472 Mr, Babbage a?id Mr. Herschel's account of the 
the copper and other bodies in these experiments. It is ob- 
viously induced by the action of the magnetic bar, compass 
needle, &c. on their molecules. 
9. Our next enquiry was directed to the degree in which 
this developement of magnetic virtue takes place in different 
metals and other bodies. For this purpose two different 
processes were adopted. The first consisted in securing 
each of the 10-inch discs already spoken of successively 
on the vertical axis of our machine (which was now fitted up 
more firmly). Giving them thus a rotation in their own 
planes, the azimuth compass above mentioned was placed on 
a convenient stand centrally over each at the same distance. 
The deviations observed, and the ratios of their sines to that 
of the deviation produced by one of them ( copper ) chosen 
as a standard, were as follows, 
TABLE IV, 
Name of the revolving 
body. 
("Motion of the disc 
airect, or screwing.) 
(Motion retrograde, 
or unscrewing.) 
Mean. 
Ratio of the force 
to that of copper. 
Copper 
0 / 
II 30 
° , 
II 17 
0 / 
II 24 
1 .00 
Zinc 
10 7 
10 15 
10 II 
0.90 
Tin . - 
5 30 
S *2 
5 21 
0.47 
Lead 
2 50 
2 55 
2 53 
0,25 
Antimony 
I 12 
I 17 
I 16 
0. II 
Bismuth 
0 6 
0 6 
0 6 
0,01 
Wood r , 
0 0 
0 0 
0 0 
0.00 
The experiment was repeated (some weeks afterwards), 
placing the compass (by a more advantageous adjustment of 
the apparatus) much nearer the revolving disc, The results 
vvere as follows. 
