268 Mr Sang's Annual Report on the 



one may occasion motion in the others. By this means the ap- 

 plication of the hand is entirely avoided, and even the effects of 

 unequal rapidity in the motion of the tool destroyed. To com- 

 plete the change, the bed of the lathe is converted into the lower 

 slide of the slide-rest. 



The most beautiful specimen of the self-acting lathe which I 

 have met with, is in the works of Mr Whitworth, works which 

 are indeed crowded with well-made and excellently designed 

 instruments. 



This lathe, somewhere about twenty feet in length, is fully 

 finished in all its parts, and kept in a style which shews that the 

 workman is conscious of the merits of his tool. Along the bed 

 of it there runs a screw, accurately divided, the work of some 

 two or three months; this screw is seldom stopped. It works 

 in a split box, which can be opened and shut at will, thus al- 

 lowing of the instantaneous disengagement of the plate which 

 carries the cutting tools. This plate carries a small wheel 

 which the screw works, so that the axis of this wheel is constantly 

 turning round. By applying the hand to the winch attached to 

 this axis, the screw, whether revolving or stationary, is converted 

 into a rack, and the slide is brought at once opposite any part 

 of the work. The split-box is then engaged, and the cutter 

 moving slowly along the bed, cuts either the thread of a screw, 

 or the surface of a cylinder, according to its form and relative 

 rapidity of motion. 



If, however, it be wished to turn a flat surface, the cutter 

 must be moved at right angles to the bed of the lathe. For this 

 purpose, the split-box being disengaged, the small wheel already 

 mentioned is connected with the axis of the transverse screw of 

 the slide-rest, and by a simple arrangement may be made to 

 move the tool either outwards or inwards. Thus the workman, 

 bv merely arranging the engaging and disengaging apparatus, 

 giving his commands as it were to the machine, produces what 

 kind of work may be required. 



In this particular lathe, the leading screws and other gearing 

 are carefully concealed beneath the plates, so as to remain un- 

 injured by the fragments which fall from the work; at the same 

 time, those parts by which the gear is changed, are brought out 



