June 4, 1897.] 



SCIENCE. 



863 



of cast iron. The kuife is held by two 

 clamps, which cau be fastened at anj' point 

 in the slots upon the upper part of the 

 square frame, so that the knife may be 

 either at right angles or at auj^ desired in- 

 clination to the direction of the draw in 

 cutting. As the knife blade is thick and 

 strong, and is clamped at both ends, the 

 cutting edge is rendered almost immovable. 

 Underneath the knife-bearing frame are the 

 two horizontal ways, upon which runs the 

 sliding carriage. It will be noticed that 

 the general construction of the whole ma- 

 chine resembles in principle a lathe-bank. 

 The carriage itself is a broad platform with 

 a raised rim ; by its size the danger of tilt- 

 ing in anv direction is rendered small: 



between the two horizontal waj's. At the 

 bottom of the screw there is a large toothed- 

 wheel, which is utilized to feed the screw 

 automatically. The toothed-wheel is turned 

 either to the right or left, as desired, by 

 means of the lever, the long handle of which 

 is seen projecting at the bottom of the 

 figure. The figure also shows the lever 

 resting against a vertical bar. When the 

 carriage is moved the micrometer attach- 

 ment and the lever are moved along with 

 it, and when the lever strikes against the 

 vertical bar it is forced to turn the toothed- 

 wheel and so work the feed of the apparatus. 

 It will be noticed that the vertical bar is 

 borne upon an arm, which can be slid to 

 and fro upon the body of the microtome 



the raised i-im serves to retain the alcohol, 

 which drips from the specimen above and 

 prevents its falling upon any of the working 

 gear ; from the surface of the carriage the 

 alcohol is drained off by a tube, which, 

 being upon the further side of the instru- 

 ment, is not shown in the engraving. The 

 object-holder is a square box, and is so de- 

 vised that it can be readily lowered or 

 raised, and renders it easy to adjust the 

 plane of the section after the object has 

 been clamped iu. As the object-holder is 

 supported firmly immediately under its own 

 center, the possible leverage is minimized. 

 The object is raised b}' a micrometer screw, 

 which works with a vertical tube which 

 descends from the middle of the carriage 



and clamped at any point as wished. By 

 these means the lever can be set in action 

 at any desired point of the excursion of the 

 movable carriage. 



The arrangement for the automatic feed 

 is similar to that employed in de Groote's 

 microtome. As modified for the needs of 

 the ' Precision Microtome,' the device seems 

 to me to leave little to be desired on the 

 score of either convenience or accuracy. 

 Figure 4 gives the plan of the arrangement. 

 The following description of the feed was 

 drawn up by Mr. Bausch : 



" The feed arrangement consists of a 

 micrometer screw, having pitch of 0.5 mm., 

 which elevates the object-holder. 



" The motion of the screw is transmitted 



