704 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Plate XXIII. ( Figs, l and 2) serves to show thespecial appliances for 

 serial section cutting, parallel grinding, and work with the goniometer. 



Reverting to Plate XX., it will l>e seen that the base of the ma- 

 chine is a strongly built wooden bench or table, with dimensions as 

 follows : length'? feet, width 2 ft. 4 in., height 3 ft. 2 in. The table- 

 top, which is If in. thick, is supported on a strong, well-braced frame- 

 work, which is screwed to the wall of the building so as to ensure com- 

 plete freedom from vibration. The details of the construction of the 

 table may he readily made out from an inspection of Plates XX. and 

 X XII., except that a supporting beam for the three spindles, which runs 

 from end to end of the table, '.) in. below its surface, cannot of course 

 be seen. 



Details of the Principal Mechanical Parts. — These are described in 

 order, from right to left, as they appear in Plate XXI. First comes the 

 vertical revolving spindle of the slicer. This is made of mild steel — 

 as indeed are all the spindles — 15 in. long, by 1^ in. in diameter. It 

 passes through an accurately bored, flanged collar 8 in. long, screwed to 

 the surface of the table. The lower end of this spindle, as also those 

 of the grinding lap, is coned, and fits into a corresponding metal socket, 

 provided with an oil recess and protecting collar, which is screwed to the 

 longitudinal beam of the table-frame. The top of the spindle is threaded, 

 and carries carefully fitted collars and flanges for clamping the slitting 

 discs. 



Somewhat to the right of and behind the spindle of the slicer, is a 

 rod of steel, 1 in. in diameter and 18 in. iong. The lower part of this 

 rod, which is of somewhat greater diameter than the upper part, is 

 coarsely threaded for 6 in. of its length, and screws into a long nut or 

 socket fitted to the table, thus forming an adjustable support for the 

 various specimen clamps. The rod has 3 in. or more of motion by 

 means of a screw, and a further range is obtained with the aid of lock- 

 nuts sliding on the spindle itself. 



The larger specimen-holder is of the usual parallel screw-clamp 

 type, and will hold specimens up to 5 in. in diameter. Several inter- 

 changeable clamps are used ; one of these, to be seen in the photograph 

 (Plate XXL), is adapted to hold thick pieces of plate glass 3| by 1|- inches 

 (length and breadth), to which the ordinary microslips are attached. In 

 addition to its radial motion, this carrier revolves axially, so that speci- 

 mens to be sliced may be tilted at any convenient angle in relation to 

 the slitting disc. This clamp also carries the goniometric crystal-holder 

 (shown in the front right corner of the tray), which permits of slicing 

 or grinding in any desired direction. The device for maintaining a 

 steady pressure or pull against the slicer comprises the usual cord, weights, 

 and pulleys, so placed as to be readily controlled. 



Lubrication of the slicer is provided for by means of a drip-can and 

 two pieces of sponge, one above and one below the disc, held in position 

 by a spring clamp. 



Passing now to the grinding laps, of which there are two, seen in 

 the centre of the table, it will be noted that they are screwed to the top 

 of the spindles by means of a threaded boss below each plate. This 

 mode of mounting allows the whole surface of the lap to be utilized,' and 



