128 SUMMARY OF CURRENT RESEARCHES RELATING TO 



until the whole object has been searched. The exact position of any 

 point may then be noted by the readings of 6 and a. If the frame is 

 transferred from one Microscope to another, the exact points at which 

 the screws g and Ji indent the sides of the stage, and the exact extent 

 to which g is screwed into its bearings must be noted. To facilitate 

 the latter adjustment, a small slit is cut across the threads of g. 



Professor Arendt, of Leipzig, writes to express his satisfaction 

 with the apparatus, which works extremely well in practice. The 



Fig. 11. 



slide can be inserted into the frame quite as easily as under the 

 ordinary springs, and marked points in an object are rapidly recovered. 

 He says, " For example, I have to-day searched a Bacteria-slide which 

 I had prepared, and found in it thirty-seven points of particular 

 interest. This was the work of about an hour. To find all these 

 points again occupied me only four minutes, and the adjustment is so 

 accurate that they were in every case brought back into the centre of 

 the field." 



Fig. 11 shows the apparatus in place on the Microscope. 



