86 Mr. Christie on the mutual action of 
when the parts were retained, and when they were removed 
and glass substituted, were so small, that I shall only give the 
results where they were retained, excepting in the case of the 
largest circle. In all cases tissue paper was placed between 
the pieces to prevent contact. 
I5g.l. Fig. 2. Fig. 3. Fig .4. 
The magnets revolving with their axes at the distance 3*2 inches from the axis of rotation. 
Disc cut as Fig. 4, 
Disc uncut. 
Disc cut 
as Fig.l. 
Disc cut 
as Fig. 2 . 
Disc cut as Fig. 3 . 
Disc cut as Fig. 4 . 
the interior rings and 
small disc removed. 
0 
Time. 
a. 
Time. 
cc 
Time. 
x 
Time. 
X 
Time. 
CC 
Time. 
X 
<L> OJ 
- 0 jz 
sec. 
sec. 
sec. 
sec. 
sec. 
sec. 
> 0 
1 
360 
58-0 
1607-6 
6o-o 
1506-1 
63-0 
1372-3 
68*5 
1170-2 
7 9 -o 
896-3 
78-5 
907-1 
x. , 0 
2 
720 
85-5 
1 549-5 
88-o 
1468-6 
92-5 
1342-8 
100-5 
1158-8 
1 1 6*5 
898-6 
116-5 
898-6 
3 
1080 
107-0 
1558-0 
I I 1*0 
1462*7 
1 16-0 
1357-6 
126*5 
1176-8 
I 53-5 
875.8 
153-0 
879-2 
® w O 
4 
I 44 ° 
128*0 
1542-2 
* 34*5 
1423-4 
140-5 
1330-6 
154-0 
1163-5 
I 94-5 
868-7 
194-0 
871-0 
.2 *3 3 
5 
1800 
150-0 
I 5 I 7*7 
1 5 7'3 
1410-7 
164*5 
1326-7 
184-5 
1150-4 
to 2 « . 
£ u O 0 
6 
2160 
172*0 
1502-5 
*« 3-5 
1389-2 
192-5 
1 3 *7*3 
223-0 
II 5 S 7 
7 
2520 
200-5 
* 474*4 
220-0 
1361-4 
234-0 
1308-7 
J 
18 
2880 
252*5 
*4 5°"5 
Values of t r and 
=J0. 
267-0 
1448-0 
267*5 
1352-0 
265*5 
1308-0 
265-0 
1 1 16-8 
266-0 
855-5 
268-5 
864-15 
Mean values of as 
15167 
1421-8 
i 333 -o 
1156-0 
879-0 
884-0 
As might be expected, the effects produced by the circular 
separation are not great when the line of separation is near 
to the centre ; but as it approaches the circumference under 
