114 PROCEEDINGS OF SOCIETIES. 
Mr. WenHam.—Upwards of five years ago Mr. Hewitt suggested 
to me, and I believe to others, the principle of making an object- 
glass its own illuminator. I immediately gave the mode a trial, 
and I have here the reflector by which the experiment was made. 
It is a brilliantly polished speculum, with an aperture in the centre 
just sufficient to admit the pencil of rays from the object-glass. 
This I placed obliquely in the axis of the microscope, through 
the side of which was an opening for admitting the light from the 
illuminating source, and the rays from the object returned through 
the central hole. I got an extraordinary amount of light, but the 
internal glare was so great that I found it had obscured the 
object, which had a kind of fog thrown over it. Consequently I 
abandoned the trials. I informed Mr. Hewitt of the result. Mr. 
Beck informed me at the last meeting that the light might be too 
brilliant. He said that the partial reflection from the single disc 
of glass is of the proper degree of intensity, and that with the 
speculum, I did not make use of the most valuable or central 
portion of the rays. With a piece of plain glass! it is known that 
the more oblique the incidence the greater the light reflected. 
On asking the question whether this might be put at a more 
oblique angle than 45°, he said that generally that did not answer, 
the light being over-abundant. Then, as regards the question of 
the application of a thin disc of glass for illuminating an object, 
that is an eld idea. I have in my hand a micrometer eye-piece 
made by Troughton and Sims for a telescope in which the same 
plan is employed for illuminating the cross wires, and it is used 
to the present day. Mr. Wenham exhibited the eye-piece, and 
explained that the light was thrown in sideways upon a dise of 
glass, which, of course, must be perfectly ground and polished; the 
light is then thrown downwards on the wires. The first piece of 
glass was to prevent the access of dust. 
The Presipent.—I know this quite well. 
Mr. Weyuam.—lI do not wish to disparage the idea at all, for, 
in my opinion, it removes a difficulty against which we have been 
labouring for years, in attempting to illuminate an object with 
high powers, where it is almost in contact with the front lens. 
Mr. Stacx.—I have had the opportunity of trying the ilumi- 
nator of Messrs. Powell and Lealand, and also that of Mr. Beck. I 
have not had the opportunity of trying (although Mr. Lobb was 
kind enough to show it to me) the one devised by Mr. Smith, of 
America. On reference to ‘Silliman’s Journal,’ it will be found 
that Mr. Smith speaks of using glass to reflect the rays of light 
downwards. The meaning of the passage is not very clear; but 
he says that the result of using the glass covers was that he did 
not get sufficient relief; that the field looked too flat, which was 
not the case when he used the small silver mirror. His allusion to 
using several thin discs is rather puzzling, because it is not to be 
supposed that he placed his one behind the other, and thus 
created ‘a confusion of reflections. Mr. Slack then suggested 
that Mr. Lobb should state his opinion of the silver reflec- 
