MAGNETIC DECLINATION AT BOMBAY. 
377 
values of the coefficients A,, B 1? A 2 , B 2 , A 3 , B 3 , &c. This has been done for the mean 
s olar-diurnal variation for each month of the year, and also for each half year in the 
period 1859 to 1865, with results as shown in the following Tables: — 
Table XIY. — Showing the calculated values of the coefficients A„ B„ A 2 , B 2 , A 3 and B 3 
in the series ( y ) which expresses the mean solar-diurnal variation for each month 
of the year, for the whole year, and for different half years*. 
Months. 
Values of the coefficients of the first three pairs of terms of the series ((/). 
A r 
B r 
a 2 . 
b 2 . 
a 3 . 
b 3 . 
January 
February 
March 
April 
May 
June 
July 
August 
September 
October 
November 
December 
+0-147 
-0060 
-0-407 
-0-908 
-1-038 
-1-271 
— 1-151 
-1 123 
-0-910 
-0 305 
+0-183 
+0-250 
+0028 
-0-003 
-0-175 
+0-048 
+0-044 
-0011 
-0130 
+0160 
+0-230 
+0063 
+0-200 
+0-225 
-0-247 
-0221 
-0-267 
-0-097 
+0-197 
+0-090 
+0-102 
+0-296 
+0-300 
+0-032 
-0091 
-0-046 
+0-025 
+0034 
+0-367 
+0-828 
+ 1057 
+1-119 
+ 1 018 
+ 1-262 
+ 1-090 
+0-379 
-0-187 
-0-196 
+0-183 
+0-187 
+0-535 
+0-799 
+0-839 
+0-777 
+0-700 
+0-898 
-1-0-943 
+0-573 
+0076 
+0013 
+0-202 
+0-184 
+0-220 
+0153 
-0051 
+0-075 
+0059 
-0 059 
-0-096 
-0040 
+0019 
+0-082 
Year 
-0 549 
+0-057 
+0004 
+0-566 
+0-544 
+0062 
g ( April to September . . . 
g | October to March . . . 
-1-067 
-0 032 
+0-057 
+0-056 
+0148 
-0140 
+ 1-062 
+0070 
+0-826 
+0 261 
+0-013 
+0-111 
January to June 
Jij ( July to December . . . 
-0-589 
-0-509 
-0 011 
+0-125 
-0091 
+0-099 
+0-572 
+0-561 
+0-553 
+0-534 
+0-130 
-0 006 
Table XV. — Showing the calculated values of the coefficients A,, B,, A 2 , B 2 , A 3 and B 3 
in the series ( y ), which expresses the mean solar-diurnal variation for each half year, 
April to September and October to March, in the period 1859 to 1865. 
Years. 
Values of the coefficients of the first three pairs of terms of the series (y). 
A r 
Bj. 
A 2 . 
b 2 . 
A- 
b 3 . 
April to j 
September, j 
f 1859... 
1860... 
1861... 
1862... 
I 1863... 
1864... 
( 1865... 
— 1-183 
— 1 168 
-1-084 
-0-996 
-1-040 
-1-029 
-0-967 
-0-007 
+0046 
+0-085 
+0-042 
+0088 
+0-048 
+0-096 
+0-037 
+0-138 
+0-217 
+0-216 
+0-158 
+0 139 
+0-133 
+ 1-230 
+1-308 
+ 1125 
+0-989 
+0-973 
+0-952 
+0-857 
+0-916 
+0-954 
+0-882 
+0-823 
+0-760 
+0-766 
+0-681 
+0073 
+0020 
-0-028 
-0-043 
+0041 
+0 030 
+0-001 
October to j 
March. ' 
f 1859... 
1860... 
| 1861... 
; 1862... 
1863... 
| 1864... 
^ 1865... 
-0-141 
-0102 
-0073 
-0033 
+0-037 
+0-006 
+0-079 
-0-103 
-0107 
+0-028 
+0 042 
+0076 
+0147 
+0-309 
-0-300 
-0-266 
-0151 
-0045 
-0 147 
-0096 
+0 031 
+0043 
+0058 
+0-165 
+0048 
+0031 
+0-022 
+0-127 
+0-246 
+0-288 
+0-294 
+0-268 
+0-237 
+0223 
+0272 
+0141 
+0-188 
+0-143 
+0 053 
+0-141 
+0-108 
+0-002 
The curves (Nos. 31 to 33, Plate XXVIII.) are constructed to exhibit the variations, 
in magnitude and direction, of the resultants of A, and B,, A 2 and B 2 , A 3 and B 3 respec- 
tively ; O being the centre of coordinates, the A coefficients are set off in a vertical direc- 
tion, upward if positive, and the B coefficients in a horizontal direction, to the right if 
positive, so that the distances from O to the points marked 1, 2, 3, &c. to 12 and ©r 
* Gottingen time was inadvertently used instead of Bombay time in the calculation of the coefficients 
A,, Bj, &c. 
MDCCCLXIX. 3 E 
