IMPROVEMENTS IN ADJUSTING COMPASSES ON BOARD SHIPS OR VESSELS
Year: 1854

page_text: LETTERS PATENT to John Gray, of Strand Street, Liverpool, for the
"
Invention of IMPROVEMENTS IN ADJUSTING COMPASSES ON BOARD SHIPS OR
VESSELS."
Sealed the 8th May 1855, and dated the 28th December 1854.
PROVISIONAL SPECIFICATION left by the said John Gray at the Office
of the Commissioners of Patents, with his Petition, on the 28th December
1854.
I, JOHN GRAY, of Strand Street, Liverpool, do hereby declare the nature of
the Invention for "IMPROVEMENTS IN ADJUSTING COMPASSES ON BOARD SHIPS OR
VESSELS" to be as follows:-
Heretofore the compasses in iron ships have been adjusted by permanent
magnets, fixed in such positions as to cause the compass to give correct indi-
cations at the time of adjustment, but should any of the magnetic conditions of
the ship afterwards change, the indications are no longer correct. Now, my
Invention consists in arranging the correcting magnets so that they may
be moved in any direction, by screws, or rack and pinion, or otherwise,
so that when any deviation of the compass is detected, it may at once be
remedied.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Gray in the Great Seal Patent Office on the
28th June 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
GRAY, of Strand Street, Liverpool, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-eighth day of December, in the year of our
Lord One thousand eight hundred and fifty-four, in the eighteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said John Gray, Her special licence that I, the said John Gray, my executors,
administrators, and assigns, or such others as I, the said John Gray, my
executors, administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend, within the
United Kingdom of Great Britain and Ireland, the Channel Islands, and Isle
of Man, an Invention for "IMPROVEMENTS IN ADJUSTING COMPASSES ON BOARD
SHIPS OR VESSELS," upon the condition (amongst others) that I, the said John
Gray, by an instrument in writing under my hand and seal, should particularly
describe and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately after
the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Gray, do hereby declare the
nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof (that is to say) :-
÷-
Heretofore the compasses in iron ships have been adjusted by permanent
magnets, fixed in such positions as to cause the compass to give correct
indications at the time of adjustment; but should any of the magnetic conditions
of the ship afterwards change, the indications are no longer correct. Now,
my Invention consists in arranging the correcting magnets so that they
may be moved in any direction, by screws, or rack and pinion, or otherwise,
so that when any deviation of the compass is detected, it may at once be
remedied.
Having thus stated the nature of my said Invention, I will proceed to
describe the manner of performing the same.
Heretofore it has been usual to fix the correcting magnets on board ship

page_text: when the desired adjustment of the compass has been obtained, so that should
the magnetic conditions of the ship be changed during a voyage, there has.
heretofore been no ready means of adjusting or of varying the positions of the
correcting magnets. It has, however, lately been proposed to have four or
more correcting magnets applied radially to a compass, and in the same plain
with the compass card, in such manner that the correcting magnets may be
moved by screws in radial directions, and in the lines of the longer axes of the
correcting magnets, to and from the compass card. Now, according to my
Invention I cause the correcting magnets to be so arranged in respect to the
compass, that part of them shall be placed in a line, or parallel with the keel
of the ship, and part shall be placed transversely across the keel of the ship or
vessel, and at right angles thereto. These correcting magnets are arranged
and capable of movement or adjustment to and from the compass in lines
transverse of the longer axis of the correcting magnets, and they are not
moveable in the directions of their longer axes. And I also apply an adjust-
ing magnet vertically below the point or axis of the compass card, and capable
of adjustment upwards and downwards in a line with the centre of the pin or
axis of the compass card. By these means the correcting magnets may be
moved in any or every direction, by screws, or racks and pinions, or otherwise.
The means of thus applying adjustable correcting magnets may be varied, but
I prefer that arrangement which is shewn at Figures 1 and 2, which respec-
tively show a vertical and horizontal section of the pinnacle of a ship having
the adjusting and correcting magnets applied thereto; but they may be
similarly applied to the deck or other part of the ship, so long as the correcting
magnets are made adjustable in the direction shewn. I usually employ two
sets of three magnets, but single ones of greater power, or other numbers than
three, may be used.
In the arrangement shewn there is one set of three magnets on one side of
the binnacle, and another set of three magnets in the front of the binnacle, so
that those in front will be across the keel of the ship, and at right angles
thereto, whilst the magnets at the side of the binnacle are in a line parallel
with the keel of the ship. a is a screw, which passes through a screw nut
fixed to the plate b, to which the three correcting magnets c, c, in front of the
binnacle are fixed, parallel to each other, by the plate d and screws, as shewn ;
hence, by turning the screw a up or down, the magnets c will be brought
nearer to or further from the compass, which is placed in the recess or box e
at the top of the binnacle. In like manner are the correcting magnets f,f, at
the side of the binnacle set and moved by the screw g; or, in place of the
screws, racks and pinions may be used. h is a vertical magnet in the brass

page_text: bar i, which is moved up and down by a pinion and rack, and set to any
position by the screw j.
In adjusting a compass on board ship, it is to be placed in its position on the
binnacle, the adjusting magnets c, c, f,f, and h being first removed. The ship
is to be brought due north and south and the variation of the compass
observed. The adjusting magnets c, c, are then fixed in their frame, and to be
adjusted up or down till the variation of the compass is corrected; then the
ship is to be brought due west and east, and the correcting magnets f, f, are
to be introduced and moved up or down till the variation in the compass is
adjusted; the vessel is then to be heeled over, and the vertical magnet h
introduced, and adjusted up or down till the variation of the compass has been
adjusted.
Having thus described the nature of my said Invention, and the manner of
performing the same, I would have it understood that what I claim is, the
arranging correcting magnets with means of adjustment, by screw, by racks
and pinions, or by other means, so that they may be moved to and from the
compass in the directions herein described.
In witness whereof, I, the said John Gray, have hereunto set my hand
and seal, this Twenty-seventh day of June, in the year of our Lord One
thousand eight hundred and fifty-five.
Witness,
JNO. COOK,
12, Cursitor Street, Chancery Lane.
JOHN GRAY. (L.S.)