Stories of Invention, Told by Inventors and their Friends

by Edward Everett Hale

The boys were highly edified by this statement of the difficulty which Archimedes's friends found in making him take a bath, and chaffed Jack, who had asked if he were not the inventor of bath-tubs.

When the reading from Plutarch was over, Fergus asked if that were all, and was disappointed that there was nothing about the setting of ships on fire by mirrors. It is one of the old stories of the siege of Syracuse, that he set fire to the Roman ships by concentrating on them the heat of the sun from a number of mirrors. But this story is not in Livy, nor is it in Plutarch, though, as has been seen, they were well disposed to tell what they knew which was marvellous in his achievements. It is told at length and in detail by Zonaras and Tzetzes, two Greek writers of the twelfth century, who must have found it in some ancient writers whose works we do not now have.

"Archimedes," says Zonaras,[3] "having received the rays of the sun on a mirror, by the thickness and polish of which they were reflected and united, kindled a flame in the air, and darted it with full violence upon the ships, which were anchored within a certain distance, in such a manner that they were burned to ashes."

The same writer says that Proclus, a celebrated "mathematician" of Constantinople, in the sixth century, at the siege of Constantinople set fire to the Thracian fleet by means of brass mirrors. Tzetzes is yet more particular. He says that when the Roman galleys were within a bow-shot of the city walls, Archimedes brought together hexagonal specula (mirrors) with other smaller ones of twenty-four facets, and caused them to be placed each at a proper distance; that he moved these by means of hinges and plates of metal; that the hexagon was bisected by the meridian of summer and winter; that it was placed opposite the sun; and that a great fire was thus kindled, which consumed the ships.

Now, it is to be remembered that these are the accounts of writers who were not so good mechanics as Archimedes. It should be remembered, also, that in the conditions of war then, the distance at which ships would be anchored in a little harbor like that of Syracuse was not great. By "bow-shot" would be meant the distance at which a bow would do serious damage. Doubtful as the story of Zonaras and Tzetzes seems, it received unexpected confirmation in the year 1747 from a celebrated experiment tried by the naturalist Buffon.

After encountering many difficulties, which he had foreseen with great acuteness, and obviated with equal ingenuity, Buffon at length succeeded in repeating Archimedes's performance. In the spring of 1747 he laid before the French Academy a memoir which, in his collected works, extends over upwards of eighty pages. In this paper he described himself as in possession of an apparatus by means of which he could set fire to planks at the distance of 200 and even 210 feet, and melt metals and metallic minerals at distances varying from 25 to 40 feet. This apparatus he describes as composed of 168 plain glasses, silvered on the back, each six inches broad by eight inches long. These, he says, were ranged in a large wooden frame, at intervals not exceeding the third of an inch, so that, by means of an adjustment behind, each should be movable in all directions independent of the rest; the spaces between the glasses being further of use in allowing the operator to see from behind the point on which it behooved the various disks to be converged.

In this last statement there is a parallel with that of Tzetzes, who speaks of the division of Archimedes's mirrors.

At the present moment naturalists are paying great attention to plans for the using of the heat of the sun. It is said that on any county in the United States, twenty by thirty miles square, there is wasted as much heat of the sun as would drive, if we knew how to use it, all the steam-engines in the world.

Fergus asked Uncle Fritz if he believed that Archimedes threw seven hundred pounds of stone from one of his machines. The largest modern guns throw shot of one thousand pounds, and it is only quite recently that any such shot have been used.

Uncle Fritz told him that in the museum at St. Germain-en-Laye he would one day see a modern catapult, made by Colonel de Reffye from the design of a Roman catapult on Trajan's Column. This is supposed to be of the same pattern which is called an "Onager" in the Latin books. This catapult throws, when it is tested, a shot of twenty-four pounds, or it throws a sheaf of short arrows. In one catapult the power is gained by twisting ox-hide very tightly, and suddenly releasing it. Another is a very stout bow, worked with a small windlass. Of course this will give a great power.