374 A. D. Bache on the Horizontal Component of Magnetic Force. 



night to midnight. Increase of scale readings correspond to de- 

 crease of horizontal force. One scale division was equivalent 

 to 365 ten millionths of the force, or, in absolute measure to 

 1524 ten millionths, the mean horizontal force being, in absolute 

 measure 4-176. Proper weights, according to the number of 

 observations were given to the results for the even and odd 

 hours. 



The tables given in the memoir contain the hourly normals 

 for each month of the five years, and for the mean, reckoned in 

 scale divisions, and reduced to the standard temperature of 63° 

 Fahrenheit and corrected for irregularities in the progressive 

 change. The numbers there contain the regular progressive 

 and secular changes. 



From these detailed tables are formed the following:— 



The following table contains 

 for each month and season, reckoning as the summer season, 

 the half year from April to September inclusive, and as the win- 

 ter, the months from October to March inclusive. 



