ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



649 



MICKOSCOPY. 

 A. Instruments, Accessories, etc.* 



(1) stands. 



Lieberktihn Simple (or Compass) Microscope. — This handy 

 Microscope, presented by ]\Ir. Alpheus Smith (tig. 119), was invented 

 about 1738, and was intended principally for viewing opaque ol)jects, 

 which were illuminated by a silver speculum in the centre of which is 

 mounted the bi-convex lens. This useful contrivance has endured to 

 the present day and forms an essential part of the outfit of every com- 

 plete Microscope. It was first figured by P. van Musschenbroek in his 

 Essai de la Physique, published at Leyden in 1739, and was then made 

 with various modifications by all English makers of the period until the 

 end of the eighteenth century. Henry Baker figures and describes it in 

 1740 and calls it " The Single and opaque Microscope," and it is found 

 in the works of George Adams 1747-87, Benjamin Martin 17G0, and 

 others. 



The silver concave mirror for the illumination of opaque objects is 



Fig. 119. 



usually ascribed to Dr. N. Lieberkiihn, but it must not be forgotten 

 that Descartes in 1G37 figured an appliance embodying the same prin- 

 ciple, though it may not have been practically applied at that early date. 

 The present model is of superior make and in exceptionally fine con- 

 dition ; the maker's name is not indicated, but by comparing various 

 small details of parts and ornaments I have come to the conclusion that 

 the maker was John Cuflf and its date about 1745-50. 



* This subdivision contains (1) Stands ; (2) Eye-pieces and Objectives ; (3) 

 Illuminating and other Apparatus ; (4) Photomicrography ; (5) Microscopical 

 Optics and Manipulation ; (6) Miscellaneous. 



