The _Ballista's_ were bended and strung as the _Catapulta's_, but instead of Javelins, they cast great Stones. [Sidenote: _Lib._ 10. _Chap._ 22.] The _Pyroboli_ were _Machines_, which lanced or cast Darts, to vvhich vvas fixed combustible Matter, vvhich vvas kindled vvhen they darted it against _Machines_ of VVar or Shipping. The Ram vvas to beat dovvn Walls and make breaches. It vvas a great Beam headed with Iron; it vvas hung by the middle, and pushed by the Soldiery vvith great violence against the Walls. The _Terebra_ vvas something like the Ram, being a strong Beam pointed vvith Iron, but it vvas sharp pointed, and it made vvay for the Ram, splitting the Stones. [Sidenote: _Lib. 10. Chap. 20._] The _Testudo_ or _Tortoise_, vvere great large and low Towers of Wood, which were rowled upon six or eight Wheels, they were covered with raw Hides to defend them from fire. Their use was to cover them that approached the Walls to undermine them, or beat them with the battering Ram. The Towers of Wood were made to raise the Assailants as high as the Walls, to chace the Besieged away with Arrows and Scorpions, and to lay Bridges from the Towers to the Wall; they were sometimes Thirty Fathoms high, having Twenty Stages. They were covered, as the _Tortoises_ with raw Hides; they had each of them a Hundred Men, which were employed as well to move them, as to annoy the Besieged. _FINIS._ ADVERTISEMENT. _The Figures inserted here are those only which are chiefly necessary to the understanding of_ Vitruvius, _that is to say, those which serve for the comprehending the Rules that Architecture gives for Buildings, now in use. The Figures of other things, of which_ Vitruvius _treats, are omitted, it being enough to give One only, to serve as an Example of each kind_, viz. _one for all Temples, one for all Theatres, and one for all Machines._ THE EXPLICATION Of the FIRST TABLE. This Table contains the seven several sorts of Masonry; A is the first, which was called _Reticulatum_, because it was like the Mashes of Nets; BB is the second, it's called _Insertum_, that is to say, _bound Masonry_, because the Stones are one bound within another, every one being bound with four, two below, and two above: CC is the third sort, which was particular to the _Greeks_; it may be called double binding, for it's not only of Stones of the same course, but of two courses III. D is the fourth, called _Isodomum_, because the Beds or Lays are equal in height. E is the fifth, called _Pseudisodomum_, because they are of an equal heighth. FF, GG, H is the sixth, called _Emplecton_, because it was filled up any way in the middle. FF are the Stones which make the Courses. K is the seventh, which may be called _Compound_, because its Courses are of hewn Stone, and the middle filled up with Rubbish; and these Courses are fasten'd together with Cramp-irons. This Table refers to _pag._ 47. [Illustration: _Plate I._] THE EXPLICATION Of the SECOND TABLE.