18 THE MICROSCOPE. 



perfect of instruments. " These Microscopes," 

 says Mr. Quekett, speaking of those made by 

 our first-rate opticians, Koss, Powell, Smith, 

 and Beck, " approach, as far as we can judge 

 at present, the limits of conceivable perfection." 1 

 " The Microscope," says Dr. Carpenter, in his 

 elaborate treatise published in 1856, " has ac- 

 quired the deserved reputation of being one of 

 the most perfect instruments ever devised by art 

 for the investigation of nature." 2 Notwithstand- 

 ing these very positive assertions, we would be 

 exceedingly loath to forego the hopes which 

 Sir David Brewster allows us to cherish of still 

 higher progress towards perfection in the future 

 of the instrument. We may remember, for our 

 encouragement, that so late as 1821, M. Biot 

 regarded " the introduction of achromatic ob- 

 ject-glasses as out of the question, from the im- 

 practicability of making achromatic lenses as 

 small as those which the microscope requires." 3 

 But this object has been triumphantly attained. 



1 Quekett's Practical Treatise on the Microscope, p. 67. 

 - Carpenter's Microscope and its Revelations, p. 10. 

 ; Encydop. Brit. Art. Microscope, vol. xiv. p. 777. 



