576 
PROCEEDINGS OF THE SOCIETY. 
Now if it bo admitted that the condenser is a necessity of modern 
optical combination then it must be admitted that the condenser must be 
centered ; and if so, which is the better, to have a stand that will not 
admit of a centering substage, but requires that each piece of apparatus 
needing its axis brought into incidence with the axis of the optical 
combination of the objective and eye-piece must be separately and by 
great additional expense endowed with it, or to have a stand with a sub- 
stage that would admit of the centering of every condenser and other 
optical apparatus that might be employed ? 
There may, however, be those who would still affirm that with histo- 
logical and pathological mounts, for the study of which they were told the 
German instrument was adapted, it was not needful to obtain a critical 
image, or use a delicate condenser ; but he was convinced that there was 
a consensus of judgment amounting to unanimity amongst thoroughly 
skilled and experienced microscopists, that even students should employ 
high class and well corrected objectives, and it was simply absurd to 
suppose that they could get the best results with these without the 
employment of a suitable condenser. If this was so, he asked, was the 
Continental form the best adapted for its use ? This was only one point 
in connection with the subject, whereas he might have gone into ten 
points had time permitted. The author of the paper had spoken to 
them about the Continental form in which the body could be inclined ; 
true, in its modern and modified form it could be inclined, but they had 
only to try it in the horizontal position to find how uncertain was its 
equilibrium, and imperfect its lateral stability when so placed, if com- 
pared with that which he had before him, which was a tripod stand, and 
arranged with the best appliances for modern work. It was the simple 
Nelson model made in London, and could be produced as inexpensively 
as a Continental form of stand ; and while it was equally firm and steady 
in any position and at any inclination, it would admit of a finely finished 
substage with centering screws and all the essentials of a modern Micro- 
scope. Steadiness could be obtained in two ways, both of which they 
have illustrated in the two forms before them, one being by putting a 
great mass of lead into it and the other by ingenuity. If they looked 
to the stage of Continental form they saw it fitted with clips under 
which the slide was to be fixed, a plan entirely fatal to all accuracy of 
focusing when high powers were used. Why not leave it free as in this 
excellent arrangement of Mr. Nelson, enabling the slide or object to be 
manipulated as modern focusing requires ? He was not going to regret, 
however, that this paper had been read, and would only further add that 
he thought the Society was indebted to the author for giving them so 
fully what there was to be stated on the historic side of the question. 
JDr. P. M. Braidwood thought they had a most excellent appendage 
to the paper in the remarks they had just heard from Dr. Dallinger. The 
mention of the year 1824 reminded him of a Microscope which he had of 
about that date, and it struck him that they had been talking a great deal 
about the focusing and other arrangements, but had said very little about 
the lenses, which he thought were as good then as they were nowadays. 
With regard to Chevalier’s Microscopes, they were excellently good, 
especially as to the lenses, and it struck him that there was wonderfully 
little progress made in them since then. There might be a difference in 
