VOL. XLI.] PHILOSOPHICAL TRANSACTIONS. 521 



in the third experiment ; and then tried the pressure of the atmosphere on 

 the clack or valve d, and found it required about lOlb. Troy, to lift the clack 

 from its tube of I inch diameter. 



dthly. He excluded the air with the steam, and instead of the clack he screwed 

 on very tight a plate, on which he placed a glass receiver, as usual, with the 

 air-pump; and then, turning the cock, the air under the glass receiver expanded 

 itself into the globe, by which he had equally a share of the vacuum partly 

 made in the globe, and could thereby make many experiments that are made 

 with the air-pump, &c. 



Observations from Experiments made by J, Payne. — 1. That a pot or vessel, 

 of the size and shape here mentioned, will (being kept to a dark-red heat, and 

 the water regularly dispersed) rarefy or expand 50 gallons of water, wine mea- 

 sure, per hour. 



1. That a cubic inch of water will make in practice 4000 inches of steam ; 

 or that the elastic steam of one cubic inch of water is sufficient to exclude the 

 air out of a vessel that is in content 4000 inches. 



3. That the above 50 gallons will produce 46,000,000 cubic inches of elastic 

 steam per hour, which is per minute 770,000. 



4. That the 2d pot or vessel, as in fig. 7, will rarefy or expand 40 gallons of 

 water, wine measure, per hour, and will produce 36,960,000 cube inches of 

 elastic steam, per hour, which is per minute 6l6,000 inches. 



5. That both, being united together, make ], 386,000 cube inches of steam 

 every minute, from 346 inches of water. 



6. That, by an experiment made by a fire-engine, 40 gallons of water per 

 hour, made into elastic steam in this method, will effectually give motion to a 

 24 inch cylinder fire-engine. 



7. That, by true experiments, made at Wedgbury and Newcastle on Tyne, 

 ll2lb. of pit-coals, will, and is sufficient in this method, to expand or rarefy 

 go gallons of water per hour into an elastic steam or vapour. 



8. That, by the best accounts and observations he could get and make, they 

 consume under their boilers, to make the same quantity of steam, 3 cwt. of 

 pit-coal, in working a fire-engine one hour. 



9. That 95 gallons of water per hour, expanded or rarefied into steam, will 

 work a 36 inch cylinder engine. 



10. From these observations Mr. P. concludes, that this new invention will 

 save at least 60 per cent, in pit-coals, to work a fire-engine. 



In fig. 6, pi. II, A, A, represent the two pots ; b, b, the two copper heads 

 or globes ; c, c, the two sink pipes, for waste water, not evaporated ; d, d, 

 clacks or valves, to keep out the air; e, e, the two dispersers and spouts; f, p, 

 the stools with a centre-pin, on which the dispersfjr rests; g, g, the two^iron 



VOL. VIII. 3 X 



