Improvements in Ships' Course Correctors.
Year: 1889

page_text: Date of Application, 13th Feb., 1889
Complete Specification Left, 7th Oct., 1889-Accepted, 30th Nov., 1889
PROVISIONAL SPECIFICATION.
Improvements in Ships' Course Correctors.
I, GEORGE WILSON HEATH of Crayford in the County of Kent Nautical Instrument
Maker do hereby declare the nature of this invention to be as follows:-
:-
In the instrument known as Heath's London Polaris Ships' course corrector and in
other such like instruments for finding the true or magnetic course I according to this
invention effect the following improvements. Heretofore such instruments have not
been conveniently available except during certain hours of the day and in certain
latitudes. Now one object of this invention is to render them wholly available for day
use during any part of the day and in all latitudes. For this purpose I provide a
dumb card divided to 90° and 180° for each half circle, the 180° divisions being used
in connection with the shadow pin and by the aid of tables, while the 90° divisions
are used in connection with the upper latitude time & declination dials and vanes.
The upper time dial is divided into two 180 degree divisions each degree corre-
sponding to four minutes of time divisions. On this time dial I provide folding
or hinged azimuth sights both mounted on a movable base or bar, the hair line sight
being so long as to more than reach over the diameter of the dial when folded nearly
down, and fitted with a horizontal sliding hair line or equivalent device. This part
has a suitable number of graduations each way from the centre corresponding to the
declination tables "contrary name to latitude" and " same name as latitude." When
this part is inclined towards the base or bar on which it is mounted the hair line
shadow falling on a line along the centre of that bar the instrument can be used when
the sun is at or near its zenith, the bar being suitably graduated. The. other or
sight vane is by preference also folding or hinged and is provided with a vertical
slit and a horizontal crosslit. The base or bar for these sights may be made with or
as a tube for sighting the sun or a star more conveniently; or I may make such sight
tube a fixture on the time circle or standard. For the exact vertical mounting of the
instrument I connect a plumb weight to a bottom flange which by screws is adjustable
relatively to a flange on a standard the bottom pivot of which bears on the said
bottom flange. The gimbals are at about the level of the dumb card, which has the
usual arrow pointer or hand.
Dated th 19th 1000
GEORGE WILSON HEATH.
By Jensen & Son,
77, Chancery Lane, London, W.C., Patent Agents.
COMPLETE SPECIFICATION.
Improvements in Ships' Course Correctors.
1, GEORGE WILSON HEATH, of Crayford in the county of Kent, Nautical Instrument
Maker, 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 :-
"Heath's
This invention consists in improvements in the instrument known as
London Polaris Ship's Course Corrector" and in other such like instruments for
finding the true or magnetic course.
Heretofore such instruments have not been conveniently available except during
certain hours of the day and in certain latitudes. Now one object of this my invention
is to render them wholly available for day use during any part of the day and in all
latitudes.
In the accompanying drawings I have shown the invention applied to a
•
"Heath's

page_text: London Polaris Ship's Course Corrector," fig. 1 being a perspective view of same,
and fig. 2 a side view of same with the lower or box part in section, Fig. 3 is a
sectional elevation to illustrate the use of the shadow pin in connection with part of
the apparatus..
A is the arrow pointer on the dumb-card A' which is divided as heretofore to 90°
and 180° for each half circle, the 180° divisions being used in connection with the
shadow pin U, fig. 3 and with the aid of tables, while the 90° divisions are used in
connection with the upper latitude, time, and declination dials and vanes:
The upper time dial H is divided into two 180° divisions, each degree corresponding
to four minutes of time divisions. On this time dial H are provided the folding or
hinged azimuth sighis C and F', both mounted on the base or bar D¹ which is provided
with a pointer D passing through a slot in the sight. F and is movable round its
centre pivot D². The hair line sight C is so long as to more than reach over the
diameter of the dial H when folded nearly down and is fitted with a horizontal slide G
with hair line G¹, the latter being a thin wire or equivalent devico reaching across
the graduations of the sight C. These graduations proceed in a suitable number cach
way from the centre or zero o, corresponding to the declination tables "contrary name
to latitude" and "same name as latitude," these terms being also marked on the
sight C. When this part C is inclined towards the base or bar D¹ on which it is
mounted, the shadow of the hair line G falling on a line along the centre of the
bar D' the instrument can be used when the sun is near its zenith and the bar D¹
may for this purpose be suitably graduated.
The other or sight vane F1 is by preference also folded or hinged to the base or
bar D and is provided with the usual vertical slit F, and in addition thereto with a
horizontal cross slit F.
The base or bar D₁ for these sights and F¹ may be made with or as a. tube for
sighting the sun or a star more conveniently; or I may make such sight tube a
fixture on the time circle II or on the standard T.
"
For the exact vertical mounting of the instrument I connect a plumb weight 1',
fig. 2 to a bottom flange I which by screws K is adjustable relatively to a flange L on
the standard T, the bottom pivot M of which bears on the flange 1; V is a peg or
tommy" for turning the screws K. To keep the instrument steady in the upright
position when not in use the lever N is provided, which at one end with a point N
enters a conical recess in the bottom of the weight I and at the other end is
adjustably held by a rod which with a screwed part passes through the corre-
spondingly tapped bracket P fixed to the side of the box Q. The rod Ổ has a milled
head 01.
The gimbals are as usual at about the level of the dumb card A¹ which has the
usual arrow pointer or hand A.
In order to use the instrument with the sun and local time the instrument is placed
in a line with the ship's keel and the arrow pointer A fixed to the variation east or
west as marked on the compass dial A'. The latitude half circle B is then fixed in the
position due to the known latitude of the place, using the white line c marked on the
centre upright or standard T, as the pointer. Note now the apparent time to within
four minutes and set the sight vane pointer D on the end of the base D₁ to it (the
time dial H being divided to four minutes as stated). Next move the compass dial A¹
by taking hold of the two knobs A³ thereon, until the shadow of the wire line E on the
sight C falls upon the vertical slit F in the sight vane F.
When it is necessary to take the declination into consideration (for instance when
using the instrument early in the morning or late in the afternoon in equatorial
waters) then the cross wire G on the slide G is set to the degrees marked on the
sight of the wire line E according to the sun's declination, then proceed as aforesaid
until the shadow thrown by the cross wire G coincides with the cross cut 2 in the
sight vane.
As the time circle H is also divided to 180° it may be used with the aid of the
sights to determine the correct or magnetic course according to Burdwood's or
other tables apart from the dial A.
J.,

page_text: In order to use the instrument with a star the time circle H is clamped horizontally
and the pointer A to the ship's head. The star is then sighted while using the are
divided to 180° on the time circle H to determine the position in the usual manner.
To use the instrument without the sun by a distant object the bearings of which are
known, the circle H is clamped horizontally and the sight vane pointer D placed
to XII or zero. The pointer A is then fixed to the known bearing of the distant object
and then the dial A¹ is moved by taking hold of the knobs A2 until one can sight the
distant object through the sight vane F. The difference between the dial A' and the
compass dial on the ship is the deviation.
To use the shadow pin U, Fig. 3, the set screw T¹ is turned back so that the
standard T with all the parts thereon can be lifted off the peg M' of the centre and
the shadow pin put on it, the latter being for this purpose formed with a bottom
recess.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is;
-
1. Providing the hair line sight C with divisions and with a slide having a cross
bair line, substantially as and for the purpose set forth.
2. Providing the sight vane F" with a cross line F² substantially as and for the
purpose set forth.
3. Making the base or bar D₁ with graduations and, if desired, in the form of
a sight tube, or providing a sight tube in connection therewith, substantially as and
for the purpose set forth.
4. Providing the upper time dial H with the divisions named.
5. Providing the lower part of the instrument with an adjustable plumb weight,
substantially as and for the purpose set forth.
6. The improved construction of ship's course corrector shewn on the drawings.
Dated this 7th day of October 1809.
LO
ᎧᎧ.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.