110 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1907. 
maneuvering, turbines can not fail to respond when steam is turned 
on, for they have no dead centers upon which to stick, as in the 
reciprocating engine. 
From the fact that the faster and larger the vessel the better has 
been the performance, it seems safe to infer that the two very large 
and fast Cunarders now building will give satisfactory results, and 
the same may be expected as regards new turbine construction in 
ships of war. 
The diagram (pl. vit) shows the various steps in the development 
of the steam turbine as applied to marine propulsion. 
The total horsepower in steamships sailing under all flags is at 
present about 8,000,000. Of this total, about one quarter, or 2,000,000, 
is in the faster class of ships to which turbines are suitable. 
Of the remaining 6,000,000 horsepower, about three to four are 
in the larger class of ocean tramps, and the remainder in coasting 
steamers and small river boats, ete. 
By a combination of the turbine with the reciprocating engine 
there seems to be no doubt that the three or four millions horsepower 
of large ocean tramps may be successfully propelled with a saving 
of from 15 to 20 per cent in cost of fuel. 
This combination has not yet been applied to any vessel. In it 
the reciprocating engine first expands the steam from the boiler down 
to about atmospheric pressure, and then passes on to the turbines, 
which complete the expansion down to the condenser pressure. The 
turbine thus utilizes the lower part of the expansion, which the re- 
ciprocating engine can not do, and the combination is therefore a 
good one. For maneuvering or stopping the vessel, either the engine 
or the turbines, or both, may be used, and there seems to be no doubt 
that this arrangement will come into vogue for the slower class of 
vessels of larger size. 
Turbines have been applied to other uses within the last ten years. 
The most important of these are for the working of rotary blowers, 
air compressors, and water pumps. 
The photograph (pl. vit) shows a cross section through a turbo- 
blowing engine, capable of compressing 21,000 cubic feet of free air 
per minute to a pressure of 17 pounds per square inch, which repre- 
sents about 1,000 horsepower in the air, reckoned in adiabatic com-_ 
pression. In general construction the turbine air-blower portion is 
similar to a steam turbine. The blades or vanes which propel the air 
are plano-convex in section, and set in rows at an angle similar to 
that of the blades of a ship’s propeller. Between the rows of moving 
blades are rows of guide blades inwardly projecting from the case. 
These latter are also of plano-convex section, and are set with their 
