W. T. SUFFOLK ON DELINEATING MICROSCOPIC OBJECTS. 185 



Soemmering' s mirror I have never used, and cannot, therefore, 

 speak of it from experience. Tinted reflectors are pleasant to work 

 with, but reverse the image, and it is necessary to use a reflecting 

 prism for the completion of the drawing. They are not available 

 for the binocular instrument on this account. 



Wollaston's camera lucida, on account of its double reflectors, 

 does not reverse the image. It is rather troublesome to use on 

 account of the constrained position of the eye, but it is indispen- 

 sable when a drawing is to be highly finished, especially with the 

 aid of the binocular. 



Finding the horizontal position of the microscope troublesome, 

 inasmuch as it disturbed the illumination used for observation, I 

 thought that the old principle of enlarging and reducing drawings 

 by squares might be applied to microscopical purposes. Messrs. 

 Beck supplied me with a ruled disc to be placed within the eye-piece 

 in the focus of the eye-glass, so that the field appeared to be ruled 

 in squares, and which very much facilitated the taking of a sketch, 

 by merely using a paper ruled in squares of a convenient size. 

 This process is, to a person used to drawing, much more convenient 

 than any of the other processes, as it in no way hinders the arrange- 

 ment of the instrument or its illumination. 



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