MAGNETIC OBSERVATIONS. 
155 
OBSERVATIONS—Continued. 
Station, Cambridge Obsei-vatory ; latitude 42° 22' 48"; longitude 4/i. 44 m. 29.6s. 
Needle, A. Date, May 10. 1854. Hour of beginning, 11 30m. a. m. ; hour of ending, 12 m. 
Observers, Prof. W. C. Bond and Lieut. J. C. Ives. 
Needle vertical, face of circle north, reading of azimuth circle. 
Needle vertical, face of circle south, reading of azimuth circle.-.. 
Reading of azimuth circle when plane of instrument is in the magnetic meridian. 
Reading of azimuth circle when plane of instrument is in the true meridian_ 
Approximate magnetic declination...... 
o 
' 
" 
14 
52 
14 
50 
14 
45 
14 
52 
14 
50 
14 
60 
14 
51 
30 
5 
04 
00 
9 
47 
30 
OBSERVATIONS FOR MAGNETIC INCLINATION AND INTENSITY—No. 2. 
Face of circle. 
East. 
Direct. 
West 
o ' 
74 35 
74 35 
74 30 
74 30 
74 28 
74 25 
Means_ 74 30 30 
Def. N. 40° from dip. Def. S. 40° from dip. 
o ' 
at 34 25 
90 30 
90 20 
90 30 
90 20 
90 22 
90 15 
at 114 25 at 34 25 
o ' 
58 15 
58 20 
58 25 
o ' 
91 58 
91 (10 
91 57 
58 15 91 55 
58 25 j 91 58 
58 20 : 91 52 
at 114 25 
o ' 
56 55 
56 50 
56 48 
56 30 
56 40 
56 38 
Sum of means. 
Half sum = dip. 
Differences 
Half diff. angles of deflection. 
f 90 
22 
50 
\ 91 
56 
40 
} 58 
20 
00 
( 56 
43 
30 
o 
, 
n 
o 
/ 
// 
00 
42 
50 
148 
40 
10 
o 
, 
/' 
o 
, 
,, 
74 
21 
25 
74 
20 
05 
o 
, 
o 
, 
„ 
32 
02 
50 
CO 
Ox 
13 
10 
o 
, 
„ 
o 
, 
„ 
16 
01 
25 
17 
36 
35 
Results. 
o 
i 
a 
74 
30 
30 
74 
21 
25 
74 
20 
05 
74 24 03 
4- 15 04 
74 39 07 
Direct. 
j- By deflectors. 
Mean. 
-1 
5 
j-Index error. 
o 
True inclination. 
