ways; and if the butt end of the piece were so fixed that the gun could move as upon a centre, it would revolve, and if the discharge were continuous so also would be the rotation. The arms of Hero's machine were constructed in this way, and had a similar motion, the speed and power being increased according to the number of the arms. The same principle is adopted in Barker's mill, water being used instead of steam. This is the first instance on record of the production of motion by steam. The instrument is called an æolipile. The word has been variously spelt, but appears to be derived from two latinized Greek words, Æoli-pila, signifying the ball of Æolus-an appropriate designation. Since the time of Hero, the æolipile has been applied for various purposes, but from its want of power it deserves to be called a toy rather than a useful engine.

Sir Hugh Plat, in his "Jewel House of Art and Nature," published in 1653, describes an æolipile, which he says is a round ball of copper or latten, that will blow the fire very strongly, onely by the attenuation of water into air, which device may also serve to perfume with."

Plat, in his "Natural History of Staffordshire," (1686,) gives a description of a steam generator, and relates its curious connexion with a feudal tenure. "There are many old customs in use within memory, of whose originals I could find no tolerable account; such as the service due from the lord of Essington, in this county, to the lord of Hilton, about

a mile distant, viz., that the lord of the manor of Essington shall bring a goose every Newyear's Day, and drive it round the fire in the hall of Hilton, at least three times, which he is bound to do as a mean lord, whilst Jack of Hilton is blowing the fire. Now Jack of Hilton is a little hollow image of brass of about twelve inches high, kneeling upon his left knee, and holding his right hand upon his head, having a little hole in the place of the mouth about the bigness of a great pin's head, and another in the back about two-thirds of an inch in diameter, at which last hole it is filled with water, it holding about four pints and a quarter, which, when set to a strong fire, evaporates in the same manner as in the solipile, and vents itself at the smaller hole at the mouth in a constant blast, blowing the fire so strongly that it is very audible, and makes a sensible impression in that part of the fire where the blast lights, as I found by experience, May the 26th, 1680."

In 1629, Branca, an Italian architect, published a work descriptive of a machine which consisted of an æolipile projecting a current of steam upon the floats of a wheel, and the same thing seems to have been done by the Jesuits in China, to amuse the emperor Kanghi, who died in 1722. Père du Halde, in his "History of China," says, "They caused a wagon to be made of light wood about two feet long, in the middle of which they placed a brazen vessel full of live coals, and upon them an æolipile, the

wind of which issued through a little pipe upon a sort of wheel made like the sail of a windmill. This little wheel turned another with an axletree, and by that means the wagon was set a running for two hours together; but for fear there should not be room enough for it to proceed constantly forwards, it was contrived to move circularly in the following manner :-to the axletree of the two hind wheels was fixed a small beam, and at the end of this beam another axletree passed through the stock of another wheel somewhat larger than the rest; and, accordingly, as this wheel was nearer or further from the wagon, it described a greater or less circle. The same contrivance was likewise applied to a little ship with four wheels; the æolipile was hidden in the middle of the ship, and the wind issuing out of two small pipes filled the little sails, and made them turn about a long time. The artifice being concealed there was nothing heard but a noise like wind, or that which water makes about a vessel."

Hero, with whom these experiments appear to have commenced, did not always innocently apply his learning or discoveries, and in this respect also he was followed by other ingenious but unscrupulous men. Error is ever ready to receive the assistance of science in imposing on its victims; but science is never so disgraced as when it condescends to help the impostor. The gross idolatrous superstitions of Greece and Rome at no period received the hearty belief of the learned, and yet from a pride of superior

knowledge, and an anxiety to keep the poorer classes in ignorance, they were always ready to assist in making more dense the thick darkness that covered the earth. In the temples of idols the largest and most ingenious of Hero's works were erected, to deceive the people and perpetuate the dominion of a degraded and cruel priesthood. Nor was he ashamed to record the fact, or describe the mode in which he practised the deception. In one of these temples he so contrived his apparatus as to convey wine through pipes from vases to the hands of two figures standing by the altar of sacrifice, and by the same agent, steam, produced "sibylline sounds" from the mouth of a golden dragon. In another temple, figures were made to dance round an altar by being attached to a large drum, revolving by the force of issuing steam. By such contrivances as these, which in the present day would scarcely amuse the idle spectators of a puppet-show, the volatile Greek and the brutal Roman populace were held in obedience to the priests of false gods, and confirmed in the indulgence of all those sensual and unholy practices, so conformable to the natural depravity of the human heart, and which were so intimately bound up with the rites of idolatry.

Arago, in his "Life of Watt," gives another instance of the adaptation of scientific discovery to the purposes of deception. "Ancient history," he writes, "has informed us that on the banks of the Weser, the god of the Teutones of

old sometimes showed himself unpropitiously by a sort of thunder-clap, immediately succeeded by a cloud, which filled the sacred inclosure. The statue of the god Busterich, discovered, it is said, in the course of excavation, clearly shows the method by which the pretended miracle was effected. The god was of metal; the head was hollow, and contained an amphora (about nine English gallons) of water; wooden plugs closed up both the mouth and another opening above the forehead; live coal, dexterously placed in a cavity of the skull, gradually heated the liquid. Very soon the steam generated forced out the plugs with a loud report; it then escaped with violence in two streams, and raised a thick cloud between the deity and his stupified worshippers. It would appear that in the middle ages some monks found their account in this invention, and that the head of Busterich has performed its office before other than Teutonic multitudes." Evidences are too numerous and too strong to leave a doubt of the frequent use of physical phenomena by the Roman church as miraculous interventions of God and spiritual beings. A priesthood driven to such subterfuges to maintain a character for sanctity must be in the deepest state of degradation. It is only for a time, however, that a religion can be supported by such hollow pretences, and hold an ignorant people in mental thraldom and spiritual darkness. The influence of habit and the authority of prescription are not easily broken