THE STEAM TURBINE—PARSONS. 109 
The statistics of the turbine vessels Onward and Invicta, on the 
Boulogne and Folkestone route, have confirmed these results. 
The trials of the third-class cruiser Amethyst, in 1904, and of her 
sister vessel the Topaz, propelled by triple expansion engines and 
screws, showed that, at a speed of 11 knots, the consumption of steam 
was the same in both vessels, but, as the speeds were increased, the 
turbine vessel gained relatively in economy, and at 18 knots was 15 
per cent more economical, and at 204 knots 31 per cent, and at full 
speed 36 per cent. Her superior economy in coal enabled her to reach 
a speed of 23.63 knots, or 1} knots more than the Z’opaz, on the same 
coal allowance. The results of the trials also showed that, at a 
speed of 20 knots, the Amethyst could steam about 50 per cent more 
miles than the Zopaz on the same quantity of coal. 
The experience as regards Atlantic liners is as yet limited to three 
vessels, the Virginian, the Victorian, and the Carmania. 'The first 
two are of the Allan line, 520 feet in length, 15,000 tons displacement, 
and 12,000 horsepower, with a sea speed of from 16 to 17 knots. 
These vessels have been running since the spring of 1905, and 
the consumption of coal has been estimated to be no more, and prob- 
ably less, than would have been the case had they been fitted with 
the most economical engines of ordinary type. 
The Cunard liner Carmania, of 672 feet in length, 30,000 tons dis- 
placement, and 21,000 horsepower, is a sister vessel to the Caronia, 
propelled by quadruple expansion engines of the most economical 
type, and during the last four months the consumption of coal in the 
two vessels has been carefully measured, but it is too soon as yet to 
give the results. However, on the official trials, the turbine vessel 
exceeded the speed of her sister ship by 1 knot. 
Some of the advantages found to exist with turbine propulsion 
are, that the propellers never race in the heaviest seas, and that, as a 
consequence, the speed is better maintained under all weather condi- 
tions; and the cause of this is to be traced to the smaller diameter of 
the propellers, wider blades, and deeper immersion. There is also 
much less vibration. 
The tendency of late has been to increase the reversing, or astern, 
power of turbine vessels to such an extent that, in many cases, the 
stopping and maneuvering powers have been equal to those of twin 
screw vessels with reciprocating engines. The starting of turbine 
vessels is relatively quick, for the torsional force of a turbine, when 
starting from rest with full steam on, is at least 50 per cent greater 
than the torque at the usual running speed, because the blades, when 
running slowly, meet the full blast of the steam instead of moving 
with it as they do at their usual speeds. With ordinary engines the 
starting torque does not exceed the torque at full speed. When 
