in the Memoirs of the Natural History Society of Neuchatel, as well as his paper on the fossil Echini belonging to the Neocomian group of the Neuchatel Jura, accompanied by figures. Not long after, he published in the Memoirs of the Helvetic Society his descriptions of fossil Echini peculiar to Switzerland, and issued also the first number of a more extensive work, "Monographie d'Echinodermes." During this year he received a new evidence of the sympathy of the English naturalists, in the Wollaston medal awarded to him by the London Geological Society.

The summer of 1836 was an eventful one for Agassiz,--the opening, indeed, of a new and brilliant chapter in his life. The attention of the ignorant and the learned had alike been called to the singular glacial phenomena of movement and transportation in the Alpine valleys. The peasant had told his strange story of boulders carried on the back of the ice, of the alternate retreat and advance of glaciers, now shrinking to narrower limits, now plunging forward into adjoining fields, by some unexplained power of expansion and contraction. Scientific men were awake to the interest of these facts, but had considered them only as local phenomena. Venetz and Charpentier were the first to detect their wider significance. The former traced the ancient limits of the Alpine glaciers as defined by the frame-work of debris or loose material they had left behind them; and Charpentier went farther, and affirmed that all the erratic boulders scattered over the plain of Switzerland and on the sides of the Jura had been thus distributed by ice and not by water, as had been supposed.

Agassiz was among those who received this hypothesis as improbable and untenable. Still, he was anxious to see the facts in place, and Charpentier was glad to be his guide. He therefore passed his vacation, during this summer of 1836, at the pretty town of Bex, in the valley of the Rhone. Here he spent a number of weeks in explorations, which served at the same time as a relaxation from his more sedentary work. He went expecting to confirm his own doubts, and to disabuse his friend Charpentier of his errors. But after visiting with him the glaciers of the Diablerets, those of the valley of Chamounix, and the moraines of the great valley of the Rhone and its principal lateral valleys, he came away satisfied that a too narrow interpretation of the phenomena was Charpentier's only mistake.

During this otherwise delightful summer, he was not without renewed anxiety lest he should be obliged to suspend the publication of the Fossil Fishes for want of means to carry it on. On this account he writes from Bex to Sir Philip Egerton in relation to the sale of his original drawings, the only property he possessed. "It is absolutely impossible," he says, "for me to issue even another number until this sale is effected. . .I shall consider myself more than repaid if I receive, in exchange for the whole collection of drawings, simply what I have expended upon them, provided I may keep those which have yet to be lithographed until that be done."

Sir Philip made every effort to effect a sale to the British Museum. He failed at the moment, but the collection was finally purchased and presented to the British Museum by a generous relative of his own, Lord Francis Egerton. In the mean time, Sir Philip and Lord Cole, in order to make it possible for Agassiz to retain the services of Mr. Dinkel, proposed to pay his expenses while he was drawing such specimens from their own collections as were needed for the work. These drawings were, of course, finally to remain their own property.

During his sojourn at Bex, Agassiz's intellect and imagination had been deeply stirred by the glacial phenomena. In the winter of 1837, on his return to Neuchatel, he investigated anew the slopes of the Jura, and found that the facts there told the same story. Although he resumed with unabated ardor his various works on fishes, radiates, and mollusks, a new chapter of nature was all the while unfolding itself in his fertile brain. When the Helvetic Association assembled at Neuchatel in the following summer, the young president, from whom the members had expected to hear new tidings of fossil fishes, startled them by the presentation of a glacial theory, in which the local erratic phenomena of the Swiss valleys assumed a cosmic significance. It is worthy of remark here that the first large outlines in which Agassiz, when a young man, planned his intellectual work gave the key-note to all that followed. As the generalizations on which all his future zoological researches were based, are sketched in the Preface to his "Poissons Fossiles," so his opening address to the Helvetic Society in 1837 unfolds the glacial period as a whole, much as he saw it at the close of his life, after he had studied the phenomena on three continents. In this address he announced his conviction that a great ice-period, due to a temporary oscillation of the temperature of the globe, had covered the surface of the earth with a sheet of ice, extending at least from the north pole to Central Europe and Asia. "Siberian winter," he says, "established itself for a time over a world previously covered with a rich vegetation and peopled with large mammalia, similar to those now inhabiting the warm regions of India and Africa. Death enveloped all nature in a shroud, and the cold, having reached its highest degree, gave to this mass of ice, at the maximum of tension, the greatest possible hardness." In this novel presentation the distribution of erratic boulders, instead of being classed among local phenomena, was considered "as one of the accidents accompanying the vast change occasioned by the fall of the temperature of our globe before the commencement of our epoch."

This was, indeed, throwing the gauntlet down to the old expounders of erratic phenomena upon the principle of floods, freshets, and floating ice. Many well-known geologists were present at the meeting, among them Leopold von Buch, who could hardly contain his indignation, mingled with contempt, for what seemed to him the view of a youthful and inexperienced observer. One would have liked to hear the discussion which followed, in special section, between Von Buch, Charpentier, and Agassiz. Elie de Beaumont, who should have made the fourth, did not arrive till later. Difference of opinion, however, never disturbed the cordial relation which existed between Von Buch and his young opponent. Indeed, Agassiz's reverence and admiration for Von Buch was then, and continued throughout his life, deep and loyal.

Not alone from the men who had made these subjects their special study, did Agassiz meet with discouragements. The letters of his beloved mentor, Humboldt, in 1837, show how much he regretted that any part of his young friend's energy should be diverted from zoology, to a field of investigation which he then believed to be one of theory rather than of precise demonstration. He was, perhaps, partly influenced by the fact that he saw through the prejudiced eyes of his friend Von Buch. "Over your and Charpentier's moraines," he says, in one of his letters, "Leopold von Buch rages, as you may already know, considering the subject, as he does, his exclusive property. But I too, though by no means so bitterly opposed to new views, and ready to believe that the boulders have not all been moved by the same means, am yet inclined to think the moraines due to more local causes."

The next letter shows that Humboldt was seriously anxious lest this new field of activity, with its fascinating speculations, should draw Agassiz away from his ichthyological researches.

HUMBOLDT TO AGASSIZ.

BERLIN, December 2, 1837.

I have this moment received, my dear friend, by the hand of M. de Werther, the cabinet minister, your eighth and ninth numbers, with a fine pamphlet of text. I hasten to express my warm thanks, and I congratulate the public on your somewhat tardy resolution to give a larger proportion of text. One should flatter neither the king, nor the people, nor one's dearest friend. I maintain, therefore, that no one has told you forcibly enough how the very persons who justly admire your work, constantly complain of this fragmentary style of publication, which is the despair of those who have not the leisure to place your scattered sheets where they belong and disentangle the skein.* (* Owing to the irregularity with which he received and was forced to work up his material, Agassiz was often either in advance or in arrears with certain parts of his subject, so that his plates and his text did not keep pace with each other, thus causing his readers much annoyance.)

I think you would do well to publish for a while more text than plates. You could do this the better because your text is excellent, full of new and important ideas, expressed with admirable clearness. The charming letter (again without a date) which preceded your package impressed me painfully. I see you are ill again; you complain of congestion of the head and eyes. For mercy's sake take care of your health which is so dear to us. I am afraid you work too much, and (shall I say it frankly?) that you spread your intellect over too many subjects at once. I think that you should concentrate your moral and also your pecuniary strength upon this beautiful work on fossil fishes. In so doing you will render a greater service to positive geology, than by these general considerations (a little icy withal) on the revolutions of the primitive world; considerations which, as you well know, convince only those who give them birth. In accepting considerable sums from England, you have, so to speak, contracted obligations to be met only by completing a work which will be at once a monument to your own glory and a landmark in the history of science. Admirable and exact as your researches on other fossils are, your contemporaries claim from you the fishes above all. You will say that this is making you the slave of others; perfectly true, but such is the pleasing position of affairs here below. Have I not been driven for thirty-three years to busy myself with that tiresome America, and am I not, even yet, daily insulted because, after publishing thirty-two volumes of the great edition in folio and in quarto, and twelve hundred plates, one volume of the historical section is wanting? We men of letters are the servants of an arbitrary master, whom we have imprudently chosen, who flatters and pets us first, and then tyrannizes over us if we do not work to his liking. You see, my dear friend, I play the grumbling old man, and, at the risk of deeply displeasing you, place myself on the side of the despotic public. . .

With reference to the general or periodical lowering of the temperature of the globe, I have never thought it necessary, on account of the elephant of the Lena, to admit that sudden frost of which Cuvier used to speak. What I have seen in Siberia, and what has been observed in Captain Beechey's expedition on the northwest coast of America, simply proves that there exists a layer of frozen drift, in the fissures of which (even now) the muscular flesh of any animal which should accidentally fall into them would be preserved intact. It is a slight local phenomenon. To me, the ensemble of geological phenomena seems to prove, not the prevalence of this glacial surface on which you would carry along your boulders, but a very high temperature spreading almost to the poles, a temperature favorable to organizations resembling those now living in the tropics. Your ice frightens me, and gladly as I would welcome you here, my dear friend, I think, perhaps, for the sake of your health, and also that you may not see this country,