CHAMBERS'S INFORMATION FOR THE PEOPLE. 



to become flame, and so to augment the blaze. 

 When the cinder is once fairly ignited, all the 

 bitumen rising through it afterwards burns, and 

 the fire remains smokeless.' 



As there is no supply of air but through the bars 

 in front, the box being close underneath, the fire 

 must be gradually raised up as the combustion 

 goes on ; and this is effected by having a false 

 bottom, ss, in the box, which can be moved like a 

 piston by means of a rod. The rod has notches 

 in it, and, by means of the poker used as a lever, 

 can be raised up and then retained at any height 

 by a ratchet-catch. 



' A remarkable and very valuable quality of this 

 fire is, its tenacity of life, so to speak, or its little 

 tendency to be extinguished.' Even after it sinks 

 below the level of the box, it does not go out, but 

 continues to smoulder slowly for a whole day or 

 night, and is ready to burn up actively when the 

 piston is raised. 



Another peculiarity of the Arnott grate is the 

 means taken to diminish the proportion of the 

 heat usually carried up the chimney. Of the thick 

 column of smoke that issues from a common 

 chimney-can, only a small fraction is true smoke 

 or burned air ; the rest consists of the warmest air 

 of the room, which becomes mixed with the true 

 smoke in the large space usually left between the 

 top of the fire and the throat of the chimney. 

 To remedy this evil is the object of the hood of 

 metal, yab, in the diagram, which prevents the 

 entrance of pure air to mix with the smoke. The 

 saving of fuel in this way is said to be from one- 

 third to one-half. 



The hood is furnished with a throttle-valve or 

 damper, /, having an external index, shewing its 

 position, so as to give complete control over the 

 current. The provision made for ventilation in 

 this fireplace will be considered in another part of 

 the paper. 



Even in this, perhaps the most economical form 

 of open fire yet contrived, there is still great waste 

 of the heat actually produced by the combustion. 

 To say nothing of what passes by conduction from 

 the fire itself into the wall, and is mostly lost ; the 

 quantity carried off in combination with the hot 

 gases, though no more air is allowed to enter than 

 is necessary for complete combustion, is still great. 

 It deserves being noticed, that the proportion thus 

 carried off is greatest in the case of fuel that burns 

 with flame. Experiment shews that a fire of wood 

 radiates one-quarter of its heat, the rest flying up ; 

 while the radiation from wood-charcoal is one-half 

 of the whole heat produced. Every one has felt 

 that a blazing fire has far less warming effect than 

 a glowing one. Not that flame has not intense 

 heat in it more intense even than a glowing fire ; 

 but it gives it out only by contact, and not by 

 radiation. It thus appears that any mode of heat- 

 ing that depends upon direct radiation, as the 

 open fireplace chiefly does, necessarily involves 

 great waste of fuel. This can be avoided only by 

 applying the heat on a different principle, which 

 consists in first making the fire heat certain appa- 

 ratus with considerable surface, which then, by 

 radiation and contact with the air of the apart- 

 ment, diffuses its heat throughout it. This is the 

 principle of the other methods of warming, which 

 we now proceed to describe. The consideration 

 of methods that combine the two principles, will 

 come most conveniently last 

 CM 



WARMING BY STOVES. 



A close stove is simply an inclosure of metal, 

 brick, or earthenware, which is heated by burning 

 a fire within it, and then gives out its heat to the 

 air by contact, and to surrounding objects by 

 radiation. The simplest, and, so far as mere 

 temperature is concerned, the most effective and 

 economical of all warming arrangements, is what 

 is called the Dutch stove; which is simply a 

 hollow cylinder or other form of iron standing on 

 the floor, close at top, and having bars near the 

 bottom on which the fire rests. The door by 

 which the coals are put in being kept shut, the 

 air for combustion enters below the grate ; and a 

 pipe, issuing from near the top, carries the smoke 

 into a flue in the wall. If this pipe is made long 

 enough, by giving it, if neces.sary, one or more 

 bends, the heated gases from the fire may b.e 

 made to give out nearly all their heat into the 

 metal before they enter the wall ; and thus the 

 whole heat of the combustion remains in the 

 room. 



The great objection to this form of stove is, 

 that the metal is apt to become overheated, which 

 not only gives rise to accidents, but has a hurtful 

 effect upon the air. It cannot be said to burn 

 it, in the proper sense of the word, for none of 

 its oxygen is abstracted ; but it gives it a pecu- 

 liar odour, which is both unpleasant and un- 

 wholesome. This is thought to arise in some 

 measure at least from the hot iron burning the 

 particles of dust that light on it, which particles 

 consist of organic matter, such as wool, wood, 

 &c. 



Part at least of the unwholesomeness of air so 

 heated arises from its excessive dryness ; it parches 

 and withers eveiything it touches, like the African 

 simoom. It must not, however, be supposed that 

 this is peculiar to air heated by contact with 

 metal; air suddenly heated is always unwhole- 

 somely dry. This is an important point in regard 

 to the subject of wanning, and requires considera- 

 tion. The relation of vapour to the air is fully 

 explained in METEOROLOGY, which the reader is 

 recommended to consult in connection with this 

 subject. It may be stated shortly here, that a 

 cubic foot of air, say at 32, can contain a certain 

 quantity of moisture and no more ; but if heated 

 to 80, it is capable of containing five times as 

 much, and has thus become thirsty, and drinks 

 up moisture from everything that contains any. 

 Whenever the temperature within doors is much 

 higher than without, the air is in a too thirsty 

 state, and parches the skin and lungs, unless 

 means be taken to supply the necessary moisture. 

 An evaporating pan or other contrivance is an 

 essential part of warming apparatus ; it is specially 

 necessary to attend to this during east winds, 

 which are generally too dry even at their natural 

 temperature. 



All improvements on this simple and rude form 

 of stove aim at avoiding a high heat in the 

 warming surface, and this chiefly by lining the 

 fire-box with brick, and inclosing it in several 

 casings, so as to enlarge the heated surface. A 

 general notion of these contrivances may be got 

 from the annexed cut (fig. 2), representing the kind 

 of stove called a cockle. The fire is burned in 

 a small furnace within the inner case, and the air 



