of wood--the boards used being
exceedingly thin, but the injection of some substance which did not
add materially to the weight while it gave leather-like toughness,
provided the necessary combination of lightness and strength. When
metal was used it was generally an alloy--two white-coloured metals
and one red one entering into its composition. The resultant was
white-coloured, like aluminium, and even lighter in weight. Over the
rough framework of the air-boat was extended a large sheet of this
metal which was then beaten into shape and electrically welded where
necessary. But whether built of metal or wood their outside surface
was apparently seamless and perfectly smooth, and they shone in the
dark as if coated with luminous paint.

In shape they were boat-like, but they were invariably decked over,
for when at full speed it could not have been convenient, even if
safe, for any on board to remain on the upper deck. Their propelling
and steering gear could be brought into use at either end.

But the all-interesting question is that relating to the power by
which they were propelled. In the earlier times it seems to have been
personal vril that supplied the motive power--whether used in
conjunction with any mechanical contrivance matters not much--but in
the later days this was replaced by a force which, though generated in
what is to us an unknown manner, operated nevertheless through
definite mechanical arrangements. This force, though not yet
discovered by science, more nearly approached that which Keely in
America is learning to handle than the electric power used by Maxim.
It was in fact of an etheric nature, but though we are no nearer to
the solution of the problem, its method of operation can be described.
The mechanical arrangements no doubt differed somewhat in different
vessels. The following description is taken from an air-boat in which
on one occasion three ambassadors from the king who ruled over the
northern part of Poseidonis made the journey to the court of the
southern kingdom. A strong heavy metal chest which lay in the centre
of the boat was the generator. Thence the force flowed through two
large flexible tubes to either end of the vessel, as well as through
eight subsidiary tubes fixed fore and aft to the bulwarks. These had
double openings pointing vertically both up and down. When the journey
was about to begin the valves of the eight bulwark tubes which pointed
downwards were opened--all th