difference is that the fast
battleship is much less likely to be employed as a cruiser than the
battle-cruiser was; but I pointed out in the text that the employment
even of the battle-cruiser in cruiser functions proper was likely to be
only occasional and subsidiary.

The decision to use oil as the exclusive source of the motive power of
fast battleships, and of certain types of small cruisers of exceptional
speed, is undoubtedly a very significant one. It may be taken to point
to a time when oil only will be employed in the propulsion of warships
and coal will be discarded altogether. But that consummation can only be
reached when the internal combustion engine has been much more highly
developed for purposes of marine propulsion than it is at present. At
present oil is only employed in large warships for the purpose of
producing steam by the external combustion of the oil. But it may be
anticipated that a process of evolution, now in its initial stages in
the Diesel and other internal combustion engines, will in course of time
result in the production of an internal combustion engine capable of
propelling the largest ships at any speed that is now attainable by
existing methods. When that stage is reached oil will, for economic
reasons alone, undoubtedly hold the field for all purposes of propulsion
in warships. It is held by some that this country will then be placed at
a great disadvantage, inasmuch as it possesses a monopoly of the best
steam coal, whereas it has no monopoly of oil at all, and probably no
sufficient domestic supply of it to meet the needs of the Fleet in time
of war. But oil can be stored as easily as coal and, unlike coal, it
does not deteriorate in storage. To bring it in sufficient supplies from
abroad in time of war should be no more difficult for a Power which
commands the sea than to bring in the supplies of food and raw material
on which this country depends at all times for its very existence.
Moreover, even if we continued to depend on coal alone, that coal,
together with other supplies in large quantities, must, as I have shown
in my last chapter, be carried across the seas in a continuous stream
to our fleets in distant waters, and one of the great advantages of oil
over coal is that it can be transferred with the greatest ease to the
warships requiring it at any rendezvous on the high seas, whether in
home waters or at the uttermost ends of the globe, which may be most
conveniently si