276
Molesworth’s pocket-book
Waves.
■ A wave may travel without force to maintain
its motion, provided it be long in proportion tu
the depth of the fluid.
2. When the length of a wave is not greater
than the depth of the water, the velocity of the
wave depends (sensibly) only on its length, and
is proportional to the square root of its length.
3. When the length is not less than 1000 times
the depth of the water, the velocity depends only
on the depth, and is the same as the velocity which
a free body would acquire by falling throuo-h a
height = half the depth of the water.
4. 1 or intermediate proportions, the velocity can
only, be obtained by a general equation. Under
no circumstances does an unbroken wave exceed
30 or 40 feet in height. A wave breaks when its
height above the general level of the water is equal
to the general depth.—Prof. Airev, ‘Encvdon
Metrop.,’ “ Tides.” 1
V = Velocity of wave in feet per second.
T = Time of wave in seconds.
D = Depth of water in feet.
II = Height of wave in feet.
L = Length of wave in feet.
when L is less than D.
V = V 32-17 D when L exceeds 1000 D.
— ^///32-17D (1 + 3^ j when the height
of the wave bears a sensible proportion to
the depth.
T — -55 VL )
V = 1-818 a/L J