he steam goes through the holes of an intervening fixed
partition that deflects it so that it blows afresh on the second, and so
on to the third and fourth, blowing upon a succession of wheels, each
set larger than the preceding one. Each of Parsons's steam-turbine
engines is a series of turbines put in a steel casing, so that they use
every ounce of the expansive power of the steam.

It will be noticed that the little wind-turbine that you blow with your
breath spins very rapidly; so, too, do the wheels spun by the steamy
breath of the boilers, and Mr. Parsons found that the propeller fastened
to the shaft of his engine revolved so fast that a vacuum was formed
around the blades, and its work was not half done. So he lengthened his
shaft and put three propellers on it, reducing the speed, and allowing
all of the blades to catch the water strongly.

The _Turbina_, speeding like an express train, glided like a ghost over
the water; the smoke poured from her stack and the cleft wave foamed at
her prow, but there was little else to remind her inventor that 2,300
horse-power was being expended to drive her. There was no jar, no shock,
no thumping of cylinders and pounding of rapidly revolving cranks; the
motion of the engine was rotary, and the propeller shafts, spinning at
2,000 revolutions per minute, made no more vibration than a windmill
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