Improvements in Magic Lanterns.
Year: 1892

page_text: Date of Application, 1st July, 1892-Accepted, 6th Aug., 1892
Improvements in Magic Lanterns.
I HERBERT CHARLES NEWTON, Scientific Instrument Maker, 3 Fleet Street,
London, E.C., 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 biunial and triple lanterns, the discs of which are made
to coincide on the screen.
In such lanterns, the front plates carrying the lenses are hinged so as to be
capable of tilting to converge the rays upon the same spot of the screen, from
whichever division of the biunial or triple lantern they are projected.
This tilting of the lenses has the effect of diverting the optical axis from the
horizontal to an inclined plane, and a difficulty is thus introduced in connection
with the luminant, which it is the object of my invention to obviate.
The tray carrying the luminant usually slides in grooves on the base of the
lantern, so that the luminant can be moved backwards and forwards towards and
away from the condenser along the line of the optical axis. But when the front
carrying the lenses is tilted, as above described, the motion is no longer in the line
of the optical axis, and the value of the adjustment is thereby considerably
diminished.
It is desirable, to obtain the best results, that the luminant should be maintained
on the line of the optical axis, and be capable of travelling to and from the
condenser, without moving out of the optical axis, and to this end I carry the lamp
on supports rigidly secured to the lantern front, which also carries the lenses, so
that the lamp follows the tilting movement of the front plate, to maintain the
luminant in the optical axis of the lenses.
In the accompanying drawing, I shew a biunial lantern, of which the portion A
is situated over the portion B. To make the discs from these two portions coincide
on the screen, the front plate carrying the lenses of the lantern A is hinged at a,
and the front plate of B is hinged at b, in the usual way.
Hitherto, in lanterns of this class, the tilting of the front plate, as, for instance,
the front plate of the lantern A, to the position indicated by dotted lines, renders
special adjustment necessary to put the jet in the optical axis, and even with such
special adjustment, it will not remain in it, if the jet be moved towards or away
from the condenser.
According to my invention, the jet C, or the tray carrying it, is mounted on a
base rigidly connected to the front plate, preferably by means of a pair of tubes D,
firmly socketted to the metal front.
The drawn and the dotted positions of the jet C, tube D, and the front plate of
the lantern A, shew clearly how these parts retain their relative positions with
regard to the optical axis, also indicated by dotted line. The adjustment of the jet
or other source of illumination is thus unaffected by the changed position of the
optical axis, and is therefore much simplified.
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 :-
In biunial and triple lanterns, the employment of supports for the luminant,

page_text: rigidly connected with the hinged or moveable front plates which carry the lenses,
substantially as described, and for the purpose set forth.
Dated this 1st day of July 1892.
NEWTON & SON,
Agents for the Applicant.