STEAM TURBINES AND HIGH-SPEED VESSELS. 699 



The form of the turbine was that of a rotating drum, with out- 

 wardly projecting rings of blades which nearly touched the contain- 

 ing cylindrical case, and on the case inwardly projecting rings of 

 guide blades which nearly touched the drum. In the first exam- 

 ples of the engine there were two groups of turbines right- and 

 left-handed on each side of the steam inlet, the exhaust taking 

 place at each end of the turbine case, so as to completely balance 

 end pressure from the steam. More recently one series of tur- 

 bines only has been used, those on the other side of the steam inlet 

 being replaced by packing rings or rotating balance pistons which 



•2 SHOWS THE Arraxcement nv Moving Blades and Guide Vanes in a Farsons's 

 Turbine. The top outer cover has been removed. The cylinder containing the revolving 

 barrel has, as will be seen, a greater internal diameter than the diameter of the drum. 

 It is the annular space thus formed through which the steam flows and which contains 

 the revolving blades and the fl.xed guide blades. Between each two rings of moving 

 blades there is a ring of guide blades, the latter being keyed into the containing case. 

 The vanes are set at an angle, so that the steam acts on them as wind on the sails of a 

 windmill. 



balance the end pressure and divert the whole of the steam through 

 the turbines on the other side. 



The steam entering the annular space between the shaft and 

 the case passes firstly through a ring of guide blades attached to 

 the case, and is given a rotational direction of flow; it then passes 

 to the succeeding ring of blades attached to the shaft, by which its 

 direction of rotation is reversed, thereby impressing the difference 

 of its rotational momentum in torque to the shaft. The steam 

 then passes to the second ring of guide blades, and the process is 

 repeated, and so on, gradually expanding by small increments at 

 each ring of blades; the succeeding rings of blades get longer and 

 wider, and at intervals the, diameter of the turbine drums, cylin- 

 ders, and rings are also increased. In condensing turbine engines 



