650 Caldwell's automatic miceotome. 



parallelism of the sides of the mass to be cut are the most 

 important points in the whole process.^ Underneath the frame 

 containing the object is a large brass milled head (fig. 2, c). 

 By turning this the object may be raised or lowered according 

 to the direction in which it is turned. This should be done 

 until the object is just below the edge of the razor. The plate 

 holding the razor should then be moved so that the edge of 

 the razor is close to and quite parallel with the mass of material 

 to be cut*^ (fig. 3). The plate should then be clamped by the 

 screws at each side of it. A few turns of the flywheel will 

 now bring the razor in contact with the object to be cut. The 

 band of black ribbon (figs. 1 and 3, d) is now to be placed so 

 that the end of it should be just above the razor and clamped 

 in that position. When the handle is turned the sections 

 should come off the razor in the form of a ribbon. 



The ribbon of sections will not find its way to the continuous 

 black band without assistance. With a needle in a handle 

 or with the point of a scalpel pick up the end of the ribbon^ 

 when a sufficient length of it has been cut, and place it on the 

 black continuous band, up which it will travel. When it 

 reaches the top of the band suitable lengths may be cut off 

 with a pair of scissors. It may be found that the black band 

 travels either too slowly or too fast. Its speed may be varied 

 by moving the ring (fig. 1, e) up or down upon the vertical 



^ The Cambridge Scientific Instrumeut Company, Cambridge, the makers 

 of the instrument, have nearly completed an automatic machine for sharpening 

 razors, since it has occurred to them that this is an operation which may be 

 performed with much greater acruracy by mechanical means than by hand. 



^ The distance through which the sliding stage moves can be altered by 

 raising or lowering the arm (figs. 1 and 4, j). This distance should be so 

 arranged that the surface of the embedding mass containing the object to be 

 cut just clears the razor when the sliding carriage is at its maximum and 

 minimum distance from either end of the machine. This is important as the 

 speed with which the black band travels varies directly with the throw of the 

 machine. If this adjustment is made and a little care is used in adjusting the 

 ring (fig. 1, e), see below, the ribbon will move at each turn of the flywheel 

 through a distance equal to the breadth of the surface which is being cut. If 

 on the other hand the object swings far beyond the razor the band will travel 

 too quickly and probably break the string of sections. 



