410 THE APPLICATIONS OF PHYSICAL FORCES. [BOOK iv. 



The production of steam is, so to speak, immediate, for a boiler 

 of this system with a volume of less than 4 cubic metres (3*74), 

 and with 10 square metres of heating surface, can turn 200 kilo- 

 grammes of water into steam in one hour. 



There are, besides this, other systems of circulating boilers in 

 England, such as Scott's, and in France, Larmanegat's and' Bouteguy's. 

 We can only name them, and pass on to recapitulate in a few lines, 

 General Morin's opinion on the respective advantages of the ordinary 

 boilers compared with these new systems. 



The first have long use for their sanction. They produce the steam 

 required without much care or attention, and with great regularity ; 



FIG. 287. Circulating boiler. Belleville's system. 



their ordinary working is simple and convenient ; but they take up a 

 great space, and are perhaps more liable to explosions. On the 

 contrary, circulating boilers, while less cumbersome and costly,* and, 

 so to speak, .inexplosible, have the advantage of a rapid generation 

 of steam, but they require more attention, and are not more econo- 

 mical of the fuel. They appear to be specially applicable to engines 

 in small factories. 



