MAGNETIC OBSERVATIONS. 
77 
OBSERVATIONS—Continued. 
Station, Cambridge Observatory; latitude 42° 22' 48"; longitude Ah. 44m. 20.(is. 
Needle, A. Date, August 9, 1850. Hour of beginning, 3h. 40m. p.m. ; hour of ending, 44. 6m. p.m. 
Observers, Prof. W. C. Bond and Lieut. A. IF. Whipple. 
1 47 40 
Needle vertical, face of circle north, reading of azimuth circle.-j 47 69 
( 47 45 
l 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. 4. 
Face of circle. 
Direct. 
Def. with wt. 21 gr. 
Def. with wt. 3 gr. 
Def. towards 
the vertical-. 
(1) 
Def. from the 
vertical. 
(2) 
Ther. 
Fah. 
Def. towards 
the vertical. 
(1) 
Def. from the 
vertical. 
(2) 
Ther. 
Fah. 
O ' 
74 30 
74 30 
74 15 
74 18 
74 30 
74 15 
O ' 
104 25 
104 30 
104 15 
104 00 
103 55 
104 15 
O ' 
44 22 
44 25 
44 15 
44 20 
44 30 
44 15 
o 
75 
O ' 
110 60 
110 60 
110 55 
110 58 
110 58 
110 53 
o ' 
37 15 
37 20 
37 20 
37 20 
37 22 
37 25 
o 
75 
West.-.| 
o ' " 
74 23 00 | 
O ' " 
(1) 104 13 20 ) 
(2) 44 21 10 j 
75 
O ' " 
j (1) 110 57 20 ) 
l (2) 37 20 20 j 
75 
o ' " 
59 52 10 
o ' " 
73 37 00 
Half difference, or angle of de- 
O ' " 
29 56 5 
O ' " 
36 48 30 
O ' " 
148 34 30 
O ' " 
148 17 40 
Half sum — dip.. 
O ' " 
74 17 15 
O ' " 
74 8 50 
