Modes of measuring Time among the Ancients.--The Gnomon.--The Water-Clock.--The Hour-Glass.--The Water-Clock, improved by the Persians and by the Italians.--Gerbert invents the Escapement and the moving Weights.--The Striking-bell.--Maistre Jehan des Orloges.--Jacquemart of Dijon.--The first Clock in Paris.--Earliest portable Timepiece.--Invention of the spiral Spring.--First appearance of Watches.--The Watches, or “Eggs,” of Nuremberg.--Invention of the Fusee.--Corporation of Clockmakers.--Noted Clocks at Jena, Strasburg, Lyons, &c.--Charles-Quint and Jannellus.--The Pendulum. Among the ancients there were three instruments for measuring time--the _gnomon_, or sun-dial, which is only, as we know, a table whereon lines are so arranged as successively to meet the shadow cast by a gnomon,[20] thus indicating the hour of the day according to the height or inclination of the sun; the water-clock (_clepsydra_), which had for its principle the measured percolation of a certain quantity of water; and the hour-glass, wherein the liquid is exchanged for sand. It would be difficult to determine which of these three chronometric modes can lay claim to priority. There is this to be said that, according to the Bible, in the eighth century before Christ, Ahaz, King of Judah, caused a sun-dial to be constructed at Jerusalem; again, Herodotus says Anaximander introduced the sun-dial into Greece, whence it passed on to the other parts of the then civilised world; and that, in the year 293 before our era, the celebrated Papirius Cursor, to the astonishment of his fellow-citizens, had a sun-dial traced near the temple of Jupiter Quirinus. According to the description given by Athena (Athenæus?), the water-clock was formed of an earthenware or metal vessel filled with water, and then suspended over a reservoir whereon lines were marked indicating the hours, as the water which escaped drop by drop from the upper vessel came to the level. We find this instrument employed by most ancient nations, and in many countries it remained in use until the tenth century of the Christian era. [Illustration: Fig. 143.--The Clockmaker. Designed and Engraved by J. Amman.]