« AnteriorContinuar »
a house are necessarily of different heights or nel diminished. In the larger opening, billengths, that from the lowest floor being the lets of two feet long, or half the common highest or longest, and those of the other length of cordwood, may be burnt convenientfloors shorter and shorter, till we come to ly; and for the smaller, such wood may be those in the garrets, which are of course the sawed into thirds. Where coals are the fuel, shortest : and the force of draft being, as al- the grates will be proportioned to the openready said, in proportion to the height of fun- ings. The same depth is nearly necessary to nel filled with rarefied air; and a current of all, the funnels being all made of a size proper air from the room into the chimney, sufficient to admit a chimney-sweeper. If in large to fill the opening, being necessary to oppose and elegant rooms custom or fancy should reand prevent the smoke coming out into the quire the appearance of a large chimney, it room; it follows, that the openings of the may be formed of extensive marginal decoralongest funnels may be larger, and that those tions, in marble, &c. In time, perhaps, that of the shorter funnels should be smaller. For which is fittest in the nature of things may if there be a large opening to a chimney that come to be thought handsomest. But at predoes not draw strongly, the funnel may hap- sent, when men and women in different counpen to be furnished with the air it demands tries show themselves dissatisfied with the by a partial current entering on one side of the forms God has given to their heads, waists, opening, and, leaving the other side free of and feet, and pretend to shape them more any opposing current, may permit the smoke perfectly, it is hardly to be expected that to issue there into the room. Much too of they will be content always with the best the force of draft in a funnel depends on the form of a chimney. And there are some, I degree of rarefaction in the air it contains, know, so bigoted to the fancy of a large noble and that depends on the nearness to the fire opening, that rather than change it, they of its passage in entering the funnel. If it would submit to have damaged furniture, can enter far from the fire on each side, or sore eyes, and skins almost smoked to bacon. far above the fire, in a wide or high opening, 3. Another cause of smoky chimneys is, too it receives little heat in passing by the fire, short a funnel. This happens necessarily in and the contents of the funnel is by that means some cases, as where a chimney is required less different in levity from the surrounding in a low building ; for if the funnel be raised atmosphere, and its force in drawing conse- high above the roof, in order to strengthen its quently weaker. Hence if too large an open- draft, it is then in danger of being blown down, ing be given to chimneys in upper rooms, and crushing the roof in its fall. those rooms will be smoky: on the other Remedies. Contract the opening of the hand, if too small openings be given to chim-chimney, so as to oblige all the entering air neys in the lower rooms, the entering air, to pass through or very near the fire; whereoperating too directly and violently on the by it will be more heated and rarefied, the fire, and afterwards strengthening the draft funnel itself be more warmed, and its contents as it ascends the funnel, will consume the fuel have more of what may be called the force too rapidly.
of levity, so as to rise strongly and maintain Remedy. As different circumstances fre a good draft at the opening. quently mix themselves in these matters, it Or you may in some cases, to advantage, is difficult to give precise dimensions for the build additional stories over the low building openings of all chimneys. Our fathers made which will support a high funnel. them generally much too large; we have If the low building be used as a kitchen, lessened them; but they are often still of and a contraction of the opening therefore ingreater dimension than they should be, the convenient, a large one being necessary, at human eye not being easily reconciled to least when there are great dinners, for the sudden and great changes. If you suspect free management of so many cooking utenthat your chimney smokes from the too great sils; in such case I would advise the building dimension of its opening, contract it by plac. of two more funnels joining to the first, and ing moveable boards so as to lower and nar- having three moderate openings, one to each row it gradually, till you find the smoke no funnel, instead of one large one. When there longer issues into the room. The proportion is occasion to use but one, the other two may so found will be that which is proper for that be kept shut by sliding plates, hereafter to be chimney, and you may employ the bricklayer described ;* and two or all of them may be or mason to reduce it accordingly. However, used together when wanted. This will inas, in building new houses, something must deed be an expense, but not an useless one, be sometimes hazarded, I would make the since your cooks will work with more comopenings in my lower rooms about thirty fort, see better than in a smoky kitchen what inches square and eighteen deep, and those in they are about, your victuals will be cleaner the upper, only eighteen inches square and dressed, and not taste of smoke, as is often not quite so deep; the intermediate ones diminishing in proportion as the height of fun * See Notes at the end of this paper, No. II.
the case; and to render the effect more cer- always presents it back to the current. This tain, a stack of three funnels may be safely I believe may be generally effectual, though built higher above the roof than a single not certain, as there may be cases in which it funnel.
will not succeed. Raising your funnels, if The case of two short a funnel is more ge-practicable, so as their tops may be higher, or neral than would be imagined, and often at least equal with the commanding eminence, found where one would not expect it. For is more to be depended on. But the turning it is not uncommon, in ill-contrived buildings, cap, being easier and cheaper, should first be instead of having a funnel for each room or tried. If obliged to build in such a situation, fire-place, to bend and turn the funnel of an I would choose to place my doors on the side upper room so as to make it enter the side of next the hill, and the backs of my chimneys on another funnel that comes from below. By the furthest side ; for then the column of air this means the upper room funnel is made falling over the eminence, and of course short of course, since its length can only be pressing on that below, and forcing it to enter reckoned from the place where it enters the the doors, or Was-ist-dases on that side, would lower room funnel; and that funnel is also tend to balance the pressure down the chimshortened by all the distance between the en- neys, and leave the funnels more free in the trance of the second funnel and the top of the exercise of their functions. stack; for all that part being readily supplied 6. There is another case of command, the with air through the second funnel, add no reverse of that last inentioned. It where strength to the draught, especially as that air the commanding eminence is farther from the is cold where there is no fire in the second wind than the chimney commanded. To exchimney. The only easy remedy here is, to plain this a figure may be necessary. Supkeep the opening shut of that funnel in which pose then a building whose side A happens there is no fire.
to be exposed to the wind, and forms a kind 4. Another very common cause of the of dam against its progress. (Plate, figure smoking of chimneys, is, their overpowering 3.) The air obstructed by this dam will, one another. For instance, if there be two like water, press and search for passages chimneys in one large room, and you make through it; and finding the top of the chimfires in both of them, the doors and windows ney B, below the top of the dam, it will force close shut, you will find that the greater and itself down that funnel in order to get through stronger fire shall overpower the weaker, and by some door or window open on the side of draw air down its funnel to supply its own de- the building. And if there be a fire in such mand; which air descending in the weaker chimney, its smoke is of course beat down, funnel will drive down its smoke, and force it and fills the room. into the room. If, instead of being in one Remedy. I know of but one, which is to room, the two chimneys are in two different raise such funnel higher than the roof, suprooms, communicating by a door, the case is porting it, if necessary, by iron bars. For a the same whenever that door is open. In a turn-cap in this case has no effect, the damvery tight house, I have known a kitchen med up air pressing down through it in whatchimney on the lowest floor, when it had a ever position the wind may have placed its great fire in it, overpower any other chimney opening. in the house, and draw air and smoke into its I know a city in which many houses are room, as often as the door was opened com- rendered smoky by this operation. For their municating with the staircase.
kitchens being built behind, and connected Remedy. Take care that every room has by a passage with the houses, and the tops of the means of supplying itself from without, the kitchen chimneys lower than the top of with the air its chimney may require, so that the houses, the whole side of a street, when no one of them may be obliged to borrow from the wind blows against its back, forms such a another, nor under the necessity of lending. dam as above described; and the wind, so ob A variety of these means have been already structed, forces down those kitchen chimneys described.
(especially when they have but weak fires in 5. Another cause of smoking is, when the them) to pass through the passage and house tops of chimneys are commanded by higher into the street. Kitchen chimneys, so formbuildings, or by a hill, so that the wind blow- ed and situated, have another inconvenience. ing over such eminences falls like water over In summer, if you open your upper room a dam, sometimes almost perpendicularly on windows for air, a light breeze blowing over the tops of the chimneys that lie in its way, your kitchen chimney towards the house, and beats down the smoke contained in them. though not strong enough to force down its
Remedy. That commonly applied to this smoke as aforesaid, is sufficient to waft it into case, is a turncap made of tin or plate iron, co- your windows, and fill the rooms with it; vering the chimney above and on three sides, which, besides the disagreeableness, damages open on one side, turning on a spindle, and your furniture. which, being guided or governed by a vane, 7. Chimneys, otherwise drawing well, are
sit in its way:
sometimes made to smoke by the improper | when it begins to hesitate; and as the heat and inconvenient situation of a door. When of the day approaches, it sets downwards, and the door and chimney are on the same side of continues so till towards evening, when it the room as in the figure, if the door A, be- again hesitates for some time, and then goes ing in the corner, is made to open against the upwards constantly during the night, as bewall (Plate, figure 4) which is common, as fore mentioned. Now when smoke issuing being there, when open, more out of the way, from the tops of neighbouring funnels passes it follows, that when the door is only opened over the tops of funnels which are at the time in part, a current of air rushing in passes drawing downwards, as they often are in the along the wall into and across the opening of middle part of the day, such smoke is of nethe chimney B, and flirts some of the smoke cessity drawn into these funnels, and descends out into the room. This happens more cer- with the air into the chamber. tainly when the door is shutting, for then The remedy is to have a sliding plate, herethe force of the current is augmented, and after described, * that will shut perfectly the becomes very inconvenient to those who, offending funnel. warming themselves by the fire, happen to 9. Chimneys which generally draw well,
do nevertheless sometimes give smoke into The remedies are obvious and easy. Either the rooms, it being driven down by strong put an intervening skreen from the wall winds passing over the tops of their funnels, round great part of the fire-place; or, which though not descending from any commanding is perhaps preferable, shift the hinges of your eminence. This case is most frequent where door, so as it may open the other way, and the funnel is short, and the opening turned when open throw the air along the other wall. from the wind. It is the more grievous, when
8. A room, that has no fire in its chimney, it happens to be a cold wind that produces the is sometimes filled with smoke which is re- effect, because when you most want your fire, ceived at the top of its funnel and descends you are sometimes obliged to extinguish it. into the room. In a former paper* I have al. To understand this, it may be considered,
that ready explained the descending currents of the rising light air, to obtain a free issue from air in cold funnels; it may not be amiss how the funnel, must push out of its way or oblige ever to repeat here, that funnels without fires the air that is over it to rise. In a time of have an effect, according to their degree of calm or of little wind this is done visibly, for coldness or warmth, on the air that happens we see the smoke that is brought up by that to be contained in them. The surrounding air rise in a column above the chimney. But atmosphere is frequently changing its tem- when a violent current of air, that is, a strong perature; but stacks of funnels, covered from wind, passes over the top of a chimney, its winds and sun by the house that contains particles have received so much force, which them, retain a more equal temperature. If, keeps them in a horizontal direction and follow after a warm season, the outward air sudden- each other so rapidly, that the rising light air ly grows cold, the empty warm funnels begin has not strength sufficient to oblige them to to draw strongly upward ; that is, they rarefy quit that direction and move upwards to perthe air contained in them, which of course mit its issue. Add to this, that some of the rises, cooler air enters below to supply its current passing over that side of the funnel place, is rarefied in its turn and rises ; and which it first meets with, viz. at A, (Plate, this operation continues till the funnel grows figure 5.) having been compressed by the recooler, or the outward air warmer, or both, sistance of the funnel, may expand itself over when the motion ceases. On the other hand, the flue, and strike the interior opposite side if after a cold season, the outward air sudden- at B, from whence it may be reflected downly grows warm and of course lighter, the air wards and from side to side in the direction of contained in the cool funnels, being heavier, the pricked lines C C C.. descends into the room; and the warmer air
Reniedies. In some places, particularly in which enters their tops being cooled in its Venice, where they have not stacks of chimturn, and made heavier, continues to descend; neys but single flues, the custom is, to open and this operation goes on till the funnels are or widen the top of the flue rounding in the warmed by the passing of warm air through true form of a funnel; (Plate, figure 6) which them, or the air itself grows cooler. When some think may prevent the effect just menthe temperature of the air and of the funnels tioned, for that the wind blowing over one of is nearly equal, the difference of warmth in the edges into the funnel may be slanted out the air between day and night is sufficient to again on the other side by its form. I have had produce these currents, the air will begin to no experience of this, but I have lived in a ascend the funnels as the cool of the evening windy country, where the contrary is practised, comes on, and this current will continue till the tops of the flues being narrowed inwards, perhaps nine or ten o'clock the next morning, so as to form a slit for the issue of the smoke,
* See Notes at the end of this paper, No. II.
* See Notes at the end of this paper, No. II.
long as the breadth of the funnel, and only four | don have got over that objection, and now inches wide. This seems to have been contriv- think it rather contributes to render their air ed on a supposition, that the entry of the wind salubrious, as they have had no general pestiwould thereby be obstructed, and perhaps it lential disorder since the general use of coals, might have been imagined, that the whole when, before it, such were frequent. Paris force of the rising warm air being condensed, still burns wood at an enormous expense, conas it were, in the narrow opening, would tinually augmenting, the inhabitants having thereby be strengthened, so as to overcome still that prejudice to overcome. In Germany the resistance of the wind. This however you are happy in the use of stoves, which save did not always succeed; for when the wind fuel wonderfully: your people are very inwas at north-east and blew fresh, the smoke genious in the management of fire ; but they was forced down by fits into the room I com- may still learn something in that art from the monly sat in, so as to oblige me to shift the Chinese,* whose country being greatly popufire into another. The position of the slit of lous and fully cultivated, has little room left this funnel was indeed north-east and south. for the growth of wood, and having not much west. Perhaps if it had lain across the wind, other fuel that is good, have been forced upon the effect might have been different. But on many inventions during a course of ages, for this I can give no certainty. It seems a mat- making a little fire go as far as possible. ter proper to be referred to experiment. Pos I have thus gone through all the common sibly a turn-cap might have been serviceable, causes of the smoking of chimneys that I can but it was not tried.
at present recollect as having fallen under my Chimneys have not been long in use in observation; communicating the remedies England. I formerly saw a book printed in that I have known successfully used for the the time of queen Elizabeth, which remarked different cases, together with the principles the then modern improvements of living, and on which both the disease and the remedy de mentioned among others the convenience of pend, and confessing my ignorance wherever I chimneys. “Our forefathers," said the au- have been sensible of it. You will do well, if thor," had no chimneys. There was in each you publish, as you propose, this letter, to add dwelling house only one place for a fire, and in notes, or as you please, such observations the smoke went out through a hole in the as may have occurred to your attentive mind; roof; but now there is scarce a gentleman's and if other philosophers will do the same, house in England that has not at least one this part of science, though humble, yet of chimney in it.”-When there was but one great utility, may in time be perfected. For chimney, its top might then be opened as a fun- many years past, I have rarely met with a nel, and perhaps, borrowing the form from the case of a smoky chimney, which has not been Venetians, it was then the flue of a chimney solvable on these principles, and cured by got that name. Such is now the growth of these remedies, where people have been will. luxury, that in both England and France we ing to apply them ; which is indeed not almust have a chimney for every room, and in ways the case; for many have prejudices in some houses every possessor of a chamber, favour of the nostrums of pretending chimney and almost every servant, will have a fire; doctors and fumists, and some have conceits so that the flues being necessarily built in and fancies of their own, which they rather stacks, the opening of each as a funnel is im- choose to try, than to lengthen a funnel, alter practicable. This change of manners soon the size of an opening, or admit air into a consumed the firewood of England, and will room, however necessary; for some are as soon render fuel extremely scarce and dear in much afraid of fresh air as persons in the hyFrance, if the use of coals be not introduced drophobia are of fresh water. I myself had in the latter kingdom, as it has been in the formerly this prejudice, this aerophobia, as I former, where it at first met with opposition; now account it, and dreading the supposed for there is extant in the records of one of dangerous effects of cool air, I considered it queen Elizabeth's parliaments, a motion made as an enemy, and closed with extreme care by a member, reciting, " That many dyers, every crevice in the rooms I inhabited. Exbrewers, smiths, and other artificers of Lon-perience has convinced me of my error. don, had ot' late taken to the use of pitcoal for now look upon fresh air as a friend : I even their fires, instead of wood, which filled the sleep with an open window. I am persuaded air with noxious vapours and smoke, very that no common air from without is so unprejudicial to the health, particularly of per- wholesome as the air within a close room that sons coming out of the country; and therefore has been often breathed and not changed. moving that a law might pass to prohibit the Moist air too, which formerly I thought peruse of such fuel (at least during the session nicious, gives me now no apprehensions: for of parliament) by those artificers.”—It seems considering that no dampness of air applied to it was not then commonly used in private the outside of my skin can be equal to what houses. Its supposed unwholesomeness was an objection. Luckily the inhabitants of Lon
* See Notes at the end of this paper, No. II.
is applied to and touches it within, my whole some of the rooms so contrived as to communibody being full of moisture, and finding that cate on occasion with others, so as to form difI can lie two hours in a bath twice a week, ferent combinations, and exemplify different covered with water, which certainly is much cases; with quantities of green wax taper damper than any air can be, and this for cut into pieces of an inch and half, sixteen of years together, without catching cold, or be which stuck together in a square, and lit, ing in any other manner disordered by it, I would make a strong fire for a little glass no longer dread mere moisture, either in air chimney, and blown out would continue to or in sheets or shirts : and I find it of impor. burn and give smoke as long as desired. tance to the happiness of life, the being freed With such an apparatus all the operations of from vain terrors, especially of objects that smoke and rarefied air in rooms and chimneys we are every day exposed inevitably to meet might be seen through their transparent with. You physicians have of late happily sides; and the effect of wind on chimneys, discovered, after a contrary opinion had pre- commanded or otherwise, might be shown by vailed some ages, that fresh and cool air does letting the entering air blow upon them good to persons in the small pox and other through an opened window of the lecturer's fevers. It is to be hoped, that in another chamber, where it would be constant while century or two we may all find out, that it is he kept a good fire in his chimney. By the not bad even for people in health. And as to help of such lectures our fumists would be moist air, here I am at this present writing come better instructed. At present they in a ship with above forty persons, who have have generally but one remedy, which per+ had no other but moist air to breathe for six haps they have known effectual in some one weeks past; every thing we touch is damp, case of smoky chimneys, and they apply that and nothing dries, yet we are all as healthy indiscriminately to all the other causes, withas we should be on the mountains of Switz-out success,—but not without expense to their erland, whose inhabitants are not more so than employers. those of Bermuda or St. Helena, islands on With all the science, however, that a man whose rocks the waves are dashed into mil- shall suppose himself possessed of in this arlions of particles, which fill the air with damp, ticle, he may sometimes meet with cases that but produce no diseases, the moisture being may puzzle him. I once lodged in a house pure, unmixed with the poisonous vapours at London, which, in a little room, had a sinarising from putrid marshes and stagnant gle chimney and funnel. The opening was pools, in which many insects die and corrupt very small, yet it did not keep in the smoke, the water. These places only, in my opinion and all attempts to have a fire in this room (which however I submit to yours) afford were fruitless. I could not imagine the reaunwholesome air; and that it is not the mere son, till at length observing that the chamber water contained in damp air, but the volatile over it, which had no fire-place in it, was alparticles of corrupted animal matter mixed ways filled with smoke when a fire was kinwith that water, which renders such air per- dled below, and that the smoke came through nicious to those who breathe it. And I ima- the cracks and crevices of the wainscot; I had
gine it a cause of the same kind that renders the wainscot taken down, and discovered that | the air in close rooms, where the perspirable the funnel which went up behind it, had a
matter is breathed over and over again by a crack many feet in length, and wide enough
number of assembled people, so hurtful to to admit my arm, a breach very dangerous | health. After being in such a situation, ma- with regard to fire, and occasioned probably
ny find themselves affected by that febricula, by an apparent irregular settling of one side which the English alone call a cold, and per- of the house. The air entering this breach haps from the name, imagine that they caught freely, destroyed the drawing force of the the malady by going out of the room, when funnel. The remedy would have been, filling it was in fact by being in it.
up the breach or rather rebuilding the funnel : You begin to think that I wander from my but the landlord rather chose to stop up the subject, and go out of my depth. So I return chimney. again to my chimneys.
Another puzzling case I met with at a We have of late many lectures in experi- friend's country house near London. His mental philosophy. I have wished that some best room had a chimney in which, he told of them would study this branch of that sci- me, he never could have a fire, for all the ence, and give experiments in it as a part of smoke came out into the room. I flattered their lectures. The addition to their present myself I could easily find the cause, and preapparatus need not be very expensive. A num- scribe the cure. I had a fire made there, ber of little representations of rooms composed and found it as he said. I opened the door, each of five panes of sash glass, framed in wood and perceived it was not want of air. I at the corners, with proportionable doors, and made a temporary contraction of the opening moveable glass chimneys, with openings of dif- of the chimney, and found that it was not its ferent sizes, and different lengths of funnel, and being too large that caused the smoke to VOL. II. ...3 F