AM) Sl-IiKAOE CONDENSE1!. 341 



therefore a less proportion goes through the sides of the boiler, 

 and is lost through the chimney ; whereas if the heat of the 

 steam, by passing into the cold air, on its way through the 

 condenser tubes, is carried into the fire-place, one-half of the 

 coal must be saved ; and you will find by calculation that the 

 quantity of air required to burn the coal, and also to condense 

 the steam, goes exactly in proper proportion for each other, and 

 for locomotive engines with a blast will go hand-in-hand almost 

 to any extent, and the size of an engine, for its power, is a 

 mere nothing. 



" xV smoke-jack fan in the ash-pit under the fire-bars, worked 

 by the engine, would draw air down the condensing tubes, and 

 force it up through the 'fire and fire-tubes always with the 

 speed required, as the steam and the condensation would increase 

 in the same ratio. 



" As it is possible to blow so much cold air into a fire as to 

 put it out, by first heating the air it would burn all the 

 stronger, and whatever heat is taken out of the condenser into 

 the fire-place from the steam that has been made use of, half 

 this extra heat will go into the boiler again, or in other words, 

 but half the quantity of cold will be put into the fire, being the 

 i-ame in effect as saving fuel. Taking heat from the condenser 

 through the boiler sides is an additional new principle in this 

 engine. I find by blowing through tubes that the condensation 

 of a surface foot of air-tube against a surface foot of boiler fire- 

 tube is greater than the fire that passes through the boiler 

 sides, where the common chimney draught is used, by nearly 

 double; but I expect when both air and fire tubes are forced by 

 a strong current of air it \\ill be nearly equal, and the increase 

 of steam and of condensation can be increased by an increased 

 current of air, so as to cause a surface foot of fire and of air 

 sides to do perhaps five times as much ; and of course the 

 machine will be lighter in proportion. I think air sides con- 

 densation preferable to water sides, as so small a space does the 

 work, and is always convenient, and its power uniformly in- 

 creasing with its speed, by the increased quantity of air, without 

 the weight of water vessels. This kind of engine can be made 

 to suit every place and purpose, and I think such an engine of 

 VOL. IT. 2 A 



