308 MR. J. C. DYER ON 



tain the relative speeds of the prime motions in the fly 

 frame. This is effected by the action of three wheels or 

 pulleys* revolving together^ and geared so that one of 

 them was driven faster and the other slower by the middle 

 wheel^ as the rotations of the latter were governed by those 

 of the delivering-rollers. This apparatus at the time was 

 known by the significant title of " Houldsworth's Jack-in- 

 the-Box ; '' and in fact it did solve the " differential pro- 

 blem " which had so long baffled so many clear heads to 

 master. I must be content with thus pointing out the 

 general properties of the different classes of the roving- 

 frames above noticed, as it would be vain to attempt a 

 description of their minuter parts without drawings to 

 illustrate them. 



The successful application of the presser and the Jack- 

 in-the-Box again turned the scale in favour of the bobbin 

 and fly frame as competing with the tube frame ; and the 

 former may be held as the most complete triumph of 

 genius and scientific skill now exhibited in the cotton- 

 mills, with the sole exception of the self-acting mule, as 



* This important invention of Mr. Hoiildsworth was at first carried into 

 effect by pulleys and straps ; but, from their liability to slippage, it was found 

 desirable to substitute toothed wheels in place of pulleys. The suggestive 

 nature of new discoveries was then strikingly shown; for this want soon 

 drew the attention of other eminent mechanicians to the subject, among 

 whom both Mr. John Kennedy and Mr. Peter Ewart succeeded in giving 

 the same motions by means of three wheels so acting together that the 

 middle wheel controlled the relative speeds of the outer ones, just as Mr. 

 Houldsworth had done by tlie pulleys. Mr. Ewart employed mitre wheels, 

 and Mr. Kennedy adopted spur-gearing ; and the latter, I believe, has been 

 found the most simple and best in practice. It is also worthy of remark 

 that, shortly after the application of the three mitre wheels to govern the 

 varying motions in the roving-frame, it was found that the same action of 

 three mitre wheels had for many years been in open use for giving a uni- 

 form surface speed in the side lathe for turning conical pulleys, just such as 

 are used in the roving-frames : so here was a curious discovery by Mr. 

 Ewart of a new use for an old action of wheels, which he had often seen in 

 operation with the turning-lathe, but dreamed not of its being of value for 

 other purposes, until led thereto by the new want, as above. 



