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.
CHAPTER X.
ELECTRIC MESSAGES, ETC.
The telegraphic wire in the home and street will fulfil a very important part in the economy of the twentieth century. For conveying intelligence, as well as for heating, cooking and lighting, the electric current will become one of the most familiar of all the forces called in to assist in domestic arrangements. The rapidity with which the electric bell-push has taken the place of the old-fashioned knocker and the bell-hanger's system affords one indication of the readiness with which those forms of electric apparatus which are adapted to all the purposes of communicating and reminding will recommend themselves to the public during the twentieth century.