SEPTEMBER 28, 1899] 
NATURE 
529 
of what it was in 1840. Ships have been more than trebled in 
length, about doubled in breadth, and increased tenfold in dis- 
placement, The number of pissengers carried by a steamship has 
been increased from about 100 to nearly 2000. The engine-power 
has been made forty times as great. , The ratio of horse-power 
to the weight driven has been increased fourfold. The rate of 
coal consumption (measured per horse-power per hour) is now 
only about one-third what it was in 1840. To drive 2000 tons 
weight across the Atlantic at a speed of 84 knots, about 550 
tons of coal were then burnt : now, to drive 20,000 tons. across 
at 22 knots, about 3000 tons of coal are burnt. With the low 
pressure of steam and heavy slow-moving paddle-engines of 
1840, each ton weight of machinery, boilers, &c., produced only 
about 2 horse-power for continuous working at sea. With 
modern twin-screw engines and high steam pressure, each ton 
weight of propelling apparatus produces from 6 to 7 horse- 
power. Had the old rate of coal consumption continued, 
instead of 3000 tons of coal, go0o tons would have been required 
fora voyage at 22 knots. Had the engines been proportionately as 
heavy as those in use sixty years ago, they would have weighed 
about 14,000 tons. In other words, machinery, boilers, and 
coals would have exceeded in weight the total weight of the 
Campania as she floats to-day. There could not be a more 
striking illustration than this of the close relation between im- 
provements in marine engineering and the development of 
steam navigation at high speeds. 
Equally true is it that this development could not have been 
accomplished but for the use of improved materials and 
Structural arrangements. Wood, as the principal material for 
the hulls of high-powered swift steamers, imposed limits upon 
dimensions, proportions and powers which would have been a 
bar to progress. The use of iron, and later of steel, removed 
those limits. The percentage of the total displacement devoted 
to hull in a modern Atlantic liner of the largest size is not much 
greater than was the corresponding percentage in the wood- 
built 4rz/annia of 1840, of one-third the length and one-tenth 
the total weight. 
Nor must it be overlooked that with increase in dimensions 
have come considerable improvements in form, favouring 
economy in propulsion. This is distinct from the economy 
tesulting from increase in séze, which Brunel appreciated 
thoroughly half a century ago when he designed the Great 
Sritotx and. the Great Eastern. The importance of a due 
celation’ between the lengths of the ‘‘entrance and run” of 
steamships and their intended maximum speeds, and the 
advantages of greater length and fineness of form as speeds are 
increased, were strongly insisted upon by Scott Russell and 
Froude. Naval architects, as a matter of course, now act upon 
the principle, so far as other conditions permit. For it must 
never be forgotten that economy of propulsion is only one of 
many desiderata which must be kept in view in steamship 
design. Structural weight and strength, seaworthiness and 
stability, all claim attention, and may necessitate modifications 
tn dimensions and form which do not favour the maximum 
economy of propulsion. 
Swift Passenger Steamers for Long Voyages. 
Changes similar to those described for the Transatlantic 
service have been in progress on all the great lines of ocean 
traffic. In many instances increase in size has been due, not 
only to increase in speed, but to enlarged carrying power and 
the extension of the lengths of voyages. No distance is now 
found too great for the successful working of steamships, and 
the sailing Heet is rapidly diminishing in importance. So far 
as long-distance steaming is concerned, the most potent factor 
has undoubtedly been the marvellous economy of fuel that has 
resulted from higher steam pressures and greater expansion. In 
all cases, however, advances have been made possible, not 
merely by economy of fuel, but by improvements in form, 
structure and propelling apparatus, and by increased dimen 
sions. 
Did time permit, this might be illustrated by many interesting 
facts drawn from the records of the great steamship companies 
which perform the services to the Far East, Australia, South 
America, and the Pacific. As this is not possible, I must: be 
content with a brief statement regarding the development of 
the fleet of the Peninsular and Oriental Company. 
_ The paddle steamer William Fawcett of 1829 was about 75 
feet long, 200 tons displacement, of 60 nominal horse-power 
{probably about 120 indicated. horse-power), and in favourable 
NO. 1561, VOL. 60] 
weather steamed at a speed of 8 knots. Her hul was of wood, 
and, like all the steamers of that date, she had considerable 
sail-power. 
In 1853 the Azmalaya iron-built screw steamer of this line was 
described as ‘‘ of larger dimensions than any then afloat, and 
of extraordinary speed.” She was about 340 feet long, over 
4000 tons load displacement, 2000 indicated horse-power on 
trial, with an average sea-speed of about 12 knots. The steam 
pressure was 14 lbs. per square inch, and the daily coal con- 
sumption about 70 tons. This vessel was transferred to the 
Royal Navy and did good service as a troopship for forty years. 
In 1893 another Hza/aya was added to the company’s fleet: 
She was steel-built, nearly 470 feet long and 12,000 tons load 
displacement, with over 8000 indicated horse-power and a 
capability to sustain 17 to 18 knots at sea, ona daily consump- 
tion of about 140 tons of coal. The steam pressure is 160 lhs. 
per square inch, and the engines are of the triple expansion type. 
Comparing the two Azmaya/as, it will be seen that in forty 
years the length has been increased about qo per cent., dis- 
placement trebled, horse-power quadrupled and speed increased 
about 50 per cent. The proportion of horse-power to displace- 
ment has only been increased as three to four, enlarged 
dimensions having secured relative economy in propulsion. 
The rate of coal consumption has been probably reduced to 
about one-third of that in the earlier ship 
The latest steamers of the line are of still larger dimensions, 
being 500 feet long and of proportionately greater displace- 
ment. [It is stated that the Azma/aya of 1853 cost 132,000/. 
complete for sea; the corresponding outlay on her successors is 
not published, but it is probably twice as great. 
On the service to the Cape similar developments have taken 
place. Forty years ago vessels less than 200 feet long and 
about 7 knots performed the service, whereas the latest additions 
to the fleets exceed 500 feet in length, and can, if required, be 
driven at 17 to 18 knots, ranking in size and power next’ to the 
great Transantlantic liners. ) 
Commercial considerations necessarily regulate what is under- 
taken in the construction of merchant steamers, including the 
swilt vessels employed in the conveyance of passengers and 
mails. The investment of 600,000/. to 700,000/. in a single 
vessel like a great Transatlantic liner is obviously a serious 
matter for private owners; and even the investment of half 
that amount in a steamer of less dimensions and speed is not to 
be lightly undertaken. It is a significant fact that, whereas 
fifteen years ago nearly all the largest and swiftest ocean 
steamers were British built and owned, at the present time there 
is serious competition in this class by German, American 
and French companies. It is alleged that this change has 
resulted from the relatively large subsidies paid by foreign 
Governments to the owners of swift steamers ; and that British 
owners, being handicapped in this way, cannot continue the 
competition in size and speed on equal terms unless similarly 
assisted. This is not the place to enter into any discussion of 
such matters, but they obviously involve greater considerations 
than the profit of shipowners, and have a bearing onthe naval 
defence of the Empire. In 1887 the Government recognised 
this fact, and made arrangements for the subventiun and 
armament of a number of the best mercantile steamships’ for 
use as auxiliary cruisers. Since then other nations have adopted 
the policy, and given such encouragement to their shipowners 
that the numbers of swift steamers suitable for employnient as’ 
cruisers have been largely increased. Not long since’the First 
Lord of the Admiralty announced to Parliament that the whéle’ 
subject was again under consideration. : 
Cargo and Passenger Steamers. ~ ' 
Cargo steamers, no less than passenger steamers, have been 
affected by, the improvements mentioned. Remarkable 
developments have occurred recently, not merely inthe purely 
cargo-carrier, but in the construction of vessels of large size’ 
and good speed carrying very great weights of cargo and 
considerable numbers of passengers. The much-decried 
“‘ocean-tramp” of the present day exceeds in speed the 
passenger and mail steamer of fifty years ago. Within ten 
years vessels in which cargo-carrying is the chief element of 
commercial success have been increased in length from 300 or 
400 feet to 500 or 600 feet ; in gross register tonnage from 5000 
to over 13,000 tons ; and in speed from 10 or 12 knots'to 15 or 
16 knots. Vessels are now building for the Atlantic service 
which can carry 12,000 to 13,000 tons deadweight, in addition 
