THE "NORTH POLE" BALLOON
 

395
 

not increase at the same rate as the surface. When the diameter
of the sphere is doubled, its volume becomes eight times greater, but
its surface is only quadrupled. It is the battle of cubes against
squares that demonstrates that the larger a balloon is the better it
is. Nevertheless, there is a certain limit which the maker should
not exceed. Moreover, the larger a balloon, the greater resista,nce
its stuff can offer. Hence the envelope of the North Pole possesses
considerable tenacity—much greater than could be given to an
aerostat of smaller dimensions—and relatively to the ascensional
power at our disposal, this envelope is lighter than that of a small
balloon made of gold-beater's skin.

But aU these advantages demand greater attention on the part
of those who manage the balloon, for the consequences of error
with a large balloon are much more serious than with a small one.
For instance, if we allow the immense machine to take an improper
amount of descent, it may be impossible to arrest its downward
course in time. Thus it happens that aeronauts who are ignorant
of physical principles are by no means fond of large balloons, for
they have ever before their eyes the consequences of inevitable
errors. These slaves of routine are much in the position of the
master of a small fishing-smack to whom the management of the
Greed Eastern might be confided.
 

THE   CAR   OF   THE   " NORTH  POLE."