XXVTU PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



I am not aware that Dr. Thomson wrote anything bearing directly 

 on geology. His collection of minerals, now in possession of his 

 nephew Dr. R. D. Thomson, is, I understand, one of the most com- 

 plete ever made ; but his original researches were entirely chemical. 

 His contributions to that branch of science were numerous, and 

 justly obtained for him that high reputation which he lived so many- 

 years to enjoy. I may also add that he was the first convert to 

 Dalton's Atomic Theory, and one of its most zealovis promoters. 

 As a journalist, also, science is indebted to him for the esta- 

 blishment of the Annals of Philosophy, which still continues, under 

 the name of the ' Philosophical Magazine,' and under the able 

 direction of Mr. Richard Taylor, to be one of our leading scientific 

 journals. 



The number of geological subjects, Gentlemen, which present 

 themselves for discussion is become so great, that an appropriate 

 selection for an occasion like the present is not without its difl&culty. 

 The principal subject on which I shall address you is one which 

 has been suggested to me, independently, by several of the most di- 

 stinguished members of our Society. You are all aware that M. 

 Elie de Beaumont put forth many years ago his theorj^ of the paral- 

 lelism of mountain chains of contemporaneous elevation. His ori- 

 ginal views have been expanded from time to time, and have received 

 their most complete development in a work very recently published 

 by him, under the title oi Notice sur les Systemes de Montaynes*. 

 It contains a large amount of mathematical investigation, which 

 renders a great portion of it inaccessible to readers who do not 

 possess a thorough acquaintance with geometry ; and the general 

 arrangement of the work, though well calculated to give a complete 

 development of the author's views, is such as to make it sometimes 

 difficult to appreciate the exact value of his evidence in support of 

 them without a careful examination of numerovis details. The whole 

 is worked out with great ingenuity, a perfect acquaintance with the 

 mathematics of the subject, and with that unflinching perseverance 

 and honesty, if I may so speak, which have left none of the intri- 

 cacies of his problem without a thorough investigation. The theory 

 which he maintains exercises, as you are aware, a wide influence over 

 the rising geologists of France, and has also been accepted to a con- 

 siderable extent by other continental geologists ; and whatever may 

 be the degree in which it may have a claim to our confidence, every 

 geologist ought to be acquainted with it, if he would make himself 

 fully conversant with the existing state of the science. I have 

 thought, therefore, that I could not on the present occasion render 

 a more acceptable service to the Society than by laying before you 

 as complete an analysis of M. E. de Beaumont's work as I am able 

 to make, and such as shall not only make you acquainted with the 

 conclusions of his theory, but may also enable you to appreciate for 

 yourselves the evidence on which it rests. 



I must first request your attention to a few preliminary points. 

 * Three vols. 12mo. Paris 1852. 



