405

Chap. 4.] Observations cm Oaray’s Steam Apparatus.

serves, “ manuscript documents cannot have any value with the public,because, generally, it has no means whatever of verifying the date as-signedto thera.” To a limited extent this may be admitted. Respectingprivate MSS. it may be true; but surely ojjicial and national records likethose referred to by the Spanish secretary should be excepted. Wehave in the eighth chapter of’ our Third Book quoted largely from officialMS. documents belonging to this city, (New-York :) now these are pre-served in a public office and may be examined to verify our extracts aswell as their own authenticity : and the Spanish records we presume areequally accessible, and their authenticity may be equally established. Themere printing of both could add nothing to their credibility, although itwould affbrd to the public greater facilities of judging of their Claims to it.So far from rejecting such sources of information respecting the arts offormer times, we should have supposed they were unexceptionable.

But it is said—although a boiler is mentioned, that is not sufficient proofthat steam was the impelling agent, since there are various machines inwhich fire is used under a boiler, without that fluid having any thing todo with the operations : Well, but the account States that which reallyappears conclusive on this point, viz. that this vessel contained “ boilingwater ” and that Ravago the treasurer, opposed the scheme on the groundthat there would be an exposure to danger “ in case the boiler shouldburst.” As this danger could not arise from the liquid contents merely,but from the accumulation of steam, (the irresistible force of which was,as has been observed, well known from the employment of eolipiles) it isobvious enough that this fluid performed an essential part in the Opera-tion—in other words was the source of the motive power. Had it notbeen necessary, Garay would never have furnished in, it such a plausiblepretext for Opposition to his project. It has been also said “ if we wereto admit that the machine of Garay was set in motion by steam, it wouldnot necessarily follow that the invention [steam engine] was new, andthat it bore any resemblance to those of our day.” • True, but it wouldat least follow that Garay should be considered the father of steam navi-gation, until some earlier and actual experiment is produced. Arago furtherthinks, that if Garay used steam at all, his engine was the whirlingeolipile (No. 180)—“ every thing” he observes would lead us to believethat he employed this. We regret to say there are strong objections tosuch an opinion. That an engine acting on the same principle of recoilas Heron’s eolipile might have been made to propel a vessel of two hun-dred tons is admitted ; but from modern experiments with small enginesof this description, we know; Ist, that in Order to produce the reportedresult, the elasticity of the steam employed must have been equivalent toa pressure of several atmospheres ; and 2d, that the enormous consump-tion of the fluid when used in ohe of these engines must have requiredeither a number of boilers or one of extraordinary dimensions. HadGaray employed several boilers, the principal diffieulty would be removed,as he might then have made them sufficiently strong to resist the pressureof the confined vapor; he however used but one, and every person whohas witnessed the Operation of reäcting engines will admit that a singleboiler could hardly have been made to furnish the quantity of steam re-quired, at the requisite degree of tension.

As the nature of this Spanish engine is not mentioned, every person isleftto form his own opinion of it. We see no diffieulty in admitting thathe employed the elastic force of steam to push a piston to and fro—orthat he formed a vaeuum under one by condensing the vapor. Such ap-plications of steam were as likely to occur to a person deeply engaged in