8 W. H. WARREN. 
Steam Turbines.—By far the most important improve- 
ment of recent years in steam engineering is the develop- 
ment of the steam turbine, which is due largely to the 
labours of the Hon. CO. A. Parsons of Newcastle-on-Tyne. 
The chronology of the steam turbine is interesting as 
indicating the unequal and erratic progress which may be 
made in the various branches of the mechanical arts, as — 
well as the anticipation of modern by ancient inventive 
genius. The reaction turbine dates back to the time of 
Hero and his contemporary, Archimedes, 120 B.C. The 
impulse turbine type is credited to Branca in 1629. In 
1705 the reciprocating engine appeared, and in 1884 Parsons 
brought out the first turbine of the multiple-expansion 
type, combining in principle the fundamental features of 
both impulse and reaction types. In 1883 was introduced 
the original form of De Laval turbine, which was of the 
reaction type and led up to the modern De Laval impulse 
turbine introduced in 1889. The Parsons turbines in the 
ill-fated Viper developed a record speed of 37°1 knots per 
hour in 1899. , 
The tendency of modern steam turbine development has 
keen along three important lines—first, mechanical sim- 
plicity; second, steam economy; and third, speed reduction. 
The De Laval impulse turbine is at present manufactured 
in Kurope and America in sizes up to 300 horse power. In 
its present form it is restricted to a somewhat limited field 
of application in consequence of its unsuitability to fluctu- 
ating loads, and its loss of efficiency due to the governing 
by throttling. 
The compactness of the Parsons’ turbine, in the words 
of Mr. J. R. Bibbins, is largely due to the concentration of 
the working parts into a single moving element, the absence 
of means for affecting a transformation of motion, necessary 
in a steam engine of the reciprocating type, and the 
