OF THE MICROSCOPE. 181 



side) and each of these small squares is designated by two 

 numbers, one of which indicates its position from bottom to 

 top, while the other marks its position from right to left. Thus 

 the square which lies on the tenth line from the bottom, and 

 the fifteenth from the right hand side, would be ] . Placing 

 on the stage an object mounted on an ordinary slide, with its 

 lower edge against a ledge of some kind, and its left hand edge 

 against a stop (the stop and ledge being movable as regards the 

 stage), we bring some particular spot into view. Removing the 

 slide, we now place the finder in its place, and read off the 

 double number. It is now evident that if at any future time 

 we should place the finder against the ledge and stop, and bring 

 the same number into view, then on removing the finder and 

 placing the slide on the stage, the precise spot originally under 

 examination will be in view. We can therefore easily register 

 anything of interest, and so be certain of finding it at any 

 future time. 



The finder cannot be used with microscopes fitted with clips 

 only. An object-carrier, provided with a ledge and stop, must 

 be used. Such object-carrier may either be the usual form of 

 the glass stage, or, with the plain stage, a thin plate of brass 

 with a hole in the centre, a stop at one end, and a ledge at one 

 edge, may be made to answer. 



Hitherto the Maltwood finders have been made only by one 

 firm in London. They are now made in this country, however, 

 very successfully. A dozen which we recently examined did 

 not vary as much amongst themselves as those obtained from 

 London. 



FINIS. 



