Vertical Component of Magnetic Force. 



239 



TABLE HY .—Continued. 



!^ivil 

 Day. 



January. 



February. 



March. 



April. 



May. 



June. 



July. 



August. 



September. 



October. 



November. 



December. 





0-01 



0-01 



O-Ol 



0-01 



n-oi 



0-01 



0-01 



01 



001 



0-01 



0-01 



o-ni 



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] 



eans. 



6940 



6758 



6457 



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 temperatiu-e, were first obtained for each civil day, and these means were reduced to parts of the vertical 

 component by the following formulae : — 



January 1 — August 22. /= n x 0-000009 



August 25— August 31. /= (»^ - 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. = 829-71 riT, ■ t a a f - 0-6 



Nov. 6- 11. = 814-8] ^^^°g"^"l*^^y^=(- 15-0 



period, Oct. 16 — Nov. 11. = 826-1, before adjustment. , 



The mean con-esponding 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. = 8488 1 ^, . i . , f - 9-5 



Dec. 4- 9. =837-3]^^^^'"g""'^*'^^y'=(-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. 



