 CHAPTER XIII THE SOLAR Eclipse of 1871 The First Telegrams This time we may fairly expect some approach to a solution of the riddle of the corona as the one essential which neither scientific skill nor government liberality could secure to the eclipse observers has been afforded, that is, fine weather. The telegraph has already informed us of this, and also that good use has been made of the good weather. From one station we are told, thin mist, spectroscopes satisfactory, reversion of lines entirely confirmed, six good photographs. From another, weather fine, telescopic and camera photographs successful, ditto polarization, good sketches, many bright lines in spectrum. This is very different from the gloomy accounts of the expedition of last year when we consider that the different observers are far apart, and that if all or some of them are similarly favored we shall have in the photographs a series of successive pictures, taken at intervals of time sufficiently distant to reveal any progressive changes that may have occurred in the corona while the moon's shadow was passing from one station to the other. I anticipate some curious revelations from these progressive photographs that may possibly reconcile the wide differences in the descriptions that competent observers have given of the corona of former eclipses which they had seen at stations distant from each other. Barely two years have elapsed since I suggested, in The Fuel of the Sun, that the great solar prominences and the corona are due to violent explosions of the dissociated elements of water, that the prominences are the gaseous flashes and the corona, the ejected scoria, or solidified metallic matter, belched forth by the furious cannonade continually in progress over the greater portion of the solar surface. This explanation at first appeared extravagant, especially as it was carried so far as to suggest that not merely the corona, but the zodiacal light, the zone of meteors which occasionally drop showers of solid matter upon the earth, and even the pocket planets or asteroids so irregularly scattered between the orbits of Mars and Jupiter, consist of solid matter thus ejected by the great solar eruptions. Even up to the spring of the present year, when Mr. Lockhear and other leaders of last year's expeditions reported their imperfect results and compared them with various theories, this one was not thought worthy of their attention. Since that time, during the past six or eight months, a change has taken place which strikingly illustrates the rapid progress of solar discovery. Observations and calculations of the force and velocity of particular solar eruptions have been made, and the results have proved that they are amply sufficient to eject solid missiles even further than I supposed them to be carried. Mr. Proctor, basing his calculations upon the observations of Respighi, Zölna and Professor Yang, has concluded that it is even possible that meteoric matter may be ejected far beyond the limits of our solar system into the domain of the gravitation of other stars, and that other stars may in like manner bombard the sun. This appears rather startling, but as I have already said, the imagination of the poet and the novelist is beggared by the facts revealed by the microscope, so I may now repeat the assertion and state it still more strongly in reference to the revelations of the telescope and the spectroscope. As a sample of these, I take the observations of Professor Yang, made on September 7th last and described fully in Nature on October 19th. He first observed a number of the usual flame prominences having the typical form which has been compared to a banyan grove. One of these banyans was greater than the rest. This monarch of the solar flame forest measured 54,000 miles in height, and its outspreading measured in one direction about 100,000 miles. It was a large eruption flame, but others much larger have been observed, and Professor Yang would probably have merely noted it among the rest, had not something further occurred. He was called away for twenty-five minutes, and when he returned, the whole thing had been literally blown to shreds by some inconceivable uprush from beneath. The space around was filled with flying debris, a mass of detached vertical fusiform filaments each from ten seconds to thirty seconds long by two seconds or three seconds wide, brighter and closer together where the pillars had formally stood and rapidly ascending. Professor Yang goes on to say that, when I first looked some of them had already reached a height of 100,000 miles, and while I watched they rose, with a motion almost perceptible to the eye, until in ten minutes the uppermost were 200,000 miles above the solar surface. This was ascertained by careful measurement. Here then, we have an observed velocity of 10,000 miles per minute, and this is the gaseous matter, merely the flash of the gun by which the particles of solidified solar matter are supposed to be projected. The reader must pause and reflect in order to form an adequate conception of the magnitudes he had treated, 100,000 miles long and 54,000 miles high. What does this mean? Twelve and a half of our worlds placed side by side to measure the length, and six and three quarters piled upon each other to measure the height. A few hundred worlds as large as ours would be required to fill up the whole cubic contents of this flame cloud. The spectroscope has shown that these prominences are incandescent hydrogen. Most of my readers have probably seen a soap bubble or a bladder filled with the separated elements of water, and then exploded, and have felt the ringing in their ears that has followed the violent detonation. Let them struggle with the conception of such a bubble or bladder magnified to the dimensions of only one such world as ours, and then exploded. Let them strain their power of imagination even to the splitting point, and still they must fail most pitifully to picture the magnitude of this solar explosion observed on September 7th last, which flashed out to a magnitude of more than 500 worlds, and then expanded to the size of more than 5,000 worlds, even while Professor Young was watching it. Professor Young concludes his description by stating that, it seems far from impossible that the mysterious coronal streamers, if they turn out to be truly solar, as now seems likely, may find their origin and explanation in such events. This and a number of similar admissions, suggestions and conclusions from the leading astronomers indicate that the eruption theory of the corona will not be passed over in silence by the observers of this eclipse, and it is to this that I have referred in the above remarks, respecting the interest attaching to a series of photographs showing successive states of this outspreading enigma. While Assetchi's spectroscopic observations on the uneclipsed sun led him to assert the existence of a stratum of glowing metallic vapours immediately below the envelope connected with the hydrogen of the eruptions. This is just what is required by my eruption theory to supply the solid materials of the ejections forming the corona. Professor Young's announcement of the reversal of the spectroscopic lines at the moment when the stratum was seen independently of the general solar glare startled Mr. Lockyer and others, who had disputed the accuracy of the observations of the great Italian observer as it confirmed them so completely. Skepticism still prevailed and Young's observation was questioned, but now even our slender telegraphic communication from Colonel Tennant to Dr. Huggins indicates that the question must be no longer contested. Reversion of lines entirely confirmed is a message so important that if the expeditions had done no more than this, all their cost in money and scientific labour would be amply repaired in the estimation of those who understand the value of pure truth. A few more fragments of intelligence respecting the eclipse expedition have reached us, the last Indian male having started just after the eclipse occurred. They fully confirm the first telegraphic announcement, rather strengthening than otherwise the expectations of important results, especially in reference to the photographs of the corona. I have read in the Salon newspapers some full descriptions by amateur observers in which the general magnificence of the phenomena is described. From these it is evident that the corona must have been displayed in its full grandeur, but as the writers do not attempt to describe those features, which have at the present moment a special scientific interest, I shall not dwell upon them, but await the publication of the official report of the chief and of the more important collateral observing expeditions. The unsophisticated reader may say, Hanot one man's eyes as good as another's, and why should the observations of the learned men of the expeditions be so much better than those of any other clear-sighted persons? This is a perfectly fair question and admits of a ready answer. All that can be known by mere unprepared naked eye observation is tolerably well known already. The questions which await solution can only be answered by putting the sun to torture by means of instruments specially devised for that purpose, and by a skillful organization and division of labor among the observers. There is so much to be seen during the few seconds of total obscuration that no one human being, however well trained in the art of observing, could possibly see all. Therefore it is necessary to pre-arrange each observer's part to have careful rehearsals of what is to be done by each during the precious seconds, and each man must exercise a vast amount of self-control in order to confine his attention to his own particular bit of observation while he is surrounded with such marvellous phenomena as a total eclipse presents. The grandeur of the gloomy landscape, the sudden starting out of the greater stars, the seeming falling of the vault of heaven, the silence of the animal world, the closing of the flowers, and all that the ordinary observer would regard with so much awe and wondering delight must be sacrificed by the philosopher whose business is to confine his gaze to a narrow slit between two strips of metal, and to watch nothing else but the exact position and appearance of a few bright or dark lines across what appears but a strip of colored ribbon. He must resist the temptation to look aside and around with the stubbornness of self-denial of another Saint Antonio. Besides this he must thoroughly understand exactly what to look for and how to find it. By combining the results of his observations with those of the others who in like manner have undertaken to work with another instrument or upon another part of the phenomena, we get a scientific result comparable to that which in a manufacturing we obtain by the division of labor of many skilled workmen, each doing only that which by his training he has learned to do the best and the most expeditiously. Further details by post. Although the formal official reports of the eclipse expedition are not yet published and may not be for some weeks or months, we are able from the letters of Lockyer, Jansen, Respiegi, McLeer, etc., to form some idea of the general results. We may already regard two or three important questions as fairly answered. The reversal of the dark solar lines of the spectrum, which was first announced by the great Roman observer Fadasetchi and seen by him without an eclipse, may now be considered as established. It is true that all the observers of 1871 did not witness this. Some were doubtful, but others observed it positively and distinctly. In such a case negative results do not refute the positive observations of qualified men, especially when several of such observations have been made independently. The phenomenon is but instantaneous, a mere flash of bright stripes in place of dark lines across the colour driven of the spectroscope, which happens just at the moment before and after totality and is presented only when the instrument is accurately directed to the delicate curved, vanishing thread of light, which is the last visible fragment of the solar outline and that which makes the first flash of his reappearance. A little explanation is necessary to render the significance of this reversal intelligible to those who have not specially studied the subject. First, when the spectroscope is directed to a luminous solid, a simple rainbow band or a continuous spectrum is seen. When, on the other hand, the object is a luminous gas or vapor of moderate density, the spectrum is not a continuous band with its colours actually blending. It consists only of certain luminous stripes with blank spaces between them. Each particular gas or vapor showing its own particular set of stripes of certain colours and always appearing at exactly the same place, so invariably and certainly that, by means of such luminous stripes, the composition of the gas or vapor may be determined. If, however, the gas be much compressed, the stripes widen as the condensation proceeds, they may even spread out sufficiently to meet and form a continuous spectrum like that from a solid. Liquids also produce continuous spectra. Second, when a luminous solid or liquid or very dense gas capable of producing a continuous spectrum is viewed through an intervening body of other gas or vapor of moderate or small density, fine dark lines cross the spectrum in precisely the same places as the bright stripes would appear if this intervening gas or vapor were luminous and seen by itself. When the spectroscope is directed to the face of the sun under ordinary circumstances, it presents a brilliant continuous spectrum, striped with a multitude of the dark lines. From this it has been inferred that the luminous face of the sun is that of an incandescent solid or liquid and that it is surrounded by the gases and vapors whose bright stripes, when artificially produced, occupy precisely the same places as the dark lines of the solar spectrum. This was the theory of Kirchhoff and others in the early days of spectrum analysis when it was only known that solids and liquids were capable of producing a continuous spectrum. The important discovery that gases and vapors, if sufficiently condensed, will also produce a continuous spectrum opened another speculation, far more consistent with the other known facts concerning the constitution of the sun, that is, that the sun may be a great gaseous orb blazing at its surface and gradually increasing in density from the surface towards the center. According to this, the metals sodium, calcium, barium, magnesium, iron, chromium, nickel, copper, zinc, strontium, cobalt, manganese, aluminium and titanium, whose vapors, with those of some few other substances, give the dark lines that cross the solar spectrum should exist neither as solids nor liquids on the solar surface, but as blazing gases. But such blazing gases, according to what I have stated above, should give us bright stripes instead of dark lines. Why, then, are not such bright stripes seen under ordinary circumstances? This is easily answered. These blazing gases must, as we proceed from the surface of the sun downwards, become so condensed by the pressure of their own super-incumbent strata as to produce a continuous spectrum of great brilliancy. With such a background, the bright stripes would be confounded and lost to sight. Besides this, the outer film of cooler vapor through which our vision must necessarily penetrate before reaching the luminous solar surface will produce the dark lines exactly where the bright stripes should be, and thus effectually obliterate them. Or, in other words, the intervening non-luminous vapors are opaque to the particular rays of light which the bright vapors of the same substance emits. Therefore, according to this theory, if we could sweep away these outside darkening vapors and screen off the inner layers of denser blazing matter which produces the continuous background, we should have a spectrum displaying a multitude of bright stripes exactly where the black lines of the ordinary solar spectrum appear. Setchi announced that these bright lines were to be seen under favorable circumstances, when, by skillful management, the rays from the edge of the sun were so caught by the slit of the spectroscope as to exhibit only the spectrum of the superficial layer of the sun's bright surface. This was disputed at the time by Mr. Lockyer, who, I suspect, omitted to consider the atmospheric difficulties under which English astronomers work, and the fact that the atmosphere of Italy is exceptionally favourable for delicate astronomical observation. If he had fairly considered this, I think he would agree with me in concluding that an observation of this kind, avowedly made with great difficulty and questionable distinctness by so skillful a spectroscopic observer as Father Setchi, could not possibly be seen by any human eyes through a London atmosphere. Subsequently, Professor Young startled the astronomical world by the announcement that, at the moment when the thinnest perceptible thread of the sun's edge was alone displayed during the eclipse which he observed, the whole of the dark lines of the solar spectrum flashed out as bright stripes in a most unmistakable manner. This observation is now fully confirmed. The first telegrams from Mr. Pogson, the government astronomer of Madras, and from Colonel Tennant, both announced this most positively, Colonel Tennant's words being, the reversion of the lines fully confirmed. A similar result was obtained by some, but not by all, of the salient observers. To understand this clearly, we must consider the fact that what appears to us as the outline of a flat disk is really that part of the sun which we see by looking horizontally a thwart his rotundity, just as we look at the ocean surface of our own earth when we stand upon the shore and see its horizon outline. When the moon obscures all but the last film of this solar edge, we see only the surface of the supposed gaseous orb, just that portion of the blazing gases which are not greatly compressed by those above them, and which accordingly should, if they consist of the vapours or the gases above named, display a bright striped spectrum, provided the intervening non-luminous vapours of the same metals are not sufficiently abundant to obscure them. At this particular moment, when only the absolute horizon line is seen, and the body of the moon cuts off all the intervening solar surface, and the lower or denser portion of the intervening super-solar vapours, though of course these are not so entirely cut off as the continuous background. The reversion of the dark lines therefore reveals to us the stupendous fact that the surface of the mighty sun, which is as big as a million and a quarter of our worlds, consists of a flaming ocean of hydrogen, and of the metals above named in a gaseous condition, similar to that of the hydrogen itself. This fact, coupled with the other revelations of the spectroscope, which, without the help of an eclipse, reveals the surface outline of the sun, the Sierra and the prominences tell us that this flaming ocean is in a state of perpetual tempest, heaving up its billows and flame alps hundreds and thousands of miles in height, and belching forth above all these still taller pillars of fire that even reach an elevation of more than a hundred thousand miles, and then burst out into mighty clouds of flame and vapour, bigger than five hundred worlds. What does the last eclipse teach us in reference to the corona? Firstly and clearly, that Lockyer's explanation, which attributed it to an illumination of the upper regions of the Earth's atmosphere, must be now forever abandoned. This theory has died hard, but in spite of Mr Lockyer's proclamation of victory all along the line, it is now past galvanizing. There can be no further hesitation in pronouncing that the corona actually belongs to the sun itself, that it is a marvellous solar appendage extending from the sun in all directions, but by no means regularly. The immensity of this appendage will be best understood by the fact that the space included within the outer limits of the visible corona is at least 20 times as great as the bulk of the sun itself, that above 25 millions of our worlds would be required to fill it. Jansen says, I believe the question whether the corona is due to the terrestrial atmosphere is settled, and we have before us the prospect of the study of the extra solar regions, which will be very interesting and fertile. The spectroscope, the polariscope and ordinary vision all concur in supporting the explanation that the corona is composed of solid particles and gaseous matter intermingled. It fulfills exactly all the requirements of the hypothesis, which attributes it to the same materials as those which in a gaseous state cause the reversion of the dark lines above described, but which have been ejected with the great eruptions forming the solar prominences and have become condensed into glowing metallic hailstones as their distance from the central heat has increased. These must necessarily be accompanied by the vapours of the more volatile materials and should give out some of the lighter gases, such as hydrogen, which, under greater pressure, would be occluded within them, just as the hydrogen gas occluded within the substance of the Leonardo meteor, a mass of iron which fell from the sky upon the earth, was extracted by the late master of the mint by means of his mercurial air pump. The rifts or gaps between the radial streamers, which have been so often described and figured, but were regarded by some as optical illusions, are now established as unquestionable facts. Mr. Lockyer, the last to be convinced, is now compelled to admit this, which overthrows the supposition that this solar appendage is a luminous solar atmosphere of any kind. If it were a gaseous or a true vapor, it must obey the law of gaseous diffusion, and could not present the phenomena of bright radial streamers, with dark spaces between them, unless it were in the course of very rapid radial motion, either to or from the sun. The photographs have not yet been published. When they have all arrived and can be compared, we shall learn something that I anticipate will be extremely interesting respecting the changes of the corona, as they have been taken at the different stations at different times. I alluded to this subject before, when it was only a matter of possibility that such a succession of pictures might have been taken. We now have the assurance that such pictures have been obtained. There can be no question about optical illusion in these. They are original affidavits made by the corona itself, signed, sealed, and delivered as its own act and deed. Matthew Williams Chapter 14 Meteoric Astronomy The number of the quarterly journal of science for May 1872 contains some articles of considerable interest. The first is by the indefatigable Mr. Proctor on meteoric astronomy, in which he embodies a clear and popular summary of the researches which have earned for Signor Schiaparelli this year's gold medal of the astronomical society. Like all who venture upon a broad, bold effort of scientific thought, extending at all into the regions of philosophical theory, Schiaparelli has had to wait for recognition. A simple and merely mechanical observation of a bare fact, barely and mechanically recorded, without the exercise of any other of the intellectual faculties than the external senses and observing powers, is at once received and duly honored by the scientific world. But any higher effort is received at first indifferently, or skeptically, and is only accepted after a period of probation, directly proportionate to its philosophical magnitude and importance, and inversely proportionate to the scientific status of the daring theorist. At first sight this appears unjust. It looks like honoring the laborers who merely make the bricks and despising the architect who constructs the edifice of philosophy from the materials they provide. Many a disappointed dreamer finding that his theory of the universe has not been accepted, and that the expected honors have not been showered upon him, has violently attacked the whole scientific community as a contemptible gang of low-minded mechanical plotters void of imagination blind to all poetic aspirations and incapable of any grand and comprehensive flight of intellect. Had these impulsive gentlemen been previously subjected to the strict discipline of inductive scientific training, their position and opinions would have been very different. Their great theories would either have had no existence, or have been much smaller, and they would understand that philosophic caution is one of the characteristic results of scientific training. Simple facts which can be immediately proved by simple experiments and simple observations are at once accepted, and their discoverers duly honored without any hesitation or delay. But the grander efforts of generalization require careful thought and laborious scrutiny for their verification, and therefore the acknowledgement of their merits is necessarily delayed. But when it does arrive, full justice is usually done. Thus Grove's correlation of the physical forces, the greatest philosophical work on purely physical science of this generation, was commenced in 1842, when its author occupied but a humble position at the London institution. The book was but little noticed for many years, and had Mr. Grove, now Sir William Grove, not been duly educated by the discipline above referred to, he might have become a noisy cantankerous martyr, one of those ill-used men who have been made familiar to so many audiences by Mr. George Dawson. Instead of this, he patiently waited, and as we have lately seen, the well-deserved honors have now been liberally awarded. In a very few years hence, we shall be able to say the same of the once diabolical Darwin, and eight or nine other theorists who must all be content to take their trial and patiently await the verdict, the time of waiting being of necessity proportionate to the magnitude of the issue. The theories of Schiapparelli, which as Mr. Proctor says, after the usual term of doubt have so recently received the sanction of the highest astronomical tribunal of Great Britain, are not of so purely speculative a character as to demand a very long term of doubt. They are directly based on observations and mathematical calculations, which bring them under the domain of the recognized logic of mathematical probability. Those who are especially interested in the modern progress of astronomy should read this article in the Quarterly Journal of Science, which is illustrated with the diagrams necessary for the comprehension of the researches and reasoning of Schiapparelli and others who have worked on the same ground. I can only state the general results, which are that the meteors which we see every year, more or less abundantly, on the nights of the 10th and 11th of August, and which always appear to come from the same point in the heavens, are then and thus visible because they form part of an eccentric elliptical zone of meteoric bodies which girdle the domain of the sun, and that our earth in the course of its annual journey around the sun crosses and plunges more or less deeply into this ellipse of small attendant bodies which are supposed to be moving in regular orbits around the sun. Schiapparelli has compared the position, the direction, and the velocity of motion of the August meteors with the orbit of the Great Comet of 1862, and infers that there is a close connection between them, so close that the meteors may be regarded as a sort of trail which the comet has left behind. He does not exactly say that they are detached vertebrae of the comet's tail, but suggests the possibility of their original connection with its head. Similar observations have been made upon the November meteoric showers, which by similar reasoning are associated with another comet, and further yet it is assumed upon analogy that other recognized meteor systems, amounting to nearly 200 in number, are in like manner associated with other comets. If these theories are sound, our diagrams and mental pictures of the solar system must be materially modified. Besides the central sun, the eight planets and the asteroids moving in their nearly circular orbits, and some eccentric comets traveling in long ellipses, we must add a countless multitude of small bodies clustered in elliptical rings all traveling together in the path marked by their containing girdle, and following the lead of a streaming, vaporous monster, their parent comet. We must count such comets and such rings filled with attendant fragments, not merely by tens or hundreds, but by thousands and tens of thousands, even by millions. The path of the earth being but a thread in space, and yet a hundred or two are strong upon it. In this article, Mr. Proctor seems strongly disposed to return to the theory, which attributes solar heat and light to a bombardment of meteors from without, and the solar corona and zodiacal light as visible presentments of these meteors. Still, however, he clings to the more recent explanation which regards the corona, the zodiacal light, and the meteors as matter ejected from the sun by the same forces as those producing the solar prominences. For my own part, I shall not be at all surprised if we find that, ere long, these two apparently conflicting hypotheses are fully reconciled. The progress of solar discovery has been so great since January 1870 when my ejection theory was published that I may now carry it out much further than I then dared, or was justified in daring to venture. Actual measurement of the projectile forces displayed in some of the larger prominences renders it not merely possible, but even very probable, that some of the exceptionally great eruptive efforts of the sun may be sufficiently powerful to eject solar material beyond the reclaiming reach of its own gravitating power. In such a case, the banished matter must go on wandering through the boundless profundity of space until it reaches the domain of some other sun, which will clutch the fragment with its gravitating energies, and turn its straight and ever-onward course into the curved orbit. Thus the truant marsil from our sun will become the subject of another sun, a portion of another solar system. What one sun may do, another and every other may do likewise, and if so there must be a mutual bombardment, a ceaseless interchange of matter between the countless suns of the universe. This is a startling view of our cosmical relations, but we are driving rapidly towards a general recognition of it. The November star showers have perpetrated some irregularities this year. They have been very unpunctual and have not come from their right place. We have heard something from Italy, but not the tidings of the Leonides that were expected. Instead of the great display of the month occurring on the 13th and 14th, it was seen on the 27th. We have accounts from different parts of England, Ireland, Scotland, and Wells also from Italy, Greece, Egypt, etc. Mr. Slento, in a letter to the Times, estimates the number seen at Suez as reaching at least 30,000, while in Italy and Athens, about 200 per minute were observed. They were not, however, the Leonides. That is, they did not radiate from a point in the constellation Leo, but from the region of Andromeda. Therefore, they were distinct from that system of small wanderers usually designated the November meteors, were not connected with the temple's comet, but belong to quite another set. The question now discussed by astronomers is whether they are connected with any other comet, and if so, with which comet. In the monthly notices of the Royal Astronomical Society, published October 24th, last, is a very interesting paper by Professor Herschel on observations of meteor showers. Supposed to be connected with Bealus Comet, in which he recommends that a watch should be kept during the last week in November and the first week in December, in order to verify the ingenious suggestions of Dr. Weiss, which popularly stated amount to this, is that a meteoric cloud is revolving in the same orbit as Bealus Comet, and that in 1772, the Earth dashed through this meteoric orbit on December 10th. In 1826, it did the same on December 4th. In 1852, the Earth passed through the node on November 28th, and there are reasons for expecting a repetition at about the same date in 1872. The magnificent display of the 27th has afforded an important verification of these anticipations, which become especially interesting in connection with the curious history of Bealus Comet, which receives its name from M. Beala of Josephstadt, who observed it in 1826, calculated its orbit, and considered it identical with the comets of 1772, 1805, etc. It travels in a long eccentric ellipse and completes its orbit in 2,410 days, about six and three-quarter years. It appeared again, as predicted, in 1832 and 1846. Its orbit very nearly intersects that of the Earth, and thus affords a remote possibility of that sort of collision which has excited so much terror in the minds of many people, but which an enthusiastic astronomer of the present generation would anticipate with something like the sensational interest, which steers the soul of a London street boy when he is madly struggling to keep pace with a fire engine. The calculations for 1832 showed that this comet should cross the Earth's orbit a little before the time of the Earth's arrival at the same place. But as such a comet traveling in such an orbit is liable to possible retardations, the calculations could only be approximately accurate, and thus the sensational astronomer was not altogether without hope. This time, however, he was disappointed. The comet was punctual and crossed the critical node about a month before the Earth reached it. As though to compensate for this disappointment, the comet at its next appearance exhibited some entirely new phenomena. It split itself into two comets in such a manner that the performance was visible to the telescopic observer. Both of these comets had nuclei and short tails, and they alternately varied in brightness, sometimes one, then the other having the advantage. They traveled on at a distance of about 156,000 miles from each other, with parallel tells and with a sort of friendly communication in the form of a faint arc of light, which extended as a kind of bridge from one to the other. Besides this, the one which was first the brighter than the fainter, and finally the brighter again, threw out two additional tails, one of which extended lovingly towards its companion. The time of return in 1852 was, of course, anxiously expected by astronomers, and careful watch was kept for the wanderers. They came again at the calculated time still separated as before. They were again due in 1859 in 1866 and finally at about the end of last November, or the beginning of the present month. Though eagerly looked for by astronomers in all parts of the civilized world, they have been seen no more since 1852. What then has become of them? Have they further subdivided? Have they crumbled into meteoric dust? Have they blazed or boiled into thin air? Or have they been dragged by some interfering gravitation into another orbit? The last supposition is the most improbable, as none of the visible inhabitants of space have come near enough to disturb them. The possibility of a dissolution into smaller fragments is suggested by the fact that, instead of the original single comet, or the two fragments, meteoric showers have fallen towards the earth at the time when it has crossed the orbit of the original comet, and these showers have radiated from that part of the heavens in which the comet should have peered. Such was the case with the magnificent display of November 27th, and astronomers are inclining more and more to the idea that comets and meteors have a common origin. The meteors are little comets, or comets are big meteors. In the latest of the monthly notices of the Royal Astronomical Society published last week is a paper by Mr. Proctor in which he expands the theory expounded three years ago, by an author whom your correspondence modesty prevents him from naming. That the larger planets, Jupiter, Saturn, Uranus, and Neptune, are minor suns, ejecting meteoric matter from them by the operation of forces similar to those producing the solar prominences. Mr. Proctor subjects this bold hypothesis to mathematical examination, and finds that the orbit of the temple's comet and its companion meteors correspond to that which would result from such an eruption occurring on the planet Uranus. An eruptive force affecting a velocity of about 13 miles per second, which is vastly smaller than the actually measured velocity of the matter of the solar eruptions, would be sufficient to thrust such meteoric or cometary matter beyond the reclaiming reach of the gravitation of Uranus, and hand it over to the sun to make just such an orbit as that of temple's comet and the Leonides meteors. He shows that other comets and meteoric zones are similarly allied to other planets, and thus it may be that the falling stars and comets are fragments of Jupiter, Saturn, Uranus, or Neptune. Verily, if an astronomer of the last generation were to start up among us now, he would be astounded at modern presumption. The star shower of November 27th, and its connection with Biela's broken and lost comet, referred to in my last letter, are still subjects of research and speculation. On November 30th, Professor Clinkerfus sent to Mr. Pogson of the Madras Observatory the following startling telegram, Biela Touched Earth on 27th. Search near Theta Centauri. Mr. Pogson searched accordingly from Comet Rise to Sunrise on the two following mornings, but in vain. For even in India they have had cloudy weather of late. On the third day, however, he had better luck, saw something like a comet through an opening between clouds, and on the following days was enabled to deliberately verify this observation and determine the position and some elements of the motion of the comet, which displayed a bright nucleus and faint but distinct tail. This discovery is rather remarkable in connection with the theoretical anticipation of Professor Clinkerfus, but the conclusion directly suggested is by no means admitted by astronomers. Some have supposed that it is not the primary Biela but the secondary comet or offshoot, which grazed the earth and was seen by Mr. Pogson. Others that it was neither the body, the envelope nor the tail of either of the comets which formed the star shower, but that the meteors of November 27th were merely a trail which the comet left behind. A multitude of letters were read at the last and previous meeting of the astronomical society in which the writers described the details of their own observations. As these letters came from nearly all parts of the world, the data have an unusual degree of completeness and show very strikingly the value of the work of amateur astronomical observers. By the correlation and comparison of these, important inductions are obtainable. Thus, Professor A. S. Herschel concludes that the earth passed through seven strata of meteoric bodies having each a thickness of about 50,000 miles, in all about 350,000 miles. As the diameter of the visible nebulosity of Biela's comet was but 40,000 miles when nearest the earth in 1832, the great thickness of these strata indicates something beyond the comet itself. Besides this, Mr. Hine's calculation for the return of the primary comet shows that on November 27th it was 250 millions of miles from the earth. Those however who are determined to enjoy the sensation of supposing that they really have been brushed by the tail of a comet still have the secondary comet to fall back upon. This as already described was broken off the original from which it was seen gradually to diverge, but was still linked to it by an arch of nebulous matter. If this divergence has continued it must now be far distant, sufficiently far to afford me an opportunity of safely adding another to the numerous speculations that we may on November 27th have plunged obliquely through this connecting arm of nebulous matter which was seen stretching between the parent comet and its offshoot. The actual position of the meteoric strata above referred to is quite consistent with the hypothesis. The Great Ice Age and the Origin of the Till. The growth of science is becoming so overwhelming that the old subdivisions of human knowledge are no longer sufficient for the purpose of dividing the labor of experts. It is scarcely possible now for any man to become a naturalist a chemist or a physicist in the full sense of either term. He must, if he aims at thoroughness, be satisfied with the general knowledge of the great body of science and a special and a full acquaintance with only one or two of its minor subdivisions. Thus geology, though but a branch of natural history and the youngest of its branches has now become so extensive that its ableist votaries are compelled to devote their best efforts to the study of sections which, but a few years ago, were scarcely definable. Glaciation is one of these, which now demands its own elementary textbooks over and above the monographs of original investigators. This demand has been well supplied by Mr. James Geeky in The Great Ice Age, of which a second edition has just been issued. Every student of glacial phenomena owes to Mr. Geeky a heavy debt of gratitude for the invaluable collection of facts and philosophy which this work presents. It may now be fairly described as a standard treatise on the subject which it treats. One leading feature of the work offers a very aggressive invitation to criticism. Scotchmen are commonly accused of looking upon the whole universe through Scotch spectacles, and here we have a Scotchman treating a subject which affects nearly the whole of the globe and devoting about half of his book to the details of Scottish glacial deposits. While England has one third of the space allowed to Scotland, Ireland but a thirtieth, Scandinavia less than a tenth, North America a sixth, and so on with the rest of the world. Disproportionate as this may appear at first glance, further acquaintance with the work justifies the preeminence which Mr. Geeky gives to the Scotch glacial deposits. Accepting Norway, there is no country in Europe which affords so fine a field for the study of the vestiges of extinct glaciers as Scotland, and Scotland has an advantage even over Norway in being much better known in geological detail. Besides this, we always must permit the expounder of any subject to select his own typical illustrations and welcome his ability to find them in a region which he himself has directly explored. Mr. Geeky's connection with the geological survey of Scotland has afforded him special facilities for making good use of Scottish typical material, and he has turned these opportunities to such excellent account that no student after reading The Great Ice Age will find fault with its decided nationality. The leading feature, the basis in fact of this work, deserves a special notice as it gives it a peculiar and timely value of its own. This feature is that the subject as compared with its usual treatment by other leading writers is turned round and presented, so to speak, bottom upwards. Des saucieux, charpentiers, aghaziz, humboldt, forbes, hopkins, wewo, stark, tindle, etc. have studied the living glaciers, and upon the data thus obtained have identified the work of extinct glaciers. Chronologically speaking, they have proceeded backwards, a method absolutely necessary in the early stages of the inquiry, and which has yielded admirable results. Geeky, in the work before us, proceeds exactly in the opposite order, availing himself of the means of identifying glacial deposits which the retrogressive method affords. He plunges at once to the lowest and oldest of these deposits, which he presents the most prominently, and then works upwards and onwards to recent glaciation. The best illustration I can offer of the timely advantage of this reverse treatment is, with due apology for necessary egotism, to state my own case. In 1841, when the glacial hypothesis, as it was then called, was in its infancy, Professor Jameson, although very old and nearly at the end of his career, took up the subject with great enthusiasm, and devoted it to a rather disproportionate number of lectures during his course on natural history. Like many of his pupils, I became infected by his enthusiasm, and went from Edinburgh to Switzerland, where I had the good fortune to find Agassiz and his merry men at the Hotel des Nuches de Lois. Two tents raised upon a magnificent boulder, floating on the upper part of the R Glacier. After a short but very active sojourn there, I did, not without physical danger, many other glaciers in Switzerland and the Tirol, and afterwards practically studied the subject in Norway, North Wales, and wherever else an opportunity offered, reading in the meantime much of its special literature. But, like many others, confining my reading chiefly to authors who start with living glaciers and describe their doings most prominently, when, however, I read the first edition of Mr. Geeky's Great Ice Age, immediately after its publication, his mode of presenting the phenomena bottom upwards suggested a number of reflections that had never occurred before, leading to other than the usual explanations of many glacial phenomena, and correcting some errors into which I had fallen in searching for the vestiges of ancient glaciers. As these suggestions and corrections may be interesting to others, as they have been to myself, I will here state them in outline. The most prominent and puzzling reflection or conclusion suggested by reading Mr. Geeky's description of the glacial deposits of Scotland was that the great bulk of them are quite different from the deposits of existing glaciers. This reminded me of a previous puzzle and disappointment that I had met in Norway, where I had observed such abundance of striation, such universality of polished rocks and rounded mountains, and so many striking examples of perched blocks, with scarcely any decent vestiges of moraines. This was especially the case in Arctic Norway, coasting from Trondheim to Hammerfest, winding round glaciated islands in and out of fjords banked with glaciated rock slopes, along more than a thousand miles of shoreline, displaying the outlets of a thousand ancient glacier valleys, scanning eagerly throughout from sea to summit, landing at several stations, and climbing the most commanding hills. I saw only one ancient moraine that the Oxford Station described in Through Norway with Ladies, but this negative anomaly is not all. The ancient glacial deposits are not only remarkable on account of the absence of the most characteristic of modern glacial deposits, but in consisting mainly of something which is quite different from any of the deposits actually formed by any of the modern glaciers of Switzerland or any other country within the temperate zones. I have seen nothing either at the foot or the sides of any living alpine or Scandinavian glacier that even approximately represents the till or boulder clay, nor any description of such a formation by any other observer, and have met with no note of this very suggestive anomaly by any writer on glaciers. Yet the till and boulder clay form vast deposits, covering thousands of square miles, even of the limited area of the British Isles, and constitute the main evidence upon which we base all our theories, respecting the existence and the vast extent and influence of the Great Ice Age. Although so different from anything at present produced by the alpine or Scandinavian glaciers, this great deposit is unquestionably of glacial origin. The evidences upon which this general conclusion rests are fully stated by Mr. Geeky, and may safely be accepted as incontrovertible. Once then, the great difference, one of the suggestions to which I have already alluded, as afforded by reading Mr. Geeky's book, was a hypothetical solution of this difficulty, but the verification of the hypothesis demanded a revisit to Norway. An opportunity for this was afforded in the summer of 1874, during which I traveled around the coast of Stavanger to the Arctic frontier of Russia, and through an interesting inland district. The observations there, made and strengthened by subsequent reflections, have so far confirmed my original speculative hypothesis that I now venture to state it briefly as follows, that the period appropriately designated by Mr. Geeky as the Great Ice Age includes at least two distinct periods, or epochs. The first of very great intensity or magnitude during which the Arctic regions of our globe were as completely glaciated as the Antarctic now are, and the British islands and a large portion of Northern Europe were glaciated as completely and nearly in the same manner as Greenland is at the present time. That long after this, and immediately preceding the present geological epoch, there was a minor glacial period when only the now existing valleys favorably shaped and situated for glacial accumulations were partially or wholly filled with ice. There may have been many intermediate fluctuations of climate and glaciation, and probably worth such, but as these do not affect my present argument they need not be here considered. So far I agree with the general conclusions of Mr. Geeky as I understand them, and with the generally received hypotheses, but in what follows I venture to diverge materially. It appears to me that the existing Antarctic glaciers and some of the glaciers of Greenland are essentially different in their conformation from the present glaciers of the Alps, and from those now occupying some of the fields and valleys of Norway, and that the glaciers of the earlier or greater glacial epoch were similar to those now forming the Antarctic barrier, while the glaciers of the later or minor glacial epoch resembled those now existing in temper climates, or were intermediate between these and the Antarctic glaciers. The nature of the difference which I suppose to exist between the two classes of glaciers is this. The glaciers, properly so called, of temper climates are the overflow of the Neve, the great reservoir of ice and snow above the snowline. They are composed of ice which is protruded below the snowline into the region where the summer thaw exceeds the winter snowfall. This ice is necessarily subject to continual thinning or wasting from its upper or exposed surface, and thus finally becomes liquefied and is terminated by direct solar action. Many of the characteristic phenomena of alpine glaciers depend upon this, among the more prominent of which are the superficial extrusion of boulders or rock fragments that have been buried in the Neve, or have fallen into the crevasses of the upper part of the true glacier, and the final deposit of these same boulders of fragments at the foot of the glaciers forming ordinary maranes. But this is not all. The thawing which extrudes and finally deposits the larger fragments of rock sifts from them the smaller particles, the aggregate bulk of which usually exceeds very largely that of the larger fragments. This fine silt, or sand, thus washed away, is carried by the turbid glacier torrent to considerable distances and deposit as an alluvium wherever the agitated waters find a resting place. Thus the debris of the ordinary modern glacier is effectively separated into two or more very distinct deposits, the moraine at the glacier foot consisting of rock fragments of considerable size with very little sand or clay or other fine deposit between them, and a distant deposit of totally different character, consisting of gravel, sand, clay or mud according to the length and conditions of its journey. The chips as they have been well called are thus separated from what I may designate the filings or sawdust of the glacier. The filings from the existing glaciers of the Bernese Alps are gradually filling up the lake basins of Geneva and Constance, repairing the breaches made by the erosive action of their gigantic predecessors. Those of the southern slope of the Alps are doing a large share in filling up the Adriatic, while the chips of all merely rest upon the glacier beds forming the comparatively insignificant terminal moraine deposits. The same in Scandinavia, the Stolf of the Jostadal is fed by the melting of the Krondal, Nygaard, Bjornsteg and Soldal glaciers. It is filled up a branch of the deep Sogniford, forming an extensive fertile plain at the mouth of its wild valley, and is depositing another sub-aqueous plain beyond. While the moraines of the glaciers are but inconsiderable and comparatively insignificant heaps of loose boulders, spread out on the present and former shores of the above named glaciers, which are overflows from one side of the Great Neve, the Jostadal Schneefand. All of these glaciers flow down small lateral valleys, spread out, and disappear in the main valley, which has now no glacier of its own, though it was formerly glaciated throughout. What must have been the condition of this and the other Great Scandinavian valleys when such was the case? To answer this question rationally, we must consider the meteorological conditions of that period. Either the climate must have been much colder, or the amount of precipitation vastly greater than at present. In order to produce the general glaciation that rounded the mountains up to a height of some thousands of feet above the present sea level, probably both factors cooperated to affect this vast glaciation. The climate colder and the snowfall also greater. The whole of Scandinavia, or as much as then stood above the sea, must have been a Neve or Schneefand on which the annual snowfall exceeded the annual thaw. This is the case at present on the largest Neve of Europe, the 500 square miles of the Great Plateau of the Jostadals and Nordfjords Schneefand. On all the overflowing Neve or snow fields of the Alps above the snowline, over the greater part of Greenland, and as the structure of the southern icebergs prove, everywhere within the Great Antarctic Ice Barrier. What then must happen when the snowline comes down, or nearly down, to the sea level? It is evident that the outthrust glaciers, the overflowed down the valleys, cannot come to an end like the present Swiss and Scandinavian glaciers by the direct melting action of the sun. They may be somewhat thin from below by the heat of the earth, and that generated by their own friction on the rocks, but these must be quite inadequate to overcome the perpetual accumulation due to the snowfall upon their own surface and the vast overflow from the great snow fields above. They must go on and on, ever increasing until they meet some new condition of climate, or some other powerful agent of dissipation, something that can effectively melt them. This agent is very near at hand in the case of the Scandinavian valleys and those of Scotland. It is the sea. I think I may safely say that the valley glaciers of these countries during the Great Ice Age must have reached the sea, and there have terminated their existence, just as the Antarctic glaciers terminate at the present Antarctic ice wall. What must happen when a glacier is thus thrust out to sea? This question is usually answered by assuming that it slides along the bottom until it reaches such a depth that flotation commences and then it breaks off, or calves, as icebergs. This view is strongly expressed by Mr. Geeky on page 47, when he says that the seaward portion of an Arctic glacier cannot by any possibility be floated up without sundering its connection with the frozen mass behind. So long as the bulk of the glacier much exceeds the depth of the sea, the ice will of course rest upon the bed of the fjord or bay without being subjected to any strain or tension. But when the glacier creeps outwards to greater depths, then the superior specific gravity of the sea water will tend to press the ice upward. That ice, however, is a hard continuous mass, with sufficient cohesion to oppose for a time this pressure, and hence the glacier crawls on to a depth far beyond the point at which, had it been free, it would have risen to the surface and floated. If at this great depth the whole mass of the glacier could be buoyed up without breaking off, it would certainly go to prove that the ice of Arctic regions, unlike ice anywhere else, had the property of yielding to mechanical strain without rupturing, but the great tension to which it is subjected takes effect in the usual way, and the ice yields not by bending and stretching, but by breaking. Mr. Geeky illustrates this by a diagram showing the calving of an iceberg. In spite of my respect for Mr. Geeky as a geological authority, I have no hesitation in contradicting some of the physical assumptions included in the above. Ice has no such rigidity, as here stated. It does possess, in a high degree, the property of yielding to mechanical strain without rupturing. We need not go far for evidence of this. Everybody who has skated or seen others skating on ice, that is, but just thick enough to bear, must have felt or seen it yield to the mechanical strain of the skater's weight. Under these conditions, it not only bends under him, but it afterwards yields to the reaction of the water below, rising and falling in visible undulations, demonstrating, most unequivocally, a considerable degree of flexibility. It may be said that in this case, the flexibility is due to the thinness of the ice, but this argument is unsound, in as much as the manifestation of such flexibility does not depend upon absolute thickness or thinness, but upon the relation of thickness to superficial extension. If a thin sheet of ice can be bent to a given arc, a thick sheet may be bent in the same degree, but the thicker ice demands a greater radius and proportionate extension of circumference. But we have direct evidence that ice of great thickness, actual glaciers, may bend to a considerable curvature before breaking. This is seen very strikingly when the uncravasse ice sheet of a slightly inclined neve suddenly reaches a precipice and is thrust over it. If Mr. Geeky were right, the projecting cornice thus formed should stand straight out, and then, when the transverse strain due to the weight of this rigid overhang exceeded the resistance of tenacity, it should break off short, exposing a face at right angles to the general surface of the supported body of ice. Had Mr. Geeky ever seen and carefully observed such an overhang or cornice of ice, I suspect that the abovecoated passage would not have been written. Some very fine examples of such ice cornices are well seen from the ridge separating the Hanspikjen Fjeld from the head of the Jostedal, where a view of the great neve or Schneefand is obtained. This side of the neve terminates in precipitous rock walls. At the foot of one of these is a dreary lake, the Steigevand. The overflow of the neve here forms great bending sheets that reach a short way down, and then break off and drop as small icebergs into the lake. The ordinary course of glaciers affords abundant illustrations of the plasticity of such masses of ice. They spread out where the valley widens, contract where the valley narrows, and follow all the convexities or concavities of the axial line of its bed. If the bending thus enforced exceeds a certain degree of abruptness, crevasses are formed, but a considerable bending occurs before the rupture is affected, and crevasses of considerable magnitude are commonly formed without severing one part of a glacier from another. They are usually v-shaped in vertical section, and in many the rupture does not reach the bottom of the glacier. Very rarely indeed does a crevasse cross the whole breadth of a glacier in such a manner as to completely separate, even temporarily, the lower from the upper part of the glacier. If a glacier can thus bend downwards without sundering its connections with the frozen mass behind, surely it may bend upwards in a corresponding degree, either with or without the formation of crevasses according to the thickness of the ice and the degree of curvature. A glacier reaching the sea by a very steep incline would probably break off, in accordance with Mr. Geeky's description, just as an alpine glacier is ruptured fairly across when it makes a cascade over a suddenly precipitous bend of its path. One entering the sea at an inclination, somewhat less precipitous than the minor limit of the effective rupture gradient, would be crevassed in a contrary manner to the crevassing of alpine glaciers. Its crevasses would gape downwards instead of upwards, have lambda-shaped instead of a V-shaped section. With a still, more moderate slope, the up-floating of the termination of the glacier, and a concurrent general uplifting or up-bending of the whole of its submerged portion, might occur without even a partial rupture or crevasse formation occurring. Let us now follow out some of the necessary results of these conditions of glacier existence and glacial prolongation. The first and most notable, by its contrast with ordinary glaciers, is the absence of lateral, medial, or terminal moraines. The larger masses of debris, the chippings that may have fallen from the exposed escarpments of the mountains upon the surface of the upper regions of the glacier, instead of remaining on the surface of the ice and standing above its general level by protecting the ice, on which they rest from the general snow thaw, would become buried by the upward accretion of the ice due to the unthought stratum of each year's snowfall. The thinning agency at work upon such glaciers during their journey over the terra firma, being the outflow of terrestrial heat, and that due to their friction upon their beds, this thinning must all take place from below, and thus as the glaciers proceed downwards, these rock fragments must be continually approaching the bottom instead of continually approaching the top, as in the case of modern alpine glaciers flowing below the snowline and thawing from surface downwards. It follows therefore that such glaciers could not deposit any moraines, such as are in course of deposition, by existing alpine and Scandinavian glaciers. What then must become of the chips and filings of these outfloating glaciers? They must be carried along with the ice so long as that ice rests upon the land. For this debris must consist partly of fragments embedded in the ice, and partly of ground and reground excessively subdivided particles that must either cake into what I may call ice mud, and become a part of the glacier, or flow as liquid mud or turbid water beneath it, as with ordinary glaciers. The quantity of water being relatively small under the supposed conditions, the greater part would be carried forward to the sea by the ice rather than by the water. An important consequence of this must be that the erosive power of these ancient glaciers was Cateris peribus, greater than that of modern alpine glaciers, especially if we accept those theories would describe an actual internal growth or regeneration of glaciers by the relegation below of some of the water resulting from the surface thaw. As the glacier with its lower accumulation advances into deeper and deeper water, its pressure upon its bed must progressively diminish until it reaches a line where it would just graze the bottom with a touch of feathery lightness. Somewhere before reaching this, it would begin to deposit its burden on the sea bottom, the commencement of this deposition being determined by the depth where at the tenacity of the deposit or its friction against the sea bottom or both combined becomes sufficient to overpower the now diminished pressure and forward thrusting or erosive power of the glacier. Further forward, in deeper water, where the ice becomes fairly floated above the original sea bottom, a rapid under thawing must occur by the action of the sea water, and if any communication exists between this ice covered sea and the waters of warmer latitudes, this thawing must be increased by the currents that would necessarily be formed by the interchange of water of varying specific gravities. Deposition would thus take place in this deeper water, continually shallowing it or bringing up the sea bottom nearer to the ice bottom. This raising of the sea bottom must occur not only here, but farther back, i.e. from the limit at which deposition commenced. This neutral ground, where at the depth is just sufficient to allow the ice to rest lightly on its own deposit and slide over it without either sweeping it forward or depositing any more upon it, becomes an interesting critical region, subject to continuous forward extension during the lifetime of the glacier, as the deposition beyond it must continually raise the sea bottom until it reaches the critical depth at which the deposition must cease. This would constitute what I may designate the normal depth of the glaciated sea, or the depth towards which it would be continually tending during a great glacial epoch by the formation of a submarine bank or plane of glacier deposit, over which the glacier would slide without either grinding it lower by erosion or raising it higher by deposition. But what must be the nature of this deposit? It is evident that it cannot be a mere moraine consisting only of the larger fragments of rock, such as are now deposited at the foot of glaciers that die before reaching the sea. Neither can it correspond to the glacial silt which is washed away and separated from these larger fragments by glacial streams and deposited at the outspreadings of glacier torrents and rivers. It will correspond to neither the assorted gravel, sand, nor mud of these alluvial deposits, but must be an agglomeration of all the infusible solid matter the glacier is capable of carrying. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. It must contain, in heterogeneous admixture, the great boulders, the lesser rock fragments, the gravel chips, the sand, and the slimy mud. These settling down quietly in the cold, gloomy waters, overshadowed by the great ice sheet, must form such an agglomeration, as we find in the boulder clay and tills, and lie just in those places where these deposits abound. Provided the relative level of land and sea during the glacial epoch were suitable. I should make one additional remark relative to the composition of this deposit. Viz, that under the conditions proposed, the original material detached from the rocks around the upper portions of the glaciers would suffer a far greater degree of attrition at the glacier bottom than it obtains in modern alpine glaciers. In as much as in these, it is removed by the glacier torrent which it has attained a certain degree of fineness. While in the greater glaciers of the glacial epoch, it would be carried much further in association with the solid ice, and be subjected to more grinding and regrinding against the bottom. Hence a larger portion of slimy mud would be formed, capable of finally enduring into stiff clay such as forms the matrix of the till and boulder clay. The long journey of the bottom debris stratum of the glacier, and its final deposition went in a state of neutral equilibrium between its own tendency to repose and the forward thrust of the glacier, would obviously tend to arrange the larger fragments of rock in the manner in which they are found embedded in the till, i.e. the oblong fragments lying with their longer axes and their best marked striae in the direction of the motion of the glacier. The striated pavements of the till are thus easily explained. They are the surface upon which the ice advanced when its deposits had reached the critical or neutral height. Such a pavement would continually extend outwards. The only sorting of the material likely to occur under these conditions would be that due to the earlier deposition and entanglement of the larger fragments. Thus producing a more stony deposit nearer inland just as Mr. Geeky describes the actual deposits of till where, generally speaking, the stones are most numerous in the till of hilly districts. While at the lower levels of the country, the clay character of the mass is upon the whole more pronounced, these hilly districts upon the supposition of greater submergence would be the near shore regions and the lower levels the deeper sea where the glacier floated freely. The following is Mr. Geeky's description of the distribution of the till, page 13. It is in the lower lying districts of the country where till appears in greatest force. Wide areas of the central counties are covered up with it continuously to a depth varying from two or three feet up to 100 feet and more, but as we follow it towards the mountain regions, it becomes thinner and more interrupted. The naked rock ever and anon peering through until at least we find only a few shreds and patches lying here and there in sheltered hollows of the hills. Throughout the Northern Highlands it occurs but rarely and only in little isolated patches. It is not until we get away from the steep rocky declivities and narrow glens and gorges and enter upon the broader valleys that open out from the base of the Highland Mountains to the low lying districts beyond that we meet with any considerable deposits of stony clay. The higher districts of the southern uplands are almost equally free from any covering of till. This description is precisely the same as I must have written had I so far continued my imaginary sketch of the results of ancient glaciation as to picture what must remain after the glaciers had all melted away and the sea had receded sufficiently to expose their submarine deposits. Throughout the above I have assumed a considerable submergence of the land as compared with the present sea level on the coast of Scotland, Scandinavia, etc. The universality of the terraces in all the Norwegian valleys opening westward proves a submergence of at least 600 or 700 feet. When I first visited Norway in 1856 I accepted the usual description of these as alluvial deposits, was looking for glacial vestiges in the form of moraines and thus quite failed to observe the true nature of these vast accumulations which was obvious enough when I re-examined them in the light of more recent information. Some few are alluvial but they are exceptional and of minor magnitude. As an example of such alluvial terraces I may mention those near the mouth of the Romsdal that are well seen from the Ak Hotel and which a Russian prince or other soldier merely endowed with military eyes might easily mistake for artificial earthworks erected for the defense of the valley. In this case, as in the others where the terraces are alluvial, the valley is a narrow one occupied by a relatively wide river loaded with recent glacial debris. It evidently filled the valley during the period of glacial recession. The ordinary wider valleys with the river that has cut a narrow channel through the widespread terrace flats display a different formation. Near the mouth of such valleys I have seen cuttings of more than 100 feet in depth through an unbroken terrace of most characteristic till with other traces rising above it. This is the ordinary constitution of the lower portions of most of the Scandinavian terraces. These terraces are commonly topped with quite a different stratum which at first I regarded as a subsequent alluvial or estuarine deposit but further examination suggested another explanation of the origin of some portions of this superficial stratum to which I shall refer hereafter. Such terraces prove a rise of sea or depression of land during the glacial epoch to the extent of 600 feet as a minimum while the well-known deposits of arctic shells at Moultrafon and the accompanying drift had led Professor Ramsey to estimate the probable amount of submergence during some part of the glacial period at about 2300 feet. It would be out of place here to reproduce the data upon which geologists have based their rather divergent opinions respecting the actual extent of the submergence of the western coast of north Europe. I'll agree that a great submergence occurred but differ only as to its extent their estimates varying between 1000 and 3000 feet. There is one important consideration that must not be overlooked. This is that if my view of the submarine origin of the till be correct the mere submergence of the land at the glacial period does not measure the difference between the depth of the sea at that and the present time, seeing that the deposits from the glaciers must have shallowed it very materially. It is only after contemplating thoroughly the present form of the granitic and metamorphic hills of Scandinavia, hills that are always angular when subjected only to sub aerial weathering, that one can form an adequate conception of the magnitude of this shallowing deposit. The rounding, shaving, grinding, planing, and universal abrasion everywhere displayed appear to me to justify the conclusion that if the sea were now raised to the level of the terraces, i.e. 600 feet higher than at present, the mass of matter abraded from the original Scandinavian mountains and lying under the sea would exceed the whole mass of mountain left standing above it. The first question suggested by reading Mr. Geeky's book was whether the terraces are wholly or partially formed of till, and more especially whether their lower portions are thus composed. This, as already stated, was easily answered by the almost unanimous reply of all the many Norwegian valleys I traversed. Any tourist may verify this. The next question was whether the same till extends below the sea. This was not so easily answered by the mains at my disposal, as I traveled hastily round the coast from Stavanger via the North Cape to the frontier of Russian Lapland in ordinary passenger steam packets, which made their stoppages to suit other requirements than mine. Still, I was able to land at many stations, and found, wherever there was a gently sloping strand at the mouth of an estuary, or of a valley whose river had already deposited its suspended matter, a common case hereabouts where so many rivers terminate in long estuaries, or open out into bag shaped lakes near the coast, and where the bottom had not been modified by secondary glaciation, that the receding tide displayed a sea bottom of till, covered with a thin stratum of loose stones and shells. In some cases, the till was so bare that it appeared like a stiff mud deposited but yesterday. At Buda, an arctic coast station on the north side of the mouth of the Salton Fjord, latitude 67 degrees 20 minutes, where the packets make a long halt, is a very characteristic example of this. A deposit of very tough till forming an extensive plain just beyond the sea level. The tide rises over this, and the waves break upon it, forming a sort of beach by washing away some of the finer material and leaving the stones behind. The ground being so nearly level, the reach of the tide is very great, and thus a large area is exposed at low tide. Continuous with this, and beyond the limit of high tide, is an extensive inland plain covered with coarse grass and weeds growing directly upon the surface of the original flat pavement of till. There is no river at Buda. The sea is clear, leaves no appreciable deposit, and the degree of denudation of the clay matrix of the till is very much smaller than might be expected. The limit of high water is plainly shown by a beach of shells and stones, but at low tide the ground over which the sea has receded is a bare and scarcely modified surface of till. I have observed the same at low water at many other arctic stations, in the Tromsåsund. There are shallows at some distance from the shore which are just covered with water at low tide. I landed and waited on these and found the bottom to consist of till covered with a thin layer of shells, odd fragments of earthenware, and other rubbish thrown overboard from vessels. It is evident that breakers of considerable magnitude are necessary for the loosening of this tough compact deposit, that it is very slightly, if at all, affected by the mere flow of running water. I specify these instances as characteristic and easy of verification, as the packets all stop at these stations, but a yachtsman sailing at leisure amidst the glorious coast scenery of the Arctic Ocean might multiply such observations a hundredfold by stopping wherever such strands are indicated in passing. I saw a multitude of these in places where I was unable to go ashore and examine them. A further question in this direction suggested itself on the spot. Viz, what is the nature of the banks which constitute the fishing grounds of Norway, Iceland, Newfoundland, etc.? They are submarine planes unquestionably. They must have a high degree of fertility in order to supply food for the hundreds of millions of voracious codfish, coalfish, hadox, halibut, etc., that peeple them. These large fishes all feed on the bottom, their chief food being maluska and crustacea, which must find, either directly or indirectly, some pasture of vegetable origin. These banks are, in fact, great meadows or feeding grounds for the lower animals which support the higher. From the Lefurten bank alone, 20 millions of codfish are taken annually, besides those devoured by the vast multitude of seabirds. Now, this bank is situated precisely where, according to the above stated view of the origin of the till, there should be a huge deposit. It occupies the Vestfjord, i.e., the opening between the mainland and the Lefurten Islands, extending from Maskenes to Lodingen on Hindu, just where the culminating masses of the Kjöln mountains must have poured their greatest glaciers into the sea by a westward course. And these glaciers must have been met by another stream pouring from the north, formed by the glaciers of Hindu and Sinyenjo. And both must have coalesced with a third flood pouring through the Ofurten Fjord, the Tisfjord, etc., from the mainland. The Vestfjord is about 60 miles wide at its mouth, and narrows northward till it terminates in the Ofurten Fjord, which forks into several branches eastward. A glance at a good map will show that here. According to my explanation of the origin of the till, there should be the greatest of all submarine plains of till, which the ancient Scandinavian glaciers have produced, and of which the plains of till I saw on the coast at Bodu, which lies just to the mouth of the Vestfjord, where the Salton Fjord flows into it, are but the slightly inclined continuation. Some idea of this bank may be formed from the fact that outside of the Lefudins, the sea is 100 to 200 fathoms in depth, that it suddenly shoals up to 16 or 20 fathoms on the east side of these rocks. And this shallow plain extends across the whole 50 or 60 miles between these islands and the mainland. It must not be supposed the fjords or inlets of Scandinavia are usually shallower than the open sea. The contrary is commonly the case, especially with the narrowest and those which run farthest inland. They are very much deeper than the open sea. If space permitted, I could show that the great Storgan bank opposite Alsund and Molde, where the Storfjord, Moldfjord, etc., were the former outlets of the glaciers, from the highest of all the Scandinavian mountains, and the several banks of Finmark, etc., from which, in the aggregate, are taken another 20 or 30 million of codfish annually, are all situated just where theoretically they ought to be found. The same is the case with the great bank of Newfoundland and the banks around Iceland, which are annually visited by large numbers of French fishermen from Dunkirk, Bologna, and other ports. Whenever the pack get halted over these banks during our coasting trip, we demonstrated their fertility by casting a line or two over the bulwark. No bait was required, merely a double hook with a flat shank attached to a heavy lead plummet. The line was sunk till the lead touched the bottom, a few jerks were given, and then a tug was felt. The line was hauled in with a codfish or halibut hooked, not inside the mouth, but externally by the gill plates, the back, the tail, or otherwise. The mere jerking of a hook near the bottom was sufficient to bring it in contact with some of the population. There is a very prolific bank lying between the North Cape and Nordkjön, where the Poisanger and Lachsfjords unite their openings. Here we were able, with only three lines, to cover the foredeck of the packet, with struggling victims in the course of short halts of 15 to 30 minutes. Not having any sounding apparatus by which to fairly test the nature of the sea bottom in these places, I cannot offer any direct proof that it was composed of till. By dropping the lead, I could feel it sufficiently to be certain that it was not rock in any case, but a soft deposit, and the marks upon the bottom of the lead so far as they went. Afforded evidence in favor of its clay character, a further investigation of this would be very interesting. But the most striking, I may say astounding evidence of the fertility of these banks, one which appeals most powerfully to the senses, is the marvelous colony of seabirds at Svæholt Klubben, the headlin between the two last named fjords. I dare not estimate the numbers that rose from the rocks and darkened the sky when we blew the steam whistle in passing. I doubt whether there is any other spot in the world where an equal amount of animal life is permanently concentrated. All these feed on fish, and an examination of the map will show why, in accordance with the above speculations, they should have chosen Svæholt Klubben as the best fishing ground on the arctic face of Europe. I am fully conscious of the main difficulty that stands in the way of my explanation of the formation of the till, vis that of finding sufficient water to float the ice, and should have given it up had I accepted Mr. Geeky's estimate of the thickness of the great ice sheet of the great ice age. He says on page 186 that the ice which covered the low grounds of Scotland during the early cold stages of the glacial epoch was certainly more than 2,000 feet in thickness, and it must have been even deeper than this between the mainland and the outer hebrides to cause such a mass to float. The sea around Scotland would require to become deeper than now, by 1,400 or 1,500 feet at least. I am unable to understand by what means Mr. Geeky measured this depth of the ice which covered these low grounds, except by assuming that its surface was level with that of the upper ice marks of the hills beyond. The following passage on page 63 seems to indicate that he really has measured it thus. Now the scratches may be traced from the islands and the coastline up to an elevation of at least 3,500 feet, so that ice must have covered the country to that height at least. In the highlands the tide of ice streamed out from the central elevations down all the main strats and glens, and by measuring the height attained by the smoothed and rounded rocks we are enabled to estimate roughly the probable thickness of the old ice sheet. But it can only be a rough estimate for so long a time has elapsed since the ice disappeared. The rain and frost together would have split up, and worn down the rocks of these highland mountains that much of the smoothing and polishing has vanished. But although the finer marks of the ice chisel have thus frequently been obliterated, yet the broader effects remain conspicuous enough. From an extensive examination of these, we gather that the ice could not have been less and was probably more than 3,000 feet thick in its deepest parts. Page 80 he says, bearing in mind the vast thickness reached by the Scotch ice sheet, it becomes very evident that the ice would flow along the bottom of the sea with as much ease as it poured across the land, and every island would be surmounted and crushed and scored and polished just as readily as the hills of the mainland were. Mr. Kiki describes the Scandinavian ice sheet in similar terms, but ascribes to it a still greater thickness. He says, page 404, the whole country has been molded and rubbed and polished by an immense sheet of ice, which could hardly have been less than 6,000 or even 7,000 feet thick. And he maintains that this spread over the sea and coalesced with the ice sheet of Scotland. My recollection of the Le Fouden Islands, which from their position afford an excellent crucial test of this question, led me to believe that their configuration presented a direct refutation of Mr. Kiki's remarkable inference, but a mere recollection of scenery being too vague, a second visit was especially desirable in reference to this point. The result of the special observations I made during this second visit fully confirmed the impression derived from memory. I found in the first place, that all along the coast from Stavanger to the Varanger Fjord, every rock near the shore is glaciated, among the thousands of low-lying ridges that peer above the water to various heights none near the mainland are angular. The general character of these is shown in the sketch of My Sea Serpent in the last edition of Through Norway with a knapsack. The rocks which constitute the extreme outlying limits of the Le Fouden group and which are between 60 and 70 miles from the shore, although many are illogically corresponding with those near the shore, are totally different in their conformation, as the sketch of three characteristic specimens plainly shows. Mr. Everest very aptly compares them to shark's teeth. Proceeding northward, these rocks gradually progress in magnitude. Until they become mountains of 3000 to 4000 feet in height, their outspread bases from large islands and the vest fjord gradually narrows. The remarkably angular and jagged character of these rocks, when weathered in the air, renders it very easy to trace the limits of glaciation on viewing them at a distance. The outermost and smallest rocks show from a distance no signs of glaciation. If submerged, the ice of the Great Ice Age was then enough to float over without touching them. If they stood above the sea, as at present, they suffered no more glaciation than would be produced by such an ice sheet as that of the paleocrystic ice recently found by Captain Nares on the north of Greenland. Progressing northward, the glaciation begins to become visible, running up to about 100 feet above the sea level on the islands, lying westward and southward of Ostwagen. Further northward along the coast of Ostwagen and Hindu, the level gradually rises to about 500 feet on the northern portion of Ostwagen and up to more than 1,000 feet on Hindu. While on the mainland it reaches 3,000 to 4,000 feet. A remarkable case of such variation, or descent of ice level as the ice sheet proceeded seaward, is Shona Tromsa. This small oblong island, latitude 69 degrees 40 minutes, on which is the capital town of Finnmark, lies between the mainland and the large mountainous island of Kvalo. With a long sea channel on each side, the Tromsund and the Sandesund, the total width of these two channels and the island itself being about 4 or 5 miles. The general line of glaciation from the mainland crosses the broad side of these channels and the island, which has evidently been buried and ground down to its present moderate height of 2 or 300 feet. Both of these channels are til-paved. On the east or inland side of the mountains near the coast are glaciated to their summits, are simply Rosh Mutanes, over which the reindeer of the Tromsdall lapse range and feed. On the west, the mountains are dark, pyramidal, non-glaciated peaks, with long vertical snow streaks marking their angular masses. The contrast is very striking when seen from the highest part of the island, and is clearly due to a decline in the thickness of the ice sheet in the course of its journey across this narrow channel. Speaking roughly from my estimation, I should say that this thinning or lowering of the limits of glaciation exceeds 500 feet between the opposite sides of the channel, which, allowing for the hill slopes, is a distance of about 6 miles. This very small inclination would bring a glacier of 3,000 feet in thickness on the shore down to the sea level in an outward course of 30 miles, or about half the distance between the mainland and the outer rocks of the Le Foudins shown in the engraving. I am quite at a loss to understand the reasoning upon which Mr. Geeky bases his firm conviction respecting the depth of the ice sheet on the low grounds of Scotland and Scandinavia. He seems to assume that the glaciers of the Great Ice Age had little or no superficial downslope corresponding to the inclination of the base on which they rested. I have considerable hesitation in attributing this assumption to Mr. Geeky, and would rather suppose that I have misunderstood him, as it is a conclusion so completely refuted by all we know of glacier phenomena and the physical laws concerned in their production. But the passages I have quoted and several others are explicit and decided. Those geologists who contend for the former existence of a great polar ice cap radiating outwards and spreading into the temperate zones might adopt this mode of measuring its thickness, but Mr. Geeky rejects this hypothesis, and shows by his map of the principal lines of glacial erosion in Sweden, Norway and Finland, that the glaciation of the extreme north of Europe proceeded from south to north, that the ice was formed on land, and proceeded seawards in all directions. I may add to this testimony that presented by the North Cape Sverholt Nordkin and the rest of the magnificent precipitous headlands that constitute the characteristic feature of the Arctic face of Europe. They stand forth defiantly as a phalanx of giant heralds proclaiming aloud the fallacy of this idea of southward glacial radiation, and in concurrence with the structure and striation of the great glacier troughs that lie between them, and the plained table land at their summits, they established the fact that during the greatest glaciation of the glacial epoch, the ice streams were formed on land, and flowed out to sea, just as they now do at Greenland or other parts of the world where the snowline touches or nearly approaches the level of the sea. All such streams must have followed the slope of the hillsides upon which they rested and down which they flowed, and thus the upper limits of glaciation afford no measure whatever of the thickness of the ice upon the low grounds of Scotland, or of any other glaciated country. As an example, I may refer to Mount Blanc. In climbing this mountain, the journey from the lower ice wall of the Glacier des Baisons up to the Bergschrund above the Grand Plateau is over one continuous ice field, the level of the upper part of which is more than 10,000 feet above its terminal ice wall. Thus, if we take the height of the striations or smoothings of the upper Neve above the low grounds on which the ice sheet rests, and adopt Mr. Geeky's reasoning, the lower ice wall of the Glacier des Baisons should be 10,000 feet thick. Its actual thickness, as nearly as I can remember, is about 10 or 12 feet. Every other known glacier presents the same testimony. The drawing of a Greenland Glacier opposite page 47 of Mr. Geeky's book shows the same under Arctic conditions, and where the ice wall terminates in the sea. I have not visited the Hebrides, but the curious analogy of their position to that of the Lefoudans suggests the desirability of similar observations to those I have made in the latter. If the ice between the mainland and the outer Hebrides was, as Mr. Geeky maintains, certainly more than 2,000 feet in thickness, and this stretched across to Ireland, besides uniting with the still thicker ice sheet of Scandinavia, these islands should all be glaciated, especially the smaller rocks. If I am right, the smaller outlying islands, though south of Barra, should, like the corresponding rocks of the Lefoudans, display no evidence of having been overswept by a deep mer de glace. I admit the probability of an ice sheet extending as Mr. Geeky describes, but maintain that it thinned out rapidly seaward, and there became a mere ice flow, such as now impedes the navigation of smith's sound and other portions of the Arctic Ocean, the Orkneys and Shetlands, with which I am also unacquainted, must afford similar crucial instances, always taking into account the fact that the larger islands may have been independently glaciated by the accumulations due to their own glacial resources. It is the small rocks standing at considerable distance from the shores of larger masses of land that supply the required test conditions. From the above it will be seen that I agree with Mr. Geeky in regarding the till as a moraine profonde, but differ as to the mode and place of its deposition. He argues that it was formed under glaciers of the thickness he describes, while their whole weight rested upon it. This appears to me to be physically impossible. If such glaciers were capable of eroding solid rocks, the slimy mud of their own deposits could not possibly have resisted them. The only case where this might have happened is where a mountain wall has blocked the further downward progress of a glacier, or in pockets, or steep hollows which a glacier might have bridged over and filled up. But such pockets are by no means the characteristic localities of till, though the till of Switzerland may possibly show examples of the first case. The great depth of the inland lakes of Norway, their bottoms being usually far below that of the present sea bottom, is in direct contradiction of this. They should, before all places, be filled with till, if the till were a ground moraine formed on land, but all we know of them confirms the belief that the glaciers deepened them by erosion instead of shallowing them by deposition. Mr. Geeky's able defense of Ramsay's theory of lake base and erosion is curiously inconsistent with his arguments in favor of the ground moraine. I fully concur with Mr. Geeky's arguments against the iceberg theory of the formation of the till. This, I think, he has completely refuted. Before concluding, I must say a few words on those curious lenticular bends of sand and gravel in the till which appear so very puzzling. A simple explanation is suggested in connection with the above sketched view of the formation of the till. All glaciers, whether in arctic or temperate climates, are washed by streamlets during summer, and these commonly terminate in the form of a stream or cascade pouring down a moulin, a well bored by themselves and reaching the bottom of the glacier. Now what must be the action of such a downflow of water upon my supposed submarine bed of till, just grazing the bottom of the glacier? Obviously, to wash away the fine clay particles and leave behind the coarser sand or gravel. It must form just such a basin or lenticular cavity as Mr. Geeky describes. The oblong shape of these, their longer axis coinciding with the general course of the glacier, would be produced by the onward progress of the moulin. The accordance of their other features with this explanation will be seen on reading Mr. Geeky's description, page 18, 19, etc. The general absence of marine animals and their occasional exceptional occurrence in the intercalated beds is just what might be expected under the conditions I have sketched. In the gloomy sub-glacial depths of the sea, drenched with continual supplies of fresh water and cooled below the freezing point by the action of salt water in the ice, ordinary marine life would be impossible, while on the other hand, any recession of the glacial limit would restore the conditions of arctic animal life, to be again obliterated with the renewed outward growth of the floating skirts of the inland ice mantle. But I must now refrain from the further discussion of these and other collateral details, but hope to return to them in another paper. In Through Norway with Ladies, I have touched lightly upon some of these and have more particularly described some curious and very extensive evidences of secondary glaciation that quite escaped my attention on my first visit, and which too have been equally overlooked by other observers. In the above, I have endeavored to keep as nearly as possible to the main subject of the origin of the till and the character of the ancient ice sheet. End of section 16