An Improved Instrument for Determining the Latitude of a Ship at Sea.
Year: 1885

page_text: An Improved Instrument for Determining the Latitude of a
Ship at Sea.
JAMES BOGLE (Master Mariner) Ochilview Villa, Falkirk, Stirlingshire Scotland,
I do hereby declare the nature of my invention for AUTOMATICALLY FINDING A
SHIP'S POSITION AT SEA ETC, to be as follows
A semi-sphere, hollow, made of brass, to swing on gimbals so as to maintain its
horizontal position it is loaded witli lead in the bottom, immediately inside this
brass bowl, a glass semi-sphere is slung, graduated into degrees & miles. It is an
exact semi-sphere & it is covered with a lid of brass made very thin, and a small
hole is punctured in its exact centre, to admit light or the rays of the sun.-The
glass semi-sphere is washed with nitrate of silver & the action of light or the sun's
rays through the small aperture in the centre of the lid; traces the position of the
sun at any given time or for an entire day according as the aperture is closed
or open (as it is fitted with a slide to stop the tracing of the sun's path when
desired) When it is required to have a permanent record of the sun's path, paper
sensitised shapes are inserted in the bowl.
5
A graduated are moves, on a pivot attached to the underneath part of the glass
bowl, so as to facilitate the measuring of the arc traced by the sun on any part of
the bowl,
This graduated arc is divided into 90° counting from top to bottom & is
subdivided into miles & seconds by a sliding vernier.,
The one half of the arc only is marked, the other half simply is to maintain the
equilibrium of the semi-sphere.
When it is required to read the altitude of the sun, the slide is closed, the brass
bowl turned upside down, leaving the glass bowl exposed, when the projected path
of the sun is seen distinctly inside the glass bowl the graduated are is then
adjusted to the lowest part of the projected arc, and the exact altitude is thus
obtained.
If it is noon the distance from the lowest part of the arc to the nadir of the
bowl is the zenith distance.
.
The advantages claimed for this Invention are as follows:
$
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(1) When the horizon is obscured by fog or land, an exact altitude can be had
by this instrument as no horizon is ever required;

page_text: (2) When the sun is obscured by clouds the action of light in this instrument
traces an arc similar to the sun's path in the heavens-But in this case the bowl is
kept clear of local reflection.
(3) By the use of the paper sensitised bowl permanent records of the sun's path;
amplitudes & azimuths for any date in any part of the world can be had.
LT
100K
COMPLETE SPECIFICATION.
An Improved Instrument for Determining the Latitude of a
Ship at Sea.
JAMES BOGLE (Master Mariner) Ochilview Villa, Falkirk Stirlingshire, Scotland,
I do hereby declare the nature of my invention for AUTOMATICALLY FINDING A
SHIP'S POSITION AT SEA and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:-
A semi-sphere, hollow made of brass (1) to swing on gimbals so as to maintain its
horizontal position it is loaded with lead in the bottom, immediately inside this
brass bowl, a glass (2) semi-sphere is slung, graduated into degrees & miles.-It is
an exact semi-sphere & it is covered with a lid of brass (3) made very thin, and a
small hole is punctured in its exact centre, to admit light or the rays of the sun.
. The glass semi-sphere is washed with nitrate of silver & the action of light or
the sun's rays through the small aperture in the centre of the lid traces the position
of the sun at any given time or for an entire day according as the aperture is
closed or open, as it is fitted with a slide to stop the tracing of the projected sun's
path when desired-When it is required to have a permanent record of the sun's
path, paper sensitized shapes are inserted in the bowl.
A graduated (4) arc constructed to revolve round the glass semi-sphere to
facilitate the measuring of the arc traced by the sun on any part of bowl.
This graduated arc is divided into 90°, counting from top to bottom & is sub-
divided into miles & seconds by a sliding vernier.
When it is required to read the altitude of the sun, the slide is closed, the
brass bowl turned upside down leaving the glass bowl exposed when the projected
path of the sun is seen distinctly inside the. glass bowl, the graduated arc is
then adjusted to the lowest part of the projected arc & the exact, altitude is thus
obtained.
If it is noon the distance from the lowest part of the arc to the nadir of the
bowl is the zenith distance and by applying the declination, the latitude is at once
"

page_text: found. On the accompanying sheet of Drawings consisting of one view, the
princpal parts of my Invention are denoted by letters of reference. A is a hollow
semisphere made of brass, suspended by means of arms B inside of which is slung
the glass semisphere C which is covered by the thin brass lid D, in the centre of
which is punctured a small hole e for the admittance of light. E is a graduated
arc constructed to revolve round the glass semisphere C to facilitate the measuring
of the arc traced by the sun on any part of the bowl.
Having now particularly described & ascertained the nature of my said
invention & in what manner the same is to be performed, I declare that what
I claim is
(1) The use of a darkened chamber or receptacle, which may vary in form, but
in which the sun's light is admitted through a small aperture in the covering or
top of same and by this means the elevation of the sun is determined by the
projection of its light upon a scale, which surrounds the darkened chamber or
receptacle, graduated from zero to ninety degrees, with the usual subdivisions,.
ninety being at the nadir or bottom.
(2) When the horizon is obscured by fog or land, an exact altitude can be had,
as no horizon is ever required, or when the sun is obscured by clouds, the action of
sun light in this instrument traces an arc similar to the sun's path in the heavens.
(3) By the use of the paper sensitised shapes permanent records of the sun's
path, amplitudes & azimuths for any date in any part of the world can be had.
Dated this twenty-fifth day of May 1886