IMPROVEMENTS IN THE CARDS AND MAGNETS OF MARINERS' COMPASSES
Year: 1876

page_text: PROVISIONAL SPECIFICATION left by Edward Samuel Ritchie at the Offico
of the Commissioners of Patents on the 15th June 1876.
EDWARD SAMUEL RITCHIE, of Brookline, Massachusetts, United States of America,
now of No. 8, Southampton Buildings, London. "IMPROVEMENTS IN THE CARDS
AND MAGNETS OF MARINERS' COMPASSES."
The first part of my Invention relates to a compass card composed of a concen-
trated buoyant air vessel, a perforated plate or divided ring, and one or more
magnets and arms, arranged and constructed substantially as herein-after set forth.
The second part of my Invention relates to the magnet or magnets of such liquid
compasses, which magnet in order to distinguish it from others heretofore in use I
term the "Fascicular magnet," it being composed of a series of separate rods or
wires of steel laid parallel or side by side in a pack, and all secured together by any
suitable means, most generally by a closely fitting or water-tight case, such as will
protect them from being oxidated.
The card consists of a perforated disc or a divided ring, a concentric spheroidal or
ball-shaped or concentrated buoyant vessel, and two or any other suitable number
of magnets, and two or any other suitable number of arms. The said vessel is
arranged within and concentric with the perforated disc or ring. The magnets
extend across the ring and through or partly through the buoyant vessel. These
magnets may be of ordinary construction, but I prefer to compose each as aforesaid
of a pack of drawn steel wires laid side by side, or parallel with each other, and
secured together by being arranged and enclosed in a tube, or by other suitable
means.
A
The divided ring is fastened to the magnets and also to two arms extended from
said magnets. Around the buoyant vessel and between it and the divided ring are
openings for the liquid of the compass bowl to flow freely through the card.
lise perforated with holes for the passage of the liquid through it may be substi-
tuted for the annulus. The air vessel has within it a hollow cone open at its lower
end, and provided with the pivot bearing. It is important that the liquid should
be able to pass freely through the card in order to reduce the resistance and enable
the card to maintain its equilibrium or work to the best advantage. The centre of
buoyancy of the air vessel should be a little above the centre of gravity of the card.
In carrying out my Invention I prefer to employ a ring for the reception of the
marks or divisions indicative of the points of the compass, but as herein-before
stated a flat wheel or disc having a series of openings made through it for the free
[Price 2d.]

page_text: passage of the liquid may be substituted for such ring. The ring may be flat or it
may be inclined, so as to have the surface upon which the eye usually looks while
the compass is in use perpendicular or nearly so to the line of sight.
Heretofore in mariners' liquid compass cards the buoyant vessels have generally
been composed of elongated cylindrical tubes placed parallel or radially to each
other. In my present construction or use of a single concentrated buoyant vessel
I diminish the inertia and resistance and otherwise gain advantage, especially in
simplicity and cheapness of construction.