RESISTANCE BY A METHOD BASED ON THAT OF LORENZ. 
97 
(2) Observations on plugs. 
Microscope readings (corrected). 
Plug. 
Left. 
Plug. 
Right. 
Diff. (L - R). 
O 
O 
(L - R) - d 
(7) 
927-3 
(16) 
179-2 
748-1 
- 750 
- 1-9/a 
(8) 
155M 
(15) 
834-1 
717-0 
- 716 
+ 1-0 
(4) 
1052-0 
(11) 
1185-2 
- 133-2 
+ 107 
- 26-2 
(3) 
328-9 
(12) 
2447-9 
- 2119-0 
4-2094 
-25-0 
(10) 
1042-6 
(1) 
1232-3 
- 189-7 
4- 177 
-12-7 
(9) 
1167-6 
(2) 
1126-0 
41-6 
- 55-s 
- 13-9 
(13) 
294-3 
(6) 
1199-8 
- 905-5 
4- 887 
- 18-5 
(14) 
1409-9 
(5) 
757-5 
> 
652-4 
- 669 
-16-6 
Mean . 
. -14-2/a 
.•. Mean distance between the mean 
diametral planes of the coils 
= 30'60167 cm. - 14-2 /a- 
208-3 p = 30-57942 
cm. 
(3) Temperature of Marble Cylinders. 
No. 
Before resistance 
measurements. 
After resistance 
measurements. 
Difference, 
°C. 
°C. 
°C. 
1 
16-6 
18-8 
4-2-2 
2 
16-55 
18-75 
4-2-2 
3 
16-5 
18-8 
+ 2-3 
4 
16-55 
18-9 
4-2-35 
Mean 
. . . 16-5 S 
Mean . . 
. 4- 2" 2 5 
Effective temperature = 16° 
• 5 5 C. 4- 0 • 42 (2°-25 C.) = 17° 
•5 C. 
* The correction is equal to the difference of the distances of the plugs from the mean diametral planes 
of the coils, these distances being deduced from the metrology measurements. Thus we obtained from 
these measurements:—Distance (d x ) of plug 7 from centre = 9'3892 cm., distance (d 2 ) of plug 16 from 
centre = 9 •3142 cm. Hence, when the coils are parallel, the distance of plug 16 from plug 7 is greater 
than the distance between the mean diametral planes of the coils by 9'3892 — 9’3142 = 750/t and a 
corresponding correction must therefore be applied. For our purpose it is necessary to measure four 
distances between four pairs of plugs, but, in practice, we measured eight distances between eight pairs of 
plugs in order to obtain a check. The agreement was always good. 
VOL. CCXIV.—A. 
O 
