IMPROVEMENTS IN OPTICAL LANTERNS
Year: 1886

page_text: HENRY MARTYN WHITEFIELD, 54, Yarburgh Street Manchester Manager SAMUEL
WASHINGTON 19 Radnor Street Manchester, Manufacturing Chemist, do hereby
declare the nature of this invention for IMPROVEMENTS IN OPTICAL LANTERNS
to be as follows:-
This invention relates to Optical Lanterns. The object is to effect a rapid
change of the pictures exhibited on the screen by a single lantern and by means
of a novel arrangement for shutting off the light, to do this without the changing
of the pictures being visible and to prevent any possibility of vibration or move-
ment of carrier during the insertion of a new slide.
The invention consists in fitting in the front part of the lantern between the
condensers and objectives a suitable shutter or shutters worked from behind the
lantern by. means of a shaft running from front to back and having a handle fitted
A cam and crank fixed on the end of the shaft closing the shutters and
opening them again.
to it.
•
Whilst the shutters are closed a lever acted upon by the crank is made to pass
forward a double carrier thus changing the picture. The carrier is now held
firmly in position by a powerful spring and the shutters are opened again when
the new picture appears upon the screen. These combined movements are effected
by one half-turn of the handle, and being almost instantaneous the sheet is.
darkened only for a moment, besides which the ludicrous effect of landscapes &c.
sliding across the sheet produced by changing the pictures in the manner that
has hitherto been customary is entirely avoided.
The action will be more readily understood by reference to the accompanying
drawings in which Figure 1. represents a vertical longitudinal section of the
lantern Figure 2. a vertical transverse section and Figure 3. a plan.
In Figure 1-a. a. are two shutters worked from the shaft b. b. by means of the
crank c. on the arm d. the shutters opening in the direction shown by the dotted
lines and arrows, the shutters are closed by the wire c. in conjunction either with
the spring f. or by a suitable weight.g. is the carrier in front of the condensers
which is held in place on the carrier bar h. by the spring and bar i. at the top, and
at the bottom by the pins k. k, see Figure 2.-The carrier is moved by means of

page_text: the lever from the crank c. The carrier is held firmly in position during the
exhibition of a picture by means of the flat spring m. this spring is fixed to a
small hinged flap n. the flap is depressed and the spring brought to bear upon the
carrier by the action of the cam at the front of the crank c.-See Figure 2. The
spring o. serves to raise the flap and so draw back the spring m. while the carrier
is being moved. The shaft b. b. is made in two parts connected about the middle
by the coupling p. the part attached to the handle being removable, when joined
the coupling is kept closed by the spring r. The objective is focussed from the
back of the lantern by means of a sliding bar and elbow worked by a rack and
pinion 8. or by a screw of coarse pitch on the bar and a suitable nut, the bar being
attached to the objectives by the screw t.

page_text: HENRY MARTYN WHITEFIELD 54 Yarburgh Street Manchester, Manager, SAMUEL
WASHINGTON 19 .Radnor Street Manchester, Manufacturing Chemist do hereby
declare the nature of this invention and in what manner the saine is to be
performed, to be particularly described and ascertained in and by the following
statement:-
This invention relates to Optical Lanterns. The object is to effect a rapid
change of the pictures exhibited on the screen by a single lantern and by means
of a novel arrangement for shutting off the light, to do this without the changing
of the picture being visible and to prevent any possibility of vibration or move-
ment of carrier during the insertion of a new slide.
The invention consists in fitting in the front part of the lantern between the
condensers and objectives à suitable shutter or shutters worked from behind the
lantern by means of a shaft running from front to back and having a handle fitted
to it. A cam and crank fixed on the end of the shaft closing the shutters and
opening them again. Whilst the shutters are closed a lever acted upon by the
crank is made to pass forward a double carrier thus changing the picture, the
carrier is now held firmly in position by a powerful spring and the shutters are
opened again, when the new picture appears upon the screen. These combined
movements are effected by one half turn of the handle and being almost instan-
taneous the sheet is darkened only for a moment, besides which, the ludicrous
effect of Landscapes &c sliding across the sheet produced by changing the pictures
in the manner that has hitherto been, customary is entirely avoided.
The action will be more readily understood by reference to the drawings left
with the provisional specification in which Figure 1 represents a vertical longi-
tudinal section of the lantern-Figure 2. a vertical transverse section and Figure 3.
a plan.
In Figure 1-a. a. are two shutters worked from the shaft b. b. by means of the
crank c. on the arm d. the shutters opening in the direction shown by the dotted
lines and arrows, the shutters are closed by the wire, e. in conjunction either with
the spring, f. or by a suitable weight. g. is the carrier in front of the condensers
which is held in place on the carrier bar h. by the spring and bar i. at the top and
at the bottom by the pins k. k. see Figure 2.-The carrier is moved by means of
the lever l. from the crank, c. The carrier is held firmly in position during the
exhibition of a picture by means of the flat spring, m. this spring is fixed to a
small hinged flap, n. the flap is depressed and the spring brought to bear upon the
carrier by the action of the cam at the front of the crank c. see Figure 2.-The
spring o. serves to raise the flap and so draw back the spring m. while the carrier
is being moved. The shaft b. b. is made in two parts connected about the middle
by the coupling p, the part attached to the handle being removable, when joined
the coupling is kept closed by the spring r. The Objective is focussed from the
back of the lantern by means of a sliding bar and elbow worked by a rack and
pinion 8., or by a screw of coarse pitch on the bar and a suitable nut, the bar being.
attached to the objectives by the screw t.

page_text: 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. The combination with the shaft passing from the back of the lantern of the
cam, levers, springs, and shutters or fans substantially as and for the purposes
described.
2. The combination with the shaft passing from the back of the lantern, of the
cam, hinged flap and springs for holding the carrier in position substantially as and
for the purposes described.
3. The combination with the shaft passing from the back of the lantern of the
crank and lever for changing the carrier, substantially, as and for the purposes
described.