Ru/pture of Vessels by Steam.

409

Chap 4.]

The diagram and description, observes Stuart, are so complete, that theapplication to such a purpose of a similar apparatus could not be consi-dered even as a Variation of Porta’s idea.

In the first histories of the modern steam engine, its origin was tracedto a de vice for raising water, proposed by the Marquis of Worcester, inhis Century of Inventions, a tract written in 1655 and published in 1663.Subsequent researches have brought to light facts (some of which havejust beeil noticed) which prove that steam was applied to that and otherpurposes long before ; and future inquiries will probably produce stillearlier examples. Previous to describing other old applications of thisfluid, we shall notice some experiments which historians of the steam en-gine have introduced. Thus Rivault, a French courtier, is said to have“ discovered” in 1605 that a tight bomb shell containing water and throwninto a fire would be exploded by the confined vapor—and by Decaus in1615, that a close copper ball partly filled with water and heated, wouldbe rent asunder with a noise resembling that of a petard—and by theMarquis of Worcester in 1663, that a piece of ordnance would also beexploded, if treated in the same way with its mouth and touch-hole plug-ged up. Now, the fact which these experiments established (if theywere all made) was one with which every person who ever used aneolipile was familiär ; and which was no more a new discovery in thebeginning of the seventeenth Century, than experiments to prove that thecover of a common cauldron might be blown off by the same agent, couldhave been in the middle of it. It was a knowledge of the same fact thatled ancient philosophers to account for the phenomenon of earthquakes—which induced the ministers of the steam deities, mentioned in the lastchapter, to regulate the resistance of the plugs which closed the mouthand eyes of the idols, so as to give way before the tension of the steamexceeded the strength of the metal, and blew both them and their gods toatoms. When the Spanish treasurer objected to the project of Garay thatthe boiler might “ burst,” he did not dream of having made a discovery ofthe danger arising from imprisoned steam : had such been the case his ob-jection would have had no force tili the fact upon which it was based, hadbeen tested and become generally known—but the ground of his Oppositionevery person of that age could appreciate as well as we can ; and it is notlmprobable that on that ground only was the project abandoned. Thesame objection still prevents thousands from traveling either in steam boatsor steam carriages.

Examples to show that old chemists were as familiär with the same factalmost as with “ the cracklings of thorns under a pot,” might be quoted inabundance—they are not necessary, but we shall adduce one or two. InPorta’s Natural Magic, (Book X, chap. 1, on Distillation,) he speaks of re-gulating the capacity of stills to the various substances treated in them.Such as were of “ a flat and vapourous nature” require, he observes, largevessels, “ for when the heat shall have raised up the flatulent matter, and itfinds itself straighten’d . . . . it will seek some other vent, and so tear thevessels inpieces , which will fly about with a great bounce and crack, and notwithout endamaging the Standers by.” Again, in the ninth chapter of thesame book,he directs that particular care should be taken to make the jointstight “ lest the force of the vapours arising may burst it [the still] openand scaid the faces of the by Standers.” That such occurrences were notuncommon may be inferred from another remark; (in the 21st chapter of thelOth book,) speaking of “ the Separation of the elements” and of the varioussubstances distilled, he observes, “ we account those airy which fill the ves-sels and receivers and easily burst them, and so flie out.” These examples