MARYLAND GEOLOGICAL SURVEY 511

entirely beyond the disturbing influence of some artificial cause near
the place where by law the line had to be established, special mag-
netic observations were made at some point near the town where
there was no reason to suspect a local disturbance and the result of
these observations likewise furnished to the county commissioners.

The Frederick and Wicomico lines were established in the fall of
1896 and the remainder in the spring of the present year. More
detailed reports of each line have been prepared and sent to the
respective county commissioners and will, doubtless, be published
in some other connection.

Numerous inquiries have been received by the Maryland Geological
Survey with regard to simple methods for the determination of true
meridian lines—such methods as could be employed with the average
instrumental equipment of the surveyor.

In the hope that the furnishing of this information to the surveyor
will be instrumental in inducing him to determine the magnetic de-
clination or " variation of the compass " more frequently than is his-
custom, I take pleasure in complying with the requests for this infor-
mation .and have accordingly added the following article.

The method used in the magnetic survey—that of determining
the true bearing of some distant mark by solar observations—while
more expeditious for the work of the survey is not one that the
surveyor in general can employ with success. I have therefore
omitted an explanation of this method.

SIMPLE METHODS FOR DETERMINING A TRUE MERIDIAN LINE.'

I.—TO DETERMINE THE TRUE MERIDIAN BY OBSERVATION ON POLARIS AT
ELONGATION WITH THE ENGINEER'S OR SURVEYOR'S TRANSIT.

1. Set a stone, or drive a wooden plug, firmly in the ground and
upon the top thereof make a small distinct mark.

2. About thirty minutes before the time of the eastern or western

¹ The descriptions of the four methods given under this heading are
borrowed almost entirely verbatim from the U. S. Land Office Manual of Sur-
veying Instructions, Washington, 1896. I have made a few revisions and have
referred the tables to the present year.—L. A. B.