640 



SUMMAKY OF QUERENT RESEARCHES RELATING TO 



of microtome (figs. 178 and 179) brought cut since 1888, and of interest as 

 being tbe first to exhibit a completely circular knife-movement. The 

 frame is a cast-iron tripod on a triangular base, tbe three pillars being 

 connected with one another. One of these pillars is provided at its upper 

 end with a socket in which a ball of corresponding shape fits, forming 

 the extremity of a travelling arm. The two front pillars are connected 

 at their upper ends by a strong cast-iron arc-piece, on whose upper plane 

 face the distal broadened end of the traveller finds support and guid- 

 Two small round-headed steel knobs, screwed into the under side 



ance. 



Fig. 179. 



of the broadened end of the traveller, give it a steady support and easy 

 movement on the circular frame. Thus the traveller moves circularly 

 round the ball-and-socket joint as its centre. Tbe traveller is mortised 

 about 20 cm. from the free end for the purpose of taking the knife- 

 holder, which is adjustable at any point of the mortise, and is clamped 

 by a butterfly nut. The knife is fastened at each end by screws to the 

 lower faces of a pair of lateral flanges, whose heads are perforated and 

 connected by a horizontal arm forming part of the knife-holder. An 

 indicator at one extremity of this arm regulates the setting of the knife, 



