-five feet in diameter. From these
globes the air is to be exhausted, so that each of them, being lighter
than air, will support the weight of two or three men. The ship being
thus floated can be propelled by oars and sails.

Any modern reader, without asking for further specifications, can
pronounce this design absurd. Lana was prevented by his vow of poverty
from spending any money on experiment, so that he had to meet only
argumentative objections, not those much more formidable obstacles, the
ordeal of the inventor, which present themselves when a machine is
theoretically perfect and will not work. The difficulties which he
foresaw are real enough. The process of exhausting the air from the
globes might, he thought, prove troublesome. The pressure of the
atmosphere on the outer surface, it might be held, would crush or break
the globes, to which he replied that that pressure would be equal on all
sides, and would therefore rather strengthen the globes than break them.
The ship, some might object, could not be propelled by oars; Lana thinks
it could, but suggests, to comfort the objectors, that oars will rarely
be necessary, for there will always be a wind. The weight of the machine
and of the persons in it will fortunately prevent it from rising to
heights where breathing becomes impossible. 'I do not foresee', says
Lana, 'any other difficulties that could prevail against this invention,
save one only, which to me seems the greatest of them all, and that is
that God would never surely allow such a machine to be successful,
since it would create many disturbances in the civil and political
governments of mankind. Where is the man who can fail to see that no
city would be proof against surprise, when the ship could at any time be
steered over its squares, or even over the courtyards of
dwelling-houses, and brought to earth for the landing of its crew?...
Iron weights could be hurled to wreck ships at sea, or they could be set
on fire by fireballs and bombs; nor ships alone, but houses, fortresses,
and cities could be thus destroyed, with the certainty that the airship
could come to no harm as the missiles could be hurled from a vast
height.'

The extravagance of Lana's design must not be allowed to rob him of the
credit of being, in some sense, the inventor of the balloon. A balloon
filled with gas, and lighter than air, was in his day inconceivable; the
composition of the atmosphere was unknown, and the chemistry of