The enormous waste involved in the common methods of heating is one of the principal defects of household economy which will be corrected during the twentieth century. Different authorities have made varying estimates of the proportion between the heat which goes up the chimney of an ordinary grate, and that which actually passes out into the room fulfilling its purpose of maintaining an equable temperature; but it cannot be denied that, at the very least, something like three-fourths of the heat generated by the domestic fires of even the most advanced and civilised nations goes absolutely to waste—or rather to worse than waste—because the extra smoke produced in creating it only serves to pollute the atmosphere. In the cities some degree of progress has been made in the introduction of heating appliances which really give warmth to a room without losing at least seventy-five per cent. of their heat; but in the country districts, where open fireplaces are the rule, it is not unusual to find that more than ninety per cent. of the heat produced behind the domestic hearth goes up the chimney.

Sentiment has had a great deal to do with retarding progress in the direction of improved house-heating appliances. For countless ages "the hearth" has been, so to speak, the domestic altar, around which some of the most sacred associations of mankind have gathered, and popular sentiment has declared that it is not for the iconoclastic inventor or architect to improve it out of existence, or even to interfere seriously with either its shape or the position in the living room from which it sheds its genial warmth and cheerfulness around the family circle. A recognition of this ineradicable popular feeling was involved in the adoption of the grate, filled with glowing balls of asbestos composition, by the makers of gas-heating apparatus. The imitation of the coal-filled grate is in some cases almost perfect; and yet it is in this close approximation to the real article that some lovers of the domestic fuel-fire find their chief objection, just as the tricks of anthropoid animals—so strongly reminiscent of human beings and yet distinct—have the effect of repelling some people far more than the ways of creatures utterly unlike man in form and feature. Taking count of the domestic attachment to a real fuel-filled fireplace or grate as one of the principal factors in the problem of domestic heating, it is plain that one way of obviating the waste of heat which is at present incurred, without doing violence to that sentiment, is by making better use of the chimney. The hot-air pipes and coils which are already so largely used for indoor heating offer in themselves a hint in this direction. Long pipes or coils inserted in the course taken by the heated air in ascending a chimney become warm, and it is possible, by taking such a pipe from one part of the room up the passage and back again, to cause, by means of a small rotating fan or other ventilating apparatus, the whole of the air in the chamber to circulate up the chimney and back again every few minutes, gathering warmth as it goes. In this way, and by exposing as much heating surface to the warm air in the chimney as possible, the warmth derived by an ordinary room from a fuel fire can be more than doubled.

At the same time the risk of spreading "smuts" over the room can be entirely avoided first by keeping the whole length of pipe perfectly air-tight, and attaching it in such a way as to be readily removed for inspection; and, secondly, by placing the outward vent in such a position that the gentle current must mount upwards, and any dust must fall back again into a wide funnel-shaped orifice, and by covering the latter with fine wire gauze. An apparatus of this kind acts as a remover of dust from the room instead of adding any to it. One necessity, however, is the provision of motive power, very small though it be, to work the fan or otherwise promote a draught.

Electric heating is, however, the method which will probably take precedence over others in all those cases where systems are tried on their actual merits apart from sentiment or usage. The wonderful facility afforded by the electric heating wire for the distribution of a moderate degree of warmth, in exactly the proportions in which it may be needed, gives the electric method an enormous advantage over its rivals. The fundamental principle upon which heating by electricity is generally arranged depends upon the fact that a thin wire offers more electrical resistance to the passage of a current than a thick one, and therefore becomes heated. In the case of the incandescent lamp, in which the carbon filament requires to be raised to a white heat and must be free to emit its light without interference from opaque matter, it is necessary to protect the resisting and glowing material by nearly exhausting the air from the hermetically sealed globe or bulb in which it is enclosed.

But in electrical house-warming, for which a white heat is not required and in which the necessary protection from the air can be secured by embedding the conveying medium in opaque solid material, the problem becomes much simpler, because strong metallic wires can be used, and they may be enclosed in any kind of cement which does not corrode them and which distributes the heat while refusing to conduct the electric current. A network of wire, crossing and recrossing but always carrying the same current, may be embedded in plaster and a gentle heat may be imparted to the whole mass through the resistance of the wires to the electricity and their contact with the non-conducting material.

Concurrently with this method of heating there is gradually being introduced a practice of using metallic lathing for the plastering of dwelling-rooms in place of the old wooden battens generally employed for lath-and-plaster work. The solution of the practical problem which has to be faced seems to depend upon the prospect of effecting a compromise between the two systems, introducing thin resisting wire as the metallic element in such work, but making all other components from non-conducting material. In the event of any "cut-out" or "short-circuiting" occurring through accidental injury to the wall, it would be very inconvenient to be compelled to knock away the plaster. Moreover, it is not necessary for ordinary warming purposes that the whole of the wall, up to the ceiling, should be heated.

Accordingly the system which is likely to commend itself is that of constructing panels on some such principle as the one already described, and affixing them to the wall, forming a kind of solid dado from three to four feet from the floor. These can be fastened so as to facilitate removal for examination and repairs. When the current is switched on they are slowly warmed up by the heat generated through the resistance of the wires, and the air in the room is gently heated without being vitiated or deprived of its oxygen as it is by the presence of flames, whether of fuel or of gas. Warming footstools will also be provided, and a room heated in this way will be found eminently comfortable to live in.

This method of house-warming having once obtained a decided lead within the cities and other localities where a cheap electric current is available, somewhat similar systems, adapted for the heating of walls by hot air in tubes, instead of by resistant wires, will be largely adopted in the rural districts, more particularly in churches and other places of public assemblage. The progress made in this direction during the last few years of the nineteenth century is already noteworthy, but when electric-heating really gets a good chance to force the pace of improvement, the day will soon arrive when it will be regarded as nothing less than barbarous to ask people to sit during the winter months in places not evenly warmed all through by methods which result in the distribution of the heat exactly as it is wanted.

Ventilation is another household reform which will be very greatly accelerated by the presence of electric power of low cost. The great majority of civilised people, as yet, have no idea of ventilation excepting that highly unreasonable kind which depends upon leaving their houses and other buildings partly open to the outside weather. One man is sitting in church under a down draught from an open window above him, while others, in different parts of the same building, may be weltering in the heat and feeling stifled through the vitiated air. In dwelling-houses the great majority of living rooms really have no other effective form of ventilation than the draught from the fireplace. The strength of this draught, again, is regulated to a very large extent by the speed and direction of the outside wind.

In calm and sultry weather, when ventilation is most needed, the current of air from the fireplace may be very slight indeed; while in the wild and boisterous days succeeding a sudden change of weather, the living rooms are subjected to such a drop in temperature and are swept by such draughts of cold air that the inmates are very liable to catch colds and influenza. Hence has arisen in the British Islands, and in the colder countries of Europe and America, the very general desire among the poorer classes to suppress all ventilation. Rooms are closed at the commencement of winter and practically remain so until the summer season. Many people whose circumstances have improved, and who pass suddenly from ill-ventilated houses to those which have better access to the outside air, find the change so severe upon their constitutions and habits that they give a bad name to everything in the shape of ventilation. Meanwhile the dread of draughts causes people to exclude the fresh air to such an extent that consumption and many other diseases are fostered and engendered.

All this arises mainly from the very serious mistake of imagining that it is possible to move air without the exercise of force. In the case of the draught caused by a fire no doubt an active force is employed in the energy of the heated air ascending the chimney, and in the corresponding inrush. This latter is usually drawn from below the door—the very worst place from which it can be taken, seeing that in the experience of most people it is by getting the feet chilled, through draughts along the floor, that the worst colds are generally contracted. Fireplaces are not unusually regarded as a direct means for ventilation, and with regard to nearly all the devices commonly adopted in houses and public buildings, it may be said that they lack the first requisite for a scientific system of renewing the air, namely a source of power by means of which to shift it from outside to inside, and vice versÂ. There is no direction in which a more pressing need exists for the distribution of power in small quantities than in regard to the ventilation of private and public edifices.

The circular fan, placed in the centre piece of the ceiling and controlled by an electric switch on the wall, is the principal type of apparatus applicable to the purposes of ventilation. As electric lighting of dwelling-houses becomes more common, and ultimately almost universal within cities, the practice will be to arrange for lighting and for ventilation at the same time. But, unfortunately, the current now principally employed for electric lighting and consisting of a series of impulses, first in one direction and then in the opposite, "alternating" with wonderful rapidity, is not well adapted for driving small motors of the types now in use. One improvement in domestic economy greatly needed in the twentieth century consists in the invention of a really effective simple and economical "alternate-current" motor. This is a matter which will be referred to in dealing with electrical machines. That the problem will be solved before many years have passed there is no good reason to doubt.

In the meantime many laudable endeavours are being made towards the application of the pressure from water pipes to the purpose of driving ventilating fans. The extreme wastefulness of power and of water involved in this method of dealing with the difficulty may be partially overlooked on account of the very small amounts required to produce an effect in the desired direction; and yet there is no doubt that a recognition of the wastefulness acts to some extent as a deterrent to artificial ventilation. The benefits of the system are not sufficiently obvious or showy to induce any class of people, excepting physicians and persons fully acquainted with the principles of hygiene, to sanction a material outlay upon the object. When an exactly suitable alternate-current motor has been invented the standard electric light installation will be practically one apparatus with the ventilating fan, and the cost of the latter will hardly be felt as a separate item.

In cooking there is in existing ordinary methods the same enormous waste of heat as there is in the warming of rooms. Something, no doubt, has been done in the direction of economy by the invention of new and improved forms of stoves, but a great preponderance of the heat generated in the fire of even the best stove goes up the chimney. The electric oven, as already invented, is perhaps the nearest approach to a really economical "cooker" that has yet been proposed; but even before the general adoption of such an apparatus there will be ample room for improvement in the cooking stove, first as regards insulation, and secondly in the distribution of the fuel around the objects to be heated. One principal cause of the waste that goes on arises from the fact that the fire burns away from the place at which its heat is most beneficially applied, and no means are adopted, as in the case of the candle in a carriage lamp, for keeping it up to the required level. Additions of fuel are made from the top with the immediate effect of checking the heat.

A great advance in economy of fuel will take place when the household coal intended for cooking purposes is ground up together with the proper proportions of certain waste products of chemistry, so as to make a "smouldering mixture" which can be kept regularly supplied to a shallow or thin fire box by pressure applied from beneath or at the parts farthest away from the objects to be heated. An oven, for instance, may be surrounded by a "jacket" filled with ground smouldering mixture having a non-conducting insulator outside and a connection with a chimney. The heat from the fuel is thus kept in close proximity to the objects requiring to be cooked, and comparatively small waste results.

It is by taking advantage of their superior facilities in the same direction that gas and inflammable oils have already made their mark in the sphere of domestic cookery. Regarded as fuel their initial cost may be relatively heavy; and yet, owing to their more exact method of application, they often effect a saving in the end. Not only do they bring the fire closer to the articles to be heated or cooked, but they also make it easy for the fire to be turned off or on, and this in itself is an important source of economy. Still, with the advent of cheaper and more accessible power in every centre of population, the cost of grinding coal and of mixing it in order to form a fuel comparable in respect of convenience and economy with gas and oil will be so greatly reduced that the "black diamond" will still continue to challenge its rivals in the arena of competition presented by the demands of domestic economy.

Light, as well as heat and air, requires to be evenly and equably distributed throughout the dwelling-house before anything approaching an ideal residence can be secured. As the science of hygiene advances it is demonstrated more and more clearly that sunlight—and even diffused daylight—may be used as a most effective weapon against the spread of disease. Alternations of deep gloom in the dwelling-house with the superior light resulting from brighter weather produce many kinds of nervous derangement, not the least deleterious of which arise from the unnecessary strain to which the eyesight is subjected. The promise of the future is that, through the abundance of windows provided in the walls, roofs and porches of our dwelling-houses—but all supplemented with shutters and blinds of various kinds—there shall be a possibility of regulating, far more accurately than at present, the accessibility of light from outside according to the brightness or dulness of the day.

It is hardly to be expected that many people will build "Crystal Palaces" in which to reside; but with the immense progress that is being made in the construction of dwellings with iron or steel frames, and in the adaptation of various materials so that they may serve for building purposes in conjunction with metallic frameworks, it seems clear that many roofs, as well as large portions of walls, will in future be made on the composite principle, using steel and glass. These will, to a large extent, be permanently sheltered from the direct rays of the sun when high in the heavens, by shutters constructed on the louvre principle so that they may admit the light from the sky continually, but actual rays or beams of sunlight only for a short time after sunrise and at the close of day. The ceilings, if any are provided under the roofs, will also be glazed.

The obstacles presented in the way of such a reform in a city like London may at first sight seem so serious as to be practically insuperable. Long rows of three or four storied houses certainly offer but few facilities for the admission of light through the roofs of any but the rooms on the top floors, and yet it is in the dwelling-houses of this type that the depression caused by gloom and the absence of light during the hours of day are most severely felt as a source of nervous depression. Evolution in a matter of this sort will take place gradually and along the line of least resistance. Portions of courts, areas and yards will be glazed over in the way described; and it will be found that those rooms which are thus enclosed and sheltered from the wind and rain, but left open to the daylight, constitute the most cheerful sitting places in the houses. Then, as rebuilding and alterations proceed, many houses will gradually be remodelled—at least as regards some of their rooms—in the same direction. Physicians will become increasingly insistent on the necessity for admitting plenty of light into the abodes of the sick, more particularly of families inclined towards consumption.

A very large trade will spring up during the twentieth century in household cooling apparatus for use in hot climates. The colonial expansion towards which all European races are now tending inevitably means that very many thousands of persons whose ancestors have been accustomed to life in cold or temperate climates, will be induced to dwell in the dry and warm, or in the humid tropical regions of the earth. It will be an important task of the British, Continental and American machinists of the twentieth century to turn out convenient pieces of apparatus which shall be available for ventilating houses, especially during the night, and for reducing the temperature in them to something approaching that which is natural to the inmates. The old clumsy punkah will be replaced by circular fans keeping up a gentle current of air with a minimum of noise or annoyance of any kind.

At present it is only in specially favoured circumstances that these quiet-working circular punkahs can be actuated by mechanical force, that is to say where a prime motor, or an electric current, or a reticulated water supply for driving a suitable machine may be at hand. In other situations the use of compressed air or gas may be resorted to, and for this purpose small capsules, similar to those already introduced for making soda water by the liberation of compressed carbonic acid gas, will be found handy. For a very small sum of money the householder will be able to purchase a sufficient number of capsules to ensure motive power for his fan during a week of hot nights.

A convenient form of small motor suitable for being driven by compressed air or gases in this way is one in which a diminutive turbine or other wheel is set at the bottom of a thin tube of mercury. The capsule, being fastened to the lower end of this apparatus, liberates at very short intervals of time bubbles of air or gas, which, in the upward ascent, drive the wheel. The arrangement depends upon the fact that a stream of gas ascending in a heavy liquid behaves in the same way as a stream of water descending by its own weight and turning a water-wheel. It supplies what is perhaps the simplest and most inexpensive small motor available for the lightest domestic work to which a gentle but continuous source of power is applicable.

For actually cooling the air, as well as keeping it in motion, similar devices will be resorted to, with the addition of the circulation of the current of air through coils of pipes laid under the surface of the ground. In this way householders will have all the advantages of living in cool underground rooms without incurring the discomforts and dangers which are often inseparable from that mode of life. In the coastal regions, which usually have the most trying climates for Europeans living in tropical countries, a method of cooling the houses will be based on the fact that at moderate depths in the sea the prevailing temperature is a steady one, not much above the freezing point of water. Almost every seaport town within the tropics—where white residents in their houses swelter nightly in the greatest discomfort from the heat—is in close proximity to deep ocean water, in which, at all seasons of the year, the regular temperature is only about thirty-four degrees Fahr. The cost of steel piping strong enough to withstand the pressure of the water in places which possess absolutely the coolest temperature of the ocean would be very heavy; but, on the other hand, the actual reduction of heat demanded for the satisfactory cooling of the air in a dwelling-room is not by any means great, and at quite shallow depths the heat of the air can be satisfactorily abstracted by the sea water surrounding coils of pipes.

Even in colder climates it seems likely that similar systems will be found useful in producing a preliminary reduction in the temperature of the air employed in keeping fresh foodstuffs such as meat, fruits and vegetables. Fruits especially, when placed in suitable receptacles, and stored at temperatures quite steady at about the freezing point of water, will not only be readily kept on land from one season to another, but will be transported to markets thousands of miles distant from the growers, and sold in practically the same condition as if they had just been picked from the trees. During the twentieth century the proportion of the fruit eaters among the peoples of the great manufacturing countries will be very largely augmented, and this result will be brought about mainly through the instrumentality of methods of keeping perishable produce free from deterioration by maintaining it almost at the freezing point—a temperature at which, under suitable conditions as regards exclusion of moisture, and steadiness of hygrometric pressure, the germs of decay in food are practically prevented from coming to maturity.

For the cooling of dwelling-rooms in places distant from the sea, various systems, depending upon the supply of dry cold air from central stations through pipes to the dwellings of subscribers, will no doubt be brought into operation. This, however, will only be practicable in the more populous localities having plenty of residents ready to contribute to the expense. For more isolated houses the cooling and ventilating apparatus of the future may be a modification of the "shower-blast" which has been successfully adapted to metallurgical purposes. When downward jets of water, as in a shower-bath, are enclosed in a large pipe connected horizontally with a room but having facilities for the escape of the water underneath, a strong draught of cool air is created, and the prevailing temperature is quickly reduced. An apparatus of this kind may be intended for application either to the ventilators or to the windows of rooms.

Lifts for conveying persons from one storey of a building to another will probably undergo a considerable amount of modification during the next few years. The establishment of central electric stations and the distribution of electricity for lighting and for power will offer a very great premium upon the preference for electric motors for lifts. As soon as a maximum of efficiency, combined with the minimum of cost, has been attained, there will be a demand for the introduction of lifts in positions where the traffic is not large enough to warrant the constant presence of an attendant. In fact the desire will be for some kind of elevator which shall be just as free to the use of each individual as is the staircase of an ordinary house.

For this purpose, inclined planes having moving canvas or similar ramps will be extensively brought into use. The passenger steps upon what is practically an endless belt having suitable slats upon it to prevent his foot from slipping, and, as the hand-railing at the side of this moves concurrently, he is taken up, without any effort, to the landing on which he may alight quite steadily. When this idea, which has already been brought into operation, has been more fully developed, it will be seen that a large circular slowly-revolving disc, set at an angle and properly furnished, will supply a more convenient form of free elevator. One side will be used by those who are going up and the other by those who wish to come down. The "well" of the staircase for such a lift is made in elliptical form, like the shadow projection of a circle. Steps can be provided so that, when not in motion, the lift will be a staircase not differing much from the old style.