IN THE MEAN EFFECTS OF THE LARGER MAGNETIC DISTURBANCES. 135 
Table IX. 
Montlis. 
Easterly. 
Westerly. 
Excess of 
Westerly. 
Months. 
Easterly. 
Westerly. 
Excess of 
Westerly. 
January 
80 
128 
48 
J'jiy 
22 
34 
12 
February 
73 
88 
15 
August 
47 
55 
8 
March 
70 
89 
19 
September ... 
50 
75 
25 
April 
69 
79 
10 
October 
58 
80 
22 
May 
16 
32 
16 
November ... 
42 
81 
39 
June 
5 
14 
9 
December ... 
81 
111 
30 
In this comparison of the laws which appear to regulate the distribution of the 
larger disturbances in the several months of the year at Toronto and Hobarton, I 
have been desirous of giving quite as much prominency to the points of difference at 
the two stations as to those of resemblance ; believing the one to be quite as likely 
to conduct to a recognition of the physical causes of these remarkable phenomena as 
the other. But it must be remembered that three years scarcely form a sufficient 
basis of observation for secure and correct deduction of the minor details of an 
annual variation, though they may be sufficient in the case of diurnal variation. A 
continuation of the comparison by a similar examination of the hourly observations 
at Toronto and Hobarton in the three following years, 1846, 1847 and 1848, may be 
expected to elucidate what may appear obscure or uncertain on the present occasion, 
and will enable the differences as well as the analogies of the annual laws at the two 
stations to be discussed on more secure grounds. I will therefore proceed to the 
distribution of the 1479 disturbed observations at Hobarton into their respective 
hours of occurrence, for the purpose of examining the evidence they may afford of a 
diurnal law, for the deduction of which in its main features at least three years’ 
continuance of observation ought to be a sufficient time. 
Table X. shows the number of disturbed observations occurring at each hour of 
the twenty-four, separating them also into easterly and westerly disturbances. 
Table X. 
Hours of 
Hobarton time. 
Easterly 
disturbances. 
Westerly 
disturbances. 
Total. 
Hours of 
Hobarton time. 
Easterly 
disturbances. 
Westerly 
disturbances. 
Total. 
6 A.M 
27 
21 
48 
6 P.M 
22 
20 
42 
7 a.m 
38 
25 
63 
7 P.M 
11 
33 
44 
8 A.M 
32 
36 
68 
8 P.M 
10 
50 
60 
9 A.M 
34 
24 
58 
9 P.M 
9 
68 
77 
10 A.M 
36 
18 
54 
10 P.M 
5 
66 
71 
11 A.M 
37 
28 
65 
11 P.M 
7 
70 
77 
Noon 
40 
33 
73 
Midnight ... 
17 
66 
83 
1 P.M 
41 
31 
72 
1 A.M 
17 
67 
84 
2 P.M 
36 
22 
58 
2 A.M 
16 
44 
60 
3 P.M 
36 
22 
58 
3 A.M 
29 
40 
69 
4 P.M 
37 
17 
54 
4 A.M 
28 
27 
55 
5 P.M 
25 
21 
46 
5 A.M 
23 
17 
40 
• If we regard, first, the westerly disturbances, we perceive a scarcely less striking 
disparity in their relative numbers during the hours of the day and of the night than 
was found to be the case with the easterly disturbances at Toronto. From the early 
