Improvements in Photographic Shutters.
Year: 1899

page_text: Improvements in Photographic Shutters.
I, JOHN EDWARD THORNTON, of Rokeby, Oldfield Road, Altrincham, Cheshire,
Manufacturer, do hereby declare the nature of this invention to be as follows:―
This invention relates to photographic roller blind shutters, and the means
for operating and controlling the period of exposure in such shutters, but more
especially to that type in which the lens is not uncovered during the act of
setting the shutter for an exposure. This type of shutter is known by various
names, such as for instance, Everset, Safety, or Self-capping.
In carrying out this invention I use a roller blind which moves across the lens
in one direction for one exposure and back in the opposite direction for the
next exposure, or else a blind which moves first in one direction across the lens
and then reverses and returns to its original position to effect the complete
exposure. With either arrangement of blind the lens is never uncovered except
for the exposure.
or
Such a blind may be an endless one having two perforations, and passing
around or over one or more rollers; or it may be a single blind, having one per-
foration, and attached to two rollers at opposite ends of the enclosing case;
it may be a double blind, obtained by using a longer single blind, attached to
two rollers placed at one end of the case, and passing in its travel over one or
more additional rollers at the opposite end of the case, said blind having two
perforations.
In all cases where a single blind is used (as distinct from an endless one) the
two rollers to which the ends of the single blind are secured are so connected that
the rollers and the blind all move in unison. This may be effected in any
suitable way, for instance by using connecting tapes, cords, chains, or the like,
which may pass over sprocket pulleys or may make several turns round each
roller, giving the practical equivalent of an endless blind. If preferred this
method may be dispensed with and some form of gearing used instead to connect
the rollers though prefer the means described.
Whatever arrangement is adopted the point to be observed is that a movement
of one of the rollers in either direction shall cause a similar movement of the
blind, and the action is such that the blind, is given a reciprocating motion.
Movement is given to the blind and rollers by means of a coiled driving
spring, which may either be placed in the barrel of one of the rollers, or
in a separate barrel attached to the shutter, in which latter case the barrel
may communicate rotary motion to one of the rollers by gearing of any
suitable character, or by passing the aforesaid cord or tape (connected with the
blind and rollers) around either the barrel itself or a pulley connected therewith.
My invention comprises the combination of a blind arranged in any of the ways

page_text: aforesaid, and having a reciprocating action such as described, with a regulatable
timing device for interrupting the exposure movement of such blind and for
detaining it for the desired period of time (say for example 500 of a second or
5 seconds) which timing device forms a part of the shutter itself (not part of a
ball and tube releasing device), and the said timing device consisting of one or
more reservoirs, such as a bellows, cylinder, or other suitable arrangement,
containing air, water, glycerine, or other convenient fluid. Such a combina-
tion has not to my knowledge been effected before and is therefore new.
A shutter made according to this invention comprises the following elements:
(1) A blind of any of the forms hereinbefore described, and suitably connected
with one or more rollers; means for connecting such rollers and blind so that all
may work in unison; a driving spring or springs for operating one of such
rollers, directly or through suitable gearing, in such a manner as to control the
movement of the blind; and means for winding up the driving spring, and for
adjusting the tension thereof.
(2) A fluid or air operated timing device for regulating the time of exposure
by interrupting the spring driven blind during its exposure travel, in such a
manner that perforation or perforations in the blind are detained coincident with
the openings in the shutter frame, for a predetermined period of time which can
be altered by the operator setting the timing device accordingly.
(3) A release for setting in action the shutter blind or else the timing device
or both, such as a pneumatic ball and tube, a cord, a trigger, or other convenient
arrangement.
(4) A suitable frame or case to carry the whole working parts in correct
position in relation to each other.
It will be obvious that various modifications in the details of these component
parts or elements are possible without departing from the features of the inven-
tion, which consists of a reciprocating biind such as described, and means for
operating and controlling same. For instance in cases where a very cheap
form of shutter is required I may omit the air or fluid timing device, and instead
obtain a variation in the duration of the exposures by adjusting the tension of
the driving spring alone. Then again the methods possible for giving the roller
and blind a reciprocating motion are numerous. For instance a simple device is
that of a crank (rotated by a driving spring enclosed in a barrel) connected to
a rod having teeth cut on the other end which gear with a pinion on the roller.
Or such a rod might be hooked on to or otherwise connected to the blind itself.
The method I prefer, however, is to use a driving disc, wheel, or segment of a
wheel, which turns freely upon a centre and has teeth upon its edge that gear
with a pinion upon the roller. This disc carries a pin near its edge, on to which
a long and closely wound spiral spring is firmly secured, either to a fixed pin or
to one that can be moved so as to stretch the spring more or less. When the
spring is hooked on to the driving disc, it is only held from rotating by the
detent controlled by the releasing device or mechanism. As soon, however, as
the detent is removed, the disc makes about half a revolution, turning the rollers
and blind at the same time, thus making the exposure.
For the next exposure the pin that connects the driving spring with the disc
is moved over to the opposite side of the centre, thereby placing the pull of the
spring in the opposite direction. The result is that, upon removal of the detent,
the rollers and blind turn in the opposite direction, thus giving another exposure.
The spring may be placed in engagement with the pin on the driving disc by a
pair of claws or hooked levers attached to the spring: these readily connect on
to the pin upon the return stroke of an operating piece which is used to set the
shutter, and which may also act as the release trigger if the automatic timing
device is not used.
The form of timing device which I prefer to adopt consists of a closed bellows
divided by a diaphragm into two compartments, and having a port or valve com-
municating with the two so as to allow the contents to pass from one to the other.

page_text: The bellows is charged with water, but glycerine, air or other fluid may be
used instead, and only sufficient necessary to fill one compartment at a time.
A spiral spring or equivalent presses on the bellows in such a way as to compress
that part of it which is filled with the fluid, with the result that the fluid is
slowly forced into the other compartments thus allowing the first one to gradually
empty and that part of the bellows to close. The whole bellows is preferably
enclosed in a vulcanite, metal, or other case to protect it, and as the bellows.
moves the outer case moves also. This movement is utilized to control the period
during which the moving blind shall be detained in a position of rest. One part
of the bellows or case may be so connected to the shutter (by a cord, band, rod,
or other means) that it shall be moved, when winding up or setting the shutter
for exposure, in such a manner as to compress one chamber against the spring,
and so force the fluid into the other chamber, in which position the bellows is
held by a suitable detent until required. As soon as it is released again by the
operator to make the exposure the fluid escapes slowly into the other chamber,
owing to the compression of the spring. Or the same result may be obtained by
omitting the spring, though the movement is then slower and less certain.
Although I use a bellows in this description, it will be obvious that an
equivalent device such as two cylinders fitting closely into each other, or a
cylinder and piston or plunger, would answer the purpose. Such devices are
well known, but, owing to the difficulty of making non-leaking sliding joints
without too much friction in action, I prefer the closed bellows arrangement.
The time of exposure may be varied by varying the rate of travel of the
timing device, say by introducing an adjustable valve or cock between the two
chambers; or instead the timing device may have a constant rate of travel in
which case an adjustable stop would be attached to it instead.
The parts of the shutter are arranged so that, as soon as the timing device is
set in motion, a stop thereon operates the detent which holds the blind against
the pull of the driving spring, thus releasing the blind and so commencing the
exposure. The travel of the blind is arrested by a second detent as soon as the
opening therein is coincident with the opening in the shutter frame or case,
but as soon as the predetermined time of exposure has elapsed the stop on the
timing device moves this second detent and allows the blind to proceed and.
terminate the exposure.
In this way the shutter may be constructed to give a wide range of exposures
with accuracy, say for instance from Toσ of a second to 20 or 30 seconds. An
indicating device, such as a dial and pointer for instance, serves to show the time
of exposure for which the shutter has been set. The timing device on the
shutter is set in motion by any suitable means, such as are well known, for
instance a pneumatic ball and tube, a cord, or a trigger. For longer exposures
than the shutter is capable of being set for, a detent is used which holds the
shutter open until the releasing device is operated a second time, whereupon
the detent moves and the shutter closes.
Gearing or mechanical devices of any suitable form are used to connect the
roller or rollers with the driving spring; and to wind up the shutter for exposure;
and to connect the timing device with the detents that control the blind; and to
permit the blind to travel the proper distance before being stopped.
The case may be of any suitable construction as is well understood, say of
metal, wood, or other material. I prefer to mount all the working parts in or
upon a rectangular skeleton frame, which is afterwards fitted into an enclosing
case that completes the shutter and is finished in any suitable manner.
1000

page_text: Improvements in Photographic Shutters.
I, JOHN EDWARD THORNTON, of Rokeby, Oldfield Road, Altrincham, in the
County of Chester, Manufacturer, 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 photographic roller blind shutters and the means for
operating and controlling the period of exposure in such shutters.
The invention will be fully described with reference to the accompanying
drawings.
Fig. 1. Is a front elevation of shutter with a single blind.
Fig. 2. Is an elevation of one side of same showing the timing device attached
thereto.
Fig. 3. Is an elevation of the other side showing the releasing mechanism for
setting in action the shutter.
Fig. 4. Is a front elevation of the shutter showing a modified arrangement of
the parts.
Fig. 5. Is an elevation of one side of same (Fig. 4) showing timing device.
Fig. 6. Is an elevation of the other side of same (Fig. 4) showing the blind
releasing mechanism.
Fig. 7. Is a side elevation of one form of single blind.
Fig. 8. Is a side elevation of another form of single blind.
Fig. 9. Is a side elevation of another form of single endless blind.
Fig. 10. Sectional detail of liquid timing device.
Fig. 11. Modification of stop rod
and p².
Fig. 12. Is a front elevation of the shutters.
Fig. 13. Is an elevation of one end showing the timing and releasing device.
Fig. 14. Is an elevation of the other end showing the actuating mechanism.
Fig. 15. Is an elevation showing the reverse side of parts of the mechanism
shown in Fig. 14.
Fig. 16. Is a side elevation showing an alternative arrangement of actuating
mechanism.
Fig. 17. Is an elevation of the blind and blind rollers.
Fig. 18. Is a section of same.
Fig. 19. Is a sectional side elevation of another form of blind.
Fig. 20. Is a sectional side elevation of a single blind mounted upon three
rollers.
Fig. 21. Is a sectional elevation of another arrangement of the single blind
passing over three rollers.
Fig. 22. Is another modification of the same.
Fig. 23. Is a side elevation of rack mechanism for gearing two rollers together.
Fig. 24. Is a side elevation of endless chain mechanism for gearing two rollers
together.
Fig. 25. Is a side elevation of quadrant and tooth mechanism for gearing two
rollers together.
:
Fig. 26. Is a side elevation of gearing for connecting the two top rollers shown
in Fig. 20.
The blind A of the shutter is of one of the common or ordinary forms employed
in single blind shutters passing over or around a top roller B and a bottom
roller C actuated by a spring.
The blind A2 may be endless as in Fig. 9 always rotating in one direction as

page_text: indicated by the arrows the exposure taking place at each movement in which
case the lens is not uncovered to re-set the shutter. Or the setting of the blind
for another exposure may be effected by winding it back in the reverse direction
in which case the lens would be uncovered during the operation. In either of
these modifications the blind has two apertures which pass each other in opposite
directions opposite the lens during the travel of the blind.
The blind A as shown in Fig. 8 instead of being endless may roll off the
roller B on to the roller C and from the roller C back to the roller B the two
rollers being also connected together by a cord chain or flexible band b shown
in dotted lines so that all operate in unison. The blind A' is provided with one
aperture and always moves in the direction of the arrow across the lens for
exposure and back in the reverse direction for resetting. The dotted line
represents a connecting cord.
The blind A shown in Fig. 7 is of the most ordinary or commonly used descrip-
tion being attached by the ends to both rollers B and C and wound up upon
the plain roller B to set and drawn from that on to the roller C by the action.
of the spring c for exposure. It is rewound on to the plain roller B to set it for
each exposure,
Whichever of these forms or modifications of blind is adopted the act of setting
the blind for exposure is effected by the operator the blind is held in the set
position against the action of a spring by the releasing mechanism placed at one
side of the shutter (see Figs. 3 and 6) and the duration of exposure is controlled
by the timing mechanism (see Figs. 2 and 5) which can be set or adjusted by
the operator as required.
The releasing mechanism (see Figs. 1 to 6) comprises a disc or wheel D
gearing with a wheel E on the end of the blind roller and provided with a stop d
to engage with a lever F to hold the blind when set and by which it is released
when desired. The lever is raised to release the blind for exposure out of
contact with the stop d on the disc D. The releasing mechanism may be actuated
as in Figs. 1 to 3 by means of a connecting rod F extending from the timing
device placed at the other side of the shutter case or it may be actuated direct
by a pneumatic bulb G placed beneath the lever F or by a pivoted lever G²
with a finger y extending beneath it..
The pneumatic timing device comprises a closed bellows K charged with air
or other fluid with a small port through which the air passes in or out. The
pneumatic timing device is moved in one direction to expel the air from the
interior by a spiral or other spring L enclosed in the casing 1.
This movement is utilized to control the period during which the moving blind
shall be detained at a position of rest during the exposure. The pneumatic
timing device K is attached to one side of the shutter and is provided with
projections one of which serves to hold the device in its expanded position
against the action of the spring L and the other serves to release the blind
after the desired length of exposure.
In the arrangement shown in Figs. 1 to 3 the projection when in its expanded
position engages the catch lever N by which it is held until released by the lifting
of the catch lever N out of its path. This is done by the pneumatic bulb G
placed beneath it. Above the catch lever N is a second pivoted lever F the
end f of which is in the path of the projection & and as it travels down it engages
the end moving it about its centre. This movement is communicated by the
connecting rod F1 to the blind releasing lever F which is thereby raised out of
contact with the stop d on the disc 1) to release the blind.
On the side of the shutter above the pneumatic timing device K is pivoted a
disc provided with a stop pin the disc being rotated with the blind roller by
a pinion o on the end of the blind roller. The stop pin n when it has com-
pleted part of its travel comes into contact with the stop P and is arrested
thereby
In the arrangement shown in Figs. 4, 5 and 6 the catch lever N¹ is elongated

page_text: to reach to the disc and to engage with the stop pin n thereon. As the disc O
is rotated after the release of the blind by the lifting of the lever F by the
pneumatic bulb G₁ the stop pin engages the lever N¹ and moves it out of contact
with the projection thereby releasing the pneumatic timing device K. The
stop pin comes into contact with the stop P and the travel of the blind A is
arrested thereby. The stop P is also pivoted to the shutter and to it is, con
nected a rod carrying at its lower end a ring or the like with which the
projections on the pneumatic timing device K as it travels slowly downward
come in contact and draws down the stop P out of the path of the stop pin n
thereby releasing the blind a second time and permitting it to continue its travel
and complete the exposure.
The time with which the stop pin n remains in contact with the stop P and
thereby determines the duration of exposure is consequent upon the length of
time the projection ¹ takes to travel to engage the end piece pl of the stop P.
This may be controlled by altering the speed of the pneumatic timing device K
or by bringing the end piece p² nearer to the projection and thereby reducing
the time of travel as shown in Fig. 11.
The pneumatic timing device is raised or set by a knob or other suitable
device. A timing device with two bellows shaped chambers K² and K³ may be
employed in which fluid or liquid is forced backwards and forwards from one
chamber to the other and operated by a spring L¹.
The parts of the shutter are so arranged that as soon as the releasing lever F
is raised and the blind released the timing lever N is disengaged from aul
releases the pneumatic timing device K thus commencing the exposure. The
travel of the blind is arrested by the stop pin n against the stop P as soon as
the opening therein is coincident with the opening in the shutter frame or case R.
When the predetermined time of exposure has elapsed the stop P is withdrawn
by the pneumatic timing device K, and the blind allowed to proceed and determine
its exposure.
In this way the shutter may be constructed to give a wide range of exposure
with accuracy say for instance To of a second to 20 or 30 seconds. An indi-
cating device such as a dial S and pointers for instance serves to show the time
of exposure for which the shutter has been set. The timing device on the
shutter is set in motion by any suitable means such as are well known for
instance a pneumatic ball G and tube or by a cord or a trigger.
Referring to Sheet 3 of the drawings Figs. 12 to 26 the blind A is arranged
to move across the lens in one direction for one exposure being wound up on
to one roller and back across the lens in the opposite direction being wound up
on another roller.
Such a blind may be of either of the following constructions.
(a) An endless blind having two apertures passing around two or more rollers
as in Figs. 17 & 18.
:
(b) A single blind having one aperture and attached to two rollers at opposite
ends of the enclosing case as in Fig. 19.
(c) A long single blind with two apertures attached to two rollers placed at
the same end of the case and passing in its travel over one or more additional
rollers placed at the opposite end of the case as in Figs. 20, 21 & 22.
In all cases where a single blind is used as distinct from an endless blind
the two rollers B and C to which the ends of the single blind are secured are
so connected that the blind A and the rollers B and C always move together in
unison.
The rollers may be connected or geared together in a variety of ways such as: -
(a) By connecting cords or bands as shown in Figs. 17 and 18 giving the
practical equivalent of an endless blind.
(b) By a rack gearing with pinions on the blind rollers as in Fig. 23.
(c) By an endless chain passing over sprocket wheels as in Fig. 24.
(d) By tooth quadrants gearing with pinions on the blind rollers as in Fig. 25.

page_text: (e) Or by gear wheels or pinions gearing together as in Figs. 21, 22 and 26.
Whatever arrangement is adopted the point to be observed is that a movement
of one of the rollers in either direction shall cause a similar movement of the
blind and the action is such that the blind is given a reciprocating motion.
The single flexible blind A is mounted upon the two rollers B and C (Figs. 17
and 18) which are also connected together by ends or bands a so that the rotation
of either of the rollers in one direction unwinds the blind from one and winds it
upon the other and vice versa. One roller therefore only require to be operated
to move the blind backwards and forwards or cause it to reciprocate. For this
purpose a spring or springs D are connected to the blind roller B in such a way
that in which ever direction the roller be moved from a stationary position the
springs D will move it in the reverse direction.
At the end of the driving roller is fixed a small pinion b with which a quadrant
disc E gears the relative sizes being such that approximately one half revolution
of the quadrant disc E will give the desired number of revolutions to the pinion b
and blind roller B. Upon the quadrant disc E are fitted two projecting pins e e
with which a pair of pivoted fingers or levers F are caused to engage. The
levers are pivoted on a stud f carried by a sliding plate or bracket f to which
the end of the springs D are also attached. The springs 1 pass round the loose
pulley as there is not sufficient room to allow for its lying altogether in the
direct line of action. The levers Fare made with a notch or shoulder and their
free ends to embrace the pins e and e¹ and as they are moved upwards and come
in contact with the pins the inclined shape of the end causes them to be forced
apart and open with a scissor like action and they then close upon one of the
pins by the action of the springs f². The force of the springs 1) is thus alter-
nately applied first to one pin and then to the other to rotate the dise quadrant E
first in one direction and then in the other as at each movement of the disc the
uppermost pin stops short of the dead centre.
The operating spring may be made to work a direct pull if arranged as shown
in Fig. 16. The spring D is attached to a crank or eccentric D which can be
rotated from the position shown until it rests upon the uppermost side of the
pin e which on the disc being released rotates it the required distance the
pin being raised. The pin e³ can then be acted upon in the reverse direction.
The disc E at the back is provided with a stop or projection y with which
a pivoted detent or finger G engages to hold it against the force or action of the
spring until released. The finger or detent G is drawn back to effect the
release of the blind by the pivoted trigger II operated by the hand or finger of
the operator or in any other convenient way. For time exposure a second
detent G is thrown into engagement with a second projection or stop on
the reverse side of the disc by the second trigger H' which arrests the travel of
the blind and holds it until the detent G is withdrawn. The backward movement
of the trigger lever H' withdraws the detent and permits the travel of the blind
to be resumed.
:
A third detent G2 is placed behind the disc E to engage the stop or projection g¹
for the purpose of time exposure when it is desired to automatically release the
blind after being arrested in its travel by a pneumatic timing device K placed
at the other side of the shutter. The speed of travel of the timing device is
regulated by the escape of the fluid (air or water glycerine or the like) which
it contains.
:
The detent G2 is connected by the connecting rod and bell crank lever
with the sliding finger which is operated or drawn down by the projection
on the timing device K thereby drawing back the detent G2 and releasing the
blind.
The timing device K when set is held in position by the projection
the tumbler which is connected by the connecting rod
When the detent G is drawn back by the trigger lever H to
engaging
with the detent G.
release the blind the

page_text: tumbler is also drawn back and releases the projection of the timing device
the blind and the timing device being released simultaneously.
The blind is stopped and held open by the detent G engaging with the stop g
the rod gremoving the stop g¹ to terminate the exposure. The shutter is re-set
for exposure by the lever F by which the sliding bracket f is raised to connect
the actuating mechanism by means of the levers F with the uppermost pin e on
the disc quadrant E.
The time of exposure is varied by varying the rate of travel of the pneumatic
timing device. An indicating device such as a dial M and pointer m for instance
serves to show the time of exposure for which the shutter has been set.
In Figs. 17 and 18 the two rollers B & C upon which the blind A is wound
alternately are connected by the cords or bands to cause them to work in unison.
In Fig. 19 the blind A is attached to the two rollers B & C and the rollers
are connected together to work in unison by a rack 62 working into pinions 63 3
as in Fig. 23 or by an endless chain or sprocket wheels as in Fig. 24
or by a double quadrant 66 gearing with two single quadrants 7 c which in turn
gear with the pinions 688 on the roller ends. Fig: 25.
In Fig. 20 the single blind A¹ is mounted upon two rollers B₁ C¹ placed side
by side and passed over a third roller C. The two rollers B and C¹ are geared
together by a pinion C placed between the pinions 69c on the roller ends as in
Fig. 26.
In Fig. 21 the blind A2 is similar to that in Fig. 20 the roller C¹ being placed
below the roller B¹ and in Fig. 22 the two rollers B and C are geared together
to rotate in the opposite direction.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is-
1. In a pneumatic shutter with a single spring blind the combination of a
regulatable automatic timing device for intercepting the exposure movement of
the blind and detaining it at any desired period of time forming part of the
shutter and comprising one or more reservoirs such as a bellows or cylinder con-
taining air or other convenient fluid substantially as described and shown.
2. A pneumatic shutter with a single spring blind constructed with a releas-
ing device by which the blind is held when set and subsequently released and an
adjustable pneumatic timing device by which the travel of the blind is arrested
and re-started when the exposure is complete substantially as described and
shown.
3. A photographic shutter having a single flexible blind which moves to and
fro for each exposure constructed with mechanism connecting the rollers to
cause them to work in either direction in unison, a driving spring connected to
one roller, to actuate it in either direction, mechanism for connecting the spring to
the roller and setting it to operate first in one direction and then in the reverse
direction mechanism for releasing and setting the blind in motion and an auto-
matic pneumatic timing device for stopping and re-starting the blind substantially
as described and shown.
4. A photographic shutter constructed with mechanism for connecting the rollers
to work in unison in either direction, a disc gearing with a pinion on the end of
the blind roller provided with two projecting pins and mechanism for connecting
a spiral spring acting in the direction of its length alternately with the pins to
rotate the disc and the blind roller first in one direction and then in the reverse
direction substantially as described.
5. A photographic shutter with a single blind constructed with a pinion E on
the end of the blind roller B gearing with a second pinion or wheel I provided
with a stop to engage the releasing lever F, a pinion o on the other end of the
blind roller gearing with a toothed wheel or disc O provided with a stop pin n
a catch lever N or N¹ which engages with the pneumatic device K, stop P which

page_text: engages the stop pin n on the disc O and the automatic pneumatic timing device K
which is held and released by the catch lever N and which releases the stop P
at the termination of a pre-determined period substantially as described with
reference to Figs. 1 to 11.
6. In a photographic shutter the combination with a disc gearing with a
pinion on the end of the blind roller of a pair of pivoted levers attached to an
actuating spring, or a single lever pivoted on the disc axis, which engage with
pins on the rotating disc to rotate the blind first in one direction and then in the
reverse direction substantially as described with reference to Figs. 12, 14 and 16.
7. A photographic shutter comprising in its construction a flexible blind
mounted upon rollers, two rollers to which the blind is attached mechanism con-
necting the rollers to work in unison in either direction, a driving pinion on the
roller end, a toothed disc E provided with projecting pins gearing therewith, a
long spiral driving spring D acting in the direction of its length mechanism for
connecting the driving spring alternately with one and then the other of the
pins on the toothed disc E a detent G to hold the roller when set, two detents G¹ G²
to arrest the travel of the roller for time exposures, a pneumatic timing device K
connected with the detents G & G tumbler k¹ to hold up the timing device when
set the connecting rod connecting it with the detent G the sliding finger g* upon
which the timing device acts to withdraw the detent G2 the bell crank lever g³
and rod connecting it with the detent G2, the trigger lever H to release the
detent G and the trigger lever H₁ to release the detent G₁ substantially as
described, with reference to Figs. 12 to 25.
8. A photographic shutter with single flexible blind constructed and arranged
substantially as described and shown with reference to either of the Figs. of the
drawings.
.
Dated this 29th day of January 1900
WM. P. THOMPSON & Co.,
6. Bank Street, Manchester, Patent Agents.