66 Mr William Petrie on the Application of 



tion, in terms of the great centre and medium of comparison, 

 Mechanical Force, 



Table of the Relative and Absolute Powers of various Galvanic 

 Arrangements^ 8fc., shewing the Electric Current circulated by 

 them, after the surfaces of the elements have been in action for 

 several hours with continuous supplies of liquids, the Tempera- 

 ture being 70°. 



These data have been found very useful in determining 

 the best proportions of batteries for practical purposes. 



On the Application of Electricity and Heat, as Moving Powers. 

 By Mr William Petrie. Communicated by the Author. 



From the dynamic equivalent of electricity already given 

 (p. 64), we can infer an important fact, that one horse power 

 is the theoretic or absolute dynamic force possessed by a cur- 



