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Transactions of the Society. 
same way for numerous stage forceps ; but, inasmuch as its rotation 
with these in place would bring their projecting ends against the pillar 
of the Microscope, the direct connection of the latter with the foot 
is severed, and it is inserted instead on a projecting lip of the stage 
upon which it is centered by being fitted loosely in a hole, where 
it is clamped in concentricity with the diaphragm by the clamping 
screw seen underneath. It is expressly admitted by Strauss-Durck- 
heim that the working out of this feature was effected by M. Trecourt, 
Oberhaeuser’s senior partner ; and here we may ask for the original 
source of such a model. The inventor having stated that he originally 
worked “ with a Microscope which, by a kind of chance, was of small 
dimensions,” there was only one pattern extant at the time, which 
corresponds to this description and could have served as a basis for 
the design. This is the so-called drum Microscope, shown in fig. 91, 
which is now only used for toys, but was 
Fig. 90. Fig. 91. a( j 0 pt e d by the optician Fraunhofer, of 
Munich, as a regular pattern about 1815, 
and was certainly manufactured in Paris 
by Chevalier, Lerehours, Trecourt, and per- 
haps others from 1830 onwards; and it is 
not difficult to see how the combination of 
this stand with a rotating stage would result 
in the design of fig. 90.* Returning to this 
instrument it will be noticed that the pillar 
which carries the body is enveloped in two 
outer tubes or sleeves, the inner of which, 
by means of a micrometer screw and spring, 
slides up and down to afford the now familiar 
form of fine-adjustment, whose milled head is seen below the clamping 
screw which its stem perforates ; while the outer is intended to allow 
the body to be swung to one side through an angle of 90°, when a 
simple lens mounted on another stand is to be brought over the 
dissection — a necessity only likely to be foreseen by an anatomist. 
The tube of the Microscope itself is so evidently adapted from fig. 91 
as to need no observation, and the only novelty is that it is double 
within, so as to permit of the use of a second objective above the first, 
as an erector, an original feature for which Strauss-Durckheim can 
also claim priority.! 
* An exact apportionment of the credit between the joint inventors is difficult to 
make after this lapse of time, and beyond the main purpose of this paper. Chevalier 
in the pamphlet quoted (‘ Notes Eectificatives, &c.’), tells us that Trecourt and 
Oberhaeuser on beginning the manufacture of Microscopes about 1830, employed this 
stand of Fraunhofer's exclusively, which had the advantage over all others in 
cheapness. The remainder of this pamphlet is occupied with a controversy about 
priority in the matter of achromatizing objectives, with which we have nothing to do, 
on the present occasion. 
t On this point, and Trecourt and Oberhaeuser’s subsequent introduction of such 
a feature in a Microscope of their own, see Strauss-Durckheim’s ‘TraiteV fpagg. cit. 
also Comptes Rendus, ix. p. 322, sitting of the Academie des Sciences, Sept. 2, 1839. 
