MAGNETIC OBSERVATIONS. 
79 
OBSERVATIONS—Continued. 
Station, Cambridge Observatory; latitude 42° 22'48"; longitude 4 h. 44 m. 29.6s. 
Needle, A. Date, August 9, 1850. Hour of beginning, 4 h. 15 m. p. m. ; hour of ending, 4 h. 30 m. p. m. 
Observers, Prof. W. C. Bond end Lieut. A. W. Whipple. 
o ' " 
f 47 40 
Needle vertical, face of circle north, reading of azimuth circle. ...... I 47 69 
( 47 45 
1 47 70 
Needle vertical, face of circle south, reading of azimuth circle----I 47 70 
( 47 67 
Reading of azimuth circle when plane of instrument is in magnetic meridian_ 48 00 10 
Reading of azimuth circle when plane of instrument is in true meridian_ 38 18 45 
Approximate magnetic declination___ 9 41 25 W. 
OBSERVATIONS FOR MAGNETIC INCLINATION AND INTENSITY—No. 3. 
Face of circle. 
Direct. 
Def. S. at app. dip. 74° 23'. 
Def. towards 
the vertical. 
Def. from the : T1 er. 
vertical. ! Fahr. 
Def. N. at app. dip. 74° 23'. 
Def. towards 
vertical. 
Def. from the 
vertical. 
Ther. 
Fahr. 
East i 
West. 
Means. 
Sum 
Half sum — dip. 
Difference. 
74 30 
74 30 
74 15 
74 18 
74 30 
74 15 
Half difference, or angle of de¬ 
flection _ 
o ' 
108 18 
108 28 
108 15 
108 28 
108 28 
108 28 
o ' 
40 10 
40 10 
40 15 
40 17 
40 20 
40 05 
74 23 00 
108 24 10 
40 12 50 
148 37 00 
74 18 30 
68 11 20 
34 05 40 
o 
75 
o ' 
105 07 
105 05 
105 15 
105 00 
105 00 
104 55 
o ' 
43 35 
43 35 
43 33 
43 22 
43 28 
43 23 
105 03 40 
43 29 20 
148 33 00 
o / // 
74 16 30 
61 34 20 
30 47 10 
o 
75 
