An Improvement in Ships' Compass Course Correctors.
Year: 1892

page_text: Date of Application, 11th Aug., 1892
Complete Specification Left, 22nd Apr., 1893-Accepted, 17th June, 1893
PROVISIONAL SPECIFICATION.
An Improvement in Ships' Compass Course Correctors.
I, JOHN WILSON GILLIE of The New Quay, North Shields, in the County of
Northumberland, Maker and Adjuster of Ships' Compasses do hereby declare the
nature of this invention to be as follows:-
The object of my invention is an improvement in the construction of the
instruments known as compass course correctors, and particularly of that described
in my Complete Specification numbered 7077 and dated 26th May 1886; in order
that while the deviation may be ascertained with simplicity and facility, the
instrument may also be used for taking compass bearings and measuring horizontal
angles.
In order to obtain this combination of results, two things are necessary, viz.―
1stly. The dial or dumbeard must be capable of being clamped to the sights, so
that the two may revolve together round a common centre spindle, attached to
which there is a pointer or index to represent the direction of the ship's head and
some means of mechanically adding or subtracting the variation.
2ndly. The dial or dumbeard must be capable of being clamped to the ship's
head pointer or index, so as to permit of the sights being revolved independently.
Now the ability to permit of the 1st operation being carried out is one of the
distinguishing features of my instrument alluded to above as hitherto constructed.
While at the same time, with other well known instruments in use at the present
time, the 2nd operation can be performed but not the 1st, and I am ignorant of
any instrument which permits of both operations being easily carried out.
I therefore propose to make the hole in the dial plate, in which the centre
spindle is placed, and which hitherto has been the same size as the hole in the
sight bar, smaller; and to turn a separate bearing on the end of the centre
spindle to carry the dial independently of the sight bar, the latter revolving under-
neath the dial plate and just clearing it, so that when a centre clamping screw
attached to the centre spindle is tightened, it will bind the dial upon its bearing
on the spindle, but will allow of the sight bar revolving freely on its own bearing.
In this way I shall be able to perform the 2nd operation without interfering with
the 1st, for in using the instrument for ascertaining the deviation only or to perform
the 1st operation, I tighten a small binding screw screwed through the sight bar
near the end, the point of which bears against the dial, the friction so set up at the
circumference of the plate overcoming that at the centre caused by the centre
screw, allows of the dial and sight bar being moved round together as before.
In this method of performing the 1st operation I however claim no novelty, it being
already mentioned in my former Patent. My invention being the way in which
with one instrument I make it possible to perform both operations as described
with equal facility.
Dated this 10th day of August 1892.

page_text: COMPLETE SPECIFICATION.
An Improvement in Ships' Compass Course Correctors.
I, JOHN WILSON GILLIE Nautical Instrument Maker of The New Quay,
North Shields in the County of Northumberland 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 :-
The object of my invention is an improvement in the instruments known as
compass course correctors, and particularly of that described in my Specification
numbered 7077 and dated 26th May 1886, so that whilst the deviation of the
compass may be ascertained with simplicity and facility, compass bearings may
be taken and horizontal angles measured. In order to obtain this combination of
results two things are necessary viz.
also
1st. The dial or dumbeard must be capable of being clamped to the sights in
such a way that the two may revolve together round a common centre spindle,
attached to which there is a pointer or index to represent the direction of the
ship's head and some means of mechanically adding or subtracting the variation.
2nd. The dial or dumbeard must be capable of being clamped to the ship's
head pointer or index, so as to permit of the sights being revolved independently.
The first is desirable in order that the deviation on any course may be easily
ascertained. The second is necessary in order that compass bearings may be taken,
for supposing a vessel is steering north by the compass, then it is necessary that
the dial or dumbeard should be clamped with north to the ships head in order that
the sights may be moved round, and bearings taken in the same way, as if the
sights were mounted upon the compass itself. The instrument described in my former
Patent cited above, permits of the first operation being carried out, but does not
permit the second. While at the same time, with other well known instruments in use
at the present time, the second operation is possible but not the first, and I am ignorant
of any instrument which permits of both being easily carried out. Referring to
the figure in the accompanying drawing, which represents a section through a
course corrector made according to the method of my invention, B. B. represents
the centre spindle, to the lower end of which is attached the weight H, by which
the instrument is kept plumb and steady. A collar C. on the upper part of the
spindle B. B. carries studs D. D. into which are screwed two screws which work
in holes in the ring E, which again is supported by two studs or screws which
work in lugs projecting from the cone G, which is arranged to fit a socket on the
top of a binnacle or on other convenient position. The cross bar J. J. carries the
short sight K. and the hinged taller sight L., and is movable round the central
spindle B. B. N. is a pointer which is fitted on a square filed on the spindle, and
when the instrument is in position, is always in a line with the keel of the vessel.
O. is another pointer which moves freely round the spindle B. B., but may be
clamped by the centre binding screw P. at any angle from N., and so permits of an
allowance being made for the magnetic variation. A is a dial divided to degrees
and quarter points, moving round the centre spindle B. B. and capable of being
clamped by the centre clamping screw P. to the pointers N. & O., or by the
binding screw M. to the sight bar J. J.
The method I prefer to adopt to carry out the object of my invention consists,
in turning a separate bearing for the dial or dumbeard A. on the spindle B. B. as
shown at 8, and in making a smaller hole in the dial or dumbeard to fit the said
bearing. The bearing 8, is so made that when the centre clamping screw P. is
tightened, the dial is bound on its bearing, but the sightbar J. J. is free to move.
This enables the second operation to be carried out. To perform the first operation,
the centre clamping screw P. is slightly eased, and the small binding screw M. is
used to clamp the sights to the dial.

page_text: 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.
1st. In compass course correctors, the combination of a dial or dumbeard capable
of being clamped either to the sights (or sight bar) or to the ship's head pointer
or index, with a pointer or index for mechanically adding or subtracting the
variation.
2nd. In compass course correctors the spindle B. B. as herein described and
illustrated in the accompanying drawing.
my improved
3rd. The general arrangement and combination of parts in
compass course corrector, substantially as herein before described and illustrated.
Dated this 20th day of April 1893.
JOHN WILSON GILLIE.