ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



793 



The principle of the instrument is the same as was described in this 

 Journal, 1887, p. 796, where a Microscope with four tubes was figured. 

 A totally reflecting prism is placed over the objective, and as this is 

 rotated by the milled-head at the top, the image is thrown into each 

 of the tubes in succession, thus enabling a Professor to show the same 

 object to various members of his class. 



Four of the tubes have each two screws for centering in two rect- 

 angular directions. They also have each a rack and pinion for focusing. 

 An unavoidable difficulty of the instrument is, that the object appears 

 differently placed to the different observers, but a mark in the field of 

 each of the four tubes shows which was the right-hand side of the object 

 to the observer using the first tube. 



Schieck's Meat-examining IMicroseope. — Herr F. W. Schieck has 

 applied to this Microscope (fig. 121), an arrangement for inclination, 



Fig. 121. 



which, although adopted in the case of small instruments, has not been 

 hitherto applied, so far as we know, to those of the sixe of his 



