Clocks
It has been a matter of no small dispute as to who first invented clocks employing a weight for the motive power. Pacificus, Archdeacon of Verona, is said to have constructed a clock in 850 A. D., which marked, besides the hours, the days of the week, the phases of the moon, etc. Bailly, in his history of Modern Astronomy, argues very forcibly in favor of Pacificus, saying that he was the inventor of an escapement, in which the inertia of a balance was employed to retard and regulate the movement of a train of wheels moved by a weight. Father Alexandre, the author of a treatise on clocks, decides against Pacificus as the inventor of the weight clock, and Berthoud is of the same opinion. Nelthropp, in his treastise on watch work, says that it is more than probable, almost certain, that to the Moors of Spain the world is indebted for the great advance in clock work, and that from Cordova, Granada and Barcelona went forth the ideas which gave birth to the weight as a motive power, instead of water. Nelthropp is of the opinion that the inventor of the weight clock was one Gerbert, who was born in 920, A. D., in the village of Belliac in Auvergne. Certain it is that in 996 he made a clock for Madgeburg, which writers agree in stating had a weight for the motive power. After various ups and downs he became Pope, under the name of Sylvester II., in the year 999.
According to Stowe, a clock was erected near Westminister Hall, out of a fine of 800 marks imposed upon Ralph de Heugham, Chief Justice of the King's Bench, in 1288, A. D. In 1292 a clock was erected in Canterbury Cathedral, by Henry, the Prior. In 1317, a clock was erected in Exeter Cathedral. In 1326, Richard Wallingford, Abbot of St. Albans, constructed for the abbey a clock, which, Leland says, showed the course of the sun, moon and planets, and the rise and fall of the tides. In 1344 a clock was constructed for Padua by a workman named Antoine, after the designs of Jacques de Dondis. In 1348, a clock was constructed for Dover Castle, with wheels and frame of wrought iron; escapement, a crown wheel acting on pallets fixed to a verge, the upper end of which was suspended to a cock by a piece of cord, so as to hang perpendicular; lower end, a pivot working into a kind of stud attached to frame; balance, an iron bar, each end terminating in an elbow, to which a weight was attached in order to produce an equilibrium.
The first Strasburg clock was begun in 1352, and completed two years after, by John Bishop, of Lichtenberg. The second clock was begun in 1547, by Dr. Michael Heer, Nicholas Bruckner and Christian Herlin, professor of the University of Strasburg, and one of the most distinguished mathematicians of his time. Owing to the death of the Colleagues of Herlin, the work was not completed until 1574. In 1570, Conrad Dasypodius, a disciple of Herlin, reconstructed it on a larger scale. The mechanical work was performed by Isaac and Josiah Habrecht, clock-makers of Schaffhausen, Switzerland. This clock, which was restored in 1669, by Michael Isaac Habrecht, grandson of Dasypodius, one of the original makers, and a second time restored by James Straubharr, in 1732, ceased to act in 1789. The present Strasburg clock was commenced June 24, 1838, and started running on October 2, 1842.
In 1370, Charles V., King of France, caused to be made at Paris, a large turret clock, by one Henry de Vick, (sometimes spelled De Wyck), a clockmaker of Wurtemburg. He took eight years to complete the work. John Jouvance cast the bell on which the hammer of the clock struck the hours. It was on this signal was given for the massacre of Saint Bartholomew, 1572. The escape wheel of this clock was a crown wheel which acted on pallets attached to a vertical rod or axis, moving on two pivots; the balance, a heavy bar of iron, was fixed to the upper part of this verge, and had weights placed at corresponding distances on each arm by means of a number of equidistant notches, in order to regulate its vibrations. The upper end of the verge was suspended by a small cord, to a cock fixed to the larger cock, in which the pivot hole was pierced, for the purpose of keeping it perpendicular and decreasing the friction of the lower pivot.
In 1391, a clock was constructed for the Cathedral of Metz. In 1401, a clock was constructed for the Cathedral of Seville.
In the National Horogical Museum, at Nuremburg, Germany, is a clock which was presented to the museum by Gustav Speckhart, the court watchmaker. Speckhart estimates that it was made between the years 1400 and 1420, and is therefore the oldest clock in the city of Nuremburg. It was originally located upon the clock-tower of the St. Sebaldus Church, and indicated the hours to a watchman, who thereupon announced them to the inhabitants of the city by striking upon a bell in the tower. The hammer used weighed 120 pounds, and was introduced at the same time as the great bell Benedicta, in the year 1392. This clock is constructed entirely of iron, and is 15 3/4 inches high. The dial, which is also constructed of iron, is 11 inches in diameter. The clock when first discovered had a painted dial with twelve hours upon it, but Speckhart was aware that this was not the original dial because on the outer circumference of the dial, he found sixteen nails, one with a sharp pointed head, corresponding to the figure 12 and fifteen with round heads. On carefully removing this paint, he found another dial with twelve hours recorded, and on removing this he came upon the original dial which was painted with sixteen Roman figures of a gothic form. The original division of the day and night was into 16 hours, since the longest day, as well as the longest night, has sixteen hours. It is supposed that the nails were used by the watchman in determining the hour without the use of a light, and that he first sought the nail with the point, then felt downwards, counting the others, until he arived at the nail above which the hand rested. When the day was divided into twice twelve hours, about 1560-1580, the old hour wheel was removed and replaced by a new one, and the dial was repainted to correspond. The clock has no striking work proper, but as shown in Fig. 92, is provided with a kind of alarm, which after each hour, rattles the hammer to and fro on a bell, to call the attention of the watchman. The motion work consists of a barrel wheel with ninety-six teeth; a vertical wheel with thirty-five teeth, and a five-leaf pinion. The barrel wheel has a four-leaf pinion, seizing into forty-eight teeth of the hour wheel. In the former division of sixteen hours the hour wheel had sixty-four teeth.
The verge is suspended by a cord, and in lieu of a balance, is provided with a horizental toothed bar, on the ends of which hang two small weights, for regulating purposes. The winding part is peculiar, because, while the cord with the heavy weight descends, another cord with a small weight winds up in an opposite direction; and it is only necessary to draw down the small weight in order to wind up the heavier.
A pin a is inserted in the barrel wheel, which makes one revolution every hour; this pin unlocks the lever b and actuates the alarm; but since it was thought necessary to prolong the alarm for about one-quarter of a minute, the following arrangement was introduced: While the lever b on the movable part c, is raised up by the pin a, it liberates the wedge d, which, when the alarm is at rest, leans on the lever arm e, so that the alarm wheel, with one winding, sets the hammer into activity. Ordinarily it would take some time for the pin a, with its movable part c, to pass the lever b, and the alarm would in consequence run down with the first ringing. To prevent this, the angle i is riveted to the circumference of the alarm wheel, opposite to the wedge d, which after a half revolution of said wheel, still lifts up a part of the lever arm e, so that the part c falls downward by its own weight, and leaves the pin a free, so that the lever arm e again assumes its place upon the face of the alarm wheel, and the wedge d, in its further half revolution, places itself against it in order to place the alarm into repose, until the performance is again repeated.
An astrological clock, bearing the date 1525, is in the museum of the Society of Antiquaries, London. It was made by one Jacob Zech, of Prague, and Nelthropp, after investigation, is of the opinion that it was once the property of Sigismund the First, King of Poland. The wheels of this clock are made of iron. It is fitted with a powerful expansive spring, coiled in a drum or barrel, and has a hand-made fusee for equalizing the variable power. The balance consists of an iron bar carrying a screw at each of the ends, with tapped weights of lead. At present the barrel is connected with the fusee by a chain, but there is every reason to believe that in the original construction a catgut or cord was used. The escapement is of the verge and crown wheel type.
In 1532, Henry, the Eighth, presented to Anne Boleyn, on their marriage, a clock of beautiful construction which is now in Windsor Castle. There is a clock at Hampton Court Palace bearing the date 1540, and the initials N. O. There is a clock at Berne, Switzerland, constructed by Gaspard Brunner, a locksmith, but improved and repaired by Angely, a French clock-maker, in 1686. In 1758 James Ferguson invented what was known as the "Simple Clock." Fig. 93 illustrates the dial and wheel work of this clock. It showed the hours, minutes and seconds, by means of only three wheels and two pinions. The great wheel contained 120 teeth and turned around in twelve hours, and on its axis was the plate on which the twelve hours were engraved. This wheel turned a pinion of ten leaves and the minute hand was on the axis of this pinion. On this axis was also a wheel of 120 teeth which geared into a pinion of six leaves, and on the axis of this pinion was a wheel of 90 teeth, going around in three minutes and keeping a pendulum in motion that vibrated seconds, by pallets, as in a common clock, where the scape wheel has thirty teeth and revolves in a minute. As this wheel only revolved in three minutes it was necessary, in order to show the seconds, that a thin plate be fastened to the axis and divided into 180 equal parts, and divided as shown in the illustration, 10, 20, 30, 40, 50, 60; 10, 20, 30, etc. Annual and 400 Day Clocks. These clocks are made to run much longer than usual with one winding, by simply interposing a number of gears and pinions between the barrel and the usual train, and using a longer and stronger spring to overcome the increased friction in the train. These clocks are usually provided with torsion pendulums. They are made chieflly as curiosities.