AN IMPROVED FORM OF CONDENSER FOR THE MICROSCOPE
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
I GEORGE CHARLES WALLICH, M.D., Surgeon-Major Retired List, Her Majesty's
Indian Army, residing at 26 Addison Road North, Notting Hill, London, do
hereby declare the nature of the said Invention for AN IMPROVED FORM OF
CONDENSER FOR THE MICROSCOPE to be as follows:-
An optical combination consisting of a cone of glass or other suitable optical
material, with one or more lenses, all so arranged in a metallic or other setting as
to admit, if necessary, of the distances between them being modified in a manner
which shall produce the best results in this mode of illumination. I also claim
that this Invention, besides providing a superior illumination, materially increases
the "penetration" of the objectives employed along with it; & that, when used
with the binocular microscope, it also materially increases the stereoscopic effects.
Dated this Thirteenth day of May 1884.

page_text: I GEORGE CHARLES WALLICH, M.D., Surgeon Major on the Retired List of
H.M. Indian Army, residing at 26 Addison Road North, Notting Hill, in the
Parish of Kensington, in the County of Middlesex, do hereby declare the nature
of my Invention for AN IMPROVED CONDENSER FOR THE MICROSCOPE and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement:—
My Invention relates to improvements in condensers for the purpose of
illuminating objects under the microscope in order to obviate the difficulty which
has hitherto been experienced in adequately illuminating objects having considerable
depth, and more especially when such objects are being examined in the binocular
microscope & with objectives of high magnifying power. My Invention likewise
extends the range in depth through which more or less transparent objects may
be distinctly seen in the microscope; &, when used with the binocular instrument,
facilitates the production and increase of true stereoscopic effect.
These improvements consist in the employment of one or more truncated cones
or pyramids of glass, rock-crystal, or other suitable transparent material in
combination with one or more lenses capable of being so adjusted with respect to
one another as to produce the most satisfactory results. The surfaces of the before
mentioned cones or pyramids are highly polished so as to constitute an internally
reflecting surface by making the cone or pyramid of such an angle as to produce
the optical phenomenon known as "total reflection;" or a like result may be
obtained by the employment of a hollow cone or pyramid made of metal or glass
or other suitable material polished on its internal surface and used in conjunction
with a lens or lenses as aforesaid.
Although I employ, by preference, solid cones, pyramids, and lenses, constructed
of glass or other transparent material, I would point out that these may one or all
be made hollow & afterwards filled with a fluid transparent and refracting
medium; but be it understood that I make no claim to the Invention of
condensers, whether conical or otherwise, in which the phenomenon of reflection
takes no part, the essence of my Invention being the cata-dioptric combination of
a lens or lenses with a conical or pyramidal reflecting surface as aforesaid.
In order to make the description of my Invention more clear, I have illustrated
it by means of a Drawing attached to this Specification. In this Drawing, A is a
cone of glass or other suitable material mounted in a cell D and having a lens B
attached to its larger end either by means of a transparent cement or by any
equivalent mechanical device; or the cone A may be made with a convex or
concave base so as to bring about the same result when in combination with
another or other lenses; and the combination may, if required, be made achromatic
by constructing it of materials possessing different indices of refraction in
accordance with optical principles well known to makers of optical apparatus.
C is a second lens of larger light-collecting capacity than that already described,
& mounted in suitable fittings E and F by which its distance from B can be
adjusted so as to produce various desired effects.
As improved effects may, in many instances, be produced by curtailing or
preventing the admission of light into the condenser from one or other side of the
lens C, I have for this purpose added a shutter G pivotted at or near the
circumference of the cylindrical fitting F1 by a screw or pivot S, which shutter
can be set in any required position by moving the knob T, or by rotating the entire
condenser in or by its fittings to the requisite extent.
For the purpose of producing various effects of illumination I make use also of
diaphragms furnished with openings of various shapes and sizes, placed either

page_text: between the lenses B and C, or in front of the smaller polished transmitting end
of the catadioptric cone A.
In describing the foregoing method of mounting and fitting, I wish it to be
understood that I do so to illustrate one out of many devices which may be
advantageously employed for mounting the optical portions of the condenser
herein before referred to, & for attaching it to the microscope, & that I make no
claim to this or any particular method of effecting this result.
Having now particularly described and ascertained the nature of my said
Invention, & in what manner the same is to be performed, I declare that what I
claim is,
(1.) The combination with a lens or lenses of a truncated cone or pyramid
constructed of glass or other transparent & refracting material so designed as to
concentrate rays of light transmitted through it, partly by internal reflection from
its conical or inclined surface, & partly by refraction through the transparent
material of which it is composed and of the form and construction and for the
purposes hereinbefore set forth.