Fireplace

"Much... of the force of draft in a funnel depends on the degree of rarefaction in the air it contains; and that depends on the nearness to the fire... in entering the funnel. If it can enter far from the fire on each side, or far above the fire in a [too] wide or high opening, it receives little heat in passing by the fire, and the contents of the funnel is by that means less different in levity from the surrounding atmosphere, and its force in drawing consequently weaker."

"Hence if too large an opening be given to chimneys in upper rooms, those rooms will be smoky."

"On the other hand, if too small openings be given to chimneys in the lower rooms, the entering air operating too directly and violently on the fire; and afterwards strengthening the draft as it ascends the funnel, will consume the fuel too rapidly."

"If you suspect that your chimney smokes from the too great dimension of its opening, contract it by placing moveable boards so as to lower and narrow it gradually, till you find the smoke no longer issues into the room. The proportion so found will be that which is proper... and you may employ the bricklayer or mason to reduce it accordingly."

"[I]n building new houses... I would have the openings in my lower rooms about thirty inches square and eighteen deep, and those in the upper only eighteen inches square and not quite so deep; the intermediate ones diminishing in proportion as the height of funnel diminished. ...The same depth is nearly necessary to all, the funnels being all made of a size proper to admit a chimney-sweeper."

"If in large and elegant rooms custom or fancy should require the appearance of a larger chimney, it may be formed of expensive marginal decorations, in marble, &c. In time, perhaps, that which is fittest in the nature of things may come to be thought handsomest."

"But at present, when men and women in different countries shew themselves dissatisfied with the forms God has given to their heads, waists, and feet, and pretend to shape them, more perfectly, it is hardly to be expected that they will be content always with the best form of a chimney. And there are some, I know, so bigotted to the fancy of a large noble opening, that, rather than change it, they would submit to have damaged furniture, fore eyes, and skins almost smoked to bacon."

"The plague of a smoking Chimney is proverbial; but there are many other very great defects in open Fire-places, as... commonly constructed... which, being less obvious, are seldom attended to; and there are some of them... fatal in their confequences... and... cost the lives of thousands every year... By a cause which might be so easily removed!—by a cause whose removal would tend to promote comfort and convenience in so many ways."

"There are various causes by which Chimnies may be prevented from carrying smoke; but there are none that may not easily be discovered and completely removed."

"Those who will take the trouble to consider the nature and properties of elastic s,—of air,—smoke,—and vapour,—and to examine the laws of their motions, and the necessary consequences of their being rarified by heat, would perceive that it would be as much a miracle if smoke should not rise in a Chimney, (all hindrances to its ascent being removed,) as that water should refuse to run in a syphon, or to descend in a river."

"The whole mystery, therefore, of curing smoking Chimnies is comprised in this simple direction,—find out and remove those local hindrances which forcibly prevent the smoke from following its natural tendency to go up the Chimney; or rather, to speak more accurately, which prevents its being forced up the Chimney by the pressure of the heavier air of the room."

"[T]hat cause which will... almost universally be found to operate, is one which it is always very easy to discover, and as easy to remove,—the bad construction of the Chimney in the neighbourhood of the Fire-place."

"I have never been obliged, except in one... instance, to have recourse to any other method of cure than merely reducing the Fire-place and the throat of the Chimney, or that part of it which lies immediately above the Fire-place, to a proper form, and just dimensions."

"[O]f above an hundred and fifty Fire-places which have been altered in this city, under my direction, within these last two months, there is not one which has not answered perfectly well. ...the saving of fuel, arising from these improvements of Fire-places, amounts in all cases to more than half, and in many cases to more than two thirds of the quantity formerly consumed."

"Now as the alterations in Fire-places which are necessary may be made at a very trifling expence... as no iron work, but merely a few bricks and some mortar, or a few small pieces of fire-stone, are required; the improvement in question is very important, when considered merely with a view to economy; but it should be remembered, that not only a great saving is made of fuel by the alterations proposed, but that rooms are made much more comfortable, and more salubrious;—that they may be more equally warmed, and more easily kept at any required temperature;—that all draughts of cold air from the doors and windows towards the Fire-place, which are so fatal to delicate constitutions, will be completely prevented;—that in consequence of the air being equally warm all over the room, or in all parts of it, it may be entirely changed with the greatest facility, and the room completely ventilated, when this air is become unfit for respiration, and this merely by throwing open for a moment a door opening into some passage from whence fresh air may be had, and the upper part of a window; or by opening the upper part of one window and the lower part of another."

"And as the operation of ventilating the room, even when it is done in the most complete manner, will never require the door and window to be open more than one minute; in this short time the walls of the room will not be sensibly cooled, and the fresh air which comes into the room will, in a very few minutes, be so completely warmed by these walls that the temperature of the room, though the air in it be perfectly changed, will be brought to be very nearly the same as it was before the ventilation."

"As long as any fire is kept up in the room, there is so considerable a current of air up the Chimney, notwithstanding all the reduction that can be made in the size of its throat, that the continual change of air in the room which this current occasions will, generally, be found to be quite sufficient for keeping the air in the room sweet and wholesome..."

"Those who have any doubts respecting the very great change of air or ventilation which takes place each time the door of a warm room is opened in cold weather, need only set the door... wide open for a moment, and hold two lighted candles in the door-way, one near the top of the door, and the other near the bottom... The violence with which the flame of that above will be driven outwards, and that below inwards by the two strong currents of air which, passing in opposite directions, rush in and out of the room at the same time, will [convince them] that the change of air which actually takes place must be very considerable... and these currents will be stronger, and consequently the change of air greater, in proportion as the difference is greater between the temperatures of the air within the room and of that without."

"The great fault of all the open Fire-places, or Chimnies, for burning... an open fire, now in common use, is, that they are much too large; or rather it is the throat of the Chimney or the lower part of its open canal, in the neighbourhood of the mantle, and immediately over the fire, which is too large. This opening has hitherto been left larger than otherwise it probably would have been made, in order to give a passage to the Chimney-sweeper; but I shall show... how a passage for the Chimney-sweeper may be contrived without leaving the throat of the Chimney of such enormous dimensions as to swallow up and devour all the warm air of the room, instead of merely giving a passage to the smoke and heated vapour which rise from the fire, for which last purpose alone it ought to be destined."

"I shall endeavour to write in such a manner as to be easily understood by those who are most likely to profit by the information I have to communicate, and consequently most likely to assist in bringing into general use the improvements I recommend."

"As the immoderate size of the throats of Chimnies is the great fault of their construction, it is this fault which ought always to be first attended to in every attempt which is made to improve them; for... if the opening left for the passage of the smoke is larger than is necessary for that purpose, nothing can prevent the warm air of the room from escaping through it; and whenever this happens, there is not only an unnecessary loss of heat, but the warm air which leaves the room to go up the Chimney being replaced by cold air from without, the draughts of cold air... cannot fail to be produced in the room..."

"[A]s the smoke and hot vapour which rise from a fire naturally tend upwards, the proper place for the throat of the Chimney is... perpendicularly over the fire."

"But ...how far above the burning fuel... ought [the throat] to be placed."

"As the smoke and vapour which ascend from burning fuel rise in consequence of their being rarified by heat, and made lighter than the air of the surrounding atmosphere; and as the degree of their rarefaction, and consequently their tendency to rise, is in proportion to the intensity of their heat; and... as they are hotter near the fire than at a greater distance from it, it is clear that the nearer the throat of a Chimney is to the fire, the stronger will be... its draught, and the less danger there will be of its smoking."

"But on the other hand, when... this strong draught is occasioned by the throat of the Chimney being very near the fire... the draught... may become so strong, as to cause the fuel to be consumed too rapidly. There are likewise several other inconveniences which would attend the placing of the throat of a Chimney very near the burning fuel."

"[T]he height of the throat... will be determined by the height of the mantle. It can hardly be made lower than the mantle; and it ought always to be brought down as nearly upon the level with the bottom of it as possible."

"If the Chimney is apt to smoke, it will sometimes be necessary either to lower the mantle or to diminish the height of the opening of the Fire-place, by throwing over a flat arch, or putting in a straight piece of stone from one side of it to the other, or... building a wall of bricks, supported by a flat bar of iron, immediately under the mantle."

"Nothing is so effectual to prevent Chimnies from smoking as diminishing the opening of the Fire-place in the manner here described, and lowering and diminishing the throat of the Chimnney; and... a perfect cure may be effected by these means alone, even in the most desperate cases."

"[W]hen the construction of the Chimney is very bad... or... very unfavourable to the ascent of the smoke, and especially when both these disadvantages exist... it may... be necessary to diminish the opening of the Fire-place, and particularly to lower It, and also to lower the throat... more than might be wished: but... this can produce no inconveniences to be compared with that greatest of all plagues, a smoking Chimney."

"The position of the throat... being determined, the next points... are its size and form, and the manner in which it ought to be connected with the Fire-place below, and with the open canal of the Chimney above."

"Now the design of a Chimney Fire being... to warm a room... with the smallest expence of fuel... and... that... the air of the room be preserved... pure... fit for respiration, and free from smoke and... disagreeable smells."

"[H]eat which is generated in the combustion of the fuel exists under two... distinct... forms. One... is combined with the smoke, vapour, and heated air which rise from the burning fuel, and goes off with them into the... atmosphere; ...the other part, which appears to be uncombined, or... supposed, combined only with light, is sent off from the fire in rays in all possible directions."

"[I]t is... probable that the combined heat can only be communicated to other bodies by actual contact with the body with which it is combined; and... the rays... communicate or generate heat only when and where they are stopped or absorbed. ...[T]hey seem to bear a great resemblance to the solar rays. ...I must not enter too deeply into... the nature and properties of... radiant heat."

"What proportion does the radiant heat bear to the combined heat? ...[T]he quantity of heat which goes off combined with the smoke, vapour, and heated air is much more considerable, perhaps three or four times greater... And yet, small as the quantity is of... radiant heat, it is the only part... ever employed... in heating a room. The whole of the combined heat escapes by the Chimney, and is totally lost; and... no part of it could ever be brought into a room from an open Fire-place, without bringing along... the smoke..."

"There is, however, one method by which combined heat... may be made to assist in warming a room... by making it pass through something analogous to a German stove, placed in the Chimney above the fire."

"[A]s it is the radiant heat alone which can be employed in heating a room, it becomes an object of much importance to determine how the greatest quantity of it may be generated... and how the greatest proportion possible of that generated may be brought into the room."

"When the fire burns bright, much radiant heat will be sent off from it; but when it is smothered up, very little will be generated... and the combustion being very incomplete, a great part of the inflammable matter of the fuel being merely rarefied and driven up the Chimney without being inflamed, the fuel will be wasted... And hence it appears of how much importance it is, whether.. with a view to economy... cleanliness, comfort, and elegance, to pay due attention to the management of a Chimney Fire."

"Chimnies so often smoke when too large a quantity of fresh coals is put upon the fire. So many coals should never be put on the fire at once as to prevent the free passage of the flame between them. In short, a fire should never be smothered; and when proper attention is paid to the quantity of coals put on, there will be very little use for the poker; and this circumstance will contribute very much to cleanliness, and to the preservation of furniture."

"Now as the rays which are thrown off from burning fuel have this property in common with light, that they generate heat only when and where they are stopped or absorbed, and also in being capable of being reflected without generating heat at the surfaces of various bodies, the knowledge of these properties will enable us to take measures, with the utmost certainty, for producing the effect required... bringing as much radiant heat as possible into the room. This must be done, first, by causing as many as possible of the rays, as they are sent off from the fire in straight lines, to come directly into the room; which can only be effected by bringing the fire as far forward as possible, and leaving the opening of the Fire-place as wide and as high as can be done without inconvenience; and secondly, by making the sides and back of the fire-place of such form, and constructing them of such materials, as to cause the direct rays from the fire, which strike against them, to be sent into the room by reflection in the greatest abundance."

"[T]he best form for the vertical sides of a Fire-place, or the covings... is that of an upright plane, making an angle with the plane of the back of the Fire-place, of about 135 degrees.—According to the present construction of Chimnies this angle is 90 degrees... a right angle; but as... the two sides or covings of the Fire-place are parallel to each other, it is evident that they are very ill contrived for throwing into the room by reflection the rays..."

"As the object... is to bring radiant heat into the room... that material is best for the construction of a Fire-place which reflects the most, or which absorbs the least of it; for that heat which is absorbed cannot be reflected. ...[W]e have only to find out ...what bodies acquire least heat when exposed to the direct rays of a clear fire ...And hence it appears that iron, and ...metals off all kinds, which ...grow very hot when exposed to the rays ...are to be reckoned among the very worst materials ...to employ in the construction of Fire-places."

"The best materials... are fire-stone, and common bricks and mortar. Both... are, fortunately, very cheap..."

"When bricks are used they should be covered with a thin coating of plaster, which, when it is become perfectly dry, should be white-washed. The fire-stone should likewise be white-washed... and every part of the fire-place, which is not exposed to being foiled and made black by the smoke, should be kept as white and clean as possible. As white reflects more heat, as well as more light than any other colour, it ought always to be preferred for the inside of a Chimney Fire-place; and black, which reflects neither light nor heat, should be most avoided."

"[T]he quantity of radiant heat thrown into the room is diminished;—and it is easy to show that almost the whole of that absorbed by the metal is ultimately carried up the Chimney by the air, which, coming into contact with this hot metal, is heated and rarefied by it, and... goes off with the smoke; and as no current of air ever sets from any part of the opening of a Fire-place into the room, it is impossible to conceive how the heat existing in the metal composing any part of the apparatus of the Fire-place, and situated within its cavity, can come, or be brought into the room."

"This difficulty may be in part removed, by supposing... that the heated metal sends off in rays... even when it is not heated red hot; but still, as it never can be admitted that the heat, absorbed by the metal and afterwards thrown off by it in rays, is increased by this operation, nothing can be gained by it; and as much must necessarily be lost... to the air in contact with it, which... always makes its way up the Chimney, and flies off into the atmosphere, the loss of heat attending the use of it is too evident..."

"There is, however, in Chimney Fire-places... one essential part, the grate, which cannot well be made of any thing else but iron..."

"If it should be necessary to diminish the opening of a large Chimney in order to prevent its smoking, it is much more simple, œconomical, and better in all respects, to do this with marble, fire-stone, or even with bricks and mortar, than to make use of iron, which... is the very worst material... for that purpose; and as to registers, they not only are... unnecessary, where the throat of a Chimney is properly constructed, and of proper dimensions, but in that case would do mach harm. If they act It all, it must be by opposing their flat surfaces to the current of rising smoke in a manner which cannot fail to embarrass and impede its motion. But... the passage of the smoke through the throat of a Chimney ought to be facilitated as much as possible in order that it may be enabled to pass by a small aperture."

"Register-stoves have often been found to be of use, but because the great fault of all Fire-places constructed upon the common principles being the enormous dimensions of the throat of the Chimney, this fault has been in some measure corrected by them; but I will venture to affirm, that there never was a Fire-place so corrected that would not have been much more improved, and with infinitely less expence by the alterations here recommended..."

"All Chimney Fire-places, without exception... and even those which do not smoke, as well as those which do, may be greatly improved by making the alterations... here recommended; for it is by no means merely to prevent Chimnies from smoking that these improvements are recommended, but it is also to make them better in all respects... and when the alterations proposed are properly executed, which may very easily be done with the assistance of the following plain and simple directions, the Chimnies will never fail to answer... even beyond expectation. The room will be heated much more equally and more pleasantly with less than half the fuel used before, the fire will be more cheerful and more agreeable; and the general appearance of the Fire-place more neat and elegant, and the Chimney will never smoke."

"I know of no disadvantage... that attends the Fire-places constructed upon the principles here recommended."