CHAMBERS'S INFORMATION FOR THE PEOPLE. 



When steam enters a cold vessel, it is condensed 

 into water, and, at the same time, gives out its 

 latent heat till the vessel is raised to 212, when 

 the condensation ceases. The condensing vessel 

 is usually a cast-iron pipe placed round the wall 

 of the apartment near the floor. In admitting 

 fresh air into the room, it may be made to pass 

 over this pipe, and thus be wanned. The steam 

 is conducted from the boiler by a smaller tube, 

 which may be covered with list or other material, 

 to prevent all condensation by the way ; and the 

 admission of the steam is regulated by a cock 

 within the apartment, means being provided for 

 allowing the air to escape. Where a pipe cannot 

 be laid round the room, a coil of pipe may be 

 formed, or the steam may be admitted into a large 

 vessel or into a hollow statue, forming a steam- 

 stove. Allowance must be made for the expansion 

 of the tubes by heat ; and they are so arranged 

 that the condensed water is conveyed back to the 

 boiler. One round of iron pipe, of 4 inches 

 diameter, is quite sufficient to warm each of the 

 large apartments or stories of the printing-office 

 from which the present work issues. It is diffi- 

 cult to estimate the expense of supplying the heat, 

 seeing that the steam happens to be drawn from 

 a boiler which is always in operation for other 

 purposes. Excellent, however, as the process is, 

 it is for many reasons unsuited to private dwelling- 

 houses. 



In calculating how much surface of steam-pipe 

 will be sufficient to warm a room, it is customary 

 to allow about i foot square for every 6 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 6 cubic feet of hot air escaping per minute 

 as ventilation, and replaced by cold air. 



Hot Water. Hot-water apparatus was applied 

 as early as 1777 by M. Bonnemain, in Paris, to 

 warm the hot-houses at the Jardin des Plantes, as 

 well as for the artificial hatching of chickens. It 

 was first introduced into England by the Marquis 

 de Chabannes in 1816, and is now used in many 

 large buildings. It is more economical than 

 steam, except where a steam-boiler is required for 

 machinery ; and from this and other advantages, 

 it is generally preferred to steam-apparatus. One 

 of these advantages is, that the heat begins to be 

 distributed, in some degree, as soon as the fire is 

 lighted, while with steam-apparatus the whole of 

 the water must be at boiling-heat before any steam 

 enters the pipes. 



There are two kinds of hot-water apparatus 

 high-pressure and low-pres- 

 sure. In the first, the water 

 is confined, and can be heated 

 to any degree ; in the other, 

 it is open to the air, and can- 

 not be heated above 212. 

 Fig. 3 will explain the way 

 in which water is made to 

 carry the heat of a furnace 

 to any part of a building on 

 the low-pressure principle, a 

 is a boiler, from the top of 

 which a tube issues, and, after 

 circulating through the build- 

 ing, re-enters near the bottom. At the top of 

 the circuit there is a funnel, or a small cistern, 

 c. by which the tubes and boiler may be kept full. 



486 



Fig. 3- 



When the fire is lighted at the bottom of the 

 boiler, the heated portion of water, being lighter 

 than the rest, rises towards the top through 

 the tube, bb, while the colder water from dd 

 flows in to take its place. The tube is made 

 to traverse the apartments to be warmed, where 

 it gives out its heat to the air; the returning 

 portion of the pipe is thus always colder, and 

 therefore heavier than the other, so that the 

 circulation is constantly kept up. The warming 

 surface is increased, wherever it is necessary, by 

 coiling the pipe, or by making expansions upon 

 it of various forms, so as to constitute water- 

 stoves. 



To avoid the necessity of so large a surface, and 

 such a mass of water as is required at the low 

 temperature the water attains in the pipes of this 

 kind of apparatus, Mr Perkins introduced the high- 

 pressure system. In 

 this the pipe is made 

 comparatively small, 

 but very strong, and 

 is formed into an 

 endless circuit cut off 

 from the atmosphere. 

 The water is heated 

 by making a number 

 of coils of the pipe 

 itself pass through 

 the furnace ; and as 

 the whole circuit 

 forms a shut vessel 

 as it were, the tem- 

 perature may be 

 raised to 300 and 

 upwards, according 

 to the strength of the 

 pipes. This high 

 temperature causes 

 a rapid circulation. 

 A compendious and 

 readily understood 

 specimen of the ap- 

 paratus, calculated 

 for a house of three 

 stories, is presented 

 in the accompanying 

 engraving. In filling 

 the tube with water, 

 which enters at b, 

 care is taken to expel 

 all the air ; and at a 

 there is an expansion 

 of the tube, equal to 15 or 20 per cent, of the 

 capacity of the whole, which is left empty both of 

 water and air, to allow for the expansion of the 

 water when heated. The arrangement of the pipe 

 may be various : the plan generally followed is to 

 place a considerable coil of it within a pedestal or 

 bunker, with open trellis-work in front, in a con- 

 venient part of the room. It may also be made to 

 wind round the room, behind the skirting-board, 

 which, being perforated with holes, will allow of 

 the entrance of the warmed air. 



This hot-water apparatus is fitted up in various 

 public buildings, warehouses, and gentlemen's 

 bouses; and, while sufficiently effective for the 

 desired end, it has been proved to be attended 

 with as few drawbacks as any regulated mode of 

 dealing whatever. But there is a great obstacle 

 to its general adoption in its expensiveness. The 



