PROFESSOR KEELY’S MAGNETICAL OBSERVATIONS. 
205 
the greatest difference between any partial result by A(l) and the mean dip was 01'7, 
while for A(2) it was 03'‘2 ; the difference for A(l) indeed was, in two-thirds of the 
results, less than l'. Though this might not affect the means of a great number of 
observations, it is evident that if the observer is limited to one observation with each 
of these needles, he is far more likely, setting aside the effects of carelessness, to ob- 
tain a truly comparable value of 6 by needle A(l) alone, than by a mean of the two. 
I have therefore confined my observations for 6, on my tour, with one exception, to 
A(l). The direction of the meridian has always been obtained with A(l), by con- 
sidering the meridian as 90° from a mean of the positions of the vertical limb of 
the circle, when the needle resting on its supports had an inclination of 90° with its 
marked face alternately north and south. Moreover, in all my observations with 
the dipping or force needles, whenever the instrument was newly placed, the ad- 
justments for correct position of the microscopes, the axis, the level, and the planes 
of support, were duly made if necessary. Table II. gives the details of the observa- 
tions made in the provinces for v and Q with the logs of <p, by each needle reduced to 
50° Fakr. 
Table II. 
No. for 
reference. 
Place. 
Date. 
1847. 
Latitude 
to 
nearest 
minute. 
Longi- 
tude to 
For inclination. 
Observations with Lloyd 
needles. 
Logarithms of (p. 
nearest 
minute. 
Needle. 
Poles 
direct. 
Poles 
reversed. 
6- 
Needle. 
Temp. 
Fahe. 
V . 
44 39 
296 23 
75 37 
75° 37'-l 
75 37 
39 32-1 1 
Means used. 
1. 
HaUfax, N.S 
Aug. 20. 
A(l) 
L(l) 
77-3 
1-9310218 
Halifax, N.S 
21. 
A(l) 
75 37-6 
75 38-3 
75 37-9 
L(l) 
77-5 
39 32-5] 
Halifax, N.S 
21. 
L(2) 
76-9 
32 151 
2. 
Hiltz’s, N.S 
23. 
44 57 
295 9 
A(l) 
75 37 
75 37 
75 37 
L(l) 
740 
39 36-5 
1-9307381 
3. 
Windsor, N.S 
24. 
45 10 
295 44 
A(l) 
75 40-6 
75 42-2 
75 41-4 
L(l) 
76-8 
39 38 
1-9309837 
4. 
Kentwlle, N.S 
25. 
45 12 
295 14 
A(l) 
75 45 1 
75 46-3 
75 45-7 
L(l) 
521 
39 09-6 
1-9320107 
5. 
Bridgetown, N.S. ... 
26. 
44 51 
294 22 
A(l) 
75 40-9 
75 41-9 
75 41-4 
L(l) 
75-3 
39 05-2 
1-9323155 
6. 
Annapolis, N.S 
27. 
44 45 
294 04 
A(l) 
75 41-7 
75 41-2 
75 41-5 
L(l) 
68-5 
38 58-8 
1-9325703 
Annapolis, N.S 
27. 
L(2) 
703 
31 41-2 
1-9508199 
7. 
St. John, N.B 
Sept. 1. 
45 14 
293 57 
A(l) 
75 55-7 
75 55-7 
75 55-7 
L(l) 
59-9 
38 22-2 
1-9348103 
8. 
2. 
A(l) 
76 59-2 
76 58-5 
76 58-9 
Lri) 
72-0 
39 19-7 
9. 
Woodstock, N.B. ... 
4. 
46 09 
292 25 
A(l) 
/77 12 
77 10-2 
77 IM 
L(l) 
73-2 
39 14-8 
1-93739671 
Woodstock, N.B. 
1 
76 59-6 
11. 
L(2) 
63-2 
30 56 1 
10. 
Riviere des Chutes ... 
6. 
46 36 
292 16 
A(l) 
77 IM 
77 11'7 
77 11-4 
L(l) 
69-0 
38 54-3 
1-9381584 
11. 
Lf2) 
45-3 
30 37-8 
11. 
Grand Falls of St. J ohn 
7. 
47 03 
292 15 
A(l) 
77 28-1 
77 31 
77 29-5 
L(l) 
70-7 
39 29-1 
1-9379492 
10. 
77 27-5 
77 31-6 
77 29-5 
1(2) 
59-0 
31 09 
19^; 
12. 
Grand River 
8. 
47 11 
292 03 
A(l) 
77 36-4 
77 34-8 
77 35-6 
L(l) 
49-2 
38 51-4 
1-9392578 
Grand River 
8. 
1(2) 
61-4 
31 01-6 
13. 
Madawaska 
9. 
47 22 
291 41 
A(l) 
77 44-9 
77 44'8 
77 44-8 
L(l) 
65-1 
39 09-3 
1-9395932 
Madawaska 
9. 
A(l) 
L(2) 
77-6 
31 08-7 
1-9573159 
Madawaska 
9. 
A(2) 
77 49-3 
77 42 
77 45-6 
2 E 2 
