534 MR JOHN ALLAN BROUN ON THE HORIZONTAL FORCE 
from November 1846 till February 1850, but with no observations in the months 
February to June 1849. The following are the changes from month to month of 
the absolute values :*— 
TABLE XVL—Montuiy CHANGES OF HORIZONTAL FORCE AT THE CAPE OF GOOD 
Hops, FROM OBSERVATIONS OF ABSOLUTE INTENSITY. 




MONTHS. 1846. 1847. 1848. 1849. 1850. Mean. 
December to January, . . . ae — 0002 | +-0009 | +-0029 | —:0137 | —-0025 
January ,, February,. . . oe — ‘0055 | —-0050 ph +°0012 | —-0031 
February © ;,, March,’ ©". *.)": as —'0009 | + -0026 53 as + 0008 
March 3, april, cies ats —°0027 | +:0004 Bee a —:0011 
April Bet NLA Aci gt tata _ +:0019 | +-0029 Bh a's +0024 
May » June, . +0038 | +:0015 es As +:0026 
June » duly, ae Pe —0007 | —:0051 a are —-0029 
July by) AADOUBE «ae ef f.. — 0008 | +-0038 | —:0021 aR +0003 
August ,, September, . . eis — ‘0054 | —-0008 | —:0033 wee — 0032 
September ,, October, . . . Pee — 0038 | —:0062 | —-0027 on — ‘0042 
October ,, November, . . wes —'0016 | —:0049 | —-0008 ae — ‘0024 
November ,, December, . . | +:0007 | —:0009 | +:0020 | +:0012 Bas +0008 

54. If we assume the value for January to be 0:0107, we shall obtain the 
values for the other months as in the second column of the following table; by 
repeating the month of January we find the secular change for one year to be 
—(0-0124; correcting the quantities in the second column at the rate of +0-00103 
per mensem, and subtracting the resulting value for February from all, we 
obtain the quantities in the third column. 
TABLE XVII—MonTHLY VARIATIONS OF HORIZONTAL FORCE, DEDUCED FROM 


TABLE XVI. 
MonrTuHs. Mean. meray eh 
January, . : 4 ‘ ; 0107 "0020 
February, . 3 5 : : “0076 “0000 
March, . ; : ; ‘ "0084 -0018 
April, 5 ; 3 : . 0073 0017 
May, : : : ; : ‘0097 0052 
June, - : : : ‘ 0123 “0088 
July, é " : : 4 0094 “0069 
August, . : : ; : 0097 0083 
September, : ; - : "0065 °0061 
October, . ; ; 5 ‘ 0023 “0029 
November, : 5 : : “0000 -0017 
December, : ! : ; “0008 "0035 

* See Cape of Good Hope Magnetical Observations, vol. i. Table xxxvi. p. xx. 

