368 
Transactions of the Society. 
adjustment, and screw stage fine adjustment, which was almost 
identically the same as that of Chevalier’s. We now come to the 
Oberhauser Microscope, about which there has been some controversy. 
Oberhauser ( 36 ) designed a Microscope with rackwork coarse adjust- 
ment fitted to the body- tube, and rackwork to the draw- tube, but 
with no fine adjustment; this instrument was called a dissecting 
Microscope, its date is probably as early as 1835. Oberhauser made 
two other models ; one ( 37 ) had the rackwork transferred from the 
body to the pillar, the body being fitted with a push-tube, and a fine 
adjustment added by means of a screw on the top of the pillar acting 
against a spring ; this Microscope was patented in 1837. In another 
( 38 ) Microscope, the rackwork coarse adjustment was entirely re- 
moved, the push- tube coarse adjustment being retained, and the 
screw-nut of the fine adjustment placed at the bottom of the pillar. 
In all these models the limb which held the body was attached to the 
rotary stage, so that when the stage was rotated the body was rotated 
with it. This plan was for some years adopted by Messrs. Zeiss; but 
it is now entirely given up in favour of the English form of concentric 
rotary stage designed by M. S. Legg in January 1848. It is not 
quite clear which of these three forms of the Oberhauser was the 
earliest ; the order given in the text is probably that most generally 
accepted. Two points of originality in design can be credited to 
Oberhauser : 1st, the fixing of the limb to the rotary stage ; 2nd, the 
fitting of rackwork to the draw-tube. (This was employed solely 
for the regulation of the magnifying power ; it was, however, re-intro- 
duced by me some years ago for the purpose of lens correction, and 
it has now, in this country at least, become very general.) 
To sum up, therefore : — From the year 1771 to the point we have 
now reached, we find nine types of Microscopes without any fine 
adjustment, and six with ; and of the six which had fine adjustments, 
five of them had nothing better than that designed by Cuff in 1744. 
The best fine adjustment we have met with as yet is that of Ober- 
hauser’s screw-nut acting against a spring (patented 1837). We 
shall, however, be able to predate this by better forms invented in 
this country. 
One of the workers to whom we are to-day indebted for many 
improvements in the mechanical portion of the Microscope is Cornelius 
Yarley ; but so far as I am aware, his work has never been recognised 
by any writer. Mr. Mayall, for instance, in his Cantor lectures, says, 
“ I purposely exclude Cornelius Yarley, for, in my opinion, most of 
his contributions to the mechanism of the Microscope bordered so 
much on the bizarre, that their influence has retarded rather than 
advanced the best points of construction.” I think, however, that 
when you have heard the evidence I have to bring before you, you 
will reverse this view of the case. It is not sufficient merely to look 
at the outside form or shape of any particular instrument, and if such 
prove to be of a bizarre nature, to discard all further notice of it, but 
