uired of the
mail steamer. The Havre mail steamers, the "Arago" and "Fulton," never
carry less than six engineers each, although they could be run across
the ocean with three under a hard working system. But this number
insures the greater safety of the ship under ordinary circumstances,
and is absolutely necessary in any case of accident and danger. It is
the same case with the firemen. When, in a heavy storm, the fire
department may be imperfectly manned, the ship has taken one of the
first chances for rendering the engines inefficient, and being finally
lost. And all of these extra and indispensable _employees_ make an
extra drain on the income of the ship, and add to the extreme
costliness of a high adequate mail speed.

5. It is clear, then, that an adequate mail speed requires more fuel,
more engineers, more firemen, more coal-stokers, and more general
expense. The question of fuel is, however, alone the most important of
all those affecting the attainment of high speed, and the item whose
economy has been most desired and sought, both by those attempting to
carry freight, and those who carry the mails and passengers. The
principal points of interests concerning it are, the enormous quantity
which both theory and practice show to be necessary to fast vessels;
the large sum to be paid for it, and the steadily increasing price;
and the paying freight room which its necessary carriage occupies. In
fast steaming, the supply of coal to the furnaces frequently arrives
at a point where many additional tons may be burned and yet produce no
useful effect or increase of power. The draft through the furnaces and
smoke stacks is so rapid and strong as to take off a vast volume of
heat; and this, coupled with a large quantity of heat radiated from
the various highly heated parts and surfaces, requires a consumption
of fuel truly astonishing. If we reflect that at the twelve principal
ports of Great Britain in the year of 1855, the tonnage entered was
6,372,301, and departed 6,426,566, equal to 12,798,867 total, and this
during the war, that a large part of this was steam tonnage, and that
the total imports and exports of Great Britain for 1856 were
1,600,000,000 dollars, we can somewhat appreciate the present and
future uses of coal, and its inevitably large increase in price. The
two hundred and seventy steamers in the British Navy, with about
50,000 aggregate horse power, consumed in 1856, according to a report
made to a Co