Beach Rambles in Search of Seaside Pebbles and Crystals / With Some Observations on the Origin of the Diamond and Other Precious Stones

by John George Francis

Let us speak first of the power of the WIND. The sands of the Desert, as has been said, are powdered quartz and quartz is a heavy substance; but when a strong wind ploughs the surface of the Desert at an angle, these Sands are lifted, and made to gyrate in spiral folds, and a huge column is formed—perhaps a hundred and fifty feet in height—and this monstrous trunk is presently carried along at whirlwind speed; and if it meet a party of travellers, they will be overwhelmed and buried.

It may be said that the sand is in very minute particles; and this is true. But if they are, therefore, the more easy to disturb and to catch up aloft, they are all the more difficult to bind together in a spiral form, and to hurry along the desert unbroken.

The power of the wind, especially when it comes in sudden gusts, and with a whirling motion, against timber-trees and the upper parts of buildings, is only too well known; on wide, exposed plains, its fury, in the early part of the year, sometimes brings destruction to everything within its range. But it is on the open sea, where the hurricane, once let loose from heaven, can sweep, unchecked, perhaps for hundreds of miles, that the latent forces of this unseen element are revealed in all their terror and majesty. For here the wind not only has free scope, but it also finds another element, fluid but incompressible, to obey its impulse and follow in the course which it takes. If the WIND be like a wild spirit, the WATER is a mighty, irresistible body, endowed with motion by the other, and capable of any work, from the drowning of a sea-gull to the wrecking of a stately ship.

The waves which roll in from the open sea, when the tide is making, are the most powerful. Fortunately, these do not reach the shore with quite the same force which they exert at the distance of some miles from it; but in exposed situations, their altitude and momentum are very great. The billows of the Atlantic which break on the western coast of Ireland run from thirty feet to fifty feet in height, and they arrive on that coast with an impetus which has (up to a certain point) been gaining strength, perhaps for half the time of a tide. It was this fearful onset, from a foe that never slumbered, which broke up and rendered useless the eastern extremity of the great Submarine Electric Telegraph Cable between Ireland and America.

It has now been decided that when stormy winds prevail long in one direction, another and peculiar force is given to the waves on which they operate. For the wind, by pressing long on the side of a wave, changes its form from that of an upright ridge (i.e. with vertical axis) to one which has a stoop or bend, sometimes of great inclination. Such a wave will come in upon the shore with far greater momentum, for its velocity has been enormously increased, while its bulk is nowise diminished. The speed which the water acquires under the influence of a prolonged sou’-wester on the coasts of Sussex and Hampshire, although there the gale has only traversed the breadth of the Channel, is very notable at times. At Lowestoft and at Peterhead, easterly points of land, the danger of the winds from the North Sea is proportionally far greater, as a larger body of water has been continuously acted upon. For it must always be remembered that a wave at sea is simply an oscillation of the water which rises and falls in that place. The identical wave does not pass on to the shore, though it appears to do so; it is the motion which is propagated, and, as it were, handed on, like an electric shock through the successive plates of a battery. Now this motion increases with the onward career of the gale. “Vires acquirit eundo.” And when the mass of the fluid over which the wind is blowing has once been agitated, and the equilibrium of its upper layers been thoroughly disturbed, if the current of air not only continue, but wax stronger and stronger, there scarcely seems any limit to the momentum which the rolling wave may thus acquire. The arithmetic of a few facts upon this subject will, however, give us some idea of what that momentum must be on certain occasions.

It has been found, by experiment, that the velocity imparted to an incoming wave sometimes equals seventy feet in a second of time. Now this would give nearly one mile in a minute, if it were a projectile in free space; but the case here is, of course, different, since the wave is only a portion of the mass to which it belongs, and no individual wave travels very far. Still, the amount of rush and pressure which are exerted is altogether stupendous. Probably the breakers, which in an enduring storm rise against a lighthouse in the open sea, are among the strongest instances with which we are acquainted, and, next to these, I suppose, the billows off the Cape of Good Hope. But we may take those on the Irish coast, westward, as a well-known sample. I have often watched these—once in a gale of wind—and I have seen, in one as yet unbroken wave, a body of water which I should compute roughly at two hundred tons’ weight, and as having, at the moment, a velocity of not less than sixty feet in the second, discharge itself upon the reef of rock. On such occasions, if you happen to stand on the shore, you will feel the ground vibrate apparently, though the sensation is probably electrical. But let any one consider the conditions of the wave cited above, and reckon what is the force of the blow at the moment of impact. I have no doubt it would knock down a good strong house, if delivered against the upright face of it.

One winter, when I was at Sandown, in the Isle of Wight, a spot frequently mentioned in these pages, I found I was utterly unable to traverse the bit of open road reaching from the Fort to the point where the lane turns off to Yaverland. Yet I had on at the time a stout Cording’s waterproof, with sleeves, and a slouched hat tied under my chin, and held a powerful oaken stick in my hand to help me win my way. In fact, it was a trial of dynamics between me and the gale, whether this “body,” acted on by a continuous muscular force, in nearly a right line, could be propelled through that resisting medium. I am sorry to say, it could not; but, in the attempt, it lost a neck-button from its coat, and was within an ace of being blown into the hedge, like a certain “man in Thessaly, wondrous wise,” whom we have heard tell of in our childhood.

This storm held on for seven or eight hours, and as the sea rose many feet higher than usual under its influence, when the tide was well in, the strife of elements, and their combined assault upon the works of men’s hands were truly grand. A breach was made through the solid causeway, compact long ago of clay, and gravel, and boulders of flint, and guarded seaward by dykes of timber. This breach was effected, I have no doubt, by the stroke of the wave, as the sword of Roland is said to have cut through the rock in the fight of Roncesvalles. A wall of stout masonry, not above five feet in height, and supported behind by earthworks, so as to resemble an escarpment, yielded before the weight of water, as a pane of plate-glass would give way at the charge of a locomotive engine. Some twenty yards’ length of it was rent and thrown down. On examining this fragment afterwards, I found that the materials of the wall were solid blocks and angular bits of Wenlock limestone, and the cement used of the strongest. I believe, however, if it had been three times as strong a barrier, those waves would have levelled it.

I subsequently witnessed in that very neighbourhood a yet more furious tempest of wind, but had no opportunity of measuring its effects.