84 



SUMMARY OF CUREENT RESEARCHES RELATING TO 



from figs. 13 and 14, the object-portion consists essentially of a heavy 

 metal block, of rectangular shape, which slides in a groove made in the 

 upper surface of the heavy base-plate. The longer lower edges of this 

 block are to a certain extent rounded off so as to minimize friction, 

 and the movement is kept true by the presence of the vertical lateral 

 faces of the block against the vertical faces of the groove. A slight 

 allowance is made in dimensions, so that the block runs smoothly in its 

 groove and jamming is impossible. As the block has been intentionally 

 made very heavy, it cannot jump when the object meets the knife. 

 Moreover, the object-holder is placed in the axial line of the block, and 

 this arrangement secures that the resistances of object and knife are 





■ •? 



Fig. 13. 



collinear with the axis of movement. The effect is, therefore, still 

 further to reduce any risk of oblique disturbance of motion. 



The object-block is operated by a knob rotatory on a vertical axis 

 and geared to a disk, which again is geared to the object-holder. The 

 disk is divided into 20 divisions, each of which corresponds to an eleva- 

 tion of 1 p. of the object-holder. The pointer of the disk is therefore 

 set to correspond with the required thickness of section. A right turn 

 of the operator's hand on the knob, puts the gearing into action, and 

 therefore causes the elevation of the object ; a left turn then brings the 

 knob back to zero. The order of operations would be : rotate knob to 

 right, push forward, cut, draw back, rotate knob to left. Or the order 

 might be : rotate knob to right, push forward, cut, rotate knob to left, 

 draw I tack. It is found that after a little practice one hand can perform 



