178 POWELL AND LEALAND*S MICROSCOPE. 



moveable foot, in order that the principal weight may be over one of 

 the feet. When the person using it is standing, and the body of the 

 Microscope perpendicular, it is then firmest as taken from the case. 



A. The coarse adjustment for the body, which rests on two rollers, 

 and is moved by a rack and pinion. 



B. The fine adjustment, which is a screw with a cone, against which 

 there is a spring pressing against the cradle, which carries the com- 

 pound body. 



C. Milled head, which moves the stage to the right and left. 



D. Heads that move the stage at right angles to the other. (C) There 

 is one head on each side of the stage to this motion, in order that both 

 hands may be employed at the same time, one on C, and the other on the 

 opposite side, when a rotatory movement is required to search for ani- 

 malcules, or other objects. When the two screws, C and D, are used 

 together, a diagonal motion, and when separate, motions at right angles 

 with each other are obtained. 



E. Arm for holding the stops, F F F, which are used 

 when viewing opaque objects. To place them for use, 

 push down the mirror G to the extremity of the stem ; 

 put the stop into the spring-hole, turn it into the centre 

 of the stage, and raise it as high as the slide on which 

 the object is placed will admit of. 



G. Mirror for illuminating objects. When the concave side is used 

 it should be raised nearly to the stem, in order that the rays of light 

 proceeding from it may reach the object before crossing, for by this 

 means the most intense light is obtained. It is invariably used for 

 opaque objects, together with the Lieberkulm. At night it will be 

 necessary to use the larger condensing lens, which should be placed at 

 about its focal distance from the lamp, with its convex side to the mir- 

 ror, and adjusted till the rays of light fill it. 



H. Spring-piece for holding the slides on the stage. The most con- 

 venient mode of placing them is, to push up the spring-piece sufficiently 

 high to allow the slide to go on the stage, and then compress it until it 

 holds it. Any number of slides of the same width may then, after it 

 has been set, be put in without that trouble. Should the slides be very 

 wide, in order to have the whole range of the stage, it will be necessary 

 to observe if the centre of the slide corresponds with the line on the 

 centre of the stage ; if not it must be altered until it does. 



FIG. 2. Achromatic Condenser. This is adapted under the stage. It 



