266 
Notes. 
given, and indeed the author’s original paper is without illus - 
trations. 
Mr. Swift’s apparatus is a modification of a well-known form 
by Nachet. The object is viewed in the usual way, through the 
eyepiece ; the projecting box attached to the cap contains a 
prism, which reflects the image of the pencil and paper to an 
inclined tinted plate, where a second reflection directs the image 
upwards and renders it visible with the object. This instrument 
has the advantage of permitting the microscope to be used in 
any position. A second disc of neutral-tint glass can be inter- 
posed when the light from the object requires to be still more 
subdued to render the pencil point visible. 
In Dr. Russell’s instrument a tube ( a ) containing a right-angle 
prism (6) fits into the microscope. The image is reflected to a 
tinted plate (/), which again reflects it through the eyepiece ( e ). 
The tube (d) is prolonged downwards, and carries a telescopic 
c 
>p 
e 
% A 
I C ; fjr i 
a. 
9 
£1 
object-glass (g), which forms an image of the paper and pencil 
combined with that from the microscope. The image of the 
paper requires inversion, either by a reflecting prism (g) or suit- 
able lenses placed below the object-glass. 
Dr. Hudson, in the discussion which followed the reading of 
the paper, considered ruled squares placed in the focus of the 
eyepiece, the contents of which were copied on paper with simi- 
lar ruling, superior in simplicity and ease of working to any form 
of camera lucida, especially in the rapid drawing required when 
living objects were examined. 
Mr. Weber, by a simple variation of the hollow slide, has 
