520 



NATURE 



[September 30, 1897 



THE PROGRESS OF THE STEAM TURBINE. 



THE earliest notices of heat engines are found in the 

 "Pneumatics" of Hero of Alexandria, which dates 

 from the year 200 P.c. One of the steam or motive 

 power engines there mentioned is the yEolipiles, a steam 

 reaction engine consisting of a spherical boiler pivoted 

 on a central axis beneath which is placed a flame. The 

 steam escapes by bent pipes facing tangentially in 

 opposite directions at opposite ends of a diameter 

 perpendicular to the axis. 



economy the turbine was made what is called compound, 

 or, in other words, a series of successive turbine wheels 

 were set one after the other on the same spindle, so that 

 the steam passing through them one after the other, the 

 fall in pressure being spread over the series of turbines 

 should be gradual, and the velocity of the steam nowhere 

 more than was desirable for obtaining a high efficiency 

 for each turbine of the series. 



The turbine motor consists of a cylindrical case with 

 rings of inwardly projecting guide blades, within which 

 revolves a concentric shaft with rings of outwardly pro- 



-Sectional view of a Compound Turbine, showing the turbine blades and also the steam admission valve and beatings, as 

 well as the governor gear. 



The globe revolves by reaction of the escaping steam, 

 just as a Barker mill is driven by escaping water. 



No practical or useful steam engine appears to have 

 been made on this or any analogous principle till the 

 year 1884, though many attempts seem to have been 

 made on more or less crude lines ; meantime the piston 

 engine of Papin, Savery, Newcomen, and Watts has been 

 developed during the last 200 years, and by its general 

 use has revolutionised the means of transit and tended 

 to vastly increase the productive power of labour 

 generally. 



The want of a fast running engine for driving dynamos 

 presented an immediate field for the application and 

 development of a suitable steam turbine engine. The 

 advantages of a steady running engine having no re- 

 ciprocating parts, of small size and extreme lightness, 

 were sufficiently obvious provided that fairly economical 

 results as to steam consumption could be realised. 



The highly economical results obtained from water 

 turbines gave hopes that, provided suitable conditions 

 could be arranged, similar efficiency would be obtained 

 with steam as with water ; and assuming this to be 

 possible it would naturally follow, after taking all other 

 losses into account, that the steam turbine would be more 

 economical in steam than the piston engine. 



These possibilities, and the interest of applying a 

 practically new method for motive-power purposes, led 

 the Hon. C. A. Parsons to build an experimental engine 

 of ten-horse power coupled directly to a dynamo. 



For practical reasons it was, however, necessary to 

 keep the speed of rotation of the turbine as low as 

 possible, and also to construct the dynamo to run as fast 

 as possible, so as to couple the turbine directly to it ; and 

 in order to obtain the necessary conditions for steam 

 NO. 1457, VOL. 56] 



jecting blades. The rings of blades on the cylinder 

 nearly touch the shaft, and the rings of blades on the 

 shaft lie between those on the case, and nearly touch the 

 case. It will be seen, on referring to Fig. i, that there 

 is left between the shaft and the case an annular space, 

 which is filled with alternate rings of fixed and moving 



Fig. 2. — Section through bjades in annular space between shaft and casing 

 showing relative positions of fixed guide blades and moving blades. 

 The three arrows at the top indicate the direction of motion of the 

 entering steam. 



blades. Fig. 2 shows one form of blades which is used. 

 Steam entering at J (Fig. i) passes first through a rmg of 

 fixed guide blades, by which it is projected in a rotational 

 direction upon the succeeding ring of moving blades, 

 imparting to them a rotational force ; it is then thrown 

 back upon the succeeding ring of guide blades, and the 



