was present they dared not even to make the attempt, in the manner at least which Archimedes was able to oppose. They therefore determined to ravage the surrounding country, and intercept all supplies from sea, and thus, after a protracted struggle, starved the Syracusans into surren der. To the great grief of Marcellus, Archimedes was killed in his study by a soldier who did not know the person of the philosopher.

Such is the account of this famous siege as narrated by Polybius, and we shall now examine into the subject of the burning glasses, with which Archimedes fired the Roman fleet, referring such of our readers who may desire to make further inquiries to an excellent work by the rev. Mr. Dutens, on the "Origin of the Discoveries attributed to the Moderns," which contains much instructive matter on antiquities in general.

Tzetzes says that "Archimedes set fire to Marcellus' navy by means of a burning glass composed of small square mirrors, moving every way upon hinges; which, when placed in the sun's rays, directed them upon the Roman fleet, so as to reduce it to ashes, at the distance of a bow shot." We have before remarked that Kepler, Naudeus, and Descartes, have pronounced the whole a fiction. Father Kirker, a learned Jesuit, attentively observing the description which Tzetzes has recorded, resolved to prove the possibility of the experiment, and having, by means of a number of plain mirrors, collected the sun's rays into one focus, he so augmented the solar heat, that, at last, by increasing the number of mirrors, he could produce the most intense degree of it. It is probable that Buffon availed himself of this description in constructing his burning glass, composed of one hundred and eight little plain mirrors, which produced so considerable a heat as to set wood in flames at the distance of two hundred and nine feet; melt lead at that of one hundred and twenty, and silver at that of fifty.

Another testimony occurs, which leaves not the least doubt in this case, but resolves all in favour of Archimedes. Anthemius, of Tralles in Lydia, a celebrated architect, able sculptor, and learned mathematician, who, in the emperor Justinian's time, built the church of Sancta Sophia, at Constantinople, wrote a small treatise in Greek, which is entitled, "Mechanical Paradoxes." That work has a chapter respecting burning glasses, where we meet with the most complete description of the requisites that Archimedes, according to this author, must needs have been possessed of, to enable him to set fire to the Roman fleet. He begins with this inquiry: "How, in any given place, at a bow shot's distance, a conflagration may be raised by means of the sun's rays?" And immediately he lays it down as a first principle, "that the situation of the place must be such, that the rays of the sun may be reflected upon it in an oblique, or even opposite direction, to that in which they come from the sun itself." And he adds, "that the assigned distance being so very considerable, it might appear at first impossible to effect this by means of the reflection of

the sun's rays; but as the glory Archimedes had gained by thus setting fire to the Roman vessels was a fact universally admitted, he thought it reasonable to grant the possibility of it, upon the principle he had laid down." He afterwards advances further in this inquiry, establishing certain necessary propositions in order to come at a solution of it. "To find out, therefore, in what position a plain mirror should be placed to carry the sun's rays by reflection to a given point, he demonstrates that the angle of incidence is equal to the angle of reflection; and having shown that in so just a position of the glass the sun's rays might be reflected to the given place, he observes, that by means of a number of glasses reflecting the rays into the same focus, there must arise at the given place the conflagration required, for inflammatory heat is the result of thus concentrating the sun's rays, and that, when a body is thus set on fire, it kindles the air around it, so that it comes to be acted upon by the two forces at once, that of the sun, and that of the circumambient air, reciprocally augmenting and increasing the heat; whence it necessarily results, that by a proper number of plain mirrors duly disposed, the sun's rays might be reflected in such quantities into a common focus, at a bow shot distance, as to set all in flames around it."

As to the manner of putting this into practice, Anthemius says, "it might be done by employing many hands to hold the mirrors in the described position; but to avoid the confusion that might thence arise, twenty-four mirrors at least being requisite to communicate flame at such a distance, he fixes upon another method, that of a plain hexagon mirror, accommodated on every side by lesser ones, adhering to it by means of plates, bands, and hinges, connecting them mutually together, so as to be moved or fixed at pleasure in any direction. Thus, having adapted the large or middle mirror to the rays of the sun, so as to point them to the given place, it will be easy in the same manner to dispose the rest, so that all the rays together may meet in the same focus; and by multiplying compound mirrors of the same kind, and giving them all the same direction, there must thence infallibly result, to whatever degree of intenseness, the conflagration required at the place given. The better to succeed in this enterprize, there should be in readiness a considerable number of those compound mirrors, to act all at once, from four at least He concludes his dissertation with observing, "that all the authors who mention the burning machine of the divine Archimedes, never speak of it as of one compound mirror, but as a combination of many."

So copious and accurate a description is more than sufficient to demonstrate the possibility of a fact so well attested in history, and by such a number of authors, that it would be the highest degree of arrogance and conceit to refuse our suffrage to such invincible testimony. Vitellion, who lived about the thirteenth century, speaks of a work of Anthemius of Vol. I.-No. 2. 7

Tralles, "who had composed a burning glass, consisting of twenty-four mirrors, which, conveying the rays of the sun into a common focus, produced an extraordinary degree of heat." Lucian, speaking of Archimedes, says, "that at the siege of Syracuse he reduced, by a single contrivance, the Roman ships to ashes." And Galen observes, that "with burning glasses he fired the ships of the enemies of Syracuse." Zonaras also speaks of Archimedes' glasses, in mentioning those of Proclus, "who burnt the fleet of Vitellius, at Constantinople, in imitation of Archimedes, who set fire to the Roman fleet at the siege of Syracuse." He intimates that the manner wherein Proclus effected this, was by launching on the enemies' vessels, from the surface of reflecting mirrors, such a quantity of flame as reduced them to ashes.

Eustathius, in his Commentary upon the Illiad, says, that " Archimedes, by a catoptric machine, burnt the Roman fleet at a bow shot's distance." Indeed there is scarce any fact in history warranted by more authentic evidence, so that it would be difficult not to admit the truth of it, even though we could not comprehend how it were possible for Archimedes to have constructed such glasses; but now that the experiments of Kirker and Buffon have made it apparent that nothing is more easy in the execution, what ought we not to think of the genius of that man whose inventions have surpassed the conceptions of such able mathematicians as Kepler and Descartes !

Again, it appears that the ancients were acquainted with refracting burning glasses, for we find in Aristophanes's comedy of the Clouds, a passage which clearly treats of the effects of those glasses. The author introduces Socrates as examining Strepsiades about the method he had discovered for getting clear for ever of his debts. He replies, that "he thought of making use of a burning glass, which he had hitherto used in kindling his fire; for," says he, "should they bring a writ against me, I'll immediately place my glass in the sun, at some little distance from the writ, and set it on fire." Where we see he speaks of a glass which burned at a distance, and which could be no other than a convex glass. Pliny and Lactantius have also spoken of glasses that burnt by refraction. The former calls them balls or globes of glass, or chrystal, which, exposed to the sun, transmit a heat sufficient to set fire to cloth, or corrode away the dead flesh of those patients who stand in need of caustics; and the latter, after Clemens Alexandrinus, takes notice that fire may be kindled by interposing glasses filled with water between the sun and the object, so as to transmit the rays to it.

We duly appreciate the mighty effects of modern machinery, but the inventive genius of Archimedes has never been surpassed. Leibnitz, who was one of the greatest mathematicians of his age, did justice to the philosopher of Syracuse, 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 has he diffused over the mathematics 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 sagacity did he give in discovering the quantity of silver that was mixed with the gold in the crown of king Hiero, whilst he reasoned on the 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 also invented a perpetual screw, valuable on account of its being able to overcome any resistance; and the screw that still goes by his own name, used in elevating water. He once said to his patron, friend, and admirer, king Hiero, "Give me but some other place to stand upon, and I will set the earth itself in motion;" and when the king, amazed at what he uttered, seemed to hesitate an answer, he gave him a striking proof of the probability of what he said, by launching singly by himself a ship of a prodigious size. He built likewise, for this king, an immense galley, of twenty banks of oars, containing spacious apartments, garden, walks, ponds, and all other conveniences suitable to the dignity of a great monarch. He constructed also a sphere, representing the motion of the stars, which Cicero esteemed one of the inventions that 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.

But the defence of Syracuse would alone immortalize the name of Archimedes. He was in himself truly a host. Sometimes he hurled on the land forces of the enemy stones of such an enormous size, as crushed whole bodies of them at once, and put the whole army into confusion. When they retreated 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 swinging them up in the air, to the stupor of all beholders, 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, wrapt them in sudden and inevitable conflagration.

ON THE SIGNS OF THE WEATHER.

WHEN bats remain longer than usual abroad from their holes, fly about in great numbers, and to a greater distance than usual, it announces that the following day will be warm and serene; but if they enter houses, and send forth loud and repeated cries, it indicates bad weather. If the owl is heard to scream during bad weather, it announces that it will become fine. The croaking of crows in the morning indicates fine weather. When the raven croaks three or four times, extending his wings, and shaking the leaves, it is a sign of serene weather. It is an indication of rain and stormy weather when ducks and geese fly backwards and forwards, when they plunge frequently into the water, and begin to send forth cries and flutter about. If bees do not remove to a great distance from their hives, it announces rain; if they return to their hives before the usual time, it may be concluded that it will soon fall. If pigeons return slowly to the pigeon house, it indicates that the succeeding days will be rainy. It is a sign of rain or wind when sparrows chirp a great deal, and make a noise to each other to assemble. When fowls and chickens roll in the sand, more than usual, it announces rain: the same is the case when cocks crow in the evening, or at uncommon hours. Peacocks, which cry during the night, have a presentiment of rain. It is believed to be a sign of bad weather when swallows fly in such a manner as to brush the surface of the water, and to touch it frequently with their breasts and wings. The weather is about to become cloudy and change for the worse, when flies sting and become more annoying than usual. When gnats collect themselves before the setting of the sun, and form a sort of vortex in the shape of a column, it announces fine weather. When sea fowl and other aquatic birds retire to the sea-shore or to marshes, it indicates a change of weather and a sudden storm. If cranes fly exceedingly high, in silence, and ranged in order, it is a sign of approaching fine weather; but if they fly in disorder, or immediately return with cries, it announces wind. When dolphins sport and make frequent leaps, the sea being tranquil and calm, it denotes that the wind will blow from the quarter whence they proceed. If frogs croak more than usual; if toads issue from their holes in the evening in great numbers; if the earth-worms come forth from the earth, and small scorpions appear on the walls; if ants remove their eggs from the small hills; if moles throw up the ground more than usual; if asses frequently shake and agitate their ears; if hogs shake and spoil the

2