MEMORANDA. 



167 



This consists of two scales ; one of them, the vertical, A, 

 is attached to the main bed-plate of the stage ; the other, 



or horizontal one, B, is attached to the arm carrying the 

 pinion which works the vertical stage. These scales are 

 made on thin paper, and on examining a Ross's microscope, 

 it will be found that there is ample room for each stage to 

 work over its respective scale. The horizontal scale B is 

 carried on a little way, and fixed on the plate of the vertical 

 stage, as well as to the arm before mentioned. 



The only thing else required is a small brass stop, fixed on 

 the sliding plate at G. This is for the slides always to 

 abut against ; and also two little pegs, or stops, at D D ; these 

 are fixed into the revolving plate, and are for the sliding plate 

 to abut against. These three stops are removable at pleasure. 



The mode of using the finder is obvious : — If, for instance, 

 I am about to examine a slide of any tleposit, for diatomes, 

 I place it on the stage, close up to the stop G, and bring the 

 sliding plate down on the stops D D, and set the revolving 



