CHAPTER XXV.

HOROLOGY AND INSTRUMENTS OF PRECISION.

Time Measuring Instruments of Antiquity.--Sun-dial.--Clepsydra, Hour-glass, Graduated Candle.--Plato’s Bell.--The Clepsydra of Ctesibius.--Incense Sticks of Chinese.--Sun-dials of Greeks and Romans.--Candles of Alfred the Great.--Wonderful Clocks of the Middle Ages.--Henry de Vick of France, 1370.--Two Hundred Years without Advance.--Astronomers, Brache and Valherius.--1525, Zech’s Fusee.--Progenitors of Modern Watch, 1500.--1582, Swinging Lamp of Galileo.--1639, Galileo’s Book.--Huygens and the Pendulum.--Dr. Hooke’s and David Ramsey’s Inventions.--Hair-Spring Balances.--George the Third’s Small Time-Piece.--Eighteenth Century Division of Time Pieces into Hours, Minutes and Seconds.--Stem Winders.--Astronomical Discoveries and Chronometers.--Dutch, Leading Clockmakers; Germany, Switzerland.--Systems Followed in these Countries.-- Minute Sub-divisions of Labour.--Watch and Clock Making in the United States.--American System.--Wonderful Machines for every Part.--Watch factories.--Pope’s Simile.--Revolution in Nineteenth Century.--Electric System.--4000 Patents in U.S. since 1800.--Registering Devices.--“A Mechanical Conscience.”-- Cash Registers.--Voting Machines.--Electrical Recorders.-- Cyclometers.--Speed Indicators.--Weighing Scales and Machines, History of.--The Fairbanks of Vermont, 1831.--Platform and other Scales.--Spring Weighing.--Automatic Recorders of Weight and Prices.--Testing Machines, English, German, American.--The Emery Scales.--Gages, Dynamometers.--Hydraulic Testing.--Delicate Operations.--Strength of a Horse-hair and Great Steel Beam, Tested by Same Machine.--Effect on Public Works. 384