76 
MAGNETIC OBSERVATIONS. 
OBSERVATIONS WITH FOX’S MAGNETIC INCLINATION AND INTENSITY INSTRUMENT. 
Station, Cambridge Observatory; latitude 42° 22' 48"; longitude 41i. 44«. 29. 6.s. 
Needle , C. Date , August 9, 1850. Hour of beginning, 11 A. a. m.; hour of ending, 11 h. 15 m. a. m. 
Observers, Prof. W. C. Bond and Lieut. A. W. Whipple. 
o / /, 
f 47 49 
Needle vertical, face of circle north, reading of azimuth circle.47 47 
( 47 47 
t 47 26 
Needle vertical, face of circle south, reading of azimuth circle.-.7 47 55 
( 47 70 
Beading of azimuth circle when plane of instrument is in the magnetic meridian-- 47 49 00 
Reading of azimuth circle when plane of instrument is in the true meridian. 38 18 45 
Approximate magnetic declination.....-. 9 30 15 W. 
OBSERVATIONS FOR MAGNETIC INCLINATION—No. 1. 
Face of circle. 
With marked end of needle, N. 
pole. 
Thermom. 
Fahrenh’t. 
With marked end of needle, S. 
pole. 
Thermom. 
Fahrenh’t. 
North end of 
needle reads— 
South end of 
needle reads— 
North end of 
needle reads— 
South end of 
needle reads— 
0 ' " 
74 40 
74 30 
74 28 
74 31 
74 33 
74 33 
0 ' » 
74 55 
74 35 
74 30 
74 28 
74 30 
74 28 
O 
75 
O ' » 
74 28 
74 38 
74 40 
74 32 
74 30 
74 30 
0 ' " 
74 23 
74 45 
74 45 
74 35 
74 35 
74 30 
b 
75 
Vest .| 
Means_ 
74 32 30 
74 34 20 
75 74 33 00 
74 35 30 
75 
Mean of four results. 
74° 33' 50" 
Station, Cambridge Observatory ; latitude 42° 22' 48"; longitude ill. 4 4m. 29. 63. 
Date, August 9, 1850. Hour of beginning, 10 h. 25 m. a. rn. ; hour of ending, 10 k. 45m. a. in. 
Reading of azimuth circle when plane of instrument is in the true meridian 
Face west. 
Face east. 
{ 
I 
Mean_____;__- „_„ „___ 
Needle (C) vertical, face of circle north, reading of azimuth circle hy a mean of five observations_ 
Needle (C) vertical, face of circle south, reading of azimuth circle hy a mean of five observations.. 
Reading of azimuth circle when plane of instrument is in the magnetic meridian--- 
Reading of azimuth circle when plane of instrument in the true meridian--------- 
o 
85 
10 
85 
14 
85 
10 
85 
15 
85 
12 
15 
93 
53 
12 
95 
31 
48 
94 
42 
30 
85 
12 
15 
Approximate magnetic declination 
9 30 15 W. 
