repetition of M. Aragos's experiments on magnetismy ^c, 481 
city, at first entire, and then successively cut with a chisel in 
radii nearly up to the centre, as here represented. 
Fig. 2. Fig. 3. Fig. 4. Fig. 5. 
The times observed and forces deduced in the several cases 
were as follows : 
Rev. 
Disc uncut. 
Disc cut as in 
Fig.i. 
Disc cut as in 
Fig. 2. 
Disc cut as in 
Fig. 3 . 
Disc cut as in 
Fig. 4 . 
Disc cut as in 
Fig. 5 . 
t ~ 
/= 
t ” 
/= 
t “ 
/ = 
f — 
/ = 
i lama 
/= 
t "" 
/ = 
I 
28.2 
1258 
30*9 
1047 
33 " 
9*3 
42.1 
564 
48.1 
432 
55.6 
324 
2 
41 .2 
1178 
44-5 
47-4 
59.8 
69.0 
81.4 
302 
3 
50.6 
1 172 
55.0 
59.0 
74.7 
86.6 
* 03-3 
281 
4 
58.7 
1 161 
63*9 
68.3 
8S.O 
102. 1 
124.5 
258 
5 
66.4 
"34 
72.0 
77.2 
100. 0 
1 15.8 
145.9 
235 
Similar effects were observed in other metals, but in dif- 
ferent degrees. For instance, in the case of soft tinned iron, 
the same number of cuts, made in the same manner, pro- 
duced a very slight diminution of force, while in copper the 
effect of the same operation was to reduce the force in the 
ratio of 1 to 0.20. 
20. A thin disc of copper suspended at a given distance 
over the revolving magnet, performed 6 revolutions from 
rest in 54*. 8 . It was then cut in 8 places in the direction of 
radii nearly up to the centre and 45 ® asunder, by which ope- 
ration its magnetic virtue was so weakened, that it now 
required i2i».s to execute the same number of revolutions. 
The cuts were now soldered up with tin, and the magnetic 
action was now found to be so far restored as to enable it to 
