Improvements in the Condensers of Optical Lanterns.
Year: 1893

page_text: Date of Application, 27th Feb., 1893
Complete Specification Lelt, 27th Nov., 1893-Accepted, 30th Dec., 1893
PROVISIONAL SPECIFICATION.
Improvements in the Condensers of Optical Lanterns.
I WILLIAM ISAAC CHADWICK of 2 St. Mary's Street Manchester in the
County of Lancaster Scientific Instrument Maker do hereby declare the nature of
this invention to be as follows:-
My said invention relates to condensers for optical or projection lanterns.
Such condensers are in modern lanterns constructed with two or more lenses forming
a compound system and it is desirable to have means for readily varying the focal
length of the system.
This variation of the focal length is most conveniently effected by substituting
for one of the lenses of the compound system another lens of different focal length.
The object of my said invention is to enable such substitution of the lenses to be
readily effected.
For this purpose I mount the lenses to be exchanged in cells having tubes or
adapters sliding into a corresponding tube carrying the remaining lenses.
In the latter tube form two or more diametrically opposite hollows or inlets
opening outwards in the direction in which the lens is to be withdrawn and through
which the aforesaid inner adapter or tube can be grasped. On the latter tube is a
rim or projection and in some cases holes for greater convenience in extracting
the lens.
Dated this 25th day of February 1893.
EDWARD TURNER WHITELOW,
70, Deansgate, Manchester, Agent for Applicant.
P
COMPLETE SPECIFICATION.
Improvements in the Condensers of Optical Lanterns.
I WILLIAM ISAAC CHADWICK of 2 St. Mary's Street, Manchester, in the
County of Lancaster, Scientific Instrument Maker, 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:-
My said invention relates to condensers for optical or projection lanterns. Such
condensers are in modern lanterns constructed with two or more lenses forming a
compound system and it is desirable to have means for readily varying the equivalent
focal length of the system.
This variation of the focal length is most conveniently effected by substituting
for one of the lenses of the compound system another lens of different focal length.
The object of my said invention is to enable such substitution to be readily
effected.
For this purpose I mount the removable lens or lenses in a cell having a tube
adapter sliding into a corresponding tube or mounting carrying the remaining
lenses.
Referring to the accompanying drawing
Figure 1 is a section and Figure 2 an outside view showing the application of my
said invention to a triple condenser.
a is the external mounting or jacket shaped to suit the lantern in which it is to be
used and carrying two lenses bc and a plane plate d to protect the lens 6 from the
heat of the illuminating agent. e is one of a set of sliding adapters each carrying
lenses of different degrees of curvature so that by withdrawing one adapter with.
[Price 8d.1

page_text: its contained lens and substituting another one of the set the equivalent focal length
of the triple condenser may be varied.
Two or more diametrically opposite hollows or inlets g opening outwards are
formed in the mounting a through which the adapter e may be easily grasped
and a rim his formed on the adapter for greater security and convenience in
withdrawing.
The lengths of the adapters or the position of the lenses mounted therein are
varied to suit the curvature of the lens so as to bring it into the proper position
with regard to the remaining elements of the combination.
In lieu of hollows such as g part of the length of the mounting a may be cut
clear away to the dotted line to enable the adapter to be grasped at any point.
In this case a stop or projecting rim k is formed in the interior of the mounting a
against which the end of the adapter e may abut when the adapter is pushed
home.
The lenses are secured in the mounting a and in the adapter e by means of
screwed cells or by a burnished rim in the usual way.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is―
1. A compound condenser for optical lanterns whose equivalent focal length may
be varied by substituting for one of the lenses another of different curvature
mounted in an adapter sliding longitudinally in a mounting provided with hollows
such as g or an annular clearance in lieu thereof to enable the adapter to be grasped
as set forth.
2. In a compound condenser for optical lanterns the combination of the
mounting a having clearance to enable the contained adapter to be grasped and
provided with internal stops k and the internal adapter e carrying the removable
Tens of the system substantially as set forth.
Dated this 25th day of November 1893.
EDWARD TURNER WHITELOW,
70, Deansgate, Manchester, Agent for the Applicant.