IM- PROVEMENTS IN MARINE COMPASSES, AND IN APPARATUS APPLICABLE THERETO
Year: 1855

page_text: LETTERS PATENT to Andrew Small, of Glasgow, in the County of Lanark,
North Britain, Ship Chandler, for the Invention of "IMPROVEMENTS IN
Sealed the 8th May 1855, and dated the 1st March 1855.
PROVISIONAL SPECIFICATION left by the said Andrew Small at tho
Office of the Commissioners of Patents, with his Petition, on the 1st
March 1855.
I, ANDREW SMALL, of Glasgow, in the County of Lanark, North Britain,
Ship Chandler, do hereby declare the nature of the said Invention for "IM-
PROVEMENTS IN MARINE COMPASSES, AND IN APPARATUS APPLICABLE THERETO," to
be as follows, that is to say:-
This Invention relates to various improved mechanical applications and
arrangements connected with the mariner's compass, and affecting the entire
binnacle. The actual compass portion is the same as is at present usually fitted
up on ship-board, but the adjusting magnet or magnets for the correction of
the needle's deflection are so disposed in the binnacle case that the ship-master
or his officer may at any time set them as required. A long vertical screw
is passed down the interior of one or more sides of the binnacle case, being
capable of revolution by the action of a handle to be shipped on the upper

page_text: end when necessary. This screw spindle carries a nut with a holding piece
for carrying the adjusting magnet, which is thus disposed instead of being
placed on the ship's deck. When the ship is to be set to any particular course,
the north, for example, the screw spindle of the adjusting magnet is turned
until the magnet is sufficiently elevated for the purpose, the amount of
elevation being shewn by an external graduated scale on the binnacle case, to
which scale the edge of a dial piece fast to the internal magnet nut is made
to point. This dial piece is graduated with the compass points, and it carries
an index hand, which can be set round externally by hand. Above this dial is
a segmental or semicircular scale, graduated to degrees, and having suspended
before it a small index pendulum, which thus points out the amount of
inclination of the vessel. When the vessel's inclination causes deflection of
the compass needle, this is compensated for by setting the adjusting magnet
accordingly; and when the amount of deflection due to a certain extent of the
vessel is known and tabulated for the use of the ship-master, he can of course
effect the proper compensation at any time and under all circumstances. The
external dial index is always correspondingly set at each adjustment, so as to
point out what amount of magnetic adjustment was last made. One dial is of
course fitted up for north and south adjustinent, and another for east and west.
In addition to these modifications, a dumb compass card is adjusted above
the binnacle for the purpose of ascertaining the exact compass deviation at
sea, or bearings of headlands and other points. This compass card is fitted up
with wheel and pinion, or other gearing, so that it can be set round as required
to any point. This dumb card is swung athwartship, its centres of suspension
being fore and aft, so that its vibration is in one direction only, and its points
can be read with facility. When this test is to be applied, the dumb card is set
round until it coincides with the real compass card beneath; in this condition
a shifting arm, carrying proper sights, and set upon a central stud on the dumb
card, is turned round until the sun's azimuth is obtained, and the actual
amount of deflection is then found in the usual manner. By a further modifi-
cation of this arm arrangement, a vertical graduated piece is carried upon the
arm's extremity, and standing up at right angles thereto. These vertical
graduations are on the edge of a slot, over which a hair line piece is adjustable.
Thus when put to use, the sun's light causes the index hair line to throw its
shadow down upon the horizontal arm on the card's centre beneath, and this
arm being also graduated, the result gives the sun's altitude when trented in
reference to the proper tabulated matter.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Andrew Small in the Great Seal Patent Office on the
1st September 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ANDREW
SMALL, of Glasgow, in the County of Lanark, North Britain, Ship Chandler,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the First day of March, in the year of our Lord
One thousand eight hundred and fifty-five, in the eighteenth year of Her
reign, did, for Herself, Her licirs and successors, give and grant unto me, the
said Andrew Small, Her special license that I, the said Andrew Small, my
executors, administrators, and assigns, or such others as I, the said Andrew
Small, 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, usc, 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 COM-
PASSES, AND IN APPARATUS APPLICABLE THERETO," upon the condition (amongst
others) that I, the said Andrew Small, 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 Andrew Small, 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 to various improved mechanical applications and
arrangements connected with the mariner's compass, and affecting the entire
binnacle or holding case of the compass. The actual compass portion is the
same as is at present usually fitted up on ship-board, but the adjusting magnet
or magnets for the correction of the needle's deflection or derangement are so
disposed in the binnacle case that the ship-master or his officer may at any
time set them as required. A long vertical screw is passed down the interior
of one or more sides of the binnacle case, being capable of revolution by the
action of a handle to be shipped on the upper end when necessary. This
screw spindle carries a nut with a holding piece for carrying the adjusting

page_text: magnet, which is thus disposed instead of being placed on the ship's deck.
When the ship is to be set to any particular course, the north, for example, the
screw spindle of the adjusting magnet is turned until the magnet is sufficiently
elevated for the purpose, the amount of elevation being shown by an external
graduated scale on the binnacle casc, to which scale the edge of a dial picco
fast to the internal magnet nut is made to point. This dial piece is graduated
with the compass points, and it carries an index hand which can be set round
externally by band. Above this dial is a segmental or semicircular scale,
graduated to degrees, and having suspended before it a small index pendulum,
which thus points out the amount of inclination of the vessel. When the vessel's
inclination causes deflection of the compass needle, this is compensated for by
setting the adjusting magnet accordingly; and when the amount of deflection
due to a certain extent of the vessel is known and tabulated for the use of
the ship-master, he can of course effect the proper compensation at any time
and under all circumstances. The external dial index is always correspondingly
set at each adjustment, so as to point out what amount of magnetic adjust-
ment was last made. One dial is of course fitted up for north and south
adjustment, and another for east and west. In addition to these modifications,
a dumb compass card is adjusted above the binnacle, for the purpose of
ascertaining the exact compass deviation at sea, or bearings of headlands and
other points. This compass card is fitted up with wheel and pinion, or other
gearing, so that it can be set round as required to any point. This dumb card
is swung athwartship, its centres of suspension being fore and aft, so that its
vibration is in one direction only, and its points can be read with facility.
When this test is to be applied, the dumb card is set round until it coincides
with the real compass card beneath. In this condition a shifting arm, carrying
proper sights, and set upon a central stud on the dumb card, is turned round
until the sun's azimuth is obtained, and the actual amount of deflection is
then found in the usual manner. By a further modification of this arm
arrangement, a vertical graduated piece is carried upon the armi's extremity,
and standing up at right angles thereto. These vertical graduations are on
the edge of a slot, over which a hair line piece is adjustable. Thus, when
put to use, the sun's light causes the index hair line to throw its shadow down
upon the horizontal arm on the card's centre beneath, and this arm being
also graduated, the result showing the sun's altitude is at once pointed out
thereon.
And in order that my said Invention may be properly understood, I shall
now proceed to describe the several explanatory Figures on the Sheet of
Drawings hereunto attached.

page_text: Figure 1 on my Sheet of Drawings is a complete elevation of a ship's
binnacle as fitted up with one modification of my improved compass arrange-
ments, but with one of the binnacle doors open to show the internal details of
the adjusting magnets. Figure 2 is a sectional plan of the binnacle, corre-
sponding, showing the two adjusting magnets as disposed at right angles to
cach other, one running fore and aft and the other athwartship. Figure 3 is
an external plan of the binnacle complete. Figure 4 is an elevation of another
modification of compass binnacle, with the door open to show the internal
arrangements; Figure 5 is an external plan of the same; and Figure 6 is a
sectional plan, showing four adjusting magnets in position, two running fore
and aft and two athwartship. In the modification represented in Figures
1, 2, and 3 on my Sheet of Drawings, the binnacle case or compass holder A
is constructed according to the general form hitherto in use, the magnetic
needle or actual indicating compass being contained in the cylindrical case B
on the top of the wooden binnacle, and fitted with side reflecting lights C and
an aft window D for the steersman to see by. The fore and aft adjusting or
correcting magnet is at E, in the interior of the binnacle case, and the athwart-
ship adjusting magnet is at F. Both of these magnets are fitted up in the
same manner in every respect as they are intended for effecting precisely
similar objects, the direction of adjusting or corrective action only being
different. Each of the magnets E, F, is encased in brass, and it is attached by
its inner side to an adjustable retaining nut-piece or holder G, H, through
which nut the vertical screwed spindle I is passed. The nut holder is made to
fit to the vertical groove or slot of the long metal guide piece J, attached to
the side of the binnacle, and answering as well for holding the screw spindle.
In this condition the adjusting magnets for both directions are retained in an
accurate horizontal position, or at a true right angle with the longitudinal
centre line of the binnacle. When the ship-master or his officer wishes to
effect an adjustment of the compass needle either in the fore and aft or athwart-
ship line, he opens the corresponding door of the binnacle case, and, shipping
a handle upon the upper squared end of the proper screw spindle, he turns the
spindle in one direction or the other, and thus elevates or depresses the
corrective magnet E or F, until the necessary corrective influence has been
brought to bear upon the indicating needle of the compass. The set or vertical
position of the corrective magnet is indicated by a vertical graduated scale K,
attached to the face of the inner portion of the binnacle; thus, as the magnet
is raised or lowered, its upper edge points out upon this scale the exact
position to which the adjustment has been carried, showing also the distance
of the corrective magnet from the centre of the compass needle above. The

page_text: top of the conical compass case carries a semicircular scale L graduated to
degrees, before which is suspended the little index pendulum M, so that
whatever rolling inclination of the vessel occurs is at once pointed out, and
the officer of the ship can then compensate, by means of his magnetical
adjustment, as herein-before described, for whatever deranging influence may
thus be exerted upon the compass needle. The shallow cylindrical case N
carries a "dumb compass card," clearly exposed to the eye of the steersman.
It is swung on centres O athwartship only, and is fitted with any convenient
circular adjustment, as a large wheel and thunib pinion, worm and worm wheel,
or other mechanical contrivance. When this dumb card is to be used, it is set
round by hand until its indications coincide with those of the real acting
compass card of the magnetic needle beneath it. When this has been done
the vertical sight apparatus P, Q, is put to use for obtaining the sun's azimuth.
This apparatus P, Q, consists of a short horizontal swivel arm, free to move
upon a central stud carried by the dumb card, and having at its two opposite
ends the hinged sight pieces P, Q, vertically slotted. These pieces P, Q,
being turned up into a vertical position, as here indicated, by their bottom
hinges, their carrying arm is turned round until the sun's azimuth is
obtained, and the actual magnetic. compass needle deflection is then found
in the usual manner. As here indicated, the vertical hinged piece Qis
graduated upon one edge of its slot, and over this slot is a hair line piece R
adjustable freely up and down. Thus the sun's light causes the index hair
line to throw down its shadow upon the horizontal arm on the dumb card
centre, and this arm being graduated, the sun's altitude is at once obtained.
In the modification of my compass arrangements, delineated in Figures 4, 5,
and 6 on my Sheet of Drawings, I have four separate adjusting or corrective
magnets A, B, C, D, the actual indicating compass needle being in the caso
at E, in the interior of the body of the binnacle, and the steersman can see
his compass card through the upper window F in the binnacle case. The
respective corrective magnets in this arrangement are so set that two are near
the top and two near the bottom of the binnacle; the two opposite magnets
are in this way at two different levels as regards each other, the magnet A,
for instance, being at the lower part of the binnacle, and the magnet C at the
upper part; the same relation is observed between the magnets B, D. The
effect of this disposition is, that a corrective influence being exerted both above
and below the compass needle, the derangement arising from the inclination of
the ship is more fully counteracted. Each of the four corrective magnets is
held in position by a traversing nut-piece, as at G, the adjusting shift being
effected as in the former example by the screw spindle H.

page_text: With this arrangement of four corrective magnets the ship's officer has a
more complete control over the indicating compass needle's deflections, as he
can set or adjust on all four sides of the binnacle. The plain top of the bin-
nacle carries a semicircular scale and pendulum index I, as in my previous
example, for indicating the ship's inclination in the simplest manner. This
binnacle is fitted up with a dumb card J, as in the former example. On the
centre stud of this dumb card is a horizontal arm, each end of which acts as a
pointer for indicating north and south. The moveable centre on the dumb
card carries a segmental or semicircular graduated scale K, indicating the
latitude. This segmental scale is graduated from the centre to each end to
sixty degrees or more, indicating north and south latitude. This scale K
carries an adjustable slide piece L, having a vernier thereon, and capable of
being clamped in any required position. This slide piece forms the support of
a complete circular scale M, or graduated dial, the graduations representing the
hours and their subdivisions, and being on both sides and the inner edge or
the ring. The ring M has upon it a diametrical bar supporting a central slide
N. A small metal piece O is also attached to the ring M, for the purpose of
receiving the shadow, when from the position of the sun it is lost upon the dial
ring itself. This apparatus is most convenient and effective for showing at
once the actual error of the compass needle, or the error occuring irrespective
of local derangement. Supposing the ship is sailing in north latitude, the dumb
card is set, in the first instance, to correspond with the actual indicating com-
pass; the slide picce L is shifted to the proper latitude corresponding to the
north point. The whole apparatus is then turned round until the shadow of
the stile N falls upon the hour, as indicated upon the dial ring M, at which
hour the observation is being made. Then the discrepancy found to exist
between the north point of the dumb card and the north point of the horizontal
arm gives the whole departure of the compass needle from the truth. It is
obvious that this apparatus fulfils in.a more advanced degree the office of the
sight apparatus represented in my previous modification of binnacle. With a
hair line fitted to the dial ring, the segmental scale acts as an eye-piece to pro-
duce the same result as already described in reference to Figures 1, 2, and 3
on my Sheet of Drawings.
Having now described and particularly ascertained 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

page_text: 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 and construction of marine compasses, as
herein-before described.
Second, the system or mode of effecting the corrective adjustment of marine
compasses by means of fore and aft and athwartship adjustable magnets, as
herein-before described.
Third, the application and use of one or more adjustable corrective magnets
on each of the four sides of the binnacle case for counteracting the deflection
or derangement of the indicating compass needle.
Fourth, the application and use of opposed or opposite corrective magnets
disposed one above and one below the compass needle's level.
Fifth, the application and use of vertical or segmental graduated scales for
indicating the set or adjustment of the corrective magnets, as herein-before
described.
Sixth, the system or mode of effecting the proper corrective adjustment of
the shifting magnets for the ship's inclination by the aid of a pendulous index
and segmental scale.
Seventh, the application and use of a dumb compass card and sight appa-
ratus for obtaining the sun's azimuth and altitude, as herein-before described.
Eighth, the system or mode of ascertaining the whole error of the indicating
compass needle by means of a dumb compass card, and adjustable stile and
graduated latitude and hour or time scales, as herein-before described.
In witness whereof, I, the said Andrew Small, have hereunto set my
hand and seal, this Thirtieth day of August, One thousand eight
hundred and fifty-five.