196 THE PARSONS MARINE STEAM TURBINE AND ITS 
Three small cruisers of the three-shaft type are at present under con- 
struction for the Chinese Navy. In these installations no separate cruising 
turbines are being fitted, but the high pressure turbine has been arranged with 
an additional stage to improve the economy at cruising speeds and at full 
power, bye-pass valve arrangements will be made use of admitting steam to 
the second stage. (See Plate 99.) 
Among the smaller cruisers and scout cruisers, the four-shaft arrange- 
ment has been adopted largely. 
In England there are 14 vessels of this type at sea, some of which have 
cruising turbines in parallel, but in the latest design the machinery arrange- 
ment is similar to battleship and cruiser practice. Two are under construc- 
tion for the Australian Colonies. The first German turbine cruiser Lubeck 
had such an arrangement and three others have since been completed for 
the same Navy. 
A similar design was adopted in U. S. S. Chester, the first Parsons 
turbine warship in the United States Navy. (Plate 97.) 
In the case of the large experimental turbine destroyer H. M. S. Swift 
the machinery was arranged on four shafts with the turbines in two engine 
rooms and on trial this vessel made an average speed of about 35.25 knots. 
Dealing with battleships and cruisers of the Dreadnought type, four 
shafts are fitted, which are driven by two independent sets of ahead turbines 
consisting of two high pressure on outboard shafts and two low pressure on 
inboard shafts. [wo cruising turbines are arranged in parallel at forward 
end of each low pressure turbine. All shafts are arranged with astern tur- 
bines, which are in two sets. Each set consists of a high pressure and low 
pressure turbine respectively. (Plate 98.) 
In the latest ships of this type, cruising turbines have been dispensed 
with, and although it was recognized that the addition of cruising turbines 
improved the economy to a large extent, the complication together with the 
fact that such turbines are often running idly, decided against installing them 
in ships of this type, especially where cruising turbines are fitted in parallel. 
The saving in weight, by omitting cruising turbines, was not made use of 
in cutting down the machinery weights, but the main turbines were increased 
in size so as to improve their efficiency, and at the forward end of each high 
pressure ahead, an additional expansion was fitted which is used when cruis- 
ing, and for full power conditions bye-pass valve arrangements are made 
use of. (Plate 99.) 
Five vessels of this type have completed all trials most successfully, 
four of which are battleships and one a battleship cruiser. Twelve additional 
ships of a similartype are now under construction in England, having speeds 
