UBRARY 
 
 8NIVERSITY OF SCIENCES 
 CALIFORNIA J UBRAJ5Y 
 

 Proceed in' 
 
 ' THE 
 
 POUUHKEEPS1E SOCIETY 01 
 
 Natural Science, 
 
 VCMU L 
 
QE 
 
 VS/2 
 
 CES 
 LIBRARY 
 
 STUDIES 
 
 UPON THE 
 
 INCLINATION OF THE EARTH'S Axis, 
 
 BY CHARLES B. WARRING. 
 
 Read before the Poughkeepsie Society of Natural Science, 
 Nov. 29, 1876. 
 
 From the most remote period known to history or tradition, 
 Summer and Winter, Spring-time and Autumn have divided 
 the year as now. During all the centuries since their cause, the 
 inclination of the earth's axis, has been unchanged. Its great 
 importance, an inability to account for it, and an undue esti- 
 mate of the fixedness of axial direction have induced in 
 many, the belief that it is due to a direct exertion of Divine 
 power. But as the axes of all the planets and the Sun are 
 inclined at various angles, often not of the least advantage 
 in reference to seasons j^as, for example, in the Sun and 
 MoonJ it seems that their obliquity must be due to some force 
 active before the historical or traditional period began, per- 
 haps at the formation of the system. This leads to an 
 inquiry into the mode of its genesis, and the world's as a 
 part of it. 
 
 The theory suggested by Kant, and more fully developed 
 by Laplace, accounts, on well-known mechanical principles, 
 for so many of the phenomena of the solar system, and has, 
 according to the spectroscope, so good a basis in the present 
 existence of true nebulae, that it is generally admitted to be 
 wonderfully near the truth, it not the truth itself. The re- 
 
luctance of some to heartily accept it, arises from the fact 
 that while it seems to account for so many phenomena, it not 
 only fails to do so upon closer examination but actually ap- 
 pears to be contradicted by them. 
 
 For example, the sun and all the planets, on this theory, 
 ought" to move in one direction, both on their axes and in 
 their orbits; and so they do pretty nearly. Yet, when 
 accuracy of statement is required, we are told that they all 
 vary, the direction of no two being exactly the same. The 
 axial motion of the earth, for example, crosses the orbital at 
 an angle of 231 ; and, with variations in the angle of 
 crossing, the same is true of all. The orbits ought to lie in 
 the plane of the solar equator ; but they do not : nor do any 
 two of their planes coincide with each other. Not one 
 planet has its axis perpendicular to its own orbit ; although, 
 according to the theory, they all ought. The orbits, more- 
 over, ought to be circular ; bat all are more or less eccentric. 
 All the satellites ought to be in the planes of the equators of 
 their primaries; but I doubt if one is really so, while 
 Saturn's eighth satellite is about 12, and our moon nearly 
 181, out of place. To crown it all, the moons of Uranus 
 and Neptune actually go backward. 
 
 If Laplace's theory be true there must be some way to ac- 
 count for these apparent contradictious. 
 
 My attention was drawn to this subject nearly two years 
 ago; and the conclusions at which I arrived, as \sell as the 
 reasons on which they are founded, I embodied in my " Cos- 
 mology," an essay which forms Part III of The Miracle of 
 To-Day. 
 
 I therein showed that a key to all these perplexing pecul- 
 iarities is found in the addition to the Nebular Hypothesis of 
 one condition, to wit, that in the gas-like mass from which 
 the solar system was evolved certain elevations or upheavals 
 occurred from time to time, rising and subsiding like waves 
 upon a sea. 
 
 Such movements seem to be normal in our system. They 
 
bave been noticed in that semi-nebulous planet Saturn by 
 Schroster, the two Bonds, Herschel and others, and been 
 found, by actual measurement, to rise more than 1,000 miles. 
 They present the characteristic form of our earth's circum- 
 polar upheavals, for they are not abrupt, but rise so gently 
 that it is impossible to mark their precise limits, resembling 
 the tidal wave in mid-ocean. Similar movements are more 
 than suspected in Jupiter. The spectroscope reveals them 
 in the Sun exhibiting, however, an intensity and abruptness 
 in harmony with the energetic action there going on. Nor is 
 our present solid earth free from them. They are seen in 
 the slow elevation of Sweden, and of many other places. In- 
 deed, to quote the enthusiastic language of Darwin, " daily 
 it is forced home upon the mind of the Geologist, that 
 nothing, not even the wind that blows, is so unstable as the 
 crust of the earth." 
 
 Finding then, that there are now actually in existence 
 masses of nebulous substance, such as the theory requires, 
 which, if subject to the laws of matter and affected by these 
 upheavals, would evolve a system like our own, and account 
 for all its apparent anomalies and seeming contradictions, I 
 see no escape from the belief that the Nebular Hypothesis is 
 a true statement of its mode of formation. Other evidence 
 than this, it is in the nature of the case impossible to obtain. 
 For similar reasons astronomers accept, as true, the existence 
 of a central force holding the planets in their places. No 
 one has seen or can see this force, although everybody be- 
 lieves in it, because, if true, it accounts for the facts to 
 which it is applied. 
 
 On condition then, that the earth and moon were once one 
 mass of nebulous matter, subject to the laws of motion, I 
 showed that the axis of the earth at the time of separation 
 from the moon was inclined not more than 5 deg. 9 min., or, 
 in other words not more than is the orbit of the moon now. 
 
 But my studies in a parallel, but entirely independent line 
 of thought, rendered me doubtful whether the earth's axis 
 
 PBOC. I'O'K. SOC. NAT. SCI. VOL. I. 
 
was not at tLat time very considerably less inclined than 5 
 cleg. 9 rnin., and hence I was led to reconsider the matter. 
 This brought me into regions hitherto unexplored. I took 
 for guidance tvro principles ; first, the past and present uni- 
 formity of the laws of motion, and second, a like uniformity 
 of the laws of organic being; in other words, that both 
 classes of laws have operated, since they came from the 
 great Lawgiver, as they operate to-day. Hence, relying 
 upon the belief that the earth and the moon are, and ever 
 have been as obedient to gravitation, as the tiniest dew-drop 
 that gathers on a blade of grass, and that the genera and 
 species now living, identical with the ante-glacial vegetation, 
 are no more and no less subject to the influence of light than 
 were their ancestors, I have followed the clue which these 
 have given me, and pursued my investigation, undismayed 
 by the greatness of the results, and undisturbed by their 
 novelty. 
 
 The object of this paper is to lay these results before you 
 and to explain the manner in which they were attained, as 
 well as to present some 'other matters intimately connected 
 with the same subject. 
 
 I started with the self evident proposition that, if the 
 earth was formed from nebulous matter in obedience to the 
 laws of motion and gravitation, undisturbed by any other 
 force, its axis must necessarily have been perpendicular to 
 the plane of its orbit. 
 
 Here we are met on the threshold of our inquiry by the 
 question, how could a belt become a spheroid? Having 
 answered that, we next shall seek to show how the axis, 
 which was normally perpendicular, became inclined. In the 
 third place, we shall endeavor to discover how great this in- 
 clination was, up to the moment of the earth's existence 
 separate from the moon. If I mistake not, it did not then 
 exceed 1 SO 7 ; and this brings us face to face with the fourth 
 inquiry, When did the increase to its present obliquity occur ? 
 And, lastly, in this part of our subject, What was the cause 
 of that increase 2 
 
The last two questions lead to the examination of the geo- 
 logical record. We shall study the influence of light upon 
 plant-life especially, not neglecting its effects upon aniinal- 
 life, and from these endeavor to discover the actual distribu 
 tion of light in those periods. We shall also inquire into the 
 cause of the Glacial period, and shall eximins Mr. C roll's 
 theory with special reference to the crucial test which he lias 
 proposed. 
 
 To complete our " study," we shall then seek a solution of 
 an apparent mechanical difficulty, and lastly set forth a pos- 
 sible explanation of the circumpolar upheavals. 
 
 First, then, how could a belt become a spheroid ? 
 
 In a nebula left solely to the influence of gravitation and 
 the laws of motion, the ring evolved would be homogeneous 
 and of uniform section. Consequently, if undisturbed by 
 any external force, it would continue in that condition for- 
 ever, and it would move in the same direction as the central 
 mass (which we will style the helioid,) about their common 
 centre. 
 
 The distance between the two, at first, was very small, 
 and for this reason, in accordance with Kepler's law, their 
 times of revolution, or their angular velocities, must have 
 been nearly equal. A point, therefore, on the ring opposite 
 a point on the helioid, would remain nearly opposite for a 
 very long time. In fact, there will at first be but little rela- 
 tive change of position for many complete revolutions. This 
 js a matter of very great importance, since in connection with 
 fhe temporary character of the upheavals, it completely 
 ^eliminates that compensation which would otherwise come 
 from the points being half the time on one side of the center 
 X)f gravity, and half on opposite sides, such a change of po- 
 sition being the marrow of Lagrange's theorem as to the 
 stability of our system. 
 
 If now. in this early stage, an upheaval occurred upon the 
 helioid near its equator, it is evident that it would exert 
 ,an increased mftucnce upon tlae rjpg, depending upon jty. 
 
mass and distance. It would accelerate the atoms bohind it, 
 and retard those in front. Hence, would result a crowding 
 together of the atoms of the ring, thus forming an enlargement, 
 or nucleus, at a point nearly opposite the upheaval. The 
 atoms behind would have their centrifugal force increased, 
 while those in front would have theirs diminished. From this 
 would arise a condition shown in Fig. 1, which represents an 
 equatorial section of the system, just after the mass M, has 
 been upheaved and the nucleus N begun to form. 
 
 Fiff 1. 
 
 A nucleus once made, its own attraction would continue 
 to draw to itself the ring-matter with ever increasing power 
 until the whole belt, if undisturbed, flowed into it. 
 
 Such a gathering would generate a rotation in the same 
 direction as the helioid, but with a velocity at first very 
 small. 
 
 Here I may remark, although outside of the question be- 
 fore us, that the present rate of axial motion of any planet, 
 is evidently derived, first, from the mass and position of the 
 upheaval, since these determine the difference of motion in 
 the two portions of the belt ancl consequently the initial 
 
rotation ; secondly, from the mass and diameter of the ring, 
 for the one is the measure of the attractive force, and the 
 other determines the falling distance of the atoms and hence, 
 their velocity. The diameter of the ring also determines the 
 effect of the attraction of the upheaval and of the nucleus 
 upon the centrifugal force, and hence the distance of the 
 points of impact of the ring atoms, each side of the medial 
 line. Lastly, after the ring had been absorbed, a further in- 
 crease of axial velocity \vas produced by the radial contrac- 
 tion of the embryo plaaet, continuing indeed to the present 
 moment. The present length of the day of any planet is a 
 function of all these quantities, less the force lost by the 
 conversion of energy into other forms. Kirkwood's Analogy 
 takes notice only of the masses and distances of the planeU 
 themselves and therefore can give only approximate results. 
 This is an inviting field into which 1 must wander no further 
 to-night. 
 
 We have seen how a belt could become a spheroid, but we 
 are reminded that if left to itself, its axis would be perpen- 
 dicular to the plane of its orbit, and would remain so. How 
 could it first become inclined ? 
 
 As the ring-matter was pouring into the nucleus N, Fig. 1, 
 on the one side, and being gathered up on the other, there 
 were, in effect, two streams moving in opposite directions, 
 and, hence, there resulted a lateral pressure which caused it 
 to elongate as in Fig. 2, just as a bar of iron under the 
 
 Fig 2. 
 
 blows of a hammer, elongates in the direction of the axis 
 about which it rotates, Tbis evidently would be-in, a Plate of 
 
8 
 
 unstable equilibrium and, therefore, if while the process was 
 going on, an upheaval occurred at some distance above the 
 equator of the helioid as at M, Fig. 3, it would cause the 
 
 Fiff. 3. 
 
 planet to become inclined in the direction indicated by the 
 dotted line, a movement which, once commenced, would be 
 aided by the attraction of the central body. 
 
 A succession of such masses as M, properly placed would 
 tilt the spheroid to any extent, from 0' to 180. If this 
 change of position exceeded 90, the direction of rotation 
 would be reversed and then would result a retrograde move- 
 ment like that of the moons of Uranus, as shown in my 
 Cosmology. 
 
 We can thus see how, on known mechanical principles, the 
 nebulous spheroid from which the earth and moon were long 
 afterward to be evolved, could obtain a greater or less ob- 
 liquity. 
 
 As soon, however, as the ring-matter was all gathered and 
 the lateral pressure in consequence, ended, the embryo planet 
 began to assume an oblate form, thus generating greater 
 stability or in other words a stronger power of resistance to 
 any external force wliich might thereafter tend tQ change its 
 8,xiaJ direction. 
 
From this nebulous body a belt was eventually separated, 
 which of necessity lay in the plane of the equator of the mass, 
 and from it, in the manner already considered, the moon was, 
 in due time, evolved. At this time the axes of the earth and 
 moon, if left to themselves, must have been parallel, and the 
 orbit of the latter, have been in the plane ot the other's equator. 
 We know the axes now are not parallel and the moon's orbit 
 is not in the plane of the earth's equator. Hence we are 
 absolutely certain that two of these have undergone a change 
 of position since that time of avulsion. The moon's axis is 
 nearest the normal inclination, hence, a priori, it is most 
 reasonable to believe that it has undergone little or no change 
 in that respect. If this be so, then the earth at that time 
 was inclined no more than the moon is now, i. e. H. The 
 same doctrine of upheavals will readily bring us through all 
 the mechanical difficulties to the present condition. It' there 
 were such movements in the moon, they would, if polar, tilt 
 the moon yet further from the perpendicular ; hence I con- 
 clude that none occurred. But if polar upheavals of suffi- 
 cient size occurred upon the earth, they would first tilt 
 the moon's orbit further from its position ; and, second, by 
 the reaction of the moon, as well as by solar attraction, tilt 
 the world to an extent depending upon their size and 
 duration. The world is tilted 22 further over, and the orbit 
 of the moon has moved from its then position to 5 9'. In 
 some way and at some time time a change of position really 
 occurred. The one which I have laid before you seems to me 
 the easiest and most natural way. The change could not occur 
 without outside force of some kind, and I know of none that 
 "we have a right to invoke save that, whatever it is, 
 which has, during all the past to the present day, manifested 
 itself in immense uplifts either* of the nebulous matter or of 
 the solid crust. By outside force, I ought perhaps to say, 
 is meant some other force than the attraction of gravitation 
 and the laws of motion. 
 
 I conclude, then, as at least the most probable result, that 
 
10 
 
 when the lunar belt left the earth the axis of the latter was 
 inclined not more than U, and that consequently the increase 
 to 231 occurred at some subsequent period. 
 
 Our next inquiry is, Is there any evidence of the existence 
 of this perpendicular axis ? 
 
 I remark, first, that if such a condition continued until the 
 earth had become covered with plants and peopled with ani- 
 mals, we should expect indications of it in the early history 
 of our globe. We know, however, that if it did so continue, 
 it ceased before the historic period commenced. 
 
 A careful examination of all possible causes of such a 
 movement as increasing the obliquity from H to 23*, leads 
 to the conclusion that no physical cause would be adequate 
 to such an effect, except the most enormous polar upheavals 
 large enough to make our globe prolate. Such an up- 
 heaval would engender intense cold. Hence, if such an 
 event occurred, there should be found somewhere between 
 the earlier conditions of plant and animal life, and the historic 
 period a time of world- wide cold. Conversely, it* on exami- 
 nation we find that, in the earlier periods, conditions did actual- 
 ly prevail which no ingenuity can account for on any other sup- 
 position consistent with uniformity in the action of the laws 
 of life, that these conditions were followed by polar upheavals 
 (of whose extent we know comparatively nothing) accompa- 
 nied by great cold, and if we find too that the orbit of the 
 moon has moved away from that supposed normal position 
 precisely as it would have done had it been acted upon by 
 the attraction of such upheavals, then I submit that the proof 
 of such an axial change, of its cause and epoch, approaches 
 demonstration. 
 
 Before examining the evidence, I would call attention to 
 the fact that the question is not in the least whether the 
 earth has ever changed the direction of its axis. That is a 
 conclusion absolutely involved in the once nebulous condition 
 of our Cosmos. I remark also that it is not a change in the 
 position of the pole on the earth's surface of which .1 am 
 
II 
 
 speaking. It is its direction in space with which I am concerned. 
 And, lastly, the mechanical difficulties are not lessened by 
 placing this change in the remote past, nor by supposing that 
 it occurred while our globe was in a gaseous condition. It 
 would require as much force at one time as at another, and 
 in either case it was, humanly speaking, an effort of infinite 
 power ; Cosmically speaking, it was the merest trifle. 
 
 We shall now turn to the records which are found in the 
 rocks, and seek to discover what is the story which the 
 fossils tell. 
 
 Looking over the past, we are first struck by the marvel- 
 ous uniformity of plants and animals in all latitudes. "No 
 marked difference between the life of the Primordial period 
 in warm and cold latitudes has been observed," (Dana's 
 Manual, p. 181.) "Identical species are found in the strata 
 near Lake Winnipeg and in Alabama. The living species in 
 the waters between the parallels of 30 and 45 were in part 
 the same with those that flourished between 65 and SO /' (p. 
 253.) When we come down to the Carboniferous Age, we find 
 according to Lesquereux (Bulletin of U. S. Geol. and Geog- 
 Survey, 1876, p. 247,) "a uniformity of vegetation over the 
 whole northern hemisphere, if not over the whole surface of 
 the earth." 
 
 Authorities differ as to the degree of heat indicated by the 
 carboniferous flora. They probably did not require a torrid, 
 but a decidedly warm climate. It is not, however, the 
 temperature to which I wish to direct your attention, but the 
 fact that the same plants and animals grew in all latitudes, 
 evidence of which can be multiplied to an indefinite extent. 
 
 As to the identity, or, at least, intimate relationship of 
 species in places of very widely different latitudes, I find Sir 
 Charles Lyell, on page 217 of his Principles of Geol., 1873, 
 saying : " The same genera, and, to some extent, the same 
 species of ammonites, and some other shells, occur also in 
 formations of the same age in India. In a northerly di- 
 rection the same formations reach within 13 2 of the Dole." 
 
12 
 
 * * * # * * " Remains of a large Ichthyosaurus, of 
 Liassic type, were brought from latitude 77 16', by Sir Ed- 
 ward Belcher. Others were found in Jurassic strata, in 
 Spitzbergen, in latitude 78 30V 
 
 In this uniformity of animal, and, more especially, of plant 
 life, there will be found, if I mistake not, indications of the 
 highest importance as to the position of the earth's axis, i. e., 
 as to its obliquity to the ecliptic. I see no evidence that 
 latitudes have ever changed. 
 
 Next to food, heat and light are essential to the growth 
 and mature development of organisms. Scientists in refer- 
 ence to the early history of our globe have confined their ef- 
 forts to accounting for the uniformity of heat, utterly ignor- 
 ing the eifects of light. Both will be found yielding evi- 
 dence as to the question which I am endeavoring to solve, but 
 light far more than heat. 
 
 The earth receives from the sun both light and heat. The 
 latter enters our atmosphere freely, but cannot as easily es- 
 cape. Prof. Tyndall, by a series of beautiful experiments 
 upon the passage of heat from sources of low temperature 
 through vapors and gases, has shown that even a small 
 amount of watery vapor in the atmosphere acts like a thick 
 blanket to keep in the heat, and that other vapors and gases, 
 as carbonic acid, for example, behave in the same manner^ 
 and even with greater intensity. 
 
 These important discoveries render it possible to see how 
 the temperature of the globe might vary exceedingly at 
 different epochs, although receiving equal amounts of heat 
 from the Sun. On the same principle, plants under glass are 
 kept warmer than those in the open air. The glass, like the 
 vapors, lets the solar heat in, but does not permit that radi- 
 ated from the plants and the soil in which they stand, to 
 escape. 
 
 It is well known that the arrangement of the land, either 
 as to elevation or extent, and the volume and direction of 
 ocean- currents, exert a controlling influence on the tempera- 
 
13 
 
 tare of localities ; and, hence, this does not afford any very 
 certain indication of the amount of heat received from the 
 Sun. 
 
 I shall say nothing of internal heat, because, although the 
 world had once been intensely hot, yet, at the time of 
 the coal deposits, and, probably long before, it had ceased 
 to radiate any appreciable quantity. 
 
 If the atmosphere in the earlier periods was freer from car- 
 bonic acid and watery vapor than DOW, and the axis 
 was inclined, as at the present day, the climate of the arctic 
 regions must have been much colder, and, vice versa, if these 
 were more abundant, the temperature must have been warm- 
 er ; upon the whole, therefore, the distribution of heat is 
 affected so greatly by influences independent of the earth's 
 axial position, that no conclusion of value can be drawn from 
 it in reference to the obliquity. 
 
 We are not, however, left without any clue. There is the 
 other force of which I have spoken, and which, thus far, in 
 all attemps to solve this problem, has been ignored. Its im- 
 portance to plant life is scarcely second to that of heat, since 
 disease and death in nearly all cases, inevitably follow the 
 absence, or too small quantity of either. 
 
 This force is LIGHT. 
 
 If plants are kept in a cold, dry place, they may long be 
 unaifected by the absence of light, but it becomes vitally 
 important if they are surrounded by an atmosphere " warm 
 and moist " as in Miocene and pre-M iocene times. Few plants 
 deprived of this necessary stimulus, will long survive in such 
 conditions, as every gardener can bear witness. 
 
 Light at any point may be diminished by clouds, or mist, 
 but in no way, increased. The total annual amount falling 
 upon a given surface, as a square yard, is determined solely 
 by the latitude, save so far as it may be affected by clouds, 
 and consequently it is independent of the inclination of the 
 earth's axis. But the distribution of that light, e. g., whether 
 it be concentrated into a short period of uninterupted sun- 
 
14 
 
 shine, followed by a total absence of solar rays for a long po- 
 lar night, depends wholly upon the inclination. 
 
 Hence, if we know how such distributions would affect 
 plant-life, and if we also know what was the flora of those 
 early periods, we have the means of determining whether the 
 earth's axis was yet in the position which it had w T hen the 
 lunar belt was avulsed, or whether it had attained its present 
 obliquity. Most plants require what may be styled a speci- 
 fic amount of light. Few do well in the shade. From the 
 character of the early vegetation, it is evident that the climate 
 was " warm, moist and equable," (Dana, Ly ell, &c.) If plants 
 are left for months in a warm, moist and dark cellar, 
 it is well known that their foliage becomes colorless and un- 
 natural. I have never heard of their flowering, and it seems 
 impossible that they could mature their seed. The same 
 plants will not do well under these conditions and under the 
 direct and full light of the Sun. If the axis, in the Cretaceous 
 for example, was inclined 231, the condition as to light 
 would be, say, in latitude 80, for four months as in the cel- 
 lar, and for four months as in the direct sun-light. If they 
 really lived and did well, the flora must have been peculiar 
 to those latitudes. But we find all along down to the Mio- 
 cene certainly, in each epoch, a wonderful sameness of species 
 all over the world the same trees " flourishing luxuriantly " 
 from Florida to Spitzbergen, (latitude 79) and beyond. 
 
 In Spitzbergen, if the axis was then inclined as now, the 
 night, " warm and moist," was four months long. It is incon- 
 ceivable that under such different circumstances, as to this 
 powerful element in plant evolution, no new types were 
 formed fitted to these extremes. 
 
 It is said that Arctic plants are found on the tops of high 
 mountains, where, although they have Arctic cold, they are 
 also exposed to days and nights of comparatively equal length, 
 and that they flourish there as well as in northern latitudes 
 with their long winter nights. 
 
 Admitting the identity of the species, which is question- 
 
15 
 
 able, still the cases are not analogous. The Arctic plants, 
 accustomed to a stagnation of six to nine months' duration, 
 may well be indifferent as to where that time is spent, 
 whether in the cold and darkness of an arctic night, or the 
 cold and light of a lower latitude. But the plants of the 
 Carboniferous Age were not polar plants at all, but tropical, 
 nor were they accustomed to a sleep of six or nine months, 
 nor at that remote period was there any Arctic cold to pro- 
 duce hibernation, but a * warm, moist, equable atmosphere, 1 
 in which they ' flourished luxuriantly.' 
 
 Mutatis mutandis, the same remarks apply to the lew 
 plants of the temperate zone that have straggled to the far 
 north (Smith's Sound), \vhosc dwarfed and scanty growth is 
 in in marked contrast to the luxuriant growth of the coal- 
 forming period. In like manner stand in sharp opposition 
 the vigorous growth on Spitzbergen, of which I have spoken, 
 and the dwarfed willows that are to-day their successors. 
 
 Moreover if then, as now, there were long days and nights 
 varying from four months of consecutive sunlight, to as many 
 months of darkness, it is utterly impossible that there could 
 have been any great " evenness " of temperature. For al- 
 though there was an enormous amount of carbonic acid in 
 the air, its only effect was to make the process of refrigeration 
 in the long nights more slow. It could add nothing to the 
 heat. The temperature would still be dependent upon the 
 sun or ocean currents. At most, the latter could add only as 
 much heat in winter as in summer (they would really add 
 less) ; consequently the difference which wonld arise from a 
 steady addition of solar heat for four months and a total ces- 
 sation for an equal time, must have been very considerable. 
 We know that the average temperature of those regions at 
 the present time varies between the coldest and the warmest 
 month nearly 80. This however does not give a just idea of 
 
 * Darwin, Origin of Species, p. 338, says, "It should, however, be observed that 
 hese plants are not strictly Arctic forms ; for, as Mr. H. C. Watson has remarked, 
 'in receding from polar towards equatorial latitudes, the Alpine ov Mountain 
 floras really become less and less Arotio.' " 
 
16 
 
 the true difference, for the thermometer is carefully shielded 
 from the direct rays of the sun while the vegetation has no 
 such protection. Hence with an axis inclined as now, uni- 
 formity of temperature was impossible. 
 
 But if tho axis was then nearly perpendicular, the climate 
 could not have been other than equable. The same amount 
 of heat being received each day from the sun and, the same 
 amount being each night radiated into space, the temperature 
 must have been uniform all the year. 
 
 Whether the result was a warm or a cold climate, it con- 
 tinued without variation, until internal forces produced either 
 a change of the altitude of the earth's surface or of its 
 arrangement. 
 
 That the result of such days and nights as the world then 
 had, was not cold, is shown, not merely by the flora of arctic 
 lands, but by the corals of arctic waters. Indeed these are 
 no small evidence of the absence of long nights where they 
 lived. It is well known that they die below a certain depth. 
 Dana, page 118, Corals and Coral Islands, says, 
 
 " As to the origin of this small range in depth about 120 
 feet temperature must be admitted as a cause. Yet it can 
 hardly, in this case, be the only cause. The range of tem- 
 perature, 85 to 74, gives sufficient heat for the development 
 of the greater part of reef species, yet the temperature at the 
 100 feet plane, in the Middle Pacific, is mostly above 74." 
 
 So it is not lack of warmth that kills these creatures, nor 
 is it any impurity in the wat?r, for certainly the impurities 
 do not undergo any such corresponding increase of intensity. 
 The pressure is not an element affecting creatures that are 
 composed of tissues filled with water, and not with air. The 
 only conceivable, variable element capable of producing any 
 effect, is light. The fact that corals flourished is strong cor- 
 roborative proof that the polar waters were not deprived of 
 light for consecutive months. 
 
 Nor is it an objection to this view that the corals are 
 destitute of organs of sight, for in no case is the health or 
 
17 
 
 vigor affected through the eyes of any creature, and plants, 
 whose sensibility is marvelous, are as destitute of such or- 
 gans as the Corals. 
 
 It is very true that there was during the Mesozoic and the 
 Tertiary, a gradual hardening of climate, or lowering of tem- 
 perature, but this would inevitably occur from the gradual 
 loss of carbonic acid and watery vapor and, perhaps, of 
 other impurities. But the vegetation of these northern lands, 
 all along, indicates uniformity of light and not extremes of 
 temperature. 
 
 The change in the flora of those regions during that time 
 was what was to have been expected, if the days and nights 
 remained equal, while the temperature underwent a secular 
 fall, and the air grew drier and purer. 
 
 In view, then, of the records of Geology I think I am justi- 
 fied in concluding that until the end of the Tertiary 
 there were no such long nights in polar regions, as there 
 are now. 
 
 It may be said that the amount of light which in a year 
 falls upon a square foot in Florida for example, is four times 
 as great as that which falls upon the same space in Spitz- 
 bergen. This statement is equally true whether the 
 obliquity of the axis was or 23 i for as I have said, the 
 obliquity does not effect the total quantity of light. In 
 the former case, it would be uniformly distributed, equal days 
 following equal nights, while in the latter, there would be 
 the greatest possible variation, and this, continued for cen- 
 turies, would prevent that uniformity of vegetable and animal 
 life which is known to have prevailed in the Miocene and 
 before, in all latitudes. 
 
 It appears to me quite doubtful whether the polar plants 
 of that period could have continued their kind at all, if they 
 had to pass four months in darkness in a " warm and moist " 
 place. The fact of their continued existence is strong proof 
 that no such nights prevailed. 
 
 *I have discussed this which tray Ire styled the biological rart of the 
 question, at greater length in my * Cosmology," in reference to the effects of light 
 upon plants and animals. 
 
18 
 
 Ft may be said that in any case there must have been a: 
 great inequality between the polar and the equatorial 
 amount of heat received from the sun. 
 
 To this I would reply : If the air was rich in carbonic 
 acid, and if the path of the sun from tropic to tropic 
 was almost nil., there would result an equatorial belt 
 of clouds shielding those regions from a heat that otherwise 
 might destroy all life. 
 
 There are, at the present day, two quite uniform belts of 
 clouds, one north and the other south of the equator. In 
 the conditions I have supposed these belts would probably 
 touch each other, and the light which passed through might 
 well be no greater than that which fell upon circumpolar re- 
 gions. 
 
 This cloud covering reaching from the equator to a con- 
 sideiable distance north and south, would give the condi- 
 tions which the coal flora demanded, warmth, moisture, and a 
 moderate degree of light. Ferns of the tropics are most lux- 
 uriant in moist woods. Equiseta and Lycopods, as well as 
 ferns, like shady and moist places. (Dana, Manual, p. 354). 
 If the cloud covering stopped a considerable distance short 
 of the poles, perhaps in latitude 50 or 60, above that the 
 diminished altitude of the sun would deprive it of the inten- 
 sity which would have rendered it fatal in the tropics, and 
 hence the coal flora was able to flourish there also. 
 
 That which the clouds did for the light, ocean cui rents did 
 for the tropical heat ; they equalized it by carrying it from 
 equatorial to high latitude regions. These currents being, 
 in the absence of changing seasons, absolutely uniform, and 
 the sun giving each day in the year the same amount 
 of heat, the temperature of the polar regions must have been 
 as invariable as that at the equator. 
 
 In view, therefore, of the evidence which geology gives as to 
 the uniform distribution of LIGHT, evidence corroborated by 
 the uniformity of temperature in high or low latitude, it is 
 difficult to avoid the belief that the axis of our planet re- 
 
tained its original inclination of 1=> 30', well into the Plich 
 cene. 
 
 The mild climate of the Tertiary was followed by intense 
 cold. Gradually the previous plants and animals disappeared 
 and an almost earth-wide winter set in. How long it con. 
 tinued there are no means of knowing, but at last it drew to 
 an end, and warmth returned to regions long buried in snow 
 and ice. Once more the world was clothed in verdure ancl 
 adorned with forests. The air, the land and the water 
 again abounded with life. As soon as the records become 
 sufficiently distinct to be read, there is no longer one type of 
 vegetation found from Florida to Spitzbergen. Some species 
 once inhabiting the latter country are yet seen in sub-tropical 
 regions, but in the circumpolar lands are found an artic flora 
 and fauna adapted to extremes of heat and cold as well as 
 to long alternations of light and darkness. . 
 
 These alternations are due to the present large inclination 
 of the earth's axis. There seem to have been none before the 
 Glacial Period ; they occur now, hence I conclude that during 
 the interval was added the needed increase of 22, to which 
 we owe the charming variety of seasons. 
 
 Was there any connection between this movement of the 
 axis and the cold ? Much, I think, as mutual cause and 
 effect, as I shall now seek to show. 
 
 In order to enable the lunar and solar attraction to affect 
 the position of the earth's axis, the earth needed to become 
 prolate, and this means that, if the equatorial diameter re- 
 mained unchanged, the polar regions were elevated 13 i 
 miles, or if the equatorial diameter was so lessened that the 
 volume of the earth was unchanged, the poles were elevated 
 8, 8 miles. In which of these modes the elevation really oc- 
 curred can be as yet only a matter of conjecture. My first 
 impressions which I stated with the reasons in my Cosmology, 
 were that the latter was the true mode, but further reflection 
 has inclined me to the former, as involving less mechanical 
 difficulties and as being possibly explicable by the theory as 
 
 PROG. ro'K. SOC. NAT. SCI. VOL. I. 
 
20 
 
 to its cause which I shall in the course of the evening lay 
 before you. 
 
 It may be said that such a height would produce a press- 
 ure sufficient to crush the hardest granite, and that is true, 
 but the granite would not be affected for the same reason 
 that it is not now, at the same and greater depths beneath 
 the surface. It is compressed and held in place by the later- 
 al pressure. A polar upheaval of this character and extent 
 would readily account for the cold of the early Post-Tertiary. 
 Conversely, the cold thus produced would aid in increasing the 
 required prolateness by heaping up at the poles the oceans as 
 ice-caps. Their own weight even on so moderate a slope 
 would press the ice toward the equator, and give the motion 
 needed to produce the scratches and other traces of glacial 
 action. 
 
 The existence of a cold period following the Tertiary will 
 be denied by few. Traces of glacial action are world-wide, 
 reaching from polar regions to well towards the equator. It 
 is also generally admitted that during the period of cold 
 great circum-polar upheavals occurred, although they do not, 
 and, in the nature of the case, cannot give such evidence as 
 is found in reference to depressions. For these becoming 
 covered with water, received in the soft mud and preserved 
 in the future rocks, the remains of water and other animals 
 of species then living, thus not only proving the downward 
 movement, but even establishing its chronological position. 
 Such records would, of necessity, be absent from elevations. 
 
 An important proof of the reality of such an upward 
 movement is found in the existence of fiords in high latitudes, 
 as in Norway, Greenland, Labrador, Alaska, Patagonia and 
 Chili. These are long, deep bays running far inland, which, 
 evidently, have been eroded by water and ice. Such action 
 could occur only when the land was so much higher than now 
 that running water or ico could erode their bottoms. 
 
 The only real question Ls as to the magnitude of these 
 movements, and of that we are utterly ignorant, and certain- 
 
21 
 
 ly our ignorance is no answer to reasoning based on facts~ 
 which we do know. 
 
 The cold period has excited great inquiry among scientists, 
 and they have diligently sought its cause. Various theories 
 have been proposed to account for it. One of these, viz., 
 circ urn-polar upheavals, we have already considered. Anoth- 
 er which, perhaps, should rather be called a suggestion, is 
 advanced by Prof. Langley, in Dec. number, 1875, of Am. 
 Journ. Science and Art. Referring to the existence of an\ 
 atmosphere about the sun which absorbs a large portion ot 
 the heat from the thermosphere, and which is liable to change 
 of constitution from the varying quantity of gaseous matter 
 ejected into it, he calls attention to the probability of the 
 transmitted heat having been much greater in amount in 
 the remote Geological periods than now. Audi hence there 
 might be, and, indeed, would be, a great variation in thes ; 
 amount of heat received by the earth. A difference of 2L 
 per cent, in transmissive power would, he says, probably 
 raise or lower the temperature 100 F. from the present 
 condition. 
 
 Iii this, as in all other theories, there is a lack of explana- 
 tion of the equability of temperature, and a total ignoring 
 of the equability of light distribution, indicated by uniform- 
 ity of plant life, which is so incomprehensible in connection 
 with the long polar nights and days which must have existed 
 at that time if, as scientists suppose, the axis was inclined 
 231. Hence if, in some way, the change from warm to cold 
 and from cold to present warmth, could be accounted for, 
 the problem would be but half solved. 
 
 Mr. Croll has proposed another theory which I shall discuss 
 somewhat at length, as it now occupies a very prominent 
 position, and has been- accepted by many scientists as offer- 
 ing a true explanation of the cold of the Glacial Period, and 
 as it has more or less bearing upon the extent and epoch of 
 the primordial inclination of the earth's axis. 
 
 In hia " Climate and Time," Mr, Croll endeavors to show 
 
22 
 
 that the cold of the glacial epoch, was not due to changes 
 in the elevation of the land, but, indirectly, to variations in 
 the eccentricity of the earth's orbit and in its obliquity, com- 
 bined with the precession of the equinoxes. I say "indi- 
 rectly," because he admits that no increase of heat or cold 
 could come from astronomical conditions alone. Indeed, he 
 styles 'the assertion " absurd." This certainly differs very 
 widely from the view generally taken of his theory, and it 
 enables him to avoid the force of most of the arguments thus 
 far brought against it. 
 
 It is to be observed that he too ignores the uniform distri- 
 bution of light, as well as the difficulty of keeping uniformi- 
 ty of temperature, in latitudes where four months of uninter- 
 rupted sunshine were followed by darkness of equal du- 
 ration. 
 
 The question of a possible change in the direction of the 
 earth's axis is not considered by him any farther than to 
 state that " it has been shown by Professor Airy, Sir Wm. 
 Thomson, and others, that the earth's equatorial protuber- 
 ance is so great that no geological change on its surface 
 could ever possibly alter the position ot the axis of rotation 
 to an extent that could at all sensibly affect climate." 
 
 But if the earth, from any cause, became temporarily a 
 true sphere, and then the contents of the oceans were piled 
 as ice about the poles, the case would be very different. 
 The latitudes indeed would not vary, but the direction of 
 the axis in space would undergo a change due to the at- 
 traction of the moon and sun.* 
 
 Mr. CrolFs theory assumes, without inquiry the present 
 axial inclination to have been attained before the geological 
 
 * The possibility of such a polar upheaval as appears to me to have occurred 
 seems never to have been considered. Newton touches upon it in the " Prin- 
 cipia" so far as to assert that if the earth were a sphere, and a mass were laid 
 upon it at either pole, it would produce a recession df the equinoxes; and 
 tbat implies the movement of the axis towards the ecliptic in ever-widening 
 spiral until equilibrium was restored. 
 
 The effect of centrifugal forces generated by masses placed between the 
 poles and the equator is curious, and is related in a very interesting 1 manner 
 to the present distribution of land and water; I have discussed the prince 
 pies in my Cosm*>ogry,^-J^iraf7es of To-Pay, page 218. 
 
23 
 
 record begins. It also requires not one glacial period, but 
 many. 
 
 So important does he deem this last that he styles it " the 
 grand crucial test of the truth of his theory," (p. 237.) 
 
 This has induced a careful study of the formations older 
 than the Post-Tertiary which, in his opinion, establishes the 
 existence of glacial action even before the carboniferous age. 
 The proof, as stated by him, consists in the existence of con- 
 glomerates, having the appearance of glacial debris, but in 
 nearly all cases destitute of the characteristic scratches. Ad- 
 mitting, however, that these formations are due to ice-action, 
 I notice two circumstances that have, as it seems to me, a 
 most important bearing upon their proper explanation. The 
 first is the scant and limited nature of these remains. There 
 is nothing whatever, approximating to the world-wide traces 
 of that ice-period which followed the Tertiary. Beds of con- 
 glomerate of those older periods have been found in Scot- 
 land, together with some quite large boulders, some near 
 Lake Superior, some in Nova Scotia, a few in Ohio in a 
 seam of coal, some in Australia, which Mr. Selwyn was in- 
 clined to think were probably of glacial origin. Mr. Bland- 
 ford thinks he found evidence of ice action in India. Prof. 
 Ramsay has suggested that similar accumulations in Ger- 
 many, betray like traces of old ice action. There are some 
 in England, and some in Switzerland. But these are mere 
 spots compared with the wide spread traces left by the great 
 Glaciers that followed the Tertiary. Their remains cover 
 more than half the land of the globe, reaching from the poles 
 to latitude 35 deg. or lower. 
 
 M. Geikie, in his "Great Ice Age," supports Mr. CrolPs 
 theory, and from his appendix I have taken the substance of 
 the last paragraph as to the evidence of early glacial action.. 
 
 The second important circumstance is the kind and distri- 
 bution df plant lifej which seems to me utterly inconsistent 
 
 * These may have been dropped from the rootSdf floating trees, as are the masses 
 of basaltic rocks oscasionnlly found, upon the coral atolls 0f the Pacifio. 
 Mnti. p, 3170 
 
with this theory. That I may do no injustice I quote from 
 Mr. Geikie: 
 
 "Now if we were to judge only from their organic con- 
 tents, we should be forced to admit that none of these for- 
 mations down to the Miocene, afford any trace . whatever of 
 cold or glacial conditions. So likewise the appearance of ice- 
 transported blocks in the Miocene, is a sore puzzle. The 
 fossils of this formation speak to us of tropical and sub- 
 tropical climates having prevailed in Central Europe. Nay 
 more, Miocene deposits have been detected in high arctic 
 latitudes. Species of Sequoia, Conifer, Poplar, Willow, Oak, 
 Walnut, Plum, Andromeda, Daphnogene, and several other 
 evergreens grew during Miocene times in North Greenland ! 
 Even in Spitzbergen, abundant traces of the same kind of 
 vegetation have been preserved." 
 
 Here we have glacial deposits and tropical vegetation, the 
 glacial deposits "in Italy," and the tropical vegetation in 
 Spitzbergen ! Mr. Geikie gives a yet more remarkable 
 instance from Prof. Dawson, who describes " a gigantic esker, 
 on which were deposited large travelled bowlders." This 
 was found on one side of a coal region, where the character- 
 istic plants of that formation were growing. 
 
 Well does Mr. Geikie, with his view of the causes of the 
 cold epochs, say that " Geologists are puzzled over these 
 facts ! " Mr. Croll gets along with them by the assumption 
 that several glacial periods occurred in alternation with 
 warm ones during the progress of the same formation. That, 
 for example, during the coal age, there were 10,000 years of 
 warm climate, during which a seam of coal was deposited ; 
 that this was followed by 10,000 years of cold, and then 
 10,000 years more of warmth, and another seam ; and thus 
 for an unknown number of alternations : and so during the 
 other Ages 
 
 These changes from hot to cold and from cold to hot, how- 
 ever, admitting their occurrence, being dependent upon astro- 
 nomical causey could not have been sharp, but the maxi- 
 
inum heat must liavo grown less very slowly, and there must 
 have been an intermediate condition of long duration gradu- 
 ally hardening into the cold or glacial ; and there is, as far 
 as I see, no reason to doubt the tolerably equal duration of 
 each of these periods. In a cycle of 22,000 years there must 
 have been one warm period, one temperate, one cold, and a 
 second temperate, each continuing about 5,500 years. 
 
 If there were no animals fitted to live in any epoch but 
 the warmest, there was exhibited the remarkable, and I may 
 say, inconceivable spectacle of a region covering more than 
 one-half of the entire land surface which was destitute of or- 
 ganic life for nearly three-quarters of each great cycle of 
 22,000 years, a region too which, in the remaining quarter, 
 abounded in life, and which, at the present day, has an ap- 
 propriate flora and fauna; the latter surpassing that of 
 any other portion of the globe in the multitude of individu- 
 als which compose it. 
 
 If, on the other hand, there were at that time animals and 
 plants fitted for a rigorous climate, they must have perished 
 when the heat of Florida reached Spitzbergen, and probably 
 as far beyond as land extended towards the pole. 
 
 But granting that, by some happy although inexplicable 
 circumstance, they lived through the, to them, fiery heat of 
 the cosmic summer, when, in the cycle of time, the cosmic 
 winter came on, and snow and ice formed a covering too deep 
 to permit the land animals to reach the scanty vegetation or 
 to supply their needs from the seas, they must have perished 
 where they were, or have migrated to more genial climes. 
 As the snow gradually edged its way down, many gener- 
 ations lived and died in each successive belt. They must 
 have spent centuries in each new locality ; and certainly the 
 carboniferous swamps would have had their share of arctic 
 denizens. The soft mud which hardened into the shales 
 would have preserved their remains -as readily as those 
 which are now found there. Then, as the wave swept on, 
 and after thousands of years returned, and again the polar 
 
fauna and flora paused on their northward journey, 
 all the centuries of that slowly-returning spring, there ought, 
 by every reason, to have been left in the mud of those 
 swamps another layer of their remains. Yet not a plant nor 
 an animal of the land or water, proper to a cold climate, was 
 left to mark their once abundance. Remember, the polar 
 fauna and flora must have occupied the ground as long as 
 the coal plants, and note the overwhelming abundance of 
 the latter and the total absence of the former. The thing 
 seems impossible. 
 
 It is easy to explain, as Mr. Croll does, the absence of any 
 great amount of glacial surface marks, on the supposition 
 that subsequent glacial or atmospheric action has obliterated 
 them; but such agencies could have no effect upon those 
 other records, which ought, if the early cold periods ever ex- 
 isted, to have been securely hidden within the strata them- 
 selves. 
 
 Again ; the condition of the beds of coal forbids the pos- 
 sibility of such a gradual lowering of temperature. If Mr. 
 CrolFs theory be true, the heat must have been decidedly 
 less at the beginning of the time of forming a coal bed and 
 must have increased until the middle and then diminished 
 until coal plant-life again became impossible. The plants at 
 first would barely live, and the fossils should afford only a 
 few scant species of the more hardy kinds, and then those 
 less hardy with increase of numbers and greater luxuriance 
 of growth. As the summers grew cooler again, these middle 
 species would have died out and a flora, such as marked the 
 beginning, would alone remain. But the fossils give no such 
 story as this. On the contrary, they tell of a " warm, moist, 
 equable climate" and give not a sign of any such changes. 
 The only argument is based on the alternation with the 
 coal beds of layers of non-fossiliferous materials, some of 
 which Mr. Croll thinks are due to glacial action. Granting 
 that he is correct as to their cause, which is by no 
 means certain, they are consistent with the absence of any 
 
2?* 
 
 such glacial periods as he requires, if we admit the existence 
 of local glaciers during these early periods, a supposition no 
 more contradicted by the admitted warmth of those times, 
 than a like cause forbids them to-day in the Himalayas and 
 Andes. That would readily account for the limited extent 
 of the glacier traces, and for the prevalence in the same 
 period of tropical plants, often in close proximity. The in- 
 stance cited from Dawsou, is remarkably in point, and gives 
 exactly the conditions we should expect from the ice coming 
 from higher land and wasting away at the side of a low car- 
 boniferous tract, and seems inexplicable on any other theory. 
 Moreover, if any of those glaciers reached down into the 
 seas or lakes of those periods, they might float off and thus 
 carry to a distance blocks of stone. 
 
 To this it may be said that no sufficient mountains then 
 existed, and I am aware that it is generally thought that the 
 surface of the early world was as uniform as its climate. 
 But what man can believe that in ages when, as in the Alle- 
 ghanies, depressions of 40,000 feet were made, there were no 
 corresponding elevations ? The simple fact that these im- 
 mense depressions were filled with debris brought from some- 
 where, proves the existence of the upheavals.'-' 
 
 This supposition, if sustained, disposes of Mr. CrolPs as- 
 sumption that strata without fossils, lying between fossilifer- 
 ous ones, are due to a general glacial period. 
 
 There is no question as to the existence of a warm climate 
 reaching almost to the poles, but all the evidence which he 
 brings to prove it, has no special bearing on his theory, since 
 the real question is whether the admittedly warm period was 
 continuous, or whether it was interrupted by periods of semi- 
 telluric cold, and the latter the evidence does not sustain. 
 
 *The average thickness of the stratified rocks is probably not much less than In 
 Europe, which must be 25,000 I'eet and more. (See Prof. Dana's Manual, p. 145.) 
 The most of this was formed before the Mesozoic. It is difficult to see where all 
 this detritus came from without immense upheavals. Prof. Ramsey is of the 
 opinion that in pre-Miocene times, the Alps were probably higher than now. He 
 tlnds thia " amply demonstrated by the enormous thickness of fresh water and 
 marine deposits of the Miocene Age now spread over Switzerland," Pop. Science 
 Mo., Oct. 1875. 
 
 PROG. FO'K. SOC. NAT. SCI. VOL. I. 
 
28 
 
 I have spoken of the Carboniferous period only, but the 
 same reasoning applies to the other periods down to the 
 close of the Tertiary. 
 
 In some of the most recent deposits long after the Glacial 
 Period, there are found mingled together the bones of ani- 
 mals, of "which some, as the musk-ox or reindeer, seem to 
 have been inhabitants of a cold country, while others, as the 
 hyena and tiger, appear to have required a warm region. 
 This is exactly what we should expect in case those regions 
 had been alternately warm and cold. The presence, there- 
 fore, of arctic and temperate, or sub-tropical animals in the 
 recent deposits is proof of a recent alternation of climate 
 from some cause, while their absence from the earlier forma- 
 tions is evidence that no such alternations then occurred. 
 
 The fact that the bones are mingled is to me incompre- 
 hensible, if the animals were really wide apart in time as for 
 instance 6,000 to 10,000 years. For, certainly, if a layer of 
 arctic animals and earth was made and then left alone for 
 thousands of years until astronomical causes could have 
 time to bring the needed warm climate, the stratum would 
 have become so compacted that no commingling would after- 
 wards be possible. 
 
 In regard to this recent or Reindeer Period, I note two 
 circumstances which seem to me of great importance in their 
 bearing upon Mr. Croll's theory. 
 
 First, It lacks the telluric character to be expected if it 
 was due to changes in the position of the earth and the 
 eccentricity of its orbit. A cold period so produced should 
 affect the whole northern hemisphere, but if it occurred at all 
 on this continent it was scarcely arctic in character, indeed, it 
 can hardly be said to have been made out at all. 
 
 Second, The cold came on " suddenly as if in a night," as 
 Prof. Dana says. Such an abrupt change could in no way 
 be due to a movement in a cycle requiring 22,000 yean-, for 
 for its completion. 
 
 On the other hand, it oilers the characteristics of a climate 
 
made colder by some comparatively sudden surface change 
 affecting the elevation of the land or the direction of ocean 
 currents. 
 
 Such a period so produced casts light upon the possibility 
 of early local glaciers. 
 
 In regard to these earlier periods, I am glad to find my 
 conclusions in harmony with so able a master in this Science 
 of Geology as Sir Charles Lyell, who says in support of his 
 belief in the " absence of re-current Glacial Epochs in the 
 earlier formations. The continuity of forms, particularly in 
 the class of reptiles from the Carboniferous to the Cretaceous, 
 is opposed to the intercalations of glacial epochs correspond- 
 ing in importance to that of the Post-Pliocene." 
 
 Mr. Geikie devotes a very large part of his book to show- 
 ing that in Scotland between layers of the till, or what we 
 here call hard-pan, are other layers indicating a wanner 
 climate. And this, I think, he proves, but it is local glaciers 
 that he is everywhere dealing with, and those wholly Post- 
 Pliocene, for they contained remains of Bos primigenius, 
 Irish Elk, or Deer, Reindeer, Mammoth, &c. The direction of 
 the scratches of the marine deposits shows local action- 
 " What positive evidence we have points rather to the exist- 
 ence of local glaciers in the higher valley to 'moderate sum- 
 mers and severe winters during such inter-glacial periods as 
 we have any certain records of." This is on page 181 of his 
 Great Ice Age, but similar evidence is found almost on every 
 page. The same remarks apply to the glacial traces and 
 warm intervals found in Switzerland. The explanation is in 
 local upheavals and subsequent depressions, examples of 
 which abound in the past. 
 
 Mr. Croll attaches great importance to ocean currents as 
 modifying climate and devotes several chapters to showing 
 that they are due to the winds. 
 
 This is a physical question of great interest, but uotjrital 
 to the one which we are considering, since he may be right 
 as to the cause of these mighty streams and yet mistaken as 
 
30 
 
 the theory of climatic changes. I shall therefore dismiss 
 it without further remark. 
 
 The one thing, however, which Mr. Croll must establish or 
 abandon the ground, is the occurrence of many real, conti- 
 nental, or rather semi-telluric, glacial periods, alternating 
 with warm ones. Hence, I have directed your attention to 
 iiri examination of the evidence which may be drawn from 
 the presence or absence of the fossils which w r ould character- 
 ize such climatic vicissitudes. 
 
 It seems to me that the Geological records fail to establish 
 the alternations of cold with the acknowledged warm epochs 
 But if the evidence had proved their existence, still Mr. 
 Croll's theory would utterly fail to account for the remarka- 
 ble fact that in the warm intervals always, there was uni- 
 formity of plant life from Spitsbergen to Florida. If telluric 
 glaciers really existed in the Carboniferous and other early 
 ages, they may have been due to telluric upheavals of a 
 height sufficient to make the cold, but not to affect the posi- 
 tion of the earth's axis. We find no evidence of that until 
 after the Pliocene. 
 
 There yet remain two problems whose discussion is needed 
 to complete what I desire to say upon this subject. 
 
 The first is a question in mechanics. Certain known ef- 
 fects are given, and a cause is suggested as accounting for 
 them. Do the effects correspond to the assumed cause? 
 This I may illustrate by a homely example. 
 
 A ship is seen moving against the wind and current. To 
 one who inquires the cause, a bystander says, " It is a man 
 in the vessel turning a crank which drives a propeller screw." 
 The listener, knowing the great size of the vessel, and the 
 power of the wind and current, would at once pronounce the 
 #ause inadequate, or in other words, the known effect to be 
 too large for the cause assigned. On the other hand it is 
 easy to imagine cases, where the effect should not be large 
 enough. 
 
 This is the kind of problem which we liara now to solve, 
 .and it may be thus .stated, 
 
The moon, on the supposition that its orbit was once in 
 the plane of the earth's equator, and that they both were 
 then inclined to the ecliptic only U cleg., has been so moved 
 that its orbit is now inclined 5 cleg., 9 mm. This would re- 
 quire an actual uplifting of the moon of at least 3 deg. 39 
 min., or 13,200 miles. 
 
 Now calling the earth's radius and mass each 1, the 
 distance to the moon will be GO and its mass about 1-90. It 
 is easy to show that any polar force on the earth will, by the 
 laws of resolution of forces, lift the moon from the ecliptic 
 with a force 1-60 as great as that which tends to draw it di- 
 rectly towards the earth, or the earth towards the moon ; 
 and since the hitter's mass is only 1-90 of the earth's, it 
 would be moved 90 times as lar: or combining the two 
 ratios, the actual movement of the m_>on will be 90-GO, or 11 
 times, that of the earth.* 
 
 This force, then, would move the earth 2-3 of 13,200 miles, 
 which is 8,800 ; but, being applied at the terrestrial pole as 
 a tangent, it tends also to make it (the pole) rotate towards 
 the ecliptic, and ought to cause it to pass through 22,000 
 miles, almost a circumference. But, in fact, the pole, in 
 going from 11 to 231, travels only 1,320 miles; and not all 
 of this, even, is due to the moon, for there is the effect pro- 
 duced by the sun, of which I have said nothing. 
 
 The resulting motion seems greatly less than it ought to 
 be. Is it really so ? And shall we be obliged to discard the 
 supposed cause of this movement and seek another ? If not 
 what has become of the excess of force ? 
 
 If on exhaustive examination, it shall appear, that the ef- 
 fects are in fact too small and that the excess cannot be ac- 
 counted for, then we are on the wrong track and must begin 
 anew. 
 
 To seek to answer, therefore, this question is our next 
 business. 
 
 *As there is no attempt here to solve these questions numerically, I have used 
 for the ratios only convenient approximations, 
 
32 
 
 Here comes in an interesting and curious principle, viz., 
 the persistence or fixity of the plane of rotation. A body re- 
 volving on an axis can be made to change the direction of its 
 motion, but only at the expense of force employed in over- 
 coming that persistence. We see this principle in that modi- 
 fication of the Gyroscope, called the Mechanical Paradox. 
 This consists of a disk revolving on pivots within a ring, 
 having on the line of prolongation of its axis on one side, a 
 bar or spur with a smooth notch beneath, to receive the hard, 
 smooth point of an upright support. If now the disk is 
 made to rotate rapidly, and the bar be set upon the sup- 
 porting point, the whole begins to revolve slowly around the 
 point and to slowly fall. Gravity acts freely upon the un- 
 supported end, and yet such is the persistence of the plane 
 of rotation, that it falls only an inch or two in many seconds. 
 Almost the entire force of gravity is expended in moving it, 
 and only the merest fraction, in making the ring actually fall. 
 If its descent is only 5 inches in 10 seconds, then all but 
 1-3840 of gravity is thus consumed. The more slowly, how- 
 ever, the disk rotates, the more rapidly it falls, and the less 
 is the proportion expended in moving the fixed plane. Now 
 in this case, the earth may be regarded as a rotating disk, 
 and the lunar attraction upon the circumpolar upheaval, as 
 the attraction of gravitation tending to pull the disk down, 
 and the effect produced is the amount of fall; hence the 
 greater part of the force should be expended in changing the 
 plane cf rotation, and only a small proportion in actual 
 movement of the earth. 
 
 As the attraction of the terrestrial polar upheaval had no 
 tendency to change the plane of the moon's rotation, its 
 whole force was expended in lifting the moon, so to speak, 
 from the ecliptic. Hence if the hypothesis under consider- 
 ation is true, the actual distance of the moon from its normal 
 position, ought to be much greater than that through which 
 the pole of the earth has moved, and observation shows that 
 such is the case. 
 
33 
 
 It would be very desirable to calculate what should be 
 upon this theory, the ratio of the two movements. 
 
 This is a problem of great difficulty, but not, I think, in- 
 solvable. For the present we must rest satisfied with 
 showing that the actual movement of the moon ought to 
 have been much greater than that of the earth, a result that 
 fully agrees with the statement already made, that the moon 
 has moved 13,200 miles, while the pole of our earth had 
 traveled only 1,320. 
 
 The other problem of which I spoke pertains to the reason 
 of these upheavals ; what caused them ? 
 
 My inability to answer this question, would not effect the 
 fact of their occurrence, but only leave me in the presence of 
 a great physical phenomenon of whose cause I am ignorant ; 
 a position in which every scientist finds himself in reference 
 to very many of the phenomena about him. 
 
 To explain these movements there must be found a force 
 sufficient to elevate simultaneously the circumpolar regions 
 of both hemispheres, covering, as they do, many millions of 
 square miles, a force able to do this, not spasmodically, but 
 so slowly and uniformly as to produce little contortion or dis- 
 placement of the strata. Moreover, a true solution must 
 account for the fact that these upheavals were not permanent, 
 and that after a time, probably a very long time, they sank 
 back again. 
 
 A little reflection will show that this is a problem of great 
 difficulty. I have often attempted it, and have as often been 
 baffled ; nor am I now prepared to assert that I have solved 
 it. I can only say that in certain other physical phenomena, 
 I think 1 see a glimmer of light that may lead out of the 
 darkness which at present surrounds the subject. 
 
 It will be necessary to go back to a period when the globe 
 was a ball of molten lava a fluid and subject to the laws of 
 fluids. It is evident that in such a compound mass, those 
 substances which solidified first and were of least specific 
 gravity would float on the surface as slag on melted iron. It 
 
84 
 
 is well known that the present crust is only about 2-5 as 
 heavy as the interior and that it is composed of the most 
 refractory substances. Hence, for a time at least, there was 
 a floating crust, like ice on a pond.* By the laws of motion 
 any such floating crust tended towards the equator, and 
 hence, we are justified in concluding that the crust was thick- 
 est in these parts, and for precisely the same reason thin- 
 nest at the poles. After a certain thickness of crust, probably 
 some hundreds of miles, had been formed, we may suppose 
 the supply of like materials exhausted, and the globe to 
 have gone on cooling without much apparent change until, 
 after a sufficient tinio, the interior approached the tempera- 
 ture at which a portion of it began to grow more consistent 
 and, it may be, to reach the solid condition ; a supposition 
 strongly corroborated by certain astronomical observations in 
 reference to the movements of the moon, which appear to 
 indicate that the interior is not now a fluid. 
 
 It is well known that at least one fluid contracts with a 
 decrease of temperature to a certain point, and then, with 
 further decrease actually expands, until it becomes solid, 
 after which it again shrinks as the temperature falls. A sim- 
 ilar increase in bulk is said to occur where certain metals 
 assume the solid form. Plaster of Paris expands at time of 
 *' setting." A change in the dimensions of some bodies takes 
 place when an electric current passes around them. It seems 
 highly probable that expansion takes place when melted 
 substances pass into a crystaline form. The force put forth 
 at such times is immeasurable. 
 
 Now apply this to the earth. In the process of cooling, 
 its interior had arrived, we will suppose about the close of 
 the Tertiary, at a temperature when like water at 40, it be- 
 gan to expand with further cooling. This expansion pro- 
 duced a slow and equable, and practically irresistible pres- 
 sure upon the surrounding crust, which had to yield at the 
 
 * If it is true true th'it granite shrinks 8 per cent, i a solidifyingf.it would still 
 be much lighter than the average l lava " wuich made up the earth. 
 
85 
 
 weakest points, and these were the polar regions because the 
 crust was there thinnest and flattest. Consequently those 
 parts were pushed outward, that is upwards, to an extent 
 limited only by the duration of the force, or the cohesive 
 power of the crust. 
 
 The only other thing that could occur, was to break 
 through the crust, but when the great extent of the flattened 
 portions (50,000,000 square miles each) is considered, it will 
 be seen that flexure would be much easier than rupture. 
 For, if the crust were 300 miles thick, its flexibility 
 would be represented by that of an iron bar 80 feet long and 
 1 foot square, and the necessary flexure by a drooping at the 
 centre of less than 1 inch. Such a bar supported at each 
 end would bend by its own weight many times as far. 
 
 Nor was the expansion needed to raise the polar regions to 
 the surface of the circumscribed sphere proportionately 
 very great, being only 4-1000 of the bulk of the fluid con- 
 tents. Mercury expands 1-10,000 for every degree of heat 
 added ; if the mass in its cooling obeyed the same law, it 
 needed only to lose 40 of heat, a very small amount indeed 
 in reference to its high temperature. 
 
 Such an expansion would give the kind of force required. 
 It would lift the crust with a slow and equable motion, and 
 hence would produce little disturbance in the order or incli- 
 nation of the strata. The surface would be raised in lines 
 so long that their flexure would be imperceptible, and there 
 would be required only a slight elongation in a polarward 
 direction. Its effects would reach nearly to the equator, and 
 its pressure, being by the laws of hydrostatics equal in all 
 directions, would push out one pole with the same force and 
 at the same time as the other. 
 
 Although such a movement would change the earth's sur- 
 face to that of a true sphere, yet owing to the centrifugal 
 force, the practical effect would be the same as raising an 
 immense mountain to the same height, or more accurately a 
 plateau sloping on every side towards the equator. Such an 
 
 PEOC. PO'K. SOC. NAT. SGI. VOL. I. 
 
36- 
 
 elevation would produce the most intense cold. As it gradu- 
 ally rose, the water, in a great part at least, flowed toward 
 the equator and would have accumulated there but for a 
 counteracting force. It is well known that the air takes up 
 water at any temperature, as long as its capacity is not satis- 
 fied. That which rose from the equatorial seas, passed 
 towards the poles and there deposited its moisture, not 
 as rain, but as ice and snow, and then returned for a 
 new supply, just as in the well known philosophical toy 
 called the Cryophorus, the water is transferred from the 
 warm to the cold bulb and there frozen, until all is exhausted. 
 How complete the transference was, depended only on the 
 duration of the process and the intensity of the cold, and not 
 as has been said upon any extraordinary heat to produce an 
 unusual amount of evaporation.* 
 
 The earth having become nearly or quite spherical by the 
 internal expansion, the waters of the ocean piled as ice in 
 circumpolar regions, gave the extra-spherical masses required, 
 which, by the help of solar and lunar attraction, produced 
 the increase of the axial inclination of the earth as well as 
 the change in the position of the moon's orbit. 
 
 The cause of these upheavals, so far as it depended upon 
 the internal expansion which we have been considering, 
 reached a limit as soon as the solidifying process was com- 
 pleted on the part of those portions of the fluid contents of 
 the earth which congeal at such a high temperature. After 
 this, farther cooling produced contraction as in other solids, 
 for even ice shrinks by farther increments of cold. 
 
 A reportf on casting broaza guns made to the Secretary of 
 
 *NOTK. It has been said that a low equatorial temperature would not give 
 moisture enough to form the Glaciers. To test this, I filled a tin vessel with salt 
 and snow and placed it out of doors where the thermometer stood at 31. In about 
 twenty minutes the sides were covered with Irozen moisture to such a depth that 
 I could easily scrape it off in little pellets, In this case after a time, the process 
 would have ceased on account of the non-conducting power of the rime. But 
 if it had heen removed the process would have continued for any length 
 of time I chose to keep it up. So in polar regions. The frozen moisture was at 
 once deposited on the ground and there remained as ice, while the air went back 
 fora fresh supply. The amount and rapidity of the transference depended upon 
 the difference between the polar and the equatorial temperature. 
 
 t "Reports of Experiments on the strength and other properties of Metals for 
 Cannon." 
 
37 
 
 War, 1856, gives some observations which are interesting in 
 this connection (page 295.) 
 
 In casting a large gun the mould was poured even full. 
 At first the surface sank down II inches below the top. 
 Soon after, it presented an appearance as of ebulition, as of 
 gases escaping and expelling the more fluid portions of tho 
 alloy, which rose and overflowed the mould, and when it be- 
 came solid it projected considerably. After it became solid 
 it was at first of course very hot, and while becoming cold it 
 must have shrunk as any other metal. Unfortunately for 
 our purpose no account is given of the last shrinkage. 
 Probably it was the same as in case of any other piece of 
 bronze. 
 
 In this instance there was first a shrinkage, then an ex- 
 pansion, then a cessation or standing still, and lastly a 
 second shrinkage, all under the influence of a falling temper- 
 ature. 
 
 We may suppose then that the farther cooling of which I 
 have spoken, went on, which after a time resulted in a 
 shrinkage, causing the weaker portions of the crust to fall in. 
 These were the polar regions since they were the thinnest, 
 and the equatorial belt was pressed outward by the 
 centrifugal force. I have not thought it necessary to con- 
 sider the effect of the arch, for on so long an arc, the most 
 perfect homogeneity and regularity would be necessary, and 
 these would be destroyed by the slightest variation. In 
 short, the polar regions would offer the least resistance to a 
 movement in either direction. 
 
 If under the enormous strain generated by the centrifugal 
 foice while the polar diameter was elongated, the equatorial 
 belt at last yielded so much as to be lengthened 1-16 of one 
 per cent., the additional space thus gained would take up the 
 entire amount needed to change the sphere to its present 
 form. 
 
 I see no reason why similar alternate expansions and 
 contractions might not have occurred at various epochs in the 
 
world's history, for the contents of the earth mast be com- 
 pounded of many substances, each having its own point of 
 congelation, and it is quite possible that as the temperature 
 fell, the time of reaching each one of these may have been 
 marked by some such movement, either of expansion or con- 
 traction. Possibly this action on a limited area may account 
 for some of the local movements which are so perplexing. 
 
 Whatever may be thought of this as the explanation of a 
 hitherto unsolved problem, I think I may safely, say, it is 
 based upon facts and possibilities, and violates no law. I 
 offer it for your consideration. 
 
 In conclusion I will briefly sum up the facts stated and 
 the deductions which I have drawn from them. 
 
 The earth's axis at the moment of separation from the 
 lunar, belt was inclined not more than 1 1 deg, and is now in, 
 clined 231 deg. ; hence at some time an increase of obliquity 
 occurred 
 
 Astronomy, or Celestial Mechanics, gives no indication as 
 to the time of this increase. It tells of possible conditions, 
 arising from solar and lunar attraction upon circumpolar up- 
 heavals, and manifested in the change of the moon's orbital 
 inclination from 1 30 / to 5 9', but gives no intimation as to 
 the epoch at which the movement actually occurred. We 
 turn then to Geology, and this, as I read it, is the story ifc 
 tells. 
 
 At the dawn of life, as the land was just beginning to ap- 
 pear, a tropical warmth extended to the poles. This was 
 due, in part, to the limited extent of land surface, in part, to 
 ocean currents, but, in a much greater degree, to the 
 presence of carbonic acid, and, perhaps, other impurities in 
 the atmosphere, which, while freely permitting solar heat to 
 reach the earth, acted as a barrier to its escape. 
 
 A free exchange of aerial and ocean currents, and, perhaps, 
 a persistent belt of equatorial clouds, equalized the tempera- 
 ture of what are now torrid and arctic regions, and aided iu 
 producing uniformity of biological development* 
 
As the ages passed, the carbonic acid, by various chemical 
 processes, was taken from the air and stored away as coal or as 
 carbonates. While this was going on the warm covering grew 
 thinner, and more heat was radiated back and lost in space I 
 and, although uniformity and equability of climate long re- 
 mained, yet the earth's temperature was slowly falling. 
 
 The flora of the Miocene was one demanding days ami 
 nights of equal (i. e., not polar,) length, yet indicating a 
 climate cooler than, for instance, in the Cretaceous. In 
 short, the thermal lines were falling towards the equator. 
 
 The earth's surface during this long period was under- 
 going great changes. There were vast depressions and corre- 
 sponding elevations, rising sometimes into mountains perhaps 
 higher than any now existing. On some were local glaciers, 
 forming moraines and depositing their debris in the warmer 
 valleys. 
 
 The same agencies which, at later periods, obliterated 
 other mountains may have worn those away ; or, like de- 
 pressing forces, may have brought them down. Some such 
 movements were probably the cause of the limited, earlier, 
 glacier-like traces, found in various places. 
 
 But all along, in every place where there are fossils to tell 
 the story of climatic condition, there is a lack of proof of sea- 
 sonal vicissitudes, or polar nights of months' duration. This 
 I understand to be the evidence of plant-life and animal-life 
 from the dawn of existence to near the close of the Tertiary > 
 and from it I conclude that thus far the axis of our earth 
 was still nearly perpendicular to the ecliptic. 
 
 How long the Glacial period lasted is unknown, but at 
 last it drew towards its close, and plant-life revived. The 
 geological record after this is far inferior in sharpness of defi- 
 nition to that which preceded it, but as soon as the story can 
 be read with certainty, it tells of zones of climate, alter- 
 nations of seasons and long polar nights and days. The mo- 
 notonous uniformity of the past is gone forever. Admitting 
 the uniformity of law, that like causes produced like effects 
 
as well in the remote past, as in the present, I see no way to 
 escape the conclusion that during this period of circumpolar 
 elevations, the axis of "our earth attained its present ob- 
 liquity. 
 
 However difficult it may be to believe it, or even to con- 
 ceive of it, the fact remains that in some way the earth has 
 attained its present position, and nothing is gained by re- 
 ferring the movement to some unknown and more remote 
 period when "somehow it got tilted to one side," and we 
 should remember, too, that no more power was needed to 
 change its inclination after it had existed through the geo- 
 logical ages, than before. 
 
 I have elsewhere (see note at the end of this Essay) shown 
 that this great event could not have been due to magnetic 
 forces, as some have thought, nor to collision with meteors, 
 as lately suggested, nor to centrifugal forces, as at one time 
 asserted ; and that while it might have been due to a mira- 
 cle, yet such an interference is highly improbable, because 
 every member of the solar system has its axis more or less 
 inclined, not excepting the Sun, where nights are impossible, 
 and seasons, the supposed object of such a miracle, are 
 inconceivable. 
 
 Being thus compelled to seek some other cause, I ex- 
 amined into the effects which could be produced by the at- 
 traction of the Sun and Moon on circumpolar upheavals, and 
 found here a force that could compel the Axis to become 
 more oblique. I then went over the records of plant and ani- 
 mal life, and found a condition and distribution that seemed 
 to me inexplicable unless the axis had thus far retained its 
 perpendicularity. I found this period f uniformity followed 
 by a time of groat cold and enormous circumpolar upheavals, 
 and after the cold disappeared the uniformity so marked be- 
 fore, was gone forever. I concluded then that in the interval 
 was the epoch of this great event. 
 
 As far as I can sec, the only objection to this conclusion is 
 the .greatness of the upheavals required. I submit, however, 
 
41 
 
 that this objection is not fatal, since absolutely nothing is 
 known of the extent of these movements, nor of the nature 
 or limits of the force producing them. 
 
 Besides, the greatness of which we speak is only relative 
 to man. Compared with the globe itself they sink into insig- 
 nificance, the height being scarcely one-third of one per cent, 
 of the radius, or one-fiftieth of an inch on a thirteen-inch 
 globe, an amount which no unaided eye could perceive. 
 
 The objection which arises from the inequality between the 
 movements of the moon and of the pole, is not only accounted 
 for, but shown to be necessary to the truth of the theory. 
 
 Omitting all reference to the supposed cause of the polar 
 upheavals, since its truth or falsity does not effect the argu- 
 ment, the condition of our system, the laws of motion and the 
 record of Geology are such that I feel compelled to believe 
 that we have arrived at two great and important facts in the 
 history of our world; 1st, that from the moment of separation 
 from the lunar belt until well towards the close of the Tertiary, 
 its axis was nearly perpendicular, its obliquity not exceeding 
 11 ; and, 2nd, that the increase to 23 \ occurred during that 
 period of cold which followed the Pliocene and which ia 
 usually known as the Glacial Period. 
 
 NOTE 1. In the Essay upon Cosmology which forms Part III of the Miracle of 
 To-day, I have treated quite fully of several points to which I have only alluded in 
 this article. The one is in some respects the complement of theother. 
 
 NOTE 2. The early uniformity ef climate as indicated by the fossils is admitted 
 by all modern Geologists. For the convenience of those who have not looked into 
 the matter I add a tew references to Prof. Dana's Manual of Geology, 1874, " No 
 Zones of Climate," see p. 181, 209. 253/289, Xi2, 452, 480. 
 
 NOTE 3. My attention nas been called to the allefffd discovery in Siberia of vines 
 bearing fine grapes within the Arctic circle, and the question has been asked, how 
 such a fact affects my theory. I reply that it comes under the case already con- 
 sidered, of species of a wide range, on page 14. If it had been shown that these 
 vines had been kept during the long Arctic winter in a warm, moist, equable at- 
 mosphere, as during the Carboniferous Period, and had continued to do well in the 
 Arctic summer, the case would have been analogous to that of the early flora, 
 but as there are no such conditions now in polar regions, the cases are entirely 
 different. 
 
14 DAY USE 
 
 RETURN TO DESK FROM WHICH BORROWED 
 
 This book is due on the last date stamped below, or 
 on the date to which renewed. 
 Renewed books are subject to immediate recall. 
 
 "* 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 LD21-35m-8,'72 
 (Q4189S10)476 A-32 
 
 General Library 
 
 University of California 
 
 Berkeley 
 
Pamphlet 
 
 Binder 
 Gaylord Bros. 
 
 Makers 
 
 Syracuse, N. Y. 
 PM.JAI 21,1308