place. Should the front of objective come in contact 

 with the cover glass or with the ring of cement on its 

 surface the tube must be elevated and the objective 

 focused. 



In the event of the objectives not being par focal, 

 the difference in their focal distance should be noted 

 for further use ; if little, by the amount of turn of the 

 micrometer screw, if considerable, by the extent of 

 adjustment required with the coarse adjustment. 



The method of procedure with the triple and 

 quadruple nose-piece is very much the same as with 

 the double, and the same rules will apply. In the case 

 of oil immersion 1-12 objective apply oil to the front 

 of objective before the nose-piece is screwed on the 

 tube, and if after use the nose-piece is left on the micro- 

 scope carefully wipe the oil from the objective. 



In case the coarse adjustment is by sliding tube 

 instead of rack and pinion elevate and depress the 

 tube by grasping the milled edge between the thumb 

 and forefinger, giving the tube a spiral motion. (See 

 page 50.) 



To Focus with Fine Adjustment. After the 

 focus has been found with the coarse adjustment the 

 fine adjustment should be brought into action, in order 

 to obtain a more sensitive and reliable adjustment for 

 focusing through the different planes or depths of the 

 object. Its range of movement is necessarily short 



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