80 
MAGNETIC OBSERVATIONS, 
OBSERVATIONS—Continued. 
Station. Cambridge Observatory; latitude 42° 22' 48"; longitude 4A. 44m. 29.6s. 
Needle, I?. Atop, August 9, 1850. J2ow of beginning, 5A. 40m. m. ; hour of ending, Oh. 20m. p. m. 
Observers, Prof. IF. C. Bond and Lieut. A. W. Whipple. 
o ' " 
( 47 00 
Needle vertical, face of circle north, reading of azimuth circle.__.J 47 29 
l 47 07 
( 48 26 
Needle vertical, face of circle south, reading of azimuth circle._. J 48 15 
( 48 40 
Reading of azimuth circle when plane of instrument is in the magnetic meridian.... 47 49 30 
Reading of azimuth circle when plane of instrument is in the true meridian... 38 18 45 
Approximate magnetic declination..... 9 30 45 \y. 
OBSERVATIONS FOR MAGNETIC INCLINATION AND INTENSITY—No. 2. 
Face of circle. 
Direct. 
Def. N. 40° from dip. 
o ’ 
at 34 26 
at 114 26 
Def. S. 40° from dip. 
o ' 
at 34 26 
at 114 26 
Results. 
East. 
West 
O' O' 
74 30 91 30 
74 28 : 91 30 
74 25 91 30 
74 22 91 25 
74 30 | 91 28 
74 20 i 91 28 
o ' 
57 15 
57 10 
57 10 
57 00 
57 08 
57 10 
o ' 
92 27 
92 28 
92 28 
92 30 
92 25 
92 20 
o ' 
56 15 
56 15 
56 15 
56 25 
56 15 
56 15 
N. 
S. 
0 
' 
" 
74 
25 
50 
74 
18 
40 
74 
21 
30 
Direct. 
j- By deflectors. 
Means 
74 25 50 
o 
91 
57 
28 
~08~ 
30 
50 
o ' " 
92 26 20 
56 T(T 40 
74 22 00 
Mean. 
Sum of means. 
148 37 20 
Half sum = dip , 
74 18 40 
Difference ... 
34 19 40 
Half difference, or angle of de¬ 
flection ... 
17 09 50 
O 
148 
43 
00 
0 
, 
„ 
74 
21 
30 
p 
, 
n 
36 
09 
40 
O 
' 
" 
18 
04 
50 
+ 8 48 
Index error. 
o I II 
74 30 48 
True inclination. 
