[ *9 ] 
continue a Draught of Air from one Day to the next! 
Mr. Sutton propofcs thus to circulate the Air by the 
lame and no greater Expence of Fire than is cuftom- 
arily ufed for the Neceffities of the Ship. The Ope- 
ration of the Machine will be equally ufeful in large 
as fmall Ships; for the greater the Number of People 
they have on board, the larger Quantity, and longer 
Continuance, of the Fite will be necelfary to drefs 
the Provifion ; and therefore there will be required a 
greater Quantity of Air to fupport that Fire. The 
Size and Number of the Tubes need not be fpecified, 
becaufe as the Confumption of Air is in proportion 
to the Quantity of Fire, the wider the Tube, and 
greater the Number, the lefs the Velocity of the Air, 
and vice verfa. 
I feveral times obferved in this Machine, when for 
the fake of Obfervation, after the Fire was well 
lighted, and the lowed iron Door left open, that the 
Flame did not afeend fo high, or burn fo fierce } but 
immediately upon {hutting thereof, when the Draught 
of Air was only through the Tubes, the Flame foon 
recovered its former Vigour. - L 
There is likewife, efpecially in large Ships, not 
only a Copper, but alfo a Fire-grate like thole ufed 
in Kitchens : That the Heat and Smoke of this alfo 
may not be ufelefs, an iron Tube may be fixed behind 
the Grate, and inferred quite through the Brick- work, 
and through the Deck, fo that one End thereof will 
ftand about a Foot, or little more, in the Chimney 
above the Brick- work, and the other will enter into 
the Hold, or any other Part of the Ship ; fo that the 
upper End being heated, the Draught of Air will be 
fupplied from below, as in the other Cafe. This 
like- 
