MEMOIR OF GUYOT. 697 



Humboldt. His address at the Humboldt Commemoration of the 

 American Geographical Society, in 1859, was a beautiful tribute to this 

 model student of nature.* 



The five years of study at the Berlin University terminated with an 

 examination which brought him the degree of Doctor of Philosophy. 

 His graduating thesis, written in Latin, as was then the rule, was on 

 "The Natural Classification of Lakes." 



To Paris, the Pyrenees, Italy, etc., 1835 fo 1859. — From Berlin, Guyot, in 

 his twenty eighth year — June of 1835 — went to Paris to take charge of 

 the education of the sons of Count de Pourtal^sGorgier, and continued 

 with the family four years. Letters of introduction from Humboldt led 

 to much intercourse with Brongniart and other savants of the great city. 

 For the summer he accompanied the family to Eaux Bonnes, in the 

 Pyrenees. While there he made ascents of the higher peaks and took 

 excursions in various directions — to the amphitheater of Gavarnie, to 

 the borders of Spain by the Pout d'Espagne and the pass beyond, to 

 the valley of the Eaux Chaudes, etc. — in order to study the features 

 and flora, and compare the mountains in these respects with the Alps. 

 In the autumn he went with his pupils to Belgium, Holland, and the 

 Ehiue to study the characteristic features of these countries. The fol- 

 lowing year he visited Pisa, and there, besides enjoying the new scenes, 

 made various barometrical measurements, determining the elevation of 

 the observatory at Florence and of other points. 



Trip to the glaciers in 1838. — In the spring of 1838 Agassiz found 

 Guyot still at Paris. During the summer preceding Agassiz had 

 startled the scientific world by his declarations as to a Universal Gla- 

 cial Era, contained in a paper read before the Helvetic Society of Nat- 

 ural Sciences assembled at Neuchatel. His work in 1837 — prompted 

 in 1836 by Charpentier's discoveries proving the fact of a former epoch 

 of immense glaciers in Switzerland — had led him to the bold conclu- 

 sion, and he was full of his new idea when he met his old companion. 

 He urged Guyot, who hesitated at accepting his views without exami- 

 nation, to study the facts, and obtained the promise that he would visit 

 the glaciers that summer. 



In his memoir of Agassiz, Guyot states that his six weeks of investi- 

 gation that season in the Central Alps (nearly two years before Agas- 

 siz commenced his investigation on the Glacier of the Aar) were fruit- 

 ful beyond expectation. He says that from the examination of the 

 glaciers of the Aar, Rhone, Gries, Brenva, and others, he learned (1) 

 the law of the moraines; (2) that of the more rapid flow of the center 

 of the glacier than the sides; (3) that of the more rapid flow of the top 

 than the bottom ; (4) that of the laminated or ribboned structure (" blue 

 bands"); and (5) that of the movement of the glacier by a gradual mo- 

 lecular displacement, instead of by a sliding of the ice-mass, as held by 

 de Saussure. 



* Journal of the American Geographical Society, October, 1859; vol. i, p. 242. 



