190 M. H. Herwig on the Number and Weight of the 



the equator would continue so long as the alternate glaciation 

 of the two hemispheres continued. 



This lowering of the temperature of the equator during the 

 severest part of the glacial epoch will help to explain the former 

 existence of glaciers in intertropical regions at no very great 

 elevation above the sea-level, evidence of which appears recently 

 to have been found by Mr. Belt and others. 



XXIV. On the Number and Weight of the Molecules of^Ether 

 contained in Electric Conductors. By Hermann Herwig*. 



IN the following I will briefly indicate a way in which, cer- 

 tain hypotheses presupposed, very remarkable explanations 

 of the relations of the aether might possibly be reached. 



I start from the comparison of the expressions, on the one 

 hand, for the thermal effect of a galvanic current, and, on the 

 other hand, for the vis viva represented therein at any moment 

 by the motion of the electric particles. I may mention before- 

 hand that it is quite immaterial of what kind we suppose the 

 motion of the electrical masses to be. Even a not uniform, 

 somehow oscillating motion would only introduce into the cal- 

 culation additional simple factors which would be quite insigni- 

 ficant for the final result. Such motions will therefore be left 

 out of consideration. 



This presupposed, and holding fast the notion of only one 

 fluid, let e be, in electrostatic measure, the quantity of electricity 

 in motion in 1 rnillim. length of the conductor, and v its velo- 

 city, the unit of time being the second. Then, in mechanical 

 measure, the current-intensity is ev. If, further, also expressed 

 in mechanical measure, R is the resistance of 1 millim. of the 

 conductor, and L millim. the length of the latter, in it there is 

 produced in 1 second, according to Joule's law, a quantity of 

 heat which has in mechanical measure the expression 



eVRL. (I.) 



The motion of the electric masses in this current represents a 

 permanently constant vis viva of the magnitude 



rJ ■;.• of) 



where the masses are reckoned in the usual weights ; therefore 



e 



- signifies the quantity of electricity in milligrammes in the unit 



of length. 



* Translated from a separate impression, communicated by the Author, 

 from Poggendorff's Annalen, vol. cl. pp. 381-385. 



