the stability of boats such as this, having their engine, boiler, supply
of coal, forty passengers who might all occupy one side of the vessel, a
central superstructure, with roof; and, finally, all the weight centered
on five feet of the deck, with nothing below to counterbalance it except
the hollow hulls and two three-foot compartments, each placed toward the
central portion of the hulls and designed as fresh-water reservoirs
for the steam generator. The second difficulty was to obtain the best
utilization possible of a screw placed in the current between the hulls
and upon a shaft inclined toward the stern, that is, "stern" by analogy,
for there is no distinction of fore and aft in ferry boats.

[Illustration: STEAM FERRYBOATS OF THE PORT OF MARSEILLES.]

The conditions of the problem were finally fulfilled to the satisfaction
of all concerned, and especially to that of the public.

The hulls, navicular in form and having a flat bottom, are constructed
of one-tenth inch iron plate and 40x40 angle iron. Their dimensions
are: Length, 33 feet; breadth, 31/4 feet; and depth, 5 feet. The internal
distance between the two shells is 71/4 feet. These hulls, having
absolutely water-tight decks, are connected below by tie bars of flat
iron, and above by vertical stays 1 foot in length, which serve to
support the floor-planks of the deck and boilerplate flooring of the
engine-room. The engine-room, which is 191/2 feet long by 5 feet wide, is
constructed of varnished pitch-pine, with movable side-shutters of teak.
The roof, of thin iron plate, is provided with a ventilator to allow of
the escape of hot air.

The passengers, to the number of forty or fifty, can move about freely
from larboard to starboard, or from stem to stern, or seat themselves