MARYLAND GEOLOGICAL SURVEY 481

Next follows the final table, which requires but little additional
explanation. The secular changes at the county-seats were obtained
by proper combinations of the values given in the auxiliary table, and
the values of the declination for 1900 at the county-seats were derived
from the observations made by me in 1896^l and reduced to the year
1900, as given in Table XIII. The quantities are given in degrees and
minutes for the surveyor's convenience, and being tabulated for every
five years, interpolations can readily be made. The problem con-
fronting the land surveyor, when called upon to re-run old compass
lines, has thus been simplified to the utmost. In no other state has
the information been so thoroughly systematized.

¹ The values for Rockville and Chestertown were obtained from observa-
tions made in 1897. As no observations have as yet been made at Denton,
it was necessary to adopt a value resulting from a consideration of the
observations made in the vicinity.