ME. W. CROOKES ON REPULSION RESULTING FROM RADIATION. 
531 
Table II. 
Tension of enclosed 
air, in millims. of 
mercury. 
Temp. = 16° C. 
Bar. =772 millims. 
Amplitude of half 
oscillation, in millims., 
at end of 40'' obser- 
vation. 
772-0 
+ 0-460 
770-0 
+ 0-540 
769-5 
+ 0-570 
769-0 
+ 0-440 
769-0 
+ 0-520 
769-0 
+ 0-440 
769-0 
+ 0-450 | 
565-0 
+ 0-560 
557-0 
+ 0-540 
472-0 
+ 0-490 j 
440-0 
+ 0-550 
369-0 
+ 0-416 
213-0 
+ 0-233 
207-0 
+ 0-130 
189-0 
+ 0-180 
173-0 
+ 0*140 
164-0 
+ 0-100 
162-0 
-0-100 
142-0 
-0-120 
132-0 
— 0-130 
127-0 
-0-090 
105-0 
-0-140 
102-0 
+ 0-083 
73-0 
-0-130 
60-0 
— 0-123 
56-0 
-0-136 
51-0 
-0-030 
41-0 
+ 0-150 
33-5 
+ 0-170 
32-0 
+ 0-106 
23-0 
+ 0-110 
22-0 
+ 0-080 
16-1 
+ 0-170 
16-0 
+ 0-140 
7-1 
+ 0-380 
6-0 
+ 0-293 
3-9 
+ 0-610 
1-9 
+ 0-880 
1-2 
+ 0-755 
0-9 
+ 0-340 
0-7 
-0-740 
0-6 
-1-700 
0-3 
-3-800 
0-2 
-5-080 
0-0 
-5-680 
-0-05 
-6-320 
the neutral point, or the point where attraction changes to repulsion, is in this series 
lower than in the former. There it occurred at a tension of about 0'3 millim. of mer- 
cury ; here at about 0 - 8. Neither does the previous attraction attain such strength, 
although the ultimate repulsion is more intense. The agreement is, however, suffi- 
ciently satisfactory, considering the faulty method of measurement. 
There are many errors almost inseparable from this form of apparatus. The making 
4 a 2 
