336 Mr Whitelaw's Description of 



so as to do certain kinds of work in an expeditious and accurate 

 manner, and from some experience which I have had in work- 

 ing it, I am of opinion that it might be applied to a greater 

 variety of work, and much more extensively than it has ever 

 yet been. I \wi\\ first give you an account of a machine planned 

 by me for grinding pulleys or drums trnhj (ylindrical on the 

 rim, which has been much in use during thelast eighteen months. 

 After I have described this first machine, I will give you an 

 idea of another machine, which has never yet been brought 

 into practice, for grinding pulleys, &c. rotmd on the rim; and 

 then you will, I believe, be of opinion that grinding machines 

 might be used to great advantage in factories where mill- 

 ffearino; is made. 



Plate I. Fig. 1, of sketch No. 1, is a side elevation of a 

 machine for grinding drums or pulleys of a truly cylindrical 

 shape, or, as it is called, straight on the rim, and Fig. 2, is a 

 ground-plan of the same machine. The parts which are seen in 

 both Figs, are marked by the same letters in the one Fig. as in 

 the other ; aa is the grindstone, and bb is the pulley which is to 

 be ground. The pulley bb is fastened upon the mandril c c, this 

 mandril is fixed into the spindle dd at the one end, and it works 

 into a plummet-block e at the other end. The speed of the grind- 

 stone is 180 revolutions per minute, and the pulley bb makes 130 

 revolutions in the same time ; the stone and the pulley revolve 

 in the same direction, in order that the parts in contact may rub 

 upon each other at the combined speed of their circumferences. 

 There is a small shaft jOf/ w hich, by means of the mitre wheels 

 fixed upon it, gives motion to the screws gg^ gg^ gg^ in con- 

 nection with the plummet blocks, into which the spindle dd 

 and the mandril c c work. As the plummet-blocks slide upon 

 the rails h, h, Ii^ which form part of the framing of the ma- 

 chine, in a similar manner as the parts of a slide-rest move, 

 and as all the screws marked gg have the same pitch of thread, 

 the spindle and the mandril are shifted at once, either from, or 

 towards the grindstone, and keep always parallel to its shaft, 

 if the handle or wheel v is moved by hand. Upon the end of 

 the shaft of the grindstone, a bevel pinion i is fixed, and this 

 pinion gears into the wheel Z; A*, fixed upon the shaft /. The 

 shaft I is bored out to fit the shaft vi m, which is turned parallel 



