A NEW AND USEFUL IMPROVEMENT IN THE MARINER'S COMPASS
Year: 1862

page_text: LETTERS PATENT to Edward Samuel Ritchie, of the State of Massa-
chusetts, of the United States of America, for the Invention of "A
NEW AND USEFUL IMPROVEMENT IN THE MARINER'S COMPASS."
Sealed the 11th November 1862, and dated the 22nd August 1862.
COMPLETE SPECIFICATION filed by the said Edward Samuel Ritchie
at the Office of the Commissioners of Patents, with his Petition and
Declaration, on the 22nd August 1862, pursuant to the 9th Section of
the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, BE IT
KNOWN, that I. EDWARD SAMUEL RITCHIE, of the State of Massachusetts, of
the United States of America, have invented "A NEW AND USEFUL IMPROVE-
MENT IN THE MARINER'S COMPASS," and I do hereby declare that the nature
of the said Invention and the manner in which the same is to be performed
are fully described,and ascertained in and by the following Specification, and
the accompanying Drawings, of which Figure 1 is a top view; and Figure 2
a vertical section of a mariner's compass provided with my Invention which
has reference to those marine compasses whose cards are immersed in a
liquid contained within a bowl or case.
The nature of the said Invention consists in the arrangement and com-
bination of an air vessel with the magnet or with the same and its card in
manner so as not only to encompass the maguet or magnets and completely
insulate the same from the surrounding liquid, but also to buoy up the card

page_text: and magnet, or the maguet or magnets, or remove more or less of the weight
thereof from the pivot.
My improvement not only prevents the magnet or magnets from becoming
oxidised by the liquid but also operates to lessen in a great degree the friction
and wear of the pivot and bearing or cap.
In the Drawings A denotes the liquid reservoir or bowl whose top (B) is a
transparent or glass plate. This reservoir when in use is to contain or be
filled with a liquid (such as water or a mixture of water and alcohol) and has
a pivot C projecting upward from the central part of its bottom. On this
pivot the compass card D is to rest and turn. To the under side of the said
card D, (it being a plate of metal suitably painted or enamelled with the
usual compass points and designating letters) an air-tight vessel or chamber E
is affixed, the magnet or magnets G being enclosed within such chamber cr
vessel. The said air vessel is peforated so as to permit the pivot (C) to
pass through it to the cap (a), and is provided with a flanger about its
center on its upper side as shown in the Drawings. The cap (a) has a flange
y extending over the card and a screw z which passes through the card and
the said flange of the air vessel, upon which is screwed a hollow frustum of a
cone H which serves to secure the cap and card and the air vessel together.
Additional screws or means may be used when necessary to secure the card to
the air vessel, such being as exhibited at s, s, in the Drawings. An elevator (I)
is placed below the conic frustum H for the purpose of lifting the cap from
the pivot when the compass is not in use. The vessel E should not only be
air-tight but its buoyant power should be such as to cause it to nearly lift
the card D with the magnet or magnets, the pressure remaining on the pivot C
being graduated so as to be of as small an amount as will suffice to cause the
card bearing or cap to remain in contact with the pivot and turn thereon with
a trifling amount of friction. From the above it will be seen that my Inven-
tion is not only a protection to the magnet or magnets against oxidation, but
is a means of buoying nearly all of the weight of the card and its magnet or
magnets relatively to the point of the pivot on which the card is supported and
traverses while the compass may be in use. When the air vessel E is
constructed entirely separate from the cardand in other respects substantially
as described, we have the means of applying my Invention to any common
liquid compass. The card may constitute the cover of the air vessel and thus
make part of the same; so also the conic frustum may constitute a portion
of the air vessel; I prefer however that the air vessel, the card and the conic
frustum be made separate from one another and be provided with means
of connection as explained.

page_text: Having thus described my Invention, what I claim and desire to secure
by Letters Patent is as follows,—
I claim the arrangement and combination of the air vessel (E) with the
magnet or magnets (G).
I also claim the combination of the said air vessel and magnet or magnets
with the card D the same being for the purposes as specified.
In witness whereof, I have hereunto set my hand and seal, this First
day of August 1862.
EDWARD SAMUEL RITCHIE. (L.S.)