Magnetic Observations at Cambridge, United States. 
WINTER MONTHS, 
SUMMER MONTHS, 
DIURNAL OSCILLATION OF THE DECLINATION. 
41. 1842. 
143 
WINTER MONTHS. 
Mean. | Oct,|Nov,|Mean 
ie wae Dot Nor. Dec.| Jan.|Feb. | Mar. |Mean |April.| May,|/June.| July. | Aug. |Sept. of all. 
A. M. 
h, m 
0 | 6 36] 5.2 7.8/8.9] 7.2] 7.7 |10.3 | 7.8 |L0.1 |13 9 /13.9 |13.8 |16.9 | 8,1 /12.8 |5.6/2.6| 8.8 
1 | 7 36] 6.0| 8.5/7.2 13.9 | 8.9 [13.0 |14 8 /13.1 |16.4 7.5 |13.0 | 7.5 | 5.6 |10.2 
2/ 8 36} 6.8) 8.9| 8.8} 9.2| 7.7 |13.4 | 9.1 10.3 |12.4 13.7 }16.2 |15.1 | 8.9 |12.8 | 7.3] 4.0) 9.6 
3 | 9 36] 5.5) 7.5| 9.6 13.2] 8.9] 9.1 | 9.6] 9.9] 9.5 1115/64] 9-3 |8.1/65] 8.7 
4 |10 36} 4.6) 3.7/5.2| 4.8/4.9] 9.0/ 54]52) 55] 61] 80] 48/25] 53/36/21) 4.4 
5 {11 36} 0.0 | 2.3) 2.7 52| 2.5] 2.7} 1.8] 1.8] 55 1.6| 2-7 |3.5| 1.9} 2.5 
P. MM, 
6 |12 36 | 0.6| 0.0/12] 0.0/0.8} 1.5} 0.7} 1.1| 0.8] 0.5] 1.2] 0.0} 0.0] 0-6 |0.4}00) 0.0 
7 | 1 36] 0.0/1.0} 0.0 0.0] 0.2} 02} 0.0| 0.0} 1.5 0.2| 0.4 | 0.6) 0.5 | 0.2 
8 | 2 36] 0.2) 2.7/2.111.2]0.0] 0.6} 1.1] 0.0| 1.9] 1.2] 0.0} 4.1} 0.5} 13103) 2.1] 0.6 
9 | 3 36} 3.5|3.4/26 3.0 | 3.1] 13} 45] 29] 3.0 2.4| 2.8 | 0.0/3.5] 26 
10 | 4 36] 5.8) 4.7/5.2/3.5/12] 4.5 | 4.2] 2.0] 5.6] 6.0] 3210.1 |3.9/ 5.1 |2.1/0.6} 3.6 
11 | 5 36] 5.9/5.7} 7.5 69/65] 4.6] 7.0] 69! 6.0 95| 5.41/25 48 
12 | 6 36] 7.6|7.3/8.1] 4.6/3.6] 86] 6.6] 6.0] 8.0} 7.5] 5.7] 9.5 13.5] 67 13.2138] 5.7 
13 | 7 36 |10.0 | 7.0] 7.1 8.0| 8.0] 7.1 | 86] 72] 9.3 24/69 )44/3.7| 69 
14 | 8 36 |10.3 | 9.0/9.9| 7.0/5.2] 9.3] 84] 7.6] 9.9| 88/55] 8115.2] 7.5 /3.6/3.8| 68 
15 | 9 36/ 95/75/98 9.8 | 9.1] 9.7} 9.8} 88] 82 4.9| 8.3 |3.2)4.7| 7.7 
16 |10 36 /10.3 | 7.2/8.5! 7.5/7.1] 9.9 | 84] 81 /11.9| 9.5] 66] 9.6 | 4.1] 8.3 | 4.0/6.0! 7.3 
17 |11 36 | 6.9 | 6.6| 7.4 9.6 | 7.6 | 7.7 |10.0| 8.5] 7.7 5.1] 7.8 |45|/25| 68 
A. M. 
18 |12 36] 30/5.8]7.9|6.1/6.7] 9.2] 64] 7.5! 95! 98/69] 9.5 15.7| 81/21/41] 62 
19 | 1 36] 3.7/6.7/55 9.4 | 6.3} 7.9| 9.71102] 83 25| 7.7 |2.3]3.4| 6.2 
2) | 236) 76|7.5|7.7/5.7|6.6| 9.3 | 7.4] 7.5 10.1] 9.9] 7.1] 8113.5! 7.7 |2.411.6] 6.2 
21 | 3 36] 62/ 7.5/8.7 9.0 |.7.8] 7.6 |10.4| 8.9] 7.1 5.6| 7.9 | 2.9/0.8) 6.8 
22 | 4 36] 7.8/8.5/7.8)/5.4/5.2| 89 | 7.3] 8.6 |L1.0| 9.2| 5.8 112.4 |3.4| 8.4 | 4.1/1.1] 6.5 
93 | 5 36| 35/7.6/8.2 10.1 | 7.3 {10.6 14.8 '12.1| 8.4 3.5/9.9/36!08)| 7.4 
MAGNETIC DECLINATION. 
Date. A. B B. Cc. Ys D. E. &. M. 
1841. h. m. i 4m) h>, Jim, h, m. 
Oct. 26. | 147.90 | 3.11 | 14 50/280 | 2 31] 80/6 13 
Nov. 1. | 149.80 | 3.96 | 10 56]2.19 | 2 1111.34 16 35 
8. | 141.85 | 2.98 | 9 50/260 ]1 59] 72/4 1 +.050 
15. | 141.75 | 188} 9 32/201 | 2 28] 89 |6 28 
22. | 141.37 | 3.15 | 10 56/255 ]2 59] 4817 39 
29. 142.11 | 222] 10 52/154 | 0 55/1.00 |7 22 
Dec. 7.| 141.60 | 2.05 | 10 13/168 ]1 35/110 13 16 
13. | 142.10 | 1.90 | 12 12/252 ]1 53] .64 |6 45 +.012 
20. | 140.97 | 1.22 }15 0/346 ]1 15] OL |7 25 +.016 
27. | 142.00 | 2.82 | 11 29/195 12 5] 27 17 52 —.017 
1842. 
Jan. 3./ 140.80 | 254] 10 28]1.98 !1 52/222 |/o 11 +.001 
10. | 140.70 | 2.45 | 10 20] 1.89 | 2 2111.37 17 55 +.001 
17. | 14128 |. 2:70) 9 29 | 381 |'P 231.38) 1 $9") 1.05) 4 4a” —.035 
24. | 139.70 | 2.05 | 7 57]/207 | 0 35] 47 16 47 +.063 
31. | 141.60 , 3.10 | 9 56]262]1 34] 1.96 |O 128 
Feb. 7. | 139.02 | 1.45] 8 12/240]0 411.95 |7 38 
14. | 144.10 | 524] 9 13/240 ]0 34/163 |5 3) — 200 
21. | 141.10 | 228 | 6 6/121 ]0 49] 50/10 oO 
The above are the co-efficients of the formula 
D=A-+B sin (t+-2)+C sin 2 (t+7)-+D sin 3 (t-+5) 
expressing the mean diurnal curve of the week commencing with the annexed dates; t being the time, counted from 
mean noon at Gottingen. 
M is the mean hourly change, independent of solar time. To the above formula may be added, then, 
=EM (t—2h.). 
