36 



PRACTICAL PHOTOMICROGRAPHY. 



matic substage condenser. Indeed, condensers are frequently 

 mounted so as to carry all or several of the accessories described, 

 and to carry them all at once ; while the writer admits the 

 ingenuity, and even the occasional convenience of such 

 arrangements, he hardly ventures to recommend their use. 

 Arrangements of this kind are apt to be heavy, clumsy, bulky 

 and puzzling, and it is on the whole better to have on the 

 substage at the time of work only as many of these accessories 

 as are actually in use. Still it may suit some tastes and some 

 purses to adopt one of these multiplex arrangements, and one 

 is figured here as a sample of the usual article. 



FIG. 7. A FITTED SUBSTAGE CONDENSER ACHROMATIC. Swift. 



Another common contrivance for facilitation of work and 

 for convenience of manipulation is a nose-piece, double, triple, 

 or even quadruple (Fig. 8). While admitting the convenience 

 of this contrivance the writer does not recommend its use, for 

 delicate work at all events. The less load we have on the 

 microscope tube, especially near the objective, the better; 

 cases have occurred of injury to the working of a delicate fine 

 adjustment screw by a heavy nose-piece. Greatly to be 

 preferred for efficiency and for economy, and not a whit behind 



