Forbes and Agassiz

Abstract

In the review of Dr. Tyndall's book on the “Forms of Water” which appeared in NATURE, vol. vii. p. 400, the following words occur:—“But surely it was not unnecessary to rake up again the Forbes-Rendu controversy, nor to renew the claims of Agassiz and Guyot.” Mr. Alexander Agassiz takes exception to this (see NATURE, vol. viii. p. 24) and makes the following assertions:—That when a guest of Agassiz on the glacier of the Aarin 1841, Forbes returned the hospitality of Agassiz “by appropriating what he could” from the work of the latter, and “misrepresenting the nature of his intercourse with Agassiz.” This refers to a matter of facts and may be proved or disproved by the facts. It refers to an attack made upon Forbes in 1842, which was immediately answered by him in a manner that left no room for further discussion. I must necessarily be brief in stating the facts. They may be found fully detailed in the Edin. New Phil. Journal 1843, or in the “Life and Letters of James David Forbes, 1873.” They are as follows:—In 1841 Forbes enjoyed the pleasure of a visit to Agassiz on the Unteraar Glacier. On the first day of their sojourn (August 9), their only companion was Mr. Heath, of Cambridge. They were afterwards joined by friends of Agassiz. On this first day Forbes pointed out to Agassiz the veined structure of the ice. Agassiz had spent five summers studying the glaciers (see Mr. Alexander Agassiz' letter in NATURE), but he replied “that it must be a superficial phenomenon, that he had on a previous occasion noticed such markings, and that they were caused by the sand of the moraines causing channels of water to run.” Forbes showed him that the structure was general, even in the body of the glacier. Agassiz expressed a doubt “whether the structure had not been superinduced since the previous year.” Forbes afterwards showed him that in a crevasse three or four years old the markings extended across the crevasse and were visible in continuation from one side to the other. Further, Forbes insisted upon its intimate connection with the theory of glaciers. When in the ensuing winter M. Desor wrote to Prof. Forbes denying his claims to the discovery, the latter sent him a statement of the above facts, begging that M. Agassiz should state whether they were correct or not. M. Agassiz wrote an answer to this letter. He does not deny a single one of the facts supplied by Forbes in connection with the observations of August 9. This letter was printed and circulated by M. Agassiz. Furthermore, when these facts were published by Forbes, even then M. Agassiz did not deny any of them. Moreover, Mr. heath, the only other witness, gives his evidence in support of the accuracy of the above facts (see “Life of Forbes,” Appendix B, Extract L). Other friends of Agassiz, who joined them afterwards, wrote to Forbes stating their belief that to him alone belonged the discovery. After leaving the Aar glacier Forbes extended his observations. He showed (1), that the structure was common to most, if not all, glaciers (see “Forbes' Life,” p. 550, note); (2), that this was the cause of the sand lying its lines (“Life,” p. 548); (3), that this was also the cause of the supposed horizontal stratification of the terminal face of some glaciers (Royal Soc. Edin., 1841, Dec. 6); (4), he showed that these blue markings were the outcroppings of blue ice that formed lamellar surfaces in the interior of the glacier; (5), he actually determined the shape of these surfaces in the case of the Rhone glacier (R. S. E., 1841, Dec. 6); (6), he remarked that “the whole phenomenon has a good deal the air of being a structure induced perpendicular to the lines of greatest pressure,” though he did not assert the statement to be general. This was in 1841. In later years he extended these observations. I have said enough to prove (1), that although Agassiz carried with him “a geologist, a microscopic observer, a secretary, a draughtsman, and many workmen,” and though he had spent five summers studying the glaciers, he did not see these markings (or at any rate recognise them as a structure of the ice) until Forbes showed them to him; and (2), that Forbes recognised this structure as an important “indication of an unknown cause” (“Occasional Papers,” p. 4), and worked out the subject thoroughly.