(The architect being at that time also the contractor.) The chapters are -- (1) on various machines, such as scaling-ladders, windmills, &c.; (2) on windlasses, axles, pulleys and cranes for moving heavy weights, such as those used by Chersiphron in building the great temple of Diana at Ephesus, and on the discovery by a shepherd of a quarry of marble required to build the same temple; (3) on dynamics; (4) on machines for drawing water; (5) on wheels for irrigation worked by a river; (6) on raising water by a revolving spiral tube; (7) on the machine of Ctesibius for raising water to a height; (8) on a very complicated water engine, the description of which is not intelligible, though Vitruvius remarks that he has tried to make the matter clear; (9) on machines with wheels to register the distance travelled, either by land or water; (10) on the construction of scorpiones for hurling stones; (11) and (12) on balistae and catapults; (13) on battering rams and other machines for the attack of a fortress; (14) on shields (testudines) to enable soldiers to fill up the enemy's ditches; (15) on other kinds of testudines; (16) on machines for defence, and examples of their use in ancient times.