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XLV. Description of a Rotative Thermo-magnetical Experi- 

 ment. By Mr. William Sturgeon. 



To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, 

 ITAVING promised in a former paper to communicate to 

 •*■ -■• your readers the method I have adopted for rotating a 

 thermo- combination by the influence of a central magnet, 

 the following description of the apparatus I have constructed 

 and employ for exhibiting the experiment, with an explana- 

 tion of its management, will, I humbly hope, be sufficiently 

 plain to be understood. 



N S, in the figure, 

 is the magnet; P c P 

 a piece of platinum 

 wire bent into the 

 form of a semicircle 

 or other convenient 

 curve; P s, Ps are 

 two pieces of silver 

 wire twisted to the 

 former at the extre- 

 mities P P. The 

 other ends of the 

 silver wires are bent 

 downwards at ss; 

 and made quite 

 sharp and smooth at 

 the points. These 

 points descend into 

 the metallic cell F E, 

 which contains pure 



quicksilver, with which the points communicate. A descend- 

 ing point c soldered to the platinum wire, forms the pivot on 

 which the moveable part of the machine turns. A small con- 

 cavity well polished at the bottom is made in the point of the 

 magnet, for the purpose of containing a small globule of mer- 

 cury, and likewise for the rotating pivot to work in. 



The point c being amalgamated, when it is placed in this 

 globule of mercurv, forms a communication with the magnet; 

 and the other part of the magnet which passes through the 

 cell communicates with the mercury in that cell : and the 

 points of the silver wires being immersed in this mercury, the 

 metallic circuit is thus rendered complete; first, through the 

 platinum wire from P to t\ thence through the pivot to 



lliC 



