FIRST REPORT UPON MAGNETIC WORK
IN MARYLAND.

INCLUDING

THE HISTORY AND OBJECTS OF MAGNETIC

SURVEYS

INTRODUCTION.

A detailed magnetic survey of Maryland was conducted during
1896 by the writer under the auspices of the Maryland Geological
Survey. The matter herewith presented forms the first part of a com-
plete report on this work.

As it was made a special object to obtain the data that would be
of direct benefit to the practical needs of the land surveyor of Mary-
land, this first report has been prepared with this object in view. The
present communication must therefore treat primarily of the mag-
netic declination, its variation with time and locality. The require-
ments of a magnetic survey as regarded from the standpoint of the
geologist and of the magnetician have, however, not been neglected.
The presentation of the complete observations, their final reduction
and discussion must be reserved, however, for future reports.

In addition to the funds provided by the Geological Survey, a small
grant was made by the American Association for the Advancement of
Science at the Buffalo meeting of 1896, for the purpose of " carrying
on investigations on terrestrial magnetism in connection with the
magnetic survey of Maryland. " Additional data were also obtained
in connection with the establishment of meridian lines at some of the
county-seats, the cost of such lines being, according to the laws of
Maryland, defrayed by the several counties themselves.

The entire instrumental outfit was courteously furnished by the