OF SAMUEL CROMPTON. 337 



great importance to the machine. But the cir- 

 cumstance of the interval being very short, in 

 making the machine tolerably correct, shews that 

 many heads must have been at work. What led 

 to the enlargement and the forming of the parts 

 of the mule, with additional strength and accu- 

 racy, was the application of artificial power, 

 which was first introduced by Mr. Kelly, of 

 Glasgow,* 1790, formerly of the Lanark Mills. 

 The way in which Kelly applied this artificial 

 power to the usual hand-mule, was simply by 

 a loose pulley, to which a catch was attached, 

 which could be made at pleasure to seize another 

 catch fixed to the axis ; on this axis was placed 

 a screw, which worked into a wheel, the number 

 of whose teeth governed the number of revo- 

 lutions of the rim, by disengaging the rope from 

 the fast to the loose pulley .tk Immediately after 

 the introduction of this power, Mr. Wright an 

 ingenious machine maker of Manchester, an 

 apprentice and workman of Sir R. Arkwright's, 

 constructed the double mule, embracing the 

 advantages of Kelly's application of artificial 

 power. The double mule was constructed by 

 placing the rim in the middle of the frame or 

 rollers. I believe he had four hundred spindles 



* Two years after this, he took a patent for a self^urtioff 

 mule.— See his letter to me, 8th of January, 1829. 



2 u 



