Fire-places and Kitchen Utensils. . 195 



When large boilers are shallow, and when their bottoms 

 are supported on the tops of narrow flues, the pressure 

 or weight of their contents being supported by the walls 

 of the flues, the metal of which the boiler is constructed 

 may be very thin, which will not only diminish very much 

 the first cost of the boiler, but will also greatly contribute 

 to its durability ; for the thinner the bottom of a boiler 

 is, the less it is fatigued and injured by the action of the 

 fire, and the longer, of course, it will last ; which is a 

 curious fact, that has hitherto been too little known, or 

 not enough attended to, in the construction of large 

 boilers. 



$tkly, All boilers, great and small, should be furnished 

 with covers, which covers should be constructed in such 

 a manner and of such materials as to render them well 

 adapted for confining heat. Those who have never 

 examined the matter with attention would be astonished 

 on making the experiment to find how much heat is 

 carried off by the cold air of the atmosphere from the 

 surface of hot liquids, when they are exposed naked to 

 it, in boilers without covers. But in culinary processes 

 it is not merely the loss of heat which is to be considered : 

 a great proportion of the finer and more rich and savoury 

 particles of the food are also carried off at the same time, 

 and lost, which renders it an object of serious importance 

 to apply an effectual remedy to this evil. 



As heat makes its way through wood with great 

 difficulty, and very slowly, there would perhaps be no 

 substance better adapted for constructing covers for 

 boilers than it, were it not for the perpetual changes 

 in its form and dimensions which are occasioned by 

 alternate changes of dry ness and moisture ; but these 

 alterations are so considerable, and their effects so 



