14 MICROSCOPY FOR BEGINNERS. 



cost was to him lie knows only too well. To the young 

 student who longs for a microscope, I am almost tempt- 

 ed to say, if you cannot afford the cheapest suitable low- 

 power American objective, if you must have the ordi- 

 nary French triplet or none, take none. It is a hard 

 fate, but is not life itself hard ? Fortunately, however, 

 these inferior commercial lenses are not extensively in 

 the market at the present day. Yet the purchaser of a 

 microscope already fitted out with objectives, should 

 inquire whether he is buying French triplets. If so, 

 then as his experience, knowledge, and skill increase, so 

 will his dissatisfaction increase. An intelligent boy had 

 been using these poor lenses for some time, and doing 

 work that, under the circumstances, was commendable, 

 when he for the first time looked through a good low- 

 power (one-inch) objective. After a momentary exam- 

 ination, he glanced at me in a wondering way as he 

 said : " How beautifully bright and clear it looks ! My 

 microscope is different. I think it needs cleaning !" 



Modern objectives are the result of the most consum- 

 mate skill of the accomplished optician. There is no 

 chance work in his methods. Every curve is mathe- 

 matically exact, and is calculated and positively known 

 before the glass comes to the grinding-tool. Objectives 

 are usually a combination of several lenses, but the 

 union is not accidentally perfected. The maker's knowl- 

 edge of abstruse optics tells him the precise result to 

 expect from the combination of lenses of certain forms 

 made from glass of a certain chemical composition. He 



