78 MAGNETIC OBSERVATIONS. 
OBSERV ATIONS— Continued. 
Station, Cambridge Observatory ; latitude 420 22' 48"; longitude 4h. 44m. 29. 6s. 
Needle, A. Date, August 9, 1850. Hour of beginning, 12h. 25m. p. m. ; hour of ending, 1h. 25m. p. m. 
Observers, Prof. W. C. Bond and Lieut. A. W. Whipple. 
O , " 
47 40 
Needle vertical, face of circle north, reading of azimuth circle 47 69 
. 47 45 
47 70 
Needle vertical, face of circle south, reading of azimuth circle 47 70 
; 47 67 
Reading of azimuth circle when plane of instrument is in the magnetic idi 48 00 10 
Reading of azimuth circle when plane of instrument is in the true meridian 88. 18 45 
Approximate magnetic declination 9... 41. 25: W. 
OBSERVATIONS FOR MAGNETIC INCLINATION AND INTENSITY—No. 2. 
Def. N. 40° from dip. | Def. S. 40° from dip. 
Face of circle. Direct. | | | Results. 
e ed Our Sp | E E 
at 34 23 |at 114 23 | at 34 23 | at 114 23 
o , o 7 o d o , O r O , " 
74 30 90 63 57 35 92 37 56 00 š 
- Fast TA 30 | 90 65 | 57 30 | 92 37 | 56 02 19 ہی 09 ہے‎ 
74 15 90 602 51 7 92 35 56 05 
b "s D a z (By deflectors. 
; 74-48 90 60 57 532 92 56 00 
Wetton 2592 2 74 30 90. 55 Dt. 35 92 56 00 
74 15 90 55 57 87 92 28 55 
fy 0 ۴ " o , ” fe) , " 
ara e 91 00 00 92 32 10 74 18 48 Mean 
Means 74 23 00 —— 
| 57 34 20 56 00 20 
| 
° , ” , ” 
Sum of means 148 34 20 148 82 30 
š 
[e] , ” 0 , ” 2 | f 
Maras N e 1t . de E HM + +15 04 S | Index error. 
= 
Š š S = 
3) 
2 ies [e] , " Oo , " 
Difference e 33 25 40 36 3i 50 
| 1 یز‎ o T » | o di " ° , ” 
Half diff. or angle of deflection... 16 42 50 18 15 55 74 33 52 | True inclination. : 
