AN IMPROVED MARINER'S COMPASS CHIEFLY DESIGNED FOR USE IN IRON VESSELS communicated to him by
Year: 1883

page_text: LETTERS PATENT to William Robert Lake, of the firm of Haseltine Lake
& Co, Patent Agents, Southampton Buildings, London for an Invention of
"AN IMPROVED MARINER'S COMPASS CHIEFLY DESIGNED FOR USE IN IRON
VESSELS communicated to him from abroad by Ernest Bisson, of Paris,
France
"
PROVISIONAL SPECIFICATION left by the said William Robert Lake at the
Office of the Commissioners of Patents on the 22nd June 1883.
WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake, and Co., Patent Agents,
Southampton Buildings, London, "AN IMPROVED MARINER'S COMPASS CHIEFLY
DESIGNED FOR USE IN IRON VESSELS [a communication to him from abroad
by Ernest Bisson, of Paris, France]
"
This invention relates to an improved mariner's compass shewing the direction
of the magnetic meridian upon iron ships.
The form and arrangement of the said compass may be varied without departing
from the nature of the said invention.
In carrying the said invention into practice I provide a copper box containing
two compass cards and made in two parts joined together by screws. This box
may, if desired, be of the same diameter from top to bottom. The said box has
a copper lid closing by means of a bayonet joint and graduated on the top to
permit the addition of an alidade. A piece of plate glass is fitted in the said lid
and is perforated in the centre and provided with a barrel or bush permitting the
passage through its centre of the rod of the internal alidade. This glass is also
provided on the outside with a bearing to serve if necessary as a support for an
exterior alidade.
A circular suspension piece is provided in the shape of a quadrant supporting
the instrument by means of two journals fixed upon the said box. I also provide
a central circular frame made of copper the upper part of which is provided
with two cross-bars, one of these bars carrying the pivot-post for one of the
needles and the other carrying the internal alidade,
This alidade is provided with two bar magnets and is movable upon one part of
the cross bar of the said frame by means of a rigid rod or bar the lower part of

page_text: which is guided in the bearing of the cross-bar, the upper part of the same being
guided by the said barrel or bush. A milled wheel or knob is fitted on the said
rod and can be removed to allow the lid to be taken off if required. This knob
is designed for turning the alidade and its magnets. The two needles are each
supported upon a pivot post provided with a screw-thread for regulating the
height of the said needles, and compass cards are fixed to the said needles.
These needles are of different mass. A lead or copper weight is secured to the
lower part of the compass-box to retain the instrument in its proper position.
Two mirrors are provided which are connected by means of a hinge forming a kind
of double mirror which is supported by a pillar by means of a knee or knuckle-
joint and a screw is passed through the said pillar to regulate the inclination of
the mirrors. A horse hair is stretched vertically and forms a guide line for the two
needles. The said pillar, the mirrors, and the horse hair must be arranged upon a
diameter perpendicular to that of the circular frame, so that the readings may
be easily effected from the mirrors.
The said invention therefore consists essentially in the use of two magnetic
needles of equal length but of different mass, independent of each other, and
having their contres upon the same vertical line. As it is indispensable that the
deviating forces of the ship should be considered as acting equally upon these two
needles, it is necessary that the said needles should not be placed more than ten
or.fifteen centimetres from each other; the less the distance between them the
better will be the result, providing the action which they have upon one another
does not prevent them maintaining the direction of the meridiau in the absence
of deviating forces.
The following are characteristic features of the said invention that is to say,
the placing of two needles in the same box and the reflection of the indications
of the two cards in an articulated, or non-articulated mirror or in a prism in order
to be able to read the indications on the two cards simultaneously, and the arrange-
ment of the circular suspension piece upon a horizontal plane equally distant
from each of tho two cards in such a manner that the two needles are protected
both from oscillations and shocks,

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Robert Lake in the Great Seal Patent Office on the
19th December 1883.
26
'WILLIAM ROBERT LAKE of the firm of Haseltine, Lake & Co Patent Agents,
Southampton Buildings, London AN IMPROVED MARINER'S COMPASS, CHIEFLY
DESIGNED FOR USE IN IRON VESSELS "-A communication to me from abroad by
Ernest Bisson, of Paris, France
This invention relates to an improved mariner's compass shewing the direction
of the magnetic meridian upon iron ships, and comprises the novel construction and
arrangement of parts as hereinafter described
The said invention is illustrated in the accompanying drawing in which:-
A indicates a copper box containing two compass cards and made in two parts
joined together by the screws A¹. This box may, if desired, be of the same
diameter from top to bottom. The said box has a copper lid B closing by means
of a bayonet joint and graduated upon its upper periphery B₁ to permit the
employment of an alidade.
Ĉ indicates a piece of plate glass fitted in the lid B, the said piece of glass being
perforated in its centre and provided with a barrel or bush C¹ permitting the
passage through its centre of the rod of the internal alidade This glass is also
provided on the outside with a bearing to serve, if necessary, as a support for an
exterior alidade
D indicates a circular suspension piece supporting the instrument by means of
two journals fixed upon the said box A. E indicates a central circular frame of
copper the upper part of which is provided with two cross-bars E, F, one of these
bars carrying the pivot-post for one of the needles, and the other carrying the
internal alidade G.
This alidade is provided with two magnetic bars and is movable upon a part E¹
of the cross bar E* of the said frame, by means of a rigid rod or bar G³, the lower
part of which is guided in the bearing E' of the cross-bar E*, the upper part of the
same being guided by the said barrel or bush C. H indicates a milled knob fitted
on the said rod, which knob can be removed to allow the lid B to be taken off
when required. This knob is designed for turning the alidade G and its magnets.
The two needles M M² are of different mass and are supported upon the pivot-
posts J, J provided with screw-threads for regulating the height of the said .
needles to which are fixed the compass cards K K².
N indicates a lead or copper weight secured to the lower part of the compass-
box to retain the instrument in its proper position
O, O indicate two mirrors which are connected by means of a hinge 0¹ and
supported on a pillar P by means of a knee or knuckle-joint Q and a screw S
which is passed through the said pillar to regulate the inclination of the mirrors.
Instead of the mirrors a prism may be used.
R indicates a horse hair stretched vertically and forming a guide line for the
two needles. The said pillar P, the mirrors O, and the horse hair R, which in
order to simplify the drawing are shewn in the same plane as the frame E, must
be arranged perpendicularly upon the circular frame, so that the readings may be
easily effected from the mirrors.
The essential feature of this invention is the employment of two magnetic
needles of equal length but of different mass, independent of each other, and having
heir centres upon the same vertical line. As it is indispensable that the deviating
forces of the ship should be considered as acting equally upon these two needles, it

page_text: is necessary that the said needles should not be placed more than ten or fifteen
centimetres from each other. The less the distance between them the better will be
the result, providing the action which they have upon one another does not prevent
them from maintaining the direction of the meridian in the absence of deviating
forces.
Other important features of the invention are the arrangement of two needles in
the same box and the reflection of the indications of the two cards in mirrors, or in
a prism, in order to be able to read the indications of the two cards simultaneously,
and the arrangement of a circular suspension piece upon a horizontal plane equally
distant from each of the two cards, in such a manner that the two needles are
protected both from oscillations and shocks.
-It-is-indispensable--that the alidade should be placed inside the box so_that_its
movement should not be interfered with by the circular suspension piece and the
journals of the box, which journals are in nearly the same horizontal plane as the
magnetic bars of the said alidade G. Caro is required in the construction of such
an instrument to ensure that the action of the magnets of the alidade should be
the same for both needles. The latter being of unequal mass, it is obvious that
the plane in which the magnets are situated should not be at equal distances from
each of the two needles.
The form and arrangement of the improved compass may be modified without
departing from the nature of this invention
-
Having thus fully described the said invention as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it understood
that I. claim
First The improved mariner's compass, substantially as herein before described
-and-shown in the accompanying-drawing, for showing the deviation of the
magnetic meridian upon iron ships.
Second The employment of two magnetic needles of equal length, but of different
mass and independent of each other, the centres of the said needles being placed
upon the same vertical line.
Third The arrangement inside the box of a movable alidade carrying upon its
extremities two magnetic bars, substantially in the manner herein before described.
Fourth The arrangement of two needles in the same box, and the reflection of
the indications of the two cards in a prism, or in mirrors having different
inclinations; for the purpose specified.
Fifth The arrangement of the circular suspension piece upon a horizontal plane
equally distant from the two cards.
In witness whereof I the said William Robert Lake have hereunto set my hand,
and scal this nineteenth day of December in the year of our Lord' one thousand
eight hundred and eighty three.
W ROBT LAKE (L.S.)