ller of this size would make about thirty
gallons of fresh water per day. Very frequently a distiller, such as is
shown in the sketch, is mounted separately, and placed near the winch or
donkey boiler, which supplies it with steam, the lower part, F, being
then used as a filter. The diameter of E is from 15 in. to 18 in., the
outer casing being either iron or copper. Another form of distiller is
one like the above, but larger, and having a small donkey engine and
circulating pump attached thereto. As a rule these distillers are
vertical, but larger apparatus are arranged horizontally. To give our
readers some general idea of size, weight, and produce of water, we may
say that a plain cylindrical distiller, mounted on a square filter case,
measuring 3 ft. 9 in. high, weighing 41/2 cwt., will distill twelve gallons
per hour. A larger size, measuring 6 ft. 2 in. high, and weighing about
23 cwt., will give 85 gallons; while a still larger one, measuring 7 ft.
high and weighing 32 cwt., yields 150 gallons. These have no pumps. When
an engine and pump are fitted, the weight is increased from about 80 per
cent. in the smaller to 50 per cent. in the larger sizes. An immense
advantage attends the use of those distillers that are combined with a
winch boiler. Of course, the chief use of the winch is while in dock;
some use is made of it at sea to do heavy pulling and hauling, to wash
decks, and in case of emergency the circulating pump is used as a fire
engine. Were it not, however, for the distiller, the winch boiler would
simply be idle lumber at sea. The distiller, however, finds useful
employment for it, and has also this excellent effect, that as steam is
pretty constantly kept up for the distiller, in the evil event of a fire
the boiler is ready to work at once. In horizontal types of distiller an
engine and pump are mounted on a cast iron casing as a bed, and in this
casing is placed a number of tubes through which the steam passes to be
condensed, the whole being simply a surface condenser with engine and
pump above. Another type is that of a small single-flued horizontal
boiler with combustion chamber and twenty or thirty return tubes--in
fact, the present high-pressure marine boiler on a small scale. A boiler
of this sort, measuring 4 ft. to 5 ft. long, 3 ft. 9 in. to 4 ft. 6 in.
diameter, would have a horizontal donkey engine on a bed at its side, and
at the end of the engine a vertical cylindrical condenser.

[Illustra