MAGNETIC VARIATION AT TORONTO. 
503 
derived from the two half-periods, viz. 1844 to 1846, and 1846 to 1848; the year 
ending June 30, 1846 having single weight, and the years ending June 30, 1844 and 
184.5 in the one case, and the years ending June 30, 1847 and 1848 in the other case, 
having double weight in the respective combinations. 
Declination . — To complete the view of the Moon’s diurnal influence on the mag- 
netic elements at Toronto, a recalculation has been made of the lunar-diurnal varia- 
tion of the declination, using the more perfect normals derived by the exclusion of all 
disturbances equaling or exceeding five minutes of arc*. Table IV. contains the 
horary variation of the declination at the different hours of the lunar day in each of 
the six years, from July 1, 1842 to June 30, 1848, and in the eighth column the mean 
variation in the six years. 
Table IV. 
One scale-division ==0'‘72!. 
Lunar 
hours. 
In the year ending June 30. 
Mean of the 
six years. 
Lunar 
hours. 
1843. 
1844. 
1845. 
1846. 
1847. 
1848. 
1. 
2. 
3. 
4. 
5. 
6. 
7. 
8. 
9- 
sc. div. 
sc. div. 
sc. div. 
sc. div. 
sc. div. 
sc. div. 
sc. div. 
0 
— 0-20 
-0*42 
— 0*45 
-0*40 
— 0*46 
-0*37 
-0*38 
0 
I 
-0‘11 
-0*31 
-0*18 
-0*37 
-0*64 
-0*29 
— 0*32 
1 
2 
-0-08 
-0*28 
+ 0*04 
-0*28 
-0*39 
— 0*31 
-0*22 
2 
3 
-0*09 
— 0*08 
-0*07 
0*00 
— 0*36 
— 0*13 
-0-12 
3 
4 
4-0*26 
+ 0*09 
+ 0*31 
+ 0*08 
+ 0*13 
+ 0*28 
+ 0*19 
4 
5 
-1-0-39 
+ 0*09 
+ 0*42 
4-0*52 
+ 0*20 
+ 0*45 
+ 0*35 
5 
6 
-h0*66 
+ 0*40 
+ 0*23 
+ 0*77 
+ 0*15 
+ 0*48 
+ 0*45 
6 
7 
-1-0-51 
+ 0*29 
+ 0*47 
+ 0*56 
+ 0*31 
+ 0*29 
+ 0*40 
7 
8 
+ 0*17 
+ 0*26 
4-0*08 
+ 0*50 
+ 0*09 
+ 0*10 
+ 0*20 
8 
9 
— 0*14 
+ 0*21 
— 0*31 
+ 0*31 
— 0*23 
+ 0*35 
+ 0*03 
9 
10 
-0*36 
— 0*24 
— 0*57 
— 0*22 
-0*40 
-p0*04 
-0*29 
10 
11 
-0*51 
— 0*33 
-0*66 
-0*54 
-0*24 
-0*49 
-0*46 
11 
12 
-0*59 
-0*48 
-0*51 
-0*51 
-0*52 
-0*22 
-0*47 
12 
13 
-0*37 
— 0*27 
— 0*45 
— 0*34 
-0*29 
— 0*44 
-0*36 
13 
14 
-0*17 
-0*31 
— 0*24 
-0*32 
+ 0*07 
— 0*15 
-0*19 
14 
15 
-1-0-07 
— 0*14 
+ 0*04 
-0*12 
+ 0*52 
-0*10 
+ 0*04 
15 
16 
-i-0*12 
+ 0*22 
+ 0*31 
+ 0*14 
+ 0*43 
4-0*20 
+ 0*24 
16 
17 
+ 0*37 
+ 0*45 
+ 0*51 
+ 0*16 
+ 0*55 
+ 0*49 
+ 0*42 
17 
18 
4- 0*43 
+ 0*74 
-p0*65 
+ 0*39 
+ 0*47 
+ 0*58 
+ 0*54 
18 
19 
-f0*26 
+ 0*25 
+ 0*52 
+ 0*21 
+ 0*55 
+ 0*39 
+ 0*36 
19 
. 20 
-h0*29 
+ 0*15 
4-0*35 
+ 0*20 
+ 0*22 
4-0*05 
+ 0*21 
20 
21 
4-0*08 
+ 0*15 
+ 0*10 
— 0*15 
-0*21 
-0*30 
-0*06 
21 
22 
-0*26 
— 0*05 
— 0*04 
-0*23 
— 0*42 
- 0*42 
— 0*24 
22 
23 
-0*29 
-0*37 
-0*33 
— 0*25 
-0*31 
-0*34 
-0*32 
23 
i 
If we represent the mean of the six years (column 8) by the usual formula of sines 
and cosines, we have the coefficients of the several terms of the complete foruiula as 
follows ; the coefficients are expressed in seconds of arc, and a is counted in hours 
(multiplied by 15°) from the time of the Moon’s upper culmination : — 
* Philosophical Transactions, 1856, Art. XIX. 
