IMPROVEMENTS IN THE CONSTRUCTION OF STEREOPTICONS
Year: 1872

page_text: PROVISIONAL SPECIFICATION left by George Davies at the Office of
the Commissioners of Patents, with his Petition, on the 20th April
1872. A communication from abroad by Albert Gibbons Busby
and Walter Bentley Woodbury, both of Philadelphia, Pennsylvania,
United States of America.
I, GEORGE DAVIES, of 4, St. Ann's Square, Manchester, in the County
of Lancaster, Consulting Engineer and Patent Agent, do hereby declare
the nature of the said. Invention for "IMPROVEMENTS IN THE CONSTRUCTION
OF STEREOPTICONS," (a communication to me from abroad by Albert
Gibbons Busby and Walter Bentley Woodbury, both of Philadelphia,
Pennsylvania, United States of America,) to be as follows:→
This Invention consists of certain improvements in stereopticon-
apparatus, the said improvements having been designed mainly with
the view of rendering the apparatus compact and economical and of
enabling it to be readily operated.
It is desirable that a stereopticon apparatus should be duplex, that is,
that it should have two lanterns or burners and two separate sets of

page_text: lenses, which can be directed to the same portion of the canvas, in order
that the pictures may be produced upon the latter in quick succession
by what is known as the dissolving process, which consists merely in
gradually turning off the light of one burner simultaneously with the
turning on of the other, thus causing one picture to gradually fade out
from the canvas while another takes its place. It is also desirable for
convenience in managing the two sets of picture slides that the parts of
such duplex apparatus should be arranged one directly above the other,
but this has heretofore been considered impracticable, owing to the fact
that the heat of the lower burner, especially when lime lights are used,
is so great as to deteriorate and in time destroy the fixtures of the
upper burner. The parts of duplex apparatus are therefore commonly
arranged side by side, which involves the necessity of introducing the
picture slides from opposite sides and therefore compels the operator
either to lean over the top of or walk around the apparatus every time
the slides have to be changed. This Invention overcomes the difficulty
so as to enable one set of burners and lenses to be arranged directly
above the other by extending a partition or deflector across the casing
of the instrument between the two burners, and by providing a side
chimney for carrying off the heat from the lower burner as I will now
proceed to describe. A rectangular box forms the casing of the
apparatus, and to the front of the case are hinged two blocks which
carry the upper and lower condensing lenses and the front lenses, the
latter being adjustable towards and from the condensing lenses upon
arms which project outwards from the hinged blocks. The latter are
held in position and are arranged to be adjusted to such angles that
the two sets of lenses shall both be directed towards the same point upon
the canvas by set screws adapted to nuts in the case. Two lime lights.
or burners are used one of which is contained in the lower compartment
and the other in the upper compartment of the case, these two com-
partments being formed by a horizontal or slightly inclined partition
which extends entirely across the case and serves as a deflector to
protect the upper burner fixtures from the deteriorating effect of the
heat of the lower burner. This heat is conducted off through a side
chimney communicating at its lower end with the lower compartment
and extending upwards through the upper compartment at one side of
the same to the chimney proper at the top of the apparatus. The side
chimney may, however, if desired, be arranged outside of instead of
within the case.

page_text: •
· It is preferable that the defector or partition should consist of a douDIB
casing of metal as in this form it is a better. non-conductor of heat than
if made solid.
66
It is desirable in some cases that three or even four instead of two
burners should be arranged one above the other, and this it 'will be
evident can be accomplished by the use of the side chimney and parti-
tion without risk of heating the upper burner. The lime lights used
are of ordinary construction, the pencil of lime being held in a cup at
the 'upper end of a rod, and being played upon and heated to a white
heat by an oxyhydrogen jet from a nozzle, the gases being supplied to
each burner. through two pipes furnished with cocks, and a two-way
dissolving" cock being secured to the back of the apparatus and
communicating with both sides of the pipes through short lengths of
hose, by means of which cock the gases may be simultaneously cut off
from one burner and turned on to the other. As the pencils of lime
are being constantly consumed it is necessary that they should be fed up
to the nozzles and also be constantly turned in order that the greatest
brilliancy may be obtained. This is sometimes accomplished by expen-
sive clockwork, but the limes are more generally turned and fed up
by hand, and therefore require the constant attention of the operator.
In this apparatus the limes are adjusted in the act of putting in or
taking out the picture slides, or of turning the dissolving cock, and do
not therefore require any special attention from the operator. Where
the limes are to be operated by the picture slides a rod or wire extends
through a slit in the front of the case and across the space into which
the picture slide is inserted, so that in forcing down the said' slide into
its space the rod shall also be depressed and rise again by the action of
a spring when the said slide is' raised. This rod is connected to a plate
secured to a spindle, a cog wheel on which gears into a wheel on the
screw rod carrying the lime. The rod is slotted for the reception of a
feather on the wheel which permits it to slide through but not to turn
independently of the latter. By means of these devices and a ratchet
connection the intermittent rotary movement imparted to the spindle
by the rod acted on by the picture slides is transmitted to the screw
rod carrying the limo which is thus gradually raised until the lime is
consumed.

page_text: The mechanism can be turned at any time by hand by means of a
button at the front end of the spindle, in such a direction as to either
raise or lower the lime.
A somewhat simpler arrangement of transmitting mechanism consists
of an arm upon the spindle, the hinged end of which strikes and turns &
a pin wheel on the lime rod. The latter also instead of being threaded
has a pin which traverses a spiral slot cut in a tube within which the
lower end of the lime rod is contained. When the limes are to be
operated from the dissolving cock the operating rods. are passed through
the slotted ends of a vertical bar, a rack on which gears into a toothed 1
wheel at one end of the dissolving cock, so that whenever the latter is
turned tho said bar and rods will also be operated. .
·
As it is often necessary to tilt or incline the whole apparatus in one
direction or the other in order that the lenses may point directly on to
the canvas, there is secured to the front and near edges of the base two 1
hinged strips or pitching boards, by turning either of which downwards
so as to support the apparatus at one end. the latter may be inclined in
one direction or the other as desired.
A block is secured to the rear end of each front lens, and to this block
are hinged two or more arms carrying plates of colored transparent glass 2
which can be turned downwards over the rear end of the lens for the
purpose of tinting the picture, and it is intended also that one of the
said arms shall carry a piece of cloth or other opaque material which
when turned downward against the lens shall entirely darken and
obliterate the picture from the canvas.
.
Another modification of lime movement and burner is still more
simple in its operation than those before described. The whole move-
ment is supported upon a single pedestal or stem and retained thereon
by a set screw enabling it to be readily detached when necessary.
A spring is also fastened to one of the pipes of the burner instead of to 3
the base which avoids the necessity of detaching the spring from the
latter when the burner has to be disconnected from the base.
Another improvement is the employment of a simple pawl and
ratchet movement for raising the lime cup in place of the more com-
plicated devices previously described.
3

page_text: The nozzle or blow pipe has a tapering lower end adapted to a
similarly shaped opening in the body of the burner. This enables the
said nozzle to be readily attached and detached and forms a ground
joint by which leakage is much more effectually prevented than by the
usual screw connection.