Improvements in Eclipsing Screens for Revolving Group-flashing Lighthouse Lights, for Signalling Lights, or the like.
Year: 1899

page_text: Date of Application, 8th Sept., 1899
Complete Specification Left, 9th Jan., 1900-Accepted, 11th Aug., 1900
PROVISIONAL SPECIFICATION.
Improvements in Eclipsing Screens for Revolving Group-flashing
Lighthouse Lights, for Signalling Lights, or the like.
I, ALAN BREBNER, of 4, Nemoure Road, Acton, London, W., in the County. of
Middlesex, Bachelor of Science and Associate Member of the Institution of Civil
Engineers, do hereby declare the nature of this invention to be as follows:-
The main feature of novelty in my invention lies in this that, whereas eclipsing.
screens for revolving group-flashing lights hitherto used or proposed have been so
constructed as to eclipse the whole of the light-source at once whether by their sole
action or by their action combined with that of reflectors, I propose a subdivided
form of screen whereby it becomes possible to cut off only a fraction such as ½, 1, 4.
or &c. of the light-source at one time and by means of which it becomes possible to
obtain groups of flashes of a suitable duration in a more compact sequence or with;
shorter periods of eclipse than it is possible to obtain with eclipsing screens, which,
alone or in combination with a reflector cut out all the light simultaneously.
5.1
In illustration of the advantage to be derived from a subdivided eclipsing screen
Figs. 1 and 2 may be consulted. Fig. 1A represents in horizontal focal section and
Fig. 1B in vertical focal section a single-beam revolving light consisting of a lens LLL,
reflector RRR, luminary B and eclipsing screen S.
Fig. 2 represents in horizontal focal section and Fig. 2, in vertical focal section a,
double-beam revolving light consisting of lenses L₁LL and LLL, luminary B and
a subdivided screen in two parts S, and S.
In Fig. 1A D stands for the meau divergence of the beam from lens LLL, whilst in
Fig. 2 D, and D₂ stand for the mean divergencies of the beams from lenses LL, L
and LaLaLa
1
The luminaries B are similar and equal in size in both cases and lenses L, L₁ and La
are likewise similar and equal to one another.
Suppose the characteristic required to be a double-flashing light and that the
duration of flash must be 1 second.
The luminaries and lenses of Figs. 1 and 2 being equal it follows that the apparatus
of either must revolve at the same speed, which may be supposed to be one
revolution in five seconds. For the satisfactory working of these eclipsing lights in a
lighthouse it is necessary that there should be a dark horizontal are or an arc
throughout which it is unnecessary to maintain the character of the light, and in this
are the opening and closing of the screens must be effected.
Now in Figs. 1 the apparatus is allowed to revolve twice with the screen S raised
and then the screen is dropped whilst the beam is in the dark are only to be raised
again after two revolutions of the apparatus and so on continuously; there results for
the observing mariner a light showing
:

page_text: the whole double-flashing characteristic being presented in each successive period of
20 seconds.
In Figs. 2 on the other hand the apparatus starts with S, closed in front of lens L.,
and screen S₁ raised whilst beam D, is over the dark arc referred to above; screen S₁
continues raised during one revolution then lowered during one revolution and so on
continuously; when lens L₂ and screen S₂ have come to the position in the dark are
from which lens L, started screen S, is raised and remains raised during one revolution
and then is lowered during one revolution and so on.
There results a light showing
Comparison of the alternative designs of Figs. 1 and Figs. 2 shows that that of
Figs. 1 gives flashes about 30 per cent. more powerful than that of Figs. 2, whilst the
latter design has the advantage of completing the double-flash signal in half the time,
or of giving this signal twice in the time required for one delivery of it by design of
Figs. 1.
Similarly if a triple-flash signal be required the combination of Figs. 2 delivers it
in 12 seconds instead of 25 seconds required for the delivery of it by combination
of Figs. 1 and so on for other group-flash characteristics.
Another advantage combination of Figs. 2 has over combination of Figs. 1 is that
by means of it the relative intervals of flash laid down as a maximum in the light-
ning-light system by the French State engineers can be realized without using lamps
of exceptional size producing excessive heat.
If again the apparatus be of 3 panels each subtending about 120° in azimuth and
a subdivided screen in 3 parts be used, a still more compact set of group-flashing
signals can be obtained albeit with reduced power of beam in each flash." And in
this case there is a set-off against reduced power of light in the fact that the 3-panel
apparatus can be worked in a smaller and cheaper lantern.
The subdivided screen may also be used with advantage in certain combinations of
apparatus giving flashes of equal power but of different colour or duration which need
not be gone into in detail.
One characteristic of my proposed subdivided eclipsing screens is that they must
necessarily revolve along with the optical panels from which they are adapted to
intercept the light proceeding towards them from the luminary. The simplest
direction of displacement of these screens in operation is a vertical one, but any less
convenient mode of causing them to alternately intercept and liberate the rays
proceeding towards the revolving optical panels, as for instance the rotation of the
subdivisions of the screen in a horizontal direction round pivots midway between the
closed and open positions of these subdivisions, is claimed as included in my
invention.
Other characteristics of my proposed subdivided screens are that when all the
subdivisions are closed the light of the luminary is intercepted towards all points of
the compass, that the minimum number of optical panels they are to be used with is
two, and that each subdivision has a panel of optical apparatus corresponding to it
from which it intermittently intercepts the light and never intercepts the light from
any other panel, so that these subdivided screens, the sum of which forms a complete
screen intercepting when all closed all the light from the central luminary, cannot
be confounded with a partial screen, intercepting only the light from the central
luminary in a limited azimuth, such as might be used in Figs. 1, shown as-Z,
whether of cylindrical, spherical or other form, placed hetween luminary and reflector
at one time and brought round between luminary and lens at another time; for such

page_text: latter partial screen could not at all be used so as to provide a more compact sequence
of group flashes such as ny subdivided screen is specially designed to produce..
Another characteristic of my proposed subdivided screen is, that in their best form:
the subdivisions must overlap at the borders, as shown in S, and S, of Figs. 2, in
order that the interception of light from the corresponding panels may be complete,
still the less efficient form of subdivided screen without overlapping borders falls
within my claimed invention.
I claim in short the invention of the subdivided screen used in connection with
revolving group-flashing lighthouse lights, with signalling lights based on the same
principle and the like, whatever be the new combinations obtainable by the use of
such subdivided screen along with revolving optical apparatus.
The mechanism for working the subdivisions of the screen is not shown because it
may be of many different forms; its movement will however be preferably dependent
on and synchronous with that of the optical apparatus and an illustration of one form,
of this mechanism will accompany the complete specification. Similarly the full
details of the screens, their connection with the mechanism and the connection, of
the mechanism with the optical apparatus, which are not shown now, will be illus-
trated in drawings accompanying the complete specification.
Dated this 8th day of September 1899.
Improvements in Eclipsing Screens for Revolving Group-flashing
Lighthouse Lights, for Signalling Lights, or the like.
I, ALAN BREBNER, of 4, Nemoure Road, Acton, London, W., in the County of
Middlesex, Bachelor of Science and Member of the Institution of Civil Engineers,
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:-
SO
1. The main feature of novelty in my invention lies in this, that, whereas
eclipsing screens for revolving group flashing lighthouse lights hitherto used
or proposed have been constructed as to eclipse the whole of the light
whether by their sole action or by their action combined
source at once,
with that of reflectors, I propose a sub-divided form of screen whereby it becomes
possible to cut off only a fraction, such as,,, or the like, of the light source at
one time, and by means of which it becomes possible to obtain groups of flashes of a
suitable duration in a more compact sequence, or with shorter periods of eclipse than
it is possible to obtain with eclipsing screens, which, alone or in combination with a
reflector, cut out all the light simultaneously.
2. In illustration of the advantage to be derived from a sub-divided eclipsing
screen Figs. 1 and 2 may be consulted. Fig. 1 represents in horizontal focal
section, and Fig. 1B in vertical focal section, a single beam revolving light, consisting
This combination is
of a lens L, reflector R, luminary B, and eclipsing screen S.
not included in my invention..
3. Fig. 2 represents in horizontal focal section and Fig. 2B in vertical focal section
a double-beam revolving light, consisting of lenses L₁ and L, luminary B, and a sub-
divided screen in two parts S, and S. This combination is included in my
invention.
4. In Fig. 1A, D stands for the mean divergence of the beam from lens L, whilst,
in Fig. 2, D, and D₂ stand for the mean divergences of the beams from lenses L₁
and L. The luminaries B are similar and equal in size in both cases, and lenses. L,

page_text: azimuth and a sub-divided screen in three parts be used, a still more compact set of
group-flashing signals can be obtained, albeit with reduced power of beam in each
flash.
And in this case there is a set-off against reduced power of light in the fact
that the three-panel apparatus can be worked in a smaller and cheaper lantern. And
in general, where it is more important that the flashes be numerous in a given time
than that they be very powerful, the sub-divided screen becomes invaluable.
13. The sub-divided screen may also be used with advantage in certain combina-
tions of apparatus giving flashes of equal power but of different duration or colour.
14. One characteristic of my proposed sub-divided eclipsing screens is that they
must necessarily revolve along with the optical panels from which they are adapted
to intercept the light proceeding towards them from the luminary. The simplest
direction of displacement of these screens in operation is a vertical one, but any less
convenient mode of causing them to alternately intercept and liberate the rays pro-
ceeding towards the revolving optical panels, as, for instance, the rotation of the sub-
divisions of the screen in a horizontal direction round points midway between the
closed and open positions of these sub-divisions, is claimed as included in my
invention.
15. Other characteristics of my proposed sub-divided screens are, that when all the
sub-divisions are closed the light of the luminary is intercepted towards all points of
the compass, that the minimum number of optical panels they are to be used with is
two, and that each sub-division has a panel of optical apparatus corresponding to it,
from which it intermittently intercepts the light and never intercepts the light from
any other panel, so that these sub-divided screens, the sum of which forms a complete
screen, intercepting when all closed the light from the central luminary towards all.
points of the compass, cannot be confounded with. a partial screen, intercepting only
the light from the central luminary in a limited azimuth, such as might be used in
Figs. 1, shown as Z, whether of cylindrical, spherical or other form, placed between
luminary and reflector at one time and brought round between luminary and lens
at another time; for such latter partial screen could not at all be used so as to provide
a more compact sequence of group-flashes such as my sub-divided screen is specially
designed to produce.
16. Another characteristic of my proposed sub-divided screen is that, in their best
form, the sub-divisions must overlap at the borders, as shown in S, and S₁ of Figs. 2,
in order that the interception of the light from corresponding panels may be com-
plete, still, the less efficient form of sub-divided screen without overlapping borders
falls within my claimed invention.
17. I shall now describe the method of working the sub-divisions of the screen
which I consider the simplest, although it may be convenient sometimes to use any
other suitable method. At the same time I shall describe the details of the sub-
divided screen. For these purposes Figs. 3 to 5 may be consulted.
18. Fig. 3 illustrates in plan, and Fig. 3B in vertical sectional elevation, the sub-
divided screen composed of two sub-divisions, the essential details of these sub-divi-
sions, the mechanism for working them, their connection with the mechanism, and
the connection of screens and mechanism with the optical apparatus: Figs. 4 and 5
show further details of the working mechanism and will be referred to further on.
19. In Figs. 3 and 3B, B is the unique burner placed at the focus of the optical
apparatus, L, part of the frame of one of the two lenses to each of which one semi-
sereen is adapted as indicated in Figs. 2A and 2B; n₁, no, are guide-lugs attached to
semi-screen S₁; na, n₁, guide-lugs attached to semi-screen S₁; 0₁, 0₂, are vertical
guide rods to semi-screen S, as it rises or falls; 03, 04. the same for semi-screen S₂;
91, 92. are stiffening stays to o, and o₂; q, the same to 0, 0₁; F is the support to
lever E, E, is a lever connected at one end to semi-screen S, by a species of piston
rod jointed at either end (it may be with ball or roller bearings), the other end of E,
moving in a slit of cylinder C; E. works in a vertical plane about a fulcrum in F,
with or without ball or roller bearings, and is provided with a counter-weight W, so
adjusted as to balance the two parts of the lever with their adjuncts on opposite sides
of the fulcrum; H is an addition to the frame of the lenses L, and L₂, adapted to

page_text: carry F, and the parts and p₂ to which guide-rods 01, 0, 0, and o₁ are fixed, and
probably also the smoke-tube and damper to burner B; the form of H will vary
according to the form of the optical apparatus to be dealt with; all the parts hitherto
inentioned revolve along with the optical apparatus, excepting possibly, in certain
cases, the burner B and its smoke-tube; C is a cylinder fixed relatively to the
revolving apparatus, whether to the lantern standards A through brackets J, or by
other suitable means; C has cut in it lower and upper horizontal slits ₁ and
placed in communication with each other by diagonal slits 3 and 4, as shown clearly
extends all round
in Fig. 4B and also in Fig. 5, in which latter case the lower slit
the cylinder C; when the outer end of lever E, is engaged in the lower slit ₁, the
screen S, is raised; when engaged in the upper slit the screen S, is lowered, and
the flame behind it eclipsed from the lens 1; in passing from the lower to the upper
slit, the end of lever E, passes along the diagonal slit, the screen S, being lowered
and the light of B shut off from lens ; when it moves back to the lower slit along
54, the screen S, is raised and the light liberated towards lens L₁; as lever E, and
semi-screen S, with their adjuncts correspond to lens 1, so another lever Ea, shown
in part in Fig. 3A, with semi-screen S, and similar adjuncts, correspond to lens
not shown, except roughly in Figs. 2 and 2.
20. As mentioned in Section 6, the opening and closing of the sub-divisions of the
screens must be effected whilst the corresponding beam points over the dark are of
the lighthouse. Consequently, the portions of cylinder C, containing the diagonal
slits and 4, must be fixed to the lantern in such position as will cause the sub-
divisions of the screen to rise or fall whilst the beam points over the dark are.
Figs. 4B and 5B, the azimuthal angle occupied by slits, and 4 is 36°, an angle
generally suitable, but, if necessary, it may be made less or greater when the dark
are of the lighthouse is less or greater.
In
21. Suppose, now, the characteristic required be a double-flashing light, Figs. 4
and 4 show the arrangement of diagonal slits for this case, in which neither of the
horizontal slits 2, nor need be carried all round the cylinder C. At the intersection
of the diagonal slits 2, and, in this, as in all other cases, are placed two locks, k
and capable of pivoting up or down about one pin between two other pins, p, and
P4 in C, so as to open or close the passages along slits 3 and 4. To prevent rattling
each lock is provided with a small spring (not shown) between its shorter end.and
cylinder C, so as to hold it where it is put. Suppose, now, the apparatus, consisting
of the lenses I, and L, starts its revolution, actuated by any of the usual clockwork
machines, with outer end of lever E, at the foot of slit 4 or the beginning of slit s₁,
and outer.end. of lever E., consequently, near the middle of slit on the opposite
side of cylinder C, and continues revolving at the rate of one revolution in five
seconds. As the end of E, moves round, the semi-screen S, is raised, so that a
beam of light from lens I passes round the horizon, and when the outer end of E
comes round to the beginning of ₁, after passing down and raising semi-screen S.,
lens in turn, moves a beam of light round the horizon; when outer end of lever E
comes to slit and passes up it to the beginning of semi-screen S₁ is thereby
closed and remains so till outer end of lever E, has once more revolved with the
apparatus and descended ; similarly, in turn, semi-screen S, makes one revolution
closed before being re-opened as outer end of lever E, descends 24; the light shown
mean horizontal
to the mariner, the burner B. having been chosen so as to produce a
divergence of beam of 74°, is thus as follows:-.

page_text: Witn
he characteristic double flashing group repeating itself every 10 seconds.
egard to locks k, and k, it is evident that k, is free to move out of the way of the
ever-end ascending z, or descending z at any time; k, on the other hand, is dis-
placed by projections on the end of lever E, acting on pinj, each time this lever-end
passes j3, so that as soon as lever-end E, has passed lock kg in one diagonal slit it
closes this lock in this slit and opens the other slit. The projections on outer end of
ever E, do not exist on that of lever E₁, but their form is shown in dotted lines on
lever E, in Fig. 3B.
22. For the production of the other group-flashing characteristics slit z, must be
carried all round cylinder C as shown in Fig. 5B, and two more locks, k, and kд, are
Lock is moved freely at any time into the
required, besides k₁ and k₂ of Figs. 4.
required position by the travelling lever-ends without other aids, just as mentioned
for k; k₁, however, requires a special device for opening or closing diagonal slit zg;
further, lock ką must now be controlled by a special device which need not be
described, since it is analagous to that to be now described for k₁. This device is
illustrated in plan in Fig. 5, and in developed vertical elevation in Fig. 5B. Lock.k₁
moves about pivot m₁, being checked in range by pins p and P; like the other
locks it has a small spring in its shorter end near m₁ which presses enough on
cylinder C to hold the lock where it is put and prevent rattling. At the approach
to the intersection of slit z, with slit z₁ is placed a small toothed wheel w₁ inside
cylinder C on a turning pin, which carries cams y₁ and y, at its other end outside C;
to the right of w₁ are placed two pins m, and m, about which or along with which
turn two levers v₁ and v₁, held up and down respectively by springs x and x, when
not pressed down and up respectively by cams y, and y; in Figs. 5 the pinion w₁
has 5 teeth, and corresponds to a quintuple-flashing light, and the number of teeth
in w, will be in each case the same as the number of flashes in the group-flashing
characteristic. (In some cases cams y, and y, may be one and the same.) Suppose
NOW,
for example, one finds the optical apparatus revolving at the rate of one revolu-
tion in five seconds, driven by the usual weighted clockwork or other suitable means,
and that w, is in the position shown in Fig. 5B, whilst levers E, and E, have their
outer ends engaged in lower siit z₁, and therefore are holding the screens S₁ and S
open whilst the lenses are emitting flashes at 2 seconds intervals; when end of E
comes to w₁ it will move it round one tooth, cam y, acting on lever v₁ and causing
its other end to move k₁ to its lower position, locking z₁ and opening 2, so that end
of E, moves up the latter, lowering semi-screen S, and interrupting flashes from
lens L when end of lever E, arrives in turn at w₁ it moves it round one tooth
farther and passes up 3, closing semi-screen S, and interrupting flashes from lens L₂,
whilst cam y, is left close up to left end of lever v₂; shortly end of lever E₁ arrives
at and descends along z, entering in, with semi-screen S₁ raised and lens L₁
causing flash No. 1 of a new group to move round the horizon; 2 seconds later,
end of lever E, descends 24 and enters z₁ with lens L, carrying flash No. 2 of the
group round the horizon; after nearly 2 seconds more, end of lever E, arrives at
pinion w, and moves it a third tooth round, causing cam 2 to move v₂ and thus
push k, back to its upper position, locking and opening ₁, so that end of lever E₁
continues along z, to produce flash No. 3 of the group; then comes end of lever E.,
moves pinion w₁ a fourth tooth round and continues along ₁ to produce flash No. 4
of the group; lastly, comes end of lever E₁, moving pinion w₁, a fifth tooth round
and continuing along to produce flash. No. 5, the last of the group; w₁, again
occupies its primitive position, and 2 seconds after the passage of end of lever E₁
and
Z1 opens zg
O that of lever E, arrives and moving w, the first tooth round closes slit
to the passage of lever E,, which, ascending z,, closes semi-screen S, and begins the
second interruption of the flashes. As stated already, lock kg will in this case be
used similar to k of Figs. 4, but without the pin j,, and will have its position
regulated in a manner analagous to that described for k₁; thus it has been shown
5 how a quintuple-flashing light is to be be obtained showing-

page_text: the characteristic quintuple-flashing group repeating itself every 17 seconds.
23. Similarly by the modification of pinion w₁ of the analagous pinion at the
inter-section of 3 and 4 and of the corresponding cams and levers only, whilst the
entire optical apparatus, sub-divided screen, levers E, and E, and cylinder C remain
unchanged, the other group-fashing characteristics can be obtained.
24. By further sub-division of the screen into three or more parts adapted to optical
apparatus containing three or more lenses and worked in a manner quite analagous to
that described for the semi-screens with bi-valve lenses, all the group-flashing
characteristics can be obtained with shorter total periods, the quadruple-flash total
period, for instance, being reduced from 15 seconds for the screen of two sub-divisions
to 10 seconds for the screen of three sub-divisions for the same burners, lenses of the
same focal length and the same speed of rotation.
25. By combining with a lens of say 90° horizontal compass another of 270°.
horizontal compass specially arranged to give a coloured flash or a flash of threefold.
duration produced artificially, and adapting respectively to them and sub-divisions
of whole screen, or, by analagous combinations, two other classes of distinctive
characteristics can be obtained.
26. Revolving optical apparatus with the sub-divided screen as defined in section 1
and as alluded to in section 25, can be arranged for signalling by the Morse or similar
codes.
27. Having now particularly described and ascertained the nature of my said Inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
(1.) The employment of a complete sub-divided eclipsing screen of two or more
sub-divisions which can be opened or closed independently of one another, in
combination with a revolving optical apparatus composed of two or more panels each
emitting one beam of light and having one sub-division of the eclipsing screen
adapted to it and to it alone, the complete sub-divided eclipsing screen being such
that when all its sub-divisions are closed it entirely cuts off from the panels of the
optic and towards all points of the compass the light from the unique burner placed
at the common focus.
.
(2) A revolving optical apparatus of two or more panels consisting in part of a
complete sub-divided eclipsing screen, one subdivision of the said eclipsing screen
corresponding to each panel of the said optical apparatus, with the necessary operative
means therefor, for the production of group-flashing lights.