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one more sure
In one of the comedies of Plautus, an old writer, he causes a Parasite to declaim as follows:
“The gods confound the man who first found out
How to distinguish hours ; confound him, too,
Shrunk up with hunger, creep along the street.” There is a sun-dial at Stubb Hall, Linn of Campsey, near Perth, which, from the inscription upon it, appears to have been erected by John Earl Percy, in the year 1578. It is in the form of an elegant pillar; at the upper part there are four dials for indicating the time, facing the points of the compass, respectively north, east, south, and west; lower down the pillar there are four more dials, looking north-east, northwest, south-east, and south-west ;-thus indicating upon eight separate dials.
It has been said that the regular motion of dropping water applied for indicating time, was in use before the introduction of sun-dials. There is no evidence to prove this assertion; but it is very certain that Clepsydra, or Water Clocks, were used by the inhabitants of China, Judæa, Chaldea, Egypt, and Greece, from a very remote period; and when Julius Cæsar brought his arms into Britain, he found them here, and by their means observed that the nights in this country were shorter than in Italy. The principle of the Clepsydra was as follows in a wood frame were two vessels, one placed above the other; in the bottom of the upper vessel was a small aperture; the lower vessel contained a wood float with a cord attached to it, which cord passed over a pulley with indications upon it. Their mode of action was as follows :—The upper vessel was filled with water, and the water passing through the small aperture into the lower vessel, caused the float to rise, and thereby actuate the pulley with the indications upon it. There were a great many descriptions of Clepsydra, differing in construction only, but not in principle, from the one I have mentioned. It may be interesting to note that at the present day a similar apparatus with float and indicating pulley, is in use for indicating the fluctuation of water in steam boilers. Plato is said to have invented a Clepsydra producing musical sounds, to indicate the hour of the night, when darkness prevented the dial from being seen. Pliny informs us that a Clepsydra was brought from the East by Pompey, and by it the speeches of the Roman orators were limited. And I think it would considerably facilitate business if some such method could be brought to bear upon some of the verbose legislators in the British Senate, -obtaining (as the patentees of improved steam engines have it) "greater speed with less consumption of fuel."
The sand-glass is said to have been first used in Alexandria, about B.C. 140; and no doubt its form is familiar to most of you. In consequence of its cheapness, portability, and simplicity, it has continued in use in this country up to a very recent date. At the present day the sand-glass is in use as an egg-boil. ing indicator : they are also used for philosophical experiments, and for indicating for a ship's log line at sea.
Alfred the Great, a man of keen perception, knew that division of labour was half the labour done. He divided his day into three parts of eight hours each the first he devoted to sleep, to meals, and to exercise; eight hours were absorbed by affairs of government; and eight were given to study and devotion. Alfred indicated his time by the constant
burning of candles, which were all made of one regular size and weight: they were notched upon the stem at regular distances. These candles were 12 inches long: six of them, or 72 inches of wax, were consumed in 24 hours or 1440 minutes; and thus supposing the notches at intervals of one inch, one inch would mark the lapse of 20 minutes. It appears that the candles were placed under the special care of his mass priest or chaplain. It was soon disco. vered that the wind rushing through the window and door, and numerous chinks in the wall of his palace, consumed the wax in an irregular manner. Nothing daunted, Alfred soon overcame this difficulty: he discovered that thin sheets of horn were transparent; accordingly, with this material and wood, he constructed a case for his candles, and hence the inventor of horn lanterns is said to be Alfred.
In the Crystal Palace, Sydenham, are some clocks manufactured by a firm called “The London Atmospheric Clock Company.” The clocks are similar to a thermometer; a glass tube with a short column of mercury in it, is placed upon a board with indications upon it; the descent of the mercury in the tube indicates the hour of the day,-quarter hours being the smallest interval indicated by those I saw. When the mercury falls to the bottom of the tube, it is reversed in a similar way to that of a sand-glass. These clocks are made and finished in a very neat style, and display considerable ingenuity. They are sold for about 5s. each; but as time indicators, in my opinion, they are a retrograde movement.
The information respecting the first clocks indicating by means of weights and wheels, is of a scanty nature. Gesner, an old English writer, says that in 1326, Richard of Wallingford, Abbot of St. Albans, "by a miracle of art" constructed a clock which had not its equal in Europe, and was called “Albion" by its inventor. Captain Smith, in a communication to the Antiquarian Society, in 1851, states that there is at present in Dover Castle a clock bearing the date of 1348. Charles the Fifth, surnamed the Wise, of France, caused a clock to be made for his palace, by De Vick, a German. This clock had a crown wheel escapement, similar to that of a bottle-jack at the present day. In 1382, upon the French entering the city of Cortray, the Duke of Burgundy ordered a clock which struck the hours to be taken away: it is at present at Notre Dame. The workmanship of these early clocks was of so rude a character, that minutes were too small for them to indicate; in fact, most of the ancient clocks were made with the hour hand only. There is a clock in the church of Rye, the dial of which is rather less than 8 feet in diameter. It strikes the hours and quarters, and has a pendulum 18 feet long; the bob is of lead, and weiglıs about 56lbs. There is a tradition in the town that this clock was taken from the Spanish Armada, in the year 1588, and presented to the town by Queen Elizabeth. This cannot be founded on fact, as will be seen from the following extract:“1513.—-Paid the cooper for a barrel for the chime 6 2 1515.-For working upon the frame and dial of
the clock in the steeple..
clock-work, in full payment of his
..0 6 8 1561.-For making the chimes to ring
..0 16 There is every reason to believe that the pendulum is an addition to the clock since the above dates, and that it formerly had a crown wheel escapement, similar to that in De Vick's clock: it is now going. I am indebted to the courtesy of W. Holloway, Esq., of Rye, for the foregoing particulars.
The long pendulum, as used at the present day, is said to have been first applied to a clock, and placed in the tower of St. Paul's Church (since burnt
0 2 0
1 16 0
The house over the clock ..
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 tempe. rature,- 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 metallic rods, &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 is 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.