Page images
PDF
EPUB

down), London, in 1641. Galileo applied a long pendulum to a clock in Venice in 1649. Soon after the introduction of the long pendulum, it was found to be affected by the variations of the temperature,- becoming longer in damp weather, and shorter in dry. To remedy this evil, in the year 1721, Graham invented a pendulum consisting of a steel rod, the bob a glass jar containing mercury; the expansion and contraction of the rod is compensated by the opposite expansion and contraction of the mercury in the bob. This pendulum was found to be very effective. Numerous pendulums have been contrived at various times, since that period, consisting of metallicrods, &c., expanding in opposite directions. About 35 years ago, a very simple and cheap compensating pendulum

was invented by Professor Bailey, Secretary of the Astronomical Society, London. The principle of Bailey's pendulum, is that of a rod of well-seasoned pine, varnished; the bob of lead, and cylindrical in shape, with a hole through the centre, into which the rod is inserted. The bob rests upon a nut at the bottom of the rod, and simultaneous expansion of the rod and bob counteract each other. The wheels of a clock may be finished with great precision and great care taken to reduce the friction, and the mechanism may be unexceptionable ; but it is all futile if a clock iš not furnished with a good compensating pendulum. A great many of the public clocks in this country, have been greatly neglected upon this important point. I have seen highly-finished clocks, with iron pendulum rods 18 feet long, and less; and in consequence of the great expansion and contraction of metal rods of so great a length, their variations from true time is considerable; for if a clock with an iron pendulum of the length' I have mentioned, is regulated to keep time in the summer, it will in the winter lose about five minutes per week. யே

The anchor escapement was invented by the celebrated Dr. Hook, and introduced by Clements, a London clockmaker, about the year 1680. This escapement, although very good in some respects, causes a retrograde movement in the wheels of the clock, and in consequence has been called the recoil escapement." Graham, to do away with the recoil in this escapement, invented the dead-beat escapement. The wheels in this escapement are kept in a state of rest or repose during the oscillations of the pendulum, except at the moment when it receives its impulse from the escape wheel. The pin-wheel dead-beat escapement is used by some of the best makers of turret clocks; for with this escapement, and a good compensating pendulum, a clock will keep time with a very little variation.

It is supposed that clocks with alarms or striking parts, were first used by monks to arouse them to their devotions. During the 17th century there existed a great taste for striking clocks, which caused the production of an endless variety of them. The repeating clocks were first invented by an English clergyman named Barlow, about the year 1766. The following story is in circulation concerning the late Duke of Bridgewater :- The Duke was one day passing through his works between the hours of one and two, and seeing some of his workmen lounging about, he asked them why they were not at their work? He was informed that they had not heard the clock strike one yet, and that they were “having their dinner-hour." 'He determined that they should not have such an excuse again, and caused the clock to be altered to strike thirteen at one o'clock; and if it has not been altered recently, it strikes that number at the present time. Paulinus, Bishop of Nola, in Campagnia, is said to have invented bells about the year 400; they were introduced into France about the year 500, and were used by the Greeks about the year 884. They were introduced into monasteries in the 8th century, and were general in Europe about the year 900. The first peal of bells is said to have been hung at Crowland Abbey, Lincolnshire, in 960. Bells are liable to be worn through in the two places where the clappers strike: to remedy this evil, Mr. W. L. Baker, a few years ago, invented a simple and ingenious plan, the principle of which is to cause the bell to rotate, by simply turning a worm actuating a worm--wheel fixed upon the crown of the bell. By this means one man is enabled to turn a bell in a few minutes, and present a fresh place for the hammer or clapper to strike upon. A modification of this plan has been adopted by Mr. Denison, for the Westminster Bell. I refer those curious upon bells, to a very able work by the Rev. W. Lukis, M.A., F.S.A., &c., published by J. H. Parker, London, and the authors there cited.

Cast-steel bells were invented by E. Riepe. There were some at the Paris Industrial Exhibition, 1855. The Legion of Honour was awarded, in addition to a gold medal, to their inventor. They are produced at a considerably less cost than bronze or brass bells, and the sound produced by them I consider is equal to that of those composed of the more costly metal. In many of the continental towns are clocks which indicate the various changes in the astronomical world, and actuating curious automaton figures. The most ingenious and intricate of all these, is acknowledged by all parties to be the famous clock at Strasburg Cathedral. This clock is composed of three parts, respectively dedicated to the measure of time, to the calendar, and to astronomical move. ments. Upon the external dial are indicated the hours, and their subdivisions, as well as the days in the week; it strikes the hours and quarters, and puts in motion divers allegorical figures such as the following A figure placed upon a balustrade, turns each hour a sand-glass placed in its hand. Á huge cock at the hour of twelve crows lustily; at the same period the Twelve Apostles appear in a procession, &c. &c. In the calendar are noted the months, days, and dominical letters; and the clock shews all the saint days in the year. The plate upon which these signs are marked revolves once in 365 days for the ordinary, and 366 for the leap-year. The moveable feasts which seem as if they followed no rule, are here obtained with a remarkable ingenuity, in the which all the elements of the ecclesiastical computation-the milesimal, the solar circle, the golden number and epacts combine, and produce for an unlimited period the results sought. At twelve o'clock at night on the 31st of December, the moveable feasts arrange themselves for action during the ensuing year. The third motion produces the motion of the heavenly bodies, the globe, the sun, moon, and the small planets : each and all perform their separate parts with perfection.

Many very curious clocks were invented in the 17th century; some actuated by balls running up and down inclined planes, and swallowed up by and traversing the bodies of brazen serpents; or descending in metallic grooves, to be thrown up by Archimedean screws; one was made to go simply by means of its own weight, and by the cord like a lamp to the ceiling: the winding consisted in merely pushing the clock up to the ceiling. In another, the dial formed the brim of a plate in which swam a tortoise, turning with the hour, and indicating it by magnetic attraction,

A clock was made for George the Third, for registering the fluctuations of the barometer by means of a pencil floating upon the surface of the mercury, aud made to traverse a card divided into 365 parts, and turned upon its centre once a year. Mr. Gauntlet, of Middlesborough-on-Tees, has lately introduced something similar, but of much greater simplicity, and which is coming into general use, for registering

and indicating the temperature, for heating and drying purposes. It is in a neat case, with metallic barometer, and eight days' clock. In 1845, Mungo Ponton, F.R.S., &c., read a paper before the Scottish Society of Arts, describing an invention by him for indicating by means of photography the fluctuations of the barometer, which would register every halfhour by means of clock-work, and which photographed upon prepared paper by means of gaslight the degree of temperature. I consider that this and many other contrivances for the purpose, have been superseded by the one before mentioned. A great many contrivances of clock-work have been invented at various times, for registering the number of paces performed by man or horse; for registering the number of miles travelled by a vehicle; the knots per hour of a ship; the revolutions of a steam engine; the number of impressions produced by a printing press; the revolutions of a turn-style ; tally machines in docks; the fall of rain, &c. Within the last thirty years, great improvements have taken place with regard to electric clocks. I believe there are at the present time some ordinary public clocks at Liverpool, the pendulums of which are all regulated simultaneously from one point by electricity.

Recent intelligence from Japan informs us that clocks are made there, which are equal in finish and performance to those made in this country; but information from that country must be looked upon with suspicion for the present, for I dare say many of you have read some of the glowing descriptions sent by a newspaper correspondent, of the manufactures, &c., of Japan, and the wonderful railway which existed in the interior; and which afterwards turned out to be nothing more than a toy, the production of some ingenious Yankee. Clocks for registering punctuality, and the neglect of it, have of late years been made in various forms. Of this description, Knight's patent may be mentioned, and de

« EelmineJätka »