Year: 1897

page_text: Date of Application, 6th Feb., 1897
Complete Specification Left, 5th Nov., 1897-Accepted, 24th Dec., 1897
〃
I, THOMAS ENGLISH of Hawley near Dartford, Kent, Lieutenant Colonel do hereby
declare the nature of this invention to be as follows:-
A revolving ring is furnished with sight vanes attached to it on one of its diameters,
and also with a pen or pencil or pointer adapted to make marks near the circumfer-
ence of a circular or semicircular protractor, round the centre of which the ring can
revolve. The protractor oan, when required, be fixed in position relatively to the
ship, whilst observations of the horizontal angles subtended between any objects are
being made through the sight vanes on the revolving ring, and these angles can be
indicated on the protractor by marks made by the pen or pencil or pointer. The
protractor can then be removed for the purpose of transferring to a chart the angles
indicated.
1, THOMAS ENGLISH, of Hawley, near Dartford, in the County of Kent, Lieutenant
Colonel, 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 :-
This invention consists essentially of a revoluble ring furnished with sight vanes
attached to it on one of its diameters; a rectangular or circular or a pair of rect-
angular or semi-circular protractors, a pen or pencil or pointer adapted to make marks
on the limbs of any of these protractors and a guide or guides for the pen or pencil or
pointer for ensuring the marking of the protractor accurately on its line of intersection
with the plane passing through the sight vanes. The protractor can, when required,
be fixed in position relatively to the ship whilst observations of the horizontal angles
subtended between any objects are being made through the sight vanes on their
revoluble ring, and these angles can be registered on the protractor by marks made by
the pen or pencil or pointer. The protractor can be removed for the purpose of
transferring to a chart the angles indicated.
In the accompanying two sheets of illustrative drawings-
Fig. 1 is a plan, Fig. 2 an elevation, and Fig. 3 a vertical section of a nautical course
and position finder constructed according to this invention.
Figs. 4 and 5 are elevation and plan respectively of a pin for guiding and securing
the protractor in position on a chart-and

page_text: Figs. 6 and 7 are diagrams illustrating the method of using the instrument.
A base plate a made taper in plan so as to be capable of being accurately fixed in
position, relatively to the ship, between horizontal guides b conveniently placed to
allow observations of horizontal angles subtended between surrounding objects to be
taken, the centre line A A of the instrument during these observations being parallel
to that of the keel of the ship. A circular metallio ring c is secured to the base a and
forms a pivot on which a ring d can revolve. Sight vanese are attached to the ring d
at each extremity of its diameter and binged at f to permit of their being folded down
when the instrument is not in use. Two semi-circular protractors g are held in
position on the base plate a by means of two raised projections h standing up from it.
These projections are shaped and placed so as to hold the protractors with their centres
coinciding with the centre of the ring o and revoluble ring d and their straight edges
parallel to the keel line, and are thumb notched at i so as to allow of the protractors
being readily removed.
The arrangement for guiding a pen or pencil or pointer consists of a pair of
Liorizontal parallel wires secured to the ring d, on the same diameter as the sight
vanes 6, and at such a distance apart as to guide the point of an ordinary black lead
or crayon pencil or other marking instrument so that it will mark either protractor
radially in the direction of the line of sight. Finger studs m n are secured in the
base plate a and ring d to facilitate the manipulation of the instrument.
By means of this invention the course of a ship is found in the following manner.
1. Draw pencil lines from the positions of two known objects on the chart, in pro-
longation of the line joining them; or, if leeway or a cross current has to be allowed
for, draw these lines from each position in the saine direction relatively to the line
joining the objects, as that in which the estimated actual course is, relatively to the
line of the keel. Fix the pins (Figs. 4 and 5) which are conveniently numbered
1 and 2, at the positions of the objects in the order in which it is intended to observe
them.
2. Place the instrument between guides on deck with the straight edges of the
protractors parallel to the keel line. Raise the sights, and align them upon the
object corresponding to pin No. 1. Mark the direction of the sight line upon
the limb of the protractor numbered 1, by using a crayon or black lead pencil held
between the parallel wires of the instrument. Sight the object corresponding to pin
No. 2 and make a similar.mark on the limb of the protractor numbered 2.
3. Remove the protractors from the instrument, and lay them on the chart so that
the centre notch of protractor 1 is at pin 2, and the centre notch of protractor 2 is at
pin 1; whilst the pencil mark on the limb of each protractor coincides with the
pencil line previously drawn from each respective pin. Then the intersection of the
straight edges of the protractors, produced if necessary, will be a point in the ship's
course.
4. Either the course by compass, after correction for leeway and current if
necessary, may be drawn through this point, or the observations may be repeated
after an interval, another point being thus found in the course, which can then be
drawn through the two points.
The ship's position, at the time of observation, may be found by laying either
protractor on the chart, with its centre notch at the correspondingly numbered pin,
and its straight edge parallel to the keel line. A line drawn from the pin in the
direction of the pencil mark on the limb of the protractor, will intersect the course
at the position of the ship.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I clain is:-
-
1. A nautical course and position finder comprising a revoluble ring furnished with
Bight vanes attached to it on one of its diameters, one or a pair of removable pro-
tractors capable of being fixed in position relatively to a supporting base so that the
centre of each is coincident with the centre of rotation of the revoluble ring, and a

page_text: diametrical marker guide secured to the said revoluble ring substantially as
described.
2. In a nautical course and position finder the combination of a fixed pivot ring or
spindle mounted on a base plate, a ring capable of revolving around the said pivot
ring or spindle and furnished with sight vanes attached to it on one of its diameters,
a removable protractor or protractors capable of being fixed in position relatively to
the supporting base plate, and a diametrical marker guide secured to the said
revoluble ring, substantially as set forth.
3. A nautical course and position finder arranged and constructed substantially as
described and shown.
Dated this 4th day of November 1897.
WHEATLEY & MACKENZIE
40 Chancery Lane London W.C. Agents.