260 HOW TO SEE WITH THE MICROSCOPE. 



founded, chosen to have abandoned the work on the 

 completion of the base, there would have been no time 

 lost or wasted ; per contra, had the base been but im- 

 perfectly measured, and the engineers proceeded to 

 build the other triangles resting thereon, they would 

 not long have continued in the service, but would have 

 been furnished with palpable reasons for leaving! 



Again, the question is ofttimes asked, do you require 

 that the observer shall be familiar enough with his ob- 

 jective as to work it up to the same force as its maker 

 could? Its the legitimate business of the optician, and 

 he can thus afford to spend his time on a matter which 

 to him is a necessity, but to demand this much of the 

 practical observer seems uncalled for. In answer to 

 this oft-repeated remark, we wish it distinctly under- 

 stood that it is eminently the business of the observer 

 to fully understand the practical woiking of his objec- 

 tives. The man who cannot make his object-glass per- 

 form as well as when in the hands of its maker, is using 

 an instrument that he does not fully understand, of 

 which the fact becomes incontestible proof. If it be 

 necessary that the optician be able to work an objec- 

 tive to its maximum, it is imperative that the micro- 

 scopist should do as much. Until this shall be the 

 case, absurdities will abound. Take for instance a con- 

 dition that often occurs. The microscopist orders a 

 new objective from the optician. The specifications are 

 complete, and the glass is made conformably thereto. 

 In due time the purchaser receives his glass, and can do 

 nothing with it, and it is returned in high dungeon to 



