An Improved Arrangement of Lenses for Search Light Projectors.
Year: 1895

page_text: Complete Specification Left, 30th Nov., 1895 Accepted; 4th Jan, 1898 *****
PROVISIONAL SPECIFICATION.
An Improved Arrangement of Lenses for Search Light Projectors.
EDWARD JAMES PATERSON, of European Works, Pownall Road, Dalston, in
the County of London, Engineer, and CLAUDE WILLIAM HILL, of European
Works Pownall Road, Dalston, in the County of Londou, Engineer; do hereby
declare the nature of this invention to be as follows:-
This arrangement relates to an improved arrangement of lenses applicable to
search light projectors, whereby a single diverging, or bifurcated beam of light.
may be obtained at pleasure, and is particularly applicable to search light
projectors used for the night navigation of narrow water-ways upon which vessels
pass.in opposite directions. It has been found on the Suez Canal that although >
the ordinary single diverging or fantail.beam is eminently suitable for navigation.
of narrow water-ways, it is not suitable when two vessels are approaching each.
other, as the light from one blinds the eyes of the steersman of the other, besides
leading to errors in the judgment of the distance between the two vessels. At such a
time it has been found desirable to use a bifurcated beam,' which illuminates the
two banks of the canal while leaving the approaching vessels in darkness. It is
at present customary to fit projectors for the navigation of the Suez Canal with
two sets of lenses in separate frames, the one giving a single beam and the other
a bifurcated one. For ordinary navigation the single beam lens is used but when
another vessel is seen to be approaching, it is detached and the bifurcated beam
lens substituted. This forms an expensive and somewhat clumsy arrangement,
and the object of our invention is to provide in its place an arrangement of lenses
mounted in a frame, so disposed that the beam may be instantly changed from
single to bifurcated, or vice versa; simply by the movement of a small handle.
To carry this invention into effect, we provide on the front of the projector a
set of prismatic lenses mounted in a suitable frame. These lenses are of such
section and so placed that the parallel rays of light coming from the mirror at
the back of the projector are split up into two diverging beams, leaving a central
unilluminated space. We provide in addition two similar prismatic lenses-placed:
either behind or in front of the first set of lenses and in such a position that when s
parallel to these, they cause the central space to be illuminated, so that the
projector then gives a single diverged or fantail beam of light. When those
2. lenses are turned at right angles to the 'first set, they produce no effect, so that
the beam becomes bifurcated, as though they had been completely removed.
10
We mount the two additional lenses in a carrying frame, attached to, or cast in
one piece with the frame of the first set of lenses, each lens being mounted on?
pivots, a suitable handle or handles being provided, whereby the attendant may
turn them from one position to the other, so obtaining a single or bifurcated beam
at pleasure.
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page_text: An Improved Arrangement of Lenses for Search Light Projectors.
EDWARD JAMES PATERSON of European Works, Pownall Road, Dalston, in
the County of London, Engineer, and CLAUDE WILLIAM HILL of European
Works, Pownall Road, Dalston, in the County of London, Engineer, 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:
c
This invention relates to an improved arrangement of lenses applicable to search
light projectors whereby either a single diverging or a bifurcated beam of light
may be obtained at pleasure and is particularly applicable to search light projectors
used for the night navigation of narrow waterways upon which vessels pass in
opposite directions.
It has been found on the Suez Canal that although the ordinary single
diverging or fantail beam of light is eminently suitable for navigation of narrow
waterways, it is not suitable when two vessels are approaching each other in.
opposite directions, as the light from one blinds the eyes of the steersman of the
other, besides leading to errors in the judgment of the distance between the two
vessels. At such a time it has been found desirable to, use a bifurcated beam
which illuminates the two banks of the canal while leaving the approaching vessels
in darkness.
:
It is at present customary to fit projectors for the navigation of the Suez Canal
with two sets of lenses: in separate frames, the one giving a single beam and
the other a bifurcated one. For ordinary navigation the single beam léns is used
but when another vessel is seen to be approaching it is detached and the bifurcated
beam lens substituted. This forms an expensive and somewhat clumsy arrangement
and the object of our invention is to provide in its place an arrangement of lenses
mounted in a frame so disposed that the beam may be instantly changed from single
to bifurcated or vice versa simply by the movement of a small handle.
Referring now to the drawings, Figs. 1 and 2 represent diagramatically a
sectional plan of a projector in which A is the arc; B the mirror; C. D. the
lenses; E the, parallel rays of light coming from the mirror, (the usual are plate
for cutting off direct rays being omitted in the fig. for the sake of clearness),
and the diverging rays of light coming from the projector shown approximately
as they appear when viewed from above in a cloudy atmosphere.
Figs. 3 and 4 represent the arrangement which we
lenses. :
we prefer
for carrying the
To carry our invention into effect we mnount on the front of the projector a set
of lenses, C. C. Fig. 1, which we call the main lenses. These lenses' are of prismatic
Beotion shaped to give the required angle of divergence to the parallel rays of light
coming from the mirror and so arranged as to split the rays into two diverging
beams with a central unilluminated space as shewn in Fig. 1.
3
In addition to the main lenses we provide two lenses of similar section D. D.
see Figs. 1 and 2, which we call the supplementary lenses. These leases are mounted
on pivots so that they may be turned parallel with or at right angles to the main
lenses.
1 ..
17
In Fig. 1 the supplementary lenses are shewn at right angles to the main lenses.
In this position each stands in the shadow between two of the main lenses and
they produce no effect upon the beam, the shape of which is the same as though
they were entirely removed.
In Fig. 2 the supplementary leuses are shewn parallel to the main lenses. In
this position cach corrects the divergence of the rays coming from one of the main
lenses so illuminating the central space and giving a complete beam.
'

page_text: We should here remark that owing to the smallness of the scale of the
drawing, the direction of the rays has not been shewn with absolute accuracy
but is merely giveu approximately for the purpose of facilitating our description.
In our Provisional Specification we have stated that the supplementary lenses
may be placed behind or in front of the main lenses. In special cases where it
is not possible to mount the supplementary lenses in front they may be placed
behind, but the arrangement is not so satisfactory as that shewn in the accompanying
drawings Figs. 1, 2, 3 and 4.
For the purpose of carrying the main lenses we provide a gunmetal ring G
of suitable form preferably hinged to the front of the projector; upon this ring
are the brackets H. H. which may be attached to it with screws or cast in one
piece with it. Upon the brackets are mounted the bearings I. I. I. I. which may
be made adjustable as shewn for the purpose of setting the supplementary lenses to
their correct positions.
The pivotted sockets K. K. K. K. work in these bearings and carry the
supplementary lenses D. D. The upper pivots have levers L. L. connected
together by the connecting rod M. Upon one of the levers we mount the
handles N. N. by which it may be turned and the two levers being connected by the
rod M are compelled to turn simultaneously.
The spring O is arranged to press on the under side of the connecting rod M,
by its friction holding the arrangement in whatever position it may be placed.
Suitable stops are provided to prevent the movement being turned too far in
either direction.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what
we claim is ;-
1. The combination of lenses substantially as and for the purpose described.
2. The supplementary lenses constructed and arranged to operate substantially
as described and shewn on the accompanying drawings.
Dated this 29th day of November 1895.
EDWARD J. PATERSON.
CLAUDE W. HILL.