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power have been fitted in ships. There are many types, 
such as those of Parsons, Curtis, Rateau, De Laval, 
Zoelly, and others, but it was the Parsons turbine 
which led the way. Originally the turbine was con- 
nected directly to the propeller shaft. To be economi- 
cal, however, the turbine should run fast and the 
propeller slow. To achieve this object, Sir Charles 
_ Parsons introduced helical tooth gearing, the turbine 
shaft having a small pinion which geared into a large 
wheel in the propeller shaft. Such single reduction 
“gearing was successfully tried in the s.s. Vespasian in 
190g. Since then double reduction gearing, con- 
sisting of a train of four wheels, has been largely used. 
In this arrangement the pinion in the turbine shaft 
drives a wheel on an intermediate shaft, and a pinion 
‘in the second shaft drives the wheel in the propeller 
shaft. By this means it is possible to run the turbine 
at three or four thousand revolutions per minute while 
maintaining a suitable propeller speed. One of the 
finest examples of such gearing is found in the latest 
liner of the Canadian Pacific Railway Company, the 
Empress of Canada. Completed last summer, this 
essel is the largest passenger ship running in the 
Pacific. Of 21,520 tons, she is driven by twin sets of 
Brown Curtis turbines, each set having H.P., 1st I.P., 
end I.P., and L.P. turbines, which drive the propeller 
through double reduction gearing. The main gear 
wheel on the propeller shaft alone weighs 65 tons, 
while one complete set of gearing weighs about 
200 tons. Additional interest attaches to this in- 
stallation, due to the application of the principle of the 
nodal drive devised by Dr. J. H. Smith, of Belfast, in 
order to avoid trouble due to torsional oscillations of 
the various shafts. 
But while mechanical gearing of this kind has been 
used extensively, there have unfortunately been 
serious failures which have given rise to more than a 
little doubt as to the trustworthiness of such gearing. 
The elucidation of the causes of the failures is among 
the most pressing problems facing the marine engineer. 
References to this were made in the recent presidential 
addresses of Engr. Vice-Admiral Sir George Goodwin, 
Dr. W. H. Maw, and of Prof. T. B. Abell to the Institute 
of Marine Engineers, the Institution of Civil Engineers, 
and the Liverpool Engineering Society respectively, 
and the urgent need for further research was pointed 
out. Failures occur from the wearing or the breaking 
of the teeth. In some instances where wear has taken 
lace the trouble has not been serious, and with further 
“use the condition of the gearing has improved. When 
fracture takes place the broken pieces sometimes fall 
clear of the wheels, and the damage is slight. If, 
however, the broken teeth are caught in the wheels 
distortion and crushing takes place immediately, and 
the gear wheels are rendered useless. The causes of 
failure have been variously assigned to inaccurate 
cutting of the teeth, want of alignment of the shafts, 
improper design, unsuitable or faulty material, and 
the occurrence of excessive torsional vibrations in the 
shafting and gearing. This latter subject has been dealt 
with recently in a valuable paper by Messrs. A. T. Thorne 
and J. Calderwood, read before the North-East Coast 
Institution of Engineers and Shipbuilders. 
Recent improvements in steamships, whether driven 
_ by turbines or reciprocating engines, have been largely 
No. 2788, voL. 111] 
NATURE 
471 
concerned with the stokehold. Though cylindrical 
boilers still remain the rule, water-tube boilers are 
being fitted in increasing numbers, and in such vessels 
as fast torpedo craft and cross Channel steamers the 
combination of the water-tube boiler with the geared 
turbine is likely to hold its own for a long time. The 
water-tube boiler leads to a reduction in weight, it 
can be forced at a high rate of combustion, and it is 
admirably adapted for use with oil fuel. Naval 
vessels have used water-tube boilers exclusively for 
many years, but it is only recently the mercantile 
marine have taken kindly to them. The most notable 
example of the use of water-tube boilers in a merchant 
ship is found in the White Star liner, the Majestic, the 
ex-German ship Bismarck, which it is anticipated will 
run the Mauretania very close for the blue ribbon of 
the Atlantic. The world’s greatest ship, the Majestic, 
is 912 feet long, and displaces, when fully loaded, 
64,000 tons. The turbines, originally designed for 
66,000 S.H.P., are supplied with steam from 48 water- 
tube boilers of the Yarrow-Normand type. These 
have a total heating surface of 220,000 sq. ft., or some 
40,000 sq. ft. more than the boilers of H.M.S. Hood. 
Like most of the Atlantic liners the Majestic is now 
fitted for burning oil fuel. Some 15,000,000 tons of 
ships burn oil instead of coal to-day, and provided 
supplies of oil prove sufficient, the time is not far distant 
when the coal-burning ship will be obsolete. When 
used under boilers three-quarters of a pound of oil will 
do the work of a pound of coal. Then, too, the use of 
oil-fuel leads to a great reduction in the stokehold 
staff, and from the shipowners’ point of view it has 
the advantage of making it possible to reduce the 
time of a ship in port. The Olympic, for example, can 
fill her oil-tanks in six hours; coaling used to take 
44 days. 
It is not, however, with the reciprocating engine or 
with the steam turbine that the future of marine 
engineering appears mainly to lie, but with the Diesel 
internal combustion engine. Diesel brought out his 
engine so long ago as 1893. Its success ashore has 
been remarkable. For driving ships it has had to 
serve a long probation. The Atlantic was first crossed 
by a Diesel-driven ship in 1910. Since then its pro- 
gress has been more rapid, and practically all marine 
engine builders have taken up the construction of 
Diesel engines of one form or another. The motor 
ship has undoubtedly come to stay, and the placing of 
an order by the Union Steamship Company of New 
Zealand with the Fairfield Company for a motor 
driven vessel of 20,000 tons with a speed of 18 knots 
marks an important epoch in its history. This notable 
vessel will be 600 ft. long, and will be driven by four 
sets of Sulzer two-cycle Diesel engines of an aggregate 
power of 13,000 H.P. This is twice the power of any 
motor vessel running at present. Such a step is 
evidence of the degree of trustworthiness and success 
achieved by the motor ship. 
The credit of building the first motor passenger liner 
belongs to the Elder Dempster Line, which commissioned 
the Aba for its West African trade last year, and 
has now placed the Adda on the same run. Other 
companies are following the lead thus given, and while 
in 1914 there were only 297 motor ships afloat there are 
now 1620, with an aggregate tonnage of more than one 

