About this period, however, frequent mention is made of other modes of propulsion besides those hitherto in use. J. C. Scaliger (who died 1558) published at Frankfort a short notice of a vessel to be propelled without oars. Bourne, in 1578,[18] says, in his own quaint style, “you may make a boate to goe without oares or sayle by the placing of certain wheeles on the outside of the boat in that sort that the armes of the wheeles may go into the water, and so turning the wheeles by some provision, and so the wheeles shall make the boate goe.” I. Bessoni, in 1582, describes a vessel with two prows, or rather two separate vessels attached to each other (not unlike the _Castalia_, now running between Dover and Calais), between which a frame is suspended on gimbles carrying at its lower end a circular reel worked by ropes and a winch whereby they can be propelled.[19] A. Ramelli, in 1588, furnishes a design of a flat-bottomed boat with a wheel on each side, turned by men working upon a winch handle.[20] Indeed, long before this, the celebrated Roger Bacon (A.D. 1214-1296) speaks of a “vessel which, being almost wholly submerged, would run through the water against waves and winds with a speed greater than that attained by the fastest London pinnaces.”[21] Baptista Porta (the inventor of the magic lantern) published in his “Pneumaticorum Libri Tres,” Naples, 1601, many curious experiments on the power of steam, on its condensation, and on its relative bulk as compared with water. In one of these a vacuum is clearly indicated, the water being forced up by the pressure of the atmosphere from without. David Rivault, Seigneur de Flurance near Laval, published “Les Éléments de l’Artillerie,” first in 1605 and secondly in 1668—and in this work he describes the power of steam in bursting a strong bomb-shell partly filled with water, tightly plugged, and then heated. In 1615, Solomon de Caus (Engineer to Louis XIII.) published a treatise (“Les Raisons des Forces Mouvantes”) in which he shows he was well acquainted with the motive power of steam—as, in his fifth theorem, he says, “water will mount by the help of fire higher than its level:” he also shows, by an experiment, how a column of water may be driven up a tube to such a height as will balance the elasticity of the heated air confined in the boiler; and Arago, in his “Éloge de James Watt,” considers that this experiment, though of little practical use, “will make a noble figure in the annals of the steam-engine.” In 1629, Giovanni Branca, an engineer of Loretto, applied steam to blow against vanes attached to the external rim of a wheel, and, doubtless, machinery with due mechanical contrivances could have been impelled by it. He gives a picture of his machine in “Le Machine,” vol. nuovo, Pl. XXV.