MAGNETIC DECLINATION AT TORONTO, ST. HELENA, AND HOBARTON. 553 
has inferred the existence of an inequality of the same kind, especially in the amounts 
of the similar deflections at opposite points of the hour-circle, in the Prague observa- 
tions. 
The disparity in the amounts of the deflections in opposite directions, viz. 17”'4 
easterly, and 10"'5 westerly, is one which, from its magnitude, cannot be imagined to 
be occasioned by accidental irregularities, and must be regarded as a real feature of 
the phenomena under discussion. 
M. Kreil has inferred from the Prague observations, that the variation due to the 
moon’s influence is not equally cognisable in all parts of the year, being greatest in 
summer, and disappearing wholly in the three winter months. To examine this 
question, I have caused in the following table the results of the Toronto observations 
to be arranged in two divisions, one comprising the results of thirty-six months com- 
posed of the six summer months in each of the six years under examination, and the 
other also of thirty-six months composed of the six winter months in each of the same 
years. 
Table II. 
Lunar hours. 
Summer. 
Winter, 
Table I. 
Lunar hours. 
Summer. 
Winter. 
Table I. 
Scale divisions. 
Scale divisions. 
Scale divisions. 
Scale divisions. 
Scale divisions. 
Scale divisions. 
0 
-0*51 
— 0-18 
— 0*35 
12 
— 0*43 
-0*42 
— 0*42 
1 
-0-54 
-0*10 
-0-32 
13 
— 0*40 
-0*21 
-0*30 
2 
-0-49 
+ 0-05 
-0*225 
14 
-0*32 
-0*08 
-0*19 
3 
— 0-35 
-fO-07 
-0*14 
15 
-0*37 
+ 0*12 
-0*12 
4 
— 0-08 
-|-0'36 
+ 0*14 
16 
-0*09 
+ 0*15 
+ 0*03 
5 
+ 0-07 
-1-0-29 
+ 0*175 
17 
— 0*01 
+ 0*31 
+ 0*17 
6 
+ 0-13 
-I-0-21 
+ 0*17 
18 
+ 0*27 
+ 0*34 
+ 0*31 
7 
-I-0-14 
+ 0-09 
+ 0*11 
19 
+ 0*15 
+ 0*07 
+ 0*11 
8 
-)-011 
-0-09 
+ 0*01 
20 
+ 0*07 
+ 0*04 
+ 0*06 
9 
-hO-01 
-0-25 
-0*12 
21 
-0*15 
-0*15 
-0*15 
10 
— 0-26 
— 0-33 
— 0*30 
22 
-0*45 
-0*24 
-0*35 
11 
— 0*42 
— 0-42 
-0*43 
23 
— 0*43 
-0*18 
-0*30 
The principal differences which show themselves in this comparison of opposite 
seasons are, that the easterly deflection at the upper culmination is less, and the 
westerly deflection on both sides of the meridian is greater, in the winter than in the 
summer half-period ; at the inferior culmination the amount of extreme easterly 
deflection is nearly identical in the two seasons. For the purpose of examining how 
far similar partial differences would be shown when periods of similar duration are 
taken without reference to season, I arranged as in the following table, a comparison 
of the results in two half-periods, each comprising three complete years (including 
both summer and winter months), and each, therefore, containing the same number of 
months, viz. thirty-six, as in Table II. 
4 c 2 
