498 
Mr. Babbage on electrical 
in diameter, which was fixed by sealing-wax on a disc of 
box wood 2.5 inches in diameter : this latter was screwed 
upon a wooden axis. No electricity was communicated 
either to the needle or the glass disc, except that which 
resulted from cementing the latter by sealing-wax to the 
box wood on which it was fastened, and perhaps the coating 
of wax on the edges of the needle might have given it a very 
slight charge. The glass disc was now made to revolve at 
about 38 revolutions in a minute : there was a small motion 
of the needle in the same direction. 
Experiment 2. 
The same apparatus being employed, a large stick of com- 
mon sealing-wax was excited and applied two or three times 
to the needle, in order to charge it. As soon as it was quite 
at rest, the glass disc was made to revolve more slowly than 
before, when the needle began to deviate in the direction of 
rotation, and followed the glass. Some doubt being ex- 
pressed by a friend who was present as to the influence of 
the air set in motion by the apparatus, the electric charge of 
the needle was increased, and the velocity of rotation was 
diminished : the needle deviated as before, but much more 
rapidly. To remove some doubt as to the influence of any 
twist in the silk ; whilst the needle was revolving in one 
direction, the rotation of the glass disc was reversed ; after a 
short time the motion of the needle was destroyed, and it 
returned in the contrary direction. 
For the purpose of ascertaining still more satisfactorily the 
effect which might be ascribed to the influence of air, the 
following experiment was made. 
