Vertical Component of Magnetic Force. 239 
TABLE XV.— Continued. 
Civil 
Day. 
January. 
February. 
March. 
April. 
May. 
June. 
July. 
August. 
September. 
October. 
November. 
December. 
0-01 
0-01 
O'Ol 
O'Ol 
0*01 
O'Ol 
0*01 
001 
001 
O'Ol 
O'Ol 
0-01 
20 
6980 
6689 
6371 
6171 
6025 
5945 
5849 
[6049] 
5437 
5417 
5254 
5169 
21 
6972 
6671 
6314 
6173 
[5959] 
5973 
5713 
6117 
5242 
5415 
5258 
5173 
22 
[6853] 
6677 
6358 
6144 
5927 
5883 
5819 
6244 
5325 
[5356] 
5188 
5169 
23 
6700 
6690 
6294 
[6070] 
5905 
5953 
[5925] 
5391 
5300 
5279 
5147 
24 
6712 
6981 
6330 
5971 
5920 
5999 
5742 
[5385] 
5344 
5292 
[5163] 
25 
6870 
6658 
6275 
5956 
5917 
[5981] 
6619 
5921 
5461 
5460 
5337 
5087 
26 
6878 
[6718] 
[6252] 
6005 
5778 
6008 
5805 
5866 
5502 
5649 
[5287] 
5159 
27 
6787 
6705 
6235 
6037 
5930 
6014 
5670 
[5805] 
5389 
5596 
5243 
5247 
28 
7000 
6651 
6164 
6049 
[5888] 
6030 
5683 
5748 
5396 
5469 
5301 
5314 
29 
[6860] 
6216 
5990 
5900 
6050 
5773 
5686 
5449 
[5557] 
5269 
5184 
30 
,6833 
6105 
[5993] 
5868 
6035 
[5701] 
5609 
5141 
5626 
5282 
5207 
31 
6833 
6025 
5932 
5702 
5652 
5532 
[5206] 
Means. 
6940 
6758 
6157 
6153 
5968 
5997 
5875 
5757 
5405 
5373 
5332 
5207 
Table XV. was formed in the following manner ; the means of the balance micrometer readings, corrected 
for temperature, were first obtained for each civil day, and these means were reduced to parts of the vertical 
component by the following formula? : — 
January 1 — August 22. /= n x 0-000009 
August 25— August 31. /= (ra — 160) 0-000009 
September 6— November 11. f=(n- 222) 0-000009 
November 14 — December 31. / = (» - 260) 0-000009 
Where / is the quantity in the previous Table and n the mean micrometer reading corrected for tempera- 
ture. 
The balance needle was removed three times in 1843 for the purpose of determining its temperature correc- 
tion, namely, on August 23 and 24, on September 1, 2, 3, 4, and 5, and on November 13. These removals neces- 
sarily broke the series of observations, but it is conceived that the different portions after August have been 
reduced to nearly the values which they would have had, had there been no removal, by the following methods : — 
1st, To connect the observations after November 13, with those immediately before it, — 
Mean of the micrometer readings, week, Oct. 16 — 21. = 830-3 
Oct. 23— 28. ---- 829-8 
Oct. 30— Nov. 4. = 829-7 1 n , • , A A f - 0*6 
Nov. 6- 11. = 814-8 ] Chan - e m 14 d ^ s = ( - 15-0 
period, Oct. 16 — Nov. 11. = 826-1, before adjustment. 
The mean corresponding to October 30 is, therefore, 826-1, and the mean change for 14 days being — 7"8, 
the mean corresponding to November 13 will be 818-3. 
Mean of micrometer readings, week, Nov. 14 — 18. = 858-3 
Nov. 20— 25. = 845-3 
Nov. 27— Dec. 2. = 848 8 1 ni .. r ' f - 9-5 
Dec. 4- 9. = 837-3 j Cha ^ e m 14 d ^ S= { - 8-0 
period, Nov. 14 — Dec. 9. = 847*4, after adjustment. 
The mean corresponding to November 27 is, therefore, 847'4, and the mean change for 14 days being 
— 8*7, the mean corresponding to November 13 will be 856*1. This gives nearly 38-0 micrometer divisions 
more than the previous result ; 38-0 was therefore subtracted from all the daily means in micrometer divisions 
after November 13, 1843. 
