IMPROVEMENTS IN AND RELATING TO THE MARINER'S COMPASS, AND IN APPLIANCES FOR ADJUSTING AND CORRECTING TOE PROVISIONAL SPECIFICATION
Year: 1880

page_text: LETTERS PATENT to Duncan McGregor, of Liverpool, in the County of
Lancaster, Fellow of the Royal Geographical Society, and Nautical Instrument
Maker for an Invention of "IMPROVEMENTS IN AND RELATING TO THE
MARINER'S COMPASS, AND IN APPLIANCES FOR ADJUSTING AND CORRECTING
TOE
PROVISIONAL SPECIFICATION left by the said Duncan McGregor at the
Office of the Commissioners of Patents on the 12th June 1880.
DUNCAN MCGREGOR, of Liverpool, in the County of Lancaster, Fellow of the
Royal Geographical Society, and Nautical Instrument Maker. "IMPROVEMENTS IN
AND RELATING TO THE MARINER'S COMPASS, AND IN APPLIANCES FOR ADJUSTING
AND CORRECTING THE SAME."
My Invention has for its object,-
First. To simplify and render more reliable the action of the mariner's compass,
and to as far as possible remove or compensate for the vibration such as that caused
by the action of the engines of steamers, or the motion of a vessel in a seaway, or
other causes.
Second. To provide a simple and efficient means for adjusting the mariner's
compass and correcting the errors of same in composite, steel, or iron vessels.
Third. To provide a simple and improved method of lighting binnacles at night
by which the compass card may be clearly seen.
The compass consists,―
First. Of two basins or bowls having weighted bottoms, one of which floats
within the other, and is supplied with any convenient form of guides and top
springs to keep it, the inner bowl, in a central position floating in the outer bowl.
A ring of copper may or may not be fitted inside the inner bowl as occasion
requires, and the centre pivot of the bowl is of fine tempered steel with brass
mountings, and may or may not be fitted in a tube with any elastic material to
compensate for vertical vibration on shipboard. The bowls can be arranged with
glass bottoms, so as to be transparent to let light through from underneath. By
another method the jewelled cap of card may be fixed to the centre tube below
and the pivot may be fixed in the cap above. A graduated circle, or part of one,

page_text: with an index pointer may be attached to the compass or binnacle to show the
heel of the vessel.
Second. The compass card, which may be made of any suitable size, is composed
of mica or other suitable light material, upon which may be painted, printed,
photographed, engraved, or otherwise delineated the usual points, half and quarter
points, and also degrees if required. By another method an impression of the
compass card printed upon paper may be used along with the mica, or an
impression of the compass card upon any light woven material, such as fine cloth
or silk, may be stretched on a light metal frame, or frame composed of cane, whale-
bone, or any other suitable material, and used instead. The jewelled cap in the
centre may be fitted on a light bridge of brass or other metal, or may be fitted in
any other suitable material, such as cane or whalebone, or it may be fitted to a
collar in the card itself. The directive power of the card is supplied by one or
more magnets composed of flat thin steel of equal or varying lengths, similar to the
steel used for chronometer or other horological instrument springs. These springs
form the direction magnets or needles, and are fitted to the underside of the card
by means of light suitable metal springs, or springs of other material, such as india
rubber, cane, or whalebone may be used, but by preference I use light brass; or
these direction magnets may be attached to the card rigidly close to it or at some
distance from it. When more than two direction magnets or needles are used I
by preference arrange them upou a frame in sockets of cork or other light suitable
material, and at some little distance apart from each other; but they may also be
placed near each other, provided any light non conducting substance is placed
between them to prevent metallic contact. Light steel bars, square or of other
shapes, may also be used.
Third. The binnacle bowl is provided with a strong ring, of brass or other
suitable material, suspended by india rubber or other suitable elastic material.
The ring is provided with ears into which the journals of the gimbal ring of the
compass fits, and the form of these journals may be varied as found necessary.
Fourth. The binnacle upon which the compass and bowl is mounted is by
preference cylindrical in form, although a square or other suitable shape may be
used, and may be composed wholly of brass or other suitable metal or alloy, or wood,
or a combination of wood and metal, and is provided with a suitable opening door,
by means of which access can be had to the interior for adjusting the magnets used
for correcting the errors of the compass. By another arrangement the binnacle
bowl with other necessary fittings may be fitted upon one or more supporting
metal brackets, or upon supports of wood, or other suitable material for use in
wheel houses or where space is limited.
The means for adjusting the compass and correcting the errors thereof consist,-
First. Of arranging vertically inside the binnacle two or more pairs of straps, of
brass, wood, or other suitable material provided with holes, and to which the com-
pensating magnets may be fitted with suitable thumbscrews, pins, or notches, as
found necessary. These magnets can be arranged as fore and aft and thwart ship
magnets, as desired, and can be arranged both fore and aft and both port and
starboard, or in any other way found necessary.
Second. For correcting the heeling error a central case is provided in the
binnacle, which contains if required a vertical magnet provided with a cross pin, so
that the magnet may be adjusted vertically in its relation to the compass by
placing the cross pin in any of a series of notches formed in the containing case.
Third. The quadrantal error is corrected by means of one or more pieces or
blocks of soft iron, which may be used singly or together, and which are fitted into
boxes, cases, or frames, which are placed one at each side of the binnacle bowl and
made adjustable, so that they may be set at any required angle. Soft iron chain
may also be used when suitable.
Fourth. The compass bezil which carries the glass may also have an arrangement
or apparatus for taking observations of celestial objects, or for taking cross
bearings, or other purposes. A reflector, rigid or moveable, and with or without

page_text: prism, sighted with one or more sight vanes, with shades and telescope being used
for this purpose. The telescope may be omitted. The binnacle top or cover may
be made of various forms, and is composed of brass, copper, or other suitable metal
or alloy, or partly brass and partly copper; the taper, pyramid, or dome shapes are
to be preferred.
One lamp adapted for burning mineral oil, such as parrafin, and arranged to
throw light by reflection or otherwise on the lubber's point of the compass, may be
used instead of the ordinary oil lamps in general use at the present time. By
another arrangement two lamps may be used at the sides of the binnacle or cover,
or one lamp may be fitted in the upper part of the binnacle cover to throw the
light down upon the compass, or in the lower portion of the binnacle to throw the
light up from below. An exit for heated air is provided, and an arrangement
also made for proper ventilation. These lamps may be provided with one or
more wicks.

page_text: usual points, half and quarter points, and also degrees, if required. In the science
of magnetism as applied to navigation the northern polarity is termed red polarity,
and southern polarity is known as blue polarity. According to my Invention,
to distinguish this I colour the letters on the northern half of the card red and on
the southern half blue. By another method of card construction an impression of
the compass card printed upon paper may be used along with the mica, or an
impression of the compass card upon any light woven material, such as fine cloth or
silk, may be stretched on a light metal frame or frame composed of card, whalebone,
or any other suitable material. The jewelled cap F in the centre of the card may
be fitted on a light bridge G of brass or other metal, or the cap may be fitted in
any other suitable material, such as cane or whalebone, or it may be fitted to a
collar in the card itself. The directive power of the card is supplied by the
magnets H, which are composed of one or more flat thin steel bars of equal or varying
lengths, similar to the steel used for chronometer springs but of a harder temper.
In the Drawings the magnets H are shown composed of two sets of three such
bars, which compose and form the direction magnets or needles of the card E.
These magnets or needles H, H, are, according to my Invention, fitted to the underside
of the card E by means of the springs J, which are composed of light brass or
other inetal, cane, whalebone, or other suitable material. The ends of the springs J
are attached to the card E by the spiral springs K, composed of fine gold or other
wire. The magnets or needles H are attached to the springs J in the form of a
frame, the bars being separated by ferrules of cork or wood, so as to keep them
apart from each other. The bars may also be placed nearer each other, provided that
any light non conducting substance is placed between thein to prevent metallic
contact. M, M, M, M, are vanes of mica or other suitable light material, which
I sometimes place underneath the card E, as shown at Figures 2 and 3, to arrest
excessive sensitiveness of the card, but these vanes will only be used under
exceptional circumstances.
Third (reference to Figures 1, 4, and 5). The binnacle bowl N is according to my
Invention provided with a strong ring of brass or other suitable material P, which
ring P is suspended within and from the bowl N by means of india rubber or other
elastic hangers Q. The ring P is provided with lugs or ears R, into which the
journals of the gimbal ring S of the compass fit. The form of these journals may
be varied as found necessary.
Fourth (reference to Figures 6 and 7). The binnacle stand T upon which the
compass and bowl is mounted is, by preference, cylindrical in form, although a square
or other suitable shape may be used. The stand may be composed wholly of brass or
other suitable metal or alloy, or wood, or a combination of wood and metal, and is
provided with a suitable opening door T¹ by which access can be had to the
interior, for adjusting the magnets, hereafter referred to, used for correcting the
errors of the compass. By another arrangement the binnacle bowl N with other
necessary fittings may be fitted upon one or more supporting metal brackets, or
upon supports of wood or other suitable material, for use in wheel houses or where
space is limited.
The means for adjusting the compass and correcting the errors thereof, according
to my Invention, consist,―
First (reference to Figures 6 and 7). Of arranging vertically inside the binnacle T
two or more straps U of brass, wood, or other suitable material, provided with holes,
to which straps compensating magnets are fitted and attached by the thumb screws
W or by the notches. The magnets V can be arranged as fore and aft and athwart
ship magnets, as desired, and can be arranged both fore and aft and both port and
starboard, or in any other way found necessary. The magnets V slide on the straps
or bars U, and are fixed at any required elevation by the thumb screws W.
Second. For correcting the heeling error a central magnet X is provided, which
central magnet X has vertical movement on the strap or bar Y and is held by the
thumb screw Z, and can be adjusted vertically in its relation to the compass.
Third. Quadrantal error is corrected by means of one or more pieces or blocks of

page_text: soft iron, which may be used singly or together, and which are fitted into the
boxes, cases, or frames a, Figures 4 and 5, which are placed one at each side of the
binnacle bowl N and made adjustable so that they may be set at any required
angle soft iron chain may also be used when suitable.
The binnacle top or cover b may be made of various forms, and is composed of
brass, copper, or other suitable metal or alloy, or partly brass and partly copper.
The taper, pyramid, or dome shapes are to be preferred.
One lamp d for burning mineral oil, such as parrafine (see Figure 1), may be used
with a proper parrafine burner. This lamp is arranged to throw light or reflection
on the lubber's point of the compass, and may be used instead of the ordinary oil
lamps in general use at the present time.
By another arrangement two lamps may be used at the sides of the binnacle
cover; or one lamp & may be fitted in the upper part of the binnacle cover to
throw the light down on the compass; or the lamp can be fixed in the lower
portion of the binnacle to throw the light up from below and illuminate a
transparent compass and bowl.
Having now described and ascertained the nature, object, and purposes of this
my Invention, and shown how the same may be put into practical operation, I
would have it understood that I do not claim as my Invention those parts herein
described which are to be found in compasses at present in use, as in the description
of a complete apparatus it has been necessary for me to use terms and describe
parts which, separately, do not come under my Invention. I would also have it
understood that those parts which are claimed as my Invention may be used with
other bowls, binnacles, and combinations than that shown.
Under the first part I claim,-
First. A compass card, such as E, in which the directive power of the card is
supplied by one or more magnets composed of flat thin steel suspended by springs
underneath the card, substantially as herein described and shown in Figures 1, 2,
and 3 of the Drawings hereto annexed.
Second. The arrangement and construction of compass card and direction
magnets or needles, substantially as herein described and shown in Figures 1, 2,
and 3 of the Drawings hereto annexed.
Under the second part I claim,-
The arrangement for adjusting in the binnacle the magnets used for correcting
the errors of my compass, substantially as herein described and shown at Figures 6
and 7 of the Drawings hereto annexed.
Lastly, I claim,-
The general construction and arrangement of the mariner's compass, as herein
described and shown in the Drawings hereto annexed.
In witness whereof, I, the said Duncan McGregor, have hereunto set my hand
and seal, this Fourth day of December, in the year of our Lord One
thousand eight hundred and eighty.
DUNCAN
(L.S.) MGREGOR.