58 The Microscope. 



perfectly smooth, clamped together and two f-inch holes bored 

 midwa}' between the sides, 1^ inches respectively from one of 

 the ends. Two other pieces, |xl|xl2 inches, are also made 

 perfectly smooth. A strip of felt or cloth, 3 inches wide and 12 

 inches long, is glued to a face of each of these four strips of 

 wood, passing the cloth around and fastening to the edges in 

 the case, of the two narrow strips. This done, the four pieces 

 are screwed together lengthwise in such a way that they will 

 form a square well, and be flush at the end opposite to that hav- 

 ing the holes in the longer pieces. In this way we have formed 

 a felt-lined, square well, about 1^ inches on a side and 12 inches 

 deep. A square piece of wood, about 1^ inches on a side and 

 11 inches long, is made perfectly smooth and fitted into this 

 well, so that it may move vertically with slight friction against 

 the felt-lined walls. Into the end of this square piece a hole, 

 about I inch in diameter and 1^ inches deep, is bored in the 

 direction of the axis, into which the roll of paraflSn containing 

 the object to be sectioned, may be firmly wedged by means of 

 crescent-shaped wedges. Two glass slips, such as are used for 

 mounts, are now glued parallel to each other across the ends of 

 the 3-inch pieces in such a way as to allow the paraffin roll to 

 rise between them. 



Now, turning to the other end, two round pins are fitted to 

 pass through the holes bored in the 3-inch strips, and about 

 these is rolled a long ribbon of stout manilla paper. If inches 

 wide and from 10 to 12 feet long. Most of the paper is first 

 rolled on the lower pin, and then the free end is fastened to the 

 upper pin and several turns made. The central shaft of wood 

 bearing the paraffin roll in its upper end, is now pushed down 

 in the well until its lower end bears upon the upper roll of 

 paper. The paraffin roll is adjusted and trimmed so that its 

 upper end is on a level with the surface of the glass slips. As 

 the paper is now unrolled from the lower pin and rolled upon 

 the upper, the latter roll, by its increasing diameter, pushes the 

 central shaft upward, and sections of any desired thickness, or 

 thinness, may be made by passing a stout razor over the glass 

 slips. One complete turn of the upper pin, of course, raises the 

 shaft just the thickness of the paper, and any fraction of a turn 

 raises it just that fraction of the thickness of the paper. The 

 microtome should be clamped to the work-table. 



