78 



MR BROUN ON THE BALANCE MAGNETOMETER. 



Table YII. 



Determination of the Temperature Correction for the Bifilar Magnetometer, from 

 comparisons of the Daily Observations. 



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 0.000208, 

 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. 



