vol.. XLI.] PHILOSOPHICAL TRANSACTIONS. 5ig 



A pot or vessel made of wrought or cast iron, nearly the figure of a cone, its 

 diameter at the base being 4 feet, with holes round the edge, for nails or screws 

 to fasten a globular end of copper of about 5^ feet diameter. There is then 

 placed in the inside a small vessel, which Mr. P. calls a disperser. This vessel 

 has spouts round the sides fixed to it, and the bottom resting on a centre-pin ; 

 and in the middle of this basin is a socket, with holes near the bottom, to let 

 the water pass from above, through an iron pipe of about 7 feet long, the lower 

 end of which is placed in the socket, so as the end of the pipe will be always 

 immersed in water in the basin, to prevent the expanded fluid from returning 

 up the pipe ; and the other end of this pipe goes up through the copper-head, 

 which is inclosed very tight, but so as it may easily be moved with a circular 

 motion, in order that the water which is conveyed through this iron pipe down 

 into the disperser, may be dispersed or showered round, on the sides of the 

 red-hot pan, or ignited vessel, in a very exact manner. 



This evaporating vessel being completed, they then take 1, 2, or more of 

 these vessels, thus furnished, and place it or them in a reverberatory arch or 

 canal, for conveying the intense heat of a strong fire, the flame of which en- 

 compasses the metal pot or pots, and brings them to a red heat ; and in that 

 condition they are continually kept, while in use, with the water running from 

 a cistern or vessel, where the water is heated, through a guage-cock, down the 

 iron pipe, into the disperser, which conveys it to the sides of the ignited ves- 

 sel, when it is immediately rarefied or expanded into an elastic steam or vapour, 

 fit for application to give motion to sundry sorts of machinery, &c. 



In fig. 5, pi. 1 1, A represents a copper globe, 12 inches diameter ; b, b, two 

 brass cocks, one opposite to the other, fitted very tight ; c, a handle or bale, 

 fastened to the globe, by which it may be hung or held up ; d, a small valve 

 or clack, fitted to the upper cock, of one inch diameter. 



The whole thus fitted, weighed 12lb. 9-^ oz. avoirdupois; and, filled with 

 water, it weighed 45lb. 7 oz. from which deduct the metal, the weight of water 

 is 35lb. 13i oz. which is about 4 gallons. 



This vessel Mr. P. hung over the large vessel f, in which water was rarefied 

 into steam ; and by the pipe e, at the large cock g, which being open, as also 

 the other cocks b, b, the stream had a free passage through the globe a, by 

 which the stream excluded or forced out the air that was in the globe, and by 

 its elastic quality supplied its place ; when both cocks b, b, were suddenly shut, 

 and the globe a taken down and hung over a vessel of cold water, with the 

 lower cock b, immersed in water, and then opened under water ; on which the 

 water rushed violently into the globe till it had supplied the vacuum, when the 

 cock was again shut, and the globe, with the water, put in the scales, and then 

 found to weigh 44 lb. g oz. which take from 45 lb. 7 oz. the whole weight, as 



