VOL. XLII.] PHILOSOPHICAL TRANSACTIONS. 563 



tive in hospital ships; where, though fresh air imperceptibly received is abso- 

 lutely necessary to preserve the crew, as free as possible, from the infectious 

 breath and exhalations of the diseased and wounded seamen, yet blasts of wind, 

 pouring impetuously into the very places where the sick lie, must be attended 

 with such consequences as are too obvious to mention. 



To remedy these inconveniencies, to prevent air proving foul even in the wells 

 and holds of ships, and to cause imperceptibly a large circulation of fresh air 

 into every part of the ship at all times, Mr. Sutton has invented the following 

 scheme, in the preceding N° of the Trans, which is useful not only in these 

 cases, but, by altering some parts, as particular places require, may be applied 

 to houses, close parts of prisons, wells at land, privies, hospitals, &c. 



Nothing rarefies air so considerably as heat, and whenever it causes a dimi- 

 nution of the density of the air, that part next in contact will rush in, and be 

 succeeded by a constant supply, till the air becomes of an equal degree of elas- 

 ticity. Therefore, if a tube be laid in the well, hold, or any other part of the 

 ship, and the upper part of this tube be sufficiently heated to rarefy the im- 

 pending column of air, the equilibrium will be maintained by the putrid air 

 from the bottom, which being drawn out this way, a supply of fresh air from 

 the other parts of the ship will succeed in its place; which operation, being 

 continued, will entirely change the air in all the parts of the ship. This prin- 

 ciple, exactly conformable to the doctrine of pneumatics, is the basis of Mr. 

 Sutton's machine, which being put in execution on board the Hulk at Deptford, 

 before the lords of the Admiralty, commissioners of the navy, the very learned 

 and ingenious president M. Folkes, Esq. Dr. Mead, &c. performed to their 

 satisfaction, in bringing air from the bread-room, horlop and well of the ship 

 at the same time, in such quantity, that large lighted candles being put to the 

 end of tubes, the flame was immediately sucked out as fast as applied, though 

 the end of one of the tubes was above 20 yards distant from the fire. The 

 method is as follows: 



To boil the provisions of the ship's company, they have a copper, larger or 

 smaller in proportion to the size of the ship, and number of the crew : this 

 copper is fixed in ships in the manner as on land, having under it two holes 

 divided by an iron grate. The first hole, having an iron door, is for the fire ; 

 the ashes from the grate drop through into the bottom of the other ; the smoke 

 passes through a chimney, and is discharged as usual. After the fire is lighted, 

 it is supported by the air from the parts next the ash-pit ; but having, contrary 

 to the usual custom, adapted an iron door, like the former, made very tight, 

 to prevent the ingress of air, the fire would soon be extinguished, if not sup- 



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