IMPROVEMENTS IN THE MARINERS COMPASS
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
FRANCIS MONTGOMERY MOORE, 102 High St. Belfast & 23 Eden Quay,
Dublin, Chronometer Maker; Watch Maker & Optician, do hereby declare the
nature of my invention for THE IMPROVEMENTS IN THE MARINERS COMPASS to
be as follows:-
The use of tubular aluminium in the construction of the card frame.
The suspension of the needles exclusively from the circumference of the frame.
The use of ebonite for the cap, to hold the stone, or center.

page_text: I, FRANCIS MONTGOMERY MOORE of 102 High Street Belfast and 23 Eden Quay,
Dublin, Chronometer Maker, Watch Maker and Optician do hereby declare the
nature of said invention for "IMPROVEMENTS IN THE MARINERS COMPASS" and in
what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
According to this invention I construct a light and sufficiently strong compass
card with low centre of gravity and having its frame proper carrying the paper
card composed of tubular 'aluminium, the needles being placed some distance below
the level of the card proper, arranged in two systems one on each side of the centre,
and by preference vertically above each other, being held in light aluminium frames
or brackets and suspended by thin aluminium strips bands or tubular wires from
the aforesaid card frame proper from points near the circumference. The central
cap which holds the stone or centre" I make of ebonite.
Figure 1 of the accompanying drawings is a sectional elevation Figure 2 a
sectional elevation at right angles to. the previous figure and Figure 3 a plan of
a card, constructed according to this invention.. Figures 4, 5, 6 and, 7 show
modifications of parts of same.
The card proper A Figures 1, 2 and 3 is an ordinary annular paper one which is
lapped round the circumferential tubular rim B. The lip of the paper may be
fastened (though not necessarily so) to the underside, of the paper... The paper will
then have no adhesion to the rim B but being free will permit..the radial bars C
and rim B to be acted on by temperature without being caused to be distorted.
The lip is strengthened underneath by the ring A¹ of thin paper, fastened thereto
as shown. The paper card also rests on the radial bars C which carry the central
ebonite cáp D which is furnished with the usual stone for the pivot of the compass
card. By constructing the card frame of tubular aluminium and the central boss
of ebonite, the latter being connected to the rim by tubular aluminium arms, and
the needles being suspended by aluminium strips I obtain a frame of great strength
without unduly increasing the weight of the card when complete. The needles E
are arranged in two systems one on each side of the centre and below the card
proper, each system consisting of one (or it might be two) vertical rows. They are
held in the light aluminium brackets F which by means of the light aluminium
bands G are suspended from the radial tubular aluminium bars C at points near
the circumference.
Or the needles or magnets might be arranged in the form of two thin flat tapered
bars E as shown in Figure 4 Or they might be arranged in the form of two such
taper bars E horizontally disposed as shown in Figure 5. Or I may arrange the
needles in the well known manner shown in Figure 6 that is to say in the form of
two pairs of thin flat bars E vertically disposed, Or I may arrange them as shown
in Figure 7 that is to say with two such pairs of bars E horizontally disposed.
The brackets for holding the needles should in all cases be of aluminium and as
light as possible.
This construction of card enables me to obtain greater steadiness in the working
of the Card at sea, while the Card at the same time is particularly suitable for a
compass bowl with correctors for quadrantal and cardinal errors described in the
Specification of my Patent No 6288 of 1884.
I declare that I am aware that it is not new to arrange the needle or needles
some distance below the card and to suspend same wholly from the rim of the card

page_text: frame as such an arrangement is described in Atkin's Specification N° 4374 of 1819
and has been besides made and tried by the Admiralty in many other and more
practical forms long before 1876. I am also aware that an arrangement for
suspending the needles partly from the rim and partly from some part of the
card frame proper is described in Sir W. Thomson's Specification 1339 of 1876.
I am also aware that the employment of aluminium for compass card frames is
named in Paget's Specification No 843 of 1868 in which is also described a light
compass card having a low centre of gravity and suitable for the finest weather as
well as for stormy weather, and in which a number of short needles are arranged
one above the other in vertical planes.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is:
First A compass card having the frame proper made with tubular aluminium
rim and radial bars and with central ebonite cap and with the needles suspended
by aluminium framing wholly from the radial bars and arranged in two systems
one on each side of the centre substantially as desired.
Second-The combination of parts forming the compass card shown on the
drawing.