PHYSICS, EIGHTEENTH CENT. MAGNETISM. 339 



poles. This was the case with Musschenbroeck, Hawksbee, and Taylor, 

 and the real laws remained unknown until the classical investigations 

 of Coulomb, which were made by means of the torsion balance, the 

 general principle and construction of which have been already ex- 

 plained (page 335). Coulomb thus demonstrated that the magnetic 

 forces vary inversely as the squares of the distances. He also inves- 

 tigated the distribution of the magnetism in a bar, the effect of heat 

 on magnets, and many other subjects relating to the magnetic forces. 

 The torsion balance was used by Coulomb in all such inquiries with 

 singular advantage. Canton, Duhamel, Ritterhouse, Scoresby, .^Epinus, 



222 



