ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 781 



F. The handle, which is so fitted on the axis P P that it carries the 

 cutter and the piece e e round with it. 



G. A nut that screws the handle on its axis and keeps the cutter 

 flat to the bell-metal B B when carried round by the handle. 



o o o is a hole, nearly in shape of the sector of circle, pierced through 

 that part of the bell-metal which the edge of the cutter traverses, and 

 continued through the whole length of the cylinder, truly parallel to its 

 axis and of an exact equal width throughout, till it terminates in the 

 plate C. 



H represents the end of a piece of wood of which slices are to be cut, 

 and which is put into the cavity ooo, into the angular part of which it 

 is gently pressed by means of K K, two brass screws, which pass through 

 the ivory into the cavity ooo, and are made to press on the wood h by 

 means of L, a key that fits into hollow squares made in the screws K K. 



M. A screw that passes through the brass plate C, opposite the 

 middle of the cavity ooo, and by means of which the wood h is raised 

 to the cutter. This screw has forty threads to an inch, and its head, 

 being divided into twenty-five equal spaces, it is evident that the 

 moving one of these divisions or spaces will make the screw advance, 

 and raise the wood h just T qVo °f an inch. 



N. An index that points the divisions on the head of the screw 

 M. The breadth of this index, from the one fiducial edge to the 

 other, subtends a division and a half on the head of the screw, by 

 which means half divisions as well as whole ones may be accurately 

 shifted, and the 5F jio> tsWj toW yio> etc -> P art,s of an inch, truly 

 estimated. To render the effect of this screw the more certain, its point 

 is turned round so as to act very near the centre, and a piece of ivory 

 (see 3) is carefully fitted into the cavity ooo so as to move freely 

 therein without any lateral shake, and to rest on the end of the screw M. 

 This piece of ivory acting equally on every part of the under surface of 

 the wood, will raise it towards the cutter with much more certainty than 

 if the screw acted immediately on it. Several such pieces of ivory, of 

 different lengths (as represented by 3), ought to be fitted to the 

 instrument, so as readily to suit the length of any given piece of wood. 

 One piece, of the full length of 3, must have one end left rough 

 from the file, that pieces of cork, agaric, the pith of wood, and such 

 other soft substances, may be cemented on it with sealing wax, in which 

 case they can be cut into slices of a determinate thickness, as well as 

 wood. 



Now if a piece of wood, whether round or of the shape represented 

 in the instrument at h, and of whatever size, be put into the cavity 

 ooo, and gently pressed into the angular part thereof by the screws 

 K K, let it be raised towards the cutter by means of the screw M. If 

 the handle be turned to the right, the edge of the cutter will advance 

 on the wood, and cut off such part as lies above the plane in which the 

 edge of the cutter moves, and when the upper surface of the wood is 

 thus rendered flat, slices may be cut of any required thickness, according 

 to the number of divisions that the screw M is made to advance. If 

 the machine be made with due care, it will readily cut a thousand slices 

 in an inch, and if the edge be good and very well set, slices may be cut 



