They measured the way that the Ships make by the help of a little Mill, which was fastned to the Ship, and which turned by the resistance that its VVings found in the VVater when the Ship went forward and the Axle-tree of this Mill had a little Rong or Tooth, which every round pushed forwards one of the Teeth of the great VVheel, which turned another, and that another which turned a Pin or Handle, which marked the number of turnings, that the Mill made, by which means it was easie to take an account of the Perches, and Leagues that the Ship sailed. They made use of the same _Machine_ on the Land, fixing to the Nave of the VVheel of a Coach, a Tooth which made many VVheels be turned as in the above-mentioned _Machine_, at the last of which, was fastned a Pin or Handle, which marked the number of Perches and Leagues. This _Machine_ had likewise a sort of a Counting VVheel, which at every Mile that the Coach went, let a Pibble fall into a Vessel of Brass, to give notice that they had gone a Mile. ART. VII. _Of Machines of War_. [Sidenote: _Lib. 10. Chap. 15._] The _Machines_ of VVar of the Ancients were of three Sorts, for they were made either to Lance, Arrows, such as were the _Scorpions_ or _Javelins_, such as were the _Catapulta's_, or Stones, such as were _Ballista's_ or fiery Darts, such as were the _Pyroboli_, or they were made to beat down the VValls, such as were the battering Rams, and the _Terebra_, or to come covered to the VValls, and so safely Mount the Ramparts, such as were the _Tortoises_ or _Testudo's_, and the Towers of VVood. [Sidenote: _Lib. 10. Chap. 18._] The _Scorpions_ were a sort of great Crossbows, which were made use of to defend the VValls, and which likewise the Assailants made use of in the wooden Towers, to annoy those that defended the VValls. The _Catapulta_, lanced Javelins or Javelots, from 12 to 15 Foot in length, they were made of two Trees, set one against another, like the Masts of a Ship, which were bended in drawing them with a Hand-Mill. These Trees being on a suddain unbent, furiously struck together, and forced violently the Javelin. They were bent the one after the other by the same Cord, which was made of Guts, to the end, that the Master who managed the Engine, might be assured, that the two Trees or Beams were equally bent. He knew it by sounding the Cord when both the Beams were bent, and when the End above was drawn even to the Capital of the _Machine_, where they were stayed by a Pin of Iron, which was driven out by a quick stroke of a Hammer when they unbent it. There was a Cylinder which traversed an excentrical piece, by the help of which they heightned, or let down the End of one of the Beams below, according as the Master of the _Machine_ judged it necessary, for the augmenting or diminishing their bent, which was known by the sound of the Cord, which was alike in both, when they were equally bent. See Table XI.