694 PHILOSOPHICAL TRANSACTIONS. [aNNO 1742. 



that, if a conveyance for air be laid from the hold or well of the ship, and a 

 rarefaction of the air therein be made ; the foul air from this place will run or 

 be drawn out that way, and fresh air from the adjacent parts will succeed in its 

 room. 



ft is on these principles that the following scheme was offered to the 

 Lords of the Admiralty, and Commissioners of the Navy. And the means 

 to be employed are shortly the following : that whereas in every ship, of any 

 bulk, there is already provided a copper or boiling-place, proportionable to the 

 size of the vessel, it is proposed to clear the bad air by means of the fire used 

 under the said coppers or boiling places, for the necessary uses of the ship. — 

 Under every such copper or boiler, there are 1 holes, separated by a grate ; 

 the first of which is for the fire, and the other for the ashes falling from it ; and 

 there is also a flue from the fire-place upwards, by which the smoke of the fire 

 is discharged at some convenient place of the ship. Now the fire once lighted 

 in these fire-places, is only preserved by the constant draught of air through 

 these 1 holes and flue ; but when the said 2 holes are closely stopped up, the 

 fire, though burning ever so briskly before, is immediately put out. 



But if, after the shutting up the abovementioned holes, another hole be 

 opened, communicating with any other room or airy place, and with the fire ; 

 it is clear, that the fire must again be raised and burn as before ; there being a 

 like draught of air through the same, as there was before the stopping up of 

 the first holes : this case differing only from the former in this, that the air 

 feeding the fire will now be supplied from another place. ~^ 



It is therefore proposed, in order to clear the holds of ships of the bad air, 

 that the 2 holes abovementioned, that is, the fire-place and ash-place, be 

 both closed up with substantial and tight iron doors ; and that a copper or 

 leaden pipe, of sufficient size, be laid from the hold into the ash-place, for the 

 draught of air to come in that way to feed the fire. And thus it seems plain 

 that there will be from the hold a constant discharge of the contained air ; and 

 consequently, that the air so discharged must be as constantly supplied by fresh 

 air down the hatches, or such other communications as are open into the hold ; 

 by which the same must be continually freshened, and its air rendered more 

 wholesome, and fit for respiration. 



And if into this principal pipe so laid into the hold, other pipes are let in, 

 communicating respectively either with the well or lower decks, it must follow, 

 that part of the air consumed in feeding the fire, must be respectively drawa 

 out of all such places, to which the communication shall be so made. 



