C«7 ] 
ufeful not only in th-efe Cafes, but, by altering fomc 
Parts, as particular Places require, may be applied to 
Houfes, clofe Parts of Prifons, Wells at Land, Privies, 
Hofpitals, &c. 
Nothing rarefies Air fo confiderably as Heat, and 
whenever it caufes a Diminution of the Denftry of 
the Air, that Part next in Contad will rufh in, and 
be fucceeded by a conftant Supply, till the Air be- 
comes of an equal Degree of Elaflicity. 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 fufficiently heated to rarefy the impending Column 
of Air, the ^/Equilibrium will be maintained by the 
putrid Air from the Bottom, which being drawn out 
this way, a Supply of frefih Air from the other Parts 
of the Ship will fucceed in its Place 5 which Opera- 
tion, being continued, will intirely change the Air in 
all the Parts of the Ship. This Principle, exadly 
conformable to the Dodrine of Pneumatics, is the 
Bafis of Mr. Sutton’s Machine, which being put in 
Execution on board the Hulk at ‘Deptford , before 
the Lords of the Admiralty, Commifltoners of the 
Navy, our very learned and ingenious Prefident 
M.Folkes,ECq-, Dr. Mead, See. performed to their Sat if- 
fadion, in bringing Air from the Bread-room, Hor- 
lop and Well of the Ship at the fame time, in fuch 
^Quantity, that large lighted Candles being put to the 
End of Tubes, the Flame was immediately fucked 
out as faft as applied, though the End of one of the 
Tubes was above Twenty Yards diftant from the Fire. 
The Method is as follows : 
To boil the Provifions of the Ship’s Company, they 
muft have -a Copper which is bigger or lels, in pro- 
I 2 portion 
