PROCEEDINGS OF THE SOCIETY. 
563 
liis to condemn the Zentmayer system of fine-adjustment, and he had not 
condemned it until Messrs. Eoss had gone through a most exhaustive 
series of experiments with the system, resulting in the abandonment of 
their patent rights, and in their adopting other systems for their best 
Microscopes. The fact that Messrs. Eoss allowed the patent to lapse 
was the severest condemnation of Zentmayer’s system of fine-adjustment. 
He might add that Messrs. Eoss had submitted all their experimental 
devices to himself for trial, and that every step that had been taken in 
the matter was thoroughly discussed by Mr. Wenham and others before 
the Zentmayer system was given up. After this experience, he had felt 
justified in condemning the system frankly in his Cantor Lectures at 
the Society of Arts, and his criticism was published five years ago in the 
Journal of that Society. Dr. Van Heurck had received a copy of the 
reprint of those lectures, and might at any time have asked him for 
fuller details if he had thought proper to do so. It was hardly to be 
expected that he should seek information of that kind from Dr. Yan 
Heurck, who had hitherto been totally unknown as taking any special 
interest in the design of Microscopes or microscopical apparatus ; and 
he must confess that the recent discussion on the design of the “ Yan 
Heurck ” Microscope had not impressed him with Dr. Yan Heurck’s 
knowledge of the mechanism of high-class Microscopes. It was, surely, 
a matter of common knowledge that a skilled manipulator could execute 
extremely delicate work with a Microscope of very inferior construction. 
Dr. Van Heurck’s challenge to himself to a competition in manipulation 
would, if accepted, really end in no useful result. Whether one Micro- 
scopist could or could not do with inferior means what another had done 
with the best means available, would not advance the construction of the 
Microscope a jot. Instead of an idle competition of that kind, it would 
be infinitely preferable that experts in microscopical manipulation should 
frankly compare notes of past experience, and join in the promotion of 
the highest excellence attainable in the mechanical and optical construc- 
tion of the Microscope. He thought the question of their right to free- 
dom of discussion of the matters brought before them had been admirably 
laid down by Dr. Dallinger, who, in writing to him on the subject, had 
expressed himself as follows : — 
“ Our criticisms of instruments and apparatus are judicial — absolutely 
unbiased, and wholly on the merits of the subject, or they are of no value 
— nay, they are pernicious. If ours were a debating club there might 
be limits to the ‘right of reply.’ We are a society seeking truth on a 
special subject. If a man happens to be able to add to or elucidate a 
truth by rising four or five times, and before or after any one else, I take 
it that he may and should do so. But as a matter of fact, I rose to 
criticize a principle, not a thing. My remarks on the thing were inci- 
dental. I merely demanded our right to criticize favourably or adversely, 
as our judgment dictated ; and that carried with it the consequent 
impropriety of any attempt to retort. A modest reply would be different.” 
He thought he need not read the remainder of the letter, though it 
emphasized Dr. Dallinger’s agreement with the adverse criticism of the 
Yan Heurck Microscope. He desired it to be clearly understood that 
when he criticized a Microscope, he did so in his individual capacity, 
and certainly not as speaking with authority on behalf of the Society, 
