702 ANNUAL EEPOKT SMITHSONIAN INSTITUTION, 1913. 



tion in several channel steamers, and some small Australian vessels 

 have been fitted with boilers of the Babcock-Wilcox type. A con- 

 siderable departure has been made in the fitting of the large German 

 Atlantic vessel Iniperator with boilers of the Yarrow type ; and in a 

 large liner at present under construction on the Clyde, Babcock- 

 Wilcox water-tube boilers are being adopted. 



The increasing cost of fuel, and the economy obtainable by the use 

 of superheated steam, has tended to hasten development in that direc- 

 tion, and a fair number of ships, including the liner under construc- 

 tion, just referred to, are being fitted with superheaters. A saving 

 of 10 to 15 per cent in fuel consumption has been shown to be pos- 

 sible, and it is likely that superheating will be much more widely 

 adopted in the near future. 



With regard to the gain in fuel economy, brought about by the 

 developments which have taken place, it is difficult, owing to the 

 varying factors involved, to state this in general terms. Average 

 values, however, are given in the table opposite. 



The problem of mechanical stoking, which has been successfully 

 solved for the less severe conditions of land practice, still awaits solu- 

 tion as regards conditions afloat. Ideal conditions in this respect 

 would be more easily reached by the extended use of liquid fuel, the 

 advantages of which are obvious. Much progress has been made in 

 perfecting apparatus for the proper combustion of oil, and its use 

 would very rapidly be extended, but for the sufficient reason that the 

 present relative prices of oil and coal are such as to make the use of 

 oil for burning in furnaces, except in specially favorable instances, 

 out of the question commercially. On the general economic question 

 of the oil supply depends also the rate of future progress of the large 

 internal combustion engine, the latest development in marine engi- 

 neering. 



The application of the internal-combustion engine to marine pro- 

 pulsion is no new development, small engines having been constructed 

 for this purpose more than 20 years ago. During the last decade, 

 however, rapid progress has been made with small engines using the 

 lighter petroleum spirits and oils, and the extent to which the steam 

 engine has been superseded in small craft, such as launches and pin- 

 naces, is apparent. For this class of work the small weight and bulk 

 of the internal-combustion engine and its general convenience are 

 such as to make the steam engine almost obsolete. The problem of 

 producing a reliable engine of the internal-combustion type of larger 

 power, without undue complication of design, and sufficiently low 

 in first cost and maintenance to be able to compete successfully with 

 the" steam engine or geared turbine, is a much more difficult one. 

 Much experimental Avork has been done with this end in view, and 

 there are many attractive possibilities. 



