ON THE MAGNETIC SURVEY OP ENGLAND. 



269 



The values of the total force at the several stations derived by the abso- 

 lute and by the statical methods are collected in Table XII., together with 

 the latitudes and longitudes of the stations. 



Table XII. 



Table XIII. — Differences in the values of (j> by the Absolute and Statical 

 Methods at Stations where both methods were employed. 



Sum of the + differences, -078; sum of the — differences, "094; excess of — differences, 

 •016 in 12 determinations ; or -ooi on the average, being about one ten-thousandth of the 

 Vfhole force. 



The mean latitude of the 24 stations in Table XII. is 52° 13', and the 

 mean longitude 1° 38' VV. The mean force at the central position is 10'332=(p'. 

 Tiie stations, and the adopted values of cp, contained in Table XII. being com- 

 bined in the usual manner, give (m) the angle which the isodynamic lines 

 make with the meridian= — 57°35'-7, (or their direction is from N. 57°35'-7 

 E. to S. 57°35'*7 W. ;) and r, or the rate of increase of the total force is a 



