Wave action

“ The motion of the particles of the water in a deep-sea wave resembles that of the white knobs in the model described. Those who swim will recall to mind their sensations as a sea wave surges over them. The wave [6] lifts up the swimmer, then pushes him a little forward, then lets him down, and, lastly, drags him back. It is this dragging-back action which is so dangerous to persons who cannot swim, when they are bathing on a steep coast where strong waves are rolling in towards the shore. ”

“ A sound signal emitter comprising a resonator having an orifice of suitable shape such that when a jet of air is passed through the orifice the turbulence produces a sound.
whistle buoy. A sound buoy equipped with a whistle operated by wave action. The whistle makes a loud moaning sound as the buoy rises and falls in the sea.
whitecap, n. A crest of a wave which becomes unstable in deep water, toppling over or “breaking.” The instability is caused by the too rapid addition of energy from a strong wind. A wave which becomes unstable due shallow water is called a BREAKER.
white ice. ”

“ The box has two pipes connected with it, by means of which it can be filled with carbonic acid gas.
Provided with this apparatus, it is now possible to show you a series of experiments which will leave no doubt in your minds that the external agency which creates in us the sensation of sound is a wave-motion in the air we breathe. Let me, in the first place, show you that a sound-beam can be reflected. We adjust our sensitive flame and set the whistle in action, and create, as described, by the lens, a beam of sound. ”

“ WE have all stood many times by the seashore, watching the waves, crested with white foam, roll in and break upon the rocks or beach. Every one has more than once cast a stone upon still water in a lake or pond, and noticed the expanding rings of ripples; and some have voyaged over stormy seas, whereon great ships are tossed by mighty billows with no more seeming effort than the rocking of a cradle. In all these things we have been spectators of a wave-motion, as it is called, taking place upon a water surface. ”

“ The rhythm of waves beats in the sea like a (48) pulse in living flesh. It is pure force, forever embodying itself in a succession of watery shapes which vanish on its passing.
I stand on my dune top watching a great wave coursing in from sea, and know that I am watching an illusion, that the distant water has not left its place in ocean to advance upon me, but only a force shaped in water, a bodiless pulse beat, a vibration.
Consider the marvel of what we see. Somewhere in ocean, perhaps a thousand miles and more from this beach, the pulse beat of earth liberates a vibration, an ocean wave. ”

“ The creation of the waves will bring it to rest in time, unless it is continually urged forward by some external and impressed force, and wave-generation is a reason for a part at least of the resistance we experience when we attempt to push it along. ”

“ Fastening our attention for the moment on surface water waves, the first question we shall ask ourselves is—What is a wave? If we take our station on a high cliff looking down on the sea, on some clear day, when the wind is fresh, we see the waves on its surface like green rounded ridges racing forward, and it appears at first sight as if these elevations were themselves moving masses of water. ”

“ In all departments of natural science we find ourselves confronted by the phenomena of wave-motion. In the study of earthquakes and tides, telegraphs and telephones, as well as terrestrial temperature, no less than in the examination of water waves and ripples, sound, music, or light and heat, we are bound to consider waves of some particular kind. ”

“ As a wave progresses over the surface, wave-energy is continually being imparted to portions of the water in front, and it is transferred away from others in the rear. In the very act of setting a fresh particle of water in oscillation, the portions already vibrating must diminish their own motion. They may hand on the whole of their energy or only a part of it to their neighbours. This distinction is a very important one, and it determines whether a single act of disturbance shall create a solitary wave or wave-train in a medium. ”

“ A careful observer can in this school of Nature instruct himself in all the laws of wave-motion, and gather a fund of knowledge on this subject during an hour’s dalliance at low tide on some sandy coast, or in the quiet study of seaside pools, the surface of which is corrugated with trains of ripples by the breeze. ”

“ A person who has been at sea, may almost fancy that he hears the resounding dash of the water against the curved bow, and the seething of the angry wave as it rises on each side. The idea of motion is admirably conveyed in the representation of the wave lashing over the floating mast, which is tossed about like a light spar by the violence of the sea; and the continued inward roll of the water, from the side and bow of the boat towards the shore, is no less naturally expressed. ”

“ For, see, since a wave is only a communicated agitation or impetus, and since the water that composes a wave is changing every instant, new water is rising into the wave as fast as the wave travels. You slide down this new water, and yet remain in your old position on the wave, sliding down the still newer water that is rising and forming the wave. You slide precisely as fast as the wave travels. If it travels fifteen miles an hour, you slide fifteen miles an hour. Between you and shore stretches a quarter of mile of water. ”

“ No matter how fiercely the waves are running, let the wind lull, and a brisk rain of an hour will take all the rough edge off them. It is the dashing and breaking waves that sailors dread. A regular swelling wave, no matter how high it towers, will do no harm, as a vessel will rise with it, and ride lightly over. ”

“ Their chief object has been to show you that the swiftly moving ocean waves, which dash and roll unceasingly against the coast-lines of our island home, are only instances of one form of wave-motion, of which we find other varieties in other media, giving rise to all the entrancing effects of sound and light. In these expositions we have been able to do no more than touch the fringe of a great subject. ”

“ We are led, therefore, to infer that, even when agitated by waves, each particle of water never moves far from its position when at rest, and that the real movement of the water is something very different from its apparent motion. If we place on the surface of water a number of corks or pieces of paper, and then watch them as a wave passes over them, we shall notice that the corks or bits of paper rise and fall successively, that is, one after the other, and not all together. ”

“ The wave which is breaking into foam, which is rippling over the pebbles, which throws up the broken water, which falls back on to the land and makes music, sound, melody as it breaks—that is the wave which is nearly over; it is the wave whose course is run. ”

“ I saw the worst assault at night on a seaside parade where the sea smote on the doors of England with the hammers of earthquake, and a white smoke went up into the black heavens. There one could thoroughly realise what an awful thing a wave really is. I talk like other people about the rushing swiftness of a wave. But the horrible thing about a wave is its hideous slowness. ”

“ The waves which spread round a central point when a stone is thrown into the water, give one the idea that the water which forms the wave really moves towards the observer. But it is not so, as may be readily proved by placing on the surface a floating body, which we shall find is but little, if at all, influenced by the undulations of the water. The appearance of rolling waves given on the stage by means of a painted cloth, to which an undulatory motion is given, is an instance of this apparent movement. ”

“ Other parts of the water are at the average level of the sea, but are moving with considerable velocity, and these portions possess energy of motion. Every other part of the wave has in some degree both energy of motion and energy of position, and it can be shown that the energy of the whole wave is half of one kind and half of the other. ”

“ If the liquid space is free, the vibrations are gradually extinguished; if they meet an obstacle, there is a shock. If the obstacle is a shore, they form a tidal-wave and raise large billows, while a few miles away from the shore the sea is quiet. When the obstacle is a shoal or a contrary vibration, heavy waves are raised on the surface of the sea; they seem to start from the bottom, and put ships in great danger. The waves produced in both cases are waves of transmission, as also are those which beat on reefs in pleasant weather, and those which prolong the swell after storms. ”

“ You climb wave after high wave, and are not swallowed up as you expected. You wait, between guns, for the boom and the shock of the next, with a passionate anticipation, as you wait for the next wave. ”

“ Now, the velocity of wave propagation can be seen, without the aid of any mathematical analysis, to depend on the elasticity of the medium and its density; for we can see that if a medium is highly elastic the disturbance would be propagated at a great speed. ”

“ No artist had ever before studied the wave motions in an exact and scientific manner, so as to understand the relations of one wave to another and of all to the undercurrents and the wind and the tide, and all those varied forces which make the water on one shore, or under one sky, so different from the water on another shore or under another sky. ”

“ Waves pass across the surface of the sea and successive waves are not the same, nor is what we call the same wave really the same at two different points in its progress, and yet one wave causes another wave and transmits its form and movement. ”

“ If two infinitely long sets of deep-sea waves, having slightly different wave-lengths, and therefore slightly different velocities, are superimposed, we obtain a resultant wave-train which exhibits a variation in wave-amplitude along its course periodically. ”

“ We see a wave a quarter of a mile off, then a few hundred yards nearer in, then just offshore; we seem to have been watching the same travelling mass of water—there has been no appreciable change in mass or in shape—yet all the while the original beat has taken on a flowing series of liquid bodies, bodies so alike, so much the same, that our eye will individualize them and follow them in—the third wave, we say, or the second wave behind the great wave. ”

“ The whole theory of the trail of waves made by a canal-boat is only comprehensible if it is clearly seen that a water-surface wave has a certain velocity determined by its wave-length. If the wave-speed is small, the waves are short. As the speed increases the waves get longer. Or the matter may be put in another way. We may say that just as a pendulum has a certain rate of vibration depending on its length, so a water wave has a certain frequency, and therefore, a certain speed of propagation dependent upon the wave-length, or shortest distance from one wave-crest to the next. ”

“ When the waves leave the generating area and continue as free waves, the wavelength and period continue to increase, while the height decreases. The rate of change gradually decreases. The speed (S) of a free wave in deep water is nearly independent of its height or steepness. ”

“ The total volume of water which is comprised in the space occupied by even one sea-storm wave of moderate dimensions may have a mass of many hundreds of tons, and its energy of motion may easily amount to that of an express train in motion. ”

“ When two trains of sound waves travel through the same medium, each particle of the air, being simultaneously affected by the disturbances due to the different waves, moves in a different manner than it would if only acted on by each wave singly. ”

“ The most important and easily observed of the four sets of waves is the oblique bow wave. It is most easily seen when a boy’s boat skims over the surface of a pond, and readily observed whenever we see a duck paddling along on the water. Let any one look, for instance, at a duck swimming on a pond. He will see two trains of little waves or ripples, which are inclined at an angle to the direction of the duck’s line of motion. ”

“ Since the incoming wave affects water which is at the same time under the influence of the undertow, it gives to that current a pulsating character, for the wave-motion sometimes supports and sometimes opposes the undertow, and thus endows it with a higher transporting power than belongs to its mean velocity. ”

“ Besides the forms of the simple rising and falling intervals in which the concrete is generally uttered, there is another form, called the wave, effected by a union of these modes. It is of two varieties: (1) where a rising movement is continued into a falling movement, called the direct wave; (2) where a falling movement is continued into a rising movement, called the inverted wave. ”

“ Water is fluid, and the upper part of the wave not having been stopped, it keeps on communicating its agitation, and moves on shoreward. Ergo,” says he, “something is bound to be doing when the top of a wave keeps on after the bottom has stopped, dropped out from under. ”

“ No matter how the disturbance is first set up, whether by the sun, or by a dynamo, or by a warm flat-iron, in every case the ether conveys nothing at all but the energy of wave-motion, and when the waves, encountering some material obstacle which does not reflect them, become quenched, their energy takes another form, and some kind of work is done, or heat is generated in the obstacle. ”

“ This is a conception which is not obvious to common apprehension. It appears paradoxical at first sight to speak of a large wave (as the tide-wave) running up a river at the rate of twenty miles an hour, while the stream of the river is all the while flowing downwards. Yet this is a very common fact. And the conception of such a motion must be fully mastered by all who would reason rightly concerning the mechanical transmission of impressions through a medium. ”