Suspension of the Magnetic Needle. 85 
glass; and at so great a distance, appeared to me at first to be the 
effects of atmospheres of heat, acting in a similar manner to 
those of electricity ; and on shewing them to a believer in ani- 
mal magnetism, he was confident that the light substances 
were moved by the magnetic atmosphere of the body, and that 
there was a difference betwixt the attraction of the right hand 
and the left : but the doubts of my philosophical friends in- 
duced me to try the following experiment, which fully ex- 
plains the matter. 
EXPERIMENT VII. 
A piece of paper was tied over the mouth of a glass jar about 
four inches in diameter. Two holes were made in the paper 
opposite to each other, and near the edge of the glass. The 
jar was placed upon a table, and suffered to stand a considerable 
time to cool in a room without fire ; I then sat near it, on the 
side where one of the holes in the paper was in the nearer, and 
the other in the farther end of the diameter. I next filled an- 
other glass with smoke, and placed it with its mouth over the 
two holes in the paper. The smoke was now seen to descend 
through the farthest hole, and mixing with the air in the lower 
jar, plainly shewed, that the air moved slowly towards the side 
of the glass warmed by the heat of my body. 
EXPERIMENT VIII. 
The last experiment proved, that the current of air moving 
towards, and then ascending up the heated side of the glass, 
might turn the broader end of the light suspended body, like 
the vane of a weathercock : but that it might still more de- 
cisively appear to be occasioned by a current of heated air, I 
