IN THE ME^N EFFECTS OF THE LARGER MAGNETIC DISTURBANCES. 137 
being greater in amount from 6 p.m. to 10 p.m. than the westerly deflection at Hobarton 
at the same hours. 
The absolute quantities shown in this Table are small, but it must be remembered 
that they represent the mean daily effect of the disturbances, during the whole 
period of three years under discussion ; while the disturbances themselves are by no 
means of daily occurrence. Small as the numbers are, however, they make a very 
important change in the character of the residual diurnal variation, both at Toronto 
and Hobarton, from that which is derived from the mean of all the observations 
including the disturbed ones. In order that this may be distinctly seen, I have 
placed in the following Table (XII.) the mean diurnal variation as it would be 
shown at each hour with and without the disturbances, and have added columns con- 
taining the amount of the change in the mean direction in the intervals from hour 
to hour ; the extreme westerly position at Toronto and the extreme easterly position 
at Hobarton are taken as the respective zeros, from which the diurnal variation at the 
several hours is counted. The sign -|- in the column of differences signifies, there- 
fore, that the north end of the magnet has moved during the interval to the east at 
Toronto and to the west at Hobarton, and the sign — has the contrary signification. 
Table XII. — Diurnal variation at Toronto and Hobarton, with the disturbed obser- 
vations retained, and with the same omitted ; derived from hourly observations 
during the years 1843, 1844 and 1845. 
Toronto. 
Hobarton. 
Toronto 
mean time. 
Retaining the 
disturbed observations. 
Omitting the 
disturbed observations. 
Hobarton 
mean time. 
Retaining the 
disturbed observations. 
Omitting the 
disturbed observations. 
Hours. 
Diurnal 
variation. 
Ditferences.l 
Diurnal 
variation. 
Oifferences. 
Hours. 
Diurnal 
variation. 
Differences. 
Diurnal 
variation. 
Differences. 
6 A.M. ... 
7 a . m . ... 
8 A.M. ... 
9 A.M. ... 
10 A.M. ... 
11 A.M. ... 
Noon 
1 P.M. ... 
2 P.M. ... 
3 P.M. ... 
4 P.M. ... 
5 P.M. ... 
6 P.M. ... 
7 P-M. ... 
8 P.M. ... 
9 P.M. ... 
10 P.M. ... 
11 P.M. ... 
Midnight... 
1 A.M. ... 
2 A.M. ... 
3 A.M. ... 
4 A.M. ... 
5 A.M. ... 
7- 52 
8- 43 
8-67 
7*74 
5-49 
2-86 
0-78 
0-00 
0- 30 
1- 37 
2- 69 
3- 89 
4*72 
5-20 
5- 57 
6*07 
6- 15 
5-86 
5-66 
5-54 
5-40 
5- 57 
6- 03 
6-58 
+ 6*91 
+ 0-24 
-0-93 
— 2-25 
— 2-63 
— 2*08 
-0-78 
+ 0-30 
+ 1-07 
+ 1*32 
+ 1-20 
+ 0-83 
+ 0-48 
+ 0*37 
+ 0-50 
+ 0-08 
-0-29 
-0-20 
-0-12 
— 0-14 
+ 0*17 
+ 0*46 
+ 0-35 
7- 52 
8- 43 
8*76 
7-81 
5-33 
2- 83 
0- 83 
0-00 
0*32 
1- 43 
2- 70 
3- 81 
4- 34 
4- 90 
3-00 
3-26 
5- 37 
5-42 
3-23 
3-18 
5-18 
3*41 
5- 98 
6- 36 
+ 6-91 
+ 0-33 
-0-93 
— 2-28 
-2-70 
-1-98 
— 0-83 
+ 0-32 
+ M1 
+ 1*27 
+ M1 
+ 0-73 
+ 0-36 
+ 0-24 
+ 0-26 
+ 0-11 
+ 0-03 
-0*17 
—0-07 
0-00 
+ 0*23 
+ 0-37 
+ 0*58 
6 A.M. ... 
7 A.M. ... 
8 A.M. ... 
9 a.m. ... 
10 A.M. ... 
11 A.M. ... 
Noon 
1 P.M. ... 
2 P.M. ... 
3 P.M. ... 
4 P.M. ... 
5 P.M. ... 
6 P.M. ... 
7 P.M. ... 
8 P.M. ... 
9 P-M. ... 
10 P.M. ... 
11 P.M. ... 
Midnight... 
1 A.M. ... 
2 A.M. ... 
3 A.M. ... 
4 A.M. ... 
5 A.M. ... 
5- 29 
6- 03 
7*03 
7*55 
6-94 
5*17 
2*87 
0-81 
0*11 
0-00 
0-90 
2*15 
3*10 
3- 80 
4*49 
5-05 
5-40 
5-57 
5-52 
5*23 
4- 92 
4*61 
4-55 
4-78 
+ 0-76 
+ 0-98 
+ 0*52 
— 0-61 
-1*77 
—2-30 
— 2*06 
— 0-70 
— 0-11 
+ 0*90 
+ 1-25 
+ 0*95 
+ 0-70 
+ 0-69 
+ 0*56 
+ 0*35 
+ 0-17 
-0-03 
-0*29 
-0*31 
— 0-31 
— 0-06 
+ 0-23 
5'-26 
6-06 
6*99 
7*53 
6-91 
5*14 
2*83 
0*79 
0*10 
0*00 
0*89 
2*10 
3- 00 
3*38 
4- 16 
4*39 
4- 91 
5- 10 
5*07 
4*83 
4-61 
4-42 
4+7 
4-76 
+ 6-80 
+ C-93 
+ 0*54 
-0*62 
-1*77 
— 2*31 
2-04 
-0*69 
— 0-10 
+ 0-89 
+ 1*21 
+ 0*90 
+ 0-38 
+ 0-58 
+ 0-43 
+ 0-32 
+ 0-19 
-0-03 
-0-24 
— 0-22 
-0*19 
+ 0-05 
+ 0*29 
MDCCCLI. T 
