On the History of Conservation of Energy. 215 



4thly. We have seen, in fact, that, so far as the Alpine lakes ge- 

 nerally are concerned, and as regards that of Geneva in particular, 

 their position has been determined along a line of overthrow, or re- 

 versal of the strata. We have seen that the form of the Lake of 

 Geneva was caused, in the eastern part, by the curvature of the 

 mountains on its southern banks, and in its western part by its 

 parallelism with the great anticlinal axis which traverses Switzer- 

 land. 



Finally, we have remarked that the greatest depth of the Lake 

 of Geneva lies along the line of reversed strata which occurs at 

 the junction of the Alps with the plain. Consequently the sort 

 of basin to which this lake belongs is not the result of a cause 

 acting on the surface of the globe, but is what may be termed 

 a volcanic effect (that word being used in the sense assigned to 

 it by Humboldt), viz. the influence exerted by the interior forces 

 of a planet on its external crust in the different stages of its 

 cooling. Accept, &c. &c, 



Alphonse Favre. 



P.S. — Since the dispatch of my previous letter, I have read 

 with extreme interest your Address to the Geographical Society 

 of London, of the 23rd May, 1864, with which you have been 

 so good as to favour me. I find in that address a clear and 

 precise summary of the state of the question, and valuable 

 evidences derived from many parts of the world. I perceive in 

 it, again, with pleasure that we are of the same opinion respect- 

 ing the excavation of lakes and the erosion of valleys by glaciers. 

 You make use of several highly important arguments against 

 that view of the question, and you have already developed the 

 idea on which I have dwelt — viz., that the form of the Lake of 

 Geneva is divergent from the direction of the most powerful or 

 central portion of the glacier of the Rhone, which advanced from 

 the Valais in the direction of Yverdun, following what I have 

 termed the median line. 



Pray, Sir, oblige me by inserting this remark at the end of 

 my letter of the 12th of January. — A. F. 



Geneva, January 22, 1865. 



XXXI. On the History of Conservation of Energy, and of its 

 application to Physics. By Professor Bohn*. 



IT is an old experience, that great and fruitful ideas make their 

 entrance into the world neither suddenly nor in a state of 

 complete perfection ; they generally require a certain time of de- 



* Communicated by the Author. 



