Bee roe rena rts eo 
Pipe 5; J hia 
W. Thompson on the size of Atoms. 39 
matical mind. The idea which it conveys to the mathematical 
mind is, in my opinion, irredeemably false. For ave no 
faith whatever in attractions and fhe ies acting se a sae ey 
sibly similar. But contiguous cubes of one ten-millionth of a 
centimeter must be very sensibly different. So in a solid mass 
Saeuts lengths of 20,000 continaten 
each, may contain, one of them nine hundre d and ninety-nine 
bricks and two half bricks, and the other one éhoosand bricks: 
thus two contiguous cubes ‘of 20,000 centimeters breadth may 
be considered as sensibly | similar. But tw o adjacent lengths of 
forty centimeters each might contain, one a them one brick 
and two half bricks, and the other two whole bricks ; and con- 
tiguous cubes of forty centimeters would be very sensibly dis- 
similar. In short, optical dynamics leaves no alternative but 
to admit that the diameter of a mo lecule, or the distance 
ys sc ae on the shee Seay of oe made 
“ial or ten years ago, and described in a letter to Dr. Joule, 
nected with the two plates of a galvanic element, having about 
three-quarters of the electro-motive force of a Daniel's ag a 
Measurements published in the Proceedings of the Royal 
Society for 1860 showed ve the sietion tween parallel 
plates of one metal held at a distance apart small in com- 
parison with their ane and ears connected with such 
a galvanic element, would experience an attraction amount- - 
ing to two ten-thougand-millionths of a gram weight per 
area of the opposed surfaces equal to the square of the 
a centimeter ihe, be p with a corner of each touching a 
-) se thousandth of a centimeter eee 
Let the plates kept thus in metallic communication with o 
another be at first wide apart, except at the corners ‘einalie 
the little globe, and let them then be gradually turned roun a 
