Large preparation (dissecting) microscope with erecting prism
Model W, c. 1925
The first application of this erecting system to a
Leitz dissecting microscope was reported in the
Journal of the Royal Microscopical Society,
1900. It was incorporated into the microscope designed
by Richard Friedrich Johannes Pfeiffer
(1858-1945). An extract from the Journal is reproduced below:
Pfeiffer's New Preparation
Microscope.This has been designed by Prof.
Pfeiffer to meet a want felt by him in his work on
malarial parasites. He considered that an instrument of
this kind should give an erect image, a maximum
object-distance, large field, and sufficient
magnification. Fig. 123 shows the Microscope, which is
built on the ordinary principle, but the inverted image
produced by the objective is by a suitable prism
arrangement presented to the eye as erect. These prisms
are contained in a somewhat wide brass tube, which on
its under side carries the objective eccentrically, and
on its upper the ocular. The bending of the light-path
shortens the tube length, so that the eye is only 13-l5
cm. above the stage on which the hands work. Three
objectives are supplied ; No. 1 gives 32-fold
magnification at 45 mm. object distance; No. 2, 44-fold
at 25 mm.; and No. 3, 65-fold at 15 mm. In spite of the
passage of the light through the prisms, the image is
full of light, sharp, and free from chromatic defects.
The optical part is mounted on a firm stand with rack
and pinion; the stage is spacious, and has supports for
the hands. The stage-opening is provided with iris
diaphragm, and the whole instrument can be very
conveniently packed into a light box. The maker is Herr
Leitz. Erection of the microscopic image by means of
prisms was first effected by Ahrens. The same idea was
carried out by Zeiss in 1895.
The erecting tube utilizes a Porro prism. The light
path through the optics is illustrated on the left.
Subsequently, this erecting apparatus was supplied with
other Leitz dissection stands such as the model shown
on this page. It is described in the 1929 catalog as
the "Dissecting Microscope Model W".
From the 1929 Leitz catalog:
Focusing Adjustment — By rack and pinion with milled head on either side, giving a range of 80mm.
Stage Glass — 80 x 95mm, removable; second set of grooves beneath stage accommodate a metal plate , with circular disc to provide white or black background; spring clips attached to stage support.
Hand Rests — Of metal, 90mm in length and detachable, leather covered.
Base and Pillar — Base of metal, modified horseshoe form; round pillar, of metal, attached to base.
Mirror — Plano 50mm diameter, one side of opal glass; mounted on swinging arm.
Lens — “Doublet” or triple “Aplanat” are regularly supplied; lens arm will hold any of our regular magnifiers for dissecting microscopes
Finish — Base in black alcohol proof lacquer, pillar in blond lacquer.
Case — Of wood, highly polished and fitted with lock and key.