AN IMPROVEMENT OR IMPROVEMENTS ON SHIPS' COMPASSES
Year: 1832

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GRANT
PRESTON, of the Minories, in the City of London, Nautical Brazier, send
greeting.
WHEREAS His present most Excellent Majesty King William the Fourth,
by His Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Thirtieth day of May, in the second year of His reign, did,
for Himself, His heirs and successors, give and grant unto me, the said Grant
Preston, His especial licence, sole privilege and authority, that I, the said
Grant Preston, my exors, admors, and assigns, or such others as I, the said
Grant Preston, my exors, admors, or assigns, should at any time agree with,
and no others, from time to time and at all times during the term of years
therein expressed, should and lawfully might make, use, exercise, and vend,
within England, Wales, and the Town of Berwick-upon-Tweed, my Invention
of "AN IMPROVEMENT OR IMPROVEMENTS ON SHIPS' COMPASSES;" in which said
Letters Patent is contained a proviso that I, the said Grant Preston, shall
cause a particular description of the nature of my said Invention, and in what
manner the same is to be performed, to be enrolled in His said Majesty's
High Court of Chancery within two calendar months next and immediately
after the date of the said in part recited Letters Patent, as in and by the
same, reference being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Grant Preston, do hereby declare that the nature of my said Invention, and
in the manner in which the same is to be performed, are fully described and
ascertained in and by the following description thereof, reference being had

page_text: to the Drawing hereunto annexed, and to the figures and letters marked
thereon (that is to say) :-
My Invention consists of improvements or additions to the common compass
to prevent the vibration to which the compass is now subject, and which at
present tends to prevent the correct action of the needle. These improvements
or additions consist of tubes or rings either attached to the ordinary cap
which contains the agate, or the same may be attached to the card by means
of arms. The pin on which the card is suspended passes up through these
tubes, and when the card has a tendency to vibrate, in consequence of any
motion to the vessel, the lower end of the tube will come in contact with the
pin and stop such vibration. At the same time there will be sufficient play to
insure the action of the needle, and thus will compasses with my improve-
ments applied be more correct in their action. In order that my Invention may
be fully understood and carried into effect, I will proceed to describe the
Drawing hereunto annexed.
DESCRIPTION OF THE DRAWING.
Figure 1 represents a section of a common steering compass having my
improvements applied thereto, a being the usual card, and 6 the needle.
c is the ordinary cap, which contains the agate. d is an upright pin or point,
on which the cord a is suspended in the usual manner. e is a small tube,
which descends down the pin d. This tube is connected to the card a by
means of screws or rivets passing though the arms f, f, as is shewn in the
Drawing; or in place of this short tube a ring or perforated plate may be used,
the object being evident, that of preventing the vibration of the card a by the
lower end of the tube e coming in contact with the suspending pin d, as will
be readily understood by inspecting the Drawing, and thus preventing further
vibration than is necessary to insure free action to the needle, and it will
be evident that very slight friction will be produced by the contact of the tube
e and the pin d.
Figure 2 shows the manner in which the tube e is attached to the ordinary
cap c. In the interior of the cap c is cut a screw, and on the end of the tube e
is also cut a screw, which screws into the cap c, and thus connects the cap c
and the tube e. It will be seen that both these tubes are shewn in section,
that the construction and position of the various parts may be clearly seen..
Figures 3 and 4 show my improvement applicable to the description of
compass wherein is used what is termed a dipping needle. Fig. 3 being a plan
of the upper side of the card, and Fig. 4 an edge view of the card shown in
section, 6 being the needle, a the card, c the cap, e the tube, and f, f.

page_text: The
the arms by which the tube is connected to the card by means of screws.
needle in this compass, in place of being affixed to the card, as is the case
with the last described, is suspended on two axes g, g, which are supported
by the bearings h, h, which are affixed by screws to the card a, and the circular
plate i, affixed to the cap c, receives the other ends of the axes. j, j, are two
upright pieces affixed to the needle, and through these the axes pass, by which
means the needle is permitted to swing up and down, as is usual with this
description of compass. The tube e is similar to that described in Fig. 2, and
has arms f, f, similar to those in Fig. 1. d is the pin on which the compass
is suspended. In using a compass having my Invention applied thereto, it
will be evident that in case of any particular motion to the vessel, and which
would cause vibration to the card of an ordinary compass, and would thus
prevent the needle pointing correctly, such vibration would be immediately
checked by the lower part of the tube e coming in contact with the pin d, and
enable the needle to be more correct in its pointing.
Having now described the nature of my Invention, and also the manner
of making or producing the same, I would have it understood that what I
claim as my Invention is, the application of the tube e, whether the same be
connected to the card by means of arms f, f, or fastened directly to the cap c,
with a view to prevent the vibration of the card and needle, as above described,
but I lay no claim to the other parts shewn and described.
In witness whereof, I, the said Grant Preston, have hereunto set my
hand and seal, this Thirtieth day of July, in the year of our Lord
One thousand eight hundred and thirty-two