NATURAL HISTORY OF GENEVA. 



155 



have confirmed tbeiii, only rendering tbem somewhat more exact. Then 

 followed their work upon the increase of temperature in the artesian wells 

 of Preguy. It was known that heat increased with depth in the excava- 

 tions of mines, but the observations of Augaste de la Kiveand Marcet 

 gave the progression of temperature to 050 feet, in a determined locality. 

 I had the satisfaction at this time to make a series of experiments with 

 De la Eive upon the conductibility of heat in different woods. We estab- 

 lished a fact which finds application in vegetable physiology, namely, 

 that heat passes less easily in the transversal than in the longitudinal 

 direction of the fibers. While mentioning this investigation 1 cannot 

 resist the pleasure of dwelling upon the extreme modesty and amiability 

 of De la Rive as a collaborator. jSTotwithstanding his great talent, he 

 announced his opinions and accepted those of others with a charming 

 simplicity and absence of self-assertion. As he appeared to me in his 

 youth, so he continued even to the close of his life, when, weary and ill, 

 he made with our young secretary, M. Edouard Sarasin, some original 

 researches upon electricity in rarefied gases. 



Ampere and Faraday did much to excite De la Rive to the study of 

 electrical phenomena ; but from the constitution of his mind I am 

 induced to believe that the desire to establish firmly an important law, 

 namely, that chemical phenomena are the source of electricity, was tlie 

 principal motive which led him in this direction. How he succeeded in 

 establishing this law, what ingenious contrivances he invented to prove 

 it, and the multiplied consequences he deduced from his experiments, I 

 cannot as a naturalist, and unacquainted with the details of physics, 

 adequately describe. One of our colleagues, much better quahfied, will 

 refer to them particularly in an article upon De la Rive, which will be 

 inserted in the Archives des Sciences. I have read a few pages of this 

 article, and although the publication of it may not be entire, the follow- 

 ing paragraphs will undoubtedly be retained, at least in their general 

 import : 



" In a long series of memoirs, De la Rive has passed in review most of 

 the properties of the pile, and the effects produced by currents, con- 

 tributing thus in a great degree to determine the laws and to throw 

 light upon these complex phenomena, which were still very little under- 

 stood at the beginning of the century. 



" In the course of these great researches, the subject which most 

 attracted his interest and efforts was the chemical theory of the pile. 

 The cause of the disengagement of electricity in this apparatus had 

 been attributed by its illustrious inventor to the contact of the two dif- 

 ferent metals which form an essential part of it. The chemical action 

 exercised by the liquids upon the metals, was considered by Volta and 

 his i)artisans as an accessory phenomenon, hardly as an effect of the 

 current. But in i)roportion as the numerous relations of electricity and 

 chemical actions were more and more exposed, the opposite theory com- 

 menced to gain ground. De la Rive for manv veais was one of its most 



