NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Manual calculation of compass variation
From: Frank Reed CT
Date: 2004 Oct 16, 16:35 EDT
From: Frank Reed CT
Date: 2004 Oct 16, 16:35 EDT
From the preface to the online version of the official journal:
"Cook was assiduous in obtaining observations to ascertain the Variation
of the compass--i.e., the difference between the direction shown by the
magnetic needle and the true north. He is constantly puzzled by the
discrepancies in these observations made at short intervals. These arose
from the different positions of the ship's head, whereby the iron within
a certain distance of the compass is placed in different positions as
regards the needle working the compass card, the result being that the
needle is attracted from its correct direction in varying degree. This is
known as the Deviation of the compass. The cause of this, and of the laws
which govern it, were only discovered by Captain Flinders in 1805.
Happily for the navigators of those days, little iron entered into the
construction of ships, and the amount of the Deviation was not large,
though enough to cause continual disquiet and wonderment."
Frank R
[ ] Mystic, Connecticut
[X] Chicago, Illinois
"Cook was assiduous in obtaining observations to ascertain the Variation
of the compass--i.e., the difference between the direction shown by the
magnetic needle and the true north. He is constantly puzzled by the
discrepancies in these observations made at short intervals. These arose
from the different positions of the ship's head, whereby the iron within
a certain distance of the compass is placed in different positions as
regards the needle working the compass card, the result being that the
needle is attracted from its correct direction in varying degree. This is
known as the Deviation of the compass. The cause of this, and of the laws
which govern it, were only discovered by Captain Flinders in 1805.
Happily for the navigators of those days, little iron entered into the
construction of ships, and the amount of the Deviation was not large,
though enough to cause continual disquiet and wonderment."
Frank R
[ ] Mystic, Connecticut
[X] Chicago, Illinois
