312 
MAGNETIC SURVEY IN NORTH AMERICA. 
Table XLIII. (Continued). 
Station. 
Date. 
Horizontal 
component. 
Mean 
horizontal 
component. 
Total force 
in absolute 
measure. 
Remarks. 
Fort Alexander 
Rat Portage 
Portage des deux Rivieres 
Prairie Portage 
Portage du Chien 
Lake Superior 
Pie Fort 
White River 
Fort Michipicoton 
Gargantua 
Sault St. Mary 
La Cloche 
Penetanguishene 
Toronto | 
Toronto 
Toronto 
Toronto 
Woolwich 
1844. 
1844. 
1844. 
1844. 
1844. 
1844. 
1844. 
1844. 
1844. 
1844. 
1844. 
1844. 
1844. 
1842. 
1843. 
1845. 
1845. 
1846. 
1846. 
2-698 b. 
2-876 b. 
2-930 c. 
2-844 c. 
2- 836 c. 
3- 213 c. 
2-725 c. 
2-803 c. 
2- 870 c. 
3- 190 c. 
3-026 c. 
3-108 c. 
3-326 c. 
J 3-537 a. 
3-537 b. 
3-535 b. 
3-533 b. 
3-729 b. 
2*698 
2-876 
2-930 
2-844 
2- 836 
3- 213 
2-725 
2- 803 
2-870 
3- 190 
3-026 
3-108 
3-326 
V 3-535 
3-729 
14-08 
13-97 
13- 89 
14- 18 
14- 17 
15- 89 
13- 84 
14- 12 
13-93 
15- 26 
13-98 
13- 64 
14- 08 
13-90 
10-39 
Values of the Magnetic Force at Dr. Locke’s stations. 
Dr. Locke’s determinations were of the ratios of the horizontal component of the 
Force to its value at Cincinnati taken as a base station : it is therefore requisite to 
establish, in the first instance, the relative values of the magnetic Force at Cincinnati 
and Toronto on the best evidence that the observations furnish. For this comparison 
we have — 1°. Dr. Locke’s observations with Hansteen’s apparatus, at Toronto on the 
20th of June, and at Cincinnati on the 4th of July 1844, combined with observations 
of the Inclination on the same days. The observations of horizontal Force give the 
ratio ‘77 84 at Toronto to unity at Cincinnati, and those of Inclination 70° 25'*0 at 
Cincinnati, and / 5° 1 3'*4 at Toronto. Whence, if we take the total Force at Toronto 
in the arbitrary scale as 1*836, its value at Cincinnati is 1*795. 
2°. Dr. Locke’s determination of the ratios of the horizontal force at New York, 
Cambridge, and Philadelphia, to unity at Cincinnati, with the Inclination at each sta- 
tion, combined with Lieut. Lefroy’s determination of the ratios of the horizontal 
force at the same three stations to the force at Toronto, all which were observed 
with the magnets of the German transportable magnetometer. The place of obser- 
vation at New York, Cambridge and Philadelphia, was the same with both observers ; 
viz. the Lunatic Asylum at Manhattanville near New York, and the magnetic obser- 
vatories at Cambridge and Philadelphia. 
The particulars of this comparison are as follows : — 
