1 4 THE MICROSCOPE. 



results in new discoveries, were successively 

 made on the instrument ; Sir Isaac Newton 

 himself not deeming it beneath his transcen- 

 dent genius to lay down the Telescope, and turn 

 away from the contemplation of sun, and moon, 

 and stars, in order to use the Microscope for the 

 purpose of advancing it to greater perfection, 

 and of prosecuting the study of the minute 

 worlds which it revealed to the eye of man. 



8. But though the Microscope had been em- 

 ployed in the study of nature by many of the 

 most distinguished in the land for two hundred 

 years, and though important discoveries had 

 been made from time to time, the instrument, 

 as has been justly remarked, was little more 

 than "a scientific toy," until about the year 

 1820. Up to that period, two great difficulties 

 prevented the development of its powers. We 

 will attempt briefly to state these difficulties, 

 and to explain the methods employed for over- 

 coming them. Those who are even slightly 

 acquainted with the science of optics, are aware 

 that rays of light, transmitted through a lens, 

 are differently affected in the passage. Some 

 rays are more, some less, refracted. The rays that 



