160 .Proceedings. 



Societies on the Continent and in America, as well as 

 corresponding member of the Institute of France. In 

 1880 he founded a meteorological observatory at Colmar, 

 and wrote several papers on the meteorology of the Rhine 

 Valley. 



"His business as manager of works not only brought 

 directly under his notice practical questions of economical 

 transmission of power and of the mode of action of lubri- 

 cants, but also placed at his disposal machinery for making 

 experiments on a large scale, of which he took advantage 

 with great industry and exceptional skill. Hirn's publica- 

 tions have been numerous and very diverse both in manner 

 and method, dealing both with experiment and with theo- 

 retical conclusions. Besides his important Treatise on the 

 Mechanical Theory of Heat, I may mention the memoirs 

 on Thermodynamics, on the theory of the gyroscope, on 

 the conditions of equilibrium and probable nature of Saturn's 

 Rings, on the optical properties of flame and the tempera- 

 ture of the sun, and a popular discussion of the conditions 

 of life on Saturn, as well as a work on the philosophical 

 and metaphysical consequences of Thermodynamics. Hirn 

 not only maintained very strongly his opinions on the 

 sciences which he studied, but he also expresses his views 

 on more general matters when they arise in connection 

 with the subject under consideration. 



" He protests against the common practice of stating a 

 metaphysical proposition, and claiming that it is proved by 

 some physical experiments ; especially against representing 

 that, in proving the falsity of the doctrine of imponderables, 

 the modern theory of thermodynamics has placed it beyond 

 doubt that the phenomena of heat, electricity, and magne- 

 tism are to be, of necessity, considered as movements of 

 ponderable matter, with deductions that force has no real 

 existence in the Universe, that gravitation is but the con- 

 sequence of some invisible motion of atoms in space, and 



