MARYLAND GEOLOGICAL SURVEY 293 



A street a mile long, laid out in Elkton in 1800 to run north and 

 south by the compass, would, at the present time, have its north 

 terminus about 1/10 of a mile too far east! 



The above figures enable the surveyor to ascertain the precise 

 amount of change of the magnetic declination or pointing of the 

 compass between any two dates between 1700 and 1900. It should 

 be emphasized, however, that when applying the quantities thus 

 found in the re-running 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. 



In conclusion, it should be pointed out that local disturbances of 

 the compass are quite frequent in this region of Maryland, and that 

 on this account it is not possible to draw for the county the lines of 

 equal magnetic declination, without the aid of many more observa- 

 tions than contained in Table I. 



