Meanwhile he applied himself with his accustomed energy to the
practical working out of another favorite idea. The principle of the
Ericsson propeller was first suggested to the inventor by a study of
the means employed to propel the inhabitants of the air and deep. He
satisfied himself that all such propulsion in Nature is produced by
oblique action; though, in common with all practical men, he at first
supposed that it was inseparably attended by a loss of power. But when
he reflected that this was the principle invariably adopted by the
Great Mechanician of the Universe, in enabling the birds, insects, and
fishes to move through their respective elements, he knew that he must
be in error. This he was soon able to demonstrate, and he became
convinced, by a strict application of the laws which govern matter and
motion, that no loss of power whatever attends the oblique action of
the propelling surfaces applied to Nature's locomotives. After
having satisfied himself on the theory of the subject, the first step
of the inventor was the construction of a small model, which he tried
in the circular basin of a bath in London. To his great delight, so
perfectly was his theory borne out in practice, that this model, though
less than two feet long, performed its voyage about the basin at the
rate of three English miles an hour.

The next step in the invention was the construction of a boat forty
feet long, eight feet beam, and three feet draught of water, with two
propellers, each of five feet three inches in diameter. So successful
was this experiment, that, when steam was turned on the first time, the
boat at once moved at a speed of upwards of ten miles an hour, without
a single alteration being requisite in her machinery. Not only did she
attain this considerable speed, but her power to tow larger vessels was
found to be so great that schooners of one hundred and forty tons'