Beacon denotes any signal set upon a height, but especially the alarm-fires at one time used to spread the intelligence of foreign invasion or other great event. These fire-signals were in use in the earliest times, and notices of them are found in the literary remains of ancient Persia, Palestine, and Greece. They were made by kindling a pile of wood on the tops of lofty mountains, and keeping the flame bright by night, or having the fire so covered as to emit a dense smoke by day. There were various preconceived modes of exhibiting the light or smoke, so as to indicate the nature of the intelligence. Thus, an act of the parliament of Scotland in 1455 directs that one bale on fire shall be warning of the approach of the English in any manner; two bales blazing beside each other, that they are coming indeed; and four bales, that they are coming in great force. Bale is akin to the Sansk. bhalas, 'lustre'; beacon is a word of doubtful etymology, not found beyond the Teutonic languages.
An early instance of beacon-signals is found in the book of the prophet Jeremiah, in his call, in chap. vi. 1, to the people of Benjamin to kindle a fire-signal on one of their mountains: 'Set up a sign of fire in Beth-hacerem; for evil appeareth out of the north, and great destruction.' Another ancient instance of the use of a line of beacons occurs in the Agamemnon of Æschylus. The Greek commander is represented as communicating the intelligence of the fall of Troy to his queen, Clytemnestra, at Mycenæ, in the Peloponnesus. The line consists of eight mountains, and the news is supposed to be conveyed in one night from Troy.
In England the beacons were kept up by a rate levied on the counties, and had watches regularly stationed at them, and horsemen to spread the intelligence during the day, when the beacons could not be seen. They were carefully organised when the Spanish Armada was looked for. In 1856 an old beacon-work on Malvern Hill, which had done its part in former days in spreading the intelligence of the appearance of the Armada, of the Dutch fleet, and of the Young Cavalier, was lighted up in anticipation of the close of the Crimean war, and afforded an interesting amusement to scientific persons in estimating the distance at which the blaze could be seen from distant hills. Again, on the night of 21st June 1887, a multitude of jubilee beacons, throughout the length of the kingdom, received their signal from Malvern Hill, the time taken for its transmission thence to the Lake country being seven minutes.