78 MR BROUN ON THE BALANCE MAGNETOMETER. 
TABLE VII. 
Determination of the Temperature Correction for the Bifilar Magnetometer, from 
comparisons of the Daily Observations. 
Value of q 
Preceding temperatures greater than Preceding temperatures less than Mean of the | ; 
the succeeding. the succeeding. two values of ofthe aanae 
q A(t 
PERIOD. nee ( ) 
TA(t) | ZA (x) ZA SA(x) | q ine | “ee 
1844. - Se. Div. - Se. Div. | Se. Div. 
May 9—24. 5384.9 13066.8 , 2359.9 4033.0 | 1.71 | 0.000270 | 0.000289 
May 29—June 28. | 11938.2 24597.2 : 26719.2 45966.3 | 1.72 | 0.000246 | 0.000238 
July 17—30. 1843.1 3004.0 : 4637.8 8470.4 | 1.83 | 0.000225 | 0.000230 
Sept. 2—25. 27322.6 58684.3 : 622.1 1260.8 | 2.03 | 0.000259 | 0.000255 
Nov. 26—Dec. 13 | 17855.4 36791.6 J 2143.7 3104.5 | 1.45 | 0.000229 | 0.000259 
| —_— 
For all the periods, | 64294.2 |131143.9 | 2. 36482.7 62835.0 | 1.72 | 0.000244 


When it is considered that the daily range of the Bifilar readings, in parts of 
the whole horizontal force, is to the daily range of the Balance readings, in parts 
of the whole vertical force, as 7 or 8 to 1, it will be seen that the results for the 
Bifilar magnetometer are equal to those for the Balance. It should also be remem- 
bered that the results for May and July are from short periods. 
The results obtained by deflections on two days were 0.000291 and 0.000298, 
the partial results agreeing very well. 
Taking into account the expansion of the wires, the total temperature cor- 
rection is 0.000304. 
It will be observed, in this case, that the results by deflections are greater 
than those from a comparison of the daily observations. 
MAKERSTOUN, April 18. 1845. 
