ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 887 



forwards up the inclined plane. Each carrier runs on three ivory 

 knobs. The knife-carrier is kept straight on the slide-way by means 

 of two lateral flanges which work against the vertical plate. The 

 object-carrier is fitted with two knobs which bear against this surface. 

 The motion is very smooth and safe. Both carriers can bo removed 

 and replaced without losing their position. The knife-carrier consists 

 of a flat support for the knife and of a clamp ; it revolves round a 

 central screw, and is provided with a groove below for the reception 

 of the cylindrical knife-handle. In this way the knife can bo 

 adjusted both for its surface and longitudinal axis. The object- 

 carrier consists of a simple block of wood provided with the above- 

 mentioned projections, three below and two at the side. In the middle 

 it has a 25 mm. opening for a binding-screw. 



It is often desirable to place an object in a particular position, 

 and this is provided for by a very simple screw clamp with universal 

 movement. This is represented in the foreground of fig. 183. 

 Although this apparatus is made in one piece (except the vice), it 

 can be more easily described as if it consisted of several parts. A 

 screw bolt with a head 25 mm. square is fitted with a metal loop, 

 the ends of which are fastened to two sides of the square bolt for the 

 reception of a movable block or vice, flat on the side turned towards 

 the bolthead, and fluted towards the concavity of the loop. This 

 clamp or vice is twice as long as it is broad. The arrangement of 

 the object-carrier is as follows : — Upon the broad base (9x9 cm.) 

 of this carrier, a block of such thickness is fastened vertically, 

 that about three-fifths of the space towards the vertical surface remains 

 free. This upright block is perforated for the reception of the 

 above-mentioned bolt with its loop. Two-thirds of this perforation 

 is of the same width as the diagonal measurement of the bolthead, so 

 that this therefore can revolve within the round opening. The next, 

 however, is wide enough to let the bolt itself pass -through. If the 

 cylindrical object-holder be placed between the vice and the loop, 

 and the screw of the bolt turned, it will be firmly held, because the 

 screw draws the loop but not the vice towards it. As the axes of 

 the object-holder and of the screw clamp stand vertically towards 

 each other, the object may be inclined in any direction. When 

 used, the object-carrier is held with the thumb and index finger of 

 the left hand, and pressure made backwards towards the micrometer- 

 screw, and onwards towards the vertical plate. 



The author states, that with three microtomes which he has had 

 made to this pattern, he has found that one complete turn of the 

 micrometer-screw raises the object 1/500 in. (0'0508 mm.). 



Vinassa's Microtome for Pharmacologists.* — The body of this 

 instrument (figs. 184 and 185), invented by Dr. E. Vinassa, is formed 

 by a heavy frame (H cm. square) A B C D, 45 cm. long and 18 cm. 

 broad. The two longitudinal bars are joined in the middle and at 

 the ends by three cross-bars A B, E P, D C, while at the corners and 

 in the middle of the long sides are six supports, 12 cm. high, G D, II E, 



* Zeitschr. f. Wis*. Mikr, ii. (1885) pp. 309-20 (4 figs.). 



