AN; IMPROVED MAGNETIC BINNACLE FOR COUNTERACTING THE EFFECTS OF LOCAL ATTRACTION ON SHIPS' COMPASSES
Year: 1872

page_text: LETTERS PATENT to John Low, of Boston, Massachusetts, United
States of America, now of No. 8, Southampton Buildings, London,
Branch Pilot, for the Invention of "AN; IMPROVED MAGNETIC BINNACLE
COMPLETE SPECIFICATION filed by the said John Low at the Office.
of the Commissioners of Patents, with his Petition and Declaration,.
on the 4th January 1872, pursuant to the 9th Section of the Patent
Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN Low,
of Boston, Massachusetts, United States of America, now of No. 8,
Southampton Buildings, London, send greeting..
WHEREAS I am in possession of an Invention for "AN IMPROVED
MAGNETIC BINNACLE FOR COUNTERACTING THE EFFECTS OF LOCAL ATTRACTION ON
SHIPS' COMPASSES," and have petitioned Her Majesty to grant unto me, my
executors, administrators, and assigns, Her Royal Letters Patent for
the same, and have made solemn Declaration that I am the true and
first Inventor thereof.

page_text: NOW KNOW YE, that 1, the said Jonn Low, do nereby declare
that the following Complete Specification, under my hand and seal,
fully describes and ascertains the nature of the said Invention, and in
what manner the same is to be performed, in and by the following
statement, reference being had to the accompanying Drawing forming a
part of this Specification :—
The object of my Invention is the production of a binnacle for iron
ships or vessels, whereby the disturbance of the compasses in such
vessels by local attraction is effectually counteracted.
For this purpose
I construct the binnacle of the proper size and shape to receive two
compasses not less than three feet apart from centre to centre. The
binnacle must also be so constructed and supported that the compasses
will stand about four feet or a little more from the deck, and it may
be
made of wood, brass, or other suitable material, and of any required shape
or style. The compasses are of the ordinary construction, and are
supported by gimbals in the usual manner within the binnacle, or in
boxes or cases attached to or forming part of the same.
In the central
part of the binnacle between the two compasses is an adjustable
platform whereon I place a magnet, which when properly adjusted
between the compasses will counteract the local attractions, whereby the
said compasses would otherwise be rendered inaccurate and unreliable.
The manner of effecting the adjustment of the platform and magnet
is hercin-after fully explained. The binnacle is to be placed centrally
between the sides of the ship, and in such a position that one compass
will be exactly fore and aft of the vessel; or, in other words, so that a line
drawn through the centre of both compasses coincides with a line drawn
centrally from end to end of the ship's deck; and great care must be
taken that the centres of the compasses and magnet do not deviato
laterally from this line. The local attraction will be sometimes forward
and sometimes aft of the binnacle. Its direction will be indicated by
the compasses as soon as the binnacle. is properly placed in the ship.
The magnet must be so placed on the platform that its south pole lies
towards the end of the ship from which this local attraction is found
to proceed. In adjusting the apparatus the ships' head should be laid on
a six, seven, or eight point course. Then the magnet is adjusted
endwise and vertically between the two compasses till they are found to
agree with a compass on shore. The magnet is then made fast in the
binnacle, which if the adjustment has been made in a north latitude may

page_text: then be safely relied upon throughout any voyage in such latitude.
If the vessel has to sail in a south latitude the magnet will have to be
reversed endwise and readjusted. The great advantage of having two
compasses with a magnet between them is, that while the two compasses
agree or coincide with each other they may be safely relied on, for should
there be any fault in the magnet or other derangement of the apparatus
the compasses will no longer coincide, and therefore will at once indicato
the necessity for further attention.
Figure 1 is a front elevation of my unproved Donacie; Figure z JS
partly a plan and partly a horizontal section on the line x, x, Figure 1;
Figure 3 is partly an elevation and partly a vertical section on the line
y, y, Figure 2. Like letters indicate the same parts throughout the
Drawing.
a is a table or stand of wood or other suitable material, whereon the
binnacle is supported at the proper height above deck. c, c, arc
boxes or cases for containing the compasses d; e is the adjustable plat-
form, and f is the magnet placed thereon between the two compasses.
The platforme has at its ends projections e¹ which are fitted to slide up
and down in the guides g which slide in and are secured to flanges a¹ in
the binnacle. 1, h, arc tic bars placed at the top and bottom of the said
guides to keep them parallel. i, i, arc pulleys at the top of the guides
Over these pulleys are passed the cords ; which are attached by one end
to the platform e, and by the other end to the counterbalance weights k.
These weights should exactly balance the platforme and magnet f so
that its adjustment may be casily effected. When the correct position
of the said platform has been found it is necessary to secure it therein,
and for this purpose I employ the screws which are passed through
the lugs e formed or fixed on the under side of the platform. These
screws can be made to bind tightly against the guides 9, and will then
hold the platform immoveably. And when any further adjustment
is required the said platform is released by simply turning the screws.
The required lateral or endwise adjustment of the magnet between the
compasses is effected by moving it on the platform, and when properly
adjusted the said magnet is secured by the screws m. ,, is the
horizontal centre line of the ship, with which the centres of the
compasses and magnet must coincide, as shewn in Figure 2. I prefer

page_text: that the magnet should be enclosed in a copper case. The binnacle
is provided with doors a³ on one side, and with other doors a³ at the top.
These doors permit ready access to the interior of the binnacle for
adjusting the platform and magnet, and removing or replacing the
same or any other portions of the apparatus. When the platform e has
been adjusted and secured by the screws to the upright guides g, the
cords and suspended weights may be removed until again required
for regulating and adjusting the magnet f. The compasses are of the
ordinary kind used by sea-going vessels. They are provided with
lanterns a attached to the boxes c as shown, and the said boxes have
covers c¹ with the usual sight apertures.
Having thus fully described my said Invention and shown how the same
may be conveniently and advantageously carried into practice I claim,―
First. A ship's binnacle with two compasses and an adjustable magnet
arranged between them as herein set forth for the purpose specified.
Second. Constructing the said binnacle with an adjustable platform
for carrying the said magnet as herein set forth.
In witness whereof, I, the said John Low, have hercunto set my
hand and seal, this Third day of January, in the year of our
Lord One thousand eight hundred and seventy-two.
Witness,
W. ROB. LAKE.
JOHN LOW. (L.S.)