MAGNETIC OBSERVATIONS, 
153 
OBSERVATIONS—Continued, 
Station, Cambridge Observatory , Mass.; latitude 42° 22' 48’'; longitude 4A. 44A. 29.6s. 
Needle, 11. Date, May 10, 1854. Hour of beginning, 10A. a. m. ; hoar of ending, 11A. a. m. 
Observers, Professor W. C. Bond and Lieut. J. C. Ives. 
o ' u 
C 14 48 
Needle vertical, face of circle north, reading of azimuth circle_< 14 48 
( 14 55 
f 14 47 
Needle vertical, face of circle south, reading of azimuth circle.< 14 52 
( 14 46 
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....... 9 45 20 W. 
OBSERVATIONS FOR MAGNETIC INCLINATION AND INTENSITY—No. 2. 
Face of circle 
East. 
West 
Means 
Sum of means . 
Half sum = dip . 
Differences, 
Def. N. 40° from dip. 
Direct. 
o ' 
at 34 25 
o ' 
74 28 
74 25 
74 21 
74 22 
74 28 
74 25 
o / " 
74 24 50 
o / 
90 45 
90 55 
90 50 
90 40 
90 45 
90 45 
o ' 
at 114 25 
o / 
57 45 
57 48 
57 50 
57 50 
57 50 
57 52 
° 
/ 
// 
o 
/ 
// 
( 90 
46 
40 
C 91 
43 
00 
( 57 
49 
10 
( 56 
48 
20 
o 
/ 
II 
o 
1 
II 
148 
35 
50 
148 
31 
20 
74 17 55 
32 57 30 
O i n 
Half diff. =; angles of deflection j 16 28 45 
Def. S. 40° from dip. 
o ' 
at 34 25 
o ' 
91 40 
91 45 
91 40 
91 45 
91 40 
91 48 
at 114 25 
o / 
56 45 
56 40 
56 45 
56 55 
56 50 
56 55 
74 15 40 
34 54 40 
o ' " 
17 27 20 
Results. 
o 
/ 
// 
74 
24 
50 
74 
17 
55 
74 
15 
40 
Direct. 
■ By deflectors. 
74 19 28 
+ 8 48 
74 28 16 
Mean. 
*0 
§ | 
o } Index error. 
S I 
S J 
True inclination. 
20 m 
