OF THE EARTH’S MAGNETIC FORCE AT BOMBAY. 
79 
On and after September 21, 1871, the place of observation was changed from the 
basement of the Electrometer Tower to the top room of the same building, the former 
height above the ground having been 6 feet and the present height being 38 feet. 
9. Annual Mean Values of the Lip and Annual Increase of Lip for seven years . — 
Table VII. 
Year. 
Mean Dip. 
Annual Increase of Dip. 
1867-68 
19 2-3 
+1-9 
1868-69 
19 4-2 
1869-70 
19 61 
+ 19 
1870-71 
19 76 
+ 1-5 
1871-72 
19 9-5 
+ 1-9 
1872-73 
19 14-8 
-j-5'3 
1873-74 
19 14-5 
— 03 
Mean Dip for seven years. 
19 8-4 
f Corresponding to epoch 
t October 1, 1870. 
II. Leclination. 
10. Monthly Mean Values. — In Table VIII. are collected the monthly means of the 
values of absolute declination, as observed from July 1867 to December 1873, and 
the corresponding mean readings of the large declination magnetometer; and in 
Table IX. are shown the same mean values of declination, corrected for the difference 
between the corresponding mean readings of the large declination magnetometer and 
the mean readings of that instrument (also given with the same Table) for the respective 
months, the corrected values thus obtained showing the mean declination of the 
several months. The adopted value of a unit of the scale of the large declination 
magnetometer is 6' 49"*5, increasing readings denoting increasing easterly declination. 
Table VIII. 
1 
Month. 
Mean Observed Declination. 
Corresponding Mean Scale-reading of large 
Declination Magnetometer. 
1867. 
1868. 
1869. 
1870. 
1871. 
1872. 
1873. 
1867. 
1868. 
1869. 
1870. 
1871. 
I 1872. 
1873. 
January 
February 
March 
April 
May 
June 
July 
August 
September 
October 
November 
December 
41 34 
41 15 
41 20 
42 18 
43 38 
43 58 
44 16 
44 2 
44 56 
43 19 
42 27 
42 24 
43 24 
43 39 
42 31 
44 51 
46 4 
45 34 
46 15 
46 56 
46 22 
45 7 
45 26 
45 38 
45 57 
45 16 
45 15 
46 29 
47 13 
47 43 
47 9 
47 4 
48 4 
46 36 
47 0 
46 54 
47 17 
46 43 
47 23 
49 15 
49 47 
50 7 
49 7 
50 18 
49 32 
48 31 
49 11 
48 37 
48 48 
49 10 
48 50 
50 6 
51 31 
51 52 
53 11 
52 43 
50 57 
50 45 
50 29 
51 6 
50 6 
51 6 
50 8 
52 46 
52 35 
52 58 
53 6 
53 2 
52 35 
53 14 
52 00 
52 20 
52 52 
51 15 
51 49 
52 46 
52 59 
53 36 
34-86 
34-80 
34-78 
34- 92 
35- 08 
35-19 
35-25 
35-30 
35-32 
3512 
3512 
35 07 
35-25 
35-21 
3514 
35-47 
35-59 
35-44 
35-55 
35-54 
35-46 
35-28 
35-38 
35-38 
35-47 
35-38 
35-46 
35-62 
35-73 
35-74 
35-70 
35 73 
35-88 
35-64 
35-67 
35-63 
35-66 
35-62 
35- 70 
36 02 
3617 
36- 22 
36-13 
36-26 
3613 
35-94 
3601 
35-92 
35-95 
35-97 
35- 97 
3610 
36- 31 
36-37 
36-59 
36-53 
36-23 
36-20 
36-17 
36-24 
3609 
36-21 
3606 
36-47 
36-44 
36-48 
36-50 
36-50 
36-47 
36-53 
36-30 
36-36 
36-41 
3616 
36-30 
36-47 
36-51 
36-64 
