15 I 
MAGNETIC OBSERVATIONS. 
OBSERVATIONS—Continued. 
Station, Cambridge Observatory; latitude 42° 22' 48”; longitude ill. 44m. 29. Gs. 
Needle, B. Date, May 10, 1854. Hour of beginning, ll/(. a. m. ; hour of ending, 11/i. 30m. a. m. 
Observers, Professor W. C. Bond and Lieut. J. C. Ives. 
o > n 
( 14 48 
Needle vertical, face of circle north, reading of azimuth circle_ J 14 48 
l 14 55 
( 14 47 
Needle vertical, face of circle south, reading of azimuth circle.1 14 52 
( 14 4G 
Reading of azimuth circle when plane of instrument is in the magnetic meridian... 14 49 20 
Reading of azimuth circle when plane of instrument is in the true meridian..... 5 04 
Approximate magnetic declination-------- y 45 20 W. 
OBSERVATIONS FOR MAGNETIC INCLINATION AND INTENSITY—No. 2. 
Face of circle. 
Direct. 
N. P. needle A 400 
from dip. 
S. P. needle A 40° 
from dip. 
o ' 
at 34 25 
o ' 
at 114 25 
o ' 
at 34 25 
at 114 25 
Results. 
74 28 
East. -U 74 25 
74 21 
74 22 
West.-j I 74 28 
i 74 25 
| o / // 
Means....j 74 24 50 
Sum of means.. 
Half sum = dip. 
Differences-.-. 
Half diff. =: angles of deflection. 
o ' 
95 40 
95 38 
95 35 
95 35 
95 30 
95 30 
o ' 
53 20 
53 15 
53 15 
53 05 
53 00 
53 10 
95 34 40 
53 1<T 50 
o 
148 
45 30 
74 22 45 
42 24 50 
21 12 25 
o ' 
95 12 
95 20 
95 20 
95 40 
95 40 
95 45 
52 48 
52 55 
52 58 
53 10 
53 08 
53 15 
O 
/ 
// 
74 
24 
50 
N. 
74 
22 
45 
S. 
74 
15 
55 
Direct. 
y Bv deflectors. 
95 29 30 
53 02 20 
74 21 10 i Mean. 
148 31 50 
74 15 55 
+ 8 48 
42 27 10 
21 13 35 
74 29 58 
“0 
.2 
o > Index error. 
<3 I 
£ 
o 
O J 
True inclination. 
