166 
CAPTAIN YOUNGHUSBAND ON PERIODICAL LAWS 
The limit beyond which an observation should be regarded as disturbed, was, of 
coarse, arbitrarily fixed ; and as the principle on which the disturbances were sepa- 
rated was the same as that which formed a guide in tlie previous investigation, it is 
only necessary here to repeat, that the absolute numbers which express the frequency 
and amount of the disturbances cannot be compared at any two stations, but a 
comparison may with propriety, and has been made, between the ratios of each year, 
01- season or hour, to the respective mean quantities. . . t 
In a paper by Colonel Sabine already alluded to, a comparison has been instituted 
of the disturbances at Toronto and Hobarton, stations almost as far from each other, 
geographically, as it is possible for two places to be situated on the surface of the 
earth, but possessing considerable analogy in their magnetical lelations. The ie,.u t 
of the comparison was to show a striking connection between the two places m the 
laws of the occurrence of disturbances, whether as regards the hour of the day, the 
season of the year, or the year itself. Now St. Helena and the Cape of Good Hope, 
situated near together, are unlike magnetically, as well as in geographical position, 
to either Toronto or Hobarton; and I am desirous, in addition to presenting an 
investigation into the periodical character of the laws of disturbance operating at 
the new stations, to point out in what respect the character agrees, and m what it 
differs, from that which has been found at Toronto and Hobarton. 
We' may expect, from facts already known, some agreement^ in the amount of 
disturbance in the same years at different places. Table I. exhibits the ratios of the 
numbers and aggregate values of the disturbed observations in the different years to 
the average annual number and aggregate value, also the average value of one 
disturbance in each year. 
Table I. 
Years. 
St. Helena. 
Cape of Good Hope 
Numbers. 1 
Aggregate values. 
Average value of 
one disturbance. 
Numbers. 
Aggregate values. 
Average value of 
one disturbance. 
1841 
1842 
1843 
1844 
1845 
1846 
1847 
0-98t 
0-82 
0- 9011 
1- 00 
1-06 
l-25t 
0-96t 
0-76 
0-9011 
0- 97 
1- 03 
1-37 «il 
1 
/ 
2-43 1 
2-31 
2-47 11 
2-41 
2-42 
2-73 1 
0- 97* 
1- 25 
0-57t 
0-90 
0- 93 
1- 38§ 
1-07* 
1-26 
0-53J 
0-88 
0- 91 
1- 36 § 
3-10* 
2-86 
2-62 1 
2-76 
2-76 
2-78 § 
1 
I 
The observations are here too incomplete, and their duration too limited to derive 
more than a general indication of the action of the same law, which has been shown 
to exist at Toronto and Hobarton, of the periodical character of the number and 
magnitude of the disturbances during a cycle of years ; both at Toronto and Hobarton 
^ From six months’ observations, f From four months’ observations, f From ten months’ observations. 
11 From ten months’ observations. § From six months’ observations. From eight months’ observations. 
