696 POPULAR SCIENCE MONTHLY. 



STEAM TURBINES ^ND HIGH-SPEED VESSELS.* 



Bv THE Hon. CHARLES A. TAKSONS, F. R. S. 



A LL heat engines at present in use take in heat from a source 

 -^^ at a high temperature and discharge most of it at a lower 

 temperature, the disappearance of heat in the process being the 

 equivalent of the work done by the engine. In all cases at the 

 present time the source of heat is from fuel of some kind, and 

 after working the engine the residue \s, discharged in the case of 

 the steam engine either to the condenser or in the exhaust steam 

 .when non-condensing. In the gas engine it is discharged in the 

 waste gases and into the water jacket around the cylinder. 



The earliest records of heat engines are found in the Pneu- 

 matics of Hero of Alexandria, about 200 b. c. He describes a 

 reaction steam turbine, a spherical vessel mounted on axes supplied 

 with steam through one of the trunnions from a boiler beneath; 

 the steam escaping through two nozzles diametrically opposite to 

 each other and tangential to the sphere, causing the sphere to 

 rotate by the reaction or momentum of the issuing steam, and anal- 

 ogous to a Barker's water wheel. 



Thus, the first engine deriving its motive power from fuel was 

 a crude form of steam turbine, and though it could have been ap- 

 plied to useful work, and could easily have been made sufficiently 

 economical to replace manual and horse power in many instances, 

 yet it lay dormant till 1629 a. d., when Bianca suggested the same 

 principle in a different form. Bianca's stearn turbine consisted 

 simply of a steam jet fed from a boiler impinging against vanes or 

 paddles attached to the rim of a wheel which was blown round by 

 the momentum of the steam issuing from the jet. 



The piston engine is, however, of comparatively modern origin, 

 and dates from about the year 1700 a. d. Engines of this class 

 are so well known that it suffices to say that they have been prac- 

 tically the sole motive-power engines from fuel in use from 1700 

 up to 1845, and have constituted one of the most important factors 

 in the development of modern engineering enterprise. 



Air engines were introduced about the year 1845, and although 

 the larger engines of the Stirling type were very economical in fuel, 

 yet, on account of the inherent difficulty of heating largo volumes 

 of air within metal chambers or pipes — a difficulty arising from the 

 low conductibility of air and consequently the overheating and 



* Abstract of the Presidential Address to the Institution of Junior Engineers, November 

 3, 1899. 



