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Wenham’s Prism of the binocular, with a side perforation 
opposite to which was a small silver reflector or a common 
thin glass cover, acting as a mirror and capable of adjustment 
to any angle — thus enabling it to throw the rays of light 
admitted by the side aperture through the object glass 
down on to the object itself. 
The disadvantage of this method is that all adaptors 
cause unsteadiness, and however skilfully constructed 
injure the accurate centering of the object glass, and while 
on the one hand the thin glass cover appears to produce some 
distortion of the image, the reflector so near the object 
necessarily casts off a number of the rays proceeding from 
it. This plan also seems to require lamp light and the use 
of a condenser. Messrs. Smith and Beck appear to have 
patented the use of the thin glass cover. 
Secondly, a modification of the foregoing by Mr. Dancer, 
of this Section, who places the thin glass or reflector between 
the eyepiece and the Wenham prism, cutting an aperture in 
the body of the microscope to admit the light. This dis- 
penses with the objection inherent to adaptors, and theoreti- 
cally seems the most perfect of these new methods ; but Mr. 
Hurst’s experience in its use was as yet too limited to form 
an opinion. He hoped however to report on the subject at 
the next meeting. 
Thirdly, that invented by Mr. Dancer, who places a 
circular mirror over the oblique tube of the microscope, 
previously removing the eye piece: the light is thrown 
down to the Wenham’s prism, and thence through the 
objective on to the object. The only disadvantage of this 
method was that of not admitting of binocular vision ; 
otherwise its simplicity, cheapness, and great facility of 
adjustment render it far 'preferable to the others, while its 
effects are fully equal to theirs. It answers moreover equally 
well by day or lamp light, and does not require a condenser, 
to be used. Mr. Hurst thought every binocular microscope 
