James Hargreaves invented the spinning Jenny circa 1764.

The source of the name "Jenny" seems to be in doubt. One suggestion was that it was named after his wife (but her name was Elisabeth?). The story that it is named after his daughter who knocked it down may be a myth. Does "Jenny" as another word for an engine predate the Hargreaves usage?

From Espinasse, Francis. Lancashire Worthies. As reproduced in Readings in Modern European History, ed. James Harvey Robinson and Charles Beard, vol. II (Boston: Ginn & Company, 1909), 45-48.

In the first decade of the second half of the eighteenth century James Hargreaves was a weaver at Standhill, near Blackburn. He is sometimes described as a carpenter, and probably he combined both trades. He was "a stout, broad-set man, about five feet ten inches high, or rather more"; and this is all that is known of him personally. The Blackburn of the well-to-do Peel and of the humble Hargreaves was a town of some 5000 inhabitants. It was noted for the production of "Blackburn greys," cloths of linen warp and cotton weft, which, before the introduction of calico printing into Lancashire by the first Robert Peel and others, were generally sent to London to undergo that decorative operation. Doubtless, in the district of the "Blackburn greys," Hargreaves must have seen and heard much about the demand for cotton yarn outstripping the supply, and about schemes to supersede or improve the rude and sluggish old one-thread spinning wheel.

Hargreaves is said to have received the original idea of his machine from seeing a one-thread wheel overturned upon the floor, when both the wheel and the spindle continued to revolve. The spindle was thus thrown from a horizontal into an upright position; and the thought seems to have struck him that if a number of spindles were placed upright, and side by side, several threads might be spun at once. He contrived a frame, in one part of which he placed eight rovings in a row, and in another part a row of eight spindles. The rovings, when extended to the spindles, passed between two horizontal bars of wood, forming a clasp, which opened and shut somewhat like a parallel ruler; when pressed together this clasp held the threads fast. A certain portion of roving being extended from the spindles to the wooden clasp, the clasp was closed and was then drawn along the horizontal frame to a considerable distance from the spindles, by which the threads were lengthened out and reduced to the proper tenuity. This was done with the spinner's left hand, and his right hand at the same time turned a wheel which caused the spindles to revolve rapidly, and thus the roving was spun into yarn. By returning the clasp to its first situation, and letting down a presser wire, the yarn was wound upon the spindle.

All, and more than all, that Kay's shuttle had done for the weaver, the jenny did for the spinner. If the fly shuttle doubled the productive power of the weaver, the jenny at once octupled the spinner's. The number of spindles in the jenny was at first eight; when Hargreaves obtained a patent it was sixteen; it soon rose to be twenty or thirty; and no less than one hundred have been used since. The jennies could be worked by children as well as, nay, better than, by adults. The awkward posture required to spin on them was discouraging to grown-up people, who saw with surprise children from nine to twelve years of age manage them with dexterity, whereby plenty was brought into families overburdened with children, and the poor weavers were delivered from the bondage in which they had lain from the insolence of spinners.

Nevertheless the usefulness of the jenny was of a restricted kind. It did not make the rovings, which had still to be spun on the ordinary wheel, and to be supplied to the jenny for conversion into yarn. Above all, the yarn spun by the jenny was fit only for weft, and unless a yarn hard enough for warp had been produced in other ways afterwards, there would have been no cotton manufacture strictly so called. But the revolution which the spinning jenny produced in the manufacture as it then existed was, of course, immense.

Hargreaves is supposed to have invented the jenny about 1764, and certainly by 1767 he had so far perfected it that a child could work eight spindles at once with it. When first invented it was doubtless a rude machine, and Hargreaves is said to have kept it a secret, and to have used it merely in his own family and his own business, to supply himself with weft for his looms. It was, of course, a secret which could not long be kept. If the jenny came into general use, the weaver would no longer be kept at the mercy of the spinner; the production of yarn would be multiplied, and its price would fall. The spinners of Blackburn, their fathers, brothers, sweethearts, were not students of political economy, and did not reflect that increased supply at a lower price would produce an increased demand. They looked only to the probable immediate effect of the jenny on the number of persons employed in spinning and on the price of yarn. The very weavers were dissatisfied, being afraid, it seems, "lest the manufacturers should demand finer weft woven at the former prices." The Blackburners rose upon Hargreaves, broke into his house, destroyed his jenny or jennies, and made the town and neighborhood too hot for him.

Hargreaves shook the dust from off his feet and fled the ungrateful district. He made for Nottingham, as a chief seat of the manufacture of silk and worsted stockings, and where that of cotton hosiery, though much valued, had languished for want of suitable yarn.

The Hegira of Hargreaves took place in 1767, in which very year Mr. Richard Arkwright, barber, of Bolton, had his earliest conferences with one Kay, a clock maker at Warrington, respecting the bending of some wires and the turning of some pieces of brass for a spinning machine he was building. Two years later, warned by the fate of Hargreaves, Mr. Arkwright, too, quietly migrated to Nottingham, and in the July of 1769 he "enrolled" the specification of his famous first patent for spinning by rollers.

Poor Hargreaves was to have no such successful career as that of the Bolton barber. After his arrival in Nottingham he worked for a while in the employment of Mr. Shipley, for whom he made some jennies secretly in his house. It was probably with the assistance of a Nottingham joiner by the name of James that Hargreaves was enabled, in the July of 1770, to take out a patent for his spinning jenny. Finding that several of the Lancashire manufacturers were using the jenny, Hargreaves gave notice of actions against them. The manufacturers met, and sent a delegate to Nottingham, who offered Hargreaves 3000 for permission to use the machine; but he at first demanded 7000, and at last stood out for 4000. The negotiations being broken off, the actions proceeded; but before they came to trial Hargreave's attorney was informed that his client, before leaving Lancashire, had sold some jennies to obtain clothing for his children (of whom he had six or seven); and in consequence of this, which was true, the attorney finally gave up the action in despair of obtaining a verdict.

Hargreaves, however, did not, like Kay, die in a foreign land, and in misery or poverty. The partnership business was carried on "with moderate success" until the death of Hargreaves on the 22nd of April, 1778, the year before that in which Samuel Crompton invented the mule.

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