o have had three arches of stone.
Doubts have been suggested as to the authenticity of this account; but it is not surprising when we consider the Cloaca Maxima, constructed in the same reign.
The Romans appear to have been the first to construct arched bridges; several of which still exist in Syria and Palestine, and are the oldest stone-arch bridges in existence, unless some of the Etruscan and Chinese bridges antedate them.
The Pons Senatorius was erected across the Tiber by Caius Flavius Scipio, 127 B. C.
Julius Caesar's and Trajan's bridges.
A trestle-bridge on piles (a. Fig. 924) was built by Julius Caesar across the Rhine about 55 B. C. He left an account of its construction, but the authorities construct it differently from the specification extant.
It was founded upon piles driven into the bed of the river.
The piles were united by a beam, on which were laid joists in the direction of the length of the bridge.
Upon the joists were laid hurdles supporting the ro
n or plates made by hammering out old horseshoes.
Jefferson studied and wrote on the subject, to determine the proper shape of the mold-board.
He treated it as consisting of a lifting and an upsetting wedge, with an easy connecting curve.
Newbold of New Jersey, in 1797, patented a plow with a mold-board, share, and landside all cast together.
Peacock, in his patent of 1807, cast his plow in three pieces, the point of the colter entering a notch in the breast of the share.
Jethro Wood of Scipio, N Y., patented improvements in 1819, and made the best plows up to date.
He met with great opposition and then with much injustice, losing a competence in introducing his plow and fighting infringers.
The peculiar merit of his plow consisted in the mode of securing the cast-iron portions together by lugs and locking pieces, doing away with screw-bolts and much weight, complexity, and expense.
It was the first plow in which the parts most exposed to wear could be renewed in the field by t