Fireplace

"By the throat of a Chimney, I mean the lower extremity of its canal, where it unites with the upper part of its open Fire-place.—This throat is commonly found about a foot above the level of the lower part of the mantle, and it is sometimes contracted to a smaller size than the rest of the canal of the Chimney, and sometimes not."

"The breast of a Chimney is that part of it which is immediately behind the mantle.—It is the wall which forms the entrance from below into the throat of the Chimney in front, or towards the room. — It is opposite to the upper extremity of the back of the open Fire-place, and parallel to it;—in short it may be said to be the back part of the mantle itself."

"The width of the throat of Chimney... is taken from the breast of the Chimney to the back, and its length is taken at right angles to its width, or in a line parallel to the mantle..."

"The bringing forward of the fire into the room, or rather bringing it nearer to the front of the opening of the Fire-place;—and the diminishing of the throat of the Chimney, being two objects principally had in view in the alterations... here recommended... both... may be attained merely by bringing forward the back of the chimney."

"The only question... is, how far [the fire] should be brought forward?—The answer... bring it forward as far as possible, without diminishing too much the passage which must be left for the smoke."

"Now as this passage, which, in its narrowest part, I have called the throat of the Chimney, ought... to be immediately, or perpendicularly over the Fire, it is evident that the back of the Chimney must always be built perfectly upright.—To determine therefore the place for the new back, or how far precisely it ought to be brought forward, nothing more is necessary that to ascertain how wide the throat of the Chimney to be left, or what trace must be left between the top of the breast of the Chimney, where the upright canal of the Chimney begins, and the new back of the Fire-place carried up perpendicularly to that height."

"In the course of my numerous experiments upon Chimnies I have taken much pains to determine the width proper to be given to this passage, and I have found that, when the back of the Fire-place is of the proper width, the best width for the throat of the Chimney, when the Chimney and the Fire-place are of the usual form and size, is four inches. Three inches might sometime answer, especially where the Fire-place is very small, and the Chimney good, and well situated; but as it is... of much importance to prevent those accidents... putting too many coals at once upon the fire... when the throats of Chimnies were... very narrow..."

"It may... appear extraordinary... that Fire-places of such different sizes should all require the throat of the Chimney to be of the same width; but... the capacity of the throat of a Chimney does not depend on its width alone, but on its width and length taken together; and that in large Fire-places, the width of the back, and consequently the length of the throat of the Chimney, is greater than in those which are smaller..."

"In Fire-places as they are now commonly constructed, the back is of equal width with the opening of the Fire-place in front;-—but this... is faulty on two accounts.— First... the sides... or covings... are parallel to each other, and consequently ill-contrived to throw out into the room the heat they receive from the fire in the form of rays;—and secondly, the large open corners which are formed by making the back as wide as the opening of the Fire-place in front occasion eddies of wind, which frequently disturb the fire, and embarrass the smoke in its ascent in such a manner as often to bring it into the room."

"Both these defects may be entirely remedied by diminishing the width of the back of the Fire-place.—The width which, in most cases, it will be best to give it, is one third of the width of the opening of the Fire-place in front."

"It will frequently happen that the back of a Chimney must be made wider than... the rule here given... This may be, either to accommodate the Fire-place to a stove... already on hand... or for other reasons... with no considerable inconvenience.—It will always be best however to conform to it as far as circumstances will allow."

"Where a Chimney is designed for warming a room of a middling size, and where the thickness of the wall of the Chimney in front, measured from the front of the mantle to the breast of the Chimney, is nine inches, I should set off four inches more for the width of the throat of the Chimney, which supposing the back of the Chimney to be built upright, as it always ought to be, will give thirteen inches for the depth of the Flre-place measured upon the hearth, from the opening of the Fire-place in front, to the back.—In this case thirteen inches would be a good size for the width of the back; and three times thirteen inches, or thirty-nine inches, for the width of the opening of the Fire-place in front; and the angle made by the back of the Fire-place and the sides of it, or covings, would be just 135 degrees, which is the best position they can have for throwing heat into the room."

"I will suppose that in altering such a Chimney it is found necessary, in order to accommodate the Fire-place to a grate or stove already on hand, to make the Fire-place sixteen inches wide.—In that case, I should merely increase the width, of the back, to the dimensions required, without; altering the depth of the Chimney, or increasing the width of the opening of the Chimney in front.—The covings... would be somewhat reduced in their width... and their position... would be a little changed; but these alterations would produce no bad effects of any considerable consequence, and would be much less likely to injure the Fire-place..."

"Should the opening of the Chimney be too narrow, which however will very seldom be found to be the case, it will, in general, be advisable to let it remain as it is, and to accommodate the covings to it, rather than to attempt to increase its width, which would be attended with a good deal of trouble, and probably a considerable expence."

"[T]he points of the greatest importance... in altering Fire-places upon the principles here recommended, are, the bringing forward the back to its proper place, and making it of a proper width."

"[T]he new back... necessary to build in order to bring the fire sufficiently forward... need never be thicker than the width of a common brick.—I may say the same of the thickness necessary to be given to the new sides, or covings... or if the new back and covings are constructed of stone, one inch and three quarters, or two inches in thickness will be sufficient."

"Whether the new back and covings are constructed of stone, or... bricks, the space between them, and the old back and covings of the Chimney ought to be filled up... with loose rubbish, or pieces of broken bricks, or stones, provided the work be strengthened by a few layers or courses of bricks laid in mortar; but it will be indispensably necessary to finish the work where these new walls end... at the top of the throat of the Chimney, where it ends abruptly in the open canal of the Chimney by a horizontal course of bricks well secured with mortar."

"[W]here the throat of the Chimney has an end... where it enters into the lower part of the open canal of the Chimney, there the three walls which form the two covings and the back of the Fire-place all end abruptly. ...[T]hey should end in this manner for were they to be sloped outward and raised in such a manner as to swell out the upper extremity of the throat of the Chimney in the form of a trumpet, and increase it by degrees to the size of the canal of the Chimney, this manner of uniting the lower extremity of the canal of the Chimney with the throat would tend to assist the winds which may attempt to blow down the Chimney, in forcing their way through the throat, and throwing the smoke backward into the room; but when the throat of the Chimney ends abruptly, and the ends of the new walls form a flat horizontal surface, it will be much more difficult for any wind from above, to find, and force its way, through the narrow passage of the throat..."

"As the two walls which form the new covings... are not parallel... but inclined, presenting an oblique surface towards the front of the Chimney, and as they are built perfectly upright, and quite flat, from the hearth to the top of the throat, where they end... an horizontal section of the throat will not be an oblong square; but its deviation from that form is a matter of no consequence; and no attempts should ever be made, by twisting the covings above, where they approach the breast of the Chimney, to bring it to that form."

"All twists, bends, prominences, excavations, and other irregularities of form, in the covings... never fail to produce eddies in the current of air which is continually passing into, and through an open Fire-place in which a fire is burning;—and all such eddies disturb, either the fire, or the ascending current of smoke, or both; and not unfrequently cause the smoke to be thrown back into the room.—Hence... the covings... should never be made circular, or in the form of any other curve; but always quite flat."

"For the same reason, that is... to prevent eddies, the breast of the Chimney, which forms [the front] side of the throat... or nearest to the room, should be neatly cleaned off, and its surface made quite regular and smooth. This may easily be done by covering it with a coat of plaister, which may be made thicker or thinner in different parts as may be necessary in order to bring the breast of the Chimney to be of the proper form."

"[T]he form of the breast of the Chimney is... of... great importance... The worst form it can have is that of a vertical plane, or upright flat;—and next... worst... is an inclined plane.—Both... cause the current of warm air from the room, which will... sometimes find its way into the Chimney, to cross upon the current of smoke, which rises from the fire, in a manner, most likely to embarrass it in its ascent, and drive it back.— The inclined plane which is formed by a flat register placed in the throat of a Chimney produces the same effects; and this is one reason, among many... which have induced me to disapprove of register stoves."

"The current of air, which, passing under the mantle, gets into the Chimney, should be made gradually to bend its course upwards, by which means it will unite quietly with the ascending current of smoke, and will be less likely to check it, or force it back into the room.—Now this may be effected with the greatest ease and certainty, merely by rounding off the breast of the Chimney or back part of the mantle, instead of leaving it flat, or full of holes and corners; and this... ought always to be done."

"[T]he height to which the new back and covings ought to be carried... will depend not only on the height of the mantle, but also, and more especially, on the height of the breast of the Chimney, or of that part of the Chimney where the breast ends and the upright canal begins.—The back and covings must rise a few inches, five or six... higher than this part, otherwise the throat of the Chimney will not be properly formed;—but I know of no advantages that would be gained by carrying them up still higher."

"Those [grates] whose construction is the most simple, and... the cheapest, are beyond comparison the best, on all accounts.— Nothing being wanted in these Chimnies but merely a grate for containing the coal, and in which they will burn with a clear fire;—and all additional apparatus being, not only useless, but very pernicious, all complicated and expensive grates should be laid aside, and such as are more simple substituted in the room of them."

"And in the choice of a grate, as in every thing else, beauty and elegance may easily be united with the most perfect simplicity.—Indeed they are incompatible with every thing else."

"In modern built houses where the doors and windows are... made to close with such accuracy that no crevice is left for the passage of the air from without... When there is a fire burning... as the air necessary to supply the current up the Chimney where the fire burns cannot be had in sufficient quantities... through the very small crevices of the doors and windows, the air in the room becomes rarefied, not by heat, but by subtraction of that portion of air which is employed in keeping up the fire, or supporting the combustion of the fuel, and in consequence of this rarefaction, its elasticity is diminished, and being at last overcome by the pressure of the external air of the atmosphere, this external air rushes into the room by the only passage left for it... by the open Chimney."

"The most obvious remedy... is to provide for the supply of fresh air necessary for keeping up the fires by opening a passage for the external air into the room by a shorter road than down one of the Chimnies..."

"But Chimnies so circumstanced may very frequently be prevented from smoking even without opening any new passage for the external air, merely by diminishing the draught... up the Chimnies... by altering both Fire-places upon the principles recommended... in the foregoing..."

"Where the top of a Chimney is commanded by high buildings, by clifts, or by high grounds, it will frequently happen, in windy weather, that the eddies formed in the atmosphere by these obstacles will blow down the Chimney, and beat down the Smoke into the room.—This it is true will be much less likely to happen when the throat of the Chimney is contracted and properly formed than when it is left quite open, and the Fire-place badly constructed; but... One of the most simple contrivances that can be made use of, and which in most cases will be found to answer the purpose intended as well or better than more complicated machinery, is to cover the top of the Chimney with a hollow truncated pyramid or cone, the diameter of which above, or opening for the passage of the Smoke, is about 10 or 11 inches. ...[I]ts perpendicular height may be equal to the diameter of its opening above, and the diameter of its opening below equal to three times its height.-—It should be placed upon the top of the Chimney, and it may be contrived so as to make a handsome finish to the brickwork."

"The intention of this contrivance is that the winds and eddies which strike against the oblique surface of these covers may be reflected upwards instead of blowing down the Chimney.—The invention is by no means new, but it has not hitherto been often put in practice.—As often as I have seen it tried it has been found to be of use; I cannot say,. however, that I was ever obliged to have recourse to it, or to any similar contrivance; and if I forbear to enlarge upon the subject of these inventions, it is because I am persuaded that when Chimnies are properly constructed in the neighbourhood of the Fire-place little more will be necessary to be done at the top of the Chimney than to leave it open."

"In lighting a coal fire more wood should be employed than is commonly used, and fewer coals; and as soon as the fire burns bright, and the coals are well lighted, and not before, more coals should be added to increase the fire to its proper size."

"The enormous waste of fuel in London may be estimated by the vast dark cloud which continually hangs over this great metropolis, and frequently overshadows the whole country, far and wide; for this dense cloud is certainly composed almost entirely of unconsumed coal, which having stolen wings from the innumerable fires of this great city has escaped by the Chimnies, and continues to sail about in the air, till having lost the heat which gave it volatility, it falls in a dry shower of extremely fine black dust to the ground, obscuring the atmosphere in its descent, and frequently changing the brightest day into more than Egyptian darkness."

"I never view from a distance, as I come into town this black cloud which hangs over London without wishing to be able to compute the immense number of chaldrons of coals of which it is composed; for could this be ascertained, I am persuaded so striking a fact would awaken the curiosity, and excite the astonishment of all ranks of the inhabitants; and perhaps turn their minds to an object of economy to which they have hitherto paid little attention."

"Though the saving of fuel which will result from the improvements to the forms of Chimney Fire-places here recommended will be very considerable, yet I hope to be able to show in a future Essay, that still greater savings may be made, and more important advantages derived from the introduction of improvements I shall propose in Kitchen Fire-places."

"I hope likewise to be able to show in an Essay on Cottage Fire-places, which I am now preparing for publication, that three quarters, at least, of the fuel which cottagers now consume in cooking their victuals, and in warming their dwellings, may with great ease, and without any expensive apparatus, be saved."

"I was much flattered on my return to England, in September 1798... to find that the improvements in the construction of chimney fire-places, which I had recommended in my Fourth Essay, published... 1796, were coming into use... It has been objected... that they sometimes occasion dust and ashes to come into the room when the fire is stirred. I have examined several fire-places... that have... that fault; but... found... their imperfections have arisen from faults in... construction. Either the grate has been brought out too far into the room, or the opening of the fire-place in front has been left too wide—or too high—or the workman has neglected to lower and to round off the breast of the chimney—or... several of these faults... together..."

"When the throat of a chimney is situated very high up above the mantle, and especially when the mantle and breast of the chimney, or the wall that reposes on the mantle, are very thin, workmen who are employed to alter chimnies, setting about the work with their minds strongly prepossessed with what they consider as the leading principle... that the throat of the chimney should not be more than four inches wide, they are very apt to bring the grate too far forward. In dropping their plumb-line from the breast of the chimney, they do not reach up high enough into the chimney, but take a part of the breast, where it still goes on to slope backwards, for the bottom of the perpendicular canal of the chimney. They also very often commit another fault, not less essential... in neglecting to bring down the throat of the chimney nearer to the fire, when... too high."

"It is likewise very important to "round off the breast of the chimney;" though this... is very often intirely neglected... by workmen..."

"The breast of a chimney should always be rounded off... beginning from the very front of the lower part of the mantle, and ending at the narrowest part of the throat of the chimney, where the breast ends in the front part of the perpendicular canal of the chimney. If the under surface of the mantle is flat and wide, it will be impossible to round off the breast properly; and that circumstance alone renders it indispensably necessary, in those cases, to alter the mantle, or to run under it a thinner piece of stone, or a thin wall of bricks, supported on an iron bar, in order that the breast of the chimney may be brought to be of the proper form, and the throat of the chimney may be brought into its proper situation."

"If the under side of the mantle be left broad and flat... the cloud of dust or light ashes, that rises from a coal fire nearly burnt out, when... violently stirred... with a poker, striking perpendicularly against this flat part... must... be beat back into the room; but when the breast of the chimney is properly rounded off, the ascending cloud of dust and smoke more easily finds its way into the throat of the chimney, and is even directed and assisted in some measure by the warm air of the room that gets under the mantle and is going the same way."

"Another very common fault... in chimney fire-places, that have been altered on what have been called my principles, and which has a direct tendency to bring dust, and even smoke, into the room, is the sloping of the covings too much, and leaving the opening of the fire-place in front too wide. I have said, in my Essay on Chimney Fire-places, that where chimnies are well constructed, and well situated, and have never been apt to smoke, in altering them the covings may be placed at an angle of 135 degrees with the back; but... that they should never exceed that angle, and... bad consequences... must follow from making the opening of a fire-place very wide, when its depth is very shallow..."

"...for chimnies that are apt to smoke, the covings should be placed less obliquely in respect to the back, than in others that have not that fault. But most... workmen... paid little attention to these distinctions and... frequently... and sometimes in fire-places that have been remarkably shallow... the covings have been placed at an angle even more oblique than that above-mentioned."

"Another cause... in bringing dust and smoke into rooms... is the great nicety with which the doors and windows are fitted in their frames, which prevents a sufficient quantity of fresh air from coming into the room, to supply a brisk current up the chimney. ...[A]ll the alterations in fire-places on the common construction, that have been recommended in order to improve them, must tend directly and very powerfully to lessen this evil; but nothing will so completely remedy it as lowering the mantle, and diminishing the width of the fire-place."

"How many fire-places in close rooms have been cured completely of throwing puffs of smoke and dust into the room, merely by placing a register-stove in them? But there is surely nothing peculiar to a register-stove that could enable it to perform such a cure, but merely as it serves to diminish the width and heighth of the opening of the fire-place; and how much easier could this be done with marble, or other stone, or with bricks and mortar... [T]he openings of chimney fire-places are in general certainly too wide and too high and... there is no way of reducing them to a proper size... so cheap, or more effectual..."

"[C]ovings of... fire-places must be placed obliquely, and they must not be constructed of metal; and if the sides and back of the grate be constructed of fire bricks instead of iron, the fire will burn still brighter, and will fend off considerably more radiant heat into the room."

"If in constructing or altering chimney fire-places, the rules laid down in my Essay on that subject are stricty adhered to, chimnies so fitted up will very seldom be found either to smoke, or to throw out dust into the room; and should they be found to have either of these faults, there is a remedy for the evil, as effectual, as it is simple and obvious: Bring down the mantle, and the throat of the chimney lower; and if it should be found necessary, reduce the width of opening of the fire-place in fronts and diminish the obliquity of the covings."

"I am not the inventor of any of those stoves or grates, that have been offered to the public for sale, under my name."

"In building a house an air canal, about twelve or fifteen inches square, in the clear, and open at both ends, may be constructed, in, or near the center of each stack of chimneys; and two branches from this air canal, both furnished with registers, may open... one... into the fire-place, just under the grate, and the other over the fire-place, and near the top of the room, or just under the ceiling... The bottom of this air tube should reach to the ground, where it should communicate freely with the open air of the atmosphere..."

"Those who consider what an immense quantity of air is required to supply the current that sets up the chimney of an open fire place, where there is a fire burning, must perceive what an enormous loss of heat there must be, when all this expence of air is supplied by the warmed air of the room, and that all this warmed air is necessarily and constantly replaced by the cold air from without, which finds its way into the room, by the crevices of the doors and windows. But all this waste of heat, or any part... may be prevented by the scheme proposed, for if the air necessary to the combustion of the fuel, and to the supplying of the current up the chimney, be furnished by the air-tube, the warmed air in the room will remain in its places and as this will in a great measure prevent the cold currents from the crevices of the door and windows, the heat in the room will be the more equable, and consequently the more wholesome and agreeable on that account."