ed into a rotary
motion of the shaft. In particular, he was the first to introduce and
show the advantages of engines directly connected to the
propeller-shaft, instead of through the more indirect and clumsy modes
which others had previously thought necessary.

Aside from his relation to the screw-propeller, perhaps no item of his
work in connection with the steam-engine is of more importance than the
surface condenser, with its variant forms in the distiller and
evaporator. If Ericsson had done nothing else, his claims to recognition
and remembrance as an engineer and benefactor might have been well
founded on his work in this connection. As it is, the fact that he was
so largely instrumental in their perfection and adaptation to marine
uses is wellnigh forgotten in the brighter light of his other
achievements.

Regarding Ericsson's relation to the successful introduction of the
screw-propeller, little need be added to what has already been said.
Whatever may be urged regarding dates and patents or earlier years in
which the screw-propeller was used, it is a fact that in 1833-35 it was
not recognized as an accepted mode of propulsion. While known as a
possibility, it had no standing in the engineering practice of the day.
A few years later it was recognized as an accepted mode of propulsion
and had gained a permanent and definite place in the practice of the
day,--a place which has continued to grow in importance until its
earlier rival, the paddle-wheel, is almost on the brink of relegation to
museums of antiquities, except possibly for rare and special
shallow-water uses. A careful and dispassionate study of the facts, so
far as they can be known at the present time, seems to indicate clearly
that of those who were concerned in successfully adapting the
screw-propeller to the needs of marine propulsion and in laying the
foundation for these changed conditions, especially in the United
States, none was so prominent as Ericsson, or so fairly deserving of the
chief credit; and with this judgment the mature thought of the present
day seems to agree with little dissent.

Turning to a consideration from a similar point of view of Ericsson's
services in connection with warship design and construction, note may be
first taken of the condition of the art of naval warfare in the years
1840-50, or when Ericsson first began his labors in this field.

The material used was wood, the means of propulsion sails, with some
thou