mechanical+watches

SUBJECT AREA: Horology

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Thomas Mudge was the son of a clergyman and schoolmaster who, recognizing his son's mechanical aptitude, apprenticed him to the eminent London clock-and watchmaker George Graham. Mudge became free of the Clockmakers' Company in 1738 and set up on his own account after Graham's death in 1751. Around 1755 he formed a partnership with William Dutton, another apprentice of Graham. The firm produced conventional clocks and watches of excellent quality, but Mudge had also established a reputation for making highly innovative individual pieces. The most significant of these was the watch with a detached-lever escapement that he completed in 1770, although the idea had occurred to him as early as 1754. This watch was purchased by George III for Queen Charlotte and is still in the Royal Collection. Shortly afterwards Mudge moved to Plymouth, to devote his time to the perfection of the marine chronometer, leaving the London business in the hands of Dutton. The chronometers he produced were comparable in performance to those of John Harrison, but like them they were too complicated and expensive to be produced in quantity.

Mudge's patron, Count Bruhl, recognized the potential of the detached-lever escapement, but Mudge was too involved with his marine chronometers to make a watch for him. He did, however, provide Bruhl with a large-scale model of his escapement, from which the Swiss expatriate Josiah Emery was able to make a watch in 1782. Over the next decade Emery made a limited number of similar watches for wealthy clients, and it was the performance of these watches that demonstrated the worth of the escapement. The detached-lever escapement took some time to be adopted universally, but this was facilitated in the nineteenth century by the development of a cheaper form, the pin lever.

By the end of the century the detached-lever escapement was used in one form or another in practically all mechanical watches and portable clocks. If a watch is to be a good timekeeper the balance must be free to swing with as little interference as possible from the escapement. In this respect the cylinder escapement is an improvement on the verge, although it still exerts a frictional force on the balance. The lever escapement is a further improvement because it detaches itself from the balance after delivering the impulse which keeps it oscillating.

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SUBJECT AREA: Horology

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Huygens was born into a cultured and privileged class. His father, Constantijn, was a poet and statesman who had wide interests. Constantijn exerted a strong influence on his son, who was educated at home until he reached the age of 16. Christiaan studied law and mathematics at Ley den University from 1645 to 1647, and continued his studies at the Collegium Arausiacum in Breda until 1649. He then lived at The Hague, where he had the means to devote his time entirely to study. In 1666 he became a Member of the Académie des Sciences in Paris and settled there until his return to The Hague in 1681. He also had a close relationship with the Royal Society and visited London on three occasions, meeting Newton on his last visit in 1689. Huygens had a wide range of interests and made significant contributions in mathematics, astronomy, optics and mechanics. He also made technical advances in optical instruments and horology.

Despite the efforts of Burgi there had been no significant improvement in the performance of ordinary clocks and watches from their inception to Huygens's time, as they were controlled by foliots or balances which had no natural period of oscillation. The pendulum appeared to offer a means of improvement as it had a natural period of oscillation that was almost independent of amplitude. Galileo Galilei had already pioneered the use of a freely suspended pendulum for timing events, but it was by no means obvious how it could be kept swinging and used to control a clock. Towards the end of his life Galileo described such a. mechanism to his son Vincenzio, who constructed a model after his father's death, although it was not completed when he himself died in 1642. This model appears to have been copied in Italy, but it had little influence on horology, partly because of the circumstances in which it was produced and possibly also because it differed radically from clocks of that period. The crucial event occurred on Christmas Day 1656 when Huygens, quite independently, succeeded in adapting an existing spring-driven table clock so that it was not only controlled by a pendulum but also kept it swinging. In the following year he was granted a privilege or patent for this clock, and several were made by the clockmaker Salomon Coster of The Hague. The use of the pendulum produced a dramatic improvement in timekeeping, reducing the daily error from minutes to seconds, but Huygens was aware that the pendulum was not truly isochronous. This error was magnified by the use of the existing verge escapement, which made the pendulum swing through a large arc. He overcame this defect very elegantly by fitting cheeks at the pendulum suspension point, progressively reducing the effective length of the pendulum as the amplitude increased. Initially the cheeks were shaped empirically, but he was later able to show that they should have a cycloidal shape. The cheeks were not adopted universally because they introduced other defects, and the problem was eventually solved more prosaically by way of new escapements which reduced the swing of the pendulum. Huygens's clocks had another innovatory feature: maintaining power, which kept the clock going while it was being wound.

Pendulums could not be used for portable timepieces, which continued to use balances despite their deficiencies. Robert Hooke was probably the first to apply a spring to the balance, but his efforts were not successful. From his work on the pendulum Huygens was well aware of the conditions necessary for isochronism in a vibrating system, and in January 1675, with a flash of inspiration, he realized that this could be achieved by controlling the oscillations of the balance with a spiral spring, an arrangement that is still used in mechanical watches. The first model was made for Huygens in Paris by the clockmaker Isaac Thuret, who attempted to appropriate the invention and patent it himself. Huygens had for many years been trying unsuccessfully to adapt the pendulum clock for use at sea (in order to determine longitude), and he hoped that a balance-spring timekeeper might be better suited for this purpose. However, he was disillusioned as its timekeeping proved to be much more susceptible to changes in temperature than that of the pendulum clock.

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SUBJECT AREA: Electronics and information technology, Horology

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Hetzel trained as an electrical engineer at the Federal Polytechnic in Zurich and worked for several years in the field of telecommunications before joining the Bulova Watch Company in 1950. At that time several companies were developing watches with electromagnetically maintained balances, but they represented very little advance on the mechanical watch and the mechanical switching mechanism was unreliable. In 1952 Hetzel started work on a much more radical design which was influenced by a transistorized tuning-fork oscillator that he had developed when he was working on telecommunications. Tuning forks, whose vibrations were maintained electromagnetically, had been used by scientists during the nineteenth century to measure small intervals of time, but Niaudet- Breguet appears to have been the first to use a tuning fork to control a clock. In 1866 he described a mechanically operated tuning-fork clock manufactured by the firm of Breguet, but it was not successful, possibly because the fork did not compensate for changes in temperature. The tuning fork only became a precision instrument during the 1920s, when elinvar forks were maintained in vibration by thermionic valve circuits. Their primary purpose was to act as frequency standards, but they might have been developed into precision clocks had not the quartz clock made its appearance very shortly afterwards. Hetzel's design was effectively a miniaturized version of these precision devices, with a transistor replacing the thermionic valve. The fork vibrated at a frequency of 360 cycles per second, and the hands were driven mechanically from the end of one of the tines. A prototype was working by 1954, and the watch went into production in 1960. It was sold under the tradename Accutron, with a guaranteed accuracy of one minute per month: this was a considerable improvement on the performance of the mechanical watch. However, the events of the 1920s were to repeat themselves, and by the end of the decade the Accutron was eclipsed by the introduction of quartz-crystal watches.

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SUBJECT AREA: Mechanical, pneumatic and hydraulic engineering, Textiles

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Richard Roberts was the son of a shoemaker and tollkeeper and received only an elementary education at the village school. At the age of 10 his interest in mechanics was stimulated when he was allowed by the Curate, the Revd Griffith Howell, to use his lathe and other tools. As a young man Roberts acquired a considerable local reputation for his mechanical skills, but these were exercised only in his spare time. For many years he worked in the local limestone quarries, until at the age of 20 he obtained employment as a pattern-maker in Staffordshire. In the next few years he worked as a mechanic in Liverpool, Manchester and Salford before moving in 1814 to London, where he obtained employment with Henry Maudslay. In 1816 he set up on his own account in Manchester. He soon established a reputation there for gear-cutting and other general engineering work, especially for the textile industry, and by 1821 he was employing about twelve men. He built machine tools mainly for his own use, including, in 1817, one of the first planing machines.

One of his first inventions was a gas meter, but his first patent was obtained in 1822 for improvements in looms. His most important contribution to textile technology was his invention of the self-acting spinning mule, patented in 1825. The normal fourteen-year term of this patent was extended in 1839 by a further seven years. Between 1826 and 1828 Roberts paid several visits to Alsace, France, arranging cottonspinning machinery for a new factory at Mulhouse. By 1826 he had become a partner in the firm of Sharp Brothers, the company then becoming Sharp, Roberts \& Co. The firm continued to build textile machinery, and in the 1830s it built locomotive engines for the newly created railways and made one experimental steam-carriage for use on roads. The partnership was dissolved in 1843, the Sharps establishing a new works to continue locomotive building while Roberts retained the existing factory, known as the Globe Works, where he soon after took as partners R.G.Dobinson and Benjamin Fothergill (1802–79). This partnership was dissolved c. 1851, and Roberts continued in business on his own for a few years before moving to London as a consulting engineer.

During the 1840s and 1850s Roberts produced many new inventions in a variety of fields, including machine tools, clocks and watches, textile machinery, pumps and ships. One of these was a machine controlled by a punched-card system similar to the Jacquard loom for punching rivet holes in plates. This was used in the construction of the Conway and Menai Straits tubular bridges. Roberts was granted twenty-six patents, many of which, before the Patent Law Amendment Act of 1852, covered more than one invention; there were still other inventions he did not patent. He made his contribution to the discussion which led up to the 1852 Act by publishing, in 1830 and 1833, pamphlets suggesting reform of the Patent Law.

In the early 1820s Roberts helped to establish the Manchester Mechanics' Institute, and in 1823 he was elected a member of the Literary and Philosophical Society of Manchester. He frequently contributed to their proceedings and in 1861 he was made an Honorary Member. He was elected a Member of the Institution of Civil Engineers in 1838. From 1838 to 1843 he served as a councillor of the then-new Municipal Borough of Manchester. In his final years, without the assistance of business partners, Roberts suffered financial difficulties, and at the time of his death a fund for his aid was being raised.

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SUBJECT AREA: Mechanical, pneumatic and hydraulic engineering

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Joseph Rogers Brown was the eldest son of David Brown, who was modestly established as a maker of and dealer in clocks and watches. Joseph assisted his father during school vacations and at the age of 17 left to obtain training as a machinist. In 1829 he joined his father in the manufacture of tower clocks at Pawtucket, Rhode Island, and two years later went into business for himself in Pawtucket making lathes and small tools. In 1833 he rejoined his father in Providence, Rhode Island, as a partner in the manufacture of docks, watches and surveying and mathematical instruments. David Brown retired in 1841.

J.R.Brown invented and built in 1850 a linear dividing engine which was the first automatic machine for graduating rules in the United States. In 1851 he brought out the vernier calliper, the first application of a vernier scale in a workshop measuring tool. Lucian Sharpe was taken into partnership in 1853 and the firm became J.R.Brown \& Sharpe; in 1868 the firm was incorporated as the Brown \& Sharpe Manufacturing Company.

In 1855 Brown invented a precision gear-cutting machine to make clock gears. The firm obtained in 1861 a contract to make Wilcox \& Gibbs sewing machines and gave up the manufacture of clocks. At about this time F.W. Howe of the Providence Tool Company arranged for Brown \& Sharpe to make a turret lathe required for the manufacture of muskets. This was basically Howe's design, but Brown added a few features, and it was the first machine tool built for sale by the Brown \& Sharpe Company. It was followed in 1862 by the universal milling machine invented by Brown initially for making twist drills. Particularly for cutting gear teeth, Brown invented in 1864 a formed milling cutter which could be sharpened without changing its profile. In 1867 the need for an instrument for checking the thickness of sheet material became apparent, and in August of that year J.R.Brown and L.Sharpe visited the Paris Exhibition and saw a micrometer calliper invented by Jean Laurent Palmer in 1848. They recognized its possibilities and with a few developments marketed it as a convenient, hand-held measuring instrument. Grinding lathes were made by Brown \& Sharpe in the early 1860s, and from 1868 a universal grinding machine was developed, with the first one being completed in 1876. The patent for this machine was granted after Brown's sudden death while on holiday.

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SUBJECT AREA: Horology, Telecommunications

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Alexander Bain was born into a crofting family in a remote part of Scotland. He was apprenticed to a watchmaker in Wick and during that time he was strongly influenced by a lecture on "Heat, sound and electricity" that he heard in nearby Thurso. This lecture induced him to take up a position in Clerkenwell in London, working as a journeyman clockmaker, where he was able to further his knowledge of electricity by attending lectures at the Adelaide Gallery and the Polytechnic Institution. His thoughts naturally turned to the application of electricity to clockmaking, and despite a bitter dispute with Charles Wheatstone over priority he was granted the first British patent for an electric clock. This patent, taken out on 11 January 1841, described a mechanism for an electric clock, in which an oscillating component of the clock operated a mechanical switch that initiated an electromagnetic pulse to maintain the regular, periodic motion. This principle was used in his master clock, produced in 1845. On 12 December of the same year, he patented a means of using electricity to control the operation of steam railway engines via a steam-valve. His earliest patent was particularly far-sighted and anticipated most of the developments in electrical horology that occurred during the nineteenth century. He proposed the use of electricity not only to drive clocks but also to distribute time over a distance by correcting the hands of mechanical clocks, synchronizing pendulums and using slave dials (here he was anticipated by Steinheil). However, he was less successful in putting these ideas into practice, and his electric clocks proved to be unreliable. Early electric clocks had two weaknesses: the battery; and the switching mechanism that fed the current to the electromagnets. Bain's earth battery, patented in 1843, overcame the first defect by providing a reasonably constant current to drive his clocks, but unlike Hipp he failed to produce a reliable switch.

The application of Bain's numerous patents for electric telegraphy was more successful, and he derived most of his income from these. They included a patent of 12 December 1843 for a form of fax machine, a chemical telegraph that could be used for the transmission of text and of images (facsimile). At the receiver, signals were passed through a moving band of paper impregnated with a solution of ammonium nitrate and potassium ferrocyanide. For text, Morse code signals were used, and because the system could respond to signals faster than those generated by hand, perforated paper tape was used to transmit the messages; in a trial between Paris and Lille, 282 words were transmitted in less than one minute. In 1865 the Abbé Caselli, a French engineer, introduced a commercial fax service between Paris and Lyons, based on Bain's device. Bain also used the idea of perforated tape to operate musical wind instruments automatically. Bain squandered a great deal of money on litigation, initially with Wheatstone and then with Morse in the USA. Although his inventions were acknowledged, Bain appears to have received no honours, but when towards the end of his life he fell upon hard times, influential persons in 1873 secured for him a Civil List Pension of £80 per annum and the Royal Society gave him £150.

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See also: Bakewell, Frederick C.

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SUBJECT AREA: Horology, Mechanical, pneumatic and hydraulic engineering

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Son of Revd John Hooke, minister of the parish, he was a sickly child who was subject to headaches which prevented protracted study. He devoted his time while alone to making mechanical models including a wooden clock. On the death of his father in October 1648 he was left £100 and went to London, where he became a pupil of Sir Peter Lely and then went to Westminster School under Dr Busby. There he learned the classical languages, some Hebrew and oriental languages while mastering six books of Euclid in one week. In 1653 he entered Christ Church College, Oxford, where he graduated MA in 1663, after studying chemistry and astronomy. In 1662 he was appointed Curator of Experiments to the Royal Society and was elected a Fellow in 1663. In 1665 his appointment was made permanent and he was given apartments in Gresham College, where he lived until his death in 1703. He was an indefatigable experimenter, perhaps best known for the invention of the universal joint named after him. The properties of the atmosphere greatly engaged him and he devised many forms of the barometer. He was the first to apply the spiral spring to the regulation of the balance wheel of the watch in an attempt to measure longitude at sea, but he did not publish his results until after Huygens's reinvention of the device in 1675. Several of his "new watches" were made by Thomas Tompion, one of which was presented to King Charles II. He is said to have invented, among other devices, thirty different ways of flying, the first practical system of telegraphy, an odometer, a hearing aid, an arithmetical machine and a marine barometer. Hooke was a small man, somewhat deformed, with long, lank hair, who went about stooped and moved very quickly. He was of a melancholy and mistrustful disposition, ill-tempered and sharp-tongued. He slept little, often working all night and taking a nap during the day. John Aubrey, his near-contemporary, wrote of Hooke, "He is certainly the greatest Mechanick this day in the World." He is said to have been the first to establish the true principle of the arch. His eyesight failed and he was blind for the last year of his life. He is best known for his Micrographia, or some Physiological Descriptions of Minute Bodies, first published in 1665. After the Great Fire of London, he exhibited a model for the rebuilding of the City. This was not accepted, but it did result in Hooke's appointment as one of two City Surveyors. This proved a lucrative post and through it Hooke amassed a fortune of some thousands of pounds, which was found intact after his death some thirty years later. It had never been opened in the interim period. Among the buildings he designed were the new Bethlehem (Bedlam) Hospital, the College of Physicians and Montague House.

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