It is evident that whenever it costs as much labour to produce
 a machine as is saved by the employment of that machine, there is nothing
 but a transposition of labour; consequently the total labour required to 369produce
 a commodity is not lessened or the productiveness of labour is not increased.
 It is clear, however, that the difference between the labour a machine
 costs, and the labour it saves, in other words, that the degree of its
 productiveness does not depend on the difference between its own value
 and the value of the implement it replaces. As long as the labour spent
 on a machine, and consequently the portion of its value added to the product,
 remains smaller than the value added by the workman to the product with
 his tool, there is always a difference of labour saved in favour of the
 machine. The productiveness of a machine is therefore measured by the human
 labour-power it replaces. According to Mr. Baynes, 2 operatives are required for the 450 mule spindles, inclusive of preparation machinery, [28] that are driven by one-horse power; each self-acting mule spindle, working ten hours, produces 13 ounces of yarn (average number of thickness); consequently 2½ operatives spin weekly 365 5/8 lbs. of yarn. Hence, leaving waste
 on one side, 366 lbs. of cotton absorb, during their conversion into yarn,
 only 150 hours’ labour, or fifteen days’ labour of ten hours each. But
 with a spinning-wheel, supposing the hand-spinner to produce thirteen ounces
 of yarn in sixty hours, the same weight of cotton would absorb 2,700 days’
 labour of ten hours each, or 27,000 hours’ labour. [29] Where blockprinting, the old method of printing calico by hand, has been superseded by machine printing, a single machine prints, with the aid of
 one man or boy, as much calico of four colours in one hour, as it formerly
 took 200 men to do. [30] Before Eli Whitney invented
 the cotton gin in 1793, the separation of the seed from a pound of cotton
 cost an average day’s labour. By means of his invention one negress was
 enabled to clean 100 lbs. daily; and since then, the efficacy of the gin
 has been considerably increased. A pound of cotton wool, previously costing
 50 cents to produce, included after that invention more unpaid labour,
 and was consequently sold with greater profit, at 10 cents. In India they 370employ
 for separating the wool from the seed, an instrument, half machine, half
 tool, called a churka; with this one man and a woman can clean 28 lbs.
 daily. With the churka invented some years ago by Dr. Forbes, one man and
 a boy produce 250 lbs. daily. If oxen, steam, or water, be used for driving
 it, only a few boys and girls as feeders are required. Sixteen of these
 machines driven by oxen do as much work in a day as formerly 750 people
 did on an average. [31]