ALQUIST GEARING FOR SHIP PROPULSION. 193 
ters seem to have been ignored in statements which have recently been made on the subject. 
Cruising Economy.—With the electric design, the number of motors and turbines used 
can be adapted to the demand for power, while with the other all parts must be kept running. 
This gives very important gain in economy at all speeds below the maximum. At 19 knots 
only one turbine is required to drive the ship, and electrical arrangements are made by which 
it can be run at full speed instead of running at half speed, as it would if the ratio were fixed 
as by gearing. Thus the steam efficiency at 19 knots, a desirable cruising speed, is equal to 
the best attainable at any speed. Assertions which have been made by shipbuilders and others 
that equal cruising results can be obtained by the use of cruising turbines are obviously ab- 
surd. The cruising turbines themselves would be greatly inferior to the single main tur- 
bine so used, and they would be burdened with all the drags which are mentioned above. 
Cruising economy gives increased cruising radius without renewal of fuel supply. This has 
always been considered a matter of the greatest importance in warships; it is a feature in 
respect to which electric drive can have no rival. 
State of Development and Expediency.—Enough has been said to give an idea of the 
reasons for the use of electricity in such ships, but in addition it should be considered that 
everything used in such an electric installation is a matter of exact knowledge and wide 
experience, while methods of gearing on such a scale are backed by little and brief experi- 
ence and are the subject of wide difference of opinion as to methods of design and propor- 
tions. 
The writer believes that the differences of weight and cost which have been predicted 
by shipbuilders and others are not based upon just comparisons, but that even if they are 
true they are not sufficient to balance the practical merits of electric drive for such vessels. 
For these reasons it is believed that when prejudices are overcome, electricity will de- 
velop an extensive use in large high-power warships. In such light vessels as scouts and 
destroyers, for reasons of weight and space, it is relatively much less desirable, but even in 
such cases with the lightest and most compact designs and with very high pressure and 
superheat, it might in the future develop a legitimate application. In merchant ships also it 
may afford great advantages. With electricity, turbine units can be installed in duplicate, 
either in single or twin screw ships. Machinery can be installed where convenient with 
motors near propellers and turbines near boilers; auxiliaries can be driven electrically from 
the main units. The highest superheat can be used without danger or complication, and 
main units can be applied to other power uses such as cargo pumping or handling. These 
advantages have led to the preference of electric drive at a higher price in certain large 
freighters recently ordered, and will doubtless lead to many other applications in ships of 
various types. 
The advantages here mentioned have been developed with a wonderful skill and fore- 
sight by the Swedish engineer Ljungstrom in the 900 horse-power ship Mjolner which has 
been in successful operation for about two years. This vessel has shown a fuel economy de- 
cidedly superior to anything produced elsewhere in a steamship, and has maintained this 
high standard throughout her period of service. Such a result with such small power is 
very remarkable and significant. The Mjolner uses an extremely high degree of superheat. 
In reply to Mr. MacAlpine’s discussion of my paper I can only repeat that the appa- 
ratus works and that its performances show no indication of difficulties through the defi- 
ciencies which he mentions. In large vessels in which these gears are operated the sound is 
hardly noticeable even in the engine-room and the surfaces of the teeth have acquired a 
