an Improved Grinding Machine, 341 



the principle now explained, a third speed could be fixed upon 

 the cone, then a fourth, and so on, till the required number of 

 speeds was put upon it. In a cone having a great many 

 speeds, the largest speed should be cast with arms and a centre^ 

 the same as for the small speed. A cone of this construction 

 could be ground upon a machine, as last described, by sepa- 

 rating it into speeds, and grinding the smallest one first ; then 

 the second smallest speed could be ground after it was bolted 

 upon the smallest speed, and so on, grinding one speed after 

 another, till the cone is finished. If cones were to be finished 

 upon a grinding machine, it would require to be made wider 

 than the one to be shewn in sketch No. 2.* — I am. Gentlemen, 

 yours respectfully, James Whitelaw, 



Late of 18 Russell Street, Glasgow, 

 now in London. 



• Report on Mr Whitelaw's Machine for grinding Cast-Iron Pulleys. 



Edinburgh, IQih July 1838. 



Your Committee, having attentively considered the drawing and descrip- 

 tion of this machine, are of opinion that it will produce the required effect. 

 They imagine, however, that there is a considerable defect in the arrange- 

 ment of the relative positions of the grindstone and of the dmm or pulley 

 to be ground. The communication is one of very high merit, and relates to 

 a subject every day becoming more important ; the Committee, therefore, 

 consider it worth while to criticise minutely the point referred to. 



In Mr Wliitelaw's arrangement the axes of the drum and of the grind- 

 stone are parallel to each other. Two inconveniences result from this : — 

 In the first place there is created a tendency in the drum to follow the mo- 

 tion of the grinder, which causes an undue, though not very considerable, 

 strain on the band or belt which leads the drum. In the next place, there 

 is a tendency to streak the surface. It is true that arrangements are made 

 to shift the drum length- ways upon the stone, so as to equalize the wear, 

 and to shift the positions of the streaks, but this, in the opinion of your 

 Committee, will merely palliate, not effectually correct the evil. If the 

 axes were placed at right angles to each other, both of these evils would 

 be removed ; and if, in addition, the motion of one or other shaft Avere re- 

 versed at intervals, a surface would be produced superior both in general 

 accuracy and in finish. The streaks then would cross each other obliquely 

 on the drum, and the ultimate result would be a very jlat surface ; of this, 

 one of your Committee has had abundant experience. 



Mr Whitelaw's proposed method of rounding pulleys would, no doubt, 

 answer perfectly ; indeed, there appears to be no distinction in principle, 

 and as little in practice, between the machine for giving a straight, and 



