PART III.

HISTORY AND DESCRIPTION OF THE STEAMENGINE.

163. It is very interesting to trace the progress of a great invention, from the first rude attempts, till it attains a somewhat perfect form-to mark the successive changes it undergoes, and observe how often men have been on the very brink of the discovery, and yet allowed it to escape them; and there is, perhaps, no better or easier way to understand the later and more complex forms it assumes, than tracing it from the first simple conception, and at each stage contrasting it with its previous condition. We shall, therefore, prefix to the description of the modern engine, a brief sketch of the progress of the invention from the earliest records.

SECTION I.

Æolipile of Hero-Organ of Gerbert-Garay's Steamboat-Fountain of Porta and Kircher-Engines of De Caus, Branca, Worcester, and Moreland-and Papin's First Engine.-130 B.c. to 1690.

EOLIPILE.-B.C. 130.

164. The first instance on record of the force of steam being applied to produce motion, is that of the

Æolipile, a philosophical toy, described in the writings of Hero of Alexandria, who flourished during the reign of Ptolemy Philadelphus, about 130 years before the birth of Christ. This writer was distinguished for his mechanical knowledge. Besides the Æolipile, described in the next paragraph, he also was acquainted with the forcing-pump for raising water, (the invention of Ctesibius ;) the beautiful contrivance for an artificial fountain, still called Hero's fountain; a machine for producing a rotatory motion by a jet of heated air; and many other curious mechanical inventions. The following cut will explain the action of the Æolipile.

b

FIG. 8.

This consists of a globular metallic vessel, a, revolving on two pivots, the pointed extremities of the tubes, b. c., and having two tubes, e.e., proceeding from it at right angles to the line of the pivots. The tubes, b. c., proceed from a steam-boiler, d, and, by small apertures at their extremities, convey the steam which is generated into the globe a. The tubes ee are closed at the

extremities, but have each an aperture at one side, by which the steam issues. One tube (e) would do; but where there are two, the apertures must be on the opposite sides of the tubes, as seen in the little figure at the

side. Or, instead of apertures, the tubes e e may be open at the ends, if they be bent near the extremity at right angles, and in directions opposite to each other. The steam will issue with great force at the apertures, and, acting on the side of the tube opposite to the aperture, will cause it, and the globe along with it, to move in a direction opposite to that in which the steam issues; and, the supply of steam being kept up, a continuous rotatory motion of the machine will be induced. There may be several tubes (e e e.)

166. The same may be effected in a simpler way, by forming the steam in the vessel a itself, the globe being removed from the boiler and tubes bc, and made to revolve on supports, by rods projecting from its surface in the line of the notches. This was proposed, in a book published at Leipsic in 1597, as a means of turning a spit for roasting meat.

167. The principle of the Æolipile-the same as that which produces the motion in the machine called Barker's Mill—has not till lately been made use of in any modern engine; but it unquestionably exhibits motion produced by the force of steam, and which might be transferred to machinery for some useful purpose. It has the merit of great simplicity, and has lately been proposed as a moving power by an American engineer. with what success is not yet known. See " Avery's Engine," in the chapter on Rotatory Engines.

168. Hero also describes a machine for raising water (it would do so, certainly-but in drops only) by the action of the sun's rays on the air in a globe two-thirds full of water, the air expanding and pressing the water through a tube. And this description seems to have suggested to Baptista Porta the contrivance described in paragraph 172, (which is, in fact, a steam-engine,) and to De Caus some of his ingenious machines for indicat

H

ing the heat of the weather, raising water by the sun's heat, &c.

ORGAN OF GERBERT.-12TH CENTURY.

169. In his "Historical and Descriptive Anecdotes of Steam-Engines," and of their inventors and improvers a very interesting work-Mr Robert Stuart has pointed out a passage in Malmsbury's "History," from which it would appear, that, about the 12th century (1125), there was at Rheims an organ, in which steam (heated water is the term) was in some way instrumental in producing the sounds. The passage is as follows:-" In the church of Rheims, are still extant, as proofs of the knowledge of Gerbert-a public professor of the schools-a clock constructed on mechanical principles, and an hydraulic organ, in which the air, escaping in a surprising manner by the force of heated water, fills the cavity of the interior of the instrument, and the brazen pipes emit modulated tones through the multifarious apertures." It does not appear whether steam was actually used, or the heated water only employed to expand the air, as the words would almost indicate; if the former, this is certainly the first useful application of steam.

STEAMBOAT OF GARAY.-1543.

170. At Barcelona, in the year 1543, a Spanish seaofficer, called Blasco de Garay, propelled a vessel on the water without sails or oars, "by an apparatus, of which a large kettle filled with boiling water was a conspicuous part." From the reports and records, it

appears that the experiment-which was done by order of the famous Emperor Charles V.was considered as successful, and that Garay was promoted and rewarded. But it went no further-perhaps, as Dr Renwick remarks, because he was "too far in advance of the spirit of his age to be able to introduce his invention into practice;" and it died with him, as he kept his plan strictly secret. If this account be authentic, Garay must have possessed, considering the times, an extraordinary degree of knowledge of the properties of steam, and of mechanical skill.

171. A German writer, called Mathesius, in a volume of sermons published in 1571-a rather singular place, certainly describes an apparatus somewhat resembling a steam-engine, and speaks of the " mighty effects could be produced by the volcanic force of a little imprisoned vapour." Between that time and the end of the next century, when Savery constructed his engine, there are many notices by various authors of the effect of heat upon water-" the power of imprisoned vapour"-and hints for the construction of engines founded thereon. We shall allude to Porta, De Caus, Branca, Worcester, Morland, and Papin.

BAPTISTA PORTA.-1606.

"

172. The celebrated Baptista Porta, an Italian philosopher, inventor of the Camera Obscura, was the author of several ingenious works, and, among others, a commentary on the "Pneumatica of Hero, in which he describes and gives a drawing of a steamfountain, which wanted nothing but the "idea of such an application," and a proportional magnitude, to form