Improvements in Off-shore Distance Indicators.
Year: 1893

page_text: Date of Application, 12th Jan., 1893
Complete Specification Left, 19th May, 1893—Accepted, 24th June, 1893
PROVISIONAL SPECIFICATION.
Improvements in Off-shore Distance Indicators.
I, EDWIN BAKER, of 32, Claude Road, Cardiff, in the County of Glamorgan,
Master Mariner, do hereby declare the nature of this invention to be as follows:-
The object of this invention is to construct an improved apparatus for readily
determining a ship's distance from an object, such as a point of land, a lighthouse
or a light-vessel.
It consists of a flat base card or plate having a disc with a central point around
which is drawn a number of circles to represent miles and portions of iniles;
through the centre of these circles a line is drawn called the line of ships course
with ships head marked at one end; outside the circles of distance is an annular
ring marked with the degrees or points of the compass, which may be adjustable to
the ships course; attached to the central point are two bars so constructed that
they cross at the centre like a pair of scissors and their inner edges are capable of
being placed close together so as to form one diametrical bearing line right across
the centre of the instrument, when separated their inner edges form two diametrical
bearing lines crossing each other and the distance circles at the central point: a
separate scale is provided to represent the distance run by the ship which is marked
to correspond with the circles of distance.
I reserve to myself the rights of using any number of distance circles drawn to
any size or scale.
2nd of using any suitable material in the construction of the instrument.
3rd of using any suitable means of illuminating it for night service.
4th of mounting it on gimbals or otherwise in any suitable case, pedestal or
stand.
5th of using any suitable device for clamping the bearing bars or other adjustable
parts of the instrument.
6th of fitting any suitable sight vanes to facilitate taking bearings.
The instrument is used thus
Take a bearing of an object to which you fix the first bearing line, then the ship
runs her course for any desired distance and another bearing is taken to which the
second bearing line is fixed; then lay the scale parallel to the line of course
on that side of the instrument that is opposite to the object and move it to or
from the centre (keeping it parallel to the said line) until the distance run
just touches the inner edges of the bearing bars, the number of circles from the
centre to the points of intersection will correspond with the distance from the
object when each of the bearings were taken; also the edge of the scale will shew
the distance yet to run to reach the nearest point to the object and the circles will
indicate what that nearest distance will be.
Dated this 11th day of January 1893.
PHILLIPS & LEIGH,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Off-shore Distance Indicators.
I, EDWIN BAKER, of 32, Claude Road, Cardiff, in the County of Glamorgan,
Master Mariner, 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 :—
My invention relates to improvements in off-shore distance indicators and the
object of it is to provide an instrument capable of determining the distance of a

page_text: ship from a given object without mathematical calculation, that is to say, the
instrument which is the subject of the present invention indicates the distance, and
this is read off instead of being worked out mentally.
In carrying it into effect, I provide a base of any suitable material and set out
thereupon a series of concentric and equidistant circles. These are bisected twice
by two diameters drawn at right angles to each other. These bisections form scales
of miles or other convenient units of distance. All the four scales have a common
zero in the centre of the circles. One of the diameters is used as representing the
line of the ship's course and is preferably marked accordingly. The largest circle
is set out with degrees or with the points of the compass or with both. The circular
scale or compass may be on a ring attached to the base but capable of rotation
about it. A pair of bars is pivotted to the centre of the base. Each bar is rather
larger that the largest circle in order that its extremities may travel over the outer
divided circle or the compass. The adjacent or inner edges of these bars, when
touching, coincide with a diameter of the base and therefore form a diametrical
bearing line right across the centre. When the bars are separated their inner
edges form two diametrical bearing lines which bisect each other and the distance
circles above mentioned. A detached straight edge set out with the same scale as
the two above mentioned diameters on the base, is provided for the purpose of
measuring off the distances indicated upon the base by the use of the bars in
conjunction with the distance circles above mentioned.
In order that my invention and the means by which it is be carried into practical
effect, may be thoroughly understood, I will now describe it and them in detail,
referring in so doing to the accompanying figures which are to be taken as part of
this Specification and read therewith."
Fig. 1 is a plan and Figure 2, a transverse sectional elevation through the centre
of the indicator.
a is the base.
It may be a card or a metal plate. The latter is preferable.
, are the two diameters set out at right angles with each other. When the
instrument is used, it is held with one of them coincident with the ship's course and
for that reason, the end of one line-say the darker-is or may be marked
accordingly. d, d are the distance circles. They produce four scales on the
diameters b, c, all radiating at right angles with each other from the centre of
the instrument. are verticals through the intersections of the said diameters
and distance circles, and parallel with one of the former.
e is a ring of a sufficient width to be marked with the points of the compass or
with degrees. It is shown as marked with the former. This ring fits close_up to
the edge of the base a and the faces of each are in the same plane. Proper
provision is made for it to be rotated in the said plane about the centre of the plate
and for the plate and ring being held together in any relative position.
fg are the two bars or bearing pointers. They are of equal length and are both
pivotted upon the centre of the instrument in any convenient way.
The one
illustrated is by crossing them and forming a hole through them which is passed
over the holding screw described further on The ends of the pointers move over
the ring e. f g are the respective inner edges, each one, or both when they are
placed close together, coincident with a diameter of the instrument.
The devices illustrated by which provision is made for the ring e to be
rotated about the centre of the instrument with its face in the plane of the plate a,
and for the plate and ring to be held together in any relative position, are as
follows. e is an annular flange projecting inwardly from the ring e immediately
behind the plate a. is a diametrical strap extending from one side of the ring to
the other. It is prolonged into a tab h' by means of which the instrument can be
suspended. The strap is made fast to the back of the ring e or to its flange el.
is the shank and the head of the holding screw. The shank is passed from
behind through the strap h, a washer, the plate a and the bars f, g. is a milled
clamping head adapted to work on the screw shank i. is a cock adapted to
steady the motion of the ring e.

page_text: The movable ring e is not essential to the utility of the invention. The circle on
which are set out the divisions of the compass may be upon the same plate or card
as the distance circles d.
jis a straight edge distinct and separate from the instrument but intended to be
used with it. This strainght edge is divided with a scale j¹ corresponding with the
scales on the diameters b, c.
es
The instrument is used as follows. If the compass points are on a movable
ring the latter is rotated until its N coincides with the "ship's head" mark on
the diameter. The object in question is then sighted along the inner edge of the
pointer, and after the ship has run a fixed distance, it is sighted again along the
inner edge of the pointer g. Both pointers (and ring e) are then clamped to
the plate. The straight edge ; is then laid down on the plate a of the instrument
on that side of the centre of it opposite to the object, with its scalej parallel with
the diameter b which is the line representing the ship's course, and, moved to or from
the centre, care being taken to keep it parallel with the course line b, until the actual
distance which the ship has run between the two observations-this distance is a
datum in terms of the scale j' just touches the inner edges f¹, gl. The resulting
triangle made by the scale j¹ and the adjacent edges is a replica of the triangle
made by the ship's course and the two sighting lines of the two observations thus :-
i = object.
y =
x =
"
the ship at the time of the first observation.
"
وو
"
second
وو
The following distances can then be read off from the instrument in the terms of
the scale j¹.
i
=
the distance of the ship from the object at the time of the first observation.
i = the distance of the ship from the object at the time of the second
observation.
y w = the course of the ship.
y = the distance run between the two observations.
1 x = the distance at which the ship will, provided she keeps on the same course,
have the object on her beam.
x = = the distance to be run before the object is on the beam.
The instrument can be used to give the following further indications.
To indicate the distance the ship will be from the object on any bearing.
To indicate how much it will be necessary to alter the course to pass at any
required distance off when abeam, or any particular bearing. Keep the scale
intersecting the second bearing line iz at the point and move the forward end w
the necessary amount farther off from or nearer to the centre i. Then place the
edge of the other pointer f parallel with the scale j' and the reading on the
circle e will be the alteration.
To indicate how much it will be necessary to alter the course when on any
particular bearing to make straight for a buoy or for a fairway at a known distance
or for any other particular bearing. Use the scale and pointer as directed in the
previous paragraph taking care that the forward end of the scale crosses the bearing
of the buoy from the same object at the proper distance. The parallel pointer will
then indicate the course while the scale will indicate the distance to be run to reach
the buoy or the fairway, as the case may be.
To indicate the distance from two objects by taking cross bearings.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed,. I declare that what I
claim is :-
1. The combination with a base, of distance circles concentric about a given
centre, an outer circle divided into degrees or with the points of the compass or
with both, a pair of diameters bisecting each other in the said centre and a pair of
bearing pointers pivotted independently of each other upon the said centre, as set
forth,

page_text: 2. The combination with a base marked with distance circles concentric about a
given centre, of an outer circle divided into degrees or with the points of the
compass or with both, a pair of diameters bisecting each other in the said centre,
lines drawn through the bisections of one of the said diameters by the distance
circles and parallel with the other of them, a pair of bearing pointers pivotted
independently of each other upon the said centre and a detached scale corresponding
with that produced by the above mentioned intersections of a diameter, as set
forth.
3. The combination with a base marked with distance circles concentric about a
given centre, of an outer circle divided into degrees or with the points of the
compass or with both, a pair of diameters bisecting each other in the said centre,
lines drawn through the bisections of one of the said diameters by the distance
circles and parallel with the other of them, a pair of bearing pointers pivotted
independently of each other upon the said centre, a detached scale corresponding
with that produced by the above mentioned intersections of a diameter, a device by
which the said outer circle shall be movable about the said centre in the plane of
the distance circles and a dévice by which all the said movable parts can be held
fast together, as set forth.
4. An "offshore" distance indicator on which the triangle having for its apex
the object in question; for its base, the distance run; and for its sides, the two
bearing lines from the respective ends of such distance upon such object, is indicated
by means of a detached scale and two bearing pointers movable about a common
centre over a compass or a divided circle.
5. An "offshore" distance indicator on which the triangle having for its apex
the object in question; for its base, the distance run; and for its sides the two
bearing lines from the respective ends of such distance upon such object, is indicated
by means of a detached scale, a scaled diameter and two bearing pointers movable
about a common centre over a compass or a divided circle.
PHILLIPS & LEIGH,
22, Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Applicant.