880 



RECORD OF CURRENT RESEARCHES RELATING TO 



Both stages arc applied to the ordinary stage, and arc held in 

 position by springs. 



The lirst stage (Fig. 05), which is the simpler of the two, 

 consists, 1st, of a fixed plate A, with a coiitral opening B for the 

 usual diaphragms, and, 2nd, of the movable plate C, which turns 

 about D, and lias a larger rectangular opening. 



On the plate C are two clamps E J*j, which serve to fix the slide. 

 A sector //' is attached to the fixed plate A, and is graduated at /'. 

 The pointer/ turns on II, and is connected at D with the movable 

 plate C by a screw, and the plate can therefore be moved about 

 the point I). As appears from a simi>le inspection of the figure, the 

 pointer/ (and with it of course the plate C) can bo turned about 11 



Fio. 95. 



so as to fall upon any particular division of the scale /'. The 

 preparation on the slide which is fixed by the clamps E E, can there- 

 fore be moved its whole width under the objective by means of the 

 lever movement at D, whilst the examination of the object longitudin- 

 ally is efiectod by gradually pushing the pointer / along the scale/'. 



If the motion of tlie i)oint(a'/ou the scalo/'is so regulated that 

 it moves each time over the space of the field of view, and if after 

 every such movement the pr(!2)aration is examined through its whole 

 width by turning the phito C about D, it follows that every point of 

 the object must appear in the field ; the ai^plicability of this stage as 

 a Maltvvood finder is also thus evident. 



To use the stage, for instance, for finding a given point (e. g. a 

 diatom-frustulo), it is only necessary to note the position of the 



