NOTE.
The telegraph, though not generally used in Europe till the commencement of the French revolution, appears to have been well known to the ancients. Polybius describes a method of communication, which was invented by Cleoxenus, which answered both by day and night. Kircher and Scott likewise allude to its use; but the description given by the Marquis is evidently superior to any that had preceded him; and, indeed, must have nearly resembled that in use at the present period.
No. VII.
A way to do it by night as well as by day, though as dark as pitch is black.
NOTE.
The allusion here to a telegraphic communication is likewise sufficiently evident; though it is obvious that, for night signals, it will become necessary to substitute rockets or reflecting lamps for the painted boards.
Among the signs for nightly information at a distance, those by fire are extremely common, and have been used by the Chinese, Persians, and other nations, in the remotest times. This species of communication is affirmed by Diodorus Siculus to have been practised by Medea in her conspiracy with Jason, which carries us back three thousand and seventy years; and although there must be some uncertainty on this question, Pliny, in his "History," lib. vii. cap. 56, says, it originated with Sinon. "Specularem significationem Trojano bello Sinon invenit." This was the signal upon which Sinon agreed to unlock the wooden horse in the siege of Troy, about 1184 years before Christ:
"——Flammas cum regia puppis
Extulerat."Virgil. Æn. lib. ii. 256.
And, after the taking of Troy, Æschylus relates, that Agamemnon immediately apprized his queen, Clytemnestra, of that event by a similar method; which, we suppose, must have been done either by men placed at certain distances with lighted torches, which they held up in succession, or by a considerable number of fires on the tops of hills, denoting the simple fact previously agreed on between the parties. See Onosander's Strategicus, cap. 25, where this practice is described.
The fire-signals of the Greeks and Romans are also slightly mentioned by Quintus Curtius, Livy, Cæsar, Herodotus, Homer, and Thucydides; likewise by Vegetius and Frontinus; but still more in detail by Polybius and Æneas Tacticus; the latter of whom was contemporary with Aristotle, and has left a valuable fragment on the duties of a general, (translated into Latin by Casaubon,) wherein are many curious remarks on the subject of secret correspondence. The Greek signals were much improved by Polybius, who, in his history, (lib. x. cap. 45. p. 296. tom. iii. Lips. 1790. edit. Joh. Schweighaeuser,) attributes the invention to Cleomenes and Democritus, or (more correctly) to Cleoxenus and Democlitus, in words thus rendered: "Postrema ratio, cujus auctores sunt Cleoxenus et Democlitus, sed quam nos correximus, certa definitaque est, adeo ut quidquid exortum fuerit negotii, id possis certo facere notum." Prior to that period, the information communicated by torches, flags, smoke, or otherwise, was very limited, and it was requisite to settle beforehand what each signal should mean; whereas Polybius showed how to correspond alphabetically, and to give or receive any species of intelligence, without this previous concert. The plans of Æneas Tacticus had never arrived at such perfection, and were therefore of comparatively small use; though, without doubt, he at least equalled any of his predecessors in the facility of his telegraphic communications.
No. VIII.
A way how to level and shoot cannon by night as well as by day, and as directly, without a platform or measures taken by day, yet by a plain and infallible rule.