112 
PROCEEDINGS OF THE SOCIETY. 
objective, intended as a low power for use in examining living objects in 
water. The instrument was used in a cylindrical glass vessel, at the 
bottom of which the objects were placed, and prevented from swimming 
out of focus by a cover-glass placed over them and resting on some glass 
supports ; more water was then poured into the vessel, and the Microscope 
objective inserted in the water. The definition was exceedingly sharp. 
The second was a new appliance by Messrs. Zeiss, an adaptation of 
the Porro prism to the Microscope, providing an erector which would no 
doubt be found useful for dissection and other purposes. The third was 
a Binocular Microscope made by Leitz, sent for exhibition by Messrs. 
Watson and Sons. It consisted of two Briicke lenses fixed upon a bar 
in such a way that their axes were inclined towards each other at an 
angle so as to meet at the focus, their attachment being jointed so that 
the distance between the two tubes could be altered to suit the eyes. 
This was a very ingenious arrangement, and one which was likely to 
prove very valuable for low-power examination of large objects, or for 
low-power dissection. 
The President said they had passed a vote of thanks to Mr. Curties 
at their last meeting for the loan of the instruments and exhibition of 
high-power objects, but he should like to say how much he was surprised 
on looking round after the meeting, to see such an exhibition of apo- 
chromatic objectives and valuable slides as that which was provided on 
that occasion. He thought it was the first time there had been a public 
exhibition of so many valuable objectives and objects. 
Mr. Keith Lucas exhibited a new model Microscope, the design of 
which was to effect both coarse and fine adjustments by means of a 
single slide, and thereby to reduce the expensive work of jdaning. This 
was effected by means of a compound lever, a large wooden model of 
which was also shown. 
The President, in expressing the thanks of the Society to Mr. Lucas, 
said it would be scarcely possible for anyone to make remarks upon this 
method of construction, as no one had yet seen it. The idea, however, of 
bringing a large model of it was, he thought, an excellent one for 
enabling them more easily to understand how it worked. 
The President said, as there was no formal paper on the Agenda for 
the evening, he would call attention to some of the various types of 
Binocular Microscopes which were being exhibited. Amongst these 
would be seen the Ahrens binocular eye-piece for Microscopes, in which 
both tubes were equally inclined ; one by Murray and Heath, in which 
there was one straight tube, the construction being something like that 
of Nachet. The Stephenson binocular was there in several patterns, and 
also one by Leitz. Special attention was directed to the form exhibited 
by Messrs. Zeiss made with the Porro prisms, and giving an erect 
image ; this Microscope was provided with two objectives of equal power, 
one for each tube, and the binocular effect was very remarkable and 
beautiful, the stereoscopic impression of solidity being far greater than 
anything of the kind obtained by a divided image from one objective, 
