PRESIDENTIAL ADDRESS. 579 
cent. of the power developed when running 14°6 knots. With the ship laden 
more deeply, the average development of power on the voyage was about 
one-half the maximum developed on the measured mile, and this was dis- 
advantageous to economy in the combination. Even in these unfavourable 
conditions the Otakz realised an economy in coal consumption of 8 per cent. 
on the voyage from Liverpool to New Zealand and back as compared with 
her reciprocating-engined sister ship; this represents a saving of about 
500 tons of coal. Ordinarily the ship would leave England with sufficient 
coal on board for the outward passage, so that 250 tons less coal need be 
carried and a corresponding addition could be made to cargo and freight- 
earning. Probably as experience is gained the actual economy will prove 
greater than that realised on the maiden voyage ; but even as matters stand 
there is a substantial gain, and a prospect of the extended application of 
the steam turbine to vessels of moderate and low speed. In view of results 
already obtained, the New Zealand Shipping Company have decided to 
apply the combination system to another vessel just ordered from Messrs. 
Denny. 
In designing turbine machinery for vessels of moderate or low speed 
there must necessarily be conflicting claims. For maximum efficiency in 
steam turbines a high rate of revolution is necessary ; whereas at moderate 
or low speeds it is antagonistic to propeller efficiency to run at this high 
rate of revolution. Engineers are at present much occupied with the study 
of arrangements by means of which these conflicting claims may be har- 
monised and greater total efficiency of propulsion obtained. Having regard to 
the enormous capital invested in cargo steamers of moderate speed, and the 
importance attaching to their economic working as influencing the cost of 
oversea transport, it will be obvious that it is most desirable to find an 
arrangement in which the high speed of the rotor may be reduced by means 
of some form of gearing or its equivalent, so as to enable the screw shaft and 
its propeller to be run at a speed which will secure maximum propeller 
efficiency. Many proposals have been made, including mechanical gearing 
and hydraulic or electric apparatus for transforming the rate of motion. 
Some of these are actually undergoing experimental trials, and are said to 
have given very promising results. One of the most important trials is that 
undertaken by the Parsons Marine Steam Turbine Company, which has 
purchased a typical tramp steamer, and is carrying out on her a series of 
trials in order first to ascertain accurately what are the actual conditions 
of steam and coal consumption with the present reciprocating engines, and 
then to ascertain the corresponding facts when those engines have been 
removed and a steam turbine with its associated gearing has been fitted. It 
is interesting to note in passing that in the earliest days of screw propulsion 
with slow-running engines it was found necessary to adopt gearing in order 
to increase the rate of revolution of the propellers, whereas at present 
interest is centred in the converse operation. Furthermore, if any system 
of gearing-down proves successful it may be anticipated that its application 
will be extended to swift turbine-driven steamships, since it would enable 
good propulsive efficiency to be secured in association with rapidly running 
turbines of smaller size and less weight than have been employed hitherto. 
The Marine Steam Turbine. 
The rapid development of the marine steam turbine during the last 
seven years constitutes one of the romances of engineering, and the mag- 
nitude of the work done and the revolution initiated by Mr. Charles Parsons 
will be more justly appreciated hereafter than they can be at present. In some 
quarters there is a tendency to deal critically with details and to disregard 
broader views of the situation as it stands to-day. In May 1909 there were 
275 vessels built and under construction in which steam turbines of the 
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