son was engaged during the twelve years of his life in London. In
connection with some he was undoubtedly a pioneer, and deserves credit
as an original inventor; in connection with others, his work was that of
improvement or adaptation; but in all his influence was profound, and
the legacy which we have received from this period of engineering
progress is due in no small degree to Ericsson, and to his work in
London during these years. At a later point we shall refer in some
further detail to these questions, but desire for the moment, rather, to
gain a broad and comprehensive view of his life as a whole.

Ericsson has been by some called a spendthrift in invention, and the
term is not without some justice in its application. His genius was
uneasy, and his mind was oppressed by the wealth of his ideas. It was
this very wealth which led him from one idea to another, without always
taking sufficient time in which to develop and perfect his plans. Rich
in invention, he cared but little for exploitation, and when the truth
of his predictions was demonstrated, or the ground of his expectation
justified, he was eager for new achievements and new combinations of the
materials of engineering progress. In this spirit of struggle and
unrest, he passed the years in London, rapidly becoming known for his
versatility in invention, and for his daring and originality in the
details of his engineering work. From 1833 to 1839, or during the second
half of this term of residence in London, he became in increasing
measure absorbed in his work connected with the screw-propeller as a
means of marine propulsion.

Ericsson's name in the popular mind has been most commonly associated
with the "Monitor" and her fight with the "Merrimac" in the Civil War,
and next, probably, with the screw-propeller as a means of marine
propulsion. It will, therefore, be proper at the present point to refer
in some further detail to the circumstances connected with his relation
to the introduction of the screw-propeller.

Regarding this question an entire volume might be written without doing
more than justice to the subject, but only a brief statement of the
chief facts can be here attempted.

As early as the Seventeenth Century the possibility of developing a
propulsive thrust by the use of a submerged helicoidal, or screw,
propeller, had been vaguely recognized, and during the following, or
Eighteenth Century, the same idea had been brought forward. It had