1 2 THE MICROSCOPE. 



labours in the midst of the ruins of old Nineveh, 

 not the least singular was the discovery of a 

 plano-convex lens of rock crystal. "Its pro- 

 perties/' says the distinguished discoverer, 

 "could scarcely have been unknown to the 

 Assyrians, and we have, consequently, the ear- 

 liest specimen of a magnifying and burning 

 glass." 1 Seneca, in the first Christian century, 

 alludes to the magnifying power of a glass globe 

 filled with water, and thus rendering the smallest 

 letters of the alphabet larger and more distinct. 2 

 But at this time lenses of glass were chiefly 

 used as burning or reading-glasses, and it was 

 only about the beginning of the seventeenth 

 century that even the simple Microscope was 

 used to enter upon the field of those great dis- 

 coveries, which the more elaborate Compound 

 Microscope has effected in our day. 



As in many other cases, it seems now impos- 

 sible to name any one individual, to whom, 

 above his fellows, belongs the honour of invent- 

 ing the Single Microscope. Some claim it for 

 Roger Bacon, in the thirteenth century ; and 



1 Layard's Nineveh and Babylon, p. 197. 



2 North British Review, August 1 856. 



