intention of Agassiz had been to embody the whole in a publication, the first part of which should contain the glacial system of Agassiz; the second the Alpine erratics, by Guyot; while the third and final portion, by E. Desor, should treat of the erratic phenomena outside of Switzerland. The first volume alone was completed. Unlooked for circumstances made the continuation of the work impossible, and the five thousand specimens of the erratic rocks of Switzerland collected by Professor Guyot, in preparation for his part of the publication, are now deposited in the College of New Jersey, at Princeton. In the following summer of 1839 Agassiz took the chain of Monte Rosa and Matterhorn as the field of a larger and more systematic observation. On this occasion, the usual party consisting of Agassiz, Desor, M. Bettanier, an artist, and two or three other friends, was joined by the geologist Studer. Up to this time he had been a powerful opponent of Agassiz's views, and his conversion to the glacial theory during this excursion was looked upon by them all as a victory greater than any gained over the regions of ice and snow. Some account of this journey occurs in the following letter. LOUIS AGASSIZ TO SIR PHILIP EGERTON. NEUCHATEL, September 10, 1839. . . .Under these circumstances, I thought I could not do better than to pass some weeks in the solitude of the high Alps; I lived about a fortnight in the region of the glaciers, ascending some new field of ice every day, and trying to scale the sides of our highest peaks. I thus examined in succession all the glaciers descending from the majestic summits of Monte Rosa and the Matterhorn, whose numerous crests form a most gigantic amphitheatre, which lifts itself above the everlasting snow. Afterward I visited the sea of ice which, under the name of the glacier of Aletsch, flows from the Jungfrau, the Monch, and the Eiger toward Brieg; thence I went to the glacier of the Rhone, and from there, establishing my headquarters at the Hospice of the Grimsel, I followed the glacier of the Aar to the foot of the Finsteraarhorn. There I ascertained the most important fact that I now know concerning the advance of glaciers, namely, that the cabin constructed by Hugi in 1827, at the foot of the Abschwung, is now four thousand feet lower down. Slight as is the inclination of the glacier, this cabin has been carried on by the ice with astonishing rapidity, and still more important is it that this rapidity has been on the increase; for in 1830 the cabin was only some hundred feet from the rock, in 1836 it had already passed over a distance from [word torn away] of two thousand feet, and in the last three years it has again doubled that distance. Not only have I confirmed my views upon glaciers and their attendant phenomena, on this new ground, but I have completed my examination of a number of details, and have had besides the satisfaction of convincing one of my most