in a ship, certain short pieces of rope, which are usually knotted at one or both ends, according to the purpose for which they are designed. They are either used to suspend any heavy body, or to retain a cable, shroud, &c., in a fixed position. Thus, the anchors, when first hoisted up from the ground, are hung to the cat-head by a stopper attached to the latter, which passing through the anchor ring, is afterwards fastened to the timber-head; and the same rope serves to fasten it on the bow at sea; or to suspend it by the ring which is to be sunk from the ship to the bottom. The stoppers of the cable have a large knot and a laniard at one end, and are fastened to a ring-bolt in the deck by the other. They are attached to the cable by the laniard, which is fastened securely round both by several turns passed behind the knot, or about the neck of the stopper; by which means the cable is restrained from running out of the ship when she rides at anchor.

The stoppers of the shroud have a knot and a laniard at each end. They are only used when the shrouds are cut asunder in battle, or disabled by tempestuous weather; at which time they are lashed, in the same manner as those of the cables, to the separated parts of the shroud, which are thereby reunited, so as to be fit for immediate service. This, however, is only a temporary expedient.

**STOPS.** See Punctuation; and Scripture, No. 136.

**STORAX.** See STYRAX, Materia Medica Index.

**STORK.** See ARDEA, Ornithology Index.

**STOVE** for heating apartments, greenhouses, hot-houses, fruit-walls, &c.

When treating of the mechanical properties of air, we explained in sufficient detail the manner in which the expansion produced in a mass of air by heat produces that motion up our chimneys which is called the draught of the chimney; and, in the article SMOKE, we considered the circumstances which tend to check, to promote, or to direct this current, so as to free us from the smoke and vitiated air which necessarily accompanies the consumption of the fuel. In Pneumatics we also attended to the manner in which our fires immediately operate in warming our apartments. At present, when about to describe a method of warming intrinsically different, we must pay some more attention to the distinguishing circumstance. Without pretending to explain the physical connection of heat and light, it may suffice to observe, that heat, as well as light, is communicated to distant bodies in an instant by radiation. A person passing hastily by the door of a glass-house feels the glow of heat in the very moment he sees the dazzling light of the furnace mouth, and it is interrupted by merely screening his face with his hand. In this way is an apartment partly warmed by an open fire; and we avoid the oppressive heat by sitting where the fire is not seen, or by interposing a screen. We are apt to connect this so strongly in the imagination with the light emitted by the fire, that we attribute the heat to the immediate action of the light. But this opinion is shown to be gratuitous by a curious experiment made before the Royal Society by Dr Hooke, and afterwards, with more care and accurate examination, by Mr Scheele. They found, that by bringing a plate of the most transparent glass briskly between the fire and one's face, the heat is immediately intercepted without any sensible diminution of the light. Scheele, by a very pretty investigation, discovered that the glass made the separation, and did it both in refraction and reflection; for he found, that when the light of the same fire was collected into a focus by means of a polished metal concave speculum, a thermometer placed there was instantly affected. But if we employ a glass speculum foiled in the usual manner with quicksilver, of the same diameter and focal distance, and of equally brilliant reflection, there is hardly any sensible heat produced in the focus, and the thermometer must remain there for a very long while before it is sensibly affected. When we repeated this curious experiment, we found, that after the glass has remained a long while in this position, whether transmitting or reflecting the light, it loses in a great measure its power of intercepting the heat. By varying this observation in many of its circumstances, we think ourselves entitled to conclude, that the glass absorbs the heat which it intercepts, and is very quickly heated by the absorption. While it rises in its own temperature, it intercepts the heat powerfully; but when it is, as it were, saturated, attracting no more than what it immediately imparts to the air in corporeal contact with it, the heat passes freely through along with the light. If the glass be held so near the fire that the surrounding air is very much heated, no sensible interruption of heat is perceived after the glass is thus saturated. We found the check more quickly sensible than the thermometer of this instantaneous radiation of the heat which accompanies the light, or is separated from it in this experiment. It is a very instructive experiment in the physiology of heat.

We cannot say how far this radiation of heat may extend, nor whether the accompaniment of light is absolutely necessary. The mathematician proceeds on the supposition that it extends as far as the radiation of light, and that, being also rectilineal, the density of the heat is proportional to that of the light. But these notions are somewhat gratuitous; and there are appearances which render them doubtful. When with a lens of an inch in diameter we form a focus on a piece of black unpolished marble of an inch diameter, the mathematician must allow that no more rays fall on the marble than if the lens were away; therefore the marble should be equally warmed in either case. But it is by no means so, as we have repeatedly found by exposing it during equal times, and then dropping it into water. The water which is heated by the marble on which the focus has been formed will be found to have acquired from it much more heat than from the other. The tops of lofty mountains which are never shaded by clouds, but enjoy perpetual sunshine and serenity, instead of being warmer than the valleys below, are covered with never-melting snow; and we have some grounds to suspect that the genial influence of the sun requires the co-operation of the atmosphere, and to doubt whether there is any warmth at the moon, on which no atmosphere like ours can be observed. Perhaps the heat which cheers us, and fertilizes our earth, is chemically separated from our atmosphere by its elective attraction for the light of the sun. Our successors in the study of meteorology need not fear that the subject of their research will be soon deprived of scientific allurements. We know but little of it after all the progress we have made during this last century, and it still presents an ample field of discussion.

We said that the accompaniment of light is not demonstrably necessary. We are certain that heat may be imparted without any sensible light, in a manner which we can hardly suppose anything but radiation. If a piece of very hot iron be placed a little without the principal focus of a metallic concave speculum, and a very sensible air-thermometer be placed in its conjugate focus, it will instantly show an elevation of temperature, although the iron is quite imperceptible to an eye which has even been a long while in the dark. No such rise of temperature is observed if the thermometer be placed a little to one side of the focus of the speculum; therefore the phenomenon is precisely similar to the radiation of light. We are obliged therefore to acknowledge that the heat is radiated in this experiment in the same way that light is in the common optical experiments.

Although this is the most usual way that we in this country employ fuel for warming our apartments, it is by no means the only way in which the heat diffused from this fuel may be imparted to distant bodies. It is not even the most effectual method; it is diffused also by immediate communication to bodies in contact. The air in immediate contact with the burning fuel is heated and imparts some of its heat to the air lying beyond it, and this is partly shared with the air which is still farther off; and this diffusion, by communication in contact, goes on till the remote air contiguous to the walls, the floor, the ceiling, the furniture, the company, all get a share of it in proportion to their attractions and their capacities. And as the air is thus continually supplied, and continually gives out heat, the walls, &c., become gradually warmer, and the room becomes comfortable and pleasant. But we apprehend that no great proportion of the heat actually acquired by the room is communicated in this way. This diffusion by contact is but slow, especially in air which is very dry; so slow indeed, that the air in the immediate neighbourhood of the fuel is hurried up the chimney before it has time to impart any of the heat received in contact. We know that the time employed in diffusing itself in this way through stagnant air to any moderate distance is very considerable. We imagine therefore that the heat, communicated to our rooms by an open fire is chiefly by radiation, but in a way something different from what we mentioned before. We imagine, that as the piece of glass in Dr Hooke's experiment absorbs the heat, so the whole mass of air which fills the room intercepts the radiated heat in every part of the room where the fire is seen, and is as it were saturated with it throughout, and ready to impart it to every body immersed in it. We cannot otherwise account for the equability of the heat in the different parts of the room. Mere radiation on the solid bodies would warm them in the inverse duplicate ratio of their distances from the fire; and diffusion by contact, if compatible with the rapid current up the chimney, would heat the room still more unequally. Recollect how slowly, and with what rapid diminution of intensity, the colour of blue vitriol is communicated to water even to a very small distance. But because all parts of the air of the room absorb radiated heat, what is saturated at a higher temperature, being nearer to the fire rises to the ceiling, spreads outwards along the ceiling, and has its place supplied by the air, which is thus pushed towards the fire from the places which are not directly illuminated.

Far different is the method of warming the room by a stove. Here the radiation, if any, is very feeble or scanty; and if a passage were allowed up the chimney for the warmed air, it would be quickly carried off. This is well known to the English who reside in the cold climates of St Petersburg, Archangel, &c. They love the exhilarating flotter of an open fire, and often have one in their parlour; but this, so far from warming the room during the extreme cold weather, obliges them to heat their stoves more frequently, and even abstracts the heat from a whole suit of apartments. But all passage this way is shut up when we warm a room by stoves. The air immediately contiguous to the stove is heated by contact, and this heat is gradually, though slowly, diffused through the whole room. The diffusion would however be very slow indeed, were it not for the great expansibility of air by heat. But the air surrounding the stove quickly expands and rises to the ceiling, while the neighbouring air slides in to supply the place, nay is even pushed in by the air which goes outwards aloft. Thus the whole air is soon mixed, and the room acquires almost an equal temperature throughout. The warming by stoves must therefore be managed upon very different principles from those adopted in the employment of open fires. The general principle is, 1st, To employ the fuel in the most effectual manner for heating the external part of the stove, which is immediately efficient in warming the contiguous air; and, 2d, To keep in the room the air already warmed, at least as much as is consistent with wholesomeness and cleanliness.

The first purpose is accomplished by conducting the flue of the furnace round its external parts, or, in short, by making every part of the flue external. Of all forms, that of a long pipe, returned backwards and forwards, up and down (provided only that the place of its last discharge be considerably higher than its entry from the fire-place), would be the most effectual. We have seen a very small stove constructed in this way, the whole being inclosed in a handsome case of polished iron plate, pierced and cut into elegant foliage like the cock of a watch, so that the odd looking pipes were completely concealed. Though only three feet long, one foot thick, and six feet high, it warmed a very lofty room of 24 feet by 18, and consumed less than half the fuel of a stove of the more usual make, which did not so fully warm a smaller chamber.

It would occupy a volume to describe the immense variety of stoves which ingenuity or architectonic taste has constructed. We shall content ourselves with giving a specimen of the two chief classes into which they may be distinguished.

The air of a room may be equally warmed, either by applying it to the surface of a small stove made very hot, or to the surface of a much larger stove more moderately heated. The first kind is chiefly used in Holland, Flanders, and the milder climates of Germany and Poland. The last are universally used in the frozen climates of Russia and Sweden. The first are generally made of cast-iron, and the last of brick-work covered with glazed tiles or stucco.

Fig. 1 represents a small German stove fully sufficient for warming a room of 24 feet by 18. The base is about three feet broad and 14 inches deep, that is, from back to front, and six or seven feet high. The decoration is in the fashion of that country; but the operative structure of it will admit of any style of ornament. A is the fire-place, and the wood or charred coal is laid on the bottom, which has no bars. Bars would admit the air too freely among the fuel, and would both consume it too fast and raise too great a heat. That no heat may be uselessly expended, the sole of the fire-place and the whole bottom of the stove is raised an inch or two above the floor of the room, and the air is therefore warmed by it in succession, and rises upwards. For the same reason the back of the stove is not in contact with the wall of the room, or of the niche in which it is placed. The fire-place is shut up by a door which fits closely to its case, and has a small wicket at the bottom, whose aperture is regulated by a sliding plate, so as to admit no more air than what suffices for slowly consuming the fuel. The flame and heated air rise to the top of the fire-place three or four inches above the arch or mantle-piece, and get out laterally by two narrow passages B, B, immediately below the top-plate of the base. The current bends downward on each side, passes at C, C, under the partition plates which divide the two side chambers, and then rises upwards through the outer division of each, and passes through narrow slits D, D, in the top-plate, and from thence along the two hollow piers E, E. The two lateral currents unite at the top of the arch, and go through the single passage F into the larger hollow behind the escutcheon G. From this place it either goes straight upwards into the vent in the wall by a pipe on the top of the stove, or it goes into the wall behind by a pipe inserted in the back of the stove. The propriety of this construction is very obvious. The current of hot air is applied to exterior parts of the stove everywhere except in the two side chambers of the base, where the partition-plates form one side of the canal. Even this might be avoided by making each of these side-chambers a detached hollow pillar. But this would greatly increase the trouble of construction and joining together, and is by no means necessary. The arch H has a graceful appearance, and affords a very warm situation for anything that requires it, such as a drink in a sick person's bed-chamber, &c. Persons of a certain class use this place for keeping a dish warm; nay, the lower part of the arch is frequently occupied by an inclosed chamber, where the heat rises high enough even for dressing victuals, as will be easily imagined when we reflect that the sole of it is the roof of the fire-place.

The stove now described is supplied with fuel and with air by the front door opening into the room. That there may be room for fuel, this middle part projects a few inches before the two side-chambers. These last, with the whole upper part of the stove, are not more than ten inches deep. The passages, therefore, from the fire-place are towards the back of it; so that if we have a mind to see the fire (which is always cheerful), the door may be thrown open, and there is no danger of the smoke coming out after the current has once warmed the upper part of the stove. When the stove is of such dimensions that the base is about two feet and a half or three feet high, the fire-place may be furnished with a small grate in the British style. If the door is so hung that it can not only be thrown back, but lifted off its hinges, we have a stove grate of the completest kind, fully adequate, in our mild climate, to warm a handsome apartment, even with an open fire; and when we hang on the door, and shut up the fire-place, a stove of the dimensions already given is almost too much for a large drawing-room.

We have frequently remarked, that one side of these stoves grows much warmer than the other, and that it was difficult to prevent or remedy this; and we imagine that this is an unavoidable defect in all stoves with a double flue. It is scarcely possible to make the fire so equable in the fire-place, that one side shall not be a little warmer than the other, and a brisker current will then be produced in it. This must increase the consumption of the fuel on this side, which will increase the current, will heat this side still more, and thus go on continually till the fuel on this side is expended; after which the other side will obtain and increase the superiority. The flue is made double, that the fire-place may occupy the middle of the front; and it will be difficult to gain this point of symmetry with one flue. The inconvenience may, however, be corrected by damping valves placed in some part of the upright funnels E, E. In the colder winters on the continent, it is thought necessary to increase the effect by making the fire-place open to the back of the stove. Its mouth or door communicates with or is joined to an opening of the same dimensions formed in the wall, and the door is on the other side in an antechamber or lobby. In Westphalia, and other places of Germany, the apartments are disposed round a spacious lobby, into which all their fire-places open, and are there supplied with fuel. By this construction it is plain that the air of the room, already warmed by the stove, is not carried off, and the room is more heated. But this method is very unfavourable to cheerfulness and health. The same air, confined, and repeatedly breathed and compounded with all the volatile emanations of the room, quickly loses that refreshing quality that is so desirable, and even so necessary for health. It is never renewed except by very partial admixtures when the room doors are thrown open, and becomes disagreeable to any person coming in from the open air; and in the houses of the less opulent becomes really offensive and nauseous.

Something of this is unavoidable in all rooms heated by stoves. Even in our apartments in this island, persons of delicate nerves are hurt by what they call the close air of a room; and it is long before the smell of dinner is quite removed from a dining-room, notwithstanding the copious current up the chimney. This must be incomparably more sensible in a room heated by a stove; and this inconvenience is peculiarly sensible with respect to the stove which we are considering at present, where we employ a small surface heated to a great degree.

Such stoves are seldom made of anything else than cast-iron. This (in those parts at least which are in immediate contact with the fuel) is in a state of continual calcination, and even throwing off scales. This indeed is not seen, because it is the bottom or sole of the fireplace which is so heated; but the effect on the air of the room is the same. The calcination of the iron is occasioned by the combination of pure vital air with the iron. This is abstracted from the general mass of atmospheric air in the room, of which it usually constitutes about two-fifths. By this abstraction the remainder becomes less fit for supporting animal life or flame, and may even become highly deleterious. In every degree the remainder becomes less refreshing, and grows dull and oppressive. This is always accompanied by a peculiar smell, which, though not disgusting, is unpleasant. It resembles the smell of burnt feathers, or more exactly the smell we feel if we rub violently for some time the palms of our hands together when perfectly dry.

For similar reasons these iron stoves occasion a sickly smell, by burning every particle of dust which falls on the hot parts; and if they be wiped with a woollen cloth, or any cloth not perfectly free from every kind of greasy or oily matter, a smell is produced for a day or days afterwards; so that without the most scrupulous attention we suffer by our very cleanliness.

For such reasons we think that the stoves of brick-work covered with stucco or with glazed tiles are vastly preferable. These are much used in the gentry's houses in Flanders and Holland, where they are made in the most elegant forms, and decorated with beautiful sculpture or enamel; but it is plain that they cannot be so effectual, nor equally warm a room with the same expense of fuel. Earthen ware, especially when covered with porous stucco, is far inferior to metal in its power of conducting heat. If built of bricks, they must be vastly more bulky when the fire-place and flues are of the same dimensions. The most perfect way of constructing them would certainly be to make them of pottery, in parts exactly fitted to each other, and joined by a proper cement. This mode of constructing would admit of every elegance of form or richness of ornament, and would not be so bulky as those which are built of bricks. The great difficulty is to prevent their cracking by the heat. Different parts of the stove being of very different heats, they expand unequally, and there is no cement which can withstand this, especially when we recollect that the same heat which expands the baked earth causes the clay or cement, with which the parts of the stove are put together or covered, to contract. Accordingly those earthen ware stoves seldom stand a winter or two without cracking in some place or other, even when strengthened by iron hoops and cramps judiciously disposed within them. Even hooping them externally, which would be very unsightly, will not prevent this; for nothing can resist the expansion and contraction by heat and cold. When a crack happens in a stove, it is not only unsightly, but highly dangerous; because it may be so situated, that it will discharge into the room the air vitiated by the fire.

For these and other reasons, we can scarcely hope to make stoves of brick work or pottery which shall bear the necessary heat without cracking; and their use must therefore be confined to cases where very moderate heat is sufficient. We need not describe their construction. It is evident that it should be more simple than that of iron stoves; and we imagine that in the very few cases in which they are likely to be employed in this country, a single fire-place, and an arch over it, divided, if we please, by a partition or two of thin tile to lengthen the floor, will be quite enough. If the stove is made in whole or in part of potters ware, a base for the fireplace, with an urn, column, obelisk, or pyramid above it, for increasing the surface, will also be sufficient. The failure commonly happens at the joinings, where the different pieces of a different heat, and perhaps of a different baking, are apt to expand unequally, and by working on each other one of them must give way. Therefore, instead of making the joints close and using any cement, the upper piece should stand in a groove formed in the undermost, having a little powdered chalk or clay sprinkled over it, which will effectually prevent the passage of any air; and room being thus given for the unequal expansion, the joint remains entire. This may be considered as a general direction for all furnace work, where it is in vain to attempt to hinder the mutual working of the parts.

We have seen stoves in small apartments at St Petersburg, which were made internally of potters ware, in a great variety of forms, and then covered with a thick coat of stucco, finished externally with the utmost elegance of ornament, and we were informed that they were very rarely subject to crack. They did not give much heat, on account of the very low conducting power of the porous stucco; but we imagine that they would be abundantly warm for a moderate room in this country. When fitted up in these situations, and with these precautions, the brick or pottery stoves are incomparably more sweet and pleasant than the iron ones.

But in the intense colds of Russia and Sweden, or even for very large rooms in this kingdom, stoves of these small dimensions are not sufficiently powerful, and we must follow the practice of those countries where they are made of great size, and very moderately heated. It is needless to describe their external form, which may be varied at pleasure. Their internal structure is the same in all, and is distinctly described in Pneumatics, No. 364. We shall only enlarge a little on the peculiarities connected with the general principle of their construction.

The stove is intended as a sort of magazine, in which a great quantity of heat may be quickly accumulated, to be afterwards slowly communicated to the air of the room. The stove is therefore built extremely massive; and it is found that they are more powerful when coated with clay as wet as can be made to hang together. We imagine the reason of this to be, that very wet clay, and more particularly stucco, must be exceedingly porous when dry, and therefore a very slow conductor of heat. Instead of sticking on the glazed tiles with no more clay or stucco than is sufficient to attach them, each tile has at its back a sort of box baked in one piece about two or three inches deep. It is represented in fig. 2. This is filled with mortar, and then stuck on the brick-work of the stove, which has a great number of iron pins or hooks driven into the joints, which may sink into this clay and keep it firmly attached when dry. This coating, with the massive brick-work, forms a great mass of matter to be heated by the fuel. The lowest chamber, which is the fire-place, is somewhat wider, and considerably thicker than the stories above, which are merely flues. When the fire-place is finished and about to be arched over, a flat iron bar of small thickness is laid along the top of the side-wall on both sides, a set of finishing bricks being moulded on purpose with a notch to receive the iron bar. Cross bars are laid over these, one at each end and one or two between, having a bit turned down at the ends, which takes hold of the longitudinal bars, and keeps them from being thrust outwards either by the pressure of the arch or by the swelling in consequence of the heat. In fig. 3. A is the cross section of one of the long bars, and BC is part of one of the cross bars, and CD is the clench which confines the bar A. This precaution is chiefly necessary, because the contraction of the stove upwards obliges the walls of the other stories to bear a little on the arch of the fire-place. The building above is kept together in like manner by other courses of iron bars at every second return of the flue. The top of the stove is finished by a pretty thick covering of brick-work. The last passage for the air at H (see Pneumatics, fig. 62.) has a ring lining its upper extremity, and projecting an inch or two above it. The flat round it is covered with sand. When we would stop this passage, a covered shape like a bason or cover for dishes at table is wheeled over it. The rim of this, resting on the sand, effectually prevents all air from coming through and getting up the vent. Access is had to this damper by a door which can be shut tight enough to prevent the heated air of the room from wasting itself up the vent. When the room is too warm, it may be very rapidly cooled by opening this door. The warm air rushes up with great rapidity, and is replaced by cool air from without.

The management of the stove is as follows. About eight o'clock in the morning the pietchnick, or servant who has the charge of the stoves, takes off the cover, shuts the damper-door, and opens the fire-place door. He then puts in a handful of wood shavings or straw, and kindles it. This warms the stove and vent, and begins a current of air through it. He then lays a few chips on the sole of the fire-place, immediately within the door; and behind this he arranges the billets of birchwood with their ends inwards. Then he lays on more wood in the front, till he thinks there is enough. He sets fire to the chips, shuts the door and opens the small wicket at its bottom. The air blows the flame of the chips upon the billets behind them, and thus kindles them. They consume slowly, while the billets in front remain untouched by the fire. The servant, having made his first round of the rooms, returns to this stove, and opens the door above to admit air into the vent. This is to supply its draught, and thus to check the draught in the body of the stove, which is generally too strong at this time, and would consume the fuel too fast. By this time the billets in the front are burning, first at the bottom, and the rest in succession as they sink down on the embers and come opposite to the wicket. The room does not yet feel any effect from the fire, the heat of which has not yet reached its external surface; but in about half an hour this grows warm. The upper door is shut again, that no heat may now be wasted. The pietchnick by and by spreads the embers and ashes over the whole bottom of the fire-place with a rake, by which the bottom is greatly heated, and heats the air contiguous to it externally (for it stands on little pillars) very powerfully. He takes care to bring up to the top of the ashes every bit of wood or coal that is not yet consumed, that all may be completely expended. He does this as briskly as possible, that the room may not lose much warmed air by keeping open the fire-place door. At his last visit, when he observes no more glowing embers, he shuts the fire-place door and wicket, and puts the damper on the passage above, and shuts its door.—All this is over in about an hour and a half after kindling the fire. All current of air is now at an end within the stove, and it is now a great mass of brick-work, heated to a great degree within, but only about blood-warm externally. The heat gradually spreads outwards, and the external surface of the stove acquires its greatest heat about three o'clock in the afternoon; after which it gradually cools till next morning.

This heat seldom is so great that one cannot bear to touch the stove with his cheek, and to keep it there. In consequence of this it can burn none of the dust which unavoidably falls on the stove, and we are never troubled with the sickening smells that are unavoidable when we employ the small cast-iron stoves much heated. The great expense of heat in a room arises from the glass windows. The pane is so thin that the external air keeps it continually cold, and thus the windows are continually robbing the air of the room of its heat. This expense of heat is reduced to less than one-third by double casements. The inner casement is about as much colder than the room as the outer casement is warmer. warmer than the air of the fields; and we have the singular advantage of having no ice formed on the glasses. But to ensure this last advantage, the seams of the inner casement must be pasted with paper, and those of the outer casement must be left unpasted. If we do the contrary, we shall certainly have ice on the outer casement; the reason of which is easily seen.

We have been thus particular in our description of the management, because the reasons of some particulars are not very obvious, and the practice would not readily occur to us in this country; so that a person who, on the faith of our recommendation, should prefer one of these stoves to the German stove, whose management is simple and obvious, might be greatly disappointed. But by following this method, we are confident that the Russian stove will be found much superior both in warmth and agreeable air. The spreading out of the embers, and waiting till all is reduced to ashes before the doors are shut, is also absolutely necessary, and a neglect of it would expose us to eminent danger of suffocation by fixed air; and this is the only inconvenience of the Russian stove, from which the other stove is free. The fixed air has no smell; and the first indication of its presence is a slight giddiness and lassitude, which disposes us to sit down and to sleep. This would be fatal; and we must immediately open the upper passage and the fireplace door, so as to produce a strong current to carry the vitiated air of the room up the chimney. Throwing up the sashes, or at least opening all the doors, is proper on such an occasion.

If we burn pit-coal, either raw or charred, this precaution is still more necessary; because the cinder is not so easily or so soon completely consumed. This fuel will require a little difference in the management from wood fuel, but which is easily seen by any person of reflection. The safe way would be to rake out all half-burnt coal before shutting up the doors.

If we use raw pit-coal, great care is necessary to prevent the accumulation of soot in the upper part of the stove. It is an inaccessible place for the chimney-sweep; and if we attempt to burn it out, we run a great risk of splitting that part of the stove which is the most slightly constructed. It is advisable therefore to burn it away every day, by giving a brisk draught with an open door for five minutes. With wood or coak there is no danger.

It will not be improper in this place to give some instructions for the construction of stoves for warming several floors in a great manufactory, such as a cotton-mill, or a public library or museum.

In such situations we think cleanliness, wholesomeness, and sweetness of air, no less necessary than in the drawing-room of a man of opulence. We therefore recommend the brick-stove in preference to the iron one; and though it would not be the best or most economical practice to heat it but once a-day, and we should rather prefer the German practice of constant feeding, we still think it highly proper to limit the heat to a very moderate degree, and employ a large surface.

If the disposition of the rooms allows us the convenience of a thick party-wall, we would place the stove in the middle of this wall, in an arch which pierces through the wall. Immediately above this arch we would carry up a very wide chimney through the whole height. This chimney must have a passage opening into each floor on both sides, which may be very accurately shut up by a door. The stove being set up under the arch, it must have a pipe communicating with its flue, and rising up through this chimney. Could an earthen pipe be properly supported, and secured from splitting by hoops, we should prefer it for the reasons already given. But as this is perhaps expecting too much, we must admit the use of a cast iron pipe. This is the real chimney or flue of the stove, and must be of as great diameter as possible, that it may act, by an extensive surface, all the way up.

The stove stands under the arch in the wall; but the air that is warmed by its surface would escape on both sides, and would be expended in that single floor. To prevent this, the stove must be inclosed in a case: this may be of brick-work, at the distance of two or three inches from the stove all round. It must be well shut in above, and at the foundation must have a row of small holes to admit the air all around it. This air will then be warmed over the whole space between the stove and the case, pass up the chimney, and there receive additional heat from the flue-pipe which is in the middle. Great care must be taken that the fire-place door have no communication with the space between the stove and its case, but be inclosed in a mouth-piece which comes through the case, and opens into the feeding-room. Thus all the air which goes up to the rooms will be pure and wholesome, provided we take care that everything be kept clean and sweet about the air-holes below. Observe that those air-holes which are near the furnace door must be inclosed in a wooden trunk which takes in its air at some distance from this door; for since the current between the stove and case may be almost as great as the current within the stove (nay, when a puff of wind beats down the chimney, it may even exceed it), there is a risk of some vitiated air and smoke being drawn into the case.

If the stove cannot be placed in the arch of a party-wall, it may be set adjoining to a side or outer wall, and furnished with a case, a large chimney, and a flue-pipe, in the same manner. But in this case a great deal of heat is wasted on this outer wall, and carried off by the external air. In this situation we would recommend to line that part of the wall which is behind the stove (at two or three inches distance), and the whole of the chimney, with plaster or laths. These should be nailed on battens properly fastened on the wall, leaving a space of an inch between the laths and the wall. The plaster should be of the most spongy kind, having in it a quantity of clay in powder instead of the full proportion of sand. Horse-dung, washed with water and strained through coarse flannel, leaves a great portion of unassimilated vegetable fibre, which will mix very intimately in the plaster, and make it a substance very unfit for conducting heat. There is no danger of catching fire by this lining. We have seen a most tremendous fire rage for three-hours, in contact with a partition of lath and plaster (on the plaster-side however), without discouraging the thin laths on the other side. We once saw a cottage chimney on fire, and burn till the soot was consumed. This chimney was nothing but a pipe of a foot wide, made of laths, and plastered on the inside and outside; and it passed through a thatched roof. We therefore recommend this in place of the brick-case for inclosing the stove. It would save heat; and as it might he made in pieces on detached frames, which could be joined by iron straps and hinges, any part of the stove could be laid open for repairs at pleasure.

We have no hesitation in saying that a stove constructed in this manner would be greatly superior in power to any we have seen, and would be free from many of their disgusting defects. We beg leave therefore to introduce here the description of one which was to have been erected in one of the churches of the city of Edinburgh.

Fig. 4. is a sketch of the plan of the church contained in the parallelogram AFED. P marks the place of the pulpit, and LMNO the front of the galleries. These are carried back to the side walls AB and DC. But at the end opposite to the pulpit they do not reach so far, but leave a space BFFC about 12 feet wide. Below the back of the galleries, on each side, there is a passage ABGH, KICD, separated from the seated part of the church by partitions which reach from the floor to the galleries, so that the space HGIK is completely shut in. The church is an ancient Gothic building, of a light and airy structure, having two rows of large windows above the arcades, and a spacious window in the east end above the pulpit. The congregation complain of a cold air, which they feel pouring down upon their heads. This is more particularly felt by those sitting in the fronts of the galleries. We imagine that this arises chiefly from the extensive surface of the upper row of windows, and of the cold stone-walls above, which robs the air of its heat as it glides up along the sides of the church. It becomes heavier by collapsing, and in this state descends in the middle of the church.

The stove S is placed against the middle of the west wall at the distance of a few inches, and is completely inclosed in a case of lath and plaster. The vent, which is to carry off the smoke and burnt air, is conveyed up or along the wall, and through the roof or side-wall, but without any communication with the case. In like manner the fire-place door is open to the passage, without communicating with the case; and care is taken that the holes which admit the air into the case are so disposed that they shall run no risk of drawing in any air from the fire-place door.

From the top of this case proceed two trunks Q, R, each of which is two feet broad and six inches deep, coated within and without with the most spongy plaster that can be composed. For this purpose we should recommend a composition of powdered charcoal and as much clay and quicklime as will give it a very slight cohesion. We know that a piece of this may be held in the hand, without inconvenience, within an inch of where it is of a glowing red heat.—These trunks open into another trunk XVTZ, which ranges along the partition immediately under the galleries, and may be formed externally into a cornice, a little massive indeed, but not unsightly in a building of this style. This trunk is coated in the same manner. It has several openings a, a, &c., which have sliders that can be drawn aside by means of handles accessible from the outer passage.—At the extremities X and Z of this trunk are two perpendicular trunks which come up through the galleries, and are continued to a considerable height. At their junction with the horizontal trunk are two doors large enough to admit a lamp. Each perpendicular trunk has also a valve by which it can be completely stopped.

The stove is managed as follows: Early in the morning the superintendent shuts all the sliders, and sets a lamp (burning) in each of the trunks X and Z, and shuts the doors. He then puts on and kindles the fire in the stove, and manages it either in the Russian or German method. Perhaps the latter is preferable, as being liable to fewer accidents from mistake or neglect.

The lamps set in the lower ends of the upright trunks presently warm them, and produce a current of air upwards. This must be supplied by the horizontal trunk, which must take it from the case round the stove. Thus a current is begun in the direction we wish. By and by the air in the case acquires heat from the stove, and the current becomes extremely brisk. When the manager perceives this, he removes the lamps, shuts the valves, and opens the holes a, a, &c., beginning with the most remote, and proceeding slowly towards the stove from each extremity of the horizontal branches. The heated air now issues by these holes, glides along the ceiling below the galleries, and escapes, by rising up along the fronts of the galleries, and will be sensibly felt by those sitting there, coming on their faces with a gentle warmth. It will then rise (in great part) straight up, while some of it will glide backwards, to the comfort of those who sit behind.

The propriety of shutting the valves of the upright trunks is evident. If they were left open, no air would come out by the holes a, a, &c.; but, on the contrary, the air would go in at these holes to supply the current, and the stove be rendered useless. The air delivered by these holes will keep close to the ceiling, and will not, as we imagine, inconvenience those who sit below the galleries. But if it should be found to render these parts too warm, holes may be pierced through the ceiling, by which it will rise among the people above, and must be very comfortable. It will require the careful attention of some intelligent person to bring all this into a proper train at first, by finding the proper apertures of the different holes, so as to render the heat equable through the whole space. But this being once ascertained the difficulty is over.

The air trunks must be very capacious, but may be contracted towards the extremities as their lateral discharges diminish; and the row of holes which admit the air to the case round the stove must be fully able to supply them.

It must be observed, that in this construction the ascensional force is but small. It is only the height of a short column of warm air from the ground to the galleries. At first indeed it is great, having the unlimited height of the perpendicular trunks at X and Z; but during the use of the stove it is reduced to nine or ten feet. It is necessary, therefore, that the stove be highly heated, perhaps considerably beyond the Russian practice, but yet inferior to the heat of the German iron stoves. But still we strongly recommend the brick or pottery stoves, on account of the wholesome sweetness of the air which they furnish: and we are certain that a stove of moderate dimensions, eight feet long, for instance, by eight feet high, will be sufficient for warming a church holding 1200 or 1500 people. If the stove could be placed lower, which in many situations is very practicable, its effect would be proportionally greater, because all depends on the rapidity of the current. When we are limited in height, we must extend the store stove so much the more in length, and make the air trunks more capacious. These and many other circumstances of local modification must be attended to by the erecter of the stove; and without the judicious attention of an intelligent artist, we may expect nothing but disappointment. It is hardly possible to give instructions suited to every situation; but a careful attention to the general principle which determines the ascensional force will free the artist from any great risk of failure.

We may say the same thing of stoves for conservatories, hot-houses, hot-walls, &c., and can hardly add anything of consequence to what we have already said on these heads in the article Pneumatics.

We must not, however, dismiss the subject without taking notice of the very splendid projects which have been frequently offered for drying malt by stoves. Many of these are to be seen in the publications of the Academies of Stockholm, Upsal, Copenhagen; and some have been erected in this kingdom, but they have not been found to answer.

We apprehend that they cannot answer. To dry malt, and make it fit for the ales and beers for which this island is so famous, it is by no means enough that we give it a proper and an equable supply of heat.—This alone would bake it and make it flinty, causing the moisture to penetrate the mealy particles of the grain; and, by completely dissolving the soluble parts, would render each kernel an uniform mass, which would dry into a flinty grain, breaking like a piece of glass.—A grain of malt is not an inert pulp. It is a seed, in an active state, growing, and of an organized structure. We wish to stop it in this state, and kill it, not by heating it, but by abstracting its moisture. We thus leave it in its granulated or organized form, spongy, and fit for imbibing water in the mash tub, without running into a paste.

To accomplish these purposes, the construction of our malt kilns seems very well adapted. The kiln is the only flue of the furnace, and a copious current of air is formed through among the grains, carrying off with it the water which is evaporating by the heat. But this evaporation, being chiefly in consequence of the vapour being immediately dissolved by the passing air, will stop as soon as the current of air stops. This current has to make its way through moist grain, laid in a pretty thick bed, and matted together. Some force, therefore, is necessary to drive it through. This is furnished by the draught of the kiln. Substituting a stove, immediately applied to the malt, will not have this effect. The only way in which we think this can be done different from the present, is to have a horizontal flue, as has been proposed in these projects, spread out at a small distance below the grate on which the malt is laid, and to cover the whole with a high dome, like a glass-house dome. This being filled with a tall column of hot air, and having no passage into it but through the malt, would produce the current which we want. We are convinced that this will make much less fuel serve; but we are by no means certain that the sulphureous and carbonic acid which accompanies the air in our common kiln is not a necessary or a useful ingredient in the process. It is well known that different coaks, cinders, or charcoals, impart different qualities to the malts, and are preferred each for its own purpose.

A patent stove constructed on similar principles, but composed of very different materials, has been lately erected in several of the churches in Edinburgh. This stove, which is formed entirely of cast iron, may be considered as a double stove, an outer case, and a furnace or inner stove. The fuel is burnt in the inner stove; and the smoke produced during the process of combustion, is carried off by a chimney, which passes through the top of the outer stove, and is conveyed to the outside of the building. The outer case includes not only the furnace or inner stove, but also a considerable space, occupied by the air of the atmosphere, which is freely admitted through a number of openings placed around it; and when any current of air is produced, it passes off from the space between the outer case and inner stove, and is conveyed by tubes through the body of the apartment. But we shall first describe the different parts of which the stove is composed, after which we shall be better able to understand its mode of operation.

Fig. 5. exhibits a perspective view of this stove. AB is the body, which is about three feet high, and of a circular form. BC is a square pedestal on which the stove is placed, and which contains the ash pit DD. The height of the pedestal is about a foot, and it is nearly insulated by resting on the spherical supports aa, also of cast iron. EEE are openings in front of the ash pit through which the air enters to support the combustion. These openings can be enlarged or diminished, or opened and shut at pleasure. FF is the door of the furnace through which the fuel is introduced. This door is attached to the inner furnace, and is double. It is one foot broad, and 11 inches high. GG is the chimney, which passes from the furnace within, through the outer case, and conveys the smoke out of the building. HH are openings in the outer case, and are eight in number, through which the air enters, and being heated, is greatly rarified, and passes off through the funnel or pipe IIII. This pipe communicates only with the outer stove, and being shut at the end K, the air rushes out from the small tubes LL, inserted into the side of the pipe IIII, and thus mixes with the cold air of the church. The diameter of the outer case at the bottom is about two feet, and the diameter of the furnace within is about 16 inches.

Fig. 6. is a section of the stove. AB is the outer case, from which passes off the pipe or funnel CCC, by which the heated air is conveyed through the church. DD is the furnace in the inside, in which the fuel is burnt, and EEE is the chimney or funnel which conveys the smoke from the inner furnace out of the building. It passes through the outer stove AB at F.

Fig. 7. is a plan of this stove. AB is the pedestal on which it rests, and which contains the ash pit. CC is the outer case, and DD is the furnace within, in which are seen the transverse bars which support the fuel.

The length of the body of the church, in which two stoves of the form and dimensions now described are erected, is about 60 feet, and the breadth is about 45 feet. The tubes IIII are conveyed along the lower edge of the gallery, about half the length of the church. The fires are lighted up about four or five o'clock on the Sunday morning, during the earlier part of the cold season; but as the season advances, it is usual to light them up the night before. From this time till the congregation assemble for the afternoon service, the furnaces are are kept constantly supplied with fuel. By this management the air in the church is kept comfortably warm during the coldest season of the year.

These stoves, it appears to us, are susceptible of some improvement, both in their construction and in the places in which they are erected. With regard to the first circumstance, an external coating of plaster work, or of the same kind of materials as are used for coating the inside of chemical furnaces, would be of some use in preventing an unnecessary waste of heat, as well as the disagreeable smell which is sometimes complained of, and which is supposed to arise from the combustion of light bodies floating in the air and drawn by the current to the heated metal; and with regard to the last, viz., the places in which they are erected, it is perfectly obvious that they ought to be as completely insulated as possible, and particularly ought not to communicate with good conductors of heat. Some of the stoves erected in the churches of Edinburgh are faulty in this respect. But to the use of this stove there is a stronger objection. The air that is heated has circulated through the apartment, and has been respired and consequently vitiated. Hence some unpleasant effects have arisen from its use.

A stove erected by Mr A. Kilpatrick, tinsmith in Edinburgh, is free from this serious objection. In his stoves the whole of the air heated is conveyed from the outside of the building. Stoves of this description answer well for heating large halls, staircases, and churches.

The following is the description of an improved stove by Mr Field of Newman Street London, in which, it is stated by the author, the various advantages of heating, boiling, steaming, evaporating, drying, ventilating, &c., are united; some of which we shall detail in his own words.

"Fig. 8. represents a longitudinal section of the stove, showing the course of the air from its entrance into the flues of the stove at A, to its entrance into the upper chamber of the stove at B; and also the course of the smoke from the fire-place at C, till it escapes from the stove at D. E, E, are the doors or openings of the fireplace and ash-hole.

"Fig. 9. is a similar section at right angles with the above, exhibiting the course of the air through the chambers of the stove, from its entrance into the chamber No. 1, at B to its entrance beneath the fire-place at F. This figure also shows sections of the flues, with the divisions through which the air and smoke pass separately, the smoke-flue in the centre, and the air-flues, on each side, G, G, are doors and openings through which the articles to be dried are introduced into the chambers.

"When the fire is lighted, and the doors of the chambers, ash-hole, and fire-place, closed, the air by which the fire is supplied enters at A, fig. 8, passes through the air-flues a, a, a, enters the upper chamber at B, traverses and descends through the chambers No. 1, 2, 3, and arrives beneath the fire at F, fig. 9. Having supplied the fire with oxygen, it passes through the flue with the smoke, and escapes at D, heating in its protracted course the chambers and air-flues.

"As the cold air enters the stove at A, immediately above a plate forming the top of the fire-place, and pursues a similar route with the fire-flue, it enters the chambers very much heated and rarefied. Hence any moist substance placed in the chambers evaporates in consequence, not only of the heated flues circulating round them, but of a stream of warm rarefied air, which, while it continually raises evaporation, as continually bears away the exhaled moisture in its passage to the fire, thus imitating the gradual and efficacious plan of nature in drying by the sun and air. While these effects are taking place within the stove, part of the air which enters at A, fig. 8, and g, passes through air-flues on the other side of the fire-flue, pursues a parallel course with the first, and gives out a current of warm air to the room at an aperture H. This effect may be obtained in a much higher degree, if the doors of the chambers and ash-hole are opened; should the hand or face be then brought near, they would be fanned with a stream of warm air, especially from the upper chamber.

"By means of this stove I have evaporated milk to dryness, without burning or discolouring it; and have dried cherries, plums, and other fruits, so as to imitate those which are received from abroad. I have repeatedly dried colours and the most delicate substances without the slightest injury, even though the operation proceeded quickly.

"The height of the stove is about five feet and a half; its diameter two feet and a half; and that of the flues four inches. The external part is constructed of brick, and the internal parts of thin Rye gate or fire-stone, except the top of the fire-place, which is a plate of cast iron. Were it to be wholly formed of iron, its effects would necessarily be more powerful.

"Fig. 10. represents an extension of the plan, in which stoves of this kind may be advantageously connected with one or more furnaces for chemical or other uses. The fire-place, brought out, either in front or on one side, by the present positions of its crown I, forms a reverberatory furnace, or will make a sand-bath by reversing it.

"The space occupied by the fire-place in fig. 8, may in this be converted into apartments for evaporating substances, or occasionally for cooling them by an opening at K to admit cold air, while the warm air of the stove is excluded by a register or door. The dotted lines show the manner in which a second furnace may be connected by an opening into the flue at L.

"In addition to the uses already pointed out, this stove would probably be found extremely serviceable in drying jammers goods, and consuming the noxious fumes and gas which arise from the oil and varnish used in this business.

"Since the stove is not limited to any certain dimensions, it might be adapted to the drying of malt and hops, perhaps of herbs, corn, and seeds generally. It might also be accommodated to the purpose of the sugar-bakers, connected with the great fires they employ for their boilers. It has been shown to be useful in the confectioners art, and probably it may be equally so in baking biscuits for the navy; nor less so in drying linen for the laundress, dyer, calico-printer, and bleacher. I have myself found it well accommodated for a chemical laboratory."