1048 RECORD OF CURRENT RESEARCHES RELATING TO 



bar // will be drawn in the same direction, and with it, of course, 

 the optic axis. 



This method of fine adjustment presents difiiculties in combination 

 with a rotatory stage, and for comparative micrometrical measurements. 

 The position of the milled-head at the lower end of the column is, 

 however, very convenient, as the hand rests on the table while 

 focussing. 



"Sliding" Objectives. — The Microscope shown in Fig. 117 

 (Parkes's " English Medical Microscope ") is provided with a '• patent 



Fig. 117. 



sliding adapter," for enabling the powers to be applied and changed 

 .very rapidly, without the loss of time occasioned by screwing. It is 



