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A Journey in Other Worlds

Dr. Cortlandt's History Continued
"In marine transportation we have two methods, one for freight and another for
passengers. The old-fashioned deeply immersed ship has not changed radically from the
steam and sailing vessels of the last century, except that electricity has superseded all
other motive powers. Steamers gradually passed through the five hundred-, six hundred-,
and seven hundred-foot-long class, with other dimensions in proportion, till their length
exceeded one thousand feet. These were very fast ships, crossing the Atlantic in four and
a half days, and were almost as steady as houses, in even the roughest weather.
"Ships at this period of their development had also passed through the twin and triple
screw stage to the quadruple, all four together developing one hundred and forty thousand
indicated horse-power, and being driven by steam. This, of course, involved sacrificing
the best part of the ship to her engines, and a very heavy idle investment while in port.
Storage batteries, with plates composed of lead or iron, constantly increasing in size, had
reached a fair state of development by the close of the nineteenth century.
"During the second decade of the twentieth century the engineers decided to try the plan
of running half of a transatlantic liner's screws by electricity generated by the engines for
driving the others while the ship was in port, this having been a success already on a
smaller scale. For a time this plan gave great satisfaction, since it diminished the amount
of coal to be carried and the consequent change of displacement at sea, and enabled the
ship to be worked with a smaller number of men. The batteries could also, of course, be
distributed along the entire length, and placed where space was least valuable.
"The construction of such huge vessels called for much governmental river and harbour
dredging, and a ship drawing thirty-five feet can now enter New York at any state of the
tide. For ocean bars, the old system of taking the material out to sea and discharging it
still survives, though a jet of water from force-pumps directed against the obstruction is
also often employed with quick results. For river work we have discovered a better
method. All the mud is run back, sometimes over a mile from the river bank, where it is
used as a fertilizer, by means of wire railways strung from poles. These wire cables
combine in themselves the functions of trolley wire and steel rail, and carry the
suspended cars, which empty themselves and return around the loop for another load.
Often the removed material entirely fills small, saucer-shaped valleys or low places, in
which case it cannot wash back. This improvement has ended the necessity of building
jetties.
"The next improvement in sea travelling was the 'marine spider.' 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-
 
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