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PROCEEDINGS OF THE SOCIETY. 
It was now proposed to fill this by the election of Dr. G. B. do Toni, and 
he gave notice on behalf of the Council that the ballot for this purpose 
would be taken at the next ordinary meeting. 
The President said he wished to exhibit a lens which he had com- 
puted, of the loup type, giving a magnifying power of ten, but con- 
structed upon an entirely new formula. The working distance, as compared 
with Zeiss’s, was 60 per cent, greater, being no less than 8/10 in. 
He also exhibited a new achromatic aud aplanatic bull’s-eye condenser 
for use with the Microscope. He thought it was likely to be very useful 
to those who were doing any special work in photomicrography, or 
wherever a really achromatic parallel beam was required. 
Prof. A. E. Wright brought forward a method of measuring and 
counting microscopic objects. He was uncertain whether the method 
was a new one, but he had not seen it described, and he thought that the 
method was one which compared favourably with the micrometric methods 
which were described in the text-books, and which were ordinarily in 
use. The method consisted in projecting, by means of the substage 
condenser, a minified image of a scale or of a system of squares upon 
the plane upon which the microscopic objects were disposed. 
By means of diagrams which were drawn upon the blackboard, it 
was explained that the scale or the system of squares could be placed in 
any one of the three following positions : — (a) On a glass plate (or on 
the window), which was interposed between the source of light and the 
plane mirror; (6) on the surface of the plane mirror; or (c) on a plate 
interposed between the plane mirror and the substage condenser. Under 
any of these circumstances it was shown that the image of the scale 
could, by proper focusing of the condenser, be superposed upon the 
microscopic object. 
It was suggested that this method of projecting a system of squares 
upon the microscopic preparation might be employed with advantage in 
the enumeration of red blood-corpuscles. The employment of this 
method would obviate the necessity for the micrometric ruling on the 
bottom of the haemocytometer cell. 
It was further shown that the proposed method of mensuration pre- 
sented advantages over the methods of mensuration which are at present 
in use, inasmuch as the value of the divisions of the scale did not vary 
with the magnification which was applied, but was a constant so long 
as no change was made in the relative positions of the Microscope and 
the scale. The value of the divisions of the scale could thus be deter- 
mined once for all for a particular Microscope, comparing them with 
the divisions of a stage micrometer. 
It was further explained — first, that the same scale, if set up at 
different distances from the Microscope, could be made to give either 
large or small micrometric divisions ; and secondly, that the foreshorten- 
ing of the interspaces between the horizontal divisions could readily be 
corrected for by disposing the glass plate upon which the scale was 
inscribed in a plane exactly parallel to the plane of the mirror. 
