204 
PROFESSOR KEELY’S MAGNETICAL OBSERVATIONS. 
Table I. 
Observations for the Temperature Coefficient of L(2). Waterville Mean Time. 
Low temperatures. 
High temperatures. | 
1347. 
t. 
V, 
6- 
‘P- 
1847- 
t>. 
v'. 
6'. 
P'. 
d h 
Feb. 10 
261 
26 26 33i 
7i 55 57i 
0-9166800 
d h 
Feb. 10 
72-1 
26 59 46^- 
75 55 57# 
0-9142133 
18 20-4 
11-4 
26 16 33| 
76 02 14 
0-9177840 
20 00-5 
70-0 
27 11 41 
75 56 45# 
0-9133754 
19 20 3 
14-8 
26 18 13| 
75 56 45f 
0-9173431 
21 23-7 
64-5 
27 15 33i 
75 56 17# 
0-9130579 
21 20-5 
17-6 
26 39 35 
75 56 17f 
0-9157335 
22 23-7 
60-5 
27 09 20| 
76 00 58# 
0-9138112 
22 20-5 
15-6 
26 24 20| 
76 00 58^ 
0-9171375 
23 23-7 
84-2 
27 50 06i 
75 55 26# 
0-9104202 
23 207 
34- 1 
26 59 42 J 
75 55 26f 
0-9141865 
26 00-3 
80-6 
27 38 39§ 
75 56 16# 
0-9113319 
25 21-3 
33-5 
26 52 51i 
75 56 161 
0-9147465 
27 00 
73-3 
27 38 46| 
75 57 38# 
0-9114102 
26 21-3 
25-6 
26 59 49| 
75 57 38| 
0-9143125 
28 23-7 
69-7 
27 27 59# 
76 00 01# 
0-9123667 
28 20-5 
35-4 
27 00 Oli 
76 00 04 
0-9144437 
Mar. 1 23-5 
67-7 
27 26 27i 
75 57 30# 
0-9123212 
Mar. 1 20-5 
310 
26 56 56 
75 57 30| 
0-9145187 
Feb. 18 23-5 
62-3 
27 04 124 
76 02 14 
0-9142698 
Means 
24’51 
26 41 27| 
75 57 54^ 
0-9156886 
Means 
70-49 
27 22 15# 
75 57 54# 
0-9126578 
Calculated value from means of t, 
V, and 6 
. 0-9156908 
Calculated value from means of t', 
v', and 6' 
.0-9126596 
Observations for the Temperature Coefficient of L(1 ). 
Waterville Mean Time. 
Feb. 7 20-5 
29-9 
35 55 26|- 
75 54 214 
0-8723502 
Feb, 8 03 
75-1 
36 11 41# 
75 54 21# 
0-8710132 
8 20 
31-9 
36 00 08i 
75 57 55 
0-8723284 
9 02 
86-9 
36 23 47# 
75 57 55 
0-8703828 
9 20 
34-2 
35 59 36^ 
75 56 05-4 
0-8721856 
10 01 
78-3 
36 15 45# 
75 56 05# 
0-8708558 
10 20 
32-6 
35 52 53i 
75 58 514 
0-8730186 
10 23 
78-8 
36 16 50 
75 58 51# 
0-8710536 
11 20-5 
240 
35 51 37 i 
76 00 064 
0-8732486 
12 01 
74-8 
36 15 36# 
76 00 06# 
0-8712842 
12 20 
25'9 
35 53 28^ 
75 58 32^ 
0-8729382 
13 00 
74-3 
36 13 11# 
75 58 32| 
0-8713204 
14 20-5 
16 7 
35 44 27i 
75 58 3U 
0-8736786 
14 23 
63-0 
36 13 38# 
75 58 34# 
0-8712866 
15 20-5 
7-0 
35 44 33f 
75 58 24f 
08736534 
15 23 
71-0 
36 18 04# 
75 58 24# 
0-8709048 
16 21 
19-0 
35 54 58f 
75 58 044 
0-8727674 
16 23-5 
75-7 
36 24 26# 
75 58 04# 
0-8703460 
18 207 
150 
35 57 57,V 
76 02 14 
0-8729488 
19 00-7 
67-8 
36 29 45# 
76 02 14 
0-8703426 
19 207 
20-4 
35 55 44 
75 56 45| 
0-8725744 
20 01 
81-0 
36 28 25 
75 56 45# 
0-8698804 
Means 
23-33 
35 53 424 
75 58 104 
0-8728811 
Means 
75-15 
36 19 12 
75 58 10# 
0-8707882 
Calculated value of ip from means of t, v, and ^ 
...-8728810 
Calculated value of P' from means of t', v', and f . 
..0-8707881 
whence by the formula we have for L(l) the coefficient *0000463 ; and for 
L(2) the coefficient *0000722. 
The values of d in the above observations were obtained by the two dipping-needles 
accompanying the Lloyd needles, and which I shall call A(l) and A(2). The obser- 
vations were made in the usual way with poles direct and reversed, in each case the 
marked limb of the circle facing both east and west ; each single reading being a 
mean of from four to eight, successively obtained by lifting the needle from its agate 
supports-by the lifting frame. The mean of the whole is, for A(l), twenty complete 
observations, 7^° 57' 03"; for A(2), nineteen complete observations, 75° 58' 50"; whence 
the mean dip for Waterville (lat. 44° 33' N., long. 293° 23'), Feb. 17, 1847, is 75° 57' 56|". 
Between June 14th and June 30th I made at the same place, with each of the 
needles, six complete observations, on as many days, and when, from the less varia- 
tions of temperature, the adjustments were more under control ; the results were 
for A(l), 75° 56' 27" ; for A(2), 75° 59' 31" ; mean dip for June 22nd, 75° 57' 59". In 
all my observations with these dipping-needles, up to the time of my excursion, I had 
observed far greater irregularities in A(2) than in A(l) ; in this last set, for instance. 
