ABSTRACTS FOR THE VERTICAL FORCE. 147 
TABLE XVII.—The Means of the Balance Magnetometer Readings, for periods of Three Months, for the 
Summer and Winter Months, and for the year 1842. 
Periods. 204, 23h, 2h, 5h, Mean. 
Ea EE | 
F y 1841. Mic. Diy. Mic. Div. Mie. Diy. Mic. Div. Mie. Div. Mic. Div. 
3 July, Aug., Sept. 776-9 787-5 797-5 822-3 45-4 
a October, November 654.2 678-2 699-5 715-5 61-3 
4 1842. 
it Jan., Feb., March 958-1 971-7 964-9 980-6 968-8 22-5 
April, May, June 906-0 905-8 907-5 925-5 911-2 19-7 
July, Aug., Sept. 850-0 849-5 856-9 888-7 861-3 39-2 
Oct., Nov., Dec. 797-9 811-7 817-4 826-1 813-3 28-2 
Jan., Feb., March, ) 
Oct., Nov., Dec. i 878-0 891-7 891-1 903-3 891-0 25-3 
April, May, June, 
July, Aug., Sept. \ 878-0 877-6 882-2 907-1 886-2 29-1 
The Year. 878-0 884-7 886-7 905-2 888-6 27-2 
In the periods of 1841, the force increases from 20" till 5®. 
The first quarter of 1842 shews a minimum to occur about 20", and before 2" ; in the second quarter, the 
minimum seems about 23°; the third, between 20" and 23; and in the last quarter, about 20". The highest 
mean is always at 55, The means for the winter months exhibit a minimum about 2"; the means for the summer 
months have a minimum between 20 and 23%, 
The means for the year exhibit an increase of force from 20 till 54, the increase from 23% till 2" being very 
small, 
The mean of the four observations for each quarterly period shews a very regular diminution of vertical force. 
The ranges are still irregular. 
The following Table has been formed by rejecting disturbances, according to the rule given after Table I. 
| TABLE XVIII.—The Monthly Mean Readings of the Balance Magnetometer, for the Hours 20, 23, 2, and 5, 
as Corrected in Table XVIL., and rejecting disturbances. 
Mean of the || Range of the Four Hours 
5h, Four Hours 
for each For each For each 
Month. Month. two Months. 
Mic. Div. a Mic. Diy. Mic. Div. Mie. Diy. 
July 817-1 860-6 43-5 
August 809-5 817-6 18-5 
September 745-4 765-4 34:0 
October 691-9 706-9 23-8 
November 657-3 675-1 20-7 
