were made on limestone, some of which were vitrified, but all of which were agglutinated; it is, however, suspected that some extraneous substance must have been intermixed. A globule produced from one of the specimens, on being put into the mouth, flew into a thousand pieces, occasioned, it is presumed, by the moisture.

[Pantologia.

CHAP. V.

GENERAL ARCHITECTURE AND MECHANICAL SCIENCES.

SECTION I.

Architecture and Mechanical Sciences of the Ancients.

A RCHIMEDES alone would afford sufficient matter for a volume, in giving a detail of the marvellous discoveries of a genius so profound, and fertile in invention. We have seen in the preceding chapters, that some of his discoveries appeared so much above the reach of men, that many of the learned of our days found it more easy to call them in doubt, than even to imagine the means whereby he had acquired them. We are again going to produce proofs of the fecundity of genius belonging to this cele. brated man; and in how high a degree of excellence he possessed this inventive faculty, may easily be judged of by the greatness of those events which were effected by it. Leibnitz, who was one of the greatest mathematicians of his age, did justice to the genius of Archimedes when he said, that if we were better acquainted with the admirable productions of that great man, we would throw away much less of our applause on the discoveries of eminent moderns.

Wallis also, in speaking of Archimedes, calls him a man of admirable sagacity, who laid the foundation of almost all those inventions, which our age glories in having brought to perfection. In reality, what a glorious light hath he diffused over the mathea matics, in his attempt to square the circle; and in discovering the square of the parabola, the properties of spiral lines, the proportion of the sphere to the cylinder, and the true principles of statics and hydrostatics? What a proof of his sagacity did he give in discovering the quantity of silver, that was mixed along with the gold, in the crown of King Hierem ; whilst he reasoned upon that principle, that all bodies immersed in water, lose just so much of their weight, as a quantity of water equal to them in bulk weighs ? Hence he drew this consequence, that gold being more compact, must lose less of its weight, and silver more; and that a mingled mass of both, must lose in proportion to the quantities mingled. Weighing therefore the crown in water and in air, and two masses, the one of gold, the other of silver, equal in weight to the crown; he thence determined what each lost of their weight, and so resolved the problem. He likewise invented a perpetual screw, valuable on account of its being capable to overcome any resistance; and the screw, that still goes by his own name, used in ele. vating of water. He, of himself alone, defended the city of Syracuse, by opposing to the efforts of a Roman general, the re. sources he found in his own genius. By means of many various warlike machines, all of his own construction, he rendered Syracuse inaccessible to the enemy. Sometimes he hurled upon their land-forces stones of such an enormous size, as crushed whole bodies of them at once, and put the whole army into confusion. And when they retired from the walls, he still found means to annoy them; for with catapults and balistæ, he overwhelmed them with arrows innumerable, and beams of a-prodigious weight. If their vessels approached the fort, he seized them by the prows with grapples of iron, which he let down upon them from the wall, and rearing them up in the air, to the great astonishment of every body, shook them with such violence, as either to break them in pieces, or sink them to the bottom. And when the Romans thought of sheltering themselves from his pursuit, by keeping at a distance from the haven, he borrowed fire from heaven, and aided by his own ingenuity, wrapped them in sudden and inevitable con. flagration, as we have seen in a preceding chapter.

The superior knowledge he had in sciences, and his confidence in the powers of mechanism, prompted him once to say to King Hieron, who was his patron, admirer and friend; give me but some other place to stand upon, and I'll set the earth itself in motion : and when the king, amazed at what he had said, seemed to be in hesitation: he gave him a striking proof of the possibility of what

he had advanced, by launching singly by himself a ship of a prodi. gious size. He built likewise for the king an immense galley, of twenty banks of oars, containing spacious apartments, gardens, walks, ponds, and all other conveniences suitable to the dignity of a great King. He constructed also a sphere, representing the motions of the stars, which Cicero esteemed one of the inventions which did the highest honour to human genius. He perfected the manner of augmenting the mechanic powers by the multiplication of wheels and pullies; and, in short, carried mechanics so far, that the works he produced of this kind, even surpass imagination.

Nor was Archimedes the only one who succeeded in mechanics. The immense machines, and of such astonishing force, as were those which the art of the ancients adapted to the purposes of war, are a proof they came nothing behind us in this respect. It is with difficulty we can conceive how they reared those bulky moving towers, an hundred and fifty-two feet in heighth, and sixty in com. pass, ascending by many stories, having at bottom a battering ram, a machine of strength sufficient to beat down walls; in the middle a draw-bridge, to be let down upon the wall of the city attacked, in order to open a passage into the town for the assailants; and at top a body of men, who, being placed above the besieged, harrassed them without running any risk. An ancient historian ha'h trans. mitted to us an action of an engineer at Alexandria, which deserves a place here, In defending that city against the army of Julius Cæsar, who attacked it, he by means of wheels, pumps, and other machines, drew from the sea a prodigious quantity of water, which he afterwards turned upon the adverse army to their extreme annoy

ance.

In short, the art of war gave occasion for a great number of proofs of this kind, which cannot but excite in us the highest idea of the enterprizing genius of the ancients, and the vigour with which they put their designs in execution. The invention of pumps by Ctesibius; and that of water-clocks, automatical figures, wind. machines, cranes, &c. by Heron, who lived in the second century; and the other discoveries of the Grecian geometricians, are so very numerous, that it would exceed the limits of a chapter, even to mention them.

Should we pass to other considerations, we shall find equally in. contestable evidences of greatness of genius among the ancients, in the difficult, and indeed astonishing enterprizes in which they so successfully engaged. Egypt and Palestine still present us with

proofs of this, the one in its pyramids, the other in the ruins of Palmyra and Balbec *. Italy is filled with monuments, and the ruins of monuments, which aid us in comprehending the former magnificence of that people; and ancient Rome even now attracts much more of our admiration than the modern.

The greatest cities of Europe give but a faint idea of that gran. deur, which all historians unanimously ascribe to the famous city of Babylon, which being fifteen leagues in circumference, was encompassed with walls two hundred feet in height, and fifty in breadth, whose sides were adorned with gardens of a prodigious extent, which arose in terasses one above another, to the very summit of the walls; and for the watering of those gardens they had contrived machines, which raised the water of the Euphrates to the very highest of those terrasses; a height equalling that to which the water is carried by the machine of Marly. The tower of Belus, arising out of the middle of a temple, was of so vast a height, that some ancient authors have not ventured to assign the measure of it; others put it at a thousand paces.

Ecbatane, the capital of Media, was of immense magnificence, being eight leagues in circumference, and surrounded with seven walls, in form of an amphitheatre, the battlements of which were of various colours, white, black, scarlet, blue, and orange; but all of them covered with silver or with gold. Persepolis was also a city, which all historians speak of as one of the most ancient and noble of Asia. There remain the ruins of one of its palaces, which measured six hundred paces in front, and still displays the relics of its ancient grandeur.

The lake of Mæris is likewise a striking proof of the vast undertakings of the ancients. All historians agree in giving it above an hundred and fifty leagues in circuit; yet was it entirely the work of one Egyptian king, who caused that immense compass of ground to be hollowed, to receive the waters of the Nile, when it overflowed more than ordinary, and to serve as a reservoir for watering Egypt by means of its canals, when the overflowing of the river was not of height sufficient to enrich the country. Out of the midst of this Lake, arose two pyramids, of about six hun. dred feet in height.

* It is proper to remark that the temples and immense palaces of Palmyra, whose magnificence surpasses all other buildings in the world, appear to bave been built at the time when architecture was in its decline.

The other pyramids of Egypt, in their largeness and solidity, so far surpass whatever we know of edifices, that we should be ready to doubt of the reality of their having ever existed, did they not still subsist to this day. Mr. de Chezele, of the Academy of Sciences, who travelled into Egypt to measure them, assigns to one of the sides of the base of the highest pyramid, a length of six hundred and sixty feet, which reduced to its perpendicular altitude, makes four hundred sixty and six feet. The free. stones, of which it is composed, are each of them thirty feet long; so that we cannot imagine how the Egyptians found means to rear such heavy masses to so prodigious a height.

The Colossus of Rhodes was another of the marvellous produc. tions of the ancients. To give an idea of its excessive bigness, it need only be observed, that the fingers of it were as large as statues, and very few were able, with outstretched arms, to encompass the thumb*.

In short, what shall we say of the other structures of the ancients, which still remain to be spoken of? Of their cement, which in hardness equalled even marble itself; of the firmness of their highways, some of which were paved with large blocks of black marble; and of their bridges, some of which still subsist irrefra. gable monuments of the greatness of their conceptions? The bridge at Gard, three leagues from Nimes, is one of them. It serves at once as a bridge and an aqueduct. It goes across the river Gardon, and joins together the two mountains, between which it is inclosed. It comprehends three stories; the third is the aqueduct, which conveys the waters of the Eure into a great reservoir, which

* Plin. book 34, chap. 7, and Diodorus Siculus, book 2, relate that Semiramis made the mountain Bagistan, between Babylon and Media, be cut out into a statue of herself, which was seventeen stades high; that is, above half a French league; and around it were an hundred other statues, of proportionable size, though less large. And Plutarch, vol. 2, p. 335, speaks of a very great undertaking which one Stesicrates proposed to Alexander; viz. to make a statue of him out of Mount Athos, which would have been an hundred and fifty miles in circumference, and about ten in height. His design was to make him hold in his left hand a city, large enough to contain ten thousand inhabitants; and in the other an urn, out of which should flow a river, poured by him into theà. See also the same, Plutarch, vol. 1, p. 705, in the Life of Alexander. Vitruvius, in the preface to his 2d Book, gives to this statuary the name of Dinocrates. Strabo, lib. 14, p. 641, calls him Chiromocrates. Tzetzes, Chiliad. 8, 199.