277
OF ENGINEERING FORMULÆ.
Waves—continued.
Mr. Scott Russell divides waves into two
classes:—
Waves of translation, or of the 1st order.
„ oscillation, „ 2nd „
WAVES OF THE 1ST ORDER.
1. Velocity not affected by the intensity of the
generating impulse.
2. Motion of the particles always forward in
the same direction as tiie wave, and the same at
the bottom as at the surface.
3. Motion of the particles most intense in a
vertical lino below the crest; the particles at rest
in the trough.
4. Character of the wave, a prolate cycloid in
long waves, approaching a true cycloid as the
height of the wave approaches the proportion of
Ird of its length. When the height is more
than |rd of the length, the wave breaks.
WAVES OF THE 2ND ORDER.
1. Ordinary sea waves are waves of the 2nd
order, but become waves of the 1st order as they
enter shallow water.
2. Character cycloidal.
3. Motion of water alternately flowing to and
from a point. Towards the top of the wave the
movement of particles is in the direction of the
wave; but in the trough the movement is in
the opposite direction.