RESISTANCE BY A METHOD BASED ON THAT OF LORENZ. 
59 
measurements made in a large number of planes. This difference can be obtained 
from curves showing the cross-section of the cylinders, and in all cases we have 
estimated this difference and applied a correction. 
It will be observed that the means of the 1913 measurements are about 2/jl less 
than those of 1912. This difference cannot be due to the gauge bars employed, and 
we believe it is not due to errors of observation; it is probably due to a real 
Table V. — Giving the Results of the Individual Measurements on the same Coils, 
when Measurements were made in Three Planes only. 
Axial plane No. . . 
Between 3 and 4 
Between 7 and 8 
Between 11 and 12 
Measurements on 
strand No. 
v -v- - ' 
Diameter = 35'8750 cm. + 
Mean. 
fl. 
ix. 
+ 
2 
24 
28 
31 
27- r 
12 
24 
29 
32 
28's 
24 
26 
32 
35 
31 'o 
36 
32 
35 
38 
35'o 
48 
40 
42 
47 
43'o 
60 
42 
45 
47 
44 ' 7 
72 
54 
66 
65 
61* r 
84 
61 
66 
67 
64'r 
96 
58 
61 
69 
62-7 
108 
67 
71 
74 
70-7 
120 
57 
69 
63 
63'o 
132 
61 
67 
67 
65'o 
144 
56 
75 
70 
67'o 
156 
71 
79 
76 
75-3 
168 
67 
80 
74 
73*7 
180 
68 
75 
71 
71-3 
192 
70 
79 
75 
74-7 
Mean . . . = 
51 e 
58-5 
58' 9 
56's 
j 
.•. Mean diameter = 35’8750+ 56' 3 fx = 35 '88063 cm. at 20 ° "0 C. 
From fig. 12 and the observations in Table IY. we conclude that the mean diameter in these three 
planes is less than that of the complete coils by 0'5/x. Hence mean diameter of the coils = 35'8806s cm. 
at 20 °-0 C. 
diminution in the diameters of the coils due to a displacement of small crystals of 
marble under the wires. This is quite possible, as the coils are wound under tension 
and have been subjected to considerable changes in temperature (due to the current 
passing through them) since 1912. 
Tables IY. and Y. give the results of the individual measurements made in April, 
1913, of the coils on cylinder No. 1. 
