OBJECT GLASSES. 99 



ft is neither the only nor yet the chief work of the 

 microscope (as some appear to suppose) to resolve the 

 markings of the siliceous valves of the diatomacea ; in 

 fact the interest which attaches to observations of this 

 classier se, is of an extremely limited range. . . . 

 And the more carefully we look into the history of 

 those contributions to our knowledge which have done 

 the most to establish the value of the microscope as an 

 instrument of scientific research, the more clear does it 

 become that for almost every purpose except the resolu- 

 tion of the diatom tests, objectives of moderate angular 

 aperture are to be decidedly preferred." * 



This quotation -essentially true when first published 

 has been, and to a considerable extent now is, the 

 orthodox faith ot the microscopist. It has been en- 

 dorsed by everybody, both at home and abroad; the 

 world of observers have rested peacefully at ease on its 

 broad platform; the man of science was serene and 

 content with his medium apertures; but it was the 

 crowning glory of the quack that a " good hcnest," 

 low-angled, " working" triplet cost only a dollar or 

 two. Adid it was a fact, that so far as faith was con- 

 cerned, the scientist and the veriest quack were in the 

 same boat together, and both found pleasure in endors- 

 ing the teachings of Dr. Carpenter. 



It seems to me that this singular state of things can 

 be easily accounted for. The hard-working investiga- 

 tors had little opportunity to study object-glasses, their 

 time being completely occupied, and their eyes sorely 



*"The Microscope and Its Revelations" fifth edition, 18Y5, page 204. 



