ontracted in the fall of
the same year for five Hollands. The navy of almost every power
interested in submarines soon followed the lead of the British
Admiralty. Submarines of the Holland type were either ordered
outright, or else arrangements were concluded permitting the use of
the basic patents held by the Holland Company. It will be noted that
the United States Government having discovered that it had a good
thing benevolently shared it with the governments that might be
expected to use it against us.

[Illustration: Copyright by Munn & Co., Inc.

From the _Scientific American._

_Types of American Aircraft._]

The _Holland No. 9_, as her very name indicates, was one of a long
line of similar boats. As compared with other experimental submarine
boats she was small. She was only fifty-three feet ten inches long,
and ten feet seven inches deep. Although these proportions made her
look rather thickset, they were the result of experimental work done
by the builder during a period of twenty-five years. She was
equipped both with a gasoline engine of fifty horse-power and an
electric motor run by storage batteries. The latter was intended for
use when the boat was submerged, the former when she was travelling
on the surface of the water. She was capable of a maximum speed of
seven knots an hour. Her cruising radius was 1500 miles and the
combination of oil and electric motors proved so successful that
from that time on every submarine built anywhere adopted this
principle. Two horizontal rudders placed at the stern of the boat
steered her downward whenever she wanted to dive and so
accomplished a diver was this boat that a depth of twenty-eight feet
could be reached by her in five seconds. Her conning tower was the
only means of making observations. No periscopes had been provided
because none of the instruments available at that time gave
satisfaction. This meant that whenever she wished to aim at her
target it was necessary for her to make a quick ascent to the
surface. Her stability was one of her most satisfactory features. So
carefully had her proportions been worked out that there was
practically no pitching or rolling when the boat was submerged. Even
the concussion caused by the discharge of a torpedo was hardly
noticeable because arrangements had been made to take up the recoil
caused by the firing and to maintain the balance of the boat by
permitting a quantity of water equal to the weight of the discharg