ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



825 



The vertical axis of the toothed wheel z on the top of which the 

 object-carrier rests, ends below in a screw with a pitch of 0"75 mm. 

 The knife-carrier at each cut pushes against tho lever h, the hori- 

 zontal arm of which catches in the wheel z, which has 100 teeth. At 

 the commencement of each cut a spring s draws the lever back ready 

 for the cut. The lever is regulated by h c, so that it will move the 

 wheel z only one tooth forward or several teeth up to ten. The 

 wheel is prevented from moving backwards by a catch attached 

 too. Sections of 0- 0075-0 '075 mm. can thus be cut. If sections 

 thicker than 0'075 mm. are required the automatic apparatus is 

 detached, the catch at a being removed and the spring s detached. 

 The thickness of the section is now indicated by the pointer g and 

 the graduations on the periphery of the wheel. So that the knife 

 may not inadvertently cut against the object-carrier a contrivance is 

 added which prevents the lever working in the wheel after a given 

 height has been reached. The axis /of the object-clamp is fixed by 

 the screw e, so that it can be raised or lowered. The jaws can be 

 brought closer together by d. The tray W serves for catching 

 spirit, &c.* 



The instrument fig. 141 is a larger form of the previous instrument, 

 38 cm. long instead of 20 cm. 



Decker's Section-smoother.j — Dr. F. Decker describes the appa- 

 ratus shown in fig. 142. The essential principle consists in the 

 application to the knife-blade of a glass cylinder a, which can rotate 

 on an axis h c. 



Fig. J 42. 



The knife has attached to it a steel bow e e. By turning the 

 screw /, which acts on a long steel plate g, the bow is made to grip 

 the knife tighter. The block h is attaclied by a hinge to e (its axis 



• Cf. Zeitsclir. f. Wiss. Mikr., i. (1884) pp. 241-4 (1 fig.), 

 t Arcli. f. Mikr. Ai.at., xxiii. (1884) pp. 537-43. 

 Ser. 2.-VOI,. IV. 3 I 



