Page:Popular Science Monthly Volume 42.djvu/590

572 such things for once, without apparent immediate damage, but it is with great peril to their future vigor.

Famons Automatons.—Many ingeniously constructed automatons are mentioned in history or the fiction that goes with it. Among them are a wooden dove that was made b. c. 400; a fly presented to Charles V which went round in a circle and returned to its starting point; a bronze fly made by a bishop of Naples in the eleventh century which kept real flies out of the city; an eagle that flew before the Emperor Maximilian; and the brazen men that were made by Roger Bacon, or, according to others, by Albertus Magnus or Reysolius. A spider of the ordinary size was exhibited in London in 1810, which was caused by wheelwork to walk on a plate, and to shake its paws when taken hold of. A swan was on view about the same time, swimming in a basin of water along with some fish. It would seize a fish, swallow it, and then shake its wings. A few years afterward a gold bird appeared, which would come out of a tobacco box, spread its wings, and sing. The famous automaton chess-player was a humbug. It was not moved by machinery, but by a man hidden inside. Some very curious automatons were constructed by Vaucanson in the eighteenth century. Among them were a flute-player which played a dozen airs, and another performer which played twenty different tunes with a tambourine and a flageolet. These "artists" were worked by a strong spring that acted on numerous whistles supplied with air from reservoirs which were opened at the proper times. Vaucanson also made an asp for Marmontel's Cleopatra theatre, which could coil itself, thrust out its tongue, and hiss. His duck was a very famous imitation; for it could move its head around in search of food, swallow, and "digest." The secret of its "digesting" was discovered by Robert Houdin when he was engaged in repairing it. The food that was given it was removed during the intervals between the exhibitions and suitable "digested" matter, or the imitation of it, supplied. Houdin was very ingenious and was employed to repair other complicated machines. Among them was a mechanical organ that could improvise variations, that had been taken to pieces without marking where the several parts belonged. He succeeded in putting it together again, but it is not known what eventually became of it. The visitors to a certain seminary in the old times were met at the door by an automatic skeleton which welcomed them by clapping its fleshless finger-bones.

Periodical Variations of Glaciers.—The question of the periodicity of changes in the glaciers of the Alps is hereafter to be studied systematically. It has been taken up by the Council of the Canton of Le Valais, which has put the matter in charge of the administration of forests. A report made by M. Forel to the head of the Home Department represents that glaciers in general, and particularly those of Le Valais, are subject to variations in shape, which, according to an irregular periodicity, cause them sometimes to grow in length, in breadth, and in thickness, and sometimes to decrease, often in very considerable proportions. It has been recognized that most of the great catastrophes which have ravaged the region of the high Alps have been caused by these glacial variations. It is when the glacier extends, lengthens, and arrives at its maximum, that it invades the fields and destroys Alpine chalets, barricades the valleys, arrests the flow of rivers, and creates temporary lakes, the evacuation of which devastates the country; or else, surpassing its usual dimensions, it forms an avalanche, the destructive power of which is terrible. The preparatory study of these variations that has been made in the last few years has shown that their periodicity is much longer than was formerly believed to be the case; the popular dictum that the increase in size of glaciers recurs every seven years is certainly incorrect. Definite figures can not yet be given, but probably the cycle of glacial variation is as much as from thirty-five to fifty years. If 1850 or 1855 be fixed upon as the epoch of maximum, they have been steadily decreasing in past years, so that from 1870 to 1875 not a single glacier was known to be on the increase. Since then an increase appears to have begun in the glaciers of the Mont Blanc group, but most of the others are still retreating or stationary. Hence the phenomenon is one of which a man in an ordinary lifetime can see only a single