CHAS. LENTZ & SONS 
Camera Cucidas 
No. 2112. Abbe Camera Lucida, as applied to Microscope Tube 
Prism carrier shown in outline thrown back as when not in use 
2112. Abbe Camera Lucida, New Improved Form $20 OO 
This Camera Lucida presents a number of important im- 
provements over the older forms, although the optical principle 
remains the same, viz.: The image of the paper and pencil point 
is superimposed upon the image of the object by means of an 
adjustable mirror and an Abbe's Prism, so that the object and 
pencil point are seen together. 
The Abbe Prism is mounted in a cylindrical closed box, so 
constructed that it may be rotated about an axis, thus bringing 
the prism over the eyepiece of the microscope (which position 
is indicated by a pronounced click), or carrying it entirely out 
of the way of the observer. 
In using the Camera Lucida, it rarely happens that the 
proper relative illumination exists between the drawing paper 
and the object, owing to the varying amount of light transmitted 
by objectives of different foci. With high-power objectives, the 
paper is apt to appear too bright and thus drown the image of 
the object, the reverse occurring with low powers. 
To correct this difficulty,, a series of moderating glasses is 
arranged to rotate between the prism and the mirror and between 
the prism and the objective, being operated by the knobs shown 
at the side of the prism carrier. By means of the two sets ot 
glasses a perfectly clear image of both pencil point and object 
is obtained with any combination of eyepiece and objective. 
The whole prism arrangement is provided with a centering 
device, acting on the axis of the prism carrier and moved by 
two milled heads conveniently placed. By this device the prism 
may be centered to the eye lens of the microscope, thus secur- 
ing equal illumination and sharp definition over the entire field. 
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