similar dimensions.

The diagram on the wall represents sections of an electric launch built
by Messrs. Yarrow and Company, and fitted up by the Electrical Power
Storage Company, for the recent Electrical Exhibition in Vienna. She has
made a great number of successful voyages on the River Danube during the
autumn. Her hull is of steel, 40 feet long and 6 feet beam, and there
are seats to accommodate forty adults comfortably. Her accumulators are
stowed away under the floor, so is the motor, but owing to the lines of
the boat the floor just above the motor is raised a few inches. This
motor is a Siemens D2 machine, capable of working up to seven horse
power with eighty accumulators.

In speaking of the horse power of an electro motor, I always mean the
actual power developed in the shaft, and not the electrical horse power;
this, therefore, should not be compared to the indicated horse power of
a steam engine.

I am indebted to Messrs. Yarrow for the principal dimensions and other
particulars of a high pressure launch engine and boiler, such as would
be suitable for this boat. From these dimensions I prepared a second
diagram representing the steam power, and when placed in position it
will show at a glance how much space this apparatus will occupy. The
total length lost in this way amounts to 12 feet, leaving for testing
capacity only 15 feet, while that of the electric launch is 27 feet
on each side of the boat; thus the accommodation is as fifteen to
twenty-seven, or as twenty-two passengers to forty, in favor of the
electric launch.

Comparing the relative weights of the steam power and the electric power