riioTOMicRocR.triiy .i.\n tv.ciisic.u. microscoi'Y in,; 



ijriMt prt-risiDii. Tlu- somi-.i|)<Kliri)iuatic ohjirtives contain fluorilc 

 c'li'iiicnts anil ihi-so objectives occupy a position in (|uality intcr- 

 tuetUate l)et\veon the achromatic and apochroniatic types. 



Objectives are classilieil and listed according to llieir optical char- 

 acteristics such as primary ma^nitication, numerical aperture and 

 focal leni;th and as to whether they heloiijj to the "ilry" or the "iin- 



gfTtfurt 

 fIffffSf 



Fig. 5 — A battcrj- of medium and high-power objectives jnd eyepieces. 



mcrsion" series. The term "dry" signifies that the objecti\c when 

 properly used is separated from the specimen by a stratum of air. 

 In the case of the immersion objectives some one fluid for which 

 medium the objective has been computed, such as water, glycerine, 

 cedarwood oil, etc., is used to connect the front lens of the objective 

 with the specimen. The fundamental difference between the dry 

 and the immersion objectives is one of resolution, where by resolution 



