IMPROVEMENTS IN MARINE COMPASSES, AND IN ADJUSTING THE SAME ON BOARD SHIP
Year: 1856

page_text: LETTERS PATENT to William Graham, of Glasgow, in the County of
Lanark, North Britain, Master Mariner, for the Invention of "IMPROVE-
Sealed the 20th May 1856, and dated the 17th March 1856.
PROVISIONAL SPECIFICATION left by the said William Graham at
the Office of the Commissioners of Patents, with his Petition, on the
17th March 1856.
I, WILLIAM GRAHAM, of Glasgow, in the County of Lanark, North Britain,
Master Mariner, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN MARINE COMPASSES, AND IN ADJUSTING THE SAME ON BOARD
SHIP," to be as follows, that is to say :-
This Invention relates, in the first place, to various improved mechanical
applications and arrangements connected. with the mariner's compass, and
intended for the purpose of neutralising or correcting the effects of local
attraction upon the compass needles; and, secondly, this Invention relates to a
system or mode of adjusting the compass on ship board. As regards the
corrective arrangements for the local attraction, this invention, is to a certain
extent based upon or connected with an Invention, for which British Letters
Patent were granted to John Sands, as a communication from William

page_text: Graham, and bearing date on or about the Thirtieth day of November, One
thousand eight hundred and fifty-four.
According to the present Invention, a series of four, six, eight, or other
number of corrective. magnets are disposed round the compass needle or
needles upon a platform or other support, in. such manner that the magnets
shall be at or near the level of the compass card or needles. These corrective
magnets, whatever may be their number, are preferred to be arranged
tangentially to a circle described from the centre of the compass card, or they
may be placed broadside on to the centre, or in positions deviating in some
measure from this arrangement, and laid either horizontally or at an angle
with the horizon. The corrective magnets are capable of minute adjustment
to suit the corrective action required either by screws or other contrivance.
The centre point carrying the compass card is adjustable vertically in the bowl
of the compass, so as to enable the shipmaster to set the card and its needle
at any desired height, so as to rectify the beeling deviation when such exists;
or, instead of thus shifting the centre point, the gimbals or points of suspension
may be fitted with vertical adjusting apparatus to gain the same end. The
operation of adjusting the compass on board ship is performed in this way:-
When the compass is placed on deck and duly fixed fore and aft, corrective
magnets are disposed, after the manner already described, one on each side of
the compass card. The ship's head may then, for example, be turned to the
east, and the fore and half corrective magnets adjusted so as to cause the
compass needles to point correctly; then the ship's head is turned, say, to the
north-east, when the compass may be found to deviate more or less from the
truth. To correct this error, two additional magnets are put down, one on
each side of the compass card, to act in concert with the first pair. These
latter magnets are disposed east and west, or so as to occupy the precise
positions with relation to the earth which the first pair occupied before shifting
the ship's head to north-east, and they are now adjusted to bring the compass
needle correct in the position to which the ship's head has been turned, that is
the north-east. Having done this, the last adjusted pair of magnets is removed,
and then placed on a line running from north to south. Adjustment is now
secured by the aid of a third pair of magnets, which are to be placed in the
positions from which the second pair was removed, the ship's head still
remaining in the north-east. position. If the ship's head is now turned to the
south and any error of the needle appears, a fourth pair of magnets is placed
in an east and west line; should there be no deviation of the needle when the
ship's head points to the south, then the fourth pair of magnets will be
unnecessary. It is intended indeed that six corrective magnets only should be

page_text: employed in this system of adjustment, but four or more may be used at
pleasure.
Although certain points have herein been selected as those to which the
ship's head might be turned in effecting the compass adjustment, it must be
understood that such have been selected merely for the sake of illustration,
and that it is not intended to limit the adjustment to the points before named,
as it will be obvious to the practical mariner that any other points may be
taken to carry out the herein-before described mode of adjustment. In using
corrective magnets disposed more or less after the manner already specified
under the Patent granted to John Sands, as herein-before referred to, each
diametrically disposed pair of magnets need not be in lines fore-and-aft and
athwart ship, but may be set at any other points; and instead of disposing
these corrective magnets either radially or tangentially, as herein-before
described, two magnets may be combined to secure both directions in each
case, that is to say, one magnet may be set radially and another one above or
under it in a tangential or transverse direction.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Graham in the Great Seal Patent Office on the
17th September 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
GRABAM, of Glasgow, in the County of Lanark, North Britain, Master
Mariner, send greeting.
WHEREAS. Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Seventeenth day of March, in the year of our
Lord One thousand eight hundred and fifty-six, in the nineteenth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said William Graham, Her special license that I, the said
William Graham, my executors, administrators, and assigns, or such others
as I, the said William Graham, my executors, administrators, or 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 MARINE COMPASSES, AND IN ADJUSTING THE SAME ON BOARD
SHIP," upon the condition (amongst others) that 1, the said William Graham,

page_text: 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 William Graham, do hereby declare
the nature of my 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 in writing, reference being had to the accompanying Drawings, and
to the letters and figures marked thereon, that is to say:-
My said Invention relates, in the first place, to various improved mechanical
applications and arrangements connected with the mariner's compass, ..and
intended for the purpose of neutralising, or correcting the effects. of local
attraction upon the compass needle or needles; and, secondly, this Invention
relates to a system or mode of adjusting: the compass on ship board. As
regards the corrective arrangements for the local attraction, this Invention is
to a certain extent based upon or connected with an invention for which British
Letters Patent were granted to John Sands, as, a communication from William
Graham, and bearing date on or about the Thirtieth day of November, One
thousand eight hundred and fifty-four. According to the present. Invention, a
series of two, three, four, five, six, seven, eight, or any other number of correc-
tive magnets as may be found necessary, are disposed round the compass needle
or needles upon a platform or other support, in such manner that the magnets
shall be at or near the level of the compass card or needle. These corrective
magnets whatever may be their number, are preferred to be arranged radially
to a circle described from the centre of the compass card, or they may be placed
broadside on to the centre, or in positions deviating in some measure from
this arrangement, and laid either horizontally or at an angle with the horizon.
These corrective magnets are capable of minute adjustment to suit the
corrective action required either by screws or other contrivance. The centre
point carrying the compass card is adjustable vertically in the
compass, so as to enable the shipmaster to set the card and its needle at any
desired height, so as to rectify the heeling deviation when any exits; or, instead
of thus shifting the centre point, the gimbals or points of suspension may be
fitted with vertical adjusting apparatus to gain tlie same end.
bowl of the
The operation of adjusting the compass on board ship is performed in this
way When the compass is placed on deck and properly fixed fore and aft,
'corrective magnets are disposed, after the manner already described, one on
each side of the compass card. The ship's head, may then, for example, be

page_text: turned to the east; and the fore-and-aft corrective magnets be adjusted.so as to
cause the compass needles to point correctly; then the ship's head is turned;
say, to the north-east, when the compass may be found to deviate more or less
from the truth. To correct this error, two additional magnets are put down,
one on each side of the compass card, to act in concert, with the first: pair.
These latter magnets are disposed east and west, or so as to occupy the precise
positions-with-relation to the earth which the first pair. occupied before shifting
tlie ship's head to north-east, and they are now adjusted to bring the compass
needle correct in the position to which the ship's head has been turned, that is, to
the north-east. Having done this, the last adjusted pair of magnets is removed,
and then placed on a line running from north to south, and, at the same
distance from the centre of the card as they occupied before shifting them.
Adjustment is now secured by the aid of a third pair of magnets, which are to
be placed in the positions from which the second pair was removed, the ship's
head still remaining in the north-east position; or, instead of shifting the
second pair of magnets, the ship's head may be moved to the north or south,
and the third pair of magnets applied at right angles to the second pair; or,
after adjustment is, made by the first part, the ship's head may be turned to
the north or south, and, the error corrected by compensation for, half the error
of each pair of magnets. It is intended indeed that five or six corrective
magnets only should be employed in this system, of adjustment,. but four or
more may be used at pleasure.
Although certain points have herein been selected as those to which the ship's
head might be turned in effecting the compass adjustment, it must be under-
stood that such have been selected merely for the sake of illustration, and that
it is not intended to limit the adjustment to the points named, as it will be
obvious to the practical mariner that, any other points may be taken to carry
out the herein-before described mode of adjustment. In using corrective mag-
nets disposed more or less after the manner already specified under the Patent
granted to John Sands, as herein-before referred to, each diametrically disposed
pair of magnets need not be in lines fore-and-aft and athwart ship, but may be
set at any other points. And instead of disposing these corrective magnets
either radially or tangentially, as herein-before described, two magnets may be
combined to secure both directions in each case, that is to say, one magnet
may be set radially and another one above or under it in a tangential or trans-
verse direction.
And in order that my said Invention, may be properly understood, I have
hereunto appended and shall now proceed, to describe a Sheet of explanatory
Drawings, relating thereto.

page_text: Figure 1 on the Sheet of Drawings is an elevation of a compass binnacle as
arranged for carrying out my said Invention under one modification thereof;
Figure 2 is a vertical, section through the binnacle, the compass bowl, and
gimbal rings; Figure 3 is a plan of the top of the binnacle, showing the
compass and magnets in position; and Figure 4 is a vertical section of the
compass bowl and card as drawn to an enlarged scale; the compass card and
bowl may be constructed according to any of the systems in use; in the
Drawings, however, I have represented the arrangement which I prefer to use.
The bowl consists of a brass cylinder A, having glass ends B, to the lowermost
of which last is secured a pedestal C, for carrying the compass card D. This
card D is suspended by jointed links. E to a pivot piece F, which rests in a
step or recess in a supporting piece of metal set on a piece of vulcanized
caoutchouc in the top of the pedestal C. This pedestal C is hollow to allow of
the movement of a weight attached to the piece which supports the pivot or
centre point F. With these arrangements any oscillation or vibration of the
card is entirely or almost entirely prevented. It is preferred to use two
magnetic needles G, which are attached to the under side of the card D, so as
to be parallel to each other. The bowl A is primarily supported by an india-
rubber ring H, which rests on a flange on the ring I, pins J being attached to
the bowl, and working in a slot in the ring I, so as to prevent any shifting or
sliding of the bowl. Or, again, a still better mode of supporting the compass
bowl A, and of connecting it to the gimbal ring I, is by means of three or
more adjustable chains, cords, links, or springs, as indicated by dotted lines at
a in Figure 4. In this case the india-rubber ring H is omitted, as also the
ledge or ring upon the outside of the bowl, and resting upon the ring H.
These suspensory links, chains, cords, or springs a may be attached by hooks
or otherwise to the bowl and to the ring I, being made capable of adjustment
as to length by means of a screw or otherwise, so that the bowl may be made
perfectly level. The ring I is supported by pivots, connecting it to the gimbal
ring K. The centres of the gimbal ring K are supported in sockets L capable.
of adjustment vertically in the binnacle M. These sockets L slide against a
brass plate N, attached to the inner vertical sides of the binnacle, and are
guided by two vertical guide wires passing through them. Vertical screw
spindles O fitted into the plates N serve for adjusting the sockets L, being
tapped through them as through nuts. Upon the platform P of the binnacle.
are placed brass cases Q to receive the corrective magnets, of which one is
shown uncovered at R. These magnets are arranged to be adjusted to or
from the compass in their boxes by means of screw spindles, as at S, the ends
of these spindles being squared to receive a button key T. Four magnets are

page_text: represented as arranged round the compass in Figure 3 in radial positions, but
the positions for four additional magnets are indicated by dotted lines at U
and V. At V the magnet is indicated as placed broadside on the compass, or
in a position tangential to a circle described from the centre of the compass.
In Figure 1 is shown the usual brass and glazed cover W, for protecting the
compass from the weather, this cover being provided with the usual lamps X
for night use. Instead of arranging the gimbals as detailed in the Sheet of
Drawings hereunto appended, that is to say, within the area comprehended by
the corrective magnets, the gimbals may be constructed so as to be external to
the corrective magnets, the compass bowl itself being a fixture. This is
especially desirable when the corrective magnets are disposed vertically, or not
in the horizontal line.
Having now described and particularly ascertainèd the nature of my said
Invention, and the manner in which the same is or may be used or carried into
effect, I may observe, in conclusion, that I do not confine or restrict myself to
the precise details or arrangements which I have had occasion to describe or
refer to, as many variations may be made therefrom without deviating from
the principles or main features of my Invention; but what I consider to be
novel and original, and therefore claim as the Invention secured to me by the
herein-before in part recited Letters Patent, is,-
First, the general arrangement of marine compasses, and the adjustment of
the same on shipboard, as herein-before described.
Second, the system or mode of neutralising or correcting the local attraction
affecting the action of marine compasses on shipboard, by disposing corrective
magnets around the compass needle, as herein-before described.
In witness whereof, I, the said William Graham, have hereunto set my
hand and seal, this Sixteenth day of September, One thousand eight
hundred and fifty-six.
WILLIAM GRAHAM. (L.S.)