ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



861 



Fig. 186. 



mann's friction-stage works, and a rotating disk of diaphragms is 

 fitted within the thickness of the stage. A substage-tube is applied 

 beneath by means of a horizontal bayonet-joint. 



ScMeck's Microscope with Screw Stage -Micrometer. —The 



micrometer attached to this instrument (fig. 186) differs somewhat 

 from English models in having a 

 rotating plate* for the object, and a 

 second movement from back to front, 

 actuated by a screw at right angles to 

 the motion of the micrometer-screw. 

 The position of the object to be 

 measured can thus be readily centered 

 when the Microscope has no mecha- 

 nical movements to the stage. The 

 micrometer-screw registers 1/5 mm. 

 to each revolution of the drum-head, 

 the whole turns being read on an 

 engraved scale on the edge of the 

 moving plate, whilst the drum-head is 

 graduated in 100 divisions, and by 

 means of a fixed vernier tenths of these 

 divisions can be read. (In the fig. 

 one of the clips is shown turned back 

 away from the stage.) 



Microtome-Microscope, t — " Mr. 

 " C. P. Hart described [to the Section 

 " of Histology and Microscopy of the 

 " American Association for the Ad- 

 " vancement of Science] a clever 

 " manner of making a Microscope into 

 " a microtome, by using the tube to 

 " carry the imbedded object, and the 

 " movable stage to carry the razor ; the object to be cut is moved by 

 " the fine adjustment." 



Duboscq's Projection Microscope.| — MM. T. and A. Duboscq 

 describe their apparatus as follows : — 



" This apparatus consists of a system of lenses, or condenser, to 

 converge the illuminating rays and cause them to pass through an 

 achromatic objective serving to project the images on a screen. 



The novelty of our apparatus consists in the addition which wo 

 have made to the condenser for the projection of microscopic objects. 

 There is a stage furnished with a lens which shortens the focus of the 

 condenser and concentrates the greatest amount of light on the object. 



• ZeisB'fl stage-micrometer (see this Journal, iii. (1883) p. 573) has a rotating 

 plate, and wc have seen a similar arrangement to the above on a Microscope con- 

 Btructed forty years ago by Plossl ; wo are informed, however, that the plan was 

 originally devised by Hchicck. 



t Bcionce, vi. (1885) p. 228. 



i OjmptoB RenduH, ci. (1885) pp. 47G-7. 



