THE MICROSCOPE AND ITS PARTS. 13 



French triplets. These are miserable lenses that should 

 always be shunned, as they will do the observer more 

 injury than much time can remedy. 



It is true that before the optician, especially before 

 the American optician, began to make really good ob- 

 jectives at moderate cost, these French triplets were 

 extensively used, and are said to have done some good 

 work. But at what expense ? Not at the expense of 

 any great amount of knowledge or skill in their manu- 

 facture, for the lenses were ground, mounted singly, and 

 then combined in an experimental way : two or three 

 were selected at random from a basketful, screwed to- 

 gether, and examined on a microscope. If the result 

 was considered satisfactory, all was well ; if not, one or 

 more of the lenses was replaced by others also selected 

 at random, and the experiments were continued until 

 the objective was considered passable and salable. 

 Such, at least, is the credible story. Their expense, 

 therefore, was not in the making ; it was in the imper- 

 fect image, in the great loss of light, in the injury to 

 the eye due to the strain caused by the absence of sharp- 

 ness and brilliancy characteristic of the image formed 

 by even low-priced American objectives, and in the time 

 wasted while unconsciously forming erroneous conclu- 

 sions from the objects so imperfectly seen. The writer 

 is somewhat emphatic on this point. He knows where- 

 of he speaks, for he began the use of the microscope 

 with French triplets, and employed them for years, be- 

 cause he was ignorant and had no teacher. What the 



