JOURNAL 
OF THE 
ROYAL MICROSCOPICAL SOCIETY. 
MAECH, 1878. 
I.— THE PEESIDENT’S ADDEESS. 
H. C. SoRBY, F.E.S., P.G-.S. 
Plate I. 
When first I commenced to write an address for this evening, I 
intended to call your attention chiefly to some special subjects 
which have been prominently brought before our Society during 
the last year or two. I never contemplated entering into certain 
questions with which I am so little acquainted practically that it 
would be presumptuous to express any confident opinion of my 
own. I thought it would be far better to enter at greater length 
into the consideration of such special subjects as I have studied 
sufficiently as to he able to treat them in a more or less original 
manner. I proposed to lay before you an account of some further 
observations of my own in connection with the visibility of very 
minute objects, and to discuss what has been done and said by 
others in relation to this subject ; and also to consider some points 
in the construction of object-glasses, which have more particularly 
attracted my attention during the last few years. However, when 
I came to write out only a superficial account of another subject, I 
soon found that it alone was even more than enough to occupy 
your attention this evening. Being an almost entirely new appli- 
cation of the microscope, I thought it sufficiently suitable for the 
present occasion, and that it would be better to treat of it in some 
detail, rather than say so little as to make it scarcely intelligible, in 
order to find room for several other subjects. I propose, therefore, 
now to describe some simple additions to the microscope, which 
DESCRIPTION OF PLATE I. 
Figs. 1 to 6 represent the images of a small circular hole, viewed with a 
microscope through various crystals. 
Figs. 7 and 8 are diagrams of mounted objects. 
Figs. 9, 10, and 11 show the appearances seen on viewing the cross lines of the 
grating through different crystals. 
VOL. I. 
B 
