PORTA, DECAUS AND KIRCHER.In our last article, we presented an illustration of Hero, the Grecian's steam engine, and stated that he had left manuscripts behind him that described his inventions. His work was called " Spiritalia," and when learning revived in Europe, in the fourteenth century, it formed the text book for the ingenious men who began to study mechanism Avoid of many centuries occurs in the history of the steam engine, which may be accounted for by the turbulence of those ages. Among the most tangible accounts which we have of the application of Bteam, after Hero, was by An-themius, an architect and mathematician, who lived in Constantinople in the early part of the sixth century. Having a quarrel with Zeno, a celebrated orator, the latter vanquished him in " tongueology," but the gabbler was ultimately defeated by the master mechanic, who lived in an adjacent house. In a lower room, Anthemius arranged several cauldrons of water, each of which was covered with the wide bottom of a flexible tube which tapered towards the top, and which were craftily conveyed among the joints and rafters of Zeno's house. When the cauldrons were heated, tho steam arose through the pipes, and acting upon the confined air, let off several discharges which shook the building and created such horrible sounds that the superstitious inhabitants thought they resembled the groans of suffering ghosts. Tho orator was made to succumb ; so he went to the Senate and in tragic style declared that "mere mortal must yield to the power of an antagonist who shook the earth with the trident of Neptune." Again, about 1125, as related by the chronicler, William of Malmsbury, there was in a church at Rheims, in continental Europe, an organ invented by Gerbert, a professor in the schools, which had brazen pipes that emitted modulated tones by air which was expanded by heated water. This was certainly the first Calliope. The next caloric inventor was Jerome Cardan, of Pavia, who lived in the early part of the sixteenth century. He was one of the most learned men in Europe, but a consummate quack and deeply superstitious. At the same time he was a distinguished mathematician and physician. In the writings which he left behind, he describes how a vacuum may be made in a vessel, by condensing steam ; and he left a rude diagram of a machine to be moved by the heated air which escaped from the fire on the hearththe well-known smoke-jack, and the first hot air engine. About this time (1540) practical mechanics began to receive greater attention. Besson, who taught philosophy at Orleans, in France, made a number of machines, the operation of which he explained in his lectures. In 1588, Agostino RamelH published a book in Paris in which several machines were described, and his writings show that he was engaged, like many persons in our day, in efforts to invent a perpetual motion that ignis Jatuus of mechanical ignorance. The next steam inventor is Baptista Porta, a Neapolitan nobleman, who invented the magic lantern, and who was a man of extensive learning and great mechanical attainments for that erathe sixteenth century. In the salubrious and warm clime of southern Europe, the early steam inventors had their attention drawn to the production of artificial fonntains, with their cooi and sparkling waters adorning the shady grove, the colonnade and piazza. In Fig. 7, we have an illustration of Porta's steam fountain ; a is a retort or steam vessel, having its neck inserted into the bottom of the cistern, c, which is nearly filled with water by the funnel, e. A pipe, o, passes through the corner ; the steam rises into the upper part of the cistern and by its expansive pressure it forces the water, in a silvery shower, up through the pipe, o, in its cover. Figs. 5 and 6 represent the steam fountains of Solomon Deeaus, who published a book on mechanics in 1615, at Frankfort, Germany, but who was a native of France, an engineer and architect of great acquisitions. Water is introduced into the copper globe, a, by the funnel. A pipe, i, is inserted into this globe. When fire is applied to the globe and steam is generated, it forces the water through the tube, i, by its expansive pressure, as the bottom of the exit pipe extends down below the surface of the water. The great idea of Decaus, however, was to generate steam without fire by the heat of the sun, so as to make an artificial fountain, as shown in Fig. 5, which represents a cistern partly filled with water, and having a lens inserted in it, for concentrating the rays of the sun to generate vapor in the upper part of the cistern, the elastic pressure of which forced the water up through the tube. The lower cistern has a pipe which leads to the upper one, in which is a valve opening upwards. A lens is made to concentrate the sun's rays upon this cistern ; the water flows into the upper one by the pressure of the vapor, and it cannot return owing to tho valve in tho lowerpipe. Thesecon-trivances never reached a higher position than curious steam toys. Fig. 4 represents the steam fountain of Kircher, a Jesuit, and professer of philosophy in Rome, in 1656. a is a boiler containing water; it is connected by a pipe, with another close vessel, from which a pipe, o, rises into the atmosphere. Fire being applied to the boiler, steam issues from its pipe and fills the upper part of the cistern, where its expansive pressure forces the water it contains in a jet up into the atmosphere. The principle is the same as Porta's apparatus, but is far more elegant in construction, and it was practically applied. The solar fountain of Decaus exhibits great ingenuity and much reflection. His method of concentrating the heat of the sun by lenses, for generating steam, has been proposed to us quite a number of times within the past few years.