142 MR. J. C. DYER ON THE ORIGIN OF 



the sheets of leather, (6) passing the staples through it, 

 and (7) pressing their crowns home to the sheet, (8) crook- 

 ing the teeth to the knee-bend, and then (9) advancing the 

 leather sheet to receive the next row of teeth, — these 

 complex and curious motions were produced by a series of 

 " cams,^^ or excentric pieces of steel fixed on a shaft and 

 turned by a winch. 



The invention, therefore, of " making wire-cards by ma- 

 chinery ^^ was thus accomplished by Amos Whittemore, 

 to whom the honour of this invention is solely due. 



In this machine, as in that of Mr. Heathcoat for lace- 

 making, a new principle of action had been applied by Mr. 

 "Whittemore to produce and govern the movements for 

 making wire-cards ; namely, the " wedge-pressure," con- 

 sisting of a series of " cams," or excentric curves revolving 

 on a driving-shaft, and giving the alternate movements to 

 the traversing parts of the machine in their exact order 

 for making and setting the card-teeth, as before explained. 

 Although in the old " iron-forging " and the " cloth-falling 

 mills " the trip-hammers and the cloth-beaters were worked 

 by radial levers or short arms from the driving-shafts, yet 

 they were used merely for elevating the hammers and 

 beaters, and not for guiding their motions, as the work 

 was done, in both cases, by impact, viz., by the falling of 

 the weights thus raised by the levers on the driving-shafts. 

 On the other hand, the cam motions in Mr. Whittemore^ s 

 machines were guided and determined in their due order 

 of succession to produce the nine distinct movements at 

 each revolution of the driving-shaft, as before described. 



It will be shown further on that this new and very im- 

 portant application of projecting curvilinear levers called 

 " cam pieces," fixed on driving-shafts, has since been ex- 

 tensively adopted for giving " intricate and regulated mo- 

 tions " in many other machines that have been invented 

 and patented within the last fifty years. 



