 Book 10, chapter 14-16 of Ten Books on Architecture. This LibriVox recording is in the public domain, recording by Fredrik Carlson. Ten Books on Architecture by Vitruvius, translated by Morris Hickey Morgan. Chapter 14, The Tortoise. 1. A tortoise intended for the filling of ditches, and thereby to make it possible to reach the wall, is to be made as follows. Let a base, termed in Greek eskara, be constructed, with each of its side 21 feet long and with four crosspieces. Let these be held together by two others, two-third of a foot thick and half a foot broad. Let the crosspieces be about three feet and a half apart, and beneath and in the spaces between them set the trees, termed in Greek hamaxopodus, in which the axles of the wheels turn in iron hoops. Let the trees be provided with pivots and also with holes through which the levers are passed to make them turn, so that the tortoise can move forward or back or towards its right or left side, or if necessary obliquely, all by the turning of the trees. 2. Let two beams be laid on the base, projecting for six feet on each side, round the projections of which let two other beams be nailed, projecting seven feet beyond the former and of the thickness and breadth prescribed in the case of the base. On this framework set up posts mortised into it, nine feet high exclusive of their tenons, one foot and a quarter square and one foot and a half apart. Let the posts be tied together at the top by mortised beams. Over the beams let the rafters be set, tied one into another by means of tenons, and carried up 12 feet high. Over the rafters set the square beam by which the rafters are bound together. 3. Let the rafters themselves be held together by bridgings and covered with boards, preferably of Holm oak, or this failing of any other material which has the greatest strength, except pine or older. For these woods are weak and easily catch fire. Over the boardings let there be placed waddles very closely woven of thin twigs as fresh as possible. Let the entire machine be covered with raw hide, soot together, doubled and soft with seaweed or straw soaked in vinegar. This way the blows of ballista and the force of fires will be repelled by them. Chapter 15 Hegitor's Tortoise 1. There is also another kind of tortoise which has all the other details as described above except rafters, but it has rounded our parapet and battlements of boards and eaves sloping downwards, and is covered with boards and hides firmly fastened in place. Above this let clay kneaded with hair be spread to such a thickness that fire can it injure the machine. These machines can, if need be, have eight wheels should it be necessary to modify them with reference to the nature of the ground. Tortoises, however, which are intended for excavating, termed in Greek, or ryktides, have all the other details as described above, but their fronts are constructed like the angles of triangles, in order that when missiles are shot against them from a wall they may receive the blows not squarely in front, but glancing from the sides, and those excavating within may be protected without danger. 2. It does not seem to be out of place to set forth the principles of which Hegitora Byzantium constructed a tortoise. The length of its base was 63 feet, the breadth 42. The corner posts, four in number, which were set upon this framework, were made of two timbers each, and were 36 feet high, a foot and a quarter thick, and a foot and a half broad. The base had eight wheels by means of which it is moved about. The height of these wheels were six and three quarters feet, their thickness three feet, thus constructed of three pieces of wood, united by alternate opposite dovetails, and bowed together by cold drawn iron plates, they revolved in the trees or a maxi poles. 3. Likewise on the plane of the crossbeams above the base were erected posts 18 feet high, three quarters of a foot broad, two-thirds of a foot thick, and a foot and three quarters apart. Above these framed beams, a foot broad, and three quarters of a foot thick held the whole structure together. Above this the rafters were raised with an elevation of 12 feet. A beam set above the rafters united their joinings. They also had bridging, fast and transversely, and a flooring laid on them protected the parts beneath. 4. It had moreover a middle flooring on girts, where scorpions and catapults were placed. There were set up also two framed uprights four to five feet long, a foot and a half in thickness, and three quarters of a foot in breadth, joined at the tops by a mortised crossbeams, and by another halfway up mortised into the two shafts and tied in place by iron plates. Above this was set between the shafts and the crossbeams, a block pierced on either side by sockets and firmly fastened in place with clamps. In this block were two axles turned on a lathe, and ropes fastened from them held the ram. 5. Over the head of these ropes which held the ram was placed a parapet fitted out like a small tower so that, without danger, two soldiers standing in safety could look out and report what the enemy were attempting. The entire ram had a length of 180 feet, a breadth at the base of a foot and a quarter, and a thickness of a foot, tapering at the head to a breadth of a foot and a thickness of three quarters of a foot. 6. This ram, moreover, had a beak of hard iron such as ships of war usually have, and from the beak iron plates four in number about 15 feet long were fastened to the wood. From the head to the very heel of the beam were stretched cables, three in number and eight digits thick, fastened just as in a ship from stem to stern continuously, and three cables were bound with cross girdles, a foot and a quarter apart. Over these the whole ram was wrapped with raw hide. The ends of the ropes from which the ram hung were made of fourfold chains of iron, and these chains were themselves wrapped in raw hide. 7. Likewise, the projecting end of the ram had a box framed and constructed of boards in which was stretched and net made of rather large ropes over the rough surfaces of which one easily reached the wall without the feet slipping, and this machine moved in six directions, forward and backward, also to the right or left, and likewise it was elevated by extending it upwards and depressed by inclining it downwards. The machine could be elevated to a height sufficient to throw down a wall of about 100 feet, and likewise in its thrust it covered a space from right to left of not less than 100 feet. 100 men controlled it, though it had a weight of 4,000 talents, which is 480,000 pounds. 16. Measures of Defense 1. With regard to scorpions, catapults and ballistae, likewise with regard to tortoises and towers, I have set forth, as seemed to me especially appropriate, both by whom they were invented and in what manner they should be constructed, but I have not considered it as necessary to describe ladders, cranes and other things, the principles of which are simpler, for the soldiers usually construct these by themselves, nor can these very machines be useful in all places nor in the same way, since fortifications differ from each other and so also the bravery of nations. For siege works against bold and venturesome men should be constructed on one plan and on another against cautious men and on still another against the cowardly. 2. And so if one pays attention to these directions and by selection adapts their various principles to a single structure, he will not be in need of further aids, but will be able, without hesitation, to design such machines as the circumstances or the situations demand. With regard to worser defense, it is not necessary to write, since the enemy do not construct their defenses in conformity with our books, but their contrivances are frequently foiled on the spur of the moment by some shrewd, hastily conceived plan without the aid of machines, as it said have been the experience of the Rodians. 3. For Diagnetus was a Rodian architect, to whom, as an honor, was granted out of their public treasury a fixed annual payment commensurate with the dignity of his art. At this time an architect from Aridus, Callius by name, coming to Rhodes, gave a public lecture and showed a model of a wall over which he set a machine on a revolving crane with which he seized an helopolis, as it approached the fortifications and brought it inside the wall. The Rodians, when they had seen this model, filled with admiration, took from Diagnetus the yearly grant and transferred this honor to Callius. 4. Meanwhile, King Demetius, who because of his stubborn courage was called Polyorcetus, making war on Rhodes, brought with him a famous Athenian architect named Epimachus. He constructed at enormous expense, with utmost care and exertion, an helipolis 135 feet high and 60 feet broad. He strengthened it with hair and raw hides so that it could withstand the blow of a stone weighing 360 pounds shot from a ballista. The machine itself weighed 360,000 pounds. When Callius was asked by the Rodians to construct a machine to resist this helopolis, and to bring it within the wall as he had promised, he said that it was impossible. 5. For not all things are practicable on identical principles, but there are some things which when enlarged in imitation of small models are effective, others cannot have models but are constructed independently of them, while there are some which appear feasible in models, but when they have begun to increase in size are impracticable, as we can observe in the following instance. A half inch, inch, or inch-and-a-half hole is bored with an auger, but if we should wish in the same manner to bore a hole a quarter of a foot in breadth, it is impracticable, while one of half a foot or more seems not even conceivable. 6. So too in some models it is seen how they appear practicable on the smallest scale and likewise on a larger, and so the Rodians in the same manner, deceived by the same reasoning, inflicted injury and insult on Diognities. Therefore, when they saw the enemy stubbornly hostile, slavery threatening them because of the machine which had been built to take the city, and that they must look forward to the destruction of their state, they fell at the feet of Diognities, begging him to come to the aid of the Fatherland. He at first refused. 7. But after free-born maidens and young men came with the priests to implore him, he promised to do it on condition that if he took the machine, it should be his property. When these terms had been agreed upon, he pierced the wall in the place where the machine was going to approach it, and ordered all to bring forth from public and private sources all the water, excrement and filth, and to pour it in front of the wall through pipes projecting through this opening. After a great amount of water, filth and excrement had been poured out during the night, on the next day the helipolis moving up, before it could reach the wall, came to stop in the swamp made by the moisture, and could not be moved forwards, nor later even backwards. And so Demetrius, when he saw that he had been baffled by the wisdom of Diognities, withdrew with his fleet. 8. Then the Rhodians, freed from the war by the cunning of Diognities, thanked him publicly, and decorated him with all honors and distinctions. Diognities brought that helipolis into the city, set it up in a public place, and put on it an inscription. Diognities, out of the spoils of the enemy, dedicated this gift to the people. Therefore, in works of defense, not merely machines, but most of all, wise plans must be prepared. 9. Likewise at Caels, when the enemy had prepared storming bridges on their ships, the Caians, by night, carried out earth, sand and stones, into the sea before their walls. So, when the enemy on the next day tried to approach the walls, their ships grounded on the mound beneath the water, and could not approach the wall, nor withdraw, but pierced with fire-dars were burned there. Again, when Apollonia was again besieged, and the enemy was thinking by digging mines to make their way within the walls without exciting suspicion, and this was reported by scouts to the people of Apollonia, they were much disturbed and alarmed by the news, and having no plans for defense, they lost courage, because they could not learn either the time or the definite place where the enemy would come out. 10. But at this time trifle, the Alexandrine architect was there. He planned a number of counter-reminds inside the walls, and extending them outside the wall beyond the range of arrows, hung up in all of them brazen vessels. The brazen vessels hanging in one of these mines, which was in front of the mine of the enemy, began to ring from the strokes of their iron tools. So, from this it was a certain weather enemy pushing their mines thought to enter. The line being thus found out, he prepared kettles of hot water, pitch, human excrement and sand heated to a glow. Then, at night, he pierced a number of holes and pouring the mixture suddenly through them, killed all the enemy who were engaged in this work. 11. In the same manner, when Marseille was being besieged and they were pushing forward more than 30 mines, the people of Marseille distrusting the entire moat in front of their wall lowered it by digging it deeper. Thus all the mines found their outlet in the moat. In places where the moat could not be dug, they constructed within the walls a basin of enormous length and breadth, like a fish pond, in front of the place where the mines were being pushed and filled it from wells and from the port. And so, when the passages of the mine were suddenly opened, the immense mass of water let in, undermined the supports, and all who were within were overpowered by the mass of water and the caving in of the mines. 12. Again, when a rampart was being prepared against the wall in front of them and the place where heaped up with fell trees and works placed there, by shooting at it with a ballastigh red hot iron bolts, they set the whole work on fire. And when a ram tortoise had approached to batter down the wall, they let down a noose. And when they had caught the ram with it, winding it over a drum by turning a capstan, having raced the head of the ram, they did not allow the wall to be touched, and finally they destroyed the entire machine by glowing fire-dots and the blows of ballastigh. Thus by such victory, not by machines, but in opposition to the principle of machines, has the freedom of states been preserved by the cunning of architects. Such principles of machines, as I could make clear, and as I thought most serviceable for times of peace and of war, I have explained in this book. In the nine earlier books, I have dealt with single topics and details, so that the entire work contains all the branches of architecture set forth in ten books. Finis. End of The Ten Books on Architecture by Marcus Vitruvius Polio, translated by Morris Hickey Morgan.