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1 Barlow, Edward
SUBJECT AREA: Horology[br]baptized 15 December 1636 near Warrington, Cheshire, England d. 1716[br]English priest and mechanician who invented rack striking, repeating mechanisms for clocks and watches and, with others, patented a horizontal escapement for watches.[br]Barlow was the son of Edward Booth, but he adopted the surname of his godfather, the Benedictine monk Ambrose Barlow, as a condition of his will. In 1659 he entered the English College at Lisbon, and after being ordained a priest he was sent to the English mission. There he resided at Parkhall in Lancashire, the seat of Mr Houghton, with whom he later collaborated on the horizontal escapement.At a time when it was difficult to produce a light to examine the dial of a clock or watch at night, a mechanism that would indicate the hours and subdivisions of the hour audibly and at will was highly desirable. The count wheel, which had been used from the earliest times to control the striking of a clock, was unsuitable for this purpose as it struck the hours in sequence. If the mechanism was set off manually to determine the time, the strike would no longer correspond with the indications on the dial. In 1675 Barlow invented rack striking, where the hour struck was determined solely by the position of the hour hand. With this mechanism it was therefore possible to repeat the hour at will, without upsetting the sequence of striking. In 1687 Barlow tried to patent a method of repeating for watches, but it was rejected by James II in favour of a system produced by the watchmaker Daniel Quare and which was simpler to operate. He was successful in obtaining a patent for a horizontal escapement for watches in 1695, in collaboration with William Hough ton and Thomas Tompion. Although this escapement was little used, it can be regarded as the forerunner of the cylinder escapement that George Graham introduced c. 1725.[br]Bibliography1695 (with William Houghton and Thomas Tompion), British patent no. 344 (a horizontal escapement).Further ReadingDictionary of National Biography, 1885, Vol. 1, Oxford, S.V.Barlow.Britten's Old Clocks \& Watches and Their Makers, 1982, rev. Cecil Clutton, 9th edn, London, pp. 148, 310, 313 (provides a technical description of rack striking, repeating work and the horizontal escapement).DV -
2 Graham, George
SUBJECT AREA: Horology[br]b. c.1674 Cumberland, Englandd. 16 November 1751 London, England[br]English watch-and clockmaker who invented the cylinder escapement for watches, the first successful dead-beat escapement for clocks and the mercury compensation pendulum.[br]Graham's father died soon after his birth, so he was raised by his brother. In 1688 he was apprenticed to the London clockmaker Henry Aske, and in 1695 he gained his freedom. He was employed as a journeyman by Tompion in 1696 and later married his niece. In 1711 he formed a partnership with Tompion and effectively ran the business in Tompion's declining years; he took over the business after Tompion died in 1713. In addition to his horological interests he also made scientific instruments, specializing in those for astronomical use. As a person, he was well respected and appears to have lived up to the epithet "Honest George Graham". He befriended John Harrison when he first went to London and lent him money to further his researches at a time when they might have conflicted with his own interests.The two common forms of escapement in use in Graham's time, the anchor escapement for clocks and the verge escapement for watches, shared the same weakness: they interfered severely with the free oscillation of the pendulum and the balance, and thus adversely affected the timekeeping. Tompion's two frictional rest escapements, the dead-beat for clocks and the horizontal for watches, had provided a partial solution by eliminating recoil (the momentary reversal of the motion of the timepiece), but they had not been successful in practice. Around 1720 Graham produced his own much improved version of the dead-beat escapement which became a standard feature of regulator clocks, at least in Britain, until its supremacy was challenged at the end of the nineteenth century by the superior accuracy of the Riefler clock. Another feature of the regulator clock owed to Graham was the mercury compensation pendulum, which he invented in 1722 and published four years later. The bob of this pendulum contained mercury, the surface of which rose or fell with changes in temperature, compensating for the concomitant variation in the length of the pendulum rod. Graham devised his mercury pendulum after he had failed to achieve compensation by means of the difference in expansion between various metals. He then turned his attention to improving Tompion's horizontal escapement, and by 1725 the cylinder escapement existed in what was virtually its final form. From the following year he fitted this escapement to all his watches, and it was also used extensively by London makers for their precision watches. It proved to be somewhat lacking in durability, but this problem was overcome later in the century by using a ruby cylinder, notably by Abraham Louis Breguet. It was revived, in a cheaper form, by the Swiss and the French in the nineteenth century and was produced in vast quantities.[br]Principal Honours and DistinctionsFRS 1720. Master of the Clockmakers' Company 1722.BibliographyGraham contributed many papers to the Philosophical Transactions of the Royal Society, in particular "A contrivance to avoid the irregularities in a clock's motion occasion'd by the action of heat and cold upon the rod of the pendulum" (1726) 34:40–4.Further ReadingBritten's Watch \& Clock Maker's Handbook Dictionary and Guide, 1978, rev. Richard Good, 16th edn, London, pp. 81, 84, 232 (for a technical description of the dead-beat and cylinder escapements and the mercury compensation pendulum).A.J.Turner, 1972, "The introduction of the dead-beat escapement: a new document", Antiquarian Horology 8:71.E.A.Battison, 1972, biography, Biographical Dictionary of Science, ed. C.C.Gillespie, Vol. V, New York, 490–2 (contains a résumé of Graham's non-horological activities).DV -
3 Horology
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4 Johnson, Thomas
SUBJECT AREA: Textiles[br]fl. 1800s Englandd. after 1846[br]English developer of the sizing and beaming machine, and improver of the hand loom.[br]Thomas Johnson was an assistant to William Radcliffe c.1802 in his developments of the sizing machine and hand looms. Johnson is described by Edward Baines (1835) as "an ingenious but dissipated young man to whom he [Radcliffe] explained what he wanted, and whose fertile invention suggested a great variety of expedients, so that he obtained the name of the “conjuror” among his fellow-workmen". Johnson's genius, and Radcliffe's judgement and perseverance, at length produced the dressing-machine that was soon applied to power looms and made their use economic. Cotton warps had to be dressed with a starch paste to prevent them from fraying as they were being woven. Up to this time, the paste had had to be applied as the warp was unwound from the back of the loom, which meant that only short lengths could be treated and then left to dry, holding up the weaver. Radcliffe carried out the dressing and beaming in a separate machine so that weaving could proceed without interruption. Work on the dressing-machine was carried out in 1802 and patents were taken out in 1803 and 1804. These were made out in Johnson's name because Radcliffe was afraid that if his own name were used other people, particularly foreigners, would discover his secrets. Two more patents were taken out for improvements to hand looms. The first of these was a take-up motion for the woven cloth that automatically wound the cloth onto a roller as the weaver operated the loom. This was later incorporated by H.Horrocks into his own power loom design.Radcliffe and Johnson also developed the "dandy-loom", which was a more compact form of hand loom and later became adapted for weaving by power. Johnson was the inventor of the first circular or revolving temples, which kept the woven cloth at the right width. In the patent specifications there is a patent in 1805 by Thomas Johnson and James Kay for an improved power loom and another in 1807 for a vertical type of power loom. Johnson could have been involved with further patents in the 1830s and 1840s for vertical power looms and dressing-machines, which would put his death after 1846.[br]Bibliography1802, British patent no. 2,684 (dressing-machine).1803, British patent no. 2,771 (dressing-machine).1805, with James Kay, British patent no. 2,876 (power-loom). 1807, British patent no. 6,570 (vertical powerloom).Further ReadingThere is no general account of Johnson's life, but references to his work with Radcliffe may be found in A.Barlow, 1878, The History and Principles of Weaving by Hand and by Power, London; and in E.Baines, 1835, History of the Cotton Manufacture in Great Britain, London.D.J.Jeremy, 1981, Transatlantic Industrial Revolution. The Diffusion of Textile Technologies Between Britain and America, 1790–1830s, Oxford (for the impact of the dressing-machine in America).RLH -
5 Tompion, Thomas
SUBJECT AREA: Horology[br]baptized 25 July 1639 Ickwell Green, Englandd. 20 November 1713 London, England[br]English clock-and watchmaker of great skill and ingenuity who laid the foundations of his country's pre-eminence in that field.[br]Little is known about Tompion's early life except that he was born into a family of blacksmiths. When he was admitted into the Clockmakers' Company in 1671 he was described as a "Great Clockmaker", which meant a maker of turret clocks, and as these clocks were made of wrought iron they would have required blacksmithing skills. Despite this background, he also rapidly established his reputation as a watchmaker. In 1674 he moved to premises in Water Lane at the sign of "The Dial and Three Crowns", where his business prospered and he remained for the rest of his life. Assisted by journeymen and up to eleven apprentices at any one time, the output from his workshop was prodigious, amounting to over 5,000 watches and 600 clocks. In his lifetime he was famous for his watches, as these figures suggest, but although they are of high quality they do not differ markedly from those produced by other London watchmakers of that period. He is now known more for the limited number of elaborate clocks that he produced, such as the equation clock and the spring-driven clock of a year's duration, which he made for William III. Around 1711 he took into partnership his nephew by marriage, George Graham, who carried on the business after his death.Although Tompion does not seem to have been particularly innovative, he lived at a time when great advances were being made in horology, which his consummate skill as a craftsman enabled him to exploit. In this he was greatly assisted by his association with Robert Hooke, for whom Tompion constructed a watch with a balance spring in 1675; at that time Hooke was trying to establish his priority over Huygens for this invention. Although this particular watch was not successful, it made Tompion aware of the potential of the balance spring and he became the first person in England to apply Huygens's spiral spring to the balance of a watch. Although Thuret had constructed such a watch somewhat earlier in France, the superior quality of Tompion's wheel work, assisted by Hooke's wheel-cutting engine, enabled him to dominate the market. The anchor escapement (which reduced the amplitude of the pendulum's swing) was first applied to clocks around this time and produced further improvements in accuracy which Tompion and other makers were able to utilize. However, the anchor escapement, like the verge escapement, produced recoil (the clock was momentarily driven in reverse). Tompion was involved in attempts to overcome this defect with the introduction of the dead-beat escapement for clocks and the horizontal escapement for watches. Neither was successful, but they were both perfected later by George Graham.[br]Principal Honours and DistinctionsMaster of the Clockmakers' Company 1703.Bibliography1695, with William Houghton and Edward Barlow, British patent no. 344 (for a horizontal escapement).Further ReadingR.W.Symonds, 1951, Thomas Tompion, His Life and Work, London (a comprehensive but now slightly dated account).H.W.Robinson and W.Adams (eds), 1935, The Diary of Robert Hooke (contains many references to Tompion).D.Howse, 1970, The Tompion clocks at Greenwich and the dead-beat escapement', Antiquarian Horology 7:18–34, 114–33.DV
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