Arnold, Aza

SUBJECT AREA: Textiles

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b. 4 October 1788 Smithfield, Pawtucket, Rhode Island, USA

d. 1865 Washington, DC, USA

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American textile machinist who applied the differential motion to roving frames, solving the problem of winding on the delicate cotton rovings.

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He was the son of Benjamin and Isabel Arnold, but his mother died when he was 2 years old and after his father's second marriage he was largely left to look after himself. After attending the village school he learnt the trade of a carpenter, and following this he became a machinist. He entered the employment of Samuel Slater, but left after a few years to engage in the unsuccessful manufacture of woollen blankets. He became involved in an engineering shop, where he devised a machine for taking wool off a carding machine and making it into endless slivers or rovings for spinning. He then became associated with a cotton-spinning mill, which led to his most important invention. The carded cotton sliver had to be reduced in thickness before it could be spun on the final machines such as the mule or the waterframe. The roving, as the mass of cotton fibres was called at this stage, was thin and very delicate because it could not be twisted to give strength, as this would not allow it to be drawn out again during the next stage. In order to wind the roving on to bobbins, the speed of the bobbin had to be just right but the diameter of the bobbin increased as it was filled. Obtaining the correct reduction in speed as the circumference increased was partially solved by the use of double-coned pulleys, but the driving belt was liable to slip owing to the power that had to be transmitted.

The final solution to the problem came with the introduction of the differential drive with bevel gears or a sun-and-planet motion. Arnold had invented this compound motion in 1818 but did not think of applying it to the roving frame until 1820. It combined the direct-gearing drive from the main shaft of the machine with that from the cone-drum drive so that the latter only provided the difference between flyer and bobbin speeds, which meant that most of the transmission power was taken away from the belt. The patent for this invention was issued to Arnold on 23 January 1823 and was soon copied in Britain by Henry Houldsworth, although J.Green of Mansfield may have originated it independendy in the same year. Arnold's patent was widely infringed in America and he sued the Proprietors of the Locks and Canals, machine makers for the Lowell manufacturers, for $30,000, eventually receiving $3,500 compensation. Arnold had his own machine shop but he gave it up in 1838 and moved the Philadelphia, where he operated the Mulhausen Print Works. Around 1850 he went to Washington, DC, and became a patent attorney, remaining as such until his death. On 24 June 1856 he was granted patent for a self-setting and self-raking saw for sawing machines.

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Bibliography

28 June 1856, US patent no. 15,163 (self-setting and self-raking saw for sawing machines).

Further Reading

Dictionary of American Biography, Vol. 1.

W.English, 1969, The Textile Industry, London (a description of the principles of the differential gear applied to the roving frame).

D.J.Jeremy, 1981, Transatlantic Industrial Revolution. The Diffusion of Textile Technologies Between Britain and America, 1790–1830, Oxford (a discussion of the introduction and spread of Arnold's gear).

RLH