HISTORY OP THE MICROSCOPE. 3 



two thousand years ago. We may besides advance a step 

 surther, and borrow from Seneca a passage whence the 

 same truth will emerge in a manner still more direct and 

 decisive. In the " Natural Questions " we read : " How- 

 ever small and obscure the writing may be, it appears 

 larger and clearer when viewed through a globule of glass 

 filled with water." 



Dutens has seen in the Museum of Portici ancient 

 lenses which had a focal length of only nine millimetres. 

 He actually possessed one of these lenses, but of a longer 

 focus, which was extracted from the ruins of Hercu- 

 laneum. 



At the meeting of the British Association, held at 

 Belfast in the year 1852, Sir David Brewster showed a 

 plate of rock-crystal worked into the form of a lens, which 

 was recently found among the ruins of Nineveh. Sir 

 David Brewster, so competent a judge in a question of this 

 kind, maintained that this lens had been destined for 

 optical purposes, and that it never was an article of dress. 



It is not difficult to fix the period when the microscope 

 first began to be generally known, and to be used for the 

 purpose of examining minute objects ; for though we are 

 ignorant of the name of the first inventor, we are acquainted 

 with the names of those who introduced it to public view. 

 Zacharias Jansens and his son are said to have made micro- 

 scopes before the year 1590 : about that time the ingenious 

 Cornelius Drebell brought one made by them with him 

 to England, and showed it to William Borrell and others. 

 It is possible this instrument of Drebell's was not strictly 

 what is now called a microscope, but was rather a kind 

 of microscopic telescope, something similar in principle 

 to that lately described by M. Aepinus in a letter to the 

 Academy of Sciences at St. Petersburg. It was formed of 

 a copper tube six feet long and one inch in diameter, 

 supported by three brass pillars in the shape of dolphins ; 

 these were fixed to a base of ebony, on which the objects 

 to be viewed by the microscope were placed. Fontana, in j 

 a work which he published inl646,says that he had made 

 microscopes in the year 1618 : this may be perfectly true, 

 without derogating from the merit of the Jansens; for 

 we have many instanced in our own times of more than 

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