OBSERVATIONS OF THE MAGNETIC FORCE. 
273 
tions observed with the weights at Toronto at different times between October 1842 
and December 1844 (Tables XIII., XIV. and XVI.), and the whole of the deflections 
observed with the same weights at different times at Norway House, viz. on July 13, 
1843; August 7, 8, 9, 1843 ; and September 7 , 1844 (Tables XV. and XVI.). From 
this comparison w r e obtain the force at Norway House = T0171 to 1 at Toronto; 
and we may consider the mean of these two determinations, or TO 184, as the result 
with F. A. 
Needle F. C. — By combining the angles of deflection observed with this needle at 
Norway House, with weights from V5 to 3'5 grains, on the 11th of August 1842 
after the new axle had been applied to it, and repeated on the 7th of September 
1844 with very small variation in the results, — with the angles observed with the 
same weights and the same axle at Toronto on the 14th and 17th of December 1844, — 
we obtain the Force at Norway House = T0184 to 1 at Toronto; which is precisely 
the same result as that deduced by needle F. A. The observations will be found in 
Table XVII. 
We may therefore regard TO 184 as the ratio of the Force at Norway House to 
unity at Toronto by Mr. Fox’s method. 
2. By Dr. Lloyd’s Method and Needles. 
L. A. — In consequence of the accident which befel this needle on the 20th of June 
1843, on the route between Toronto and Norway House, the connection of the series 
was broken, and we can derive no aid from it for the present purpose. 
L. B. — With this needle we have the deflections in natural temperatures at Toronto, 
in January and February 1843, in Table X., and with the same weight at Norway 
House on the 12th of July in the same year, in Table XXII. From this comparison 
we obtain the force at Norway House = T0232 to 1 at Toronto. When Lieut. Lefroy 
visited Norway House in August of the same year, the observations with this weight 
do not appear to have been repeated ; it had been considered expedient to change 
the weight employed in deflecting the needle at York Factory, and as the angles 
both with the old and new weights were observed at that station, and as nearly 
under the same circumstances as possible, we are furnished with the means of com- 
COS V 
puting the equivalent value of g - n ^ ^ for either weight at any other station, where 
one of the weights only may have been employed. If then we compute this value for 
the old weight, from the angles with the new one which were observed at Norway 
House on the 7th, 8th and 11th of August 1843 (Table XXIII. ), we obtain a second 
comparison with the original angles of deflection at Toronto, which gives the force 
at Norway House =T0185. The indirect process by which this last determination is 
obtained is to a certain degree a diminution of its value. On the other hand, it 
represents observations repeated on three different days at Norway House, whereas 
the first determination is from the observations of a single day only. Not feeling 
confident that either determination is entitled to a decided preference over the other. 
