A Combined Pocket Sextant, Prismatic Compass, and Clinometer.
Year: 1890

page_text: Date of Application, 1st May, 1890
Complete Specification Left, 2nd Feb., 1891-Accepted, 14th Mar., 1891
PROVISIONAL SPECIFICATION.
A Combined Pocket Sextant, Prismatic Compass, and Clinometer.
We, CHARLES BARKER and WILLIAM Edward BAKKER, trading in partner-
ship under the firm or style of Francis Barker and Son, of 12, Clerkenwell Road, in
the County of Middlesex, Instrument Makers, do hereby declare the nature of this
invention to be as follows:—
Our invention has for its object to combine a sextant and a prismatic compass, or
a sextant, prismatic compass, and clinometer, in a single instrument by means
whereof all the operations may be performed for which two or three separate
instruments have heretofore been used.
In carrying out the invention, we provide, beneath the top or bottom cover
of the box of an ordinary pocket sextant, a chamber in which the compass and
clinometer cards, with the usual adjuncts, are mounted, the necessary aperture
being provided in the cover of the box at which the cards are visible.
The usual prism and sights, for use with the compass card, are mounted on the
box in proper relation to the said aperture, and upon the exterior of the box the
necessary straight edges, for use with the clinometer, are fixed.
C. BARKER.
W. E. BARKER.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.
COMPLETE SPECIFICATION.
A Combined Pocket Sextant, Prismatic Compass, and Clinometer.
We, CHARLES BARKER and WILLIAM EDWARD BARKER, trading in partner-
ship under the firm or style of Francis Barker and Son, of 12, Clerkenwell Road,
in the County of Middlesex, Instrument Makers, do hereby declare the nature of
this invention, and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
Our invention has for its object to combine a box sextant and a prismatic
compass or a box sextant, prismatic compass, and clinometer, in a single instrument
by means whereof all the operations may be performed for which two or three
separate instruments have heretofore been used.
In carrying out the invention, we provide, beneath the top or bottom cover of
the box of an ordinary pocket sextant, a chamber in which the compass and
clinometer cards, with the usual adjuncts, are mounted, the necessary aperture being
provided in the cover of the box at which the cards are visible.
The usual prism and sights, for use with the compass card, are mounted on the
box in proper relation to the said aperture.
Reference is to be had to the accompanying drawings, forming part of this
Specification, wherein
Figure 1 is a vertical section, and Figure 2 a plan, partly in section, of a
box sextant having combined therewith a prismatic compass and clinometer.
The box sextant is of the usual construction, and comprises the box A, the
telescope B, the usual mirrors, namely the " horizon" glass C and "index
glass D, pivoted to the index arm D' terminating in a vernier working over the
limb E and adjusted by rack and pinion motion and read off by the magnifier F, all
as usual.

page_text: The prismatic compass comprises the compass card G, the sight and prism H,
dark glasses I, and hinged sight vane K, with mirror, all as usual in such instru
ments, the compass card (being mounted within an inner chamber N, fixed
beneath the cover of box A which has an aperture a in it through which the
compass and elinometer cards are viewed.
O is the clinometer dise of the onlinary construction, pivoted above the compass
earl and also provided with an aperture which is made to coincide with aperture a
in the top of fox A when the instrument is to be used as a prismatic compass, the
usual contrivances operated from the top or side of the box for holding the clino-
meter disc stationary in that position when required and for raising the compass
card off its centre when not in use.
The combined sight and prism II is carried by the usual vertically-adjustable
plate sliding in guides in the top and bottom of the box and provided with
an aperture to avoid obstructing the view through the telescope B of the
sextant, the plate & passing between the side of the box A and the dark slide /
of the telescope. The clinometer disc is read off through the magnifying prism H
which is capable of sufficient adjustment to enable it to be focussed either uponl
the clinometer dise or the compass card, as may be required.
It will be evident that by omitting the clinometer dise the combination of the
other two instruments would remain unaltered.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what mauner the same is to be performed, we declare that what we
claim is :-
The herein described combinations in one instrument, of a box sextant and pri
matic compass and of a box sextant, prismatic compass, and elinometer, substantially
as specificil.
11-4. MR
A
201
201
C. BARKER.
W. E. BARKER.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.