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XVII. On the Rotation of Hollow Spheres of Metal by Heat. 

 By G. Gore, Esq.* 



IN the Supplementary Number of the Philosophical Magazine, 

 June 1858 (sec also the Number for February 1859), I 

 described an apparatus for producing rotation of tubes and hol- 

 low spheres of metal by means of heat of electric conduction- 

 resistance, the moving body being placed upon a horizontal 

 metallic railway, and the heat being produced by passing a pow- 

 erful electric current from one rail through the ball or tube to 

 the other by means of their points of mutual contact. 



Since that period I have further considered the conditions of 

 the phfenomeuon referred to, and have constructed the following 

 apparatus for producing similar motion by means of ordinary 

 heat. 



A and A', fig. 1, is a massive circular ring or railway, com- 



Fig. 1. (Scale ith.) 



posed of metallic copper f, and cast in one piece (seen in section, 

 fig. 2j ; the outer rail. A, is 10 inches in diameter, and the inner 

 one. A', is 6 inches; the height of the outer rail is li inch, 

 and that of the inner one is y'^th of an inch less ; the distance 



* Communicated by the Author. 



t The ring contained a Uttle brass in its composition, to enable it to be 

 more readily melted and east. 



