RECIPROCATING AND TURBINE ENGINES ON STEAMSHIPS. 193 
result and be simpler and less expensive. ‘The chances for air leaks, where 
the reciprocating engine delivers the steam to the turbines at 30 pounds 
absolute, is reduced to one stuffing box at the condenser end of the low 
pressure turbines while, in the case of two sets of reciprocating engines 
exhausting to one turbine at 9 or 10 pounds absolute, there are always 
possible air leaks at both ends of the turbine and at the stuffing boxes of 
both low pressure cylinders of the reciprocating engines. 
In one arrangement proposed by the writer, the air pumps, both wet 
and dry, are operated from the low pressure cylinder crossheads. This might 
be objected to as not providing any means for maintaining a vacuum should 
the reciprocating engine be disabled. ‘The object in making the air pumps 
part of the main reciprocating engine is simply one of first cost and some 
advantage in economy of steam and of work in caring for the pumps. The 
writer has forestalled this objection and prefers the independent pumps as an 
additional security against any failure of the reciprocating engine. Of course 
independent air pumps can be installed, in which case they should exhaust 
into the turbine steam chests. Our sketch plan shows this arrangement. 
‘In a paper read by A. C. E. Rateau at the Jubilee Meeting of the Insti- 
tution of Naval Architects, July 5 of this year, which has just reached the 
writer this morning, July 20, there seems to be something that would 
indicate that the arrangement proposed in this paper had been considered 
by Professor Rateau. He says that, “In 1906 we fitted the French 
Destroyer Voltigeur with an improved arrangement of engines. The power 
is distributed on three shafts (center shaft reciprocating engine with turbines 
on wing shafts). Up to a speed of 20 knots, the reciprocating engine ex- 
hausts intothe turbines but above that speed the engines becomeindependent. 
We could therefore have realized a perfect engine up to a speed of 20 knots 
if the reciprocating engine and the turbines had been designed solely with 
the view of obtaining better results by working by stages, but instead of this, 
they were designed more particularly with the object of obtaining the 
maximum efficiency at full power.’”’ In other words, the Professor, by 
providing a third condenser for the reciprocating engine to exhaust into at 
full power, added to the power developed at the expense of the lost economy 
in the low pressure end of the reciprocating engine and in the high pressure 
end of the turbine and, even when exhausting from his reciprocating engine 
into the turbines, he lost in economy by using low pressure steam in turbines 
designed to be operated by steam direct from the boilers. 
In utilizing the expansion in reciprocating engines down to a pressure 
of say 9 pounds absolute, we must have cylinders of large dimensions sub- 
ject to marked changes in temperature every revolution, involving large 
losses due to condensation combined with large frictional losses causing a 
