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only such holes as are essentially necessity, that it maybe better able to support a long continuance of vehe-ment fire.

The furnace for this intention consists of two largepots: the lowermost of which has only a round hole inthe bottom for admitting air; and the upper one, ordome, a similar hole corresponding to the chimney, witha door in the side through which the fuel is put in. Thefurnace is placed upon an inverted pot, which has a holein its top answering to that in the bottom of the furnace,another large one in its side, and its mouth ground smooththat it may apply itself every where close upon the flatstone or iron plate which serves as a stand for it. Intothe side aperture of this lower pot, which is both thefoot and alh-pit of the furnace, an iron pipe is inserted,somewhat wider than the widest part of the chimney,and two or three feet long, on the end of which may befitted a wooden one of more considerable length. The wholeof this pipe may be laid horizontal, so as to reach into anadjoining apartment; or rather, if there is a conveniency,the wooden pipe may be funk perpendicularly through thefloor into a room underneath, and the horizontal iron onejoined laterally to it at the top : its use is for conveyinginto the furnace, instead of the adjacent air rarefied bythe heat, the colder and denser air at a distance ; and itseffect in animating the fire will be in proportion to thecoldness and denfeness of the air to which it reaches.

In the above construction, I have endeavoured to givethe wind furnace all the advantages it appears capable otreceiving; and to supply, with black lead pots, the windfurnace, contrived by Mr. Pott, of the academy of sci-ences at Berlin, on purpose for experiments that requirethe utmost vehemence of sire, as the vitrification of

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