282 MECHANICAL ELECTRICITY. 



chanical processes — drilling, turning, filing, &c. — 

 and which, on its discovery, I named ^^ Mechanical 

 Electricity." 



In the printed report of the British Association 

 for 1845, which met at Cambridge, 1 find that 

 M. Paul Erman, of Berlin, presented a paper, 

 containing one or two experiments of a somewhat 

 similar nature to the Association, but of which 

 I was not aware until the publication of the report, 

 and the completion of many of my experiments. 



April 2, 1 846, 1 made the following experiment : 



Upon a mandril of copper, a cylinder of Bis- 

 muth was cast. One end of the mandril was 

 fixed in dry wood, and arranged in a turning 

 lathe. The other revolved against the point of 

 the "following up head stock," as is usual. The 

 surface of the cylinder or disc was turned smooth, 

 the mandril having been previously soldered to 

 the Bismuth, so as to insure full metallic commu- 

 nication. 



Instead of a metal rest, a wood one was now 

 used, and afterwards a small piece of wood placed 

 under the ordinary rest ; to insulate this, and the 



