Regarding the change from wind to steam for the motive-power of ships, Ericsson did his full share among the engineers of his day, but it would be unfair to many others to claim for him any exclusive or preponderating influence in this movement, and in such matters it is difficult to clearly define the services of any one man. The lines of progress, however, have been in accord with his studies, and his work has certainly had a most direct and powerful influence upon the movement. The most important points of contact between Ericsson's work and these advances were in connection with his introduction of the surface condenser, the use of artificial draft, devices for heating feed water, his studies in superheated steam and its use, and his work in connection with the development of the compound principle in steam-engines, his relation to the introduction of the screw-propeller, and to the use of twin screws at a later time. He also devised and adapted many new types of engines for marine purposes, having respect to the geometrical character of the connections by means of which a reciprocating motion of the piston may be transformed 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.