OF THE EARTH’S MAGNETISM. 549 
Makerstoun. Toronto, Trevandrum, Singapore, The Cape. Hobarten. 
Ranges, ae L266 11:06 12°12 9°02 12°60 9°89 
In either case the ranges for the stations Singapore and Hobarton are those 
which differ most from the others. 
102. If, in order to avoid points which may be supposed due to local disturb- 
ance, we take the mean of five days in the week having the highest mean, and 
in the two weeks (one preceding, one following) having the lowest means, the 
five days being those (corresponding to the Gottingen hour, 124) having simul- 
taneous observations at all the stations, we find— 
TABLE XXXII.—RancEs oF Five-Day MEans (1:00=0-00014 X). 
Hobarton. Singapore, Trevandrum. Cape. Makerstoun. Toronto. 
Five Days. 

ria ida EP Ge 
Mean. |Change.| Mean. |Change.| Mean. |Change.} Mean. |Change.| Mean. |Change.} Mean. |Change. 
-_ — 












— 


H. 
D. H. D. 
eb. 5 O— 9 23} 5:00 5°80 5:98 13°52 6°76 11:91 
‘ 4 1 : 
19 0O—23 13)11:13 10°98; 413-16 20°04 13-24 18-21 
Mar. 4 0O— 8 23] 4°63 5°70 6:14 13°63 6:04 11°75 
—— -——_ = | | | i 
Mean range, 6°31 5°23 7:10 6:46 6°84 6:38 







103. The excess at Trevandrum and the defect at Singapore may be acci- 
dental; but in any case we are entitled to conclude, that the amount of variations 
of the mean force in the period of 26 to 27 days, was equal (or nearly so) at all 
the stations when the effects of local disturbance are eliminated; and, that the 
directions of the variations were the same. 
104. I would only notice at present the curious repetition of movements shown 
in each of the six weeks projected in Plate X XVIII., indicating a period of from 
60 to 70 hours. It will require a more extended induction to determine the 
true length of this period, if it be constant, and to make any suggestion as to its 
cause. It does not seem improbable, however, that this cause, like the 26-27 
day period, may be connected with great physical movements in the envelope of 
our great heat-giver, the sun. 
