30 
The President’s Address. 
that their increased development was not usually a matter of 
much pathological significance. 
With regard to matters relating to the practical adaptation 
to the microscope, or improvement in apparatus, we have to 
notice Dr. Maddox’s “ Slide-clip” for holding on glass covers, 
either at the time of mounting or during temporary observa- 
tions. This contrivance is simply made from a piece of brass 
wire. 
At a subsequent meeting, a different form was explained by 
Mr. J. Hogg, as manufactured at a very small cost per dozen 
by Mr. Baker. One of the prongs of this clip is armed with 
a small disc of cork, and the opposite one is turned in the 
form of an open ring, through which the proper position and 
arrangement of the object may be seen. These clips will 
unquestionably be found to be of great service in mounting 
objects, and maintaining a pressure till the object is dry 
or the medium properly set. 
Next in order, is a form of adjustable diaphragm by Mr. 
S. Kincard. This consists of a very thin piece of vulcanized 
india-rubber tube set in a brass mounting so as to admit of its 
being twisted. In this operation every portion of the cir- 
cumference of the tube, midway between the ends, gradually 
approaches towards the axis, and forms a variable aperture 
sufficiently uniform in outline. But the possible objection to 
this may be that the aperture is too far below the condensing 
lens, thus making it produce as much an effect of reduction 
of light as of diminished aperture. 
Among other instrumental objects that have been brought 
before us is an ingenious leaf-holder and revolving disc- 
holder, by Mr. Smith, and an adjustable diaphragm eye-piece 
by our Secretary, Mr. Slack : this was devised for the pur- 
pose of limiting the extent of the luminous field, so as to suit 
the shape of any object through which it was desirable to 
transmit a strong light. By shutting out all extraneous or 
useless light, and admitting that only which comes from the 
object or part of the object under view, it is evident that we 
can see delicate structures far more correctly and comfortably 
than when surrounded with a large field of bright light that 
almost blinds us. This diaphragm can be arranged so as to 
enclose an object of irregular figure, and it will also serve as a 
pointer, as the aperture may contain only that portion of the 
object required for demonstration : the arrangement is neatly- 
fitted into an ordinary eye-piece, and in no way interferes 
with its general use. 
The most important improvement in the year relates to 
new forms of binocular microscope, by means of which the 
