: 558 MR JOHN ALLAN BROUN ON THE HORIZONTAL FORCE 
By Singapore, April minus March = —1:32; we: minus April = — 0:04 
, Trevandrum, ... ie ae a 0-07, 
yy Nteblelena,, cee peer ae = —O079 
» Lhe mean, / ... bi, ee SS me bee © eee OO 
These quantities have been Med to obtain the value for March 1843 at the 
Cape; though it is evident that the value so obtained can be considered only 
approximative, owing to the very different change at St Helena. 
116. 1843, November 1.—Adjustment. As in this case only two days obser- 
vations were lost, the series has been connected by means of the corresponding 
cbservations at St Helena as follows :— 
By St Helena, November 2, 3, 5, minus October 27, 29, 30= + 2°58. 
This change from before to after the adjustment, being applied to the mean of 
the three days October 27, 29, 30 at the Cape, gives the value for November 2, 
3, 5 at the same place, upon the supposition that the series was unbroken. This 
value, compared with the mean for November 2, 3, 5 after the adjustment, gives 
a correction to be applied to all the following means. 
117. 1844, October 5.—Magnet changed, and readjustment. Not having the 
observations at St Helena for 1844, I have determined the connection of the 
series as follows :— 
Makerstoun, October 9, 10, 11, minus October 2, 3, 4, : = + 6:09 
Trevandrum, - = +850 
Singapore, se a Be : = +5°94 
Hobarton, ae dn eid : = +424 
Mean, ae nee are : = +619 
This mean has been applied as in the last case. 
118. Sr Hexena,* 1843, July 24.—In substituting a double rectangular 
case for the single cylindrical case previously in use, the instrument had received 
a shock which changed the scale reading. In order to determine the amount of 
change, the mean five days previously was compared with that five days subse- 
quently; the difference was found 19-6 scale divisions, which was assumed as the 
error due to the shock.; We find, however, by the observations at the Cape of 
Good Hope— 
Cape bifilar mean (July 26, 27, 28) minus (July 20, 21, 22) . : =— 574 
St Helena ae = + 37°88 
The correction of observations after the ‘shock to those before is faerie = — 43:62 
Or, in St Helena scale divisions, : : : : : : = — 23:08. 
This correction has been applied. 
119, 1844, February.—The magnet was removed for the determination of its 
temperature coefficient. The fortnightly means only for 1844 and 1845 are given 
in vol. i. of the St Helena Observations; the monthly means given in Table IX. 
* Lat. 15° 56’ 41" S., Long. 0h 22™ 42s W. Height above sea, 1760 feet. Observations, vol, Ve 
printed under the superintendence of Lieutenant-Colonel E. Sasrne. 
+ Adjustment, &c., St Helena, vol. i. p. 33. 

