78 
MAGNETIC OBSERVATIONS, 
OBSERVATIONS—Continued. 
Station, Cambridge Observatory; latitude 42° 22' 48”; longitude 4 h. 44m. 29. 6s. 
Needle, A. Date, August 9, 1850. Hour of beginning, 12 h. 25 m. p. m. ; hour of ending, 1 h. 25 m. p. in. 
Observers, Prof. TF C. Bond and Lieut. A. IF. Whipple. 
o ' " 
( 47 40 
Needle vertical, face of circle north, reading of azimuth circle. J 47 69 
( 47 45 
( 47 70 
Needle vertical, face of circle south, reading of azimuth circle... } 47 70 
( 47 67 
Reading of azimuth circle when plane of instrument is in the magnetic meridian.. 48 00 10 
Reading of azimuth circle when plane of instrument is in the true meridian... 38’ 18 45 
Approximate magnetic declination______ 9 41 25 W. 
OBSERVATIONS FOR MAGNETIC INCLINATION AND INTENSITY—No. 2. 
Face of circle. 
East. 
West. 
Means.. 
Sum of means 
Half sum := dip. 
Difference. 
Direct. 
o ' 
74 ’ 30 
74 30 
74 15 
74 18 
74 30 
74 15 
Def. 
N. 40° from dip. 
Def. S. 40° from dip. 
Ke suits. 
o 
' 
o 
o 
' 
o 
' 
at 34 23 
at 114 23 
at 34 
23 
at 114 23 
o 
/ 
o 
, 
o 
, 
o 
, 
O 
„ 
90 
63 
57 
35 
92 
37 
56 
00 
74 
23 
00 
Direct. 
90 
65 
57 
30 
92 
37 
56 
02 
90 
62 
57 
37 
92 
35 
56 
05 
N. 
S. 
74 
74 
17 
16 
10 
15 
j- By deflectors. 
90 
60 
57 
32 
92 
28 
56 
00 
90 
55 
57 
35 
92 
28 
56 
00 
90 
55 
57 
37 
92 
28 
55 
55 
o ' » 
74 23 00 
91 00 00 
o ' 
92 32 
57 34 
20 
( 56 
10 
00 20 
74 18 48 | Mean. 
o ' " o ' 
148 34 20 148 32 
30 
o ' 
74 17 
10 
o ' 
74 16 
15 
o ' 
33 25 
40 
o ' 
36 31 
50 
Half diff. or angle of deflection. 
o ' 
16 42 
50 
o ' 
18 15 
55 
+ 15 04 
o ^ Index error. 
O 
J 
74 33 52 
True inclination. 
