80 d. ۱ MAGNETIC OBSERVATIONS. 
! 
OBSERVATIONS—Continued. | 
Station. Cambridge Observatory ; latitude 420 22' 48" ; longitude 4h. 44m. 29.065. 
Needle, B. Date, August 9, 1850. Hour of beginning, 5h. 40m. p. m. ; hour of ending, 6h. 20m. p. m., 
Observers, Prof. W. C. Bond and Lieut. A. W. Whipple. 
[9] , ” 
47 00 | 
Needle vertical, face of circle north, reading-of azimuth circle 47 29 ۱ 
47 07 
48 26 
Needle vertical, face of circle south, reading of azimuth circle AR 15 
48 40 
Reading of azimuth circle when plane of instrument is in the magnetic meridian 47 49 30 
Reading of azimuth circle when plane of instrument is in the true meridian 38 18 45 
Approximat gnetic declination 9 30 45W. | 
OBSERVATIONS FOR MAGNETIC INCLINATION AND INTENSITY—No. 2. 
Def. N. 409 from dip. | Def. S. 40? from dip. 
Face of circle. Direct. - Results. 
oF QT 4 (e E ۲ | 
at 34 26 | at 114 26 | at 34 26 | at114 26 | 
ny [o] 7 [e] 9 fe) 7 ° , ° , [o] ۶ n 
T4 0 94. 74 92 97 56 15 ۴ 
East 74 28 | 91 30 | 57 10 | 92 28 | 56 15 74 25 50 | Direct. 
74 25 91 30 57 10 92 28 56 15 
m 2 
-I 
Dë 
s, 
oo 
40 | 
74 21 30 d deflectors. Ra 
Wott ees] 74 30 91 28 57 08 92 25 56 15 
Ow» ERAS , " o , e o 4 gé 
m-or 39 92 . 20 20 74. 22 00 Mean 
NOME. tu pa iae 74 25 50 一 一 —— 
57 و‎ .50 DE” 18. 40 
۱ o , او‎ ^ [e] , ” 
Sum of means 148 37 20 148 43 00 
i x 
ie 
= 
$ O " [o] 2و٦‎ " += 
. . Index error. 
Half sum 一 dip 74 18 40 4-9 59 TEM Ë j 
| | E 
fo] , ” ° , ” | 
Difference d 34 19 40 36 09 40 
x 0 7 " O , m [9] ۳ “ 
Half difference, or angle of de- | 
flection - ER 17 09 50 18 04 50 74 30 48 True inclination. 
