a particular part of a house well known, which Professor Beckmann has, in our opinion, proved to be an invention comparatively modern. It would be very unfair dealing in us to give even a large abstract of one of the most curious dissertations of a curious book, which has been but lately published, and thereby injure the interest of him to whom the native of Britain is indebted for the pleasure of perusing it in his own tongue. No man, however, can blame us for here flinging, in support of our own opinion, the professor's answer to the passage of Ferrari, which we have quoted under the word Chimney in the Encyclopaedia.

"When the triumvirate, says Appian," caused those who had been profligated by them to be sought for by the military, some of them, to avoid the bloody hands of their persecutors, hid themselves in wells, and others, as Ferrarius translates the words, in fumaris fide tellis, qua sollicitus fumus a tellis evoluitur (A). The true translation, however, (says Mr Beckmann) is fumum excrecens. The principal persons of Rome endeavoured to conceal themselves in the smoky apartments of the upper story under the roof, which, in general, were inhabited only by poor people; and this seems to be confirmed by what Juvenal expressly says, Rarum venit in conacula sed miles.

"Those passages of the ancients which speak of smoke rising up from houses, have with equal improbity been supposed to allude to chimneys, as if the smoke could not make its way through doors and windows. Seneca writes, 'Last evening I had some friends with me, and on that account a stronger smoke was raised; not such a smoke, however, as bursts forth from the kitchens of the great, and which alarms the watchmen, but such a one as signifies that guests are arrived.' Those whose judgments are not already warped by prejudice, will undoubtedly find the true sense of these words to be, that the smoke forced its way through the kitchen windows. Had the houses been built with chimney-funnels, one cannot conceive why the watchmen should have been alarmed when they observed a stronger smoke than usual arising from them; but as the kitchens had no conveniences of that nature, an apprehension of fire, when extraordinary entertainments were to be provided in the houses of the rich for large companies, seems to have been well founded; and on such occasions people appointed for that purpose were stationed flationed in the neighbourhood to be constantly on the watch, and to be ready to extinguish the flames in case a fire should happen. There are many other passages to be found in Roman authors of the like kind, which it is hardly necessary to mention; such as that of Virgil:

'Et jam summa procul villarum culmina fumant.'

and the following words of Plautus, descriptive of a miser:

'Quin divum atque hominum clamat continuo fidem, Sumam rem perifile, seque eradicariet, De tuo tigillo fumus si qua exit foras.'

In the Vespas of Aristophanes, referred to in the Encyclopaedia, old Philocleon wishes to escape through the kitchen. Some one asks, "What is that which makes a noise in the chimney?" "I am the smoke (replies the old man), and am endeavouring to get out at the chimney." This passage, however (says the professor) which, according to the usual translation, seems to allude to a common chimney, can, in my opinion, especially when we consider the illustration of the scholiasts, be explained also by a simple hole in the roof, as Reiske has determined; and indeed this appears to be more probable, as we find mention made of a top or covering, with which the hole was closed.

In the Encyclopaedia we have said, that the instances of chimneys remaining among the ruins of ancient buildings are few, and that the rules given by Vitruvius for building them are obscure; but we are now satisfied that there are no remains of ancient chimneys, and that Vitruvius gives no rules, either obscure or peripatetic, for building what, in the modern acceptation of the word, deserves the name of a chimney.

The ancient mason-work still to be found in Italy does not determine the question. Of the walls of towns, temples, amphitheatres, baths, aqueducts, and bridges, there are some though very imperfect remains, in which chimneys cannot be expected; but of common dwelling houses none are to be seen, except at Herculaneum, and there no traces of chimneys have been discovered. The paintings and pieces of sculpture which are preserved, afford us as little information; for nothing can be perceived in them that bears the smallest resemblance to a modern chimney.

"If there were no funnels in the houses of the ancients to carry off the smoke, the directions given by Columella, to make kitchens so high that the roof should not catch fire, was of the utmost importance. An accident of the kind, which that author seems to have apprehended, had almost happened at Beneventum, when the landlord who entertained Mecenas and his company was making a strong fire in order to get some birds sooner roasted.

ubi fedulas hoppes

Pene arift, macros dum turlos verfat in igne; Nam vaga per veterem dilapfo flamma culniam Vulcano fummum properabat lambere tectum."

Had there been chimneys in the Roman houses, Vitruvius certainly would not have failed to describe their construction, which is sometimes attended with considerable difficulties, and which is intimately connected with the regulation of the plan of the whole edifice. He does not, however, say a word on this subject; neither does Julius Pollux, who has collected with great care the Greek names of every part of a dwelling-house; and Grapaldus, who in later times made a collection of the Latin terms, has not given a Latin word expressive of a modern chimney."

Our author admits the derivation of the word chimney to be as we have given it in the Encyclopaedia; but (says he) "Cumimae lignitum, as far as I have been able to learn, first a chemical or metallurgic furnace, in which a crucible was placed for melting and refining metals; secondly, a smith's forge; and, thirdly, a hearth on which portable fires or fire-panes were placed for warming the apartment. In all these, however, there appears no trace of a chimney." Herodotus relates (lib. viii. c. 137.), that a king of Libya, when one of his servants asked for his wages, offered him in jest the sun, which at that time shone into the house through an opening in the roof, under which the fire was perhaps made in the middle of the edifice. If such a hole must be called a chimney, our author admits that chimneys were in use among the ancients, especially in their kitchens; but it is obvious that such chimneys bore no resemblance to ours, through which the sun could not dart his rays upon the floor of any apartment.

However imperfect may be the information which can be collected from the Greek and Roman authors respecting the manner in which the ancients warmed their apartments, it nevertheless shows that they commonly used for that purpose a large fire-pot or portable stove, in which they kindled wood; and, when the wood was well lighted, carried it into the room, or which they filled with burning coals. When Alexander the Great was entertained by a friend in winter, as the weather was cold and raw, a small fire-basin was brought into the apartment to warm it. The prince, observing the size of the vessel, and that it contained only a few coals, desired his host, in a jeering manner, to bring more wood or frankincense; giving him thus to understand that the fire was fitter for burning perfumes than to produce heat. Anacharsis, the Scythian philosopher, though displeased with many of the Grecian customs, praised the Greeks, however, because they shut out the smoke and brought only fire into their houses. We are informed by Lampridius, that the extravagant Ite liogabulus caused to be burned in these stoves, instead of wood, Indian spices and costly perfumes. It is also worthy of notice, that coals were found in some of the apartments of Herculaneum, as we are told by Winklemann, but neither stoves nor chimneys."

It is well known to every scholar, that the useful arts of life were invented in the east, and that the customs, manners, and furniture of eastern nations, have remained from time immemorial almost unchanged. In Persia, which the late Sir William Jones seems to have considered as the original country of mankind, the methods employed by the inhabitants for warming themselves have a great resemblance to those employed by the ancient Greeks and Romans for the same purpose. According to De la Valle, the Persians make fires in their apartments, not in chimneys as we do, but in stoves in the earth, which they call tenor. These stoves consist of a square or round hole, two spans or a little more in depth, and in shape not unlike an Italian cist. That this hole may throw out heat former, and with more strength, there is placed in it an iron vessel of the same size, which is either filled with burning coals, or a fire of wood and other inflammable substances is made in it. When this is done, they place over the hole or stove a wooden top, like a small low table, and spread above it a large coverlet quilted with cotton, which hangs down on all sides to the floor. This covering condenses the heat, and causes it to warm the whole apartment. The people who eat or converse there, and some who sleep in it, lie down on the floor above the carpet, and lean, with their shoulders against the wall, on square cushions, upon which they sometimes also sit; for the tenor is constructed in a place equally distant from the walls on both sides. Those who are not very cold only put their feet under the table or covering; but those who require more heat can put their hands under it, or creep under it altogether. By these means the stove diffuses over the whole body, without causing uneasiness to the head, so penetrating and agreeable a warmth, that I never in winter experienced anything more pleasant. Those, however, who require less heat let the coverlet hang down on their side to the floor, and enjoy without any inconvenience from the stove the moderately heated air of the apartment.

They have a method also of stirring up or blowing the fire when necessary, by means of a small pipe united with the tenor or stove under the earth, and made to project above the floor as high as one chooses; so that the wind, when a person blows into it, because it has no other vent, acts immediately upon the fire like a pair of bellows. When there is no longer occasion to use this stove, both holes are closed up, that is to say, the mouth of the stove and that of the pipe which conveys the air to it, by a flat stone made for that purpose. Scarcely any appearance of them is then to be perceived, nor do they occasion inconvenience, especially in a country where it is always customary to cover the floor with a carpet, and where the walls are plastered. In many parts, these ovens are used to cook viands, by placing kettles over them. They are employed also to bake bread; and for this purpose they are covered with a large broad metal plate, on which the cake is laid; but if the bread is thick and requires more heat, it is put into the stove itself."

Our learned author having proved, to our entire satisfaction, that chimneys, such as we have now in every comfortable room, were unknown to the most polished nations of antiquity, sets himself to inquire into the era of their invention; and the oldest account of them which he finds is an inscription at Venice, which relates, that in the year 1347 a great many chimneys were thrown down by an earthquake. It would appear, however, that in some places they had been in use for a considerable time before that period; for De Gaturis, in his history of Padua, relates, that Francesco de Carrao, lord of Padua, came to Rome in 1368, and finding no chimneys in the inn where he lodged, because at that time fire was kindled in a hall in the middle of the floor, he caused two chimneys like those which had long been used at Padua to be constructed by masons and carpenters, whom he had brought along with him. Over these chimneys, the first ever seen at Rome, he affixed his arms, which were still remaining in the time of De Gaturis, who died of the plague in 1425.

Though chimneys have been thus long in use, they are yet far enough from being brought to perfection. There is hardly a modern house, especially if highly finished, in which there is not one room at least liable to be filled with smoke when it is attempted to be heated by an open fire; and there are many houses so infested with this plague, as to be almost uninhabitable during the winter months; not to mention other great defects in common chimneys, which not being so obvious have attracted less attention. Many ingenious methods have been proposed to cure smoky chimneys in every situation (see Smoke, Encycl.); but Count Rumford's Essay on this subject contains the most valuable directions that we have seen, not only for removing the inconvenience of smoke, but likewise for increasing the heat of the room by a diminished consumption of fuel.

To those who are at all acquainted with the nature and properties of elastic fluids, it must be obvious, that the whole mystery of smoking chimney consists in finding out and removing the accidental causes which prevent the heated smoke from being forced up the chimney by the pressure of the cool and therefore heavier air of the room. Though these causes are various, yet says our author, that which will most commonly be found to operate, is the bad construction of the chimney in the neighbourhood of the fire-place. "The great fault of all the open fire-places or chimneys for burning wood or coals in 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."

To this fault, therefore, the attention should be first turned in every attempt which is made to improve the construction of chimneys; for however perfect a fireplace may be in other respects, 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, draughts of cold air cannot fail to be produced in the room, to the great annoyance of those who inhabit it. But although both these evils may be effectually remedied by reducing the throat of the chimney to a proper size, yet in doing this several precautions will be necessary. And first of all, the throat of the chimney should be in its proper place; that is to say, in that place in which it ought to be, in order that the ascent of the smoke may be most facilitated; now as the smoke and hot vapour which rise from a fire naturally tend upward, the proper place for the throat of the chimney is evidently perpendicularly over the fire.

But there is another circumstance to be attended to in determining the proper place for the throat of a chimney, and that is, to ascertain its distance from the fire, or how far above the burning fuel it ought to be placed. In determining this point there are many things to be considered, and several advantages and disadvantages to be weighed and balanced.

As the smoke and vapour which ascend from burning fuel rise in consequence of their being rarefied 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 further, as they are hotter Now the quantity of radiant heat generated in the combustion of a given quantity of any kind of fuel depends very much upon the management of the fire, or upon the manner in which the fuel is consumed. 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 indeed very little combined heat that can be employed to any useful purpose: most of the heat produced will be immediately expended in giving elasticity to a thick dense vapour or smoke, which will be seen rising from the fire; 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 to little purpose. And hence it appears of how much importance it is, whether it be considered with a view to economy, or to cleanliness, comfort, and elegance, to pay due attention to the management of a chimney fire.

Nothing can be more perfectly void of common sense, and wasteful and slovenly at the same time, than the manner in which chimney fires, and particularly where coals are burned, are commonly managed by servants. They throw on a load of coals at once, through which the flame is hours in making its way; and frequently it is not without much trouble that the fire is prevented from going quite out. During this time no heat is communicated to the room; and what is still worse, the throat of the chimney being occupied merely by a heavy dense vapour, not polished of any considerable degree of heat, and consequently not having much elasticity, the warm air of the room finds less difficulty in forcing its way up the chimney and escaping than when the fire burns bright. And it happens not unfrequently, especially in chimneys and fire places ill-constructed, that this current of warm air from the room which presses into the chimney, crowding upon the current of heavy smoke which rises slowly from the fire, obstructs it in its ascent, and beats it back into the room; hence it is that chimneys 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.

As we have seen what is necessary to the generation of the greatest quantity of radiant heat, it remains to be determined how the greatest proportion of that which is generated and sent off from the fire in all directions may be made to enter the room, and afford in warming it.

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 a 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.

Now it will be found upon examination, that the best form for the vertical sides of a fire-place, or the covings (as they are called), is that of an upright plane, making an angle with the plane of the back of the fireplace of about 135 degrees. According to the present construction of chimneys, this angle is sometimes only 90°, and very seldom above 100 or 110 degrees; but it is obvious, that in all these cases the two sides or covings of the fire place are very ill-contrived for throwing into the room by reflection the rays from the fire which fall upon them.

With regard to the materials which should be employed in the construction of fire-places, particularly the backs and covings, it is obvious that those are to be preferred which absorb the least, and of course reflect the greatest quantity of radiant heat. Iron, therefore, and, in general, metals of all kinds, are the very worst materials which can possibly be employed for the backs and covings of chimneys; whilst fire stone white-washed, or common bricks and mortar, covered with a thin coating of plaster, and white-washed, answer the purpose extremely well. A white colour should, indeed, be always given to the inside of a chimney of whatever materials it be constructed; and black, which is at present so common, should be carefully avoided, because white reflects the most, and black the least, radiant heat. The grate, however, cannot well be made of anything else than iron; but there is no necessity whatever for that immense quantity of iron which surrounds grates as they are commonly fitted up, and which not only renders them very expensive, but essentially injures the fire-place.

To have only pointed out the faults of the chimneys in use, without shewing how these faults may be corrected, would have been a work of very little value; but the Count's Treatise is complete, and contains the plainest directions for the construction of fire-places. These directions are introduced by an explanation of some technical words and expressions. Thus, by the throat of a chimney, already mentioned, he means 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.

Fig. 1. shews the section of a chimney on the common construction, in which d e is the throat.

Fig. 2. shews the section of the same chimney altered and improved, in which d i is the reduced throat.

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.—In the figures 1. and 2. it is marked by the letter d. The width of the throat of the chimney (d e fig. 1. and d i fig. 2.) 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 (a fig. 1. and 2.).

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 in fire-places proposed by the Count, it is evident that both these may be attained merely by bringing forward the back of the chimney. The only question therefore is, How far it should be brought forward? The answer is short, and easy to be understood: 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 he calls the throat of the chimney, ought, for reasons which have been already explained, 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 than to ascertain how wide the throat of the chimney ought to be left, or what space 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.

Numerous experiments have convinced the Count, that, all circumstances being well considered; and the advantages and disadvantages compared and balanced, four inches is the best width that can be given to the throat of a chimney, whether the fire place be destined to burn wood, coals, turf, or any other fuel. In very large halls where great fires are kept up, it may sometimes, though very rarely, be proper to increase this width to four inches and a half, or even to five inches.

The next thing to be considered is the width which it will be proper to give to the back of the chimney; and, in most cases, this should be one-third of the width of the opening of the fire-place in front. It is not indeed absolutely necessary to conform with rigour to this decision, nor is it always possible; but it should invariably be conformed to as far as circumstances will permit. Where a chimney, says the Count, 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 fire-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 39 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. This position, indeed, it may sometimes be impossible to attain in altering chimneys already built; but a deviation from it of two or three degrees will be of no great consequence; for the points of by much 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 the proper width.

Provision, however, must be made for the passage of the chimney-tweezer up the chimney; and this may easily be done in the following manner: In building up the new back of the fire-place; when this wall (which need never be more than the width of a single brick brick in thickness) is brought up so high that there remains no more than about ten or eleven inches between what is then the top of it and the inside of the mantle, or lower extremity of the breast of the chimney; an opening or door-way, eleven or twelve inches wide, must be begun in the middle of the back, and continued quite to the top of it, which, according to the height to which it will commonly be necessary to carry up the back, will make the opening abundantly sufficient to let the chimney-sweeper pass. When the fire-place is finished, this door-way is to be closed by a tile or flat piece of stone placed in it without mortar, and by means of a rabbit made in the brick-work, confined in its place in such a manner as that it may be easily removed when the chimney is to be swept, and restored to its place when that work is over. Of this contrivance the reader will be able to form a clear conception from fig. 2: which represents the section of a chimney after it has been properly altered from what is exhibited in fig. 1. In this improved chimney K is the new back of the fire-place; L is the tile or stone which closes the door-way for the chimney-sweeper; M is the throat of the chimney narrowed to four inches; N is the mantle, and O is the stone placed under the mantle, supposed to have been too high, in order to diminish the height of the opening of the fire-place in front.

It has been observed above, that the new back, which it will always be found necessary to build in order to bring the fire sufficiently forward, in altering a chimney constructed on the common principles, need never be thicker than the width of a common brick. The same may be said of the thickness necessary to be given to the new flues or covings of the chimney; or if the new back and covings are constructed of stone, one inch and three quarters, or two inches in thickness, will be sufficient. Care should be taken in building up these new walls to unite the back to the covings in a solid manner.

Whether the new back and covings are constructed of stone or built of bricks, the space between them and the old back and covings of the chimney ought to be filled up, to give greater solidity to the structure. This may be done with loose rubble, 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, that is to say, 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. This course of bricks will be upon a level with the top of the door-way left for the chimney-sweeper; and the void behind the door-way must be covered with a horizontal stone or tile, to be removed at the same time the door is removed, and for the same purpose.

From these descriptions it is clear, that where the throat of the chimney has an end, that is to say, 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. It is of much importance that they 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 shift the wind, 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 of the chimney.

As the two walls which form the new covings of the chimney are not parallel to each other, 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, it is evident that 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 twirls, bends, prominences, excavations, and other irregularities of form in the covings of a chimney, 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 it appears, that the covings of chimneys should never be made circular, or in the form of any other curve, but always quite flat.

For the same reason, that is to say, to prevent eddies, the breast of the chimney, which forms that side of the throat that is in front or nearest to the room, should be neatly cleaned off, and its surface made quite regular and smooth. This may be easily done by covering it with a coat of plaster, 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.

With regard to the form of the breast of a chimney, this is a matter of very great importance, and which ought always to be particularly attended to. The worst form it can have is that of a vertical plane or upright flat; and next to this the worst form is an inclined plane. Both these forms cause the current of warm air from the room, which will, in spite of every precaution, 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 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 of course ought always to be done.

Having thus ascertained the form and position of the new covings, the ingenious author next turns his attention to the height to which they should be carried. This will depend not only on the height of the mantle, but 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 for instance, higher than this part, otherwise the throat of the chimney will not be properly formed; but no advantage would be gained by carrying them higher.

One important circumstance respecting chimney fireplaces still remains to be considered; and that is the grate. In placing the grate, the thing principally to be attended to is, to make the back of it coincide with the back of the fire-place. But as many of the grates now in common use will be found to be too large, when the fire-places are altered and improved, it will be necessary to diminish their capacities by filling them up at the back and sides with pieces of fire-stone. When this is done, it is the front of the flat piece of fire-stone which is made to form a new back to the grate, which must be made to coincide with, and make part of the back of the fire-place.—But in diminishing the capacities of grates with pieces of fire-stone, care must be taken not to make them too narrow.

The proper width for grates destined for rooms of a middling size will be from six to eight inches, and their length may be diminished more or less according as the room is heated with more or less difficulty, or as the weather is more or less severe.—But where the width of a grate is not more than five inches it will be very difficult to prevent the fire from going out.

It frequently happens that the iron backs of grates are not vertical, or upright, but inclined backwards.—When these grates are too much too wide as to render it necessary to fill them up behind with fire stone, the inclination of the back will be of little consequence; for by making the piece of stone with which the width of the grate is to be diminished in the form of a wedge, or thicker above than below, the front of this stone, which in effect will become the back of the grate, may be made perfectly vertical; and the iron back of the grate being hid in the solid work of the back of the fire-place, will produce no effect whatever; but if the grate be already too narrow as not to admit of any diminution of its width, in that case it will be best to take away the iron back of the grate entirely, and fixing the grate firmly in the brick-work, cause the back of the fire-place to serve as a back to the grate.

Where grates, which are designed for rooms of a middling size, are longer than 14 or 15 inches, it will always be best, not merely to diminish their lengths, by filling them up at their two ends with fire-stone, but, forming the back of the chimney of a proper width, without paying any regard to the length of the grate, to carry the covings through the two ends of the grate in such a manner as to conceal them, or at least to conceal the back corners of them in the walls of the covings.

Had these directions been duly attended to by the masters who in Scotland pretend to alter chimneys on the principles of Count Rumford, we should not have observed so many of the grates placed by them jutting out beyond the mantle of the chimney; nor of course heard so many complaints of rooms being rendered more smoky and the consumption of fuel increased by these pretended improvements. But when the grate is not set in its proper place, when its sloping iron back is retained, when no pains have been taken to make its ends coincide with the covings of the fire place, when the mantle, instead of having its back rounded off, is a vertical plane of iron cutting the column of smoke which rises beneath it, and, above all, when the throat of the chimney, instead of four, is made, as we often see, fourteen inches wide; let it be remembered, that not one of Count Rumford's directions has been followed, and that his principles have as little to do with the construction of such a chimney as with the building of the wall of China or the pyramids of Egypt.

To contribute our aid to prevent these blunders for the future, we shall here subjoin the Count's directions for laying out the work; not to instruct masons and bricklayers, to whom we earnestly recommend the study of the essay itself (a), which contains much valuable information that we have omitted; but merely to give the country gentleman an opportunity of discovering whether the workmen whom he employs deviates far and needlessly from the principles which he pretends to follow.

When a chimney is to be altered, after taking away the grate and removing the rubbish, first draw a straight line with chalk, or with a lead pencil, upon the hearth, from one jamb to the other,—even with the front of the jambs. The dotted line A B, fig. 3., may represent this line.

From the middle c of this line, (A B) another line c d, is to be drawn perpendicular to it, across the hearth, to the middle d, of the back o: the chimney.

A person must now stand upright in the chimney, with his back to the back of the chimney, and hold a plumb-line to the middle of the upper part of the breast of the chimney (d, fig. 1.), or where the canal of the chimney begins to rise perpendicularly;—taking care to place the line above in such a manner that the plumb may fall on the line c d (fig. 3.), drawn on the hearth from the middle of the opening of the chimney in front to the middle of the back, and an assistant must mark the precise place e, on that line where the plumb falls.

This being done, and the person in the chimney having quitted his station, four inches are to be set off on the line c d, from c, towards d; and the point f, where these four inches end, (which must be marked with chalk, or with a pencil,) will show how far the new back is to be brought forward.

Through f, draw the line g b parallel to the line A B, and this line g b will show the direction of the new back, or the ground line upon which it is to be built. The line c f will show the depth of the new fire place; and if it should happen that c f is equal to about one-third of the line A B, and if the grate can be accommodated to the fire-place instead of its being necessary to accommodate the fire-place to the grate; in that case, half the length of the line c f is to be set off from f on the line g b, on one side to k, and on the other to i, and the line i k will show the ground line of the fore part of the back of the chimney.

In all cases where the width of the opening of the fire-place in front (A B) happens to be not greater, or not

(a) It costs but two shillings; and he must be a poor bricklayer indeed who cannot afford to pay that sum for instruction in the most important, as well as most difficult, part of his business. not more than two or three inches greater than three times the width of the new back of the chimney (i k), this opening may be left; and lines drawn from i to A, and from k to B, will show the width and position of the front of the new covings—but when the opening of the fire-place in front is still wider, it must be reduced; which is to be done in the following manner:

From c, the middle of the line A B, c a and c b must be set off equal to the width of the back (i k), added to half its width (f i); and lines drawn from i to a, and from k to b, will show the ground plan of the fronts of the new covings.

When this is done, nothing more will be necessary than to build up the back and covings; and if the fire-place is designed for burning coals, to fix the grate in its proper place, according to the directions already given.—When the width of the fire place is reduced, the edges of the covings a A and b B are to make a finish with the front of the jambs.—And in general it will be best, not only for the sake of the appearance of the chimney, but for other reasons also, to lower the height of the opening of the fire place whenever its width in front is diminished.

A front view of the chimney, after it has been thus altered, is exhibited in fig. 4, where the under part of the door-way is represented, as clothed by the white dotted lines.

When the wall of the chimney in front, measured from the upper part of the breast of the chimney to the front of the mantle, is very thin, it may happen, and especially in chimneys designed for burning wood upon the hearth, or upon dogs, that the depth of the chimney, determining according to the directions here given, may be too small.

Thus, for example, supposing the wall of the chimney in front, from the upper part of the breast of the chimney to the front of the mantle, to be only four inches, (which is sometimes the case, particularly in rooms situated near the top of a house), in this case, if we take four inches for the width of the throat, this will give eight inches only for the depth of the fire-place, which would be too little, even were coals to be burnt instead of wood.—In this case (says the Count) I should increase the depth of the fire-place at the hearth to 12 or 13 inches, and should build the back perpendicular to the height of the top of the burning fuel (whether it be wood burnt upon the hearth or coals in a grate); and then, sloping the back by a gentle inclination forward, bring it to its proper place, that is to say, perpendicularly under the back part of the throat of the chimney. This slope, (which will bring the back forward four or five inches, or just as much as the depth of the fire-place is increased), though it ought not to be too abrupt, yet it ought to be quite finished at the height of eight or ten inches above the fire, otherwise it may perhaps cause the chimney to smoke; but when it is very near the fire, the heat of the fire will enable the current of rising smoke to overcome the obstacle which this slope will oppose to its ascent, which it could not do so easily were the slope situated at a greater distance from the burning fuel.

Fig. 5, 6, and 7, show a plan, elevation, and section of a fire-place constructed or altered upon this principle.—The wall of the chimney in front at a, fig. 7, being only four inches thick, four inches more added to it for Chimney, the width of the throat would have left the depth of the fire-place measured upon the hearth b c only eight inches, which would have been too little;—a niche c and e was therefore made in the new back of the fire-place for receiving the grate, which niche was six inches deep in the centre of it, below 13 inches wide, (or equal in width to the grate,) and 23 inches high; finishing above with a semicircular arch, which, in its highest part, rose seven inches above the upper part of the grate.—The door-way for the chimney-sweeper, which begins just above the top of the niche, may be seen distinctly in both the figures 6 and 7.—The space marked g, fig. 7, behind this door-way, may either be filled with loose bricks, or may be left void.—The manner in which the piece of stone f, fig. 7, which is put under the mantle of the chimney to reduce the height of the opening of the fire place, is rounded off on the inside in order to give a fair run to the column of smoke in its ascent through the throat of the chimney, is clearly expressed in this figure. The plan fig. 5, and elevation fig. 6, show how much the width of the opening of the fire-place in front is diminished, and how the covings in the new fire-place are formed.

A perfect idea of the form and dimension of the fireplace in its original state, as also after its alteration, may be had by a careful inspection of these figures.

In chimneys, like that represented in figure 8, where the jambs A and B project far into the room, and where the front edge of the marble slab o, which forms the coving, does not come so far forward as the front of the jambs, the workmen in constructing the new covings are very apt to place them,—not in the line c A, which they ought to do,—but in the line c o, which is a great fault.—The covings of a chimney should never range behind the front of the jambs, however those jambs may project into the room;—but it is not absolutely necessary that the covings should make a finish with the internal front corners of the jambs, or that they should be continued from the back e, quite to the front of the jambs at A.—They may finish in front at a and b; and small corners A, o, a, may be left for placing the shovels, tongs, &c.

Were the new coving to range with the front edge of the old coving s, the obliquity of the new coving would commonly be too great;—or the angle d c o would exceed 135 degrees, which it never should do,—or at least never by more than a very few degrees. No inconvenience of any importance will arise from making the obliquity of the covings less than what is here recommended; but many cannot fail to be produced by making it much greater.

These extracts, which we have made so liberally from Count Rumford's essay on chimney fire-places, will be sufficient, we hope, to bring fully within the comprehension of those who are acquainted with pneumatics, and pneumatic chemistry the principles on which chimneys and fire-places should be constructed; but such as are in a great measure strangers to these sciences will do well to consult the essay itself. With a benevolence which does him honour, the ingenious author has expressed a wish that his doctrines on this important subject may be widely propagated; and to encourage artists to study them, he has declared to the public in general, that "as he does not intend to take out himself, Chimney-Sweepers are a class of men who earn their subsistence by clearing chimneys of soot, which occasions them to smoke. While chimneys continued to be built in so simple a manner, and of such a width as they are still observed to be in old houses, they were so easily cleaned that this service could be performed by a servant with a wisp of straw, or a little brushwood fastened to a rope; but after the fires, in order to save room, were made narrower, or when several flues were united together, the cleaning of them became so difficult, that they required boys, or people of small size, accustomed to that employment. The first chimney-sweepers in Germany came from Savoy, Piedmont, and the neighbouring territories. There for a long time were the only countries where the cleaning of chimneys was followed as a trade; and hence Professor Beckmann concludes with great probability, that chimneys were invented in Italy. The Lotharingians, however, undertook the business of chimney-sweeping also; on which account the duke of Lotharingia was styled the imperial fire-smoker. The first Germans who condescended to clean chimneys were miners; and the chimney-sweepers in that empire still procure their boys from the forest of Harz, where the greatest mines are wrought. Very lately, and perhaps at present, the greater part of the chimney sweepers in Paris were Savoyards, many of them not above eight years of age, who, for the paltry sum of five sous, which they were obliged to share with their avuncular master, would scramble, at the hazard of their lives, through a narrow funnel fifty feet in length, and with their bellows clean it from foot and dirt. At what precise period chimney-sweeping became a trade in England and Scotland, we have not been able to learn; but among us, as well as elsewhere, young boys are employed in this business, who are said to be very harshly treated by fellows who stole them from the doors of cottages in the country. That children have been sometimes kidnapped by chimney-sweepers, we can have no doubt; but that the practice is frequent, we do not believe. We think however that the business might be wholly abolished; for a narrow funnel might certainly, if not very crooked, be swept by a bundle of straw or brushwood fastened to a rope, as well as one that is wider; and the bricks which separate the contiguous flues we know to be less injured by this method of sweeping, when cautiously gone about, than by sending boys up the chimneys.

On the 4th of July 1796, letters patent were granted to Daniel Davis, of the parish of St Giles Middlesex, for his invention of a machine, by which he proposes to sweep and cleanse chimneys, and extinguish chimneys on fire, without any person going up the same, as is now the practice. The machine consists of an apparatus of rack-work, of various lengths, which, by means of a hand-turn, is made to ascend the chimney. The lengths of the rack-work are joined together by means of mortices and tenons, with a spring which holds them fast. In each length is a joint, by which the rack-work will accommodate itself to angles or turns in the flues. To the first or uppermost length is affixed a brush of hair, or wire, or sponge, or other elastic substance, as the occasion may require.

This invention is doubtless well calculated to answer the purpose intended, and may perhaps be the means of diminishing the number of those objects of misery, the unfortunate chimney-sweepers.