98 Transactions of the Society. 
things, not from that of the optician. All matters of scientific optics 
•will doubtless be dealt with by my successor, who is far more compe- 
tent to do so than I am. The optical construction of a Microscope 
has made vast strides during the last few years, and although I am 
not one of those who believe that perfection has been reached, or even 
approached, or that there is not any field left for improvements in the 
future, yet it must be admitted by all impartial minds which have 
been occupied with the subject that such field has been substantially 
diminished ; and it is also indisputable that the perfecting — or rather, 
improving, for nothing is perfect — of the optical combinations of a 
Microscope is by far the most important part of its construction, and 
has rightly claimed the greatest share of attention. But I am not 
sure that, while eagerly pursuing this subject of paramount impor- 
tance, and while rejoicing in such brilliant discoveries as homogeneous 
immersion and apochromatic lenses, we have not somewhat neglected 
other parts of the instrument, which might very well receive atten- 
tion in the lull after these great optical successes. It must be 
remembered that the finest gem is half wasted if badly set, and it 
must also be borne in mind that the perfecting of these lenses is 
only a means to an end ; that end is not only the examination of test 
objects and of objects requiring the highest powers of the instrument, 
nor of show objects; these are all matters of great value and of 
the highest interest ; but behind them is the supreme necessity of 
enabling the thousands of scientific workers who now use the Micro- 
scope as their everyday instrument of research to do their work in the 
best, the most convenient, and the quickest manner possible. Another 
element for consideration is that a large number of these investigators 
are not men of large means, who can afford to be continually pur- 
chasing new and expensive apparatus ; if they make an effort to buy 
it, it must wear well. Now I think that in the race for optical 
excellence and for low initial cost, the importance of some of these 
points has not been kept as rigidly before the eyes of makers and 
designers of Microscopes as it might advantageously have been. The 
first instance which I will refer to is the coarse-adjustment. This is 
of the highest importance, for it is used by the average of workers 
far more than the fine, and it is manifest that the most perfect optical 
arrangements are wasted if the coarse-adjustment of the instrument 
which supports them will not hold its focus. When our Microscopes 
come home from the makers’ hands they usually do hold their focus, 
and the coarse-adjustment works admirably ; but do they continue to 
do so ? My experience is that, as a rule, they do not. I am the 
possessor of several Microscopes, and my instruments are not put 
away in a glass case to be looked at or preserved ; they are pretty 
constantly used ; there is only one of them with which I have not 
had trouble over the coarse-adjustment, and that one is the oldest of 
them all, and has had quite equal work with the others during the 
shorter period they have been used in. I will not mention instru- 
