gnificance of his life and services for his adopted land and for
the world at large.

The two pieces of work which perhaps will be most permanently linked
with the name of Ericsson are the screw-propeller as a means of marine
propulsion, and the "Monitor" as a type of warship. In addition to
these, however, his life-work was rich in results which bore direct
relation to many other improvements in the broad field of marine
engineering and naval architecture. Of these a few of the more important
may be mentioned, such as the surface condenser, distiller, and
evaporator, forced draft for combustion, placing machinery of warships
below the water-line, and their protection by coal, ventilation by
fan-blowers, together with a vast variety of items involved in the
conception and design of the "Monitor" as a whole, and in his other
naval designs.

In order to appreciate the influence of Ericsson's life and work on the
field of marine construction, a brief glance may profitably be taken at
this branch of engineering work as it was before Ericsson's time, and as
it is now.

The material employed for shipbuilding was almost entirely wood. This
was displaced in the 'sixties and 'seventies by iron, which in turn was
displaced by steel, so that at the present time, except for special
reason, no material other than steel is thought of for this purpose.
With the gradual displacement of wood by iron in the mercantile marine,
Ericsson's relation was only indirect. Some of the earlier mercantile
vessels in which he was interested were of wood and some of iron. In the
field of warship construction, however, his influence through the
"Monitor" was more direct, especially as to the value of metal armor as
a protection against great gun-fire. Still, it is no more than justice
to say that with the change from wood to iron which took place during
the active part of his life, Ericsson had only an indirect relation, and
the change would doubtless have come about at the same time, and in much
the same general way as it did, independent of any influence which his
work may have had upon the question. Turning to the means of propulsion,
we find sails as the main, or almost only, reliance during the early
years of the century. The steam-engine operating paddle-wheels had come
to be recognized as a possibility, and under certain conditions as a
commercial success. The screw-propeller as a means of propulsion was
known only as a freak idea, and was w