whirling in the breeze.

To stop the _Turbina_ was an easy matter; Mr. Parsons had only to turn
off the steam. But to make the vessel go backward another set of
turbines was necessary, built to run the other way, and working on the
same shaft. To reverse the direction, the steam was shut off the engines
which revolved from right to left and turned on those designed to run
backward, or from left to right. One set of the turbines revolved the
propellers so that they pushed, and the other set, turning them the
other way, pulled the vessel backward--one set revolving in a vacuum and
doing no work, while the other supplied the power.

The Parsons turbine-engines have been used to propel torpedo-boats, fast
yachts, and vessels built to carry passengers across the English
Channel, and recently it has been reported that two new transatlantic
Cunarders are to be equipped with them.

[Illustration: THE ENGINES OF THE _ARROW_]

A few years after the Pilgrims sailed for the land of freedom in the
tiny _Mayflower_ a man named Branca built a steam-turbine that worked in
a crude way on the same principle as Parsons's modern giant. The
pictures of this first steam-turbine show the head and shoulders of a
bronze man set over the flaming brands of a wood fire; his metallic
lungs are evidently filled with water, for a jet of steam spurts from
his mouth and blows against the paddles of a horizontal turbine wheel,
which, revolving, sets in motion some crude machinery.

There is nothing picturesque about the steel-tube lungs of the boilers
used by Parsons in the _Turbina_ and the later boats built by him, and