290 E AMBLES OF A NATURALIST. 



at the object which he wishes to examine. The second 

 may be considered as a combination of two lenses, one of 

 which, the object-glass, serves to produce in the body of 

 the instrument an image which is received by the other 

 (the eye-piece), which transmits it to the eye. In the 

 compound microscope, the observer, properly speaking, 

 does not look at the object itself, but at the image of the 

 object. 



Simj^le microscopes, or, to speak in more general terms, 

 magnifying glasses, appear to have been known to the 

 ancients ; at least, among the engraved stones which 

 have come down to us from Greek or Roman artists, 

 there are some in which the truly microscopical details 

 cannot be seen by the naked eye, and it is therefore very 

 difficult to suppose that they could have been executed 

 without the employment of some auxiliary agent. It 

 mio-ht, however, be suggested that the ancients made use, 

 for the purpose, of simple glass spheres, filled with water, 

 similar to the one which Seneca employed to read small 

 and indistinct written characters. 



Soon after the invention of spectacles, that is to say, 

 towards the beginning of the fourteenth century, it would 

 at all events appear that lenses, properly so called, were 

 fabricated, and that attempts had been made to render 

 their mao-nifying powers more considerable. All the 

 early micrographers used simple lenses, which, as in 

 the case of Leuwenhoeck, they frequently fabricated for 

 themselves ; and the splendid discoveries of Malpighi *, 



* Malpighi, a celebrated Italian physician and anatomist, was 

 born in the neighbourhood of Bologna in 1628 ; after having been 

 Professor of Anatomy at the University of that city, he successively 

 filled the same post at the Universities of Pisa and Messina' 

 Having been called to Rome as physician to Pope Innocent XII., 

 he took up his abode in that city, where he died in 1 694. Mal- 

 pighi may be considered as one of the founders of Comparative 

 Anatomy and Experimental Physiology. 



