116 
MARVIN. 
in the improvement and development of steam-engines of the 
reciprocating piston type. The modern multiple expan¬ 
sion engines, so widely used on all ocean-going and similar 
large vessels, and the forms so familiarly known in all cen¬ 
tral power stations and plants for the development and dis¬ 
tribution of great quantities of electrical and mechanical 
energy, embody today all that is best of a growth of nearly 
two hundred and fifty years. Although a very high state of 
perfection has thus been attained, the steam-engine, at best, 
is but an imperfect affair for the transformation of energy, and 
further marked improvement of the best modern cylinder 
engines seems now scarcety possible. Under these circum¬ 
stances it is interesting to notice that the foremost thinkers 
among mechanical engineers of late years have turned their 
attention to the oldest types of steam-engines of which his¬ 
tory gives us any record—that is, the eolipile or re-action en¬ 
gine of Hero and the steam turbine invented by Branca in 
the 15th century. These ancient types proved nearly worth¬ 
less in the hands of the original inventors, owing to their 
ignorance and disregard of the thermodynamic laws in¬ 
volved in their design and construction. Today, however, 
engineers find that steam turbines, when properly designed, 
equal or even surpass in efficiency the very best engines of 
the old type. 
The construction of turbines is characterized by simplicity 
itself. Valves, cylinder lubrication, reciprocating parts, and 
the multitude of accessories essential to the ordinary engine 
of high efficiency are all conspicuously absent. It is found 
the thermodynamic action of the steam can be made to take 
place with almost ideal efficiency, and it appears the prin¬ 
cipal disadvantage presented is the excessively high speeds 
of rotation involved, ranging from 10,000 to 20,000 or more 
revolutions of the main turbine shaft per minute. 
This type of prime mover bids fair to very largely rev¬ 
olutionize matters in the power equipment of naval and other 
vessels where great power, speed, and the maximum efficiency , 
coupled with minimum weight and bulk, are all-important 
desiderata. 
February 7, 1901. 
