378 
PRESTON. 
No. of 
circle. 
Radius. 
Mean height 
of ring. 
Nap. log. 
factor. 
No. of 
Compart¬ 
ments. 
F 
Jed. 
1 
o 
Miles. 
1.02 
1.12 
1.23 
1.35 
1.49 
1.64 
1.80 
1.98 
2.18 
2.40 
2.64 
2.90 
3.19 
3.51 
3.86 
4.25 
4.67 
5.14 
5.65 
6.21 
6.83 
7.51 
8.26 
9.09 
10.00 
11.00 
12.10 
13.31 
14.64 
16.10 
17.71 
19.48 
21.43 
23.57 
25.93 
Miles. 
0.075 
0.09255 
19 
0.0132 
Q 
0.095 
.09360 
19 
.0169 
O 
0.115 
.09298 
19 
.0203 
X 
0.143 
.09880 
19 
.0268 
6 
7 
0.161 
.09534 
19 
.0292 
0.176 
.09285 
19 
.0310 
8 
9 
10 
11 
12 
13 . 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 
31 
32 
33 
34 
35 
0.191 
.09481 
19 
.0344 
0.210 
.09574 
19 
.0382 
0.227 
.09591 
19 
.0414 
0.244 
.09459 
19 
.0438 
0.272 
.09352 
19 
.0483 
0.310 
.09489 
19 
.0559 
0.382 
.09498 
19 
.0690 
0.421 
.09447 
19 
.0756 
0.513 
.09550 
19 
.0931 
0.595 
.09349 
19 
.1056 
0.705 
.09489 
19 
.1271 
0.814 
.09361 
19 
.1448 
0.927 
.09335 
19 
.1644 
0.972 
.09418 
19 
.1739 
1.035 
.09393 
19 
.1847 
1.120 
.09427 
19 
.2006 
1.103 
.09496 
19 
.1990 
1.071 
.09480 
19 
.1929 
0.975- 
.09492 
19 
.1758 
0.864 
.09504 
18 
.1478 
0.684 
.09520 
18 
.1172 
0.484 
.09518 
17 
.0783 
0.325 
.09502 
11 
.0340 
0.211 
.09531 
9^ 
.0191 
0.129 
.09523 
8J 
.0104 
0.079 
.09540 
8 
.0060 
0.039 
.09518 
6 
.0022 
0.011 
.09543 
5 
.0005 
The first column has the number of the circle; the second 
gives the length of the corresponding radius. Following 
this is the mean height of the ring between the successive 
radii. The fourth column contains the factor given by the 
expression 
Nap. log 
+ i/r 2 2 4- h 2 \ 
\?i + l/Vf 2 + h 2 ) 
The next column gives the number of compartments in 
