612 



Journal of Applied Microscopy. 



at which the cutting is to be done. The knife-carrier (A) moves on the upright 

 steel rods (a, a,)kept rigid by the braces (b, b, b, b,) each of which may be reg- 

 ulated with a bolt. Even motion is further assured by two rollers (c, c,) pressed 

 against the steel bars by a strong spring to which they are attached, and also by 

 passing the handle of the knife-carrier through the cross bar at (f) giving a 

 third support at a higher level than (h, h,) where the upright bars pass through 

 the carrier. 



The knife (Fig. 1 B and Fig. 2) is a thick steel blade with two beveled edges 



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FIG. 2. 



FIG. 3. 



(i, i,) and two handles (i', i',) which fit in the oblique grooves (k, k,). The knife 

 is kept firm at the required angle by four paired screws (1, 1, 1, 1,). The horizon- 

 tal carrier (C) has two lateral grooves by which it rests on the horizontal 

 slide (m, m,) which has a scale (n), for determining the exact size of the paraffin 

 blocks. The adjustment screw (D) moved by the lever (o) turns the carrier with 

 the paraffin block in the horizontal plane. This screw has a pitch of about 

 y2 mm. and the end of it is hollowed out to fit the point of the set screw (p) 

 which holds it in place. 



At the base of the support (E) for the paraffin holders which go with the 

 microtome, there is a graduated disc (F) with regular notches to receive the 

 spring click (q). By means of these the paraffin block can be accurately oriented 

 and cut in any form desired. 



To manipulate the instrument, the knife is fixed at the desired angle, the 

 knife-carrier raised, the paraffin block oriented and bits of it chipped off, the 

 carrier being turned by the lever (o) after each stroke until a first surface is 

 defined, then the graduated disc is turned at the desired angle and the other sur- 

 faces are cut. 



With the apparatus, blocks may be cut varying in size from less than 1 mm. 

 to those 7 cm. high and with a base 8 cm. square. If desired, a notched knife 

 for tracing lines may be used instead of the razor. The parts of the instrument 

 are made of bronze, brass, nickel and steel. The different pieces may be detached 

 and readjusted by screws. When the knife carrier is raised, the microtome is 

 about 85 cm. high, the horizontal slide gives the carrier a play of 8.5 cm. and 



the knife may be moved through 7 

 cm. The instrument rests on three 

 legs screwed to a firm brass plate 20 

 cm. long, and 18 cm. wide. 



The model for mounting sections 



(Fig. 4) is a block of wood having 



PIQ_ 4_ a depression the size of the slide. 



