PRESIDENTIAL ADDRESS. 9 
employment of the simplest form of motion—rotation—for 
converting the energy of the working fluid into useful 
torque. The resultant motion is most suitable for direct 
power applications in general, and especially so for the 
direct driving of alternating current generators, a result 
accomplished with reciprocating engines only through the 
employment of large fly-wheel capacity, and heroic design 
of both engine and generators. Parallel working with the 
turbine becomes the simplest of operations, due to the 
entire absence of cyclical speed variations, which prove so 
troublesome and expensive in the case of the reciprocating 
engine. The speeds at which Parsons’ turbines operate 
further contribute to economy of generator construction 
by reducing the number of poles required for a given fre- 
quency. The weight of the turbine units of 1,500 K.W. 
| capacity is about one quarter that of the reciprocating 
engine units of the best design per rated horse power. 
The Parsons’ turbine is very economical in steam consump- 
tion and compares favourably with reciprocating engines 
of similar power, more especially at overloads, half, and 
three-quarter loads. 
In the 1,500 K.W. turbines a Kilowatt hour can be pro- 
duced with 20 fbs. of saturated steam at 150 Ibs. pressure 
per square inch, or with 18 ibs. of steam superheated to 
120° F. The larger sizes are still more economical. Par- 
sons’ turbines are simple in design, and are adapted for the 
use of superheated steam without any of the disadvantages 
such as attend its use in reciprocating engines ; moreover 
the steam can be expanded down to the condenser pressure, 
and the condensed steam returned as feed water to the 
boilers entirely free from oil. The advantages of turbines 
over reciprocating engines may be briefly summarized as 
follows :— 
1. The steam economy at fuel load is at least as good as 
that of reciprocating engines of similar capacity, but at 
