AMERICAN INDUSTRIES SINCE COLUMBUS. 295 



power in 1790, by William Kelly, of Scotland. It was not until 

 1825 that the self-acting mule was evolved by Richard Roberts. 

 His second patent, dated in 1832, made the self-acting mule ap- 

 plicable to the wool manufacture. But its use continued to be 

 confined, for years afterward, almost wholly to the cotton manu- 

 facture. In almost all the American woolen-mills, down to the 

 close of the civil war, the spinning continued to be done on the 

 hand-jack, which is still found in many of them. The introduc- 

 tion of the automatic mule, which became general about 1870, has 

 enormously facilitated the manufacture. It is stated by careful 

 manufacturers that the substitution of the automatic mule, with 

 the other improved machinery which has come during the same 

 period, has resulted in a gain of fully thirty per cent, in production 

 in twenty years. The economical gain, in the saving of help, is 

 even more striking. Experts have calculated the difference be- 

 tween hand-jacks and mules in the cost of manufacture, as follows : 

 Forty-eight cents for one hundred run yarn, with the jack ; twenty 

 cents for the same yarn, with the mule, or less than one half. 



The hand-jack usually carries 240 spindles, revolving from 

 4,000 to 4,500 times a minute. Mules carry 300 or more spindles. 

 In the organization of a woolen-mill one set of cards, which re- 

 quires about twenty-six horse-power to run, will keep from 400 

 to 500 spindles in motion, although this relationship varies greatly, 

 according to the class of goods manufactured, the age of the 

 machinery, and the capacity of superintendents. American 

 woolen-mills run, in their equipment, all the way from one to 

 seventy sets of cards, and from 240 to 25,000 spindles. 



In the woolen manufacture proper, as now conducted, there is 

 but one process after that of carding and condensing to the per- 

 fect yarn, ready for the loom. The condensed sliver which has 

 come from the cards is in fact a sort of yarn, which requires only 

 twist and elongation to impart strength, firmness, solidity, and to 

 reduce it to the proper size. The mule has two distinct motions 

 which effect elongation and twist simultaneously. The carriage 

 travels backward and forward, and carries the spindles which 

 hold the bobbins on which the sliver has been wound, while in 

 the frame are fixed other bobbins, called condenser bobbins, to 

 receive the yarn. The machine in operation gives out from small 

 rollers, fixed in the frame, a certain amount of the sliver, simul- 

 taneously with the imparting of a degree of twist ; then the rollers 

 cease to revolve, while the carriage continues to recede, drawing 

 out the sliver to the necessary length, while in the mean time the 

 spindles, revolving with an increased velocity, furnish what is 

 called the finishing twist. The rollers limit the length of sliver 

 to be operated upon, the carriage draws it, and the spindles im- 

 part the twist. This is a very general description of one of the 



