Warming

27. Hardingâ€™s Ventilator.

Hardingâ€™s ventilators are better known in the north of England than the south. They are recommended by Pridgin Teale, surgeon to the General Infirmary at Leeds, as a means of securing freshness of atmosphere without draught, and free from all mixture of dust, soot, or fog. The outside air is conducted through a grate and aperture in the wall about 7 ft. 6 in. above the floor level, where it is made to pass through a series of small tubes fixed at an angle of about 30Â° with the wall. The currents of air are said to be compressed while passing through the tubes, but to expand and diffuse in all directions as soon as they are liberated into the apartment. In all filtering arrangements it must be remembered that if air is to pass through a screen or filter without retarding the current entering the room through a tube, the area of the screen must be greater than the area of section of the tube. This can be effected by placing the screen diagonally within the tube which admits the air. In some buildings the filter is dispensed with, and the apparatus is used simply to diffuse the air as it enters the room. An outlet for the vitiated air is provided by the chimney flue, either through the fireplace or by a mica valve placed in the flue near the ceiling. In rooms whereflues do not exist an air extractor is provided, consisting of two perforated cones and a central tube. The external air impinging upon the perforated cones is deflected, creating an induced current up the vertical tube, drawing the foul air from the interior of the room, and expelling it through the perforations. In fixing the extractor, a wooden base or frame is placed on the ridge and covered with lead to make it watertight; the extractor is then placed over this and fixed in the ordinary manner. A small inner cone is provided simply to prevent rain from getting into the tube. Hardingâ€™s extractors are so designed that they may be easily fixed inside an ornamental turret without in any way affecting their action. They can be obtained in London from Strode & Co., at prices varying from 15s.to 6l.and upwards. Their action is illustrated in Fig. 27:a, wall;b, grating outside;c, filter.

Another system for admitting fresh air into a room, free from fog and other impurities, is that recommended by the Sanitary Engineering and Ventilating Co., 115, Victoria Street, Westminster. They provide for the introduction of fresh air in vertical currents by means of a suitable number and disposition of vertical tubes, varying in size, section, and weight according to each special case. The current can be regulated in amount by throttle valves, and the heated or vitiated air is removed by means of exhaust ventilators, placed directly over the roof or in connection with air flues and shafts. The exhaust ventilator is thus described by the makers: There are no working parts to get out of order, and no attention is required to ensure its constant action. In this respect, a great improvement is claimed over the numerous forms of revolving cowls, which require occasional lubrication, otherwise the working parts become corroded and the cowl ceases to act. They are made of circular or rectangular section, or other shapes to suit special circumstances. One great merit of the system is the element of length which is introduced by means of the tube arrangement, and thus a current is continually passing which diffuses itself over the room. The system admits of a patent air-cleansing box being built into the wall at the foot of the tube, fitted with special deflector plates and a tray to hold water or, when necessary, disinfectants. When the arrangements of furniture or fittings in a room preclude the use of vertical tubes fixed near the ground, they recommend the substitution of a ventilating bracket fixed at 6-7 ft. above the floor. This bracket may contain an air purifying or cleansing box; if required, a valve is provided for regulating the admission of fresh air, and a 9 in. by 6 in. hinged air grating to cover the opening outside. The air-cleansing box is illustrated in Fig. 28:a, inside of room;b, floor;c, trough or tray for holding water or disinfectant fluid;d, tube.

28. Sanitary Ventilating Companyâ€™s Ventilator.

Boyleâ€™s patent self-acting air-pump ventilators are well known, and are found to answer well in their continuous action under all varieties of wind pressure; they are often adopted without any inquiry being made as to the scientific principles on which they are constructed. They consist of 4 sections, each acting independently of the other. The exterior curve baffle-plate prevents the wind blowing through the slits formed in the immediate interior plates, and tends to concentrate the current. These interior plates are curved outwards, so as to take the pressure off the vertical slits,which form a communication with the internal chambers, through which the air impinges on inner deflecting plates, and is further directed by the radial plates. The external air impinging on the radial plates is deflected on to the side plates, and creates an induced current. In its passage it draws the air from the central vertical chambers, expelling it at the opposite opening. The vitiated air immediately rushes up the shaft connecting the ventilator with the apartment to be ventilated, extracting the air and producing a continuous upward current without the possibility of down draught. The partitions separating the chambers prevent the external air being drawn through the slits upon which the wind is not directly acting. The whole arrangement being a fixture, with no mechanical movement, it is never liable to get out of order, and the apparatus can be easily fixed over a wood base or frame covered with zinc or lead to secure a good water-tight connection. Where Boyleâ€™s ventilators are used the air is renewed imperceptibly, the vitiated air being extracted as rapidly as it is generated.

A somewhat similar arrangement to Boyleâ€™s ventilator is patented by Arnold W. Kershaw, of Lancaster, and consists of 3 rims of deflectors or plates with openings in each, so arranged that the openings in one rim are opposite the deflectors in the next inner or outer rim, the effect being that whatever the direction of the wind, it passes through the ventilator without being able to enter the central shaft, and in passing creates a partial vacuum, which induces an upward current in the upcast shaft without the possibility of down draughts. Both Boyleâ€™s and Kershawâ€™s roof ventilators are suitable for fixing in ventilating towers or turrets. While Kershawâ€™s is somewhat simpler in construction, Boyleâ€™s is said to possess the additional advantage of preventing the entrance of snow by the curve in which the inner plates are fixed. In the case of chimney flues where there is any obstruction that breaks the wind and produces a swirl, such as would be caused by close proximity to higher buildings or raised gables, a down draught may be prevented by the use of a properly-constructed chimney cowl. Kershawâ€™s chimney cowl is a modification of his pneumatic ventilator, and consists of deflecting plates so arranged that there is no possibility of a down draught. Boyleâ€™s chimney cowl is better known than Kershawâ€™s, and is very effective. It consists of deflecting plates so fixed that if a body of air is forced in at the false top, instead of passing down the vent, it is split up by an inner diaphragm, deflected over the real top, and passed over at the side openings, thus checking the blow down and assisting the up draught. Kershawâ€™s patent inlet and air diffuser consists of a tube connection between the outside and inside of an apartment rising vertically on the inside, the upper extremity having radiating plates, which diffuse the incoming current. Generally speaking, a sufficient amount of fresh air enters under the door to a room or between the window sashes or frames; but in apartments where doors and windows fit tightly, some arrangement for the admission of fresh air becomes indispensable. In this climate, during 7 months of the year, the external air is usually too cold to be admitted directly into the room.

The plan of admitting fresh air to a space behind the grates, leading up the air through channels on each side of the fireplace, and ultimately passing it through perforated gratings within the wall or through perforations in the skirting board on each side of the fireplace cannot be commended, as the passages are apt to get choked up with dust, and the temperature of the air cannot be well regulated in its passage into the room. The true object of a fire and chimney flue should not be to supply fresh air, but to extract it after it has done its work.

29. Boyleâ€™s Air-cooler.

Fig. 29 illustrates Boyleâ€™s arrangement for cooling the air entering a room in hot weather. It consists of an air-inlet tube of bracket form, made of iron. The partwhich penetrates the hole in the wall has an outer casing, so that a space of about Â½ in. is left between, which is packed with a non-conducting substance, for the purpose of preventing the heat from the wall penetrating into the interior of the opening and acting upon the blocks of ice, which are placed in a movable drawer, and kept in position by means of open galvanised iron or copper-wire netting. The front of the drawer is also double, and packed same as casing. The outer air entering through the grating is deflected by a metal shield on to the suspended blocks of ice, and from thence on to the ice at the bottom of the drawer, and thence up the tube into the room. The air is not only cooled, but purified thoroughly from dust. See also p.991.

Warming.â€”In connection with warming an apartment, it is obviously a necessary condition that the warmth shall be conserved as much as possible. Hence there is an evil in having too much glass, as it cools the room too fast in the winter season: 1 sq. ft. of window glass will cool 1Â½ cub. ft. of warm air in the room to the external temperature per second; that is, if the room be warmed to 60Â° F., and the thermometer stands at 30Â° F. outside, there will be a loss of 90 cub. ft. of warm air at 60Â° per second from a window containing a surface of glass of 60 sq. ft. In colder climates than that of England, this subject is of much greater importance. In America, for instance, during the cold weather, there will always be found, no matter how tightly or closely the sashes are fitted and protected with weather-strips, a draught of cold air falling downward. This arises from the contact of the heated air with the cold glass, which renders the air cooler and heavier, and causes it to fall. The air, at the same time, parts with a considerable proportion of its moisture by condensation upon the glass. The cold air thus formed falls to the floor, forming a layer of cold air, which surrounds the feet and legs, while the upper part of the body is enveloped in overheated air. The layers of cold and warm air in an apartment will not mix. The warm air will not descend, and the cold air cannot go upward, except the one is deprived of its heat by radiation, and the other receives its heat by actual contact with a heated surface. This radical difference in the upper and lower strata of atmosphere of the rooms, in which people live during the cold season, is the prolific cause of most of the throat and lung diseases with which they are afflicted. Double windows to the houses, therefore, would not only be a great economy as to fuel, but highly conductive to human longevity.

There are only two ways in which dwelling-houses can be heated, namely, by radiant heat and by hot air. The former is produced by the open fire, and by it alone. The latter is obtained in various ways. The question whether we shall use hot air or radiant heat in our rooms is by no means one to be lightly passed over. Instinct tells us to select radiant heat, and instinct is quite right; it is so because radiant heat operates in a very peculiar way. It is known that as a matter of health it is best to breathe air considerably below the natural temperature of the bodyâ€”98Â° F.; in air heated to this temperature most persons would in a short time feel stifled. But it is also known that the body likes, as far as sensation is concerned, to be kept at a temperature as near 98Â° F. as may be, and that very much higher temperatures can be enjoyed; as, for example, when we sit before a fire, or bask in the sun. Now radiant heat will not warm air as it passes through it, and so, at one and the same time, we can enjoy the warmth of a fire and breathe that cool air which is best suited to the wants of our system. Herein lies the secret of the popularity of the open fireplace. But in order that the open fireplace may succeed, it must be worked within the proper limits of temperature. If air falls much below 40Â° F. it becomes unpleasant to breathe; and it is also very difficult to keep the body warm enough when at rest by any quantity of clothes. In Russia and Canada the temperature of the air outside the houses often falls far below zero, and in the houses it cannot be much above the freezing-point. Here the open fire fails; it can only warm air by first heating the walls, furniture, and other materials in a room, and these, in turn, heat the air with which they come in contact. But this will not do for North American winters; and accordingly in Canadaand the United States the stove or some other expedient for warming air by direct contact with heated metal or earthenware is imperatively required. But this is the misfortune of those who live in cold climates, and when they ask us to follow their example and take to close stoves and steam-pipes, and such like, they strongly remind us of the fable of the fox who had lost his tail. How accurately instinct works in the selection of the two systems is demonstrated by the fact that a succession of mild winters is always followed in the United States by an extended use of open grates; that is to say, the English system becomes, or tends to become fashionable, while, on the other hand, a succession of severe winters in this country brings at once into favour with builders and others a whole host of close stoves and similar devices which would not be looked at under more favourable conditions of the weather. While English winters remain moderately temperate, the open fireplace will enjoy the favour it deserves, as not only the most attractive, but the most scientific apparatus available for warming houses. (Engineer.)

Heat radiated from a fire passes through the air without increasing its temperature, in the same manner that the sunâ€™s rays in warming the earth pass through and leave the atmosphere at the higher altitudes so bitterly cold that water and even mercury will freeze: it is for this reason that open fires should be lighted some time before the apartment is required for use, so that firstly a glowing fire be obtained (flames do not radiate any material quantity of heat, and practically heat by contact only), and secondly the surrounding objects, walls, &c., be heated by radiation, and these in their turn warm the air.

In discussing the various methods of warming, it will be convenient to classify them under general heads.

To put the reader upon a more familiar basis with this subject, a short explanation of the cause of heat will be here given. Combustion is the chemical union of oxygen (contained in the air) with some other substance for which it has an affinity; as applied to coal, it is the combining of oxygen and carbon producing carbonic acid gas, and it is known to every one that all chemical combinations evolve heat.

Combustion may be said to be complete when coke, wood charcoal, or anthracite coal is burnt, as there is no smoke, the up current is colourless, and these fuels burn quite away, leaving nothing except a little ash, &c., which originally consisted of earthy impurities in the fuel. Ordinary coal contains bitumen (pitch) in its composition, which at a temperature of about 500Â° to 600Â° F., distils off as a smoky gas (carbon and hydrogen), but at a higher temperature this is ignited, forming flame by the union of oxygen with the smoke (carbon); the main principles of underfed, smoke-consuming grates are based upon this, with the object of causing all gaseous products from the fuel to pass through the incandescent portion of the fire and so render the consumption of the fuel complete, as will be explained later on.

A good authority says that â€œthe correct method of warming is to obtain everywhere, at will, the warmth most congenial to the constitution with air as pure as blows at the mountain top,â€ and it might have been added â€œwithout an unreasonable consumption of fuel.â€

Open Grate.â€”The ordinary open grate is too familiar to need any description, but it is wasteful of fuel to a degree that could only be tolerated in a mild climate where fuel was cheap. As a matter of fact, only some 10-12 per cent. of the heat generated in an open grate is utilised, the remainder going up the chimney. But this very fault is in one sense a virtue, in that it performs the ventilation of the apartment in an eminently satisfactory manner. By the addition of a contrivance for regulating the combustion in au open grate, the fuel consumption is much reduced, the combustion is rendered more perfect (diminishing or preventing smoke), the radiated heat is much increased, while the appearance of an open grate is retained, though it is in reality converted into an open stove.

It would not be out of place to explain the cause of draught. After a chimney has been used, the brickwork surrounding and forming it becomes warmed and retains its heat for a very considerable period even if no fire is lighted; this heat is slowly radiated, and warms the air contained in the chimney, rendering it lighter and causing it to rise and flow out at the top; this is immediately replaced by cold air from below, which is warmed and rises as before, and so continues, causing an up current of air to be passing through the flue, its swiftness varying with the heat. The more intense the heat produced by the fire, and the greater the height of the chimney, the more swift is the current of air known as the â€œdraughtâ€; and when once the draught is established it will remain for a very long time without any fire being lighted. A good draught is not to be despised, as can be certified by those who have suffered from the annoyance of a smoky chimney; yet too strong a draught is a disadvantage, as consuming the fuel too rapidly, robbing the fire and apartment of its heat, and causing draughts of another kind, which materially cool the room and tend to cause discomfort; this only applies to the old form of grate, as all or nearly all modern grates have a means of regulating the draught; even the common and old form of grate is provided with a â€œregisterâ€ or flap at the back, immediately over the fire (certainly not an economical position for it), through which the smoke passes into the chimney. This flap is provided with the view of having it full open to assist combustion when fire is first ignited, and afterwards partially closing it when fire is established, and so prevent undue loss of heat, but although this â€œregisterâ€ is provided with every stove of its kind,it has not, nor never has had, any means of regulating it. If the reader has one of these stoves in his residence, as most probably he has, for they are still used in the upper rooms of nearly every building, he can by a simple experiment experience the benefit of regulating this flap. By placing a piece of coal, or stone, or metal, with the tongs, after the fire is established, at the joint or hinge of the register, and then drawing the register forward and letting it rest, so that it is closed all but about 1Â½ in., it will be immediately found that one-fourth or one-third more heat is thrown into the room, for a similar result is brought about as with the modern projecting or overhanging brick backs, which cause the heat to be deflected forwards which would otherwise have passed directly up the chimney. If an existing stove of this description be fitted with a rack adjustment for the register flap and with an â€œeconomiser,â€ an advance of 30 to 40 per cent. in economy and comfort will be experienced, for in the ordinary manner in which these stoves are fitted and used, it can be taken that one-half the heat passes directly up the chimney; a good proportion of the heat radiated is drawn back by the current of air proceeding from the room towards and up the chimney; a proportion is lost by conduction, the heat being passed away to the walls and surrounding parts, and a fair proportion is lost by the smoke, which is really unconsumed fuel; but this form of stove is improving rapidly in various ways, as will be described hereafter.

Open Stove.â€”This subject has been most ably discussed by Dr. Pridgin Teale, in connection with the economising of fuel in house fires. His remarks will well bear repeating.

â€œIt is hardly possible to separate the two questions of economy of fuel and abatement of smoke. None who, in their own person, or as the companion or nurse of friends and relatives, have gone through the miseries of bronchitis or asthma in a dense London fog, can fail to perceive that this is a serious medical, not less than a great economical, question. Nine million tons of coalâ€”one-fourth of the domestic fuel consumption in this kingdomâ€”is what I estimate as a possible reward to the public if they will have the sense, the energy, and the determination to adopt the principles here advocated, and which can be applied for a very small outlay. Much has been said by scientific men about waste of fuel, and strong arguments have been advanced which make it probable that the most economical and smokeless method of using coal is to convert it first of all into gas and coke, and then to deliver it for consumption in this form instead of coal. Theoretically, no doubt, this is the most scientific and mostperfect use of fuel, and the day may come when its universal adoption may be possible. But before that time arrives many things must happen. The mode of manufacture, the apparatus on a mighty scale, and the mode of distribution must be developed, nay, almost created, and a revolution must be effected in nearly every fireplace in the kingdom. At present its realisation seems to be in a very remote future. Meantime I ask the public to adopt a method which is the same in principle, and in perfection not so very far short of it. It is nothing, more nor less, than that every fireplace should make its own gas and burn it, and make its own coke and burn it, and this can be done approximately at comparatively little cost, and without falling foul of any patent, or causing serious disturbances of existing fireplaces. We must, first of all, do away with the fallacy that fires wonâ€™t burn unless air passes through the bottom or front of the fire. The draught under the fire is what people swear by (aye, and many practical and scientific men too), and most difficult it is to sweep this cobweb away from peopleâ€™s brains. They provide 2 or 3 times as much air as is needed for combustion, â…“, perhaps, being the necessary supply of oxygen, the remainder serving to make a draught to blow the fire into a white heat, and to carry no end of waste heat rapidly up the chimney; â…” of cold air chilling the fire, â…” more than needful of cold air coming into the room to chill it; and much of the smoke and combustible gases hurried unburnt up the chimney. The two views which I am anxious to enforce upon the attention of the public, of builders, of ironmongers, and of inventors, are these: that the open grating under the fire is wrong in principle, defective in heating power, and wasteful of fuel, and that the right principle of burning coal is that no current of air should pass through the bottom of the fire, and that the bottom of the fire should be kept hot. This principle is violated by the plan of closing the slits in the grate by an iron plate resting on the grate, which cuts off the draught, but allows the chamber beneath the fire to become cold, and when cinders reach the plate they become chilled, cease to burn, and the fire becomes dead. The right principle is acted upon by the various grates with fire-brick bottoms, and the English public owes much to the inventor of this principle as carried out in the Abbotsford grates, which have done much to educate the British public in the appreciation of the fact that a fire will burn well with a current of air passing over it, and not through it. But there is a better thing than the solid fire-brick bottom, and that is a chamber underneath the grating, shut in from the outer air by a shield resting on the hearth and rising to the level of the bottom bar of the range. This hot-air chamber, into which fine ash can fall, produces on the whole a brighter and cleaner fire, and one which is more readily revived when low, than the solid fire-brick. There is another mighty advantage in the principle of the â€˜economiserâ€™â€”an unspeakable advantage, it is applicable to almost every existing fireplace, and it need not cost more than 3-4.sThis idea has now been long on its trial. It has been applied in hundreds of houses. It has been submitted to the very severe test of being applied to an infinite variety of grates, under a great variety of circumstances, and tried with coke, anthracite, and coal, good, bad, and indifferent. The effect has been, in an enormous number of instances, a marked success in saving coal and labour, and in more comfortable uniform warmth to the room. The failures have been very few indeed. I have drawn up 7 rules for the construction of a fireplace, all of which are pronounced to be sound:â€”

â€œ1. As much fire-brick, and as little iron as possible.

â€œ2. The back and sides of the fireplace should be fire-brick.

â€œ3. The back of the fireplace should lean or arch over the fire, so as to become heated by the rising flame.

â€œ4. The bottom of the fire or grating should be deep from before backwards, probably not less than 9 in. for a small room nor more than 11 in. for a large room.

â€œ5. The slits in the grating should be narrow, perhaps Â¼ in. wide, for a sitting-room grate, â…œ in. for a kitchen grate.

â€œ6. The bars in front should be narrow.

â€œ7. The chamber beneath the fire should be closed in front by a shield or economiser.

â€œThere is one caution which should be given. There is no doubt about the fact that immediately beneath the fire the hearthstone is hotter, and the ashes remain much hotter when the â€˜economiserâ€™ is used. This may increase the risk of fire whenever wooden beams lie under the fireplace. In any case of doubt, the best plan would be to take up the hearthstone and examine, and relay with safe materials; but should this be impossible, safety may be secured by covering the hearthstone with a sufficient thickness of fire-brick, just within the space enclosed by the â€˜economiserâ€™â€”leaving a space of 2 or more in. between the fire-brick hearth and the bottom of the fire. In lighting the fire, if there be no cinders on which to build the fire, it is well to draw away the â€˜economiserâ€™ for a short time until the fire has got hold; but, if there be cinders left from the previous day, on the top of which the paper and wood can be placed, then the fire may be lighted with the â€˜economizerâ€™ in its place. There is a great art in mending a fire. It is wasteful to throw lumps of coal higgledy-piggledy on the fire. The red embers should be first broken up so as to make a level surface, then pieces of coal should be laid flat on the fire and fitted in almost like pavement; lastly, if the fire is intended to burn slowly and last very long, small coal should be laid on the top. An â€˜economisedâ€™ fire so made will, in a short time, heat the coal through, and give off gases, which will ignite and burn brightly on the surface of the black mass, and when the gases are burnt off there is a large surface of red-hot coke.â€

30. Kitchen Economiser.31. Bedroom Economiser.

The annexed illustrations show the application of the economiser. Fig. 30 is a kitchen range,abeing the economiser andbthe front damper. The latter should always be used in warm weather, unless the front of the fire is needed for roasting and should be put on at night. Fig. 31 is a bedroom fireplace having fire-brick sidesa, fire-brick backbleaning over the fire, narrow front barscmovable, gratingdwithnarrow slits, chamber under the fire closed by economisere, and front damperfwhich can close the lower â…” of the front of the fire at night or when a slow fire is needed.

The â€œeconomiserâ€ is a shield of sheet iron which stands on the hearth, and rises as high as the lowest bar of the grate, against which it should fit accurately, so as to shut in the space or chamber under the fire. If the front of the range be curved or angular, as in most register stoves, the economiser will stand, owing to its shapeâ€”but if the front be straight, the economiser needs supports such as are shown. â€œOrdinary economisersâ€ are made of 16-gauge charcoal iron plate, with â…œ in. bright steel moulding at the top, Â½ in. moulding at the bottom, and 1 or 2 knobs as required. â€œKitchen economisersâ€ are made of 16-gauge iron, with Â½ in. semicircle iron at the top edge; and with supports in scroll form of Â½ in. semicircle iron. Some makers use rather thinner iron plate and give strength by the mouldings. Some have used too thin plates, little better than tin, which have warped and so become more or less useless. Great care should be spent in taking the dimensionsâ€”as every grate has to be measuredâ€”as a foot for a boot. This renders it almost impossible to send orders to a maker by post. Some skilled person must take the measure, and take it accurately. The dimensions to be taken are: firstly, the outline of the bottom bar of the grate. If it be curved, or angular, the outline can be well taken by a piece of leaden gas-pipe, which, moulded to the outline can then be traced upon paper or carried carefully away to the makers; secondly, the height must be measured from the hearthstone to the bottom bar. This is the â€œeconomiserâ€ in its simplest and cheapest form, as applicable to nearly every ordinary range.

Ornament can be added to taste. It is obvious that the adaptation of the economiser need not displace the old-fashioned ash-pan, and that the two can be combined, or that the economiser may be made like a drawer and catch the ashes. All such variations will work well, provided that the main principles be adhered to of â€œcutting off the under current,â€ and â€œkeeping the chamber under the fire hot.â€ But the simplest form is the best.

32. Some Modern Open Grates.

Fig. 32 illustrates a few typical specimens of modern improved open grates devised to increase the radiation of heat and perfect the combustion of the fuel: A is a combination of Parsonâ€™s grate and economiser with a Milner back; B is Nelson and Sonsâ€™ â€œrifleâ€ back; C is a Galton back; D, Jaffreyâ€™s grate.

â€œThe Manchester Warming and Ventilating Grateâ€ (E. H. Shorland, St. Gabrielâ€™s Works, Manchester) is somewhat similar in principle to Captain Galtonâ€™s grate, i.e. the warm fresh-air inlet is at the ceiling, and the vitiated air is carried off by the chimney, or in some instances ventilation at a lower part of the room is provided. Fig. 33 will acquaint the reader with the details:a, fireplace;b, outer wall;c, inner wall;d, smoke flue;e,f, cold-air inlets;g,h, warm-air passages;i, inlet for cold or warm air into room.

33. Shorlandâ€™s Manchester Warm-air Grate Back.

The shape of the back brick advocated by Dr. Teale (first invented by the celebrated Count Romford, to whom much is owing for the various means undertaken by him to promote the consideration of the question of improving our fire-grates and to abate the smoke nuisance) has since its discovery met with universal favour, and is coming into general use by all makers, as the expense of the stove is scarcely increased and its result in use is a most decided improvement. The actual shape or section of this brick varies with the different stove makers, but the result is the same; the brick is made to slope forward from the bottom up to about 15 or 16 in. high; at that height the top of the brick overhangs the bottom by about 5 to 6 in.; its section is appropriately defined by a maker, who likens it to a â€œdogâ€™s hind leg.â€ Some makers shape the brick like a curved scallop-shell, inclining forward at the top; the effect is that as the heat ascends from the fire, it strikes or comes in contact with the projecting part, and rebounds or is deflected into the room; it is a similar action to that which takes place if an object, say a ball, is thrown upon a wall and comes in contact with a similar projectionâ€”it would bound off or be deflected.

It would be impossible to describe all the existing improvements upon the ordinary or old form of open-fire stove (commonly known as a â€œregister grateâ€), but the following are some that are tolerably well known and have a good share of favour.

â€œThe Abbotsford Slow-combustion Grateâ€ (Mappin and Webb, Cheapside, London), which has now been used some years, was about the first recognised form of stove that had the bottom closed, so that the supply of air for combustion is carried through the front only. This is a great improvement (as explained by the economiser), by lessening the consumption of fuel without decreasing the efficiency or its heat-giving properties. The bottom of the fireplace is a solid fire-brick slab, and the chief property of this stove is truly named â€œslow combustion.â€ Many people have tried to apply thisadvantage to existing stoves by having a piece of iron cut to lieuponthe bottom grate; but iron is too rapid a conductor, and failure is experienced by having the lower part of the fire dull and dead. It cannot, however, be said that a solid bottom is the best, for it permits of accumulation of ash, and it is slow lighting.

34. Wharncliffe Grate.

â€œThe Wharncliffe Patent Warming and Ventilating Grateâ€ (Steel and Garland, 18 Charterhouse Street, London, E.C.) Fig. 34, is an excellent form of grate, and is fixed back against the wall, wholly projecting into the room, an air-chamber surrounding the fire-box; this air-chamber is, whenever convenient, connected with the outer air by means of a pipe, and within the chamber gills or ribs are provided, attached to the fire-box (the principle and advantages of these gills or ribs, which are to increase the heat-giving surface and to prevent over-heating of air, will be explained under Gill stoves).

When the fire is established, the metal of the fire-box becomes heated, which then heats the air contained in the air-chamber, rendering it lighter, whereupon it rises and flows out into the room through the perforations provided in the pattern of the ironwork; cold air immediately flows in to take its place, which is then heated, and passes out, so that as its name implies it is a ventilating as well as warming grate, and has the further advantage of the cheerful open radiating fire; but it must be remembered that with ventilating stoves there must be provision made for the removal of vitiated air, which in this case is taken up the chimney along with the products of combustion.

Another improved form of warming and ventilating grate is that invented by and named after Captain Douglas Galton (makers, Yates, Hayward & Co., Upper Thames Street, London). The principle advocated in this instance is contrary to that generally adopted, insomuch that the warmed fresh air is admitted into the room near the ceiling, and the abstraction of vitiated air is performed through the grate by the chimney draught. This is an open-fire grate fitted within a mantel in the usual way, and is provided with an air-chamber at the back, and which is connected with the outer air as before explained. From this air-chamber a perpendicular shaft or flue is carried, terminating by being turned into the room with an inlet grating or louvre. As before explained, the air within the air-chamber is warmed, and rises and passes into the room close to the ceiling; from there it is drawn down towards the fire, and eventually passes up the chimney, so that there is always a current of warm fresh air from the ceiling downwards. There are as many advocates for this down-current system as for the up current, as in the Wharncliffe and others. The Captain Galton has had about 14 yearsâ€™ trial, and is still largely used. A rather peculiar and advantageous action takes place, by the fact that the apartment becomes fully charged with fresh air and the supply for combustion and draught is not drawn from the crevices beneath doors, &c., sothat when a door is opened no inrush of cold air is experienced. This and the Manchester grate can most conveniently be used for warming another apartment also from the same fire.

35. Nautilus Grate.36. Nautilus Grate.

â€œThe Nautilus Grateâ€ (Jas. B. Petter & Co., Yeovil), Figs. 35 and 36, is, as the name signifies, shell-shaped. The products of combustion rise from the fire, and after revolving within the centre or axis pass off by two concealed flues at the back of the grate to a flue prepared in the back of the fireplace; the ashes fall through a small grating into a closed ash pan. The warmth radiated direct from the cheerful open fire and indirectly from the outer case is considerable, and the results are very satisfactory, as no heat is lost by conduction. This grate is also cleanly, economical, and portable. The back, cheeks, and hearth should be tiled; the extra expense is fully compensated for by the handsome appearance.

37. Eagle Convertible Grate.

The â€œIngle Nook,â€ Wrightâ€™s Patent (George Wright & Sons, 113 Queen Victoria Street, E.C.), Fig. 38, is a combination of all the most recent improvements, with two new features never before introduced into this class of grate, viz. the regulation ofdraught by means of an ordinary damper, and the complete independence of the actual working part of the stove, so that it may be removed at any time for repairs without disturbing the outer casing or brickwork.

Special features and advantages.

38. PLAN through line C.D.SECTION through line A.B.

Radiation and complete utilisation of the heat generated from all parts of the grate, as not only the heat given off from front of fire, but also all heat radiated from sides and back of grate, which is usually absorbed in brickwork, is here passed into warm-air chambers and thence into the room. Economy of fuel, with increase of heating power. Prevention of down-draught, and partial consumption of smoke. Simplicity of construction and fixing, so that easy access is afforded to all parts of the grate, more especially those likely to want renewing. Pleasing appearance of the ordinary open fire, with heating power of a warm-air stove. This stove being complete in itself can be fixed by any ordinary workman without removing the mantel-piece or in any way interfering with the decorations of the room. The whole construction and principle of the grate are so simple that they can be readily understood by reference to the plan and section annexed. The interior portion of fire-box is of fire-brick, and can readily be removed from the front without disturbing any other portion of the grate. The back leans forward, deflecting the radiant heat into the room, and contracts the throat of the flue so as to quicken the draught directly the fire is lighted, which flue then expands and is again contracted at the top by means of the damper. Less than half the quantity of fuel is required to warm any given space, and more than double the quantity of heat is given off than from an ordinary grate with the usual supply of fuel. By introducing a fresh-air flue where practicable the perfection of ventilation may be obtained. The cost does not greatly exceed that of an ordinary grate, and is very much below that of any other grate of this description at present in the market.See advertisement in front of title page.

â€œThe Rumford-Teale Grateâ€ (made by Verity Bros., 98 High Holborn, London), is made nearly wholly of fire-brick, upon strictly scientific principles, as the nameindicates. There is very little iron in its construction, the front being a steel wire trellis instead of bars; this permits free radiation from the front and reduces loss by conduction. This front, apparently fragile, lasts for a considerable time (4 or 5 years), and is easily replaced by any one at an extremely small cost.

An improvement upon the Rumford-Teale grate is the â€œEclat,â€ by the same makers, shown in elevation and section in Fig. 39. Its distinguishing features are a double flue (one for quick and the other for slow draught), and the projection of the fire in advance of the chimney breast. The figure shows:A, damper for regulating combustion;B, perforated fire-clay back;C, tiles to taste;D, economiser;E, ashpit;F, chimney breast;G, frieze;H, removable bottom grate with fine mesh;J, valve for regulating combustion.

There are several forms of combined open- and close-fire stoves, which stand independent of any brickwork, and are generally known as â€œAmerican stoves.â€ These stoves are good heat givers, ornamental, and have several advantages, and can be obtained at almost any hardware stores; they do not work upon strictly hygienic principles, as they are apt to get overheated when closed, and render the air unpleasantly dry; but this can be remedied to some extent by using a vaporising pan, as will be explained later on.

39. Ã‰clat Grate.Ã‰clat Grate.

There is another form of open-fire grate that should be mentioned, viz. those that have the fire replenished by placing the fresh fuel underneath, and are known as underfed smokeless grates. This idea, which deserves high commendation, has been rendered practical, but cannot be said to be perfected yet. It originated in Dr. Arnottâ€™s stove, which was made with the usual set of front bars fixed about 12 in. high from the hearth, and the space under the bars closed in front. The bottom of the fire, which is movable, is lowered down to the hearth and the space filled with coal: the fire is laid, and ignited on the top of this store of fuel. As the fire burns down, the bottom grating is raised by means of a lever bringing fresh fuel within the fire-basket, and this bottom is raised as often as the fire burns down; it will be seen that the gaseous products given off by the fresh fuel must pass through the incandescent fire, and so be perfectly consumed, and the space below the front bars is sufficiently large to hold fuel for one dayâ€™s consumption.

â€œThe Kensington Smoke-consuming Grateâ€ (Brown and Green, Finsbury Pavement, London) is an underfed grate, and has received high commendation from goodauthorities; it has not the complication of Dr. Arnottâ€™s, and is of good appearance, being fixed in a similar manner to any ordinary grate.

â€œHollandsâ€™ Patent Underfed Grateâ€ (Hollands & Co., Stoke Newington) is a still further improvement, and, except for a little complication in construction, may be considered the best in action and results. The advantages of underfed grates are, firstly, an abatement of the smoke nuisance, full utilisation of the fuel, and more powerful radiation from the top of fire, which is always incandescent. There is commonly no provision made for the supply of air for combustion, nor to replace that which is taken from the apartment by the draught in the chimneyâ€”the cracks and fissures around doors and windows sufficing for this purpose, is the too commonly general idea; but for perfection in warming upon hygienic principles, there must be a proper supply from external sources; but this will be more fully treated under Ventilation; it will, however, be noticed that some of the ventilating stoves make provision for this in themselves; this particularly applies to Captain Galtonâ€™s principle.

Close-Fire stoves.â€”The old form of close-fire warming and ventilating stove is that known as the â€œCockle.â€ It consists of a closed circular fire-box with a dome top and a similar shaped outer casing; between the fire-box and the casing is a space of a few inches all round, known as the air-chamber, which by means of a pipe is connected with the outer air. The action is similar to a flue; the air within the air-chamber, being in contact with the heated surface of the fire-box is warmed, and rises and flows out at the top through an aperture provided at the top (as explained with the Wharncliffe grate), or it is made with a nozzle at top to attach a pipe and carry the warm air wherever required, so making it a hot-air furnace, in which case it would be fixed in a basement or cellar as at the best it is not ornamental, but this primitive form of stove has gone somewhat into disuse.

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