358 
MR. C. CHREE ON THE EFFECTS OF PRESSE’RE 
Table VIIL 
-h. 
i 
0.. , 1 
First 
Cyclic 
“ on” — “ off.” 
Shock-effect of first “ of! ” 
A ' H- 3 i '. 
Oil . 
. 
“off.” 
A' 
•98 
2 - 0.5 
2-09 
- 1-17 
- -57 
■43 
1-61 
3-52 
2-19 
2-27 
■65 
■35 
1-96 
4-26 
2-17 
2-64 
■62 
•41 
2-65 
4-84 
1-83 
3-01 
■62 
■39 
. 3-8 
6-2 
1-64 
3-5 
•57 
■43 
61 
101 
1-66 
5-6 
•55 
■45 
8-7 
13-9 
1-59 
6-3 
11-5 
20-2 
1-76 
8-8 
+ -58 
■41 
■47 
17-3 
31-4 
1-82 
121 
■69 
■36 
-.52 
22-9 
37-6 
1-64 
11-3 
■54 
■29 
■62 
36-0 
49-4 
1-38 
11-4 
■35 
■23 
•68 
46-7 
53-3 
114 
12-5 
■36 
"23 
■69 
57-5 
58-1 
1-01 
10-6 
•09 
■18 
■69 
79-1 
61'3 
■76 
12-4 
■20 
■20 
■73 
93'6 
63-6 
■68 
111 
641 
•58 
124 
65-3 
■53 
1.34 
65-3 
•49 
^ 11-6 
■17 
•18 
•75 
147 
65'6 
■45 
180 
66-2 
•37 
213 
66-9 
■32 
224 
66-8 
■30 
299 
348 
67-4 
67-9 
■23 
■19 
^ 11-9 
■20 
•18 
•77 
400 
67'8 
■17 
1 
Fourth Series of Experiments. 
§ 35. In the last series of experiments, which extended into March, the effects of 
pressure on the induced magnetism were more particularly under investigation. 
Except on one or two occasions, the magnetometer was distant 50 cms. from the 
centre of the magnetising coil, and 81 cms. from the scale. Previous to each experi¬ 
ment the rod was demagnetised by reversed currents followed by vigorous tapping. 
After the introduction of the rod into the coil, fourteen pressure cycles were in 
general applied, readings being taken of the effects of the first four and the last four 
cycles. From these the effect of the first pressure and the cyclic effect are calculated. 
Then, leaving the current untouched, the rod was usually removed to a distance and 
replaced, scale-readings being taken. The comparison of the reading taken when 
the rod was out with that taken prior to its original introduction into the coil, tested 
the constancy of the magnetometer zero. From the readings taken before and 
after the rod s removal, we find the magnetisation 3 ^ of the rod at the end of the 
pressure cycles ; while from the readings taken before and after the rod’s re-introduc¬ 
tion we find the magnetisation ^3 on the second introduction of the rod into the coil. 
Thus, Ss ~ 3i is, as in former experiments, the increase in the magnetisation during 
the application of the pressure cycles, while is the magnetisation lost during 
the removal of the rod from the coil and its re-introduction. 
* In tlio entries above this point, in absence of experimental data, the cyclic “ on" — “ of" is neglected, 
Thns the results above this point are not strictly comparable with those below, 
