AN IMPROVED MODE OF AND APPARATUS FOR ASCERTAINING THE PROPER COURSE TO STEER SHIPS OR VESSELS
Year: 1860

page_text: LETTERS PATENT to John Barker Berger, of Upper John Street, Fitzroy
Square, in the County of Middlesex, Master Mariner, for the Invention
of "AN IMPROVED MODE OF AND APPARATUS FOR ASCERTAINING THE PROPER
COURSE TO STEER SHIPS OR VESSELS."
Sealed the 10th July 1860, and dated the 18th January 1860.
PROVISIONAL SPECIFICATION left by the said John Barker Berger at
the Office of the Commissioners of Patents, with his Petition, on the
18th January 1860.
I, JOHN BARKER BERGER, of Upper John Street, Fitzroy Square, in the
County of Middlesex, Master Mariner, do hereby declare the nature of the
said Invention for "AN IMPROVED MODE OF AND APPARATUS FOR ASCERTAINING
THE PROPER COURSE TO STEER SHIPS OR VESSELS," to be as follows:-
This Invention of an improved mode of and apparatus for ascertaining
the proper course to steer ships or vessels, relates to an improvement upon
a previous Invention of mine for effecting a similar object, and for which I
lately obtained Provisional Protection. According to the former Invention the.
ship's track from the point or port of departure to the point or port of arrival.
was drawn on a spherical surface in a straight line, by means of a quadrant or

page_text: -arc made to fit the spherical surface, such a line would form an arc of a great
circle of the sphere, and the course to be steered to cause the ship to follow
the track was ascertained by means of a parallel rule, whereby a line parallel
to the track may be formed on a compass card or disc, mounted on the zenith
or pole of the sphere. This compass card or disc was made moveable on its
centre, so as to enable the compass to be turned for the purpose of bringing
the north point opposite to or coincident with the meridian of the ship's place,
but the compass was never removed from the pole or zenith of the sphere;
the parallel rule being employed as before mentioned to ascertain from the
compass the bearing that is parallel with the intended track or course of the ship.
By means of the present Invention I am enabled to dispense with the use
of the parallel rule, and I consequently avoid the risk of error to which the
navigator is exposed in using it. This is effected by bringing the compass
down to the ship's intended track, instead of carrying up to the compass a
line parallel to the ship's track and thereby ascertaining its bearings, as in the
former instance.
In carrying out the Invention on a spherical surface, I construct a metal or
other disc to fit the surface of the sphere, and I mark on such disc the points
of the compass, as in the former instance, and at the centre of the disc I cut
out a hole of any convenient size, and insert therein a piece of horn, talc,
glass, or some other transparent substance, on which I mark the cross lines to
indicate the centre of the compass and the cardinal points, as N. S. E. and W.
In using this contrivance, the meridian of the ship's place is first ascertained
by means of a quadrant of altitude, or other instrument or contrivance adapted
to the pole of the sphere, and a line is drawn on the sphere to indicate that
meridian. The ship's intended track is then drawn, as in the former instance,
and upon placing the compass disc on the ship's place in such a manner that
its N. and S. poles are coincident with the. meridian, and the centre of the
compass is exactly over the ship's place, the true bearings of the track can be
read off from the edge of the compass at that point which, is immediately, over
the track marked on the sphere; although I have hitherto spoken of a spherical
surface as the one to be employed for the purposes of my Invention, and which
is doubtless the most accurate and most to be relied on, I sometimes intend to
lay down a projection on a flat surface. The projection which I prefer to use
for the purpose is that known as the polar projection, or the conical projection
modified may be employed. A curved rule is used to strike on the flat chart
the ship's track, but by modifying the polar projection, a straight rule may be
employed; but the map and the projection of the meridians and parallels of

page_text: latitude to be made suitable for the employment of a straight rule must be con-
siderably distorted, whereas by the employment of a curved rule the whole chart
may be brought to represent with tolerable accuracy a spherical projection.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Barker Berger in the Great Seal Patent Office
on the 18th July 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
BARKER BERGER, of Upper John Street, Fitzroy Square, in the County of
Middlesex, Master Mariner, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighteenth day of January, in the year of our
Lord One thousand eight hundred and sixty, in the twenty-third year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John Barker Berger, Her special license that I, the said John
Barker Berger, my executors, administrators, and assigns, or such others
as I, the said John Barker Berger, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to time
and at all times thereafter during the term therein expressed, should and
lawfully might make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an Inven-
tion for "AN IMPROVED MODE OF AND APPARATUS FOR ASCERTAINING THE PROPER
COURSE TO STEER SHIPS OR VESSELS," upon the condition (amongst others) that
I, the said John Barker Berger, by an instrument in writing under my hand
and seal, should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and cause
the same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Barker Berger, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and by
the following statement, reference being had to the Drawing hereunto annexed,
and to the letters and figures marked thereon (that is to say):-
This Invention of an improved mode of and apparatus for ascertaining the
proper course to steer ships or vessels, relates to a means of effecting this
object by the employment of a moveable compass in combination with a sphero

page_text: face.
or hemisphere, upon which the ship's track from the point or port of departure
to the point or port of arrival may be drawn in a straight line on the spherical
or curved surface means of a quadrant or are made to fit the spherical sur-
Such a line would form an arc of a great circle of the sphere, and the
course to be steered to cause the ship to follow this track may be found on the
moveable compass card or disc, by ascertaining what points of the compass are
coincident with a line which is parallel to the line or course marked on the
spherical surface. The bearings of a ship's course as marked on a chart havo
been heretofore ascertained by means of a parallel rule and a compass placed
at some convenient part of the chart.
In carrying my Invention, I make use of a disc or plate, made, by pre-
ference, of metal, and marked with the points of the mariner's compass, pre-
cisely like an ordinary compass card. This disc plate or card is dish-shaped,
being made to fit the spherical surface on which it is to be used; and at the
centre of the disc I cut out a hole of any convenient size, say, from three-
quarters of an inch to an inch in diameter, and I insert therein a piece of glass,
horn, or other transparent substance, on which I mark cross lines, to indicate
the centre.
By means of this contrivance I am enabled to dispense with the use of the
parallel rule, and I consequently avoid the risk of error to which the navigator
is exposed in using such an instrument. This is effected by bringing the com-
pass disc or plate down to the ship's intended track, instead of carrying up to
the compass by means of a parallel rule a line parallel with the ship's track, as
is now the plan for ascertaining the bearings of the ship's track.
In the accompanying Drawing, Fig. 1, is a plan view of the improved appa-
ratus as seen from above, and which I intend to denominate a sphereometer,
and Fig. 2 is a vertical section of the same. The spherical surface I prefer
to construct of wood, paper, papier mâché, or some other suitable substance
which is capable of holding the well known compositions or preparations on
which marks may be made with either a slate pencil or lead pencil; on
this surface should be marked the lines of latitude and longitude as shewn in
the Drawing. For use on board ship it will be found most convenient that the.
sphereometer should consist simply of a hemisphere as at a, a, in the Drawings
which may be secured on a foundation board b, b. At the zenith or pole a
metal plate c should be inserted, and have a hole made at the centre thereof.
to receive a pin or stud d, whereby a moveable quadrant or arc e, may be
held in its place, but in such a manner that the arc or quadrant may be moved
round in either direction on this pin or stud. The compass f is simply a dish-

page_text: shaped metal or other disc with the points of the compass marked thereon as
before mentioned. This compass is not a fixture but may be placed over any
part of the sphereometer where it may be required. In using the instrument
the meridian of the ships's place is first ascertained by means of the quadrant
of altitude e, or other equivalent instrument or contrivance which is to be
adapted to the pole of the sphere and secured there by means of the pin d, as
shewn in the Drawing, and a line is drawn on the sphere to indicate that
meridian. The arc or quadrante may then be removed from the pole, and
the ship's intended track is then to be drawn on the spherical surface by
means of a pencil, and the curved quadrant or rule, which is of course con-
structed to fit any part of the curved surface of the sphereometer. Upon
placing the compass disc f, on the ship's place in such a manner that its
north and south poles are coincident with the meridian, and the centre of
the compass is exactly over the ship's place, the true bearings of the track
can be read off from the edge of the compass at that point which is imme-
diately over the track marked on the sphere.
The meridian line g, in Fig. 1, may be supposed to be the meridian of the
ship's place at starting, and supposing the ship to have reached the point i,
over which the compass is placed, as shewn in the Drawing, and not to have
deviated from her course, the bearings of that place may be, of course, ascer-
tained in the same manner as at first, that is, the meridian of that place must
be drawn on the sphere as before, as at h, and then, upon placing the compass
thereon with the north and south line of the compass over the meridian and
the centre of the compass on the ship's place, the new course to be steered will
be seen at a glance. It will, of course, be understood that as the latitude of
the ship's place is constantly varying, the bearings will vary with it, and there-
fore, in order to keep the ship from deviating, recourse should be had to the
sphereometer, at, say, every fifty or sixty miles, and the latitude and longitude
of the ship should be checked by observation in the usual way, to see if the
ship has deviated from the proper course, and should any deviation have taken
place a new course must be marked on the sphereometer and the truo bearings
taken therefrom.
Having now described my Invention of "An Improved Mode of and Appa-
ratus for Ascertaining the Proper Course to Steer Ships or Vessels, and
having explained the manner of carrying the same into effect, I claim as the
Invention secured to me by Letters Patent as aforesaid, ascertaining the
proper course for steering a ship by means of a moveable compass applied to
a spherical surface in the manner above set forth.

page_text: And second, I claim the apparatus above shewn and described, whereby
such object can be effected.
In witness whereof, I, the said John Barker Berger, have hereunto set
my hand and seal, the Second day of July, in the year of our Lord,
One thousand eight hundred and sixty.
Witness,
C. WINTERSGILL,
66, Chancery Lane.
JOHN BARKER BERGER. (L.S.)