300 MR. J. C. DYER ON 



the rovings are slightly twisted, they have no strength for 

 guiding the taking-up motions of the bobbins ; wherefore 

 they must be driven apart from the flyers, with a variable 

 speed, as aforesaid. 



Had no more been required than to secure a regular 

 diminishing speed of the bobbins directly as their di- 

 ameters were enlarged by the rovings wound upon them, 

 the relative motions of the flyers and bobbins could be 

 easily obtained by the common traversing straps working 

 over reversed cone-pulleys. But frequent readjustments of 

 those motions were required in using the different sorts of 

 cotton (as coarse and fine, long and short staple, and the 

 like), in which more or less twist was necessary to fit the 

 roving for spinning ; and in the changes of twist the speed 

 of the delivering rollers had also to be changed, and con- 

 sequently that of the bobbins for taking up such varying 

 lengths of rovings in equal times. We must keep in view 

 that if the rovings have too little twist, they will stretch 

 and become uneven, through lack of strength to turn the 

 bobbins in drawing them off for spinning. Now these fre- 

 quent readjustments of the differential motions above men- 

 tioned constitute the main difficulties in using the bobbins 

 and fly frames. In carefully considering the nature of 

 the operations performed by this machine, no surprise will 

 be felt that so many years should have passed in trials to 

 improve its working before the discovery of any effectual 

 plan for securing the differential motion by a self- regu- 

 lating apparatus. 



From 1 8 15 to 1825 I ^^^ witnessed the progress of the 

 many improvements in the construction and the method of 

 regulating the delicate movements of this roving-frame, — 

 those of the greatest value in practice having been made 

 or suggested by my late friend Mr. John Kennedy, of 

 Ardwick Hall, whose well-earned fame as one of the most 

 ingenious and talented mechanicians of his time is too 



