Year: 1887

page_text: Date of Application, 5th May, 1887
Complete Left, 3rd Feb., 1888
Complete Accepted, 9th Mar., 1888
We, JOHN GRICE STATTER, and SYDNEY LINTON BRUNTON, both of Alliance
Engineering Works, West Drayton, in the county of Middlesex, Electrical
Engineers, do hereby declare the nature of this invention to be as follows:-
Our invention has reference to certain improvements in holophotal projectors of the
catoptric type.
In such projectors an adjustment is usually provided for the electric lamp in a direction
parallel to the principal axis of the mirror for the purpose of putting the are at the
principal focus of the said mirror.
In a projector having a reflecting mirror twenty inches in diameter and of seventeen
inches focal length such adjustments have not in projectors as at present constructed a
greater range than about four inches and their sole use has been to correct construc-
tional errors in order to place the arc at the principal focus of the mirror.
According to our invention we provide for a great variation of distance between the
surface of the mirror and the arc either by increasing the length of the present adjust-
ment and employing instead of the slow moving adjustment at present used a quick
adjustment such as a rack and pinion or by fixing the lamp rigidly and providing an
adjustment for the mirror in a direction parallel to its principal axis. In either
case the range of the adjustment is twice to four times as great as that at present
employed.
By means of our improved adjustment we can bring the arc (that is the source of
light) within the principal focus, of the mirror and sufficiently near to the surface of
the mirror to cause the projected beam of light to be a very divergent one and also to
be able when necessary to rapidly focus the lamp and project a parallel beam.
To support the mirror we employ clamping clips of metal padded with wash leather,
asbestos, or other suitable soft material, attached to a metal ring of smaller diameter
than the mirror.
The metal ring is carried by spiral springs in tension within a second metal ring
of larger diameter and this second ring is rigidly fixed to the barrel of the projector
in the case where the lamp is moved, and to suitable slides where the mirror is adjusted

page_text: the lamp being stationary the end plate of the arc lamp can pass under the lower edge
of the mirror and does not prevent the approximation of the arc and the mirror. The
springs guard the mirror from fracture by shocks.
The usefulness of our invention will be illustrated by mentioning the following cases
where it is desirable to alter the character of the beam of light projected rapidly or
gradually, at will.
First when it is desired to throw a beam of light upon an object at a distance whose
exact bearings are not known, a projector constructed according to our invention can
be used to throw first of all a divergent beam covering a large field of view, and, as
soon as the object is seen, can be rapidly focussed upon it.
Secondly in approaching an object of considerable size, as in the case of vessel one
carrying a projector constructed according to our invention approaching another vessel,
and wishing to illuminate the whole of its deck; the divergency of the beam thrown
out by the projector can be gradually increased so that its field shall always be
sufficiently large.
The projector when set to throw a very divergent beam can be used for general
purposes of illumination, for example, on board ship for coaling, loading, and
unloading, &c.
G. F.. REDFERN,
4, South Street, Finsbury, London,
Agent for the Applicants.

page_text: Our invention has reference to certain improvements in holophotal projectors of the
catoptric type.
In such projectors an adjustment is usually provided for the electric lamp in a direction
parallel to the principal axis of the mirror for the purpose of putting the arc at the
principal focus of the said mirror.
In a projector having a reflecting mirror twenty inches in diameter and of seventeen
inches focal length such adjustments have not in projectors as at present constructed
a greater range than about four inches and their sole use has been to correct construc-
tional errors in order to place the arc at the principal focus of the mirror.
According to our invention we provide for a great variation of distance between the
surface of the mirror and the are either by increasing the length of the present
adjustment and employing instead of the slow moving adjustment at present used a
quick adjustment such as a rack and pinion or by fixing the lamp rigidly and providing
an adjustment for the mirror in a direction parallel to its principal axis. In either
case the range of the adjustment is twice to four times as great as that at present
employed.
By means of our improved adjustment we can bring the arc (that is the source of
light) within the principal focus of the mirror and sufficiently near to the surface
of the mirror to cause the projected beam of light to be a very divergent one and
also to be able when necessary to rapidly focus the lamp and project a parallel
beam.
To support the mirror we employ clamping clips of metal padded with wash leather,
asbestos, or other suitable soft material, attached to a metal ring of smaller diameter
than the mirror.
The metal ring is carried by spiral springs in tension within a second metal ring of
larger diameter and this second ring is rigidly fixed to the barrel of the projector in the
case where the lamp is moved, and to suitable slides' where the mirror is adjusted the
lamp being stationary the end plate of the arc lamp can pass under the lower edge of the
mirror and does not prevent the approximation of the arc and the mirror. The springs
guard the mirror from fracture by shocks.

page_text: In order to enable our invention to be fully understood we will proceed to describe
how it can be carried into practice by reference to the accompanying drawings,
in which
Figure 1 is a side elevation partly in section of a holophotal projector constructed
according to our invention, the lamp being adjustable and the mirror fixed;
the stand, the trunnions and other parts not relating to the invention are not
shown.
Figure 2 is a front elevation partly in section of the same.
Figure 3 is a side elevation of part of the projector, showing the hand wheel herein-
after referred to.
Figure 4 is an elevation showing the arrangement for supporting the mirror.
Figure 5 is an elevation of part of a modification of the arrangement shown in
figure 4.
Figures 6 and 7 are vertical sections of the arrangements shown in figures 4 and 5
respectively the sections being taken on a vertical line passing through the centre of
the mirror.
Figure 8 shows the projector set by means of this invention to give forth a parallel
beam of light.
Figure 9 shows the projector set by means of this invention to give forth a divergent
bean of light.
Figures 10, 12 and 14 are longitudinal sections of our holophotal projectors
illustrating the arrangements we employ when the mirror is moveable and the lamp is
n fixture.
Figure 11 is a front elevation of the projector shown in figure 10.
Figure 13 is a cross section showing a detail of the arrangement illustrated by
figure 12.
Figure 15 is a plan of figure 14.
Similar letters in all the figures indicate similar or corresponding parts.
In all the figures of the drawings only such parts as are necessary to explain the
nature of the invention are shown.
We will first describe our invention by reference to figures 1 to 3 and figures 8
and 9 of the drawings.
A, figures 1 and 2 is the electric arc lamp which in this case is a hand-fed lamp but
an automatic lamp can if required be used instead. B is the arc which is the
source of light and is hereinafter referred to as "the arc." C is the usual parabolic
mirror.
The lamp A is mounted in slides D and is capable of being moved quickly in the
direction of the axis of the mirror by the rack È and pinion F which pinion is actuated
by the hand-wheel G shown in figures 2 and 3.
In figure 1 the arc is represented at the principal focus of the mirror C. In this
position a mark or line on the hand wheel G comes under the pointer K (figures 2
and 3) in order that the operator may readily see when the lamp is in the proper
position when the projector is required to give a parallel beam.
The optical conditions are shown in figure 8 which illustrates a projector giving forth
a parallel beam the rays being represented by dotted lines H.
By turning the hand-wheel G (figures 2 and 3) the lamp A and are B can be
carried nearer to the mirror C so that the source of light B is within the principal
focus which has the effect of making the beam of light given out by the projector a
divergent one and as the arc B is brought nearer to the mirror C, so will the divergency
increase according to a well known optical law. The extent to which the divergency
can be carried is limited by the shape of the barrel of the projector and by the danger
of heating and cracking the mirror by bringing the are too close to it.
A very divergent beam with a corresponding position of lamp and are is
represented at figure 9 the rays being represented by the dotted lines H.
In figures 10 and 11 the mirror C is of the usual kind but according to our invention
we support it in such a mannar that it can be rapidly moved backwards and forwards
in the direction of its own axis with respect to the arc-so that the arc can be at the

page_text: principal focus, when it is desired to send a parallel beam, or within the principal
focus when it is desired to send forth a divergent beam.
In this and in the arrangements hereinafter described the lamp and are remain
fixed with respect to the barrel of the projector.
The mirror figure 10 is fixed as hereinafter described within the metal ring M
running within the barrel of the projector on three carriages 0, 0, 0, figures 10
and 11; the ring M is provided with several spokes terminating in a boss or hub P,
which boss receives the end of the quick threaded screw Q. This screw Qcan turn
within the boss P but has little or no end play. It will be seen by reference to figure 10,
that by turning the screw Q by means of the hand wheel G', the mirror & can be
moved in the direction required.
Figure 12 shows a modification of the arrangement shown in figure 10. In this
modified arrangement the screw Q works in bearings at both of its ends and the boss P
has a female thread fitting the screw Q; the ring M has only one carriage which is
in this case only required to prevent the mirror from turning round. The screw Q
passes through a circular hole in the mirror and is supported at the end farthest from
the hand-wheel by the stay R shown in figures 12 and 13.
On rotating the wheel G¹ the boss P is carried forwards or backwards and with it
the ring M and mirror C.
Figures 14 and 15 illustrate an arrangement similar to that shown in figure 10,
excepting that the screw Q is replaced by a plain bar Q₁ capable of being moved
backwards and forwards by a handle G. Springs V and V' serve to lessen the
shock to the mirror which would be caused by a sudden movement of the handle Gi
to its full extent. A set screw Z is provided to hold the bar Q₁ in any required
position.
Figures 4, 5, 6 and 7 illustrate the arrangement we employ for supporting the
mirror C in order to prevent its fracture by shocks.
ring L
The mirror C as shown in figure 6 is held by padded metal clips J fixed to a
which ring is held within a second ring M by a number of spiral springs NN in
tension.
The ring M is either fixed rigidly to the barrel of the projector, as shown in figure 1,
or is attached by spokes to the hub or boss P, as shown in figures 10, 12 and 14. The
springs N can act directly in one plane, as shown in figure 6, or at an angle alternately
sloping from either side as shown in figure 7. In this latter case the ring M is made
channel-shaped in cross section, as shown in the said figure 7.
The usefulness of our invention will be illustrated by mentioning the following cases
where it is desirable to alter the character of the beam of light projected rapidly or
gradually at will.
First when it is desired to throw a beam of light upon an object at a distance
whose exact bearings are not known, a projector constructed according to our invention
can be used to throw first of all a divergent beam covering a large field of view, and,
as soon as the object is seen, can be rapidly focussed upon it.
Secondly in approaching an object of considerable size, as in the case of one
vessel carrying a projector constructed according to our invention approaching another
vessel, and wishing to illuminate the whole of its deck, the divergency of the beam
thrown out by the projector can be gradually increased so that its field shall always be
sufficiently large.
The projector when set to throw a very divergent beam can be used for general
purposes of illumination, for example, on board ship for coaling, loading and
unloading, &c.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is :-
1. In holophotal projectors of the catoptric type supporting the mirror upon a frame-
work in a manner such that it can be moved within the barrel of the projector,
substantially as and for the nurnose described

page_text: 2. The arrangements herein described for supporting the mirror by rigidly fixing it
to a metal ring supported by another metal ring by means of spiral springs in tension,
substantially as and for the purpose hereinbefore described and illustrated in figures 4,
5, 6 and 7 of the accompanying drawings.
3. The manufacture and use of the improved holophotal projectors herein before
described and illustrated in the accompanying drawings.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London,
Agents for the Applicants.