s; and the other Roman wall which united the Forth and Clyde, 36 miles.
The Egyptians built no permanent bridges across the Nile, but were familiar with framing trestlework, and with ponton and draw bridges; the latter are seen frequently in their paintings representing fortified towns, sieges, etc.
The Greeks had but small rivers, and had no stone bridges until after the Roman conquest.
We learn from the Greek historians that bridges were constructed by Cyrus (536 B. C.), Darius (490 B. C.), Xerxes (480 B. C.), and Pyrrhus (280 B. C.). Each of these was a military bridge for a special purpose, and had no permanent character.
The bridge of Cyrus, over the Meander, was supported on boats, like those which crossed the Bosphorus and the Hellespont under the orders of his successors; Xenophon states that the bridge of Cyrus had seven boats.
The bridge of Xerxes was 500 paces in length.
Ships were used as pontons; cords of flax and biblos united them; transverse beams were la
ss-sections of a ship.
When the middle of the ship has a portion of a uniform cross-section, such is called the midship-body.
The frame at the midship or largest section of a vessel.
A bridge, usually of a temporary character, designed for the passage of an army with its artillery and supplies or for maintaining its communications.
Probably the earliest on record is that thrown by Darius across the Bosphorus during his invasion of Greece, 490 B. C.
Ten years later, his successor, Xerxes, crossed his army, said to have been 1,700,000 strong, from Asia into Europe by similar means.
The bridge of Xerxes across the Hellespont consisted of ropes resting on galleys and supporting planks.
The account given by Herodotus may be thus briefed: —
Two parallel bridges were constructed, one supported by 360 vessels and the other by 314.
The vessels are classed as triremes and penteconters, and were anchored parallel, the prows facing up<
alternately depressed by the feet and raised by the spring-poles.
Each skin cover has a hole in the middle, which is stopped by the heel as the weight of the person is thrown upon it, and is left open by withdrawal of the foot as the cover is raised.
Variously modified in detail and increased in size, these simple furnaces are to be found in several parts of Europe, the Catalan and Swedish furnaces resembling in all probability those of the Chalybes, so famous in the time of Marathon (490 B. C.), and those of the fabrica or military forge established in England by Hadrian (A. D. 120) at Bath, in the vicinity of iron ore and wood.
The brave islanders met their Roman invaders with scythes, swords, and spears of iron, and the export of that metal from thence shortly afterward is mentioned by Strabo.
During the Roman occupation of England some of the richest beds of iron ore were worked, and the debris and cinders yet exist to testify to two facts, — one, that the amount of mater