275 
OBSERVATIONS OF THE MAGNETIC FORCE. 
of the Force =1*867. We have also the observations with L. B. on the same day 
(May 29th) at Fort William, included in the same series with the observations of the 
12th of July at Norway House (Table XXII.) ; from these we have the Force at Fort 
William =1*864. The mean of the two determinations is 1*8655 ; which has there- 
fore been taken as the value whenever Fort William has been used as a base station. 
Tables XVIII. to XXIV. contain the several series with needles L. A. and L. B., 
arranged according to the base stations to which they respectively refer. The angles 
of deflection in these tables are always a mean of the angles in four different posi- 
tions of the needle and circle; i. e. with the face of the circle turned towards the 
east and towards the west, and with the needle reversed on its supports so that each 
end should rest alternately on the opposite plane. 
Since Lieut. Lefroy’s return to Canada from the Hudson’s Bay territories, Gam- 
bey’s circle has been supplied with a second pair of statical needles on Dr. Lloyd’s 
principle. These needles were used in 1845 by Lieut. Younghusband, R.A., at four 
stations in Canada, and by Lieut. Lefroy at six stations in Canada and the United 
States ; the observations are contained in Tables XXV. and XXVI. 
Table XII. — Observations on the Magnetic Force with Fox’s Needle F. A., made by 
Lieut. Lefroy in 1842 between Woolwich and Toronto. 
Station. 
1842. 
Angles of deflection with 
weights of 
Tempera- 
ture. 
Intensity. 
Remarks. 
2-0 grs. 
2-5 grs. 
3-0 grs. 
Woolwich .... 
July 7. 
27 30-0 
35 29*1 
44 00-9 
58-5 
1-372 
Base station. 
Quebec 
Sept. 1. 
20 20-1 
25 45-8 
31 34-5 
74 
1-829 
Royal Artillery Barracks. 
Three Rivers . . 
6. 
20 23-0 
25 40-8 
31 31-4 
66 
1-828 
Mr. Bell’s Garden. 
Sorel 
8. 
20 30-8 
25 57-6 
31 36-1 
61 
1-817 
Bank E. of the Roman Catholic Church. 
Kingsey 
10. 
20 35-8 
26 00-3 
31 47-8 
60 
1-810 
Captain Cox’s Garden. 
Stanstead .... 
12. 
20 38-6 
26 06-1 
32 06-1 
60 
1-801 
Garden of the Hotel near the Church. 
St. Helen’s .... 
16. 
20 32*5 
25 51-7 
31 48-3 
59 
1-813 
100 yards S.S.W. of the Barracks. 
New York .... 
26. 
21 01-6 
26 46-0 
32 39-2 
71 
1*771 
Lunatic Asylum, Manhattanville. 
Providence. . . . 
28. 
20 45*8 
26 39*1 
32 32-2 
75 
1-783 
Steam-boat landing. 
Cambridge .... 
Oct. 3. 
20 50-7 
26 34-5 
32 30*1 
63 
1*779 
Garden of the Observatory. 
Philadelphia . . 
6. 
20 3H 
26 19*7 
32 22*2 
62 
1*795 
Girard College. 
Baltimore .... 
8. 
20 51-6 
26 22-2 
32 26-5 
62 
1-784 
f Washington’s Monument N. 42° E., 
[ distant 400 yards. 
Washington . . 
10. 
20 54-8 
26 38-1 
32 41-1 
63 
1*774 
In the grounds west of the Capitol. 
Princeton .... 
14. 
20 53-0 
26 23-1 
32 18*0 
62 
1-785 
Field 200 yards east of the College. 
Newhaven .... 
18. 
21 00-5 
26 33-5 
32 39-4 
67 
1*775 
In an open space in Grove Street. 
West Point. . . . 
19. 
20 32-8 
26 03-6 
31 44-5 
54 
1-809 
Professor Bartlett’s Garden. 
Albany 
21. 
20 38*9 
26 12*0 
32 00-5 
55 
1*799 
Hill betweenOrange andPatroon Streets. 
Toronto 
26. 
20 12-3 
25 34-8 
31 19*7 
57 
1-838 
Magnetic Observatory. 
Note . — The Force at Toronto having been finally taken at 1'836 (p. 244 to 247), the values given in this Table for 
the stations in Canada and the United States require to be diminished by '002, and have accordingly been so dimi- 
nished in Table XXVII., in which the several determinations with the statical needles are collected in one view. 
