112 
COLONEL SABINE ON PERIODICAL LAWS DISCOVERABLE 
and in May, June, July, and August at Hobarton than in the other eight months of 
the year. As we have before seen that in the hours of their occurrence the disturb- 
ances appear to be governed by a law depending on local hours, so here, we recognise 
local effects depending on the period of the year, and possibly the influence of local 
seasons (since we are scarcely yet in a condition to discriminate as to causes). The 
mean monthly ratios in the different seasons are shown in the following Table, in 
which it will be remembered that November, December, January and February, are 
the winter months at Toronto, and May, June, July and August, at Hobarton. 
Table XII. 
Stations. 
Winter. 
Summer. 
Spring and Autumn. 
Numbers. 
Values. 
Numbers. 
Values. 
Numbers. 
ValueSi 
Toronto 
0*70 
0-72 
1-08 
0”96 
1-22 
1-31 
Hobarton ... 
0-56 
0*56 
1-28 
1*21 
M6 
1-24 
It is seen that the mean ratios, both of frequency and of aggregate value, are 
much less in the winter months at both stations than in the months of summer -or of 
spring and autumn, or, otherwise stated, least at Toronto in the months when the 
sun is in the southern signs, and least at Hobarton in the months when he is in the 
northern signs. 
If we compare the ratios of the numbers in the different months with those of the 
aggregate values in the same months, we perceive that the average value of a 
disturbed observation is greater at both stations in the winter than in the summer 
months, and that it is greatest in the intermediate or equinoctial months. In these 
respects, and also in the circumstance of the minimum ratio, both of numbers and 
aggregate values, being in the midwinter month, (January at Toronto, and June at 
Hobarton,) the two stations agree. They differ 1° in the relative amount of the 
mean ratios in the months of summer and in those of spring and autumn, the mean 
ratios being decidedly greater at Toronto in spring and autumn than in summer, 
whilst at Hobarton there is no such marked difference : and 2° in the character of 
the progression which the ratios at the two stations indicate in the different months : 
at Toronto there are two decided minima, one in the midwinter, and the other in 
the midsummer, with a progressive increase on either side of the respective minima 
to April and September, which are the months of maximum disturbance : at Ho- 
barton there is but one decided minimum, which is in the midwinter month ; whilst 
in January, which is the month of midsummer, there is as decided a maximum in 
the ratios, both of numbers and values. At the same time there is so far an agree- 
ment with Toronto, that there is a tendency at Hobarton towards secondary maxima 
in April and September. 
The points of accordance and points of difference thus noticed, are precisely the 
