AND STRAIN ON THE ACTION OE PHYSICAL EORCES. 
55 
Experiment X. 
Carbon rod, length between E and D 45 centims., diameter ’434 centim. 
Number of 
kilogs. in the load. 
Number of divisions 
of the platino-iridium wire 
through which it was neces¬ 
sary to move the sliding 
piece in order to restore the 
balance. 
Average alteration of 
resistance per kilog. in terms 
of the division of the platino- 
iridium wire. 
2 
37-00 
18-50 
4 
74-75 
18-69 
6 
111-80 
18-63 
Mean 18"61 
In Table II. will be found some data respecting the alteration, of resistance produced 
by loading, the values of “ Young’s modulus/' specific resistance, specific gravity, and 
section of each rod. 
Table II. 
Number 
of 
carbon. 
Section 
in 
square 
centims. 
Specific 
gravity 
water 
at 
4° C = 1 
= A. 
Specific 
resistance 
at 15° C. 
“ Young’s 
modulus ” 
in grammes per 
square centim. 
= e. 
Increase 
of resistance 
due to a load of 
1 grm. per 
square centim. 
= x. 
Increase of 
resistance 
which would 
be caused 
by a load 
sufficient to 
double the 
length 
= e xx 
~V- 
Increase of 
specific 
resistance 
which would 
be caused 
by a load 
sufficient to 
double the 
length 
1 
•1411 
1518 
4591x10- 6 
233-8 x 10 G 
11420 x Hr 1 - 
2-470 
0-970 
2 
•1307 
1-550 
4182 x10- 6 
264-3 x 10 6 
8991 x 10~ 13 
2-377 
0-877 
3 
•1480 
1-552 
4483 x10-e 
270-0x10° 
9535 x 10- 1 - 
2-575 
1-075 
4 
1351 
1-579 
3937 xlO- 6 
329-0 x 10 c 
8610 x 10- 13 
2-835 
1-335 
5 
•1216 
1-581 
3774 x10 -6 
279-Ox 10° 
7684 x 10- 13 
2-144 
O’644 
Means 
1-556 
4193xl0- 6 
275-2 x 10 6 
9248 x 10~ 13 
2-480 
•980 
Remarks on Table II. 
The sections of the rods were much more uniform than would perhaps have been 
expected ; for example, in the case of No. 3, as measured by a gauge at five points 
equally apart, the diameter was found to be ‘434, ’434, ’434, ’434, and ‘433 centim., and 
the other rods were found to be nearly of the same uniformity as this one. 
The specific gravities were determined by breaking the rods into pieces about 
5 inches in length and binding a thin copper wire round them, which latter was 
