecessary, since, as Galileo observed in the Saggiatore (Letiera a Monsignor Cesarini, 1619), we can certainly see through a flame when it is not of too great a, thickness, > 90 COSMOS. encing any deflection during its passage.* If such an absence of refracting power must be ascribed to the nucleus of a comet, we can scarcely regard the matter composing comets as a gaseous fluid. The question here arises, whether this absence of refracting power may not be owing to the extreme tenuity of the fluid? or does the comet consist of separated particles, constituting a cosmical stratum of clouds, which, like the clouds of our atmosphere, that exercise no influence on the zenith distance of the stars, does not affect the ray of light passing through it? In the passage of a comet over a star, a more or less considerable diminution of light has often been observed: but this has been justly ascribed to the brightness of the ground from which the star seems to stand forth during the passage of the comet. The most important and decisive observations that we possess on the nature and the light of comets, are due to Arago’s polarization experiments. His polariscope instructs us regarding the physical constitution of the Sun and comets, indicating whether a ray that reaches us from a distance of many millions of miles, transmits light directly, or by reflec- tion; and if the former, whether the source of light is a solid, a liquid, or a gaseous body. His apparatus was used at the Paris Observatory, in examining the light of Capella, and that of the great comet of 1819. The latter showed polarized, and therefore reflected light, whilst the fixed star, as was to be expected, appeared to be a self-luminous sun.t} * Bessel, in the Astron. Nachr., 1836, No. 301, s. 204, 206. Struve, in Recueil des Mém. de l’ Acad. de St. Petersb., 1836, p. 140, 143, and Astr. Nachr., 1836, No. 303, s. 238, writes as follows: “ At Dorpat the star was in conjunction only 2"°2 from the brightest point of the comet. The star remained continually visible, and its light was not perceptibly diminished whilst the nucleus of the comet seemed to be almost ex- tinguished before the radiance of the small star of the ninth or tenth magnitude.” + On the 3d of July, 1819, Arago made the first attempt to analyse the light of comets by polarization, on the evening of the sudden ap- pearance of the great comet. I was present at the Paris Observatory, and was fully convinced, as were also Matthieu and the late Bouvard, of the dissimilarity in the intensity of the light seen in the polariscope, when the instrument received cometary light. When it received light from Capella, which was near the comet, and at an equal altitude, the images were of equal intensity. On the reappearance of Halley’s comet, in 1835, the instrument was altered, so as to give, according to Arago’s COMETS. 9] The existence of polarized cometary light announced itself not only by the inequality of the images, but was proved with greater certainty on the reappearance of Halley’s comet, in the year 1835, by the more striking contrast of the comple- mentary colours, deduced from the laws of chromatic polar- ization discovered by Arago in 1811. These beautiful ex- periments still leave it undecided, whether, in addition to this reflected solar light, comets may not have light of their own. Even in the case of the planets, as, for instance, in Venus, an evolution of independent light seems very probable. The variable intensity of light in comets cannot always be explained by the position of their orbits, and their distance from the Sun. It would seem to indicate, in some individuals, the existence of an inherent protvess of condensation, and an increased or diminished capacity of reflecting borrowed light. In the comet of 1618, and in that which has a period of three years, it was observed first by Hevelius, that the nucleus of the comet diminished at its perihelion, and enlarged at its aphelion, a fact which, after remaining long unheeded, was again noticed by the talented astronomer, Valz, at Nismes. The regularity of the change of volume, according to the different degrees of distance from the Sun, appears very striking. The physical explanation of the phenomenon can- not, however, be sought in the condensed layers of cosmical vapour occurring in the vicinity of the Sun, since it is difficult to imagine the nebulous envelope of the nucleus of the comet to be vesicular and impervious to the ether.* The dissimilar eccentricity of the orbits of comets has, in recent times (1819), in the most brilliant manner enriched our knowledge of the solar system. Encke has discovered the existence of a comet of so short a period of revolution, chromatic polarization, two images of complementary colours (green and red). (Annaies de Chimie, t. xiii. p. 108 ; Annuaire, 1832, p. 216.) “We must conclude from these observations,” says Arago, “that the cometary light was not entirely composed of rays having the properties of direct light; there being light which was reflected specularly or polar- ized, that is, coming from the sun. It cannot be stated with absolute certainty, that comets shine only with borrowed light, for bodies, in becoming self-luminous, do not on that account lose the power of reflecting foreign light.” * Arago, in the Annuaire, 1832, pp. 217-220. Sir John Herschel, Astron., § 488. A ; 92 COSMOS. that it remains entirely within the limits of our planetary system, attaining its aphelion between the orbits of the smaller planets and that of Jupiter. Its eccentricity must be assumed at 0°845, that of Juno (which has the greatest eccentricity of any of the planets) being 0°255. Encke’s comet has several times, although with difficulty, been ob- served by the naked eye, asin Europe in 1819, and, according to Riimker, in New Holland in 1822. Its period of revolu- tion is about 38} years; but, from a careful comparison of the epochs of its return to its perihelion, the remarkable fact has oeen. discovered, that these periods have diminished in the most regular manner between the years 1786 and 1838, the diminution amounting in the course of 52 years to about 1,8, days. The attempt to bring into unison the results of observation and calculation in the investigation of all the planetary disturbances, with the view of explaining this phe- nomenon, has led to the adoption of the very probable hy-. pothesis, that there exists, dispersed in space, a vaporous substance capable of acting as a resisting medium. This matter diminishes the tangential force, and with it the major axis of the comet’s orbit. The value of the constant of the: resistance appears to be somewhat different before and after the perihelion; and this may, perhaps, be ascribed to the altered form of the small nebulous star in the vicinity of the Sun, and to the action of the unequal density of the strata of cosmical ether.* These facts, and the investigations to which they have led, belong to the most interesting results of modern astronomy. Encke’s comet has been the means of leading astronomers to a more exact investigation of Jupiter's mass (a most important point with reference to the ealcula- tion of perturbations); and, more recently, the course of this comet has obtained for us the first determination, al- though only an approximative one, of a smaller mass for Mercury. The discovery of Encke’s comet, which had a period o1 only 31 years, was speedily followed, in 1826, by that of another, Biela’s comet, whose period of revolution is 62 years, and which is likewise planetary, having its aphelion beyond the orbit: of. Jupiter but within that of Saturn. It * Encke, in the A stronomische Nachrichten, 1848, No. 489, s. 180-122 COMETS. 93 has a fainter light than Encke’s comet, ard, like the latter, its motion is direct, whilst Halley’s comet moves in a course opposite to that pursued by the planets. Biela’s comet presents the first certain example of the orbit of a comet intersecting that of the Earth. This position, with reference to our planet, may, therefore, be productive of dan- ger, if we can associate an idea of danger with so extraor- dinary a natural phenomenon, whose history presents no parallel, and the results of which we are consequently unable correctly to estimate. Small masses endowed with enor- mous velocity may certainly exercise a considerable power ; but Laplace has shown that the mass of the comet of 1770 is probably not equal to 3455 of that of the Earth, estimating further with apparent correctness, the,mean mass of comets as much below s5¢/555 that of the Earth, or about ;,4,, that of the Moon.* We must not confound the passage of Biela’s comet through the Earth’s orbit with its proximity to, or collision with, our globe. When this passage took place, on the 29th of October, 1832, it required a full month before the Karth would reach the point of intersection of the two orbits. These two comets of short periods of revolution, also inter- sect each other, and it has been justly observed,} that amid the many perturbations experienced by such smail bodies from the larger planets, there is a possibility—supposing a meeting of these comets to occur in October—that the inha- bitants of the Earth may witness the extraordinary spectacle of an encounter between two cosmical bodies, and possibly of their reciprocal penetration and amalgamation, or of their destruction by means of exhausting emanations. Events of this nature, resulting either from deflection occasioned by disturb- ing masses, or primevally intersecting orbits, must have been of frequent occurrence in the course of millions of years in * Laplace, Hapos. du Syst. du Monde, pp. 216, 237. + Littrow, Beschreibende Astron., 1835, s. 274. On the inner comet recently discovered by M. Faye, at the Observatory of Paris, and whose eccentricity is 0°551, its distance at its perihelion 1-690, and its distance at its aphelion 5°832, see Schumacher, Astron. Nachr., 1844, No. 495. Regarding the supposed identity of the comet of 1766 with the third comet of 1819, see Astr. Nachr., 1833, No. 239; and on the identity of the comet of 1743 and the fourth comet of 1819, see No. 237 of the ‘last-mentioned work, 94 COSMOS. the immeasurable regions of ethereal space; but they must be regarded as isolated gccurrences, exercising no more general or alterative effects on cosmical relations than the breaking forth or extinction of a volcano within the limited sphere of our Earth. A third interior comet, having likewise a short period of revolution, was discovered by Faye, on the 22nd of Novem- ber, 1843, at the Observatory at Paris. Its elliptic path, which approaches much more nearly to a circle than that of any other known comet, is included within the orbits of Mars and Saturn. This comet, therefore, which, according to Goldschmidt, passes beyond the orbit of Jupiter, is one of the few whose perihelia are beyond Mars. Its period of revolution is 72%, years, and it is not improbable that the form of its present orbit may be owing to its great approxi- mation to Jupiter at the close of the year 1839. If we consider the comets in their inclosed elliptic orbits as members of our solar system, and with respect to the length of their major axes, the amount of their eccentricity, and their periods of revolution, we shall probably find that the three planetary comets of Encke, Biela, and Faye, are most nearly approached in these respects, first, by the comet discovered in 1766 by Messier, and which is regarded by Clausen as identical with the third comet of 1819; and next, by the fourth comet of the last-mentioned year, discovered by Blaupain, but considered by Clausen as identical with that of the year 1743, and whose orbit appears, like that of Lexell’s comet, to have suffered great variations from the proximity and attraction of Jupiter. The two last-named comets would likewise seem to haye a period of revolution not exceeding five or six years, and their aphelia are in the vicinity of Jupiter’s orbit. Amongst the comets that have a period of revolution of from seventy to seventy-six years, the first in point of importance with respect to theoretical and physical astronomy is Halley’s comet, whose last appearance, in 1835, was much less brilliant than was to be expected from preced- ing ones; next we would notice Olbers’ comet, discovered on the 6th of March, 1815; and lastly, the comet discovered by Pons in the year 1812, and whose elliptic orbit has been determined by Encke. The two latter comets were invisible to the naked eye. We now know with certainty of nine —— = = COMETS. 95 returns of Halley's large comet, it having recently been proved by Laugier’s calculations,* that in the Chinese table of comets, first made known to us by Edward Biot, the comet of 1378 is identical with Halley’s; its periods of revolution have varied in the interval between 1378 and 1835 from 74:91 to 77°58 years, the mean being 76:1. A host of other comets may be contrasted with the cos- mical bodies of which we have spoken, requiring several thousand years to perform their orbits, which it is difficult to determine with any degree of certainty. The beautiful comet of 1811 requires, according to Argelander, a period of 3065 years for its revolution, and the colossal one of 1680 as much as 8800 years, according to Encke’s calculation. These bodies respectively recede, therefore, 21 and 44 times further than Uranus from the Sun, that is to say, 33,600 and 70,400 millions of miles. At this enormous distance the attractive force of the Sun is still manifested; but whilst the velocity of the comet of 1680 at its perihelion is 212 miles in a second, that is, thirteeen times greater than that of the Earth, it scarcely moves ten feet in the second when at its aphelion. This velocity is only three times greater than that of water in our most sluggish European rivers, and equal only to half that which I have observed in the Cassiquiare, a branch of the Orinoco. It is highly probable, that amongst the innu- merable host of uncalculated or undiscovered comets, there are many whose major axes greatly exceed that of the comet of 1680. In order to form some idea by numbers, I do not say of the sphere of attraction, but of the distance in space of a fixed star, or other sun, from the aphelion of the comet of 1680 (the furthest receding cosmical body with which we are acquainted in our solar system), it must be remembered that, according to the most recent determinations of parallaxes, the nearest fixed star is full 250 times further removed from our sun than the comet in its aphelion. The comet’s distance is only 44 times that of Uranus, whilst a Centauri is 11,000, and 61 Cygni 31,000 times that of Uranus, according to Bes- sel’s determinations. Having considered the greatest distances of comets from * Laugier, in the Comptes rendus des Séances de lA cadémis, 1843, t. xvi, p. 1006, 96 COSMOS. the central body, it now remains for us to notice instances the greatest proximity hitherto measured. Lexell and Burckhardt’s comet of 1770, so celebrated on account of the disturbances it experienced from Jupiter, has approached the Earth within a smaller distance than any other comet. On the 28th of June, 1770, its distance from the Earth was only six times that of the Moon. The same comet passed twice, viz. in 1769 and 1779, through the system of Jupiter’s four satellites without producing the slightest notable change in the well-known orbits of these bodies. The great comet of 1680 approached at its perihelion eight or nine times nearer to the surface of the Sun than Lexell’s comet did to that of our Earth; being on the 17th of December, a sixth part of the Sun’s diameter, or seven-tenths of the distance of the Moon, from that luminary. Perihelia occurring beyond the orbit of Mars can seldom be observed by the inhabitants of the Earth, owing to the faintness of the light of distant comets; and amongst those already calculated, the comet of 1729 is the cnly one which has its perihelion between the orbits of Pallas and Jupiter; it was even observed beyond the latter. . Since scientific knowledge, although frequently blended with vague and superficial views, has been more extensively diffused through wider circles of social life, apprehensions of the possible evils threatened by comets have acquired more weight, as their direction has become more definite. The certainty that there are within the known planetary orbits, comets which revisit our regions of space at short intervals— that great disturbances have been produced by Jupiter and Saturn in their orbits, by which such as were apparently harmless have been converted into dangerous bodies—the intersection of the Earth’s orbit by Biela’s comet—the cos- mical vapour, which acting as a resisting and impeding medium, tends to contract all orbits—the individual difference of comets, which would seem to indicate considerable decreas: ing gradations in the quantity of the mass of the nucleus—are all considerations more than equivalent both as to number and variety, to the vague fears entertained in early ages, of the general conflagration of the world by flaming swords, and stars with fiery streaming hair. As the consolatory considera- tions which may be derived from the calculus of probabilities, AEROLITES. 97 address themselves to reason and to meditative understanding only, and not to the imagination or to a desponding condition of mind, modern science has been accused, and not entirely without reason, of not attempting to allay apprehensions which it has been the very means of exciting. It is an inherent attribute of the human mind to experience fear, and not hope or joy, at the aspect of that which is unexpected and extraor- dinary.* The strange form of a large comet, its faint nebulous tight, and its sudden appearance in the vault of heaven, have in all regions been almost invariably regarded by the people at large as some new and formidable agent, inimical to the existing state of things. The sudden occurrence and short duration of the phenomenon lead to the belief of some equally rapid reflection of its agency in terrestrial matters; whose varied nature renders it easy to find events that may be re- garded as the fulfilment of the evil foretold by the appearance of these mysterious cosmical bodies. In our own day, how- ever, the public mind has taken another and more cheerful, although singular turn, with regard to comets; and in the German vineyards in the beautiful valleys of the Rhine and Moselle, a belief has arisen, ascribing to these once ill-omened bodies, a beneficial influence on the ripening of the vine. The evidence yielded by experience, of which there is no lack in these days, when comets may so frequently be observed, has not been able to shake the common belief in the meteorological ig of the existence of wandering stars, capable of radiating eat. From comets, I would pass to the consideration of a far more enigmatical class of agglomerated matter—the smallest of all asteroids, to which we apply the name aerolites, or meteoric stones,t when they reach our atmosphere in a frag- mentary condition. If I should seem to dwell on the specific * Fries, Vorlesungen iiber die Sternkunde, 1833, s. 262-267 (Lee- tures on the Science of Astronomy.) An infelicitously chosen instance of the good omen of a comet. may be found in Seneca, Nat. Quest., ¥iis 17 and 21. The philosopher thus writes of the comet : “ Quem nos Ne- ronis principatu letissimo vidimus et qui cometis detraxit infamiam.” + (Much valuable information may be obtained regarding the origin and. composition of aerolites or meteoric stones in Memoirs on the sub- ject, by Baumbeer and other writers, in the nambers of Poggenderfé Annalen, from 1845 to the present time,|—7r. H 88 soento8.* enumeration of these bodies, and of comets, longer than “the general nature of this work might warrant, 'l have: not done so undesignedly. ‘The diversity existing in the individual eharacteristics of comets has already been noticed. The im- perfect knowledge we possess of their physical character, fenders it difficult im a work like the present, to give the proper degree of circumstantiality to the phenomena, which, although of frequent recurrence, have been observed with such Various degrees of accuracy, or to separate the necessary from , the accidental. It is only with respect to measurements and computations that the astronomy of comets has made any. marked advancement, and consequently a scientific considera-- tion of these bodies must be limited ‘to a specification of ‘the differences of physiognomy and conformation in the nucleus and tail, the instances of great approximation to other cos- mical bodies, and of the extremes in the length of their or- bits and in their periods of revolution. A faithful delineation ef these phenomena, ‘as well as of those which we proceed to consider, can only be given by sketchimg imdividual features: with the animated circumstantiality of reality. Shooting stars, fire balls, and meteoric stones are, with great probability, regarded as small bodies moving with planet. ary velocity, and revolving in obedience to the laws of: gravity in conic sections round the Sun. When these masses meet the Earth in their course, ‘and are attracted y, it, they enter within the limits of our atmosphere in a condition, and frequently let fall more or less sinnall heated stony fragments, covered with a shining black crust. When we enter into-a careful investigation of the facts observed at those epochs when showers of shooting stars fell periodically in Cumana in 1799, and in North America during the years 1838 and 1834, we shall find that fire balls cannot be con- sidered separately from shooting stars. Both these phenomena are frequently not only simultaneous and blended together, but they likewise are often found to merge into one another, ‘the’ ene phenomenon gradually assuming the character of the other alike with respect to the size of their discs, the emanation of sparks, and the velocities of their motion. Although explod- ing smoking luminous fire balls are sometimes seen even in the: brightness of tropical daylight,* equalling in size the apparent. * A friend of mine, much accustomed to exact trigonometrical mea surements, was in the year 1788 at Popayan, a city-which is 2° 26’ N. L, AEROLITES. 99° diameter of the Moon, innumerable quantities of shooting ' stars have, on the other hand, been observed to fall in forms’ of such extremely small dimensions, that they appear only as moving points, or phosphorescent lines.* © | -Tt still remains undetermined whether the many luminous bodies that shoot across the sky may not vary in their nature. On my return from the equinoctial zones, I was impressed with an idea that in the torrid regions of the tropics I had more frequently than in our colder latitudes seen shooting lying at an elevation of 5583 feet above the level of the sea, and at noon, when the sun was shining brightly in a cloudless sky, saw his room lighted up by a fire ball. He had his back to the window at the time, and on turning round, perceived that great part of the path traversed by _ the fire ball was still iluminated by the brightest radiance, Different nations have had the most various terms to express these phenomena, the Germans use the word Sternschnuppe, literally star snuff—an expression well suited to the physical views of the vulgar in former times, according to which, the lights in the firmament were said to . undergo a process of snuffing or cleaning,—and other nations generally adopt a term expressive of a shot or fall of stars, as the Swedish stjernj- fali—the Italian stella cadente, and the English star-shoot. In the woody district of the Orinoco, on the dreary banks of the Cassiquiare, I heard the natives in the Mission of Vasiva use terms still more inelegant than the German star snuff. (Relation Historique du Voy. aux Régione équinoa., t. ii. p. 513). These same tribes term the pearly drops of dew which cover the beautiful leaves of the heliconia, star-spit. In the Lithuanian mythology the imagination of the people has embodied its ideas of the nature and signification of falling stars under nobler and. more graceful symbols. The Parce, Werpeja, weave in heaven for the new-born child its thread of fate, attaching each separate thread to astar. When death approaches the person, the thread is rent, and the. star wanes and sinks to the earth. Jacob Grimm, Deutsche Mythologie, 1843, s, 685. * According to the testimony of Professor Denison Olmsted, of Yale College, New Haven, Connecticut. (See Poggend. Annalen der Physik, bd. xxx.s. 194.) Kepler, who excluded fire balls and - shooting stars from the domain of astronomy, because they were, according to his. views, “ meteors arising from the exhalations of the earth, and blending with the higher ether,” expresses himself, however, generally with much caution. He says: “Stelle cadentes sunt materia viscida inflammata. Larum alique inter cadendum absumuntur, alique vere in terram , pondere suo tracte. Necest dissimile vero, gquasdam conglo- batas esse ex materia faculentd, in ipsam auram etheream immiata : exque. attheris regione, tractu rectilineo, per aérem trajicere, ceu minutos cometas, occultd causa motus utrorumque,” Kepler, £pit.. Astron. Copernicane, t. i. p. 80. : H 2 ~_ i100 ‘COSMOS, stars fall as if from a height of twelve or fifteen thousand feet,. that they were of brighter colours and left a more brilliant line of light in their track, but this impression was no doubt owing to the greater transparency of the tropical atmo- sphere,* which enables the eye to penetrate further into dis- * Relation Historique, t. i. pp. 80,218, 527. If in falling stars, as in comets, we distinguish between the head or nucleus and the tail, we shall find that the greater transparency of the atmosphere in tropical climates is evinced in the greater length and brilliancy of the tail which may be observed in those latitudes. The phenomenon is therefore not necessarily more frequent there, because it is oftener seen and continues longer visible. The influence exercised on shooting stars by the character of the atmosphere is shewn occasionally even in our temperate zone, and at very small distances apart. Wartmann relates that on the occasion of a — November phenomenon at two places lying very near each other, Geneva. and Aux Planchettes, the number of the meteors counted were as 1 to 7, (Wartmann, Mém. sur les Etoiles filantes,p. 17.) The tail of a shooting star (or its train), on the subject of which Brandes has made so many exact and delicate observations, is in no way to be ascribed to the continuance of the impression produced by light on the retina. It sometimes continues visible a whole minute, and in some rare instances longer than the light of the nucleus of the shooting star; in which case the luminous track remains motionless. (Gilb. Ann., bd. xiv.s. 251.) This circumstance further indicates the analogy between large shooting stars and fire balls. Admiral Krusenstern saw, in his voyage round the world, the train of a fire ball shine for an hour after the luminous body itself had disappeared. and scarcely move throughout the whole time. (Reise, th.i. s. 58.) Sir Alexander Burnes gives a charming description of the transparency of the clear atmosphere of Bokhara, which was once so favourable to the pursuit of astronomical observations. Bokhara is situated in 39° 43’ N. L., and at an elevation of 1280 feet above the level of the sea, “ There isa constant serenity in its atmosphere, and an admirable clearness in thesky, At night, the stars have uncommon lustre, and the milky way shines glo- riously in the firmament. There is also a never-ceasing display of the most brilliant meteors, which dart like rockets in the sky: ten or twelve of them are sometimes seen in an hour, assuming every colour; fiery red, blue, pale and faint. It isamnoble country for astronomical seience, and great must have been the advantage enjoyed by the famed observatory of Samarkand.” (Burnes, Z'ravels into Bokhara, vol. ii. (1834,) p. 158.) A mere traveller must not be reproached for calling ten or twelve shooting stars in an hour, “ many,” since it is only recently that we have learnt, from careful observations on this subject in Europe, that eight is the mean number which may be seen in an hour in the field of vision of one individual (Quetelet, Corresp. Mathém., Novem. 1837, p. 447); this number is, however, limited to five or six by that diligent observer, @ibers. (Schum. Jahrb., 1838, 8, 325.) AEROLITES. “101 tanee. Sir Alexander Burnes likewise extols as a conse- quence of the purity of the atmosphere in Bokhara, the enchanting and constantly recurring spectacle of yariously- coloured shooting stars. The connection of meteoric stones with the grander phe- nomenon of fire balls—the former being known to be projected from the latter with such force as to penetrate from ten to fifteen feet into the earth—has been proved, among many ether instances, in the falls of aerolites at Barbotan, in the Department des Landes (24th July, 1790), at Siena (16th _June, 1794), at Weston, in Connecticut, U. S. (14th Decem- ber, 1807), and at Juvenas, in the Department of Ardéche (15th June, 1821). Meteoric stones are in some instances thrown from dark clouds suddenly formed in a clear sky, and fall with a noise resembling thunder. Whole districts have - thus occasionally been covered with thousands of fragmentary masses, of uniform character but unequal magnitudes, that have been hurled from one of these moving clouds. In less frequent cases, as in that which occurred on the 16th of September, 1843, at Kleinwenden, near Mihlhausen, a large _aérolite fell with a thundering crash, while the sky was clear and cloudless. The intimate affinity between fire balls and shooting stars is further proved by the fact that fire balls, from which meteoric stones have been thrown, have occa- _ sionally been found, as at Angers, on the 9th of June, 1822, having a diameter scarcely equal to that of the small fire- works, called Roman candles. The formative power, and the nature of the physical and chemical processes involved in these phenomena are questions - all equally shrouded in mystery, and we are as yet ignorant, ‘whether the particles composing the dense mass of meteoric stones are originally, as in comets, separated from one another in the form of vapour, and only condensed within the fiery ball when they become luminous to our sight, or whether in - the case of smaller shooting stars any compact substance actually falls, or, finally, whether a meteor is composed only _ of a smoke-like dust, containing iron and nickel; whilst we are wholly ignorant of what takes place within the dark cloud - from which a noise like thunder is often heard for many minutes before the stones fall.* * On meteoric dust, see Arago, in the Annuaire for 1832, p. 254. I ‘have very recently endeavoured to show, in another work, (Asie Cen: {102 . -COSMOS,: - We can ascertain by measurement the enormous, wonderful, ‘and wholly planetary velocity of shooting stars, fire balls, and meteoric stones, and we can gain a knowledge of what is the _ general and uniform character of the phenomenon, but not of the genetically cosmical process and the results of the metamorphoses. If meteorie stones while revolving in space are already consolidated into dense masses,* less. dense, how- trale, t. i. p. 408,) how the Scythian saga of the sacred gold, which fell ‘burning from heaven, and.-remained in the possession of the Golden Horde of the Paralatze, (Herod., iv. 5-7,) probably originated inthe vague _recollection of the fall of anaerolite. The ancients had also some strange fictions (Dio Cassius, Ixxv. 1259,) of silver which had fallen from heaven, and with which it had been attempted, under the Emperor Se- -verus, to cover bronze coins; metallic iron was, however, known to exist ‘in meteoric stones. (Plin. ii, 56.) The frequently-recurring expression -lapidibus pluit, must not always be understood to refer to falls of aerolites. In Livy. xxv. 7, it probably refers to pumice (rapilli) ejected from “the volcano, Mount Albanus (Monte Cavo), which was not wholly . extinguished at the time. (See Heyne, Opuscula Acad., t. iii. p. 261; and my Relation Hist., t.i. p. 394.) The contest of Hercules with the Ligyans, on the road from the Caucasus to the Hesperides, belongs to a different sphere of ideas, being an attempt to explain mythically the origin of the round quartz blocks in the Ligyan field of stones at the mouth of the Rhone, which Aristotle supposes to have been ejected from ‘a fissure during an earthquake, and Posidonius, to have been caused ~ by the force of the waves of an inland piece of water In the fragments . that we still possess of the play of Aischylus, the Prometheus Delivered, everything proceeds, however, in part of the narration, as in a fall of aerolites, for Jupiter draws together a cloud and causes the “ district ‘around: to be covered by a shower of round stones.” Posidonius even ~ ventured to deride the geognostic myth of the blocks and stones. The “ Ligyan field of stones was, however, very naturally and well described - by the ancients. The district is now known as La Crau. (See Guerin, . Mesures Burométriques dans les Alpes, et Météorologie d’ Avignon, _ 1829, chap. xii. p. 115.) i * The specific weight of aerolites varies from 1°9 (Alais) to 4°3 (Tabor). Their general density may be set down as 8, water being 1. As to ‘what has been said in the text of the actual diameters of fire balls, we ~ must remark that the numbers have been taken from the few measuree '*\ ments that can be relied upon as correct. These give for thefire ball of - Weston, Connecticut, (14th December, 1807,) only 500, for that, observed \ by Le Roi, (10th July, 1771,) abont 1000, and for that estimated by Sir Charles Blagden, (18th January, 1783,) 2600 feetin diameter. Brandes -(Uniterhaltungen, bd. i.'s. 42) ascribes a diameter varying from 80 to 120 feet to shooting stars, and a luminous train extending from 12’to 416:miles. There are, however, ample optical causes for supposing that .cthe apparent diameter of fire. balls and shooting stars has been, very APROLITES. 108 ever, than the mean density of the Earth, they must be very ‘small nuclei, which, surrounded by inflammable vapour or gas, form the innermost, part of fire balls, from the height and apparent diameter of which we may in the case of the largest, estimate that the actual diameter varies from 500 - - to about 2800 feet. The largest. meteoric masses as yet known, are those of Otumpa, in Chaco, and of Bahia, in Brazil, described by Rubi de Celis as being from 7 to 74 feet in length. The meteoric stone of gos: Potamos, cele- brated in antiquity, and even mentioned in the Chronicle of the Parian Marbles, which fell about the year in which Socrates was born, has been described as of the size of two millstones, and equal in weight to a full waggon load. Notwithstanding the failure that has. attended the efforts. of the African traveller, Brown, I do. not. wholly. relinguish the hope that, even after a lapse of 2312 years,. this. Thracian meteoric mass, which it would be so difficult to destroy, may much overrated. The volume of the largest fire ball yet observed cannot be compared with that of Ceres, estimating this planet to have a diameter of only 70 English miles, (See the generally so exact and admirable . treatise, On the Connexion of the Physical Sciences, 1835, p. 411.) With the view of elucidating what has been stated in the text regarding the large aerolite that fell into the bed of the river Narni, but has not again been found, I will give the passage made known by Pertz, from: the Chronicon Benedicti, Monachi- Sancti Andrew in. Monte Soracte, a MS, belonging to the tenth century, and preserved.in the Chigi Li- brary at Rome. The barbarous Latin. of that age has been left un- changed. “ Anno 921, temporibus domini Johannis Decimi pape, in anno pontificatus illius 7 visa sunt signa. Nam juata urbem Romam lapides plurimi de celo cadere visi sunt. In. civitate que vocatur Narnia tam divi actetri, ut nihil aliud. eredatur, quam de infernalibus locis deducti essent.. Nam ita ex illis lapidibus unus omnium maximus ‘est, ut decidens in fumen Narnus, ad mensuram unius cubiti super aquas fluminis usque liodie videretur. Nam et ignite facule de celo plurime omnibus in hac civitate Romani populi vise sunt, ita ut pene terra contingeret. Alice cadentes,” &e. (Pertz, Monum. Germ. Hist. Scripitores, t. iii, p.715.) On the aerolites of gos Potamos, which. fell, according to the Parian Chronicle, in the 78 1 Olympiad, see Béckh; Corp. Insc. Graec., t. ii. pp. 302, 320, 340; also, Aristot. Metcor:, ii 7; ‘(Ideler’s Comm., t. i. pp. 404-407): Stob. Ecl. Phys., i. 25, p. 508) (Heeren): Plut. Lys.,c:12; Diog. Laert., ii. 10; and see alsosubsequent notes in this work, According to a Mongolian tradition, a black frags ment of a rock, forty feet in height, fell from heaven on a plain near the sures of the Great Yellow River in Western China. (Abel Rémusat, im erie, Jour, de Phys.; 1819, Mai; pv 264:): ay 104 COSMOS. be found, since the region in which it fell is now become so easy of access to European travellers. The huge aerolite which in the beginning of the tenth century fell into the river at Narni, projected between three and four feet above the sur- face of the water, as we learn from a document lately dis- covered by Pertz. It must be remarked that these meteoric bodies, whether in ancient or modern times, can only be re- garded as the principal fragments of masses that have been Nag up by the ‘explosion either of a fire ball or a dark cloud. On considering the enormous velocity with which, as has been mathematically proved, meteoric stones reach the earth from the extremest confines of the atmosphere, and the lengthened course traversed by fire balls through the denser strata of the air, it seems more than improbable that these metalliferous stony masses, containing perfectly-formed crys- tals of olivine, labradorite, and pyroxene, should in so short a period of time have been converted from a vaporous con- dition to a solid nucleus. Moreover, that which falls from meteoric masses, even where the internal composition is chemically different, exhibits almost always the peculiar cha- racter of a fragment, being of a prismatic or truncated pyra- midal form, with broad somewhat curved faces, and rounded angles. But whence comes this form, which was first recog- nised by Schreiber, as characteristic of the severed part of a rotating planetary body? Here, as in the sphere of organic life, all that appertains to the history of development remains hidden in obscurity, Meteoric masses become luminous and kindle at heights which must be regarded as almost devoid of air, or occupied by an atmosphere that does not even contain zo0s00 part of oxygen, The recent investigations of Biot, on the important phenomenon of twilight,* have considerably _ * Biot, Traité d’Astronomie physique (3eme éd.), 1841, t. i. pp. 149, 177, 238, 312. My lamented friend Poisson endeavoured, in a singular manner, to solve the difficulty attending an assumption of the spon- taneous ignition of meteoric stones at an elevation where the density of the atmosphere is almost null. These are his words: “ It is difficult to attribute, as is usually done, the incandescence of aerolites to friction against the molecules of the atmosphere, at an elevation above the earth where the density of the air is almost null. May we not suppose that the clectric fluid, in a neutral condition, forms a kind of atmosphere, extending far beyond the mass of our atmosphere, yet subject to ter- AEROLITES. 105 lowered the lines which had, perhaps with some degree of temerity, been usually termed the boundaries of the atmo- sphere ; but processes of light may be evolved independently of the presence of oxygen, and Poisson conjectured that aerolites were ignited far beyond the range of our atmosphere. Numerical calculation, and geometrical measurement, are the only means by which, as in the case of the larger bodies of our solar system, we are enabled to impart a firm and safe basis to our investigations of meteoric stones. Although Halley pronounced the great fire ball of 1686, whose motion was opposite to that of the Earth in its orbit,* to be a cosmical body; Chladni, in 1794, first recognised, with ready acuteness of mind, the connection between fire balls and the stones projected from the atmosphere, and the motions of the former bodies in space.t A brilliant confirmation of the cosmical origin of these phenomena has been afforded by Denison Olmsted, at Newhaven, Connecticut, who has shown, on the concurrent authority of all eye-witnesses, that during the celebrated fall of shooting stars, on the night between the 12th and 13th of November, 1833, the fire balls and shooting stars all emerged from one and the same quarter of the heavens, namely, in the vicinity of the star y in the con- stellation Leo, and did not deviate from this point, although the star changed its apparent height and azimuth during the time of the observation. Such an independence of the Earth’s rotation shows that the luminous body must have reached our restrial attraction, although physically imponderable, and consequently following our globe in its motion? According to this hypothesis, the bodies of which we have been speaking would, on entering this impon- derable atmosphere, decompose the neutral fluid by their unequal action on the two electricities, and they would thus be heated, and in a state ofincandescence, by becoming electrified.” (Poisson, Rech. sur la Proba- bilité des Jugements, 1837, p. 6.) * Philos. Transact., vol. xxix. pp. 161-163. + The first edition of Chladni’s importanttreatise, Veber den Ursprung der von Pallas gefundenen und anderen Eisenmassen (On the Origin ef the masses of Iron found by Pallas, and other similar masses), appeared two months prior to the shower of stones at Siena, and two years before Lichtenberg stated, in the Géttingen Taschenbuch, that “ stones reach our atmosphere from the remoter regions of space.” Comp. also Olbers? letter to Benzenberg, 18th Noy, 1827 in Benzenberg’s J'reatise on Shooting Stars, p, 186, 106 _» COSMOS. . atmosphere from without. According to Encke’s: computa. tion* of the whole number of the observations made in the United States of North America, between 35° and 42° lat., it would appear that all these meteors came from the same point of space in the direction in which the earth was moving at the time. On the recurrence of falls of shooting stars in North America, in the month of November of the years 1834 and 1837, and in the analogous falls observed at Bremen, in 1838, a like general parallelism of the orbits, and the same direction of the meteors from the constellation Leo, weré again noticed. It has been supposed that a greater paral- lelism was observable in the direction of periodic falls of * Encke, in Poggend. Annalen, bd. xxxiii. (1834), s. 213. Arago; in the Annuaire for 1836, p. 291. Two letters which I wrete to Benzenberg, May 19 and October 22, 1837, on the conjectural pre: cession of the nodes in the orbit of periodical falls. of shooting stars., (Benzenberg’s Sternsch.,.s. 207 und 209.) Olbers subsequently adopted this opinion of the gradual retardation of the November phenomenon, (Astron. Nachr., 1838, No. 372, s. 180.) If I may venture to combine iwo of the falls of shooting stars mentioned by the Arabian writers with the epochs found by: Boguslawski for the fourteenth century, I obtain the following more or less accordant elements of the movements of the, nodes :— In Oct., 902, on the night in which King Ibrahim ben Ahmed died, there fell a heavy shower of shooting stars, “like a fiery rain ;” and this year was, therefore, called the year of stars. ee Hist. de la Domin. de los Arabes, p. 346.) On the 19th of Qct., 1202, the stars were in motion all fights, «They fell like locusts. » (Comptes Rendus, 1837, t. i. p. 294; and Frehn, in the Bull. de 1 Académie de St. Petersbourg, t. iii. p. 308.) On the 21st Oct., O.S., 13866, “die sequente post festum XI. milli Virginum ab hora matutina usque ad horam primam vise sunt quast stelle de celo. cadere continuo, et in tanta multitudine, quod nema nerrare sufficit.” This remarkable notice, of which we shall speak more fully in the subsequent part of this work, was found by the younger Von Boguslawski, in Benesse (de Horowic) de Weitmil or Weithmiil; Chronicon Ecclesie Pragensis, p. 389; This chronicle may also be found in the second part.of Scriptores. rerum Bohemicarum, by Pelzel and Dobrowsky, 1784. (Schum. Asér. Nachr., Dec. 1839.) ~ On the night between the 9thand 10th of November, 1787, many falling stars were observed at Manheim, Southern Germany, by: Hemmer. (Kiimtz, Meteor., th. iii. s, 237.) After midnight, on the 12th of November, 1799, occurred the extra> ordinary fall of stars at Cumana, which Bonpland and myself have described, and which was observed over a. ae on of the oo Relat. Hist., t. i, pp. 519-527.) . AEROLITEs. 107 -shooting stars, than in those of sporadic occurrence; and it has further been remarked, that in the periodically-recurring . falls in the month of August, as, for instance, in the year 1839, -the meteors came principally from one point between Perseus and Taurus, towards the latter of which constellations the Earth was then moving. This peculiarity of the phenomenon, manifested in the retrograde direction of the orbits in No- vember and August, should be thoroughly investigated by -aceurate observations, in order that it may either be fully confirmed or refuted. _- The heights of shooting stars, that is to say, the heights ‘of the poimts at which they begin and cease to be visible, vary exceedingly, fluctuating between 16 and 140 miles. This important result, and the enormous velocity of these problematical asteroids, were first ascertained by Benzenberg ‘and Brandes, by simultaneous observations and determina- tions of parallax at the extremities of a base line of 49,020 feet in length.* The relative velocity of motion is from 18 to 36 miles in a second, and consequently equal to planetary Between the 12th and 13th of November, 1822, shooting stars, inter- mingled with fire balls, were seen in large numbers by Kloden, at Potsdam. (Gilbert's Ann., bd. Ixxii. s. 291.) On the 13th of November, 1831, at 4 o’clock in the morning, a great shower of falling stars was seen by Captain Bérard, on the Spanish coast, near Carthagena del Levante. (Annuaire, 1836, p. 297.) In the night between the 12th and 13th of November, 1833, oceurred the phenomenon so admirably described by Professor Olmsted, in North America, : In the night of the 13-14th of November, 1834, a similar fall of ‘shooting stars was seen in North America, although the numbers. were not quite so considerable. (Poggend. Annalen, bd. xxxiv. s. 129.) On the 13th of November, 1835, a barn was set on fire by the fall of a sporadic fire ball, at Belley, in the Department de Ain. (An- nusmire, 1836, p. 296.) In the year 1838, the stream showed itself most decidedly on the night of the 13-14th of November. (Astron. Nachr., 1838, No. 372.) I am well aware that, amongst the 62 shooting stars simultane- ously observed in. Silesia, in 1823, at the suggestion of Professor Brandes, some appeared to have an elevation of 183 to 240, or even -400 miles. (Brandes, Unterhaltungen fiir Freunde der Astronomie und Physik, heft i. s. 48. Instructive Narratives for the Lovers of Astronomy and Physics.) But Olbers considered that all determina- tions for elevations beyond 120 miles must be doubtful, owing to: the ‘gmallness of the parallax, - O A 108 _ Cosmos. velocity. This planetary velocity*, as well as the direction of the orbits of fire balls and shooting stars, which has fre- quently been observed to be opposite to that of the Earth, may be considered as conclusive arguments against the hypo- thesis that aerolites derive their origin from the so-called active lunar volcanoes. Numerical views regarding a greater or lesser volcanic force on a small cosmical body, not sur- rounded by any atmosphere, must from their nature be wholly arbitrary. We may imagine the reaction of the interior of a planet on its crust ten or even a hundred times greater than that of our present terrestrial volcanoes; the direction of masses projected from a satellite revolving from west to east might appear retrogressive, owing to the Earth in its orbit subsequently reaching that point of space at which these bodies fall. If we examine the whole sphere of relations which I have touched upon in this work, in order to esca the charge of having made unproved assertions, we shall find that the hypothesis of the selenic origin of meteoric stones} * The planetary velocity of translation, the movement in the orbit, is in Mercury 26°4, in Venus 19°2, and in the Earth 16:4 miles ina second. + Chladni states, that an Italian physicist, Paolo Maria Terzago, on the occasion of the fall of an aerolite at Milan, in 1660, by which a Franciscan monk was killed, was the first who surmised that aerolites were of selenic origin. He says, in a memoir entitled Museum Sep- talianum, Manfredi Septale, Patricii Mediolanensis, industrioso la- bore constructum (Tortona, 1664, p.44), “ Labant philosophorum mentes sub horum lapidum ponderibus ; ni dicere velimus, lunam terram alieram, sine mundum esse, ex cujus montibus divisa frustra in infe- wtorem nostrum hunc orbem delabantur.” Without any previous know- ledge of this conjecture, Olbers was led, in the year 1795 (after the celebrated fall at Siena, on the 16th of June, 1794), into an investi- ‘gation of the amount of the initial tangential force that would be requisite to bring to the Earth masses projected from the Moon. This ‘ballistic problem occupied, during ten or twelve years, the attention of the geometricians Laplace, Biot, Brandes, and Poisson. The opinion which was then so prevalent, but which has since been aban- “doned, of the existence of active volcanoes in the Moon, where air and. water are absent, led to a confusion in the minds of the generality of persons between mathematical possibilities and physical probabilities. Olbers, Brandes, and Chladni thought “ that the velocity of 16 to 32 miles with which fire balls and shooting stars entered our atmosphere,” furnished a refutation to the view of their selenic origin. According to Olbers, it would require to reach the Earth, setting aside the re- AEROLITES, 109. depends upon a number of conditions whose accidental coin- cidence could alone convert a possible into an actual fact. The view of the original existence of small planetary masses in space is simpler, and at the same time more analogous with those entertained concerning the formation of other portions of the solar system, sistance of the air, an initial velocity of 8292 feet in the second; ae- cording to Laplace, 7862; to Biot, 8282; and to Poisson, 7595, Laplace states that this velocity is only five or six times as great as that of a cannon-ball, but Olbers has shewn, “ that with such an initial velocity as 7500 or 8000 feet in a second, meteorie stones would arrive at the surface of our earth with a velocity of only 35,000 feet, (or 1°53 German geographical mile.) But the measured velocity of meteoric stones averages 5 such miles, or upwards of 114,000 feet to a second ; and consequently the original velocity of projection from the Moon must be almost 110,000 feet, and therefore 14 times greater than Laplace asserted.” (Olbers, in Schum. Jahrb., 1837, pp. 52-58 ; and in Gehler, Nues physik. Wérterbuche, bd. vi. abth. 3, s. 2129-2136.) If we could assume volcanic forces to be still active on the Moon’s surface, the absence of atmospheric resistance would certainly give to their projectile force an advantage over that of our terrestrial volcanoes ; but. even in respect to the measure of the latter force (the projectile force of our own volcanoes), we have no observations on which any reliance ean be placed, and it has probably been exceedingly over-rated. Dr. Peters, who accurately observed and measured the phenomena presented by &tna, found that the greatest velocity of any of the stones projected from the crater was only 1250 feet to a second. Observations on the Peak of Teneriffe, in 1798, gave 3000 feet. Although Laplace, at the end of his work (Hxpos. du Syst. du Monde, ed. de 1824, p. 399), cautiously observes, regarding aerolites, “ that in all probability they come from the depths of space ;” yet we see from another passage (chap. vi. p. 233), that, being probably unacquainted with the extraordinary planetary velocity of meteoric stones, he inclines to the hypothesis of their lunar origin, always, however, assuming that the stones projected from the Moon “ become satellites of our Earth, describing around it more or less eccentric orbits, and thus not reaching its atmosphere until several or even many revolutions have been accomplished.” As an Italian at Tortona had the fancy that aerolites came from the Moon, so some of the Greek philosophers thought they came from the Sun. This was the opinion of Diogenes Laertius (ii. 9), regarding the origin of the mass that fell at Aigos Potamos (see note, p. 103). Pliny, whose labours in recording the opinions and statements of preceding writers are astonishing, repeats the theory, and derides it the more freely, because he, with earlier writers (Diog. Laert., 3 and 5, p. 99, Hiibner), accuses Anaxagoras of having predicted the fall of aerolites from the Sun: * Celebrant Greeci Anaxagoram Clazomenium Olympiadis septuagesima octavee secundo anno preedixisse celestium litterarum scientia, quibus diebus saxum casurum esse e sole, idque factum interdiu in Thracios 110 COSMOS. “It is very probable that a large number of these cosmical bodies traverse space undestroyed by the vicinity of our atmosphere, and revolve round the Sun without experiencing any alteration but a slight increase in the eccentricity of their orbits, occasioned by the attraction of the Earth's mass. We may, consequently, suppose the possibility of these bodies. remaining invisible to us during many years and frequent revolutions. The supposed phenomenon of ascending shooting stars and fire balls, which Chladni has unsuccessfully endea- voured to explain on the hypothesis of the reflection of strongly parte ad Aigos flumen. Quod si quis preedictum credat, simul fateatur’ mecesse est, majoris miraculi divinitatem Amnaxagore fuisse, solvique rerum nature intellectum, et confundi omnia, si aut ipse Sol lapis esse aut unquam lapidem in eo fuisse credatur; decidere tamen crebro non erit dubium.” The fall ofa moderate-sized stone, which is preserved in the: Gymnasium at Abydos, is also reported to have been foretold by Anax- agoras. The fall of aerolites in bright sunshine, and when the Moon’s disc was invisible, probably led to the idea of sun-stones. Moreover, according to one of the physical dogmas of Anaxagoras, which brought on him the persecution of the theologians (even as they have attacked the geologists of our own times), the Sun was regarded as*“ a molten fiery mass” (uidpoc dvdzvpoc.) In accordance with these views of Anax- agoras, we find Euripides, in Phaéton, terming the Sun “ a golden mass ;” that is to say, a fire-coloured, brightly-shining matter, but not leading to the inference that aerolites are golden sun-stones. (See note to page 101.) Compare Valckenaer, Diatribe in Eurip. perd. Dram. Reliquias, 1767, p. 30. Diog. Laert., ii. 40. Hence, among the Greek philosophers, we find four hypotheses regarding the origin of falling stars: a telluric origin from ascending exhalations ; masses of stone raised by hurricane (see Aristot., Meteor., lib. i. cap. iv. 2--13, and cap. vii. 9); a solar origin; and lastiy, an origin in the regions of space, as heavenly bodies which had long remained invisible. Re: specting this last opinion, which is that of Diogenes of Apollonia, and entirely accords with that of the present day, see pages 112 and 113. It is worthy of remark, that in Syria, as I have been assured by a learned orientalist, now resident at Smyrna, Andrea de Nericat, who instructed me in Persian, there is a popular belief that aerolites chiefly fall on élear moonlight nights. The ancients, on the contrary, especially looked for their fall during lunar eclipses. (See Pliny, xxxvii. 10, p. 164. Solinus, c. 37. Salm., Hwerc., p. 531; and the passages collected by Ukert, in his Geogr. der Griechen und Romer, th. ii. 1. 8. 131, note 14.) On the improbability that meteoric masses are formed from metal-dis- solving gases, which, according to Fusinieri, may exist in the highest strata of our atmosphere, and, previously diffused through an almost boundless space, may suddenly assume a solid condition, and on the penetration and misceability of gases, see my Relat. Hist., t. i. p. 526." AEROLITES. tit eompressed ai, appears at first sight as the cottsequence of" gome unknown tangential force, propelling bodies from the earth; but Bessel has shown by theoretical deductions, con- firmed by Feldt’s carefully conducted calculations, that owing to the absence of any proofs of the simultaneous occurrence of the observed disappearances, the assumption of an ascent of shooting stars was rendered wholly improbable, and inad- missible as a result of observation.* The opinion advanced by Olbers that the explosion of shooting stars and ignited fire balls not moving in straight lines may impel meteors upwards in the manner of rockets, and influence the direction of their orbits, must be made the subject of future researches. ' Shooting stars fall either separately and in inconsiderable numbers, that is, sporadically, or in swarms of many thousands. The latter, which are compared by Arabian authors to swarms of locusts, are periodic in their occurrence, and move in streams, generally im a parallel direction. Amongst periodic falls, the most celebrated are that known as the November phenomenon, occurring from about the 12th to the 14th of November, and that of the festival of St. Lawrence (the 10th of August), whose “‘ fiery tears” were noticed in former times in a church calendar of England, no less than in old tra- ditionary legends, as a meteorological event of constant re- eurrence.t| Notwithstanding the great quantity of shooting '* Bessel, in Schum. Astr. Nachr., 1839, Nr. 380 und 881, s. 222 und 346. At the conclusion of the Memoir there is a comparison of the Sun’s longitudes with the epochs of the November phenomenon, from the period of the first observations in Cumana in 1799. + Dr. Thomas Forster (The Pocket Encyclopedia of Natural Phe-. nomena, 1827, p. 17) states that a manuscript is preserved in the library of Christ's College, Cambridge,* written in the tenth century by a monk, and entitled Hphemerides Rerum Naturalium, in which the natural phenomena for each day of the year are inscribed, as for instance, the first flowering of plants, the arrival of birds, &e.; the 10th of August is distinguished by the word “meteorodes.” It was this indication and the tradition of the fiery tears of St. Lawrence that chiefly induced Dr. Forster to undertake his extremely zealous investigation of the August phenomena. (Quetelet, Correspond. Mathém., Série III. t. i. 1837, p. 433.) * {No such manuscript is at present known to exist in the Library of that College. For this information Iam indebted to the inquiries of Mr. Cory of Pembroke College, the learned editor of Hieroglyphics of Horapotlo Nilous, Greek and English, 1840,.]-—7%r. 112 COSMOS, stars and fire balls of the most various dimensions, which, according to Kléden, were seen to fall at Potsdam, on the night between the 12th and 13th of November, 1822, and on the same night of the year in 1832, throughout the whole of Europe, from Portsmouth to Orenburg on the Ural River, and even in the Southern Hemisphere, as in the Isle of France, no. attention was directed to the pertodicity of the phenomenon, and no idea seems to have been entertained of the connection existing between the fall of shooting stars and the recurrence of certain days, until the prodigious swarm of shooting stars which occurred in North America between the 12th and 13th of November, 1833, and was observed by Olmsted and Palmer. The stars fell, on this occasion, like flakes of snow, and it was calculated that at least 240,000 had fallen during a period of nine hours. Palmer of New Haven, Connecticut, was led, in consequence of this splendid phenomenon, to the recollection, of the fall of meteoric stones in 1799, first described by Ellicot and myself.* and which, by a comparison of ‘the facts I had adduced, showed that the phenomenon had been simultaneously seen in the New Continent, from the equator to New Herrn- hut in Greenland, (64° 14’ lat.) and between 46° and 82° long. The identity of the epochs was recognised with astonishment. The stream, which had been seen from Jamaica to Boston (40° 21’ lat.) to traverse the whole vault of heaven on the 12th and 18th of November, 1833, was again observed in the United States in 1834, on the night between the 13th and 14th of November, although on this latter occasion it showed. itself with somewhat less intensity. In Europe the periodicity of the phenomenon has since been manifested with great regularity. Another and a like regularly recurring phenomenon is that noticed in the month of August, the meteoric stream of St. T.awrence, appearing between the 9th and 14th of August. * Humb., Rel. Hist., t. i. pp. 519-527. Ellicot, in the Transactions of the American Society, 1804, vol. vi. p. 29. Arago makes the fol- lowing observations in reference to the November phenomena: “ We thus become more and more confirmed in the belief that there exists a zone composed of millions of small bodies, whose orbits cut the plane of the ecliptic at about the point which our Earth annually occupies between the 11th and 13thof November. It is a new planetary world beginnim to be revealed to us.” (Annuaire, 1836, p. 296.) . AEROLITES. 113 Muschenbroek,* as early as in the middle of the last cen- tury, drew attention to the frequency of meteors in the month of August; but their certain periodic return about the time of St. Lawrence’s day was first shown by Quetelet, ‘Olbers, and Benzenberg. We shall, no doubt, in time discover other periodically appearing streams,t probably about the 22nd to the 25th of April, between the 6th and 12th of * Compare Muschenbroek, Introd. ad Phil. Nat., 1762, t. ii. p. 1061; Howard, On the Climate of London, vol. ii. p. 23, observations of the ear 1806; seven years, therefore, after the earliest observations of Pratides (Benzenberg, iiber Sternschnuppen, s. 240-244) ; the August observations of Thomas Forster, in Quetelet, op. cit. p. 438-453 ; those of Adolph Erman, Boguslawski and Kreil, in Schum. Jahvi., 1838, s. 317-330. Regarding the point of origin in Perseus, on the 10th of August, 1839, see the accurate measurements of Bessel and Erman (Schum. Astr. Nachr., No. 385 und 428); but on the 10th of August, 1837, the path does not appear to have been retrograde ; see Arago, in Comptes Rendus, 1837, t. ii. p. 183. + On the 25th of April, 1095, “innumerable eyes in France saw stars falling from heaven as thickly as hail,” (ut grando, nist lucerent, pro densitate putaretur; Baldr. p. 88), and this occurrence was regarded by the Council of Clermont as indicative of the great movement in Christendom. (Wilken, Gesch. der Kreuzziige, bd. i. 8, 75.) On the 25th of April, 1800, a great fall of stars was observed in Virginia and Massachusetts ; it was “a fire of rockets that lasted two hours.” Arago was the first to call attention to this “trainée d’asteroides,” as a re- eurring phenomenon. (Annuaire, 1836, p. 297.) The falls of aerolites in the beginning of the month of December, are also deserving of notice. In reference to their periodic recurrence as a meteoric stream, we may mention the early observation of Brandes on the night of the 6th and 7th of December, 1798 (when he counted 2000 falling stars), and very probably the enornious fall of aerolites that occurred at the Rio Assu, near the village of Macao, in the Brazils, on the 11th of December, 1836. (Brandes, Unterhalt. fiir Freunde der Phystk, 1825, heft i. s. 65, and Comptes Rendus, t. v. p. 211.) Capocci, in the interval between 1809 and 1839, a space of 30 years, has discovered twelve authenticated cases of aerolites occurring between the 27th and 29th of November, besides others on the 13th of November, the 10th of August, end the 17th of July. (Comptes Rendus, t. xi. p. 357.) It is singular that in the portion of the Earth’s path corresponding with the months of January and February, and probably also with March, no periodic streams of falling stars or aerolites have as yet beem noticed ; although when in the South Sea in the year 1803, I observed on the 15th of March a remarkably large number of falling stars, and they were seen to fall as in a swarm in the city of Quito, shortly before the terrible earthquake of Riobamba on the 4th of February, 1797. From the phenomena I (ti4 _ COSMOS. December, and, to judge by the number of true falls. of aero- lites enumerated by Capocci, also. between the 27th and 29th -of November, or about the 17th of July. _. Although the phenomena hitherto observed appear to haye -been independent of the distance from the pole, the tempera- ture of the air, and other climatic relations, there is, however, “one perhaps accidentally coincident phenomenon which must not be wholly disregarded. The Northern Light, the Aurora ‘Borealis, was unusually brilliant on the occurrence of the splendid fall of meteors of the 12th and 138th November, 1833, described by Olmsted. It was also observed at Bremen in .1838, where the periodic meteoric fall was, however, less remarkable than at Richmond near London. I have mentioned ‘in another work the singular fact observed by Admiral _Wrangel, and frequently confirmed to me by himself,* that when he was on the Siberian coast of the Polar sea, he observed ‘hitherto observed, the following epochs seem especially worthy of ‘remark :— _ 22nd to the 25th of April. 17th of July, (17th to the 26th of July?) (Quet., Corr., 1837, p, 435) 10th of August. 12th to the 14th of November. 27th to the 29th of November. 6th to the 12th of December. . When we consider that the regions of space must be occupied a -myriads of comets, we are led by analogy, notwithstanding the. dif- ‘ferences existing between isolated comets and rings filled with asteroids, to regard the frequency of these meteoric streams with less astonish- ‘ment than the first consideration of the phenomenon would be likely .to excite. * Ferd. v. Wrangel, Reise lings der Nordkiiste von Sibirien in den. Jahren 1820-1824, th. ii. s. 259, Regarding the recurrence of the denser swarm of the November stream after an interval of 38 years, see Olbers, in Jahrb., 1837, s. 280. Iwas informed in Cumana that shortly before the fearful earthquake of 1766, and consequently 33 years (the same interval) before the great fall of stars on the 11th and 12th of November, 1799, a similar fiery manifestation had been observed in the heavens. But it was on the 21st of October, 1766, ‘and not in the beginning of November, that the earthquake oceurred. Possibly some traveller in. Quito may yet be able to ascertain the ‘day on which the voleano of Cayambe, which is situated there, was for the space of an hour enveloped in falling stars, so that the in- habitants endeavoured to appease heaven by religious processions. (Relat. Hist., t. i. chap. iv. p. 307; chap. x. p. 520 and 527.). ABRODITES, “TTS -an Aurora, Borealis, certain: portions’ of- the vault»of sad which were not illuminated, light. up and continue luminous whenever a shooting star passed.over them. ~ The different meteoric streams, each. of which: is mua of myriads. of small cosmical Lodies, probably intersect: our Karth’ s orbit in the same manner as Biela’s comet. Accord- ing to this hypothesis, we may represent to ourselves these asteroid-meteors as composing a closed ring or zone, within which they all pursue one common orbit. The. smaller planets between Mars and Jupiter, present us, if we except Pallas, with an, analogous relation: in their constantly inter- secting orbits. As yet, however, we have.no certain know: ledge. as to whether changes in. the periods at which: the stream becomes visible, or the re‘ardaiions of the phenomena of which I have already spoken, indicate a regular precession or oscillation of the nodes—that is to. say, of the points: sd intersection of the Earth’s orbit and of that of ‘the ring;: whether this ring or zone 2 connected with shooting stars), and those pyrites of Sterli- famak, west of the Uralian Mountains, which are said to have constituted the interior of hailstones,* must both be classed amongst the mythical fables of meteorology. Some few aero- lites, as those composed of a finely granular tissue of olivine, augite and labradorite blended together} (as the meteoric stone found at Juvenas, in the Department de l’Ardéche, which resembled dolorite), are the only ones, as Gustave Rose has femarked, which have a more familiar aspect. These bodies * Gustav Rose, Reise nach dem Ural, bd. ii. s. 202. : + Gustav Rose, in Poggend. Ann., 1825, bd. iv., s. 173-192. Ram- melsberg, Erstes Suppl. zum chem. Handwérterbuche der Mineralogie, 1843, 8.102. “It is,” says the clear-minded observer, Olbers, “a re-’ markable but hitherto unregarded fact, that while shells are found in secondary and tertiary formations, no fossil meteoric stones have as yet. been discovered. May we conclude from this circumstance, that pre- vious to the present and last modification of the earth’s surface no meteoric stones fell on it, although at the present time it appears pro- bable, from the researches of Schreibers, that 700 fall annually ?” (Olbers, in Schum. Jakrb., 1838, 8.329.) Problematical nickelliferous masses of native iron have been found in Northern Asia (at the gold-washing establishment at Petropawlowsk, eighty miles south-east of Kusnezk), imbedded thirty-one feet in the ground; and more recently, in the: Western Carpathians (the mountain chain of Magura, at Szlanicz), both of which are remarkably like meteoric stones. .Compare Erman, Archiv: Sir 9 haftliche Kunde von Russland, bd. i, s. 315, and Haidinger, » Bericht iiber Sdamiczer Schiirfe in. Ungarn. ; any 120 -COSMOS, | contain, for instance, crystalline substances, perfectly similar to those of our earth’s crust ; and in the Siberian mass of meteoric iron investigated by Pallas, the olivine only differs from common olivine by the absence of nickel, which is re- placed by oxide of tin.* As meteoric olivine, like our basalt, contains from 47 to 49 per cent. of magnesia, constituting, according to Berzelius, almost the half of the earthy com- - ponents of meteoric stones, we cannot be surprised at the great quantity of silicate of magnesia found in these cosmical bodies. If the aerolite of Juvenas contain separable crystals of augite and labradorite, the numerical relation of the consti- tuents renders it at least probable, that the meteoric masses of Chateau-Renard may be a compound of diorite, consisting of hornblende and albite, and those of Blansko and Chanton- nay compounds of hornblende and labradorite. The proofs of the telluric and atmospheric origin of aerolites, which it is attempted to base upon the oryctognostic analogies presented by these bodies, do not appear to me to possess any great weight. Recalling to mind the remarkable interview between New- ton and Conduit at Kensington,t I would ask why the ele- mentary substances that compose one group of cosmical bodies, or one planetary system, may not in a great measure be iden- tical? Why should we not adopt this view, since we may conjecture that these planetary bodies, like all the larger or smaller agglomerated masses revolving round the sun, have been thrown off from the once far more expanded solar atmo- sphere, and been formed from vaporous rings describing their orbits round the central body? We are not, it appears to me, more justified in applying the term telluric to the nickel and iron, the olivine and pyroxene (augite), found in meteorie stones, than in indicating the German plants which I found beyond the Obi as European species of the flora of Northern Asia. If the elementary substances composing a group of cosmical bodies of different magnitudes be identical, why * Berzelius, Jahresber., bd. xv. s. 217 und 231, Rammelsberg, Hand- worterb., abth. ii, s. 25-28. + “Sir Isaae Newton said he took all the planets te be composed of the same matter with the Earth, viz., earth, water, and stone, but vari- ously concocted.”—Turner, Collections for the History of Grantham, containing authentic Memoirs of Sir Isaac Newton, p. 172. ) AEROLITES, 121 should they not likewise, in obeying the laws of mutual at- traction, blend together under definite relations of mixture, composing the white glittering snow and ice in the polar zones of the planet Mars, or constituting in the smaller cos- mical masses mineral bodies enclosing crystals of olivine, au- gite, and labradorite? Even in the domain of pure conjecture we should not suffer ourselves to be led away by unphiloso- phical and arbitrary views devoid of the support.of inductive reasoning. - Remarkable obscurations of the sun’s dise, during which the stars have been seen at mid-day (as for instance in the obscuration of 1547, which continued for three days, and occurred about the time of the eventful battle of Mihlberg), eannot be explained as arising from volcanic ashes or mists, and were regarded by Kepler as owing either to a materia cometica, or to a black cloud formed by the sooty exhalations of the solar body. The shorter obscurations of 1090 and 1203, which continued the one only three and the other six hours, were supposed by Chladni and Schnurrer to be occa- sioned by the passage of meteoric masses before the sun’s dise. Since the period that streams of meteoric shooting stars were first considered with reference to the direction of their orbit as a closed ring, the epochs of these mysterious celestial phenomena haye been observed to present a remark able connection with the regular recurrence of swarms of shooting stars. Adolph Erman has evinced great acuteness of mind in his accurate investigation of the facts hitherto observed on this subject, and his researches have enabled him to discover the connection of the sun’s conjunction with the August asteroids on the 7th of February, and with the No- vember asteroids on the 12th of May, the latter period corresponding with the days of St. Mamert (May 11th), St. Pancras (May 12th), and St. Servatius (May 13th), which, according to popular belief, were accounted “ cold days.” * * Adolph Erman, in Poggend. Annalen, 1839, bd. xlviii. s. 582-601. Biot had previously thrown doubt regarding the probability of the No- vember stream reappearing in the beginning of May (Comptes Rendus, 1836, t. ii. p. 670). Midler has examined the mean depression of tempera- ture on the three illnamed days of May by Berlin observations for 86 years (Verhandl. des Vereins zur Beford. des Gartenbaues 1834, s. 377), and found a retrogression of temperature amounting to 2°°2 F. from the 122 ' COSMOS. The Greek natural philosophers, who were but little dis. posed to pursue observations, but evinced inexhaustible fer. tility of imagination in giving the most various interpretation. of half-perceived facts, have, however, left some hypotheses regarding shooting stars and meteoric stones, which strikingly accord with the views now almost universally admitted of the cosmical process of these phenomena. ‘“‘ Falling stars,”’ says Plutarch, in his life of Lysander,* “‘are, aécording to the opi- nion of some physicists, not eruptions of the ‘etherial fire extinguished in the air immediately after its ignition, nor yet an inflammatory combustion of the air, which is dissolved im. large quantities in the upper regions of space; but these me- feors are rather a fall of celestial bodies, which, in consequence 6f a certain intermission in the rotatory force, and by the impulse of some irregular movement, have been hurled down not only to the inhabited portions of the Earth, but also beyond it into the great ocean, where we cannot find them.” Diogenes of Apollonia} expresses himself still more explicitly. According to his views “Stars that are invisible, and conse- 11th to the 18th of May, a period at which nearly the most rapid ad- vance of heat takes place. It is much to be desired that this phenomenon of depressed temperature, which some have felt inclined to attribute to the melting of the ice in the north-east of Europe, should be also inves- tigated in very remote spots, as in America, or in the Southern Hemi- sphere. (Comp. Bull. de 1 Acad. Imp. de St. Pétersbourg, 1843, t. i., No. 4.) * Plut., Vite par. in Lysandro, cap. 22. The statement of Dama- chos (Daimachos), that for 70 days continuously there was a fiery cloud seen in the sky, emitting sparks like falling stars, and which then, sink- ing nearer to the earth, let fall the stone of Mgos Potamos, “which, however, was only a small part of it,” is extremely improbable, since the direction and velocity of the fire cloud would in that case of neces- sity have to remain for so many days the same as those of the earth; and this in the fire ball of the 19th of July, 1686, described by Halley (Trans., vol. xxix., p. 163) lasted only afew minutes. It is not altogether certain whether Daimachos, the writer, zepi evoeBeiac, was the same per- son as Daimachos of ‘Platzea, who was sent by Seleucus to India to the son of Androcottos, and who was charged by Strabo with being “a speaker of lies” (p. 70, Casaub.). From another passage of Plutarch (Compar. Solonis c. Cop. cap. 4) we should almost believe that he was. At all events we have here only the evidence of a very late author, who wrote a century and a half after the fall of aerolites occurred in Thrace, and whose authenticity is also doubted by Plutarch. = ““+ Stob., ed. Heeren, i. 25, p. 508; Plut., de plac. Philos., ii. 18. AEROLITEs. 123 ss havé io name, move im space together with those are visible. These invisible stars frequently fall to the. earth and ‘are extinguished, as the stony star which fell burn- ing at Agos Potamos.” The Apollonian, who held all other stellar bodies when luminous to be of a pumice-iike nature, probably grounded his opinions regarding shooting stars and meteoric masses on the doctrine of Anaxagoras the Clazome- nian, who regarded all the bodies in the universe “as fragments of ‘rocks, which the fiery ether in the force of its gyratory motion had torn from the Earth and converted into stars.” In the Ionian school, therefore, according to the testimony transmitted to us m the views of Diogenes of Apollonia, aero- lites and stars were ranged in one and the same class: both, when considered with reference to their primary origin, being equally telluric, this being understood only so far as the earth was then regarded as a central body,* forming all things around it in the same manner as we, according to our present views, suppose the planets-of our system to have originated in the expanded atmosphere of another central body—the Sun. These views must not, therefore, be confounded with what is commonly termed the telluric or atmiospheric origin of meteoric stones, nor yet with the singular opinion of Aris- totle, which supposed the enormous mass of Agos Potamos to have been raised by a hurricane. ‘That arrogant spirit of incredulity, which rejects facts without attempting to in- vestigate them, is in some cases almost more injurious than an unquestioning credulity. Both are alike detrimental to the force of investigation. Notwithstanding that for more than ' * The remarkable passage in Plut., de plac. Philos., ii. 18, runs thes: “ Anaxagoras teaches that the surrounding ether is a fiery substance, which by the power of its rotation tears rocks from the earth, inflames and converts them into stars.” Applying an ancient fable to il- lustratea physical dogma, the Clazomenian appears to have ascribed the fall of the Nemean Lion to the Peloponnesus from the Moon to such a rotatory or centrifugal force. (Alian., xii. 7; Plut., de facie in orbe Lune, ¢, 24; Schol. ex Cod. Paris. ‘in Apoll. Argon., lib. i. p. 498, ed. Schaef. tii. p. 40; Meineke,