= 
‘ 
Or 
1903.) EMMET—THE CURTIS STEAM TURBINE. 
surface condensers under such conditions renders unnecessary the 
introduction of air either in feed or circulating water, and conse- 
quently makes possible a very high vacuum with small air-pumping 
apparatus. 
The results shown by these curves are obtained from a machine 
of 600 Kw. capacity, and are naturally inferior to results which are 
expected from the very large units which are now being built. It 
is hoped that very soon after the reading of this paper a 5000 Kw. 
unit, which is now complete, will be put into operation in Chicago. 
This machine is expected to give considerably better steam econo- 
mies than are shown by the accompanying curves, and will be supe- 
rior particularly in the matter of light-load performance. The 
variation of efficiency in this machine from half load to fifty per 
cent. overload will not exceed three per cent. 
The external appearance and dimensions of this 5000 Kw. unit 
are shown by one of the drawings which accompany this paper, 
and another drawing shows this unit compared with an engine- 
driven generating unit of similar capacity. Each unit is shown as 
complete with prime mover and generator, one being the machine 
for Chicago, above mentioned ; the other, one of the units which 
are operating in the Manhattan Railway Company’s Power Sta- 
tion at New York. The comparison sufficiently illustrates the 
improvement which the turbine has introduced. The respective 
weights of these completed units, exclusive of foundation, are in 
the ratio of 1: 8, and the saving in foundations alone is a very 
important item. Other drawings which accompany this paper 
show a 500 Kw. unit recently installed at Newport, and also a com- 
parison drawn to the same scale between this 500 Kw. unit and a 
cross compound engine unit of equal capacity designed to operate 
at 1oo R.P.M. The contrast here is even more striking. 
If the extreme simplicity of the Curtis turbine is considered in 
combination with these figures and comparisons, it is easy to appre- 
ciate that a very great engineering advance has been accomplished. 
It has been conservatively estimated that engine units, like those 
in the Manhattan Company’s station, can be replaced by turbines 
like that in Chicago, and that the cost of such replacement can 
be paid for by saving in operating expenses in three years. 
Whenever an improvement has been effected in prime movers, 
the influence upon engineering and business conditions has been 
very marked. When the release cut-off principle was introduced 
