331 
diurnal variation of the magnetic needle, &c. 
Colonel Beaufoy states, “ from several observations it is 
after eleven at night/' 
The observations at Fort Enterprise were made every day 
from the 10th January to the 16th March, and from the 22d 
March to the 7th April ; but as considerable disturbance took 
place in the direction of the needle, in taking the mean of the 
deviations at the several hours of observation, it is necessary 
to exclude those days on which observations were not made 
at each of these hours. The following table contains the 
mean, so taken, of the variations at different hours in the 
months of January, February, and March. 
r o h A. M. 
i h P. M. 
5 h P. M. 
9 h P. M. 
I2 h P.M. 
No. of Day’s 
Observations. 
January - - - 
35° 54' E 
35°42'E 
35 0 42 ' E 
35° 44' E 
35° 5 1 ' E 
18 
February - - - 
35 54 
35 47l 
35 40 
35 4*i 
35 4if 
19 
Means for Jan. i 
and Feb. ji 
35 54 
35 45 
35 4 1 
35 43 
35 4 6 
March - - - 
9 A. M. 
35 57 
35 39 
35 3° 
35 3° 
35 33 
J 3 
Means for Jan. ? 
Feb. and March J 
35 43 
35 37 
35 385 
35 42 
Lieut. Hood states, that the maximum variation east oc- 
curred at 9 A. M. and the minimum at 3 or 4 P. M. ; but 
these means clearly indicate that the minimum happened 
after 5 P. M. Some latitude however must certainly be al- 
lowed in determining these points. 
Canton's observations in 1759, which are published in the 
51st vol. of the Philosophical Transactions, appear to have been 
made with great care, with the view of determining the amount 
of the variation at different seasons of the year. On a few days 
