Chemistry and Physics. 411 
fall, being surrounded by a helix of wire, whether any electric current 
was generated. Sometimes the cylinder was allowed to fall through the 
helix ; at other times with the helix ; and occasionaily the helix was 
slightest effect was visible. : 
| igni i therefore, two air-tight chambers were made, 
e ‘« males formed the chief part of the internal sur- 
sah se ed oy biti the flat ends of 
1th of an inch of each other, with a frame all 
vi Seve a 
euese equal he ols introdued into the chamber, and the rnd 
placed between the poles of the electro-magnet, any possible 
on of volume would be shown by the gauge as soon as the mag- 
a 
