206 



THE AMERICAN MONTHLY 



[November, 



bears against a projecting flange on 

 the upper end of the v-shaped bed. 

 so that no matter how hard the ma- 

 terial may be, the knife moves stead- 

 ily through it without deviating from 

 its plane and without requiring any 

 extra pressure. The upper surface 

 is provided on its entire length Avith 



straight or very oblique cut. the car- 

 riage with object may be placed at 

 such a point where it is the most 

 convenient in its relation to the cut- 

 ting edge. 



' To the carriage are directlv fitted 

 the micrometer screw with graduated 

 disk and a slide whicli is acted upon 



KiG. aO. — BrfUscli & Lomb Microtome. 



a grooved slot, to which is fitted a 

 sliding thumb-screw, so that the knife 

 may be fastened at any point upon it. 



• The knives, ■which are specially 

 made for these instl-uments, have a 

 curved arm with slot, so that any 

 part of the cutting edge may be used ; 

 they are made of the finest steel and 

 are guaranteed. Stop-screws witli 

 soft rubber cushions are fastened at 

 the ends of the angular way. 



' The front vertical bed is planed 

 and polished and is arranged with a 

 grooved slot its full length. The ad- 

 justable carriage is fitted to it and 

 may be securely fastened at any point 

 upon it by means of two heavy 

 screws. The tightening pin for these, 

 when not in use, has a receptacle in 

 the solid bed. It will thus be seen 

 that, whether it is desired to make a 



bv the former. A provision is made 

 for taking up the possible wear on 

 the screw. At one side of the car- 

 riage a spring is attached which 

 works in the grooves on the edge of 

 the disk witli a pronounced click, so 

 that the feed may be controlled with- 

 out watching it ; this may be loosened, 

 so that it will not act, when it is de- 

 sired to use the index only. A lever 

 with ivory handle is connected with 

 the slide, so that this may be re- 

 turned after the screw has come to 

 the limit of its motion. 



' The slide is provided with a 

 grooved slot, which admits of the 

 quick adjustment of the universal 

 joint and clamp for specimens of dif- 

 ferent lengths. The universal joint 

 permits inclination in any directioti 

 and the clamp will receive objects up 



