502 TRANSACTIONS OF THtl AMERICAN INSTITUTE. 



eight pounds of water is vaporized by a pound of fuel, and sometimes 

 twelve pounds in stationary engines. Mr. Clark, who has given consider- 

 able attention to this subject in regard to locomotives, says that the maxi- 

 mum is fourteen pounds; but in locomotives, which vaporize as economical 

 as any, about one-third of the heat is lost. Now it has been estimated that 

 the cost of the fuel of a steamship, after being placed on board, averages 

 $15 a ton; so if this apparatus of Mr. Manton would save one-third of the 

 heat the gain would be immense, about 400 tons on a trip, which would be 

 some $12,000. It appears there is a great quantity of fuel to be saved by 

 the hot blast. This system of causing the waste heat to pass through a 

 mass of material, that will absorb it instead of being thrown out into the 

 air, seems to possess many advantages, and is worthy of a careful investi- 

 gation. 

 . The Chairman. — This plan is essentially the same as Sieman's. 



Mr. Norman Wiard. — I have no doubt but that this plan is capable 

 of economical results, but the same may be attained by increasing the fire 

 surface of the boiler, and the question is, which is the best system. 



Mr. Manton. — With my apparatus we can have the gases to pass out of 

 the chimney at a nearly uniform temperature, and under no circumstances 

 need we loose more than fifty degrees of heat. 



Mr. Benjamin Garvey. — We are sometimes apt to suppose an advantage 

 when there really is none. In this apparatus of Mr. Manton the economy 

 is efiected by power expended in another direction. In order to get heat 

 in this case, we must have a great draft, which can only be had by a 

 blower, and this involves an expenditure of power. In regard to enlarging 

 the fire surface to attain greater evaporation, I will say that it has been 

 found in recent practice that by shortening the flues of locomotive boilers 

 the vaporizing capacity has been largely increased. 



Mr. Fisher. — With regard to statement which I made from the report of 

 Mr. E. K. Clark, it appears that about one-third of the heat is lost, so that 

 we have that proportion of the horse power sent up the smoke pipe in a 

 locomotive. As to the use of blowers I may say that on locomotives the 

 natural draft is of no account, so much so that when standing they do not 

 burn one-eighth of the fuel Mr. Gurney tried several experiments in order 

 to effect a draft. He ventilated a mine with a jet of steam, but found it cost 

 much more than by using a blower. The jet expended moi-e power than 

 the mechanical appliances used to work a blower, so he abandoned it. 



Iron-clad Vessels of War. 



The subject for the regular discussion was here resumed. 



Captain R. G. Macdougal exhibited a model of his gunboat. He said: 

 The guns are arranged on a circular table, similar to that used for turning 

 locomotives, and there are nine ports arranged in different directions, and 

 the table is turned by steam. One gun is fired every fourth time. This 

 gives the gun time to cool. There are two propellers, so as to turn in a 

 narrow stream or on a small circle. Captain Macdougal here made a dia- 

 gram on the blackboard, showing the construction of the diflerent parts of 

 his gunboat, which he explained very minutely. 



