The cold water, which is forced through by a circulating pump, enters
at the bottom, and is compelled to pass forward through the lower set
of tubes by a horizontal dividing plate; it then returns through the
upper rows of tubes and passes out at the overflow; the tubes are thus
maintained at a low temperature.
The tubes are made to pass right through the condensing chamber, and so
as to have no connection with its internal space. The steam is passed
into the condenser and there comes in contact with the cold external
surface of the tube, and is condensed, and removed as before, by the
air pump, as may be readily seen in the illustration (p. 65.)
The advantages gained by the use of the surface condenser are: 1. The
feed water is hotter and fresh; being hotter, it saves the fuel that
would be used to bring it up to this heat; and being fresh it boils at
a lower temperature. 2. Not forming so much scale inside the boiler,
the heat passes through to the water more readily; and as the scum cock
is not used so freely, all the heat that would have been blown off is
saved. Its disadvantages are that being fresh water and forming no
scale on the boiler, it causes the boiler to rust.
It is often said that one engineer will get more out of a ship than
another. In general it will be found that the most successful engineer
is the man who manages his stokers best. It is very difficult on
paper to define what is meant. It is a thing to be felt or seen, not
described. * * * * The engineer who really knows his business will give
his fires a fair chance to get away. He will work his engines up by
degrees and run a little slowly for the first few moments.