ZOOLOGY AND BOTANY^ MICROSCOPY, ETC. 



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The rectangular plate (at the lower part of figure) is attached to 

 the stage of the Microscope by the usual spring clip, and is adjusted 

 so that a cell is in the field of view. The upper, circular, tablet — in 

 the openings of which the cells are placed — can then be rotated, and 

 the contents of the whole sixteen cells passed in review. 



For public exhibition, at soirees, &c., this rotating holder will be 

 found very convenient. It is very light, and not easily injured. 



Wallis's Calotte Siibstage. — At the December meeting, Mr. G. 

 Wallis exhibited a Microscope of his own design and construction, 

 the chief novelty of which was the substage, shown in Fig. 16. 



The substage is formed of a strong brass calotte, upon which 

 Mr. Wallis applies (1) a silver side reflector (shown on the right of 

 the figure), (2) an achromatic condenser with its system of diaphragms, 

 (3) a paraboloid, (4) a dark well, (5) a clear opening for use without 

 special apparatus. On the in- 

 side of this calotte a section of Fig. 16. 

 another one is mounted to rotate 

 on the same centre, and carries 

 selenites and ground and tinted 

 glasses, and similarly a third 

 carries the polarizer ; so that 

 either or both can be rotated 

 and used beneath the achro- 

 matic condenser. The whole 

 is mounted on a pinion at an 

 angle of 45° on a substage arm 

 (moved by rack and pinion), so 

 that the rotation of the outer 

 calotte figured will bring each 

 piece of apparatus into the axis 

 of the Microscope, where a 

 spring stop holds it. A fixed 

 washer between the plates pre- 

 vents the motion of the one 

 being communicated to the 

 others, each acting independ- 

 ently. 



Mr. Wallis claims that in 

 this manner all the substage 

 apparatus usually adapted to 

 the Microscope can be carried 



ready for immediate service, thus dispensing with the trouble of 

 applying each separate accessory whenever required. He uses a 

 similar calotte nose-piece carrying sundry objectives, and states that 

 he leaves all his apparatus thus attached to the Microscope in constant 

 readiness for any investigation he may desire to make. 



Centering Nose-piece as a Substage. — Mr. E. M. Nelson has 

 suggested that for use on small Microscopes, the ordinary centering 

 nose-piece can be easily applied as a substage (see Fig. 17), thus pro- 



