Improvements in the Lighting of Harbours and Navigable Channels.
Year: 1897

page_text: COMPLETE SPECIFICATION.
Improvements in the Lighting of Harbours and Navigable Channels.
I, ERNEST DE VISMES DU BOULAY, of the Cottage, Bembridge, Isle of Wight, in
the County of Hants., Captain, late of the Royal Artillery, 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 relates to an improved method of and means for lighting
harbours and navigable channels with a view to enabling mariners to navigate
such harbours and channels with greater safety.
In the accompanying diagrams, Fig. 1 is a view illustrating one arrangement
applicable for a single light; Fig. 2 being an alternative arrangement. Fig. 3
is a view illustrating the mode of applying my invention in the lighting of two
channels; the lights being duplicated.
In carrying out my invention, a pair of opaque masks or shields a a are arranged
at a suitable distance from the source of light b, an interval c being left between
the masks through which the ray of light is projected.
Outside these masks
are disposed translucent screens d, d¹ of the desired colours. The number of
screens and their colours may vary according to requirements. In the examples
illustrated, it may be assumed that d represents a blue screen and a red screen;
a space being left between the two which may or may not be occupied by clear
uncoloured glass. Thus a beam of white light will be projected between two
coloured beams; the white light indicating the 'fair-way' of the channel.
The masks and the screens should be so arranged as to permit of sharply defined
rays or channels of light of any desired width being thrown in any required
direction. By the use of my invention, the narrowest ray from the source of
light is not throttled, but possesses the full illuminating power, owing to the space
or gap between the screens being never less than the rectangle of illumination of
the dioptric lens. By employing one or more sources of light, with or without
reflectors, the intensity and breadth of the light-channels, as also their number,
may be varied; the sides of the channels being paralled diverging or converging.
The colour demarcations are moreover quickly formed, not blending gradually,
but changing suddenly.
In Fig. 3, I have shown my improved method as applied to the lighting of a
channel. Two sources of light 6° 6* are employed at the bend, the screens being
arranged in such a manner that two channels or lanes of light are projected for
the purpose of indicating the fair-way; the helmsman being assured of his safety
so long as the two lights seen a-head remain white. Should the vessel however
deviate from the fair-way, the helmsman will immediately become conizant thereof
by reason of one of the lights appearing to change colour. The relative positions
of the white and coloured lights assists him moreover in recovering the fair-way.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I claim:-
-
1. The herein described method of lighting harbours and navigable channels,

page_text: whereby the fair-way is indicated by a sharply defined ray or channel of light
of full power projected between two coloured rays one on either side.
2. The improved means for lighting harbours and navigable channels, sub-
stantially as herein described, and comprising opaque masks arranged at a suitable
distance from the source of light and translucent screens disposed outside the
said masks, an opening being left between the masks as also one between the
screens, so that a channel or lane of white light of unimpaired power is rendered
visible and serves to indicate the fair-way.
3. For lighting navigable channels and the like and indicating the fair-way,
the employment of two or more sources of light in conjunction with masks and
screens, arranged substantially as herein described.