404 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



in the sliding objective changer to the substage fitting, and found this 

 enabled him to get an easy and rapid change of condensers. The scheme 

 consists of a metal slide, ~l\ x 1 \ in., with bevelled edges, on which the 

 condenser is mounted, and, when necessary, a throw-out arm for stops, 

 and an iris-diaphragm. Two D-shaped metal plates, the flat sides of 

 which are set 1\ in. apart, form a groove for the slide to work in. 

 These plates are screwed to a metal collar, the diameter of which is such 

 as to allow the slide-condenser changer to be fitted to any Microscope 

 that has a substage made to the R.M.S. gauge. 



Fig. 40 shows a plan of the slide-changer in position, while fig. 41 



Fig. 41. 



gives a sectional elevation along the line AB (fig. 40). When three or 

 more condensers are used it is desirable to have each mounted on a 

 separate slide ; but when only two condensers are used, one slide may be 

 sufficient, as the optical parts can be made interchangeable. When the 

 slide with condenser has been pushed home, a screw, working through 

 one of the plates, holds this firmly in position. This changer does away 

 with the necessity of a throw-out substage, and any variation of centrality 

 in the condenser can be adjusted by the centring screws in the regular 

 way. To rack down the substage fitting, withdraw, and insert a new slide, 

 are all the movements that are required to obtain a change of condenser, 

 and this can be effected as readily as a change of objective on a revolving 

 nose-piece. 



