ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 



1053 



Fig. 222 



are two cams, one on the left and the other in front, and they are 



actuated by large milled heads beneath the stage. Two spiral springs 



on the projecting rods press the stage plates 



against the cams. A very smooth motion 



is thus obtained. The spring clips are 



raised by the milled head on the left 



against the action of a spiral spring which 



is wound on the axis, and they provide 



an unusual depth of space for cells or 



other thick objects. The stage was more 



especially intended for use with a photo- 



micrographic camera. 



Electric Incandescence Lamp. — This, 

 fig. 222 (received anonymously from 

 America), is a very convenient form of 

 incandescence lamp for use in the sub- 

 stage. The glass receiver with the carbon 

 filament and the wires for connecting 

 with the battery are screwed into the sub- 

 stage adaptor shown in the fig., from which 

 they are, however, insulated by ebonite. 

 Over the glass receiver fits a piece of 

 tubing (shown at the side), which carries 

 either a condensing lens, a disc of blue 

 glass, or a pin-hole diaphragm. A milled 

 ring working in a screw-thread, tightens 

 or loosens the setting of the lamp, so as to 

 allow of its renewal in case of breakage. 



Queen's Acme Lamp.* — Mr. J. W. 

 Queen in designing this lamp (fig. 228), 

 has followed out his belief that a Micro- 

 scope lamp attaining the highest efficiency 

 could be produced at a low cost. 



The careful and exact application of a 

 finely figured, ground, and polished bull's- 

 eye lens permits the use of a very small 

 flame and wick. This feature will, it is 

 anticipated, prove a valuable one for sum- 

 mer work, where the heat of most lamps 

 is very objectionable. The bull's-eye 

 gives sufficient light for a 1/12 in. 

 objective, using only the usual substage 

 condenser w T hen the lamp is at the distance 

 of 3 feet from the mirror. 



The lens can be set higher or lower, 

 the flame placed flat or edgewise towards 

 the lens. The shade is japanned outside, 

 but bright inside, in order that it may become but little heated by 



* Micr. Bulletin (Queen's), iii. (18S6) p 27 (1 fiv.). 



Fig. 223. 



