218 THE MAG]S^ETIC DECLINATION IN PRINCE GEORGE S COUNTY 



marked by an oak stake 3 bv -i by 24 inches (T.O by 10.2 by 61 em.) 

 set almost flush with the gTonnd. 



The following trne bearings were determined : 



Cross of Episcopal church (mark) 5° 06. '8 west of north. 

 Water tank tower 2 47.2 west of south. 



With the aid of tlie tigures in the preceding table the surveyor can 

 readily ascertain tlie amount of change of the needle between any two 

 dates. For practical purposes, it will suffice to regard the change thus 

 derived as the same over the county. It should be emphasized, 

 however, that when applying the quantities thus found in the re-run- 

 ning of old lines, the surveyor should not forget that the table 

 cannot attempt to give the correction to be allowed on account of 

 the error of the compass used in the original survey. 



To reduce an observation of the magnetic declination to the mean 

 value for the day of 24 hours, apply the qnantities given in the table 

 beloAv with the sign as affixed : 



Angle, 



The angle between the true meridian line and the cupola of the 

 Southern Maryland Bank is, at the south meridian stone: 



42° 58' E. of S. 



The latitude of the Court House may be taken to be 88° 4*J .0 

 and the longtitude 76° 45'.2 W. of Greenwich or 15' E. of Wasii- 

 ingtoii. To obtain true local mean time, or solar time, subtract from 

 Eastern or Standard time,' 7 minutes. 



