supply five electrical horse power for the time stated, and these 47
cells will weigh 2,633 lb.

We could employ half the number of cells by using them at the rate of
80 amperes, but then they will supply the power for less than half the
time. The fact, however, that the cells will give so high a rate of
discharge for a few hours is, in itself, important, since we are enabled
to apply great power if desirable; the 47 cells above referred to can
be made to give 10 or 12 electrical horse power for over two hours, and
thus propel the boat at a very high speed, provided that the motor is
adapted to utilize such powerful currents.

The above mentioned weight of battery power--viz., 2,632 lb., to
which has to be added the weight of the motor and the various
fittings--represents, in the case of a steam launch, the weight of
coals, steam boiler, engine, and fittings. The electro motor capable of
giving four horse power on the screw shaft need not weigh 400 lb. if
economically designed; this added to the weight of the accumulators, and
allowing a margin for switches and leads, brings the whole apparatus up
to about 28 cwt.

An equally powerful launch engine and boiler, together with a maximum
stowage of fuel, will weigh about the same. There is, however, this
disadvantage about the steam power, that it occupies the most valuable
part of the vessel, taking away some eight or nine feet of the widest
and most convenient part, and in a launch of twenty-four feet length,
requiring such a power as we have been discussing, this is actually
one-third of the total length of the vessel, and one-half of the
passenger accommodation; therefore, I may safely assert that an electric
launch will carry about twice as many people as a steam launch of