Year: 1899

page_text: Date of Application, 6th May, 1899
Complete Specification Left, 5th Feb., 1900-Accepted, 6th July, 1900
JOHN WILSON GILLIE, Nautical Instrument Maker, The New Quay, North
Shields, Northumberland, do hereby declare the nature of this invention to be
as follows;-
-:
A lens is mounted and suspended so that the axis passing through its centre
in which the principal focus, is situated, lies horizontally.
At a suitable distance from the lens, about equal to its focal length, I place
a small semicircle, the diameter of which is placed uppermost in the horizontal
plane, and at right angles to the axis of the lens aforementioned. This semi-
circle is attached to the mounting carrying the lens, and is preferably of a dark
colour. It is observed through the lens, and its upper edge is used instead of the
real apparent horizon, when the latter may be invisible from fog or other causes.
Dated this Fifth day of May 1899.
JOHN WILSON GILLIE.
JOHN WILSON GILLIE, Nautical Instrument Maker, of the New Quay, North
Shields, in the County of Northumberland, 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:-
The object of my invention is to provide a substitute for the natural horizon
by means of a mechanical contrivance, which will permit of the altitude of a
celestial object being measured on board ship when the natural horizon is invisible
from fog or other cause.
In fully describing my invention I will refer to the accompanying drawings
which form part of the specification & in which similar numerals of reference
indicate similar parts wherever found throughout the drawings.
Fig. 1 is a vertical section through the longer axis of the instrument.
Fig. 2 is a. vertical section through the shorter axis of the instrument.
Fig. 3 is an end view.
In the practice of my invention I take a suitable lens or mirror or combination
of prisms & so mount & suspend it that the principal axis, passing through the
centre of the lens or mirror or combination aforesaid. lies horizontally, or nearly
So. At a suitable distance from the lens about equal to its focal length, I fix
a thread, or semicircular disc with its diameter at right angles to the principal
axis aforesaid, so that wherever seen through the lens, by an observer standing
a short distance away, it appears to occupy the same position relatively to the
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page_text: horizon, owing to its being placed near the focus of parallel rays. I suspend the
whole in such a manner as to overcome the movement caused by the usual rolling
& pitching of the ship, & by keeping the lens or mirror & its mounting & attach-
ment as light as possible, any motion given to it may be quickly quelled.
This I prefer to do in the following manner-I mount a convex lens 1 at one
end of a tapered tube, preferably made of aluminium, at the other end of which is
a semicircle of the same metal, fixed near the principal focus of the lens.
This tube has attached to it, near its middle, two knife edge trunnions 4, 4,
which rest on two supports 9, 9, fixed to the interior of a large outer tube 5, in
such a manner that the horizontal diameter of the semicircle 2 seen through the
lens 1 appears to coincide with the natural horizon. The outer tube 5 as its ends
covered with two lids or bezels 10 10, partly filled with glass, so as to protect the
inner tube carrying the lens from being disturbed by the wind. This outer
tube 5 is weighted with lead & so slung on the two screws or pivots 7, 7, as to
keep the trunnions 4, 4, horizontal. The screws 7, 7, are attached to two
arms 6, 6, which are fastened to a tube 8 made to ship over a vertical rod, which
may be attached as found convenient to the bridge rail or other part of the vessel
on which this contrivance is used.. To the lower side of the inner tube carrying
the lens I attach a blade or fin 3, which is made to dip into oil or other viscous
liquid when required to restrain the oscillations of the tube.
I
The oil or other liquid may be contained in the bottom of the outer tube or in
vessel made for the purpose fixed immediately underneath the blade or fin 3.
I may use other methods for restraining any oscillation in the lens & its mounting.
But 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 horizontal line placed in or near the principal focus of parallel
rays of a lens or similar optical combination as herein before described for use
instead of the natural horizon on board ship when the latter is obscured.
(2) The use of such a horizontal line & lens or similar optical combination as
herein before described in combination with an outer case to protect from the
disturbing influence of the wind for use on board ship when the natural horizon
is obscured.
(3) The use of such a horizontal line & lens or other similar optical combination
as herein before described in combination with an outer case & a blade dipping
in oil or other viscous liquid as herein described.
Dated this 2nd day of Wahmo 1000