Again, Van Etten in the fifth section of Problem LXXXV. treats--“Of a fine fountaine which spouts water very high, and with great violence by turning of a cock.” page 193. “Let there be a vessel made close in all its parts, in the middle of which let a pipe open neare the bottome; and then with a squirt squirt in the water (stopped above by the cock or faucet) with as great violence as possible you can, and turne the cock immediately. Now there being an indifferent quantity of water and aire in the vessel, the water keeps itself in the bottom, and the aire which was greatly pressed, seeks for more place, that turning the cock the water issueth forth at the pipe, and flyes very high, _and that especially if the vessell be a little heated_.” The concluding sentence would no doubt afford a mind like that of the Marquis of Worcester’s abundant matter for experimental trial, if ever consulted by him, either in the original, or in the translation of 1633. The following extract from Van Etten’s 83rd Problem, “Of Cannons or great Artillery,” affords strong presumptive evidence (taken along with other extracts) of the Marquis’s acquaintance with the work. The Problem is divided into two parts, of which the first alone need be noticed, namely,--“How to charge a cannon without powder.” It is observed--“This may be done with aire and water, only having thrown cold water into the cannon, which might be squirted forceably in by the closure of the mouth of the piece, that so by this pressure the aire might more condense, then having a round piece of wood very just, and oiled well for the better to slide, and thrust the bullet when it shall be time. This piece of wood may be held fast with some pole, for feare it be not thrust out before his time: _then let fire be made about the trunnion or hinder part of the piece to heat the aire and water_, and then when one would shoot it let the pole be quickly loosened, for then the aire searching a greater place, and having way now offered, will thrust out the wood and the bullet very quick: the experiment which we have in long trunkes [tubes] shooting out pellats with aire only, sheweth the verity of this Probleme.” (page 173.) The words italicised are a complete description of the Marquis’s experiment, although made with a widely different object, but both afford evidence of the force obtainable from a small quantity of heated water, the one in an imperfectly closed, the other in a well closed cannon. It is remarkable how near this experiment comes to the steam-engine cylinder, piston, and safety valve; and we can scarcely believe that such applications would escape the Marquis’s observation, when repeated and varied as was his customary course in pursuing his own inquiries.