HEAT OF EVAPORATION OF WATER. 339 
“ This we termed the “ bridge correction.” 
“ The resulting values are expressed in legal ohms, and true ohms = reading in legal 
ohms (1 — °0024275).” 
The above extract is sufficient to explain the operations. I now give a complete 
example of a determination of R, and the subsequent calculations. 
The value of @, we obtained by direct observation of thermometer I]., and d’ by 
observation of the bridge reading. Then 0, = @+d’. 
TABLE XX VI.—Determination of Coil Resistance. October 11. 










| Correction || 
| 4 Galvanometer | Observed | Tempera- us for tem- || Plug R+7r 
cor ENE. swings.* : ture coils. aE perature correction. (box ohms). 
| coils. 
|. 331 170 
N, 191 341 58140 aio 58°450 +:002 +007 08459 
1460 171 
417 296 
N, 222 350 1095225 | 17°08 1095°783 +:033 +°777 1096°583 
(art OSmemo4: 
407 281 
N, 201 322 1095228 Se 1095°834: +:033 +:777 1096°634 
| 206 41 
| 282 128 
N, | 173 329 58108 ie 58°352 +002 +007 58361 
109° 201 | | 





As previously remarked, the difference in the resistance of the leads accounts for 
the difference between N, and N,, and N, and N,. 
We thus get 
RR, +7r= {(N,+ N,) —(N, + N,)}/2 = 1038199 box ohms. 
10°37648 “ legal” ohms. 
10°35128 true ohms. 
I 
Reading of thermometer No. Il. = 684°77 millims. = 29°:997 C. 
3 bridge-wire == 590°1, and null-point = 599'25 (see p. 288). 
Therefore 
d= — 0842 ¢ 
* Resistance in battery circuit (2 Leclanchés) = 700 ohms when observing N, and Ny, and 2900 chms 
wheu observing N, and N,. 
Dy Ok Ws 
