horological

SUBJECT AREA: Horology

[br]

[br]

[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]

See also: Barlow, Edward; Guillaume, Charles-Edouard

SUBJECT AREA: Horology

[br]

[br]

[br]

John Harwood served an apprenticeship as a watch repairer in Bolton, and after service in the First World War he obtained a post with a firm of jewellers in Douglas, Isle of Man. He became interested in the self-winding wrist watch, not because of the convenience of not having to wind it, but because of its potential to keep the mainspring fully wound and to exclude dust and moisture from the watch movement. His experience at the bench had taught him that these were the most common factors to affect adversely the reliability of watches. Completely unaware of previous work in this area, in 1922 he started experimenting and two years later he had produced a serviceable model for which he was granted a patent in 1924. The watch operated on the pedometer principle, the mainspring being wound by a pivoted weight that oscillated in the watch case as a result of the motion of the arm. The hands of his watch were set by rotating the bezel surrounding the dial, dispensing with the usual winding/hand-setting stem which allowed dust and moisture to enter the watch case. He took the watch to Switzerland, but he was unable to persuade the watchmaking firms to produce it until he had secured independent finance to cover the cost of tooling. The Harwood Self-Winding Watch Company Ltd was set up in 1928 to market the watches, but although several thousand were produced the company became a victim of the slump and closed down in 1932. The first practical self-winding watch also operated on the pedometer principle and is attributed to Abraham-Louis Perrellet (1770). The method was refined by Breguet in France and by Recordon, who patented the device in England, but it proved troublesome and went out of fashion. There was a brief revival of interest in self-winding watches towards the end of the nineteenth century, but they never achieved great popularity until after the Second World War, when they used either self-winding mechanisms similar to that devised by Harwood or weights which rotated in the case.

[br]

SUBJECT AREA: Mechanical, pneumatic and hydraulic engineering

[br]

[br]

[br]

Phillips was educated in Paris, at the Ecole Polytechnic and the Ecole des Mines. In 1849 he was awarded a doctorate in mathematical sciences by the University of Paris. He had a varied career in industry, academic and government institutions, rising to be Inspector- General of Mines in 1882.

It was well known that the balance of a watch or chronometer fitted with a simple spiral or helical spring was not isochronous, i.e. the period of the oscillation was not entirely independent of the amplitude. Watch-and chronometer-makers, notably Breguet and Arnold, had devised empirical solutions to the problem by altering the curvature of the end of the balance spring. In 1858 Phillips was encouraged to tackle the problem mathematically, and two years later he published a complete solution for the helical balance spring and a partial solution for the more complex spiral spring. Eleven years later he was able to achieve a complete solution for the spiral spring by altering the curvature of both ends of the spring. Phillips published a series of typical curves that the watch-or chronometer-maker could use to shape the ends of the balance spring.

[br]

SUBJECT AREA: Horology

[br]

[br]

[br]

Shortt entered the Engineering Department of the London and South Western Railway as an engineering cadet in 1902, remaining with the company and its successors until he retired in 1946. He became interested in precision horology in 1908, when he designed an instrument for recording the speed of trains; this led to a long and fruitful collaboration with Frank HopeJones, the proprietor of the Synchronome Company. This association culminated in the installation of a free-pendulum clock, with an accuracy of the order of one second per year, at Edinburgh Observatory in 1921. The clock's performance was far better than that of existing clocks, such as the Riefler, and a slightly modified version was produced commercially by the Synchronome Company. These clocks provided the time standard at Greenwich and many other observatories and scientific institutions across the world until they were supplanted by the quartz clock.

The period of a pendulum is constant if it swings freely with a constant amplitude in a vacuum. However, this ideal state cannot be achieved in a clock because the pendulum must be impulsed to maintain its amplitude and the swings have to be counted to indicate time. The free-pendulum clock is an attempt to approach this ideal as closely as possible. In 1898 R.J. Rudd used a slave clock, synchronized with a free pendulum, to time the impulses delivered to the free pendulum. This clock was not successful, but it provided the inspiration for Shortt's clock, which operates on the same principle. The Shortt clock used a standard Synchronome electric clock as the slave, and its pendulum was kept in step with the free pendulum by means of the "hit and miss" synchronizer that Shortt had patented in 1921. This allowed the pendulum to swing freely (in a vacuum), apart from the fraction of a second in which it received an impulse each half-minute.

[br]

See also: Marrison, Warren Alvin

SUBJECT AREA: Horology, Telecommunications

[br]

[br]

[br]

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.

[br]

See also: Bakewell, Frederick C.

DV / KF

SUBJECT AREA: Horology

[br]

[br]

[br]

Born Edmund Beckett Denison, he was educated at Eton and Trinity College, Cambridge, where he studied mathematics, graduating in 1838. He was called to the Bar in 1841 and became a Queen's Counsel in 1854. He built up a large and lucrative practice which gave him the independence to pursue his many interests outside law. His interest in horology may have been stimulated by a friend and fellow lawyer, J.M. Bloxham, who interestingly had invented a gravity escapement with an affinity to the escapement eventually used by Denison. Denison studied horology with his usual thoroughness and by 1850 he had published his Rudimentary Treatise on Clock and Watchmaking. It was natural, therefore, that he should have been invited to be a referee when a disagreement arose over the design of the clock for the new Houses of Parliament. Typically, he interpreted his brief very liberally and designed the clock himself. The most distinctive feature of the clock, in its final form, was the incorporation of a gravity escapement. A gravity escapement was particularly desirable in a public clock as it enabled the pendulum to receive a constant impulse (and thus swing with a constant amplitude), despite the variable forces that might be exerted by the wind on the exposed hands. The excellent performance of the prestigious clock at Westminster made Denison's form of gravity escapement de rigueur for large mechanical public clocks produced in Britain and in many other countries. In 1874 he inherited his father's baronetcy, dropping the Denison name, but later adopted the name Grimthorpe when he was created a Baron in 1886.

[br]

SUBJECT AREA: Horology, Metallurgy

[br]

[br]

[br]

Guillaume came from a family of clock-and watchmakers. He was educated at the Gymnasium in Neuchâtel and at Zurich Polytechnic, from which he received his doctorate in 1883 for a thesis on electrolytic capacitors. In the same year he joined the International Bureau of Weights and Measures at Sèvres in France, where he was to spend the rest of his working life. He retired as Director in 1936. At the bureau he was involved in distributing the national standards of the metre to countries subscribing to the General Conference on Weights and Measures that had been held in 1889. This made him aware of the crucial effect of thermal expansion on the lengths of the standards and he was prompted to look for alternative materials that would be less costly than the platinum alloys which had been used. While studying nickel steels he made the surprising discovery that the thermal expansion of certain alloy compositions was less than that of the constituent metals. This led to the development of a steel containing about 36 per cent nickel that had a very low thermal coefficient of expansion. This alloy was subsequently named "invar", an abbreviation of invariable. It was well known that changes in temperature affected the timekeeping of clocks by altering the length of the pendulum, and various attempts had been made to overcome this defect, most notably the mercury-compensated pendulum of Graham and the gridiron pendulum of Harrison. However, an invar pendulum offered a simpler and more effective method of temperature compensation and was used almost exclusively for pendulum clocks of the highest precision.

Changes in temperature can also affect the timekeeping of watches and chronometers, but this is due mainly to changes in the elasticity or stiffness of the balance spring rather than to changes in the size of the balance itself. To compensate for this effect Guillaume developed another more complex nickel alloy, "elinvar" (elasticity invariable), whose elasticity remained almost constant with changes in temperature. This had two practical consequences: the construction of watches could be simplified (by using monometallic balances) and more accurate chronometers could be made.

[br]

See also: Le Roy, Pierre

SUBJECT AREA: Electronics and information technology, Horology

[br]

[br]

[br]

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.

[br]

SUBJECT AREA: Mechanical, pneumatic and hydraulic engineering

[br]

[br]

[br]

John Jacob Holtzapffel was the second son of Charles Holtzapffel and was educated at King's College School, London, and at Cromwell House, Highgate. Following the death of his father in 1847 and of his elder brother, Charles, at the age of 10, he was called on at an early age to take part in the business of lathe-making and turning founded by his grandfather. He made many improvements to the lathe for ornamental turning, but he is now remembered chiefly for the continuation of his father's publication Turning and Mechanical Manipulation. J.J. Holtzapffel produced the fourth volume, on Plain Turning, in 1879, and the fifth, on Ornamental Turning, in 1884. In 1894 he revised and enlarged the third volume, but the intended sixth volume was never completed. J.J.Holtzapffel was admitted to the Turners' Company of London in 1862 and became Master in 1879. He was associated with the establishment of the Turners' Competition to encourage the art of turning and was one of the judges for many years. He was also an examiner for the City and Guilds of London Institute and the British Horological Institute. He was a member of the Society of Arts and a corresponding member of the Franklin Institute of Philadelphia. He was elected an Associate of the Institution of Civil Engineers in 1863 and became an Associate Member after reorganization of the classes of membership in 1878.

[br]

SUBJECT AREA: Horology

[br]

[br]

[br]

Le Roy was born into a distinguished horological family: his father, Julien, was Clockmaker to the King. Pierre became Master in 1737 and continued to work with his father, taking over the business when his father died in 1759. However, he seems to have left the commercial side of the business to others so that he could concentrate on developing the marine chronometer. Unlike John Harrison, he believed that the solution lay in detaching the escapement from the balance, and in 1748 he submitted a proposal for the first detached escapement to the Académie des Sciences in Paris. He also differed from Harrison in his method of temperature compensation, which acted directly on the balance by altering its radius of gyration. This was achieved either by mounting thermometers on the balance or by using bimetallic strips which effectively reduced the diameter of the balance as the temperature rose (with refinements, this later became the standard method of temperature compensation in watches and chronometers). Le Roy had already discovered that for every spiral balance spring there was a particular length at which it would be isochronous, and this method of temperature compensation did not destroy that isochronism by altering the length, as other methods did. These innovations were incorporated in a chronometer with an improved detached escapement which he presented to Louis XV in 1766 and described in a memoir to the Académie des Sciences. This instrument contained the three essential elements of all subsequent chronometers: an isochronous balance spring, a detached escapement and a balance with temperature compensation. Its performance was similar to that of Harrison's fourth timepiece, and Le Roy was awarded prizes by the Académie des Sciences for the chronometer and for his memoir. However, his work was never fully appreciated in France, where he was over-shadowed by his rival Ferdinand Berthoud. When Berthoud was awarded the coveted title of Horloger de la Marine, Le Roy became disillusioned and shortly afterwards gave up chronometry and retired to the country.

[br]

SUBJECT AREA: Electronics and information technology, Horology

[br]

[br]

[br]

Marrison received his high-school education at Kingston Collegiate Institute, Ontario, and in 1914 he entered Queen's University in Kingston. He graduated in Engineering Physics in 1920, his college career having been interrupted by war service in the Royal Flying Corps. During his service in the Flying Corps he worked on radio, and when he returned to Kingston he established his own transmitter. This interest in radio was later to influence his professional life.

In 1921 he entered Harvard University, where he obtained an MA, and shortly afterwards he joined the Western Electric Company in New York to work on the recording of sound on film. In 1925 he transferred to Western Electric's Bell Laboratory, where he began what was to become his life's work: the development of frequency standards for radio transmission. In 1922 Cady had used the elastic vibration of a quartz crystal to control the frequency of a valve oscillator, but at that time there was no way of counting and displaying the number of vibrations as the frequency was too high. In 1927 Marrison succeeded in dividing the frequency electronically until it was low enough to drive a synchronous motor. Although his purpose was to determine the frequency accurately by counting the number of vibrations that occurred in a given time, he had incidentally produced the first quartz-crystal -ontrolled clock. The results were sufficiently encouraging for him to build an improved version the following year, specifically as a time and frequency standard.

[br]