Chapter V. Of Wooden Bridges, and of the advertencies which ought to be had in the building of them

BRIDGES are made of wood, either upon one occasion only, like those which are made for all those accidents that usually happen in war; of ‘which sort that is the most celebrated which Julius Cesar directed over the Rhine; or secondly, that they may perpefully serve for the conveniency of every body. After this manner we read that Hercules built the first bridge that ever was made, over the Tiber, in the place where Rome was afterwards built; when, after having killed Geryon, he vidtorioufly led his herd through Itah. It was called the holy bridge, and was situated in that part of the Tiber, where towards the Pons Sublicius was built by Ancus Martius the Ring, which was likewise all of timber, and its beams were joined together with so much art, that one could take them away, and replace them according as necessity should require, there being neither nails nor any iron whatsoever in it. How it was constructed is not known; but by what writers say of it, that it was made upon great pieces of timber, which supported others, from which it took the name of Swblicius; because such timbers in the Yolfeian tongue were called Sublices.

This was the bridge that was defended by Horatius Cares, with so much advantage to his native country, and glory to himself. This bridge was near Ripa, where there are fll vejhgia to be seen in the middle of the river, because it was afterwards made of stone by Amirlrus EPI°US the praetor, and restored by the Emperor Tiberius, and by ANTONINUS Pius.

Wooden bridges of this kind ought to be made in such a manner, that they may be very strong, and so tied together by large strong timbers, that there may not be any danger of their breaking, either thro’ the great multitude of people, and of animals, or by the weight of the carriages and of the artillery that shall pals over them, nor liable to be ruined by the inundations and the floods in rivers. Those that are made at the gates of the cities, however, which we call draw-bridges, because they may be raised and let fall according to the will of those within, are usually paved, or covered with bars or plates of iron, that they may not be spoiled or broken by the wheels of carriages, and by the feet of cattle.

The timbers, as well those which are fixed in the water, as those that form the length and breadth of the bridge, ought to be long and thick, according as the depth, the breadth, and the velocity of the river shall require,

But because the particulars are infinite, one cannot give a certain and determinate rule for them. Wherefore I shall give some designs, and hall mention their measures, from which every one may easily be able, according as occasion shall offer, of exercising the acuteness of his understanding, to take his measures and form 2 work that is worthy of praise.