6 HISTORY OF THE MICROSCOPE. 



the instrument, its appearance was necessarily obscure and 

 indistinct. Lieberkuhn adapted a separate microscope to 

 every object : but all this labour was 

 not bestowed on trifling objects ; his 

 were generally the most curious ana- 

 tomical preparations, twelve of which, 

 with their microscopes, are deposited in 

 the Museum of the Royal College of 

 Surgeons. 



Lieberkuhn's instrument, fig. 1, is 

 thus described by Professor Quekett -, 1 a b 

 represents a piece of brass tube, about an 

 inch long and an inch in diameter, which 

 is provided with a cap at each extremity ; 

 the one at a carries a small double -con vex 

 lens of half an inch in focal length, whilst 

 the one at b carries a condensing lens three- 

 quarters of an inch in diameter. 



A vertical section of one of these instru- 

 ments is seen in fig. 2 : a represents the mag- 

 nifier, which is lodged in a cavity formed 

 partly by the cap a, and by the silver cup 

 or speculum I. In front of the lens is the 

 speculum Z, which is a quarter of an inch 

 thick at its edge, and whose focus is about 

 half an inch ; in front of this again there is 

 a disk of metal c, three-eighths of an inch in 

 diameter, connected by a wire with the small 

 Fi s- J - knob d ; upon this disk the injected object 

 is fastened, and is covered over with some 

 kind of varnish which has dried of a hemispherical figure. 

 Between this knob and the inside and 

 outside of the tube there are two slips of 

 thin brass, which act as springs to keep 

 the wire and disk steady. When the 

 knob is moved, the injected object is 

 carried to or from the lens, so as to be in 

 its focus, and to be seen distinctly, whilst 

 the condensing lens b serves to concen- 

 trate the light on the speculum. To tho 



Micro- 



icope. 



(1) Practical Treatise on the Microscope, p. 16. 



