372 
COLONEL SABINE ON PERIODICAL LAWS DISCOVERABLE 
Table V. 
Toronto Astrono- 
Mean diurnal variation occasioned by the larger disturbances. 
Toronto Civil 
inical Time. 
Declination. 
Inclination. 
Total Force. 
Time. 
h 
18 
6-29 W. 
-t-6'10 
Parts of the Total 
Force. 
-•000092 
6 A.M. 
19 
0-41 W. 
-1-0-18 
—•000092 
7 A.M. 
20 
0-52 W. 
-I-0-16 
—•000047 
8 A.M. 
21 
0-46 W. 
H-0-13 
—•000032 
9 A.M. 
22 
0-30 W. 
-I-O'IO 
—•000008 
10 A.M. 
23 
0-11 W. 
+ 0-09 
-1--000007 
11 A.M. 
0 
0-11 W. 
-I-0-09 
+ •000015 
Noon. 
1 
0-03 W. 
+ 0-09 
+ •000027 
1 P.M. 
2 
0-09 W. 
+ 0-05 
+ •000042 
2 P.M. 
3 
0*08 W. 
+ 0-07 
+ •000054 
3 P.M. 
4 
0-09 W. 
+ 0-05 
+ •000068 
4 P.M. 
5 
0-04 W. 
-J-0-08 
+ •000073 
5 P.M. 
6 
0-18 E. 
-1-0-14 
+ •000058 
6 P.M. 
7 
0-34 E, 
+ 0*14 
+ •000062 
7 P.M. 
8 
0-52 E. 
+ 0-16 
+ •000047 
8 P.M. 
9 
0-87 E. 
-f 0-16 
+ •000016 
9 P.M. 
10 
0-61 E. 
+ 0*15 
—•000022 
10 P.M. 
11 
0-53 E. 
+ 0-16 
-•000047 
11 P.M. 
12 
0-33 E. 
+ 0-14 
—•000098 
Midnight. 
13 
0-26 E. 
+ 0-18 
— •000125 
1 A.M. 
14 
0-17 E. 
-^0*19 
—•000132 
2 A.M. 
15 
0-16 E. 
-i-0-14 
—•000138 
3 A.M. 
16 
0*15 E. 
H-0-12 
—•000123 
4 A.M. 
17 
0-02 W. 
+ 0*10 
—•000109 
5 A.M. 
From this Table we find that the range of the diurnal variation of the different 
elements is as follows: viz. of the Declination 1'‘39, being from 0''52 W. at 8 a.m. 
to 0'’87 E. at 9 p.M. ; — of the Inclination 0''14, being from a minimum increase of 
0'*05 at 2 p.M. to a maximum increase of 0''19 at 2 p.m. ; — and of the Total Force 
•000211 parts of the total force at Toronto, being from a maximum decrease of 
•000138 at 3 a.m. to a maximum increase of ^000073 at 5 p.m. As the larger disturb- 
ances of each element, which have been separated by the processes and subjected to the 
analysis described in this communication, can by no means be supposed to include 
the whole of the disturbances of the class to which they belong, we can only regard 
the extent of the diurnal variation, as stated above, to be in each case a minimum 
limit, which would be certainly somewhat exceeded, if by any mode of proceeding 
we could succeed in separating the minor effects of the same causes ; but we have 
no reason to suppose that the epochs of maxima and minima, or the laws of inter- 
mediate progression, would sustain any material alteration thereby. And as the aggre- 
gate values of the disturbances are taken from the five years which include a com- 
plete quinquennial or semi-decennial period, the mean diurnal variation deduced 
from them must be considered as subject to a small quinquennial variation, ana- 
logous to that which has been found to exist in the ordinary solar diurnal variation. 
And as the sum of the variation values at the different hours taken with their proper 
