156 MAGNETIC OBSERVATIONS。 
OBSERV ATIONS— Continued. 
Station, Cambridge Observatory ; latitude 420 22' 48" ; longitude 4h. 44m. 29. 6s. 
Needle, A. Date, May 10, 1854. Hour of beginning, 12h. m. ; hour of ending, 12h. 30m. p. m. 
Observers, Prof. W. C. Bond and Let, J. C. Ives. ` 
[e] H " ۴ 
14 52 
Needle vertical, face of circle north, reading of azimuth circle 14 50 
14 45 
14 52 
Needle vertical, face of circle south, reading of azimuth circle 14 50 
E 14 60 
Reading of azimuth circle when plane of instrument is in the magnetic meridian...........-....- 14 51 30 | 
Reading of azimuth circle when plane of instrument is in the true meridian. 5 04 00 d 
Approximate magnetic declination 9 47 30W. š 
OBSERVATIONS FOR MAGNETIC INCLINATION AND INTENSITY—NOo. 2. 
N. P. needle B 409 | S. P. needle B 400 
from dip. from dip. 
Face of circle. Direct. 
Results. 
0 d o 1 o 2 
at 34 25 |at 114 25 | at 34 25 |at 114 25 
° 1 o , o , o 1 o , o , Hi 
74 35 96 50 bl 45 94 50 53 45 
East T4 35 96 48 51 48 94 48* 40 74 30 30 Direct. 
74 30 96 58 51 45 94 55 40 
N.| 74 12 40 
3 74 14 40 | By deflectors. 
T4 30 96 25 51 50 94 38 53 50 
West. 74 28 96 25 51 50 94 40 53 40 
74 25 96 20 51 48 94 50 3 40 
o 1 H o , Dr o H ” 
96 37 40 94 46 50 14 19 17 Mean. 
MEME i.e ccs 74 30 30 ` 
51 47 40 53 4 0 
o , ” ° I ” E 
Sum of means 148 25 20 148 29 20 + 15 04 € {Index error. 
3 
o 
o š ” ° 1 7 
e T4 12 40 74 14 40 
: | 
: o , " o , " | 
Differences. _ 44 57 00 41 04 20 
š = ° , ” 9 / tr ° 1 , 
Half diff. — angles of deflection-| 14. 38 . 0 20 M..14: | 74 34 21 True inclination. 
4 | 
