As the name shows, this is built on the principle of an insect.
It is well known that a body can be carried over the water much
faster than through it. With this in mind, builders at first
constructed light framework decks on large water-tight wheels or
drums, having paddles on their circumferences to provide a hold
on the water. These they caused to revolve by means of machinery
on the deck, but soon found that the resistance offered to the
barrel wheels themselves was too great. They therefore made them
more like centipeds with large, bell-shaped feet, connected with
a superstructural deck by ankle-jointed pipes, through which,
when necessary, a pressure of air can be forced down upon the
enclosed surface of water. Ordinarily, however, they go at great
speed without this, the weight of the water displaced by the bell
feet being as great as that resting upon them. Thus they swing
along like a pacing horse, except that there are four rows of
feet instead of two, each foot being taken out of the water as it
is swung forward, the first and fourth and second and third rows
being worked together. Although, on account of their size, which
covers several acres, they can go in any water, they give the
best results on Mediterraneans and lakes that are free from ocean
rollers, and, under favourable conditions, make better speed than
the nineteenth-century express trains, and, of course, going
straight as the crow flies, and without stopping, they reach a
destination in considerably shorter time.

Some passengers and express packages still cross the Atlantic on
'spiders,' but most of these light cargoes go in a far pleasanter
and more rapid way. The deep-displacement vessels, for heavy
freight, make little better speed than was made by the same class
a hundred years ago. But they are also run entirely by