flue, into an adjoining chimney. The aim of the in-
ventor was to heat an extensive surface to about 200 de-
grees Fahrenheit, so as to diffuse a moderate warmth into
a room. He attains the power of keeping the heat at
this height by the valve for admitting air. When this is
opened widely, a large stream of air enters, and combus-
tion becomes active. When, on the contrary, the aper-
ture is reduced, a comparatively small stream is admitted,
and combustion languishes. The temperature of the
outer case is raised or depressed accordingly. By the
revolution of the heat and smoke round the division of
chambers, their power of giving forth warmth is expended
as far as possible on the plates of the outer case, so as to
be serviceable for the end in view; and it might be pos-
sible to exhaust the whole for that end by lengthening the
flue, or causing a great extent of it to pass through the
air of the room before entering the chimney. The Ar-
nott stove certainly makes the most economical use of
fuel of any species of contrivance for producing artificial
heat as yet known. Six pounds of Welsh coal or coke,
of the value of one penny, will serve an ordinary one for
a whole day.
The Arnott stove is capable of something nearly ap-bed. It was therefore made by many furnishing iro
proaching to self-regulation. When it was invented,
about 1834, there was in existence a well-known means
of adjusting the temperature of bakers' ovens by a self
acting thermometer. Though an old expedient, some
person had recently secured a patent upon it, a
Arnott was therefore unable to take advantage of it for
his stove. There are, however, many modes of produc-
ing the same curious mechanical results, and a few of
these he specifies. That which he has employed in the
stoves made under his own care, consists of a glass tube
inserted horizontally into the upper part of the heated
chamber of his stove, with a downward bend on the out
side. Mercury is put into the bend of this tube, leaving
the part which is within the stove empty of all but com-
mon air. This air, of course, expands in proportion to
the heat of the stove, and in doing so presses upon the
mercury in that part of the outer bend next to it. The
mercury in the other part of the bent tube accordingly
rises. A float on its surface is thus raised. Connected
with the float is a wire, which acts upon a valve at the
door of the fire-box, causing it to open and shut according
as the float falls or rises. By such simple means, the
least increase of heat within immediately and unavoidably
brings about a diminution of the supply of air to the fire,
which therefore instantly begins to burn less intensely.
So, also, any decrease of heat instantly produces a larger
supply of air, by which the fire is, as it were, poked, and
begins to burn more brightly. The cooling from a fresh
supply of coke must of course cause that increased supply
of oxygen which is necessary to make the new materials
glow; and the new and great heat thus brought about
must immediately check itself by the closing of the valve.
It is also obvious, that when the materials are nearly
burnt down, and the supply of air thus increased, the
only consequence is, that the air rushes in as long as
there is any thing to burn, and no longer.

kindling of ordinary fires. 4. No smoke, of the character
of the smoke of a common fire, arises from the stove,
but only a slight stream of volatile gases. 5. No dust
is diffused throughout the room. 6. The dangers to
which children, old people, and others, are exposed from
a common fire, are obviated. 7. The danger to property
is as little as the danger to persons.
8. The stove is
obedient to command, and could be managed by a child.
9. It can be established at little expense. 10. It saves
all expense for attendance. 11. It is easily moved. 12. It
may be fashioned into any graceful or convenient form,
so as to ornament a room. Dr. Arnott mentions that it
may be in the form of a statue. 13. A drawer inserted
into the heated chamber of the stove would serve for
cooking meat, and a pot for boiling might be placed upon
the fire-box; it is therefore, as Dr. Arnott remarks, pecu-
liarly the poor man's stove. 14. No sweeping-boys are
required.

Under a sense of professional honour, Dr. Arnott did not take out a patent for his stove. Regarding it as an invention for the improvement of health, he presented it to the world, as he had previously done his hydrostatic

The express advantages of the thermometer stove are enumerated by the learned inventor under fourteen heads, which we shall abridge. 1. Economy of fuel. While in the case of a common open fire, seven-eighths of the heat goes up the chimney, nearly the whole heat is secured by the stove. A gentleman known to us saw Dr. Arnott put a few leaves of a pamphlet into his firebox, the ignition of which immediately heated the whole stove, and diffused an agreeable warmth throughout the room. An ordinary room can be kept warm by the stove for twenty-four hours, at the expense of one penny in coke or anthracite. 2. The temperature diffused by the stove is uniform throughout the room. 3. The stove is always alight, to the saving of much of that inconvenience and loss of time occasioned by the going out and

mongers in the metropolis and elsewhere, some of whom took out patents for what they considered as improvements pupon it. Though the intention of the inventor was good, his liberality has had a bad result. The principle, simple as it appears, was not well understood. The stoves made by all, except a very few ironmongers, were constructed erroneously, the prevalent fault being a diminution of the heating surface in proportion to the strength of the furnace. It is a curious fact in science, well worthy of being noticed, that twelve patents were taken out in one year for modifications of the Arnott stove, all of which Dr. Arnott considered to be, upon false principles. The consequence has been that many Arnott stoves, which had been introduce into houses with a good hope of their acting beneficially, have been given up on account of the inconvenience felt from the species of heat which they generated. It is also, however, to be observed that the stove, made even upon the most approved principles, would require certain adjuncts and conditions in order to operate agreeably.

All metal surfaces, however well the principle of a large superficies moderately warmed may be observed, raise the temperature by two means, namely, by radiation and by conduction. Radiated heat, which is that given by a common fire, is perfectly safe; but the heat produced by the air coming in contact with a warmed surface is more or less deteriorated. The air, which forms the instrument or medium for heating the rest, has been altered in its character, particularly in being desiccated, or deprived of its humidity. It is necessary to counteract this result by an artificial infusion of humidity into the atmosphere. This may be done in various ways. The most common plan is to place a large open dish of water upon the stove; but in this case the evaporation does not proceed rapidly enough. It is better to keep a large wet cloth hanging near the stove. Perhaps the best possible arrangement is that consisting in a trough of water, with a roller moving in it, and a similar roller forming a windlass about two feet above. Between the windlass and the roller an endless piece of towelling revolves. The bottom of the piece of towelling passing, of course, through the water, it is only necessary to turn the windlass a few times in order to make the whole wet; and this process may be repeated as often as necessary. The vapour constantly arising from the cloth will, if sufficient in quantity, make good the want of humidity in the stove-heated air. Such an arrangement is necessary, not only in connection with the Arnott stove, but with Mr. Strutt's contrivances, and with all the modes of heating by warmed metal surfaces. We shall consider some further arrangements which such modes of

heating render necessary, under the head VENTILA- | empty, to save the risk of bursting by the expansion of

TION.

Hot-Water and Steam Apparatus.

In the hot-water and steam apparatus, the immediate ⚫ agent for heating is the same as in the Strutt and Arnott stoves, namely, an extensive metallic surface moderately heated. But the heating is in these cases effected by hot water and by steam respectively, and the arrangement and character of the warm surfaces are different.

Attic.

Drawing Rooin
Flor

the water. Fifteen per cent. of space is found by experience to be an ample allowance for the expansibility of the water. A compendious and readily understood specimen of the apparatus, calculated for a house of three stories, is presented in the accompanying engraving. It is important to observe that the pipe, while operating, is closed in every part, the air having been previously pumped out of it. The heat usually maintained is 180 degrees; but it can be increased to 400 degrees, where such is necessary, as it is, for example, in certain drying houses.

The hot-water apparatus has been fitted up by Messrs. Perkins and Heath in various public buildings, warehouses, and gentlemen's houses; and, while sufficiently effective for the desired end, it has been proved to be attended with as few drawbacks as any regulated mode of heating whatever. But there is a great obstacle to its general adoption in its expensiveness. If this difficulty were not insuperable, the plan, from the natural principles on which it is founded, could be applied very easily to several buildings at once, or even to a considerable part of a town-if not, indeed, to an entire city. From some central establishment, on a low level, where the heat was applied, there might proceed pipes to the various houses, in the same manner as the pipes from a gas-work. There would of course be a waste of heat in all those parts of the pipe which passed through streets and between one house and another; but this might be amply compensated by other economical features in the arrangement.

There is a variation of the hot-water apparatus, in which is made to take much of the form of Mr. Strutt's plan, a large coil of pipe in one hot-air chamber being the means of supplying warmed air to be distributed over the building. It has been exemplified at Coleshill, the mansion of the Earl of Radnor in Berkshire. The plan, in its ordinary form, has been applied also to vineries, conservatories, and forcing-houses, to which it must be considered as undeniably appropriate, if there be no objection on the score of expense.

The idea of warming rooms by pipes filled with hot water occurred to the Marquis de Chabannes, who first exemplified it in his own house in England. The plan has latterly been patented, and extensively acted upon by the ingenious copartnery of Perkins and Heath, London. It proceeds upon a simple law of heat, that particles of any fluid warmed above the temperature of those surrounding them, ascend. Thus, in a kettle of water upon a fire, the particles at the bottom are heated first, and immediately ascend to the surface, their place being instantly taken by cool particles from above, which again in like manner ascend as soon as heated; so that there is a constant flow of cool particles downward and warmed particles upward, until the whole are heated. The hot-water heating apparatus consists of a stout metal pipe, pervading the house in all the parts which are desired to be heated, having a valve at the top, and a coil at the bottom exposed to a furnace. This tube being filled with water from the top, and the fire being kindled in the furnace, warm particles begin to ascend, and are quickly felt at the very highest part of the pipe. Heating by steam-pipes is the only mode which reThe water heats gramains to be considered. It was suggested nearly a cendually from the top tury ago in the "Philosophical Transactions," but was downward, until the not for many years after reduced to practice. At length whole is warm. The it began to be introduced into factories, where a great pipe then gives off heat facility existed for its operation in the boilers connected to the surrounding atwith the steam-engines. As respects its power of heatmosphere. Such is the ing, and effect upon the surrounding air, it is identical principle. The arrangewith the plan last described, excepting only that the ment of the pipe may be surface of the pipes in this case can never be at a higher various: the plan genetemperature than 212 degrees. The size of the pipes rally followed is to place and other arrangements are considerably different. The a considerable coil of it following is an account of the apparatus fitted up on within a pedestal or this plan in the printing-office from which the present bunker, with open trellis work is issued:-"An iron tube, on which there is a work in front, in a concrane, carries the steam from the boiler to a connected venient part of the room. It may also be made to wind series of long tin pipes within the building. The diaround the room, behind the skirting-board, which, being meter of these tin pipes is about ten inches, and they perforated with holes, will allow of the entrance of the hang from the ceiling by means of small chains a few warmed air. The amount of pipe allowed to a room inches in length, so as to be quite clear of every article ought of course to bear a proportion to the size of the of furniture, and every head passing beneath. There is room, and other circumstances affecting its temperature. just one pipe going along each of the two lower stories The pipes are generally round, and from three to four in this manner; and from each a small waste pipe goes inches in diameter; but flattish pipes have sometimes outside to let off the waste steam and condensed water. been used. In the earlier stages of the history of the The pipes are varnished black, to cause the heat to raapparatus, a boiler was employed at the bottom for the diate freely from them. The whole apparatus is exceedheating of the water; but this was soon found to be at-ingly simple, and is managed with perfect ease. The tended with great danger, in consequence of the tendency of water in a tube to burst any vessel of capacity into which it may descend. The substitution of a coil of pipe was an improvement suggested by Mr. A. M. Perkins. At the top of the apparatus, the pipe expands into what is called the expansion tube, which is left

Ground Floor.

Furnace.

a Expansion Tube.
b Filling Tube.

and Justiciary Court Room in Edinburgh, are warmed upon
The British Museum in London, and the Register House
this plan.
Richardson's "Popular Treatise on the Warming and Ventila
A minute account of the hot-water plan is given in C.
tion of Buildings." 1839.

smallest turn of the crane permits the steam to rush through, and to fill the pipes, when an immediate radiation of heat commences. So effectual is the process, that if the steam be admitted only twice a day, for an hour at a time, the premises are kept in a state of the most agreeable warmth for the whole day. There can be no proper comparison betwixt this plan of heating and that of common fireplaces. Coal fires cannot warm the air in large workshops; they only heat the air in their own immediate neighbourhood; and hence the workmen are often obliged to draw near the grate to warm themselves. According to the plan we have adopted, every part of the house is equally heated, and the whole of the workmen are as comfortable during the hardest frosts as if they were working in a pleasant summer day. In consequence of this abundant warmth, all the fires have

person in the room. According to this view, the quan.
tity of steam-pipe or vessel needed, under the tempera-
tures supposed, for a room sixteen feet square by twelve
feet high, with two windows, each seven feet by three,
and with ventilation by them, or otherwise, at the rato
of sixteen cubic feet per minute, would be-
For 42 square feet of glass (requiring one foot for 6),
"1238 feet of wall, floor, and ceiling (requiring 1
foot for 120)

"16 feet per minute, ventilation (requiring 1 foot
for 6)

Total of heating surface required,

7

101

24

20

which is, twenty feet of pipe four inches in diameter, or any other vessel having the same extent of surface—as a box two feet high, with square top and bottom of about eighteen inches. It may be noticed that nearly the same quantity of heated surface would suffice for a larger ventilation, were not greater; for the extent of wall, room, provided the quantity of window-glass, and of the owing to its low conducting quality, produces comparatively little effect."

VENTILATION.

been withdrawn. It is difficult for us to say what is the probable expense of supplying the heat, seeing that we happen to draw our steam from a boiler which is always in operation for other purposes. We believe, however, that the expense of keeping up a necessary supply of steam for such an apparatus must be very small, perhaps not more than that for a single coal fire. Our apparatus cost about £80, and this sum will doubtless be saved in the course of a few winters. A similar plan of steamheating by means of cast-iron pipes is pursued in many In our article on the PRESERVATION OF HEALTH, the places, but we approve most of tubes of sheet tin soldered necessity of a constant supply of fresh air for that object together. Tin is light and cheap, and allows the heat at is so fully explained, and so earnestly insisted on, that once to operate, and, in case of explosion from improper on this occasion little more than an allusion to the submanagement, will rupture or give way without causing any ject is required. Each human being consumes the oxymischief; whereas iron is heavy and dear, takes long to gen of the sixth of a cubic foot per minute, replacing it heat, and in exploding would perhaps cause some injury. from his lungs by carbonic acid gas, a substance which Excellent, however, as is the process which we have mencannot be inhaled again without injury. Hence the netioned, we do not believe that it is calculated for private cessity for a constant change of the atmospheric condwelling-houses. In the first place, few domestic servants tents of any room in which human beings are placedcan be trusted with the management of any apparatus of this and the same law holds with regard to all the warmdescription, and this forms an almost insurmountable ob-blooded animals. In an ordinary apartment, heated by stacle to the general introduction of the process. Second- a common open fire, there is an imperfect kind of ventily, the pipes are clumsy, and therefore unsuitable for lation always going on by means of the fire, which draws passing through elegant apartments; and, thirdly, there in through the door, windows, and other apertures, fresh is at times a noise of the rushing of the steam in the air to supply that consumed by itself, or which the chimpipes, which would be quite insufferable in a private re-ney-draught otherwise carries off. This is imperfect, in sidence."*

To determine," says Dr. Arnott, "the extent of surface of steam-pipe or vessel necessary to warm particular apartments, it is to be considered that the loss of heat from them occurs in three ways-1st, rapidly through the thin glass of the windows; 2dly, more slowly through the thick substance of the walls, floor, and ceiling; and, 3dly, in combination with the air which escapes at the joinings of the windows and doors, or at other openings purposely made for ventilation. Different writers and manufacturers have made very different estimates of the quantities of heat lost in these various ways, and as yet no exposition of the matters has been made with the accuracy which the subject deserves; but an intermediate estimate, as applied to common cases, may be shortly stated thus:-that in a winter day, with the external temperature at 10 degrees below freezing, to maintain, in an ordinary apartment, the agreeable and healthful temperature of 60 degrees, there must be of surface of steampipe, or other steam vessel, heated to 200 degrees (which is the average surface temperature of vessels filled with steam of 212 degrees), about one foot square for every six feet of single glass window, of usual thickness; as much for every 120 feet of wall, roof, and ceiling, of ordinary material and thickness; and as much for every six cubic feet of hot air escaping per minute as ventilation, and replaced by cold air. A window with the usual accuracy of fitting, is held to allow about eight feet of air to pass by it in a minute, and there should be for ventilation at least three feet of air a minute for each

• Chambers's Edinburgh Journal, p. 319.

as far as the draught may only clear a certain space near the bottom of the room between the door or windows and the fireplace, and because it may over rarefy the air of the room in instances where the apertures are unusually well closed up-also, in as far as it only operates when there is a fire, and therefore not in the summer time. It therefore becomes desirable that a regulated mode of ventilation, calculated to be thoroughly and at all times effectual, should be applied to ordinary apartments. It is not less necessary that churches. court-rooms, theatres, and all large rooms in which great numbers of persons assemble, should be subjected to a mode of ventilation, regular, certain, and complete. Nor is it unworthy of notice, that a regular means of ventilation is also required in stables, cow-houses, and other places where valuable animals are kept.

VENTILATION BY APERTURES IN CEILINGS AND FLUES

IN WALLS.

The simplest and perhaps the earliest expedient for ventilation, was one formerly much employed in churches and other places of assembly. It consisted merely in a round hole of considerable size opened in the ceiling, and communicating with the outer air by a tube or trunk, having a cap over the top to keep out rain. The expired air of the assemblage, by virtue of its greater rarity, of course ascends to the ceiling, and tends to find its way out by this aperture; but it does not pass forth either rapidly or with certainty, and the plan is therefore to be considered as defective.

The plan adopted for carrying off used air in the Derby Infirmary, and other buildings warmed by Mr,

B

Strutt's plan, appears strikingly inferior in efficiency to the expedients for heating. The whole arrangement consisted in a flue from each room, terminating in the space under the roof, through which was a passage to the outer air, protected by a turn-cap. There cannot be, we apprehend, any certainty that such flues will act for the removal of used air.

Sir John Robinson of Edinburgh has exemplified Mr. Strutt's plans in his house in Randolph Crescent, with an ingenious improvement upon the ventilation flues. Having small fires in each room-for the purpose, mainly, of drawing the warmed air from its reservoir, the well of the staircase, into each apartment-he passes the ventilation flues close beside the ordinary smoke chimneys. The consequence is, that the heat of the smoke chimney is imparted to the ventilation flue, an upward current is established, and ventilation proceeds with certainty. This is a mode of ventilation which may be advantageously adopted in new houses, but could not easily be applied to those already built. In Sir John Robinson's house, the air of each apartment reaches the ventilation flue through a slit masked by the stucco-work upon the ceiling.

In many cases, it may be found expedient to adopt a simple mode of ventilation which was suggested by Dr. Arnott, and applied in Buckingham Palace. An aperture of from four to six inches is cut in the wall over the chimney, as near to the ceiling of the apartment as may be convenient. Into this is fitted a short metal tube, having a valve suspended at the extremity next to the apartment, and capable of opening inward to the chimney, but not in the other direction, by which means a return of smoke is prevented. This simple apparatus may be painted, or otherwise made ornamental. It operates by virtue of the draught in the chimney. When ever that is active from the presence of a fire, the valve is seen to open inwards, and a stream of air from the top of the apartment passes through into the chimney, and is carried off. The operation is precisely equivalent to the stream of air always passing into a chimney between the fire and the mantel-piece, but has the great superiority of draining off the most impure air in the room.

THE VENTILATING FAN AND pump.

moving like a pump in a square or round trunk. «Such a pump," says he, "answers not only for extracting foul air, but also for forcing in pure air where wanted. It may," he adds, “be fixed in position, or may be a mʊvable piece of furniture; to be used, for instance, to draw out air from the top of a window opened on a ball night, or from an opening in the wall concealed from view by a picture frame. By such a pump, air of perfect purity, and in any quantity, may easily be sent from any neighbouring situation, as from the top of a lofty tower, to supply a dwelling placed where unwholesome exhalations might enter by the doors and windows.

FIRE-DRAUGHT.

One of the most certain and effectual of all means of ventilation is that by fire-draught. It proceeds upon the simple principle that combustion demands a constant supply of air: a fire being placed in a certain convenient situation, and closed up from all supply of air excepting through flues communicating with the rooms to be ventilated, a flow of air out of those rooms is necessarily established, and this will proceed as long as the fire is kept burning. The plan has been exemplified with success in mines, where, a fire being lighted at the bottom of a shaft, air is drawn off in all directions around and sent up the shaft; to replace which, fresh air is constantly pouring down other shafts. There is one objection to fire-draught ventilation, that, in most circumstances, it requires both attention and considerable expense; but this might perhaps be overcome by a little ingenuity. There can at least be no doubt that, where established, it most completely answers the end in view, while it is equally true that in some situations there are means of arranging it in such a way as to require neither attention nor expense.

The plan has been exemplified during the last few years by Dr. D. B. Reid, first in his class-rooms in Edinburgh, afterwards in the temporary House of Cominons, and since then in various other structures, public and private. We shall endeavour to give an account of Dr. Reid's arrangements in the House of Commons, but deem it necessary first to advert to the plans of Mr. Joseph Fleming of Glasgow. Mr. Fleming originally contemplated ventilation in immediate connection with the objects of his profession (medicine), and in 1833 published a pamphlet on what he called a Disinfecting Apparatus, which he proposed to apply in hospitals and in beds for the sick generally. It consisted simply in tubes com

fire solely supported by air through those channels, so that any infectious virus arising from the patient's body was in every case carried off without coming in contact with those who stood near.

This is a piece of mechanism which has for many years been used in factories, to which it is particularly applicable from the readiness with which a mechanic power to keep it in motion can be obtained from the steam-engine. It is placed at the top of a flue, into|municating between the top or back of the beds and a which branches from all parts of the establishment proceed. Consisting simply of what its name imports, it only requires to be set in motion in order to draw off the air from every apartment communicating with it. Dr. Ure calculates that a steam-engine of one horse power will drive a fan which has equal effect with a draught produced by fuel equal to twenty horse power; in other terms, the economy of ventilation is to that by chimneydraught as 38 to 1. Of its efficacy there seems no room for doubt; but as yet there has been scarcely any attempt to show how it can be conveniently applied elsewhere than in factories. Dr. Arnott has shown pretty clearly that it has heretofore been used in a very uneconomical way, in consequence of ignorance. A far greater power has been in most cases applied than was strictly necessary, its constructors not being aware that air, like other fluids, cannot be forced more quickly through one part of a passage than it enters by another, without a super-expenditure of force. Under judicious arrangements, Dr. Arnott thinks that fans which have required steamengines to drive them, might be made to operate by a weight no greater than that required for a large clock. He seems, however, to prefer to the fan a valved piston

Architectural Magazine.

The plan was first tried in a large and densely peopled house which had long been remarkable as a focus of fever infection, in consequence of the wretchedness and filth of the inhabitants, and the narrow space allotted to them. This building, usually called from its size and appearance the Barracks, was connected with the factory of Messrs. Houldsworth and Son in Anderston, a suburb of Glasgow. It was divided into a multitude of small apartments, each consisting of a single room and closet, and each devoted to the accommodation of a single family. The total amount of inhabitants is rarely under 500. We have inspected this building, and can testify that the habits of the occupants, with a few exceptions, are of that uncleanly and ill-ordered character which naturally results from a mode of life in which housewifely economy is not a part of female education. Many of the inhabitants, it may be added, are Irish. The huddling of so many human beings into such small space, joined to filth, poverty, and intemperate habits, rendered the building, up to 1832, the permanent abode of pestilential disease. Five have been seen ill with