property of the air which is called its elafticity or fpringiness, which makes it fo ufeful to our life. When any part of it is inclofed and kept from the communication of the outward air, it expands itself, and, in proportion to the clofenefs of the place, lofes its fpring; and if any heat or moisture comes to it, the elastic force may be quite loft and destroyed. And not only fo, but if it happens to be impregnated with noxious effluvia, either from unwholefome fubftances of any kind, or from the infectious breath of difeafed bodies; it will become quite poifonous and deadly, in a manner fuitable to the original cause.

It is propofed at prefent to find out a remedy for this evil in ships only: but by making alterations, according as particular places require, the fame may be applied to any houfes or parts of them, as prifons, the fick wards in hofpitals, &c.

Now, it is a natural confequent of the elafticity of the air, that when it is rarefied in any part, (which is most effectually done by heat), the neighbouring air will rush that way, till this part is brought to be of an equal denfity and elafticity with itfelf; and this again will be followed by the air next to it; fo 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 fucceed in its room.

It is upon these principles that the following fcheme is most humbly offered to the Right Honourable the Lords of the Admiraity, and Commiffioners of the Navy, which it is hoped will be found effectual for clearing the bad and corrupted air from the holds,

and

and other close parts of his Majesty's fhips; and thereby prove beneficial to the public, by preferving the healths of many of his Majesty's good subjects ferving on board the fame; the whole thing being indeed eafy to be executed, and what will no way incumber, or be troublesome, in any of the veffels where it shall happen to be applied: the fame being, in fhort, no more than this: that whereas, in every fhip of any bulk, there is already provided a copper or boilingplace proportionable to the fize of the veffel; it is proposed to clear the bad air by means of the fire already used under the faid coppers or boiling-places, for the neceffary uses of the ship.

It is well known, that, under every fuch copper or boiler, there are placed two holes, feparated by a grate; the first of which is for the fire, and the other for the ashes falling from the fame; and that there is alfo a flue from the fire-place upward, by which the smoke of the fire is discharged at fome convenient place of the fhip.

It is alfo well known, that the fire once lighted in thefe fire-places, is only preferved by the constant draught of air through the forementioned two holes and flue; and that if the faid two holes are closely stopped up, the fire, though burning ever fo briskly before, is immediately put out.

But if, after the fhutting up the above-mentioned holes, another hole be opened, communicating with any other room or airy place, and with the fire; it is clear, the faid fire must again be raised and burn as before; there being a like draught of air through the fame, as there was before the stopping up of the firft holes this cafe differing only from the former

in this, that the air feeding the fire, will now be fupplied from another place.

It is therefore propofed, that in order to clear the holds of fhips of the bad air therein contained, the two holes above mentioned, that is, the fire-place and afh-place, be both clofed up with fubftantial and tight iron doors; and that a copper or leaden pipe, of fufficient fize, be laid from the hold into the afhplace, for the draught of air to come in that way to feed the fire. And thus it feems plain from what has been already faid, that there will be from the hold a conftant difcharge of the air therein contained; and confequently, that that air fo difcharged must be as conftantly fupplied by fresh air down the hatches, or fuch other communications as are open into the hold whereby the fame must be continually freshened, and its air rendered more wholefome, and fit for refpiration.

And if into this principal pipe so laid into the hold, other pipes are let in, communicating refpectively either with the well or lower decks; it must follow, that part of the air confumed in feeding the fire, must be respectively drawn out of all such places, to which the communication shall be fo made.

то

то

MARTIN

FOLKES, Efq;

Prefident of the Royal Society.

SIR,

A

Cording to my promife, I have herewith fent

you my obfervations upon Mr Sutton's machine, which I drew up fome time fince, and intended to lay before the royal fociety in December laft, before I knew either that a model would be fhewn by Mr Sutton, or that Dr Mead would have prefented his account thereof. I am confcious of the disadvantages my flender performance muft appear under after the reading of one upon the fame fubject from fo celebrated a pen as Dr Mead's.

Thefe remarks were the refult of feveral times feeing the machine, when firft put in execution at Deptford. I hope it will not take up too much of the fociety's time to read my paper this evening, and

225

Some obfervations upon Mr Sutton's invention to extract the foul and ftinking air from the well and other parts of ships, with critical remarks upon the use of wind-fails, by William Watfon, F. R. S.

As

London, Dec. 4. 1741.

Read April 1. 1742.

S nothing is more conducive to the health of the human body, than the taking a sufficient quantity of wholesome air into the lungs ; fo the contrary is attended with pernicious, and often with destructive confequences.

One of the great ufes of air in infpiration is to cool the blood paffing through the lungs, where nature has provided, according to the excellent Malpighius, that the blood fhould be diftributed through a vaft number of exceedingly fine arteries, which occupy the thin veficles of the lungs; and by this means the blood is exposed to the air under a prodigiously large furface, whereby the putrefaction is prevented, which, from the alcacefcent quality of that fluid, would otherwife be fpeedily destructive.

Obfervations inform us, that contagious diftempers are more frequent in hot climates than in cold; and in closely-built cities full inhabited, than in towns : the former may, in fome measure, proceed from the too great heat of the air, not fully anfwering the above-mentioned purposes; and the latter from too

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