1056 
DR. T. R. ROBINSON ON THE DETERMINATION OP 
winter is 1'665 ; and tlie times so deduced are certain to less than 0 s 'l. Latterly the 
time was noted by a watch. 
(58.) It was soon found that the method proposed in paragraph (52) is not avail¬ 
able, for the wind is never uniform long enough to make two successive experiments 
fairly comparable. It was therefore necessary to use that of paragraph (53). Assum¬ 
ing such values of a, x, and y, the constants of equation III. as will give V very nearly 
equal to V' (the accented letters belong to E), we may correct them so that the mean 
V — Y may vanish. This assumes first, that however the wind may vary in the course 
of an observation from one instrument to another, yet if the time be sufficient it comes 
to each of them with an equal amount; its deficiency at one part of the time being 
made up by its excess at another; and secondly, that the V computed for a mean 
value of v will be its own mean value. 
(59.) As to the first of these assumptions, I have come to the conclusion that if an 
observation lasts for nine or ten minutes, the average action of the wind on the two 
instruments will be nearly equal, though during portions of the time it may vary very 
much. This may be illustrated by the following table, which contains a set of v and v 
taken with the normal frictions at K and E, which are 13' 5 and 23'2 ; these were 
taken September 17, 1878, under unfavourable circumstances, for the wind was S.W. 
The v and v ought to be nearly equal, for the difference of the friction will only 
diminish v by 0'24. 
Table XX. 
No . 
Time . 
V. 
v'. 
v — v'. 
No . 
Time . 
V. 
v\ 
v — v'. 
No . 
Time . 
V. 
v'. 
v-v'- 
1 
s . 
15*1 
6-522 
4-660 
1-868 
22 
s . 
5*2 
6-441 
6-441 
o-ooo 
43 
s . 
18-4 
5-349 
6-876 
- 1-527 
2 
28-0 
5-254 
5-254 
o-ooo 
23 
10-3 
5-475 
5-475 
o-ooo 
44 
29-4 
7-175 
8-400 
- 1-225 
3 
25-5 
7-156 
6-620 
0-536 
24 
9-2 
6-132 
4-599 
1-533 
45 
50-3 
7-540 
6-143 
1-397 
4 
11-5 
6-084 
3-650 
2-334 
25 
17-5 
8-012 
6-409 
1-603 
46 
32-4 
6-077 
5-208 
0-869 
6 
11-3 
7-638 
6-236 
1-402 
26 
22-0 
5-702 
4-474 
1-228 
47 
9-2 
4-589 
5-842 
- 1-253 
6 
21-1 
5-313 
5-313 
o-ooo 
27 
9-6 
5-882 
5-882 
o-ooo 
48 
16-4 
5-989 
5-135 
0-854 
7 
13-5 
4-174 
2-086 
2-088 
28 
32-4 
7-791 
7-353 
0-438 
49 
11-8 
7-142 
5-959 
1-183 
8 
8-5 
6-624 
6-624 
o-ooo 
29 
10-8 
6-482 
6-482 
o-ooo 
50 
19-3 
5 082 
4-841 
0-241 
9 
12-1 
4-642 
3-481 
1-161 
30 
12-1 
4-595 
5-795 
- 1-200 
51 
45-3 
6-512 
6-512 
o-ooo 
10 
28-7 
2-934 
4-995 
0-939 
31 
15-2 
3-697 
4-622 
- 0-925 
52 
39-2 
5-378 
3-222 
2-148 
11 
10-9 
6-458 
5-162 
1-296 
32 
35-4 
4-637 
3-174 
1-462 1 
53 
14-0 
3-193 
3017 
0-176 
12 
13-2 
4-256 
5-311 
- 1-055 
33 
10-8 
5-163 
2-581 
2-582 ' 
54 
13-9 
5-040 
4-032 
1-008 
13 
5-8 
7-314 
7-314 
0-000 
34 
22-5 
3-739 
1-246 
2-493 
55 
20-4 
4-116 
3-430 
0-686 
14 
10-6 
9-247 
9-247 
o-ooo 
35 
14-6 
3-852 
0-764 
3-088 
56 
19-7 
4-281 
2140 
2-141 
15 
25-1 
8-959 
6-298 
2-661 
36 
29-4 
4-298 
1-910 
2388 
57 
15-5 
4-525 
1-802 
2-723 
16 
7-3 
3-817 
1-915 
1-902 
37 
8-4 
5-032 
3-355 
1-677 
58 
14-8 
3-794 
2-846 
0-948 
17 
11-2 
5-006 
3-754 
1-252 
38 
15-0 
4-693 
2-816 
1-877 
59 
31'9 
5-599 
4-900 
0-699 
18 
13-7 
6-127 
6-127 
o-ooo 
39 
13-3 
4-229 
4-229 
o-ooo 
60 
24-5 
4-560 
3-434 
1-126 
19 
12-4 
6-815 
4-544 
2-271 
40 
18-2 
3-885 
3-885 
o-ooo 
61 
18-0 
4-691 
5-473 
- 0-782 
20 
6-5 
8-589 
8-589 
o-ooo 
41 
45-5 
7-247 
8-153 
- 0-806 
62 
21-2 
6-626 
8-540 
- 1-914 
21 
17-1 
6-554 
5-735 
0-819 
42 
11-5 
7-358 
6-512 
0-846 
Total time =646 3 '7 ; mean 'r=5'816 ; mean +=5*218 ; mean v— +=0'598. 
These show plainly both the variation of wind at one anemometer and the difference 
at the two. In No. 14, i>=9'247 ; in No. 10, it is 2'934. These represent V=26*264, 
and 8*551. If we look to the column v—v, at No. 35 we find +3*088, at No, 62 
