AN IMPROVEMENT IN COMPASSES
Year: 1860

page_text: LETTERS PATENT to John George West, of Fleet Street, in the City of
London, Ship's Compass Maker, for the Invention of "AN IMPROVEMENT
IN COMPASSES."
Scaled the 23rd October 1860, and dated the 25th April 1860.
PROVISIONAL SPECIFICATION left by the said John George West at the
Office of the Commissioners of Patents, with his Petition, on the
25th April 1860.
I, JOHN GEORGE WEST, of Fleet Street, in the City of London, Ship's
Compass Maker, do hereby declare the nature of the said Invention for "AN
IMPROVEMENT IN COMPASSES," to be as follows:-
My Invention relates to those compasses in which the bowl is filled with
liquid, for the purpose of obtaining steadiness in the card, and it consists in
the means hereafter explained for filling the bowl and maintaining it filled'
with liquid free from air or other gaseous bubbles.
I fit to the bottom of the bowl a disc, by preference of corrugated german
silver, but a disc or plate of any other substance which will perform in the
manner hereafter stated may be employed; and I screw on or otherwise fit
hermetically to the rim of the bottom of the bowl a concave or other suitably
formed plate, with an aperture for receiving a connection with an air pump or
other exhausting apparatus or engine. The top of the bowl is closed and

page_text: covered by a plate of glass, fitted and cemented air-tight. Screw plugs are
fixed to the side of the bowl, for the purpose of filling it with liquid through
one plug, and for allowing of the escape of air and any excess of liquid through
the other. The mode of filling is as follows:-The space behind the cor-
rugated plate is exhausted, and liquid, say clear water and spirit, is admitted
through one of the plugs. A tap in the connection to the air pump or other
exhausting agent is now opened and again closed, the pressure of the
atmosphere acting on the back of the plate drives out any air bubbles that
may remain in the bowl, and then the plugs are hermetically closed. Tho
connection with the air pump or other exhausting apparatus is now entirely
cut off, when there will be sufficient pressure upon the liquid in the bowl to
prevent the infiltration of air.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John George West in the Great Seal Patent Office on the
25th October 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, J, JOHN
GEORGE WEST, of Fleet Street, in the City of London, Ship's Compass Maker,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by ITer Letters
Patent, bearing date the Twenty-fifth day of April, in the year of our Lord
One thousand eight hundred and sixty, in the twenty-third year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John George West, Her special licence that I, the said John George
West, my executors, administrators, and assigns, or such others as I, the
said John George West, my executors, administrators, and 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,
use, exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for "AN
IMPROVEMENT IN COMPASSES," upon the condition (amongst others) that I, the
said John George West, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, 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.

page_text: NOW KNOW YE, that I, the said John George West, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement thereof, reference being had to the Drawings hereunto
annexed, that is to say:-
My Invention relates to those compasses in which the bowl is filled with
liquid for the purpose of obtaining steadiness in the card, and it consists in the
means bereafter explained for filling the bowl and maintaining it filled with
liquid free from air or other gaseous bubbles.
I fit to the bottom of the bowl a disc, by preference of corrugated german
silver, but a disc or plate of any other substance which will perform in the
manner hereafter stated may be employed; and I screw on or otherwise fit
hermetically to the rim of the bottom of the bowl, or concave or other suitably
formed plate, with an aperture for receiving a connection with an air pump or
other exhausting apparatus or engine. The top of the bowl is closed, and
covered by a plate of glass, fitted and cemented air-tight. Screw plugs are
fixed to the side of the bowl for the purpose of filling it with liquid through
one plug, and for allowing of the escape of air and any excess of liquid through
the other. The mode of filling is as follows:-The space between the cor-
rugated plate is exhausted, and liquid, say clear water and spirit, is admitted
through one of the plugs. A tap in the connection to the air pump or other
exhausting agent is now opened, and again closed, the pressure of the
atmosphere acting on the back of the plate, drives out any air bubbles that
may remain in the bowl, and then the plugs are hermetically closed. The
connection with the air pump or other exhausting apparatus is now entirely
cut off, when there will be sufficient pressure upon the liquid in the bowl to
prevent the infiltration of air.
Figure 1 of the accompanying Drawings is a side clevation, and Figure 2
a vertical section, of a compass constructed according to my Invention;
Figure 3 is a plan of the under side of the bowl, with the concavo plate or
cover removed. a is the corrugated disc, fitted in the bottom of the bowl b,
as shown; c is the concave plate, screwed to the bottom of the bowl; is the
screw threaded aperture, by which communication is made with the apparatus
for exhausting air; e is a glass plate, cemented air-tight on the top of the
bowl; is a screw plug, by which liquid enters; and g is a similar plug, by
which air and any excess of liquid escape from the bowl while being filled ;
h is a passage formed through the plug g, by which the last globule of air
escapes from the bowl previous to the plug being hermetically sealed.
And having now described the nature of my said Invention, and in what

page_text: manner the same is to be performed, I declare that I claim the construction
of compasses with a corrugated metal plate and a chamber at the back thereof,
substantially in manner and for the purposes herein-before described.
In witness whereof, I, the said Jolin George West, have hereunto set my
hand and seal, this Twenty-fifth day of October, One thousand eight
hundred and sixty.