which had now been in use for nearly ten years, and although the
present voyage was not a particularly rapid one, it had been made
in a little less than three days.

As may be easily imagined, a vessel like this was a very
different craft from the old steamers which used to cross the
Atlantic--"ocean greyhounds" they were called--in the latter part
of the nineteenth century.

It would be out of place here to give a full description of the
vessels which at the period of our story, in 1947, crossed the
Atlantic at an average time of three days, but an idea of their
construction will suffice. Most of these vessels belonged to the
class of the Euterpe-Thalia, and were, in fact, compound marine
structures, the two portions being entirely distinct from each
other. The great hull of each of these vessels contained nothing
but its electric engines and its propelling machinery, with the
necessary fuel and adjuncts.

The upper portion of the compound vessel consisted of decks and
quarters for passengers and crew and holds for freight. These
were all comprised within a vast upper hull, which rested upon
the lower hull containing the motive power, the only point of
contact being an enormous ball-and-socket joint. Thus, no matter
how much the lower hull might roll and pitch and toss, the upper
hull remained level and comparatively undisturbed.

Not only were comfort to passengers and security to movable
freight gained by this arrangement of the compound vessel, but it
was now possible to build the lower hull of much less size than