The Ten Books on Architecture Part 29

7. Likewise, the projecting end of the ram had a box framed and constructed of boards, in which was stretched a 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 one hundred feet, and likewise in its thrust it covered a s.p.a.ce from right to left of not less than one hundred feet.

One hundred men controlled it, though it had a weight of four thousand talents, which is four hundred and eighty thousand pounds.

CHAPTER XVI

MEASURES OF DEFENCE

1. With regard to scorpiones, 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, on another against cautious men, and on still another against the cowardly.

2. And so, if any 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 circ.u.mstances or the situations demand. With regard to works of defence, it is not necessary to write, since the enemy do not construct their defences 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 is said to have been the experience of the Rhodians.

3. For Diognetus was a Rhodian architect, to whom, as an honour, was granted out of the public treasury a fixed annual payment commensurate with the dignity of his art. At this time an architect from Aradus, Callias 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 helepolis as it approached the fortifications, and brought it inside the wall. The Rhodians, when they had seen this model, filled with admiration, took from Diognetus the yearly grant and transferred this honour to Callias.

4. Meanwhile, king Demetrius, who because of his stubborn courage was called Poliorcetes, making war on Rhodes, brought with him a famous Athenian architect named Epimachus. He constructed at enormous expense, with the utmost care and exertion, an helepolis one hundred and thirty-five feet high and sixty feet broad. He strengthened it with hair and rawhide so that it could withstand the blow of a stone weighing three hundred and sixty pounds shot from a ballista; the machine itself weighed three hundred and sixty thousand pounds. When Callias was asked by the Rhodians to construct a machine to resist this helepolis, 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 Rhodians, in the same manner, deceived by the same reasoning, inflicted injury and insult on Diognetus. 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 Diognetus, 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 both 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 helepolis moving up, before it could reach the wall, came to a 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 Diognetus, withdrew with his fleet.

8. Then the Rhodians, freed from the war by the cunning of Diognetus, thanked him publicly, and decorated him with all honours and distinctions. Diognetus brought that helepolis into the city, set it up in a public place, and put on it an inscription: "Diognetus out of the spoils of the enemy dedicated this gift to the people." Therefore, in works of defence, not merely machines, but, most of all, wise plans must be prepared.

9. Likewise at Chios, when the enemy had prepared storming bridges on their s.h.i.+ps, the Chians, 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 s.h.i.+ps grounded on the mound beneath the water, and could not approach the wall nor withdraw, but pierced with fire-darts were burned there. Again, when Apollonia was being besieged, and the enemy were 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 defence, 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 Trypho, the Alexandrine architect, was there. He planned a number of countermines inside the wall, 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 a mine of the enemy, began to ring from the strokes of their iron tools. So from this it was ascertained where the enemy, pus.h.i.+ng 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 Ma.r.s.eilles was being besieged, and they were pus.h.i.+ng forward more than thirty mines, the people of Ma.r.s.eilles, 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 pa.s.sages of the mine were suddenly opened, the immense ma.s.s of water let in undermined the supports, and all who were within were overpowered by the ma.s.s of water and the caving in of the mine.

12. Again, when a rampart was being prepared against the wall in front of them, and the place was heaped up with felled trees and works placed there, by shooting at it with the ballistae 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 raised the head of the ram, they did not allow the wall to be touched, and finally they destroyed the entire machine by glowing fire-darts and the blows of ballistae. 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

SCAMILLI IMPARES (BOOK III, ch. 4)

No pa.s.sage in Vitruvius has given rise to so much discussion or been the subject of such various interpretations as this phrase.

The most reasonable explanation of its meaning seems to be that of emile Burnouf, at one time Director of the French School at Athens, published in the _Revue Generale del' Architecture_ for 1875, as a note to a brief article of his on the explanation of the curves of Greek Doric buildings. This explanation was accepted by Professor Morgan, who called my attention to it in a note dated December 12, 1905. It has also quite recently been adopted by Professor Goodyear in his interesting book on _Greek Refinements_.

Burnouf would translate it _nivelettes inegales_, "unequal levellers." He states that in many parts of France in setting a long course of cut stone the masons make use of a simple device consisting of three pointed blocks of equal height used as levellers, of which two are placed one at each extremity of the course, while the third is used to level the stones, as they are successively set in place, by setting it upon the stone to be set and sighting across the other two levellers. If two "levellers" of equal height are used with a third of less height placed at the centre of the course, with perhaps others of intermediate height used at intermediate points, it would obviously be equally easy to set out a curved course, as, for instance, the curved stylobate of the Parthenon which rises about three inches in its length of one hundred feet. By a simple calculation any desired curve could be laid out in this way. The word scamillus is a diminutive of _scamnum_, a mounting-block or bench.

Practically the same explanation is given by G. Georges in a memoir submitted to the Sorbonne in April, 1875. Georges adds an interesting list, by no means complete, of the various explanations that have been offered at different times.

Philander (1522-1552). Projections of the stylobate or pedestals.

Barbaro (1556-1690). The same.

Bertano (1558). Swellings of the die of the stylobate or bosses in the stylobate or the frieze of the entablature.

Baldus (1612). Sub-plinths placed under the bases of the columns.

Perrault (1673-1684). Projection of the stylobate.

Polleni (1739). The same.

Galiani (1758-1790). Projection of the stylobate with hypothesis of embossments on the stylobates and the bases of the columns.

Tardieu and Coussin (1837) and Mauffras (1847). Projection of the stylobates.

Aures (1865). Steps or offsets between the stylobate and the columns.

The list of Georges is wholly French and Italian.

Fra Giocondo's interpretation is indicated in our reproduction of the ill.u.s.tration in his edition of 1511.

Hoffer (1838) and afterwards Pennethorne (1846) and Penrose (1851) gave measurements showing the curvatures in the Parthenon and the temple of Theseus in Athens. Penrose and most writers who followed him supposed the "scamilli impares" to be projections or offsets on the stylobate required on account of the curves to bring the column into relation with the architraves above, and similar offsets of unequal or sloping form were supposed to be required above the abaci of the capitals, but such offsets, although sometimes existing, have no obvious connection with the pa.s.sage in Vitruvius.

C. Botticher (1863) and more recently Durm have denied the original intention of the curves and ascribe them to settlement, a supposition which hardly accords with the observed facts. Reber, in the note on this pa.s.sage in his translation of Vitruvius (1865), thinks the scamilli were sloping offsets on the stylobate to cause the inclination of the columns, but admits that nothing of the kind has been found in the remains so far examined. It may be added that this is at variance with the statement of the purpose of the scamilli which Vitruvius gives.

a.s.suming, as I think we must, that the horizontal curvature of the stylobate in such buildings as the Parthenon was intended and carefully planned, Burnouf's explanation fits the case precisely and makes this pa.s.sage of Vitruvius straightforward and simple.

This can be said of no other explanation, for all the others leave the pa.s.sage obscure and more or less nonsensical. Durm's attempt to refer the pa.s.sage to the case of the temple with a podium which has just been spoken of by Vitruvius is somewhat forced, or at least unnecessary. Clearly the pa.s.sage refers to stylobates in general; but Reber also so translates and punctuates as to make the use of the "scamilli impares" refer only to the case of temples built in the Roman manner with the podium. His resulting explanation still leaves the pa.s.sage obscure and unsatisfactory. One may finally refer to the ingenious but improbable explanation of Choisy, who translates it echelons impairs, and explains them as offsets arranged according to the odd numbers, _nombres impairs_, i. e., offsets varying at equal intervals in the proportion of 1, 3, 5, 7, 9, etc., and which he claims was applied also to the entasis of columns.

H. L. WARREN.