=B.C. 200.=--Polybius, a Greek statesman and historian, describes (lib. x. cap. 45, “General History”) his optical telegraph--_pyrsia_--because the signals were invariably produced by means of fire-lights--an unquestionable improvement upon the modes of communication which had been previously suggested by Cleoxenes and Democritus. It consisted of a board upon which the twenty-four letters of the Greek alphabet were arranged in five columns, one space being vacant. The party signalling would hold up with his left hand a number of torches indicating the column from which the desired letter was to be taken, while in the right hand he would hold up to view as many torches as were necessary to designate the particular letter required. REFERENCES.--Rollin’s “Ancient History, 9th Dundee,” Vol VI. p. 321; “Emporium of Arts and Sciences,” Vol. I. pp. 296–299; “Penny Encycl.,” Vol. XXIV. p. 145. A good cut of the Polybius telegraph will be found at p. 2 of “Wireless Telegraphy,” by Wm. Maver, Jr., New York, 1904, and a very detailed account of all known fire signals is given at pp. 148 and 373, Vol. IV of “The History of Herodotus,” by Geo. Rawlinson, London, 1880. =B.C. 60–56.=--Lucretius (Titus Lucretius Carus), Roman poet, alludes to the magnet in his poem “De Rerum Natura” (“The Nature of Things”), thus translated by Dr. Thomas Busby, London, 1813, Book VI. vv. 1045–1059: “Now, chief of all, the Magnet’s powers I sing, And from what laws the attractive functions spring. (The Magnet’s name the observing Grecians drew From the Magnet’s region where it grew.) Its viewless, potent, virtues men surprise; Its strange effects they view with wondering eyes, When without aid of hinges, links or springs, A pendent chain we hold of steely rings, Dropt from the stone; the stone the binding source, Ring cleaves to ring, and owns magnetic force; Those held superior those below maintain; Circle ’neath circle downward draws in vain, While free in air disports the oscillating chain. So strong the Magnet’s virtue as it darts From ring to ring and knits the attracted parts.” A rendering by Thomas Creech, A.M., London, 1714, Book VI. vv. 894–989, likewise deserves reproduction here: “Now sing my muse, for ’tis a weighty cause. Explain the Magnet, why it strongly draws, And brings rough Iron to its fond embrace. This, Men admire; for they have often seen Small Rings of Iron, six, or eight, or ten, Compose a subtile chain, no Tye between; But, held by this, they seem to hang in air, One to another sticks and wantons there; So great the Loadstone’s force, so strong to bear! * * * * *