The discovery of the magnetic needle was a boon to mankind, and has been
of inestimable service in guiding the mariner through trackless waters,
and the explorer over desert wastes. In these, its legitimate uses, the
needle has not a rival, but all efforts to apply it to the accurate
determination of permanent boundary lines have proven very
unsatisfactory, and have given rise to much litigation, acerbity, and
even death.
For these and other cogent reasons, strenuous efforts are being made to
dispense, so far as practicable, with the use of the magnetic needle
in surveying, and to substitute therefor the more accurate method of
traversing from a true meridian. This method, however, involves a
greater degree of preparation and higher qualifications than are
generally possessed, and unless the matter can be so simplified as to be
readily understood, it is unreasonable to expect its general application
in practice.
Much has been written upon the various methods of determining, the
true meridian, but it is so intimately related to the determination of
latitude and time, and these latter in turn upon the fixing of a true
meridian, that the novice can find neither beginning nor end. When to
these difficulties are added the corrections for parallax, refraction,
instrumental errors, personal equation, and the determination of the
probable error, he is hopelessly confused, and when he learns that time
may be sidereal, mean solar, local, Greenwich, or Washington, and he is
referred to an ephemeris and table of logarithms for data, he becomes
lost in "confusion worse confounded," and gives up in despair, settling
down to the conviction that the simple method of compass surveying is
the best after all, even if not the most accurate.
Having received numerous requests for information upon the subject, I
have thought it expedient to endeavor to prepare a description of the
method of determining the true meridian which should be sufficiently
clear and practical to be generally understood by those desiring to make
use of such information.
This will involve an elementary treatment of the subject, beginning with
the