THE MICROSCOPE. 



15 



Lieberkuhn himself exhibited his microscopes to some Fellows 

 of the Eoyal Society of London in 1739. 



The solar microscope, as improved by Mr. Ouff, for a 

 length of time created great wonder and astonishment; it 

 was principally used for the exhibition of animalcules, and the 

 circulation of the blood in the newt, frog or eel; and was 

 also recommended for getting the exact figure of objects on a 

 large scale, the image being received upon a screen of paper, 

 on which the outline was traced either with a pen or pencil ; 

 when the paper was sufficiently thin, the artist, standing 

 behind the screen, was enabled to draw the image much 

 better than when standing in front of it, and with this great 

 advantage, that the shadow of the hand did not interfere with, 

 or obstruct, any portion of the light. 



By far the most useful of Lieberkuhn's microscopes, how- 

 ever, was the one for viewing opaque objects, by means of which 

 he made so many important discoveries in 

 the minute structure of the mucous mem- 

 brane of the alimentary canal, as to im- 

 mortalize his name. The most simple 

 form of this instrument is represented by 

 fig. 11 ; it is not unlike the pocket micro- 

 scope of Wilson, represented by fig. 9, 

 being also held in the hand by the handle, 

 ^; a is a flat piece of brass attached to 

 the handle, JO, it supports the lens holder, i, 

 and through it passes the screw, b, which 

 is connected to the back-plate, c; a spring, 

 e, keeps the plates a, c, apart, and the nut, 

 d, adjusts the lens to the focus of any 

 object placed either on g or h. But the 

 chief point of merit in its construction 

 consists in a concave speculum of silver, k, 

 highly polished, to the centre of which the 

 magnifying glass, /, is adapted ; this being 

 screwed into the ring, i, and the object 

 being fixed upon the point, ff, or held in 

 Fig. 11, the forceps, h, the instrument is placed 



