Improvements in Mariners' Compasses.
Year: 1895

page_text: Date of Application, 5th Feb., 1895-Accepted, 23rd Mar., 1895
COMPLETE SPECIFICATION.
Improvements in Mariners' Compasses.
I, JOHN ALBERT HOOPER, of 127 Causeway Street, Boston, in the County of
Suffolk and State of Massachusetts, United States of America, Hotel Proprietor,
do hereby declare the nature of this invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement :-
In
My invention relates to stops for marine compasses. Such stops as hitherto
made lift the card from its point of rest against the glass to hold the same.
practice it is found that this method is very defective, the card often shifting one
or two points while being raised, thus rendering the reading incorrect, so that the
mariner is misled in his calculations. Now, the object of my invention is to over-
come this defect, and to produce a stop for marine compasses which will hold the
card without variation.
The invention relates to two jaws adapted to clasp the underside of the card
spindle, said jaws being operated by a lever compressing an expansion chamber
which raise a tube that operates upon the outer ends of rods carrying the jaws, as
hereinafter fully described and pointed out in the claims.
Referring to the accompanying drawing:
Fig. 1 represents a side view of a marine compass embodying my invention.
Fig. 2 is a vertical section through same.
Fig. 3 is a view of the underside, the bottom plate being removed.
Fig, 4 is a plan or top view with the outer ring, glass and card removed.
Figs. 5 and 6 are detail views.
A, represents the body, or outer casing; B, the bottom plate; C, the glass;
D, the upper ring; E, the packing; F, the pivot post; G, the card; and H, an
expansion chamber; all of which may be of ordinary construction. I, is a cross bar
secured to the lower portion a, of the casing A. J, J, are bent rods formed at
their inner ends with jaws j, to clasp around the lower end g', of the card spindle g;
the said rods are mounted in bearings K, secured to the cross bar I.
L, is a wire spring secured to the cross bar I, by a screw 1, the ends of which
spring rest upon the ends of the jaw rods J, to hold them down, in which position
the jaws, clasp the card spindle y¹, to hold same. Just under the outer ends of
the jaw rods J, is a tube M, that passes through an aperture formed in the cross
bar I, and bottom a; the lower end of the tube or rod M, is attached to a plate
forming an expansion chamber N, said plate being secured around its edges to the
bottom a; on the underside of this expansion chamber N, and opposite the tube M,
is secured a smali wedge-shaped piece of metal n.
P, is a lever fulcrumed on a screw p, secured to the bottom a; the outer end of
this lever projects through an aperture Q, formed in the outer casing, and its end
is bent up as shown; the lever is formed with an enlargement p', the underside of
which is preferably wedge-shaped, to correspond to the shape of the piece n. The
aperture Q, regulates the travel of the lever P, and when pushed on one side, as
shown in full lines in Fig. 3, the jaws j, will clasp the lower end g', of the card
spindle and hold it firmly, and when the lever P, is pushed into the position shown
in dotted lines the two wedge-shaped portions p, n, will be in contact with each
other; thus the bottom of the expansion chamber N, will be slightly depressed in
its centre, and the tube M, will be raised, thus forcing the outer ends of the jaw
rods J, up, which of course imparts a similar inovement to the jaws j, and throw
the jaws j, out of contact with the lower end g' of the card spindle, thus releasing

page_text: the card. The fluid that is forced from the expansion chamber N, is taken up by
the expanding chamber H, in the usual manner.
When in use the lever P, is kept in the position shown in dotted lines in Fig. 3,
so that the card is free to rotate, and when an observation is being taken, the
moment the compass is in the desired position the lever P, is pushed over to the
position shown in full lines, and the jaws, grasp the lower end of the card
spindle and hold it without the slightest variation; thus the mariner is not misled
in his calculations.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. In a compass the combination with the card spindle, of a pair of jaws adapted
to clasp the lower end of the card spindle, and a lever and connections between
said lever and jaws; all operating substantially as and for the purpose set
forth.
2. In a compass the combination of a card spindle, jaws adapted to clasp the
same; a spring, a tube attached to an expansion chamber, a wedge-shaped piece
on the underside of said expansion chamber, and a lever for operating same;
substantially as set forth.
3. In a compass the body A, bottom a, provided with two expansive
chambers N, H, the card G, and spindle g, in combination with a pair of
jaws j,j, a tube attached to the expansive chamber N, a spring L, and a lever P,
for operating the expansive chamber N, and connection between same and the
jaws; substantially as set forth.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.