ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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a left-handed one, therefore the movement of the noso-piece follows the 
apparent movement of the screw. In other words, when you think you 
are turning the screw downwards you are in reality raising it, and by 
doing so you are lowering the nose-piece. 
This plan removes tho single objection to tho Powell plan of fine- 
adjustment, viz. the reversal of the movement, which is confusing until 
the idea is overcome by practice. 
I have brought this to the notice of tho Society, as I feel sure they 
have no wish to disparage any instrument which may be brought before 
them by an erroneous criticism founded on a misconception of its con- 
struction.” 
Nachet’s Hand-Microscope. — This instrument, shown in fig. 5, is 
intended for circulation amongst an audience. Contrary to the usual 
arrangement in Microscopes, the preparation is held on its upper surface 
Fig. 5. 
by the stage in such a way that the different preparations are at once 
brought into focus when this has been regulated once for all. For 
finding the point of the object which it is required to demonstrate, the 
instrument can be adjusted on a base-plate, and can be separated again 
for circulation amongst the audience. 
Nachet’s Movable Stage. — In this stage, represented in fig. 6, two 
carriers, perpendicular to one another, move the preparation in all 
1893. H 
