Fire-places and Kitchen Utensils. 481 



a circular plate of metal, which closes (by means of 

 flanges and screws) the front ends of the cylinders. 



In consequence of this particular arrangement it will 

 be perfectly easy to make all the cylinders of cast iron, 

 even when these boilers are destined for steam-engines 

 of the largest dimensions. The number of sets of 

 cylindrical boilers, which in each case it will be neces- 

 sary to put up, must be determined by the size of the 

 cylinders and by the quantity of steam that will be 

 wanted. Six cylindrical boilers put up in a separate 

 mass of brick-work, in the manner above described, I 

 call one set. 



It will always be found to be very advantageous to 

 have at least three or four sets of cylindrical boilers to 

 each steam-engine, instead of having one set of larger 

 cylinders ; and this not only on account of the wear 

 and tear of small fire-places being incomparably less 

 expensive than in those which are large, but also on 

 account of the economy of fuel which will be derived 

 from that arrangement, and the great convenience that 

 will be found to result from the use of small boilers, 

 which may at any time be heated and made to boil in 

 a very few minutes ; and from the advantage of being 

 able at all times to regulate the number of sets of 

 boilers in use to the load on the engine. 



It is quite impossible to make a small fire in a large 

 fire-place without a great loss of heat ; but, by having 

 a number of small separate fire-places, an engine may 

 be made to work with a light load with almost as small 

 a proportion of fuel as when it is made to perform its 

 full work. But to return to our cylindrical boilers. 



The two lower cylinders, and those two which lie 

 immediately over them, being destined for the genera- 



