Shifting Winds: A Tough Yarn

by R. M. Ballantyne

One of the great errors which we have been called on, of recent years, to unlearn, is the supposed irregularity and uncertainty of the winds and waves. Nothing is more regular, nothing more certain—not even the rising and setting of the sun himself—than the circulation of the waters and the winds of earth. The apparent irregularity and uncertainty lies in our limited power and range of perception. The laws by which God regulates the winds and waves are as fixed as is the law of gravitation, and every atom of air, every drop of water, moves in its appointed course in strict obedience to those laws, just as surely as the apple, when severed from the bough, obeys the law of gravitation, and falls to the ground.

One grand and important fact has been ascertained, namely, that all the waters of the sea flow from the equator to the poles and back again.

Disturbed equilibrium is the great cause of oceanic currents. Heat and cold are the chief agents in creating this disturbance.

It is obvious that when a portion of water in any vessel sinks, another portion must of necessity flow into the space which it has left, and if the cause which induced the sinking continue, so the flow to fill up will continue, and thus a current will be established.

Heat at the equator warms the sea-water, and makes it light; cold at the poles chills it, and makes it heavy. Hot water, being light, rises; cold water, being heavy, sinks.

Here, then, is a sufficient cause to produce the effect of currents in the sea.

But there are other causes at work. Excessive evaporation at the equator carries off the water of the sea, but leaves the salt behind, thus rendering it denser and heavier; while excessive influx of fresh water at the poles, (from rain and snow and melting ice), renders the sea light;—in addition to which corallines and shell-fish everywhere abstract the lime that is in the sea, by secreting it on their bodies in the form of shells, and thus increase the lightness of those particles of water from which the lime has been abstracted. The other particles of water being generous in their nature, hasten to impart of their lime and salt to those that have little or none.

Here, then, we have perpetual motion rendered absolutely certain, both as to continuance and direction.

But the latter causes which I have named are modifying causes which tend to counteract, or rather to deflect and direct currents in their flow. Besides which, the rotation of the earth, the action of the winds, and the conformation of continents and islands, have a powerful influence on currents, so that some flow at the bottom of ocean, some on the surface, some from east to west or west to east, or aslant in various directions, while, where currents meet there is deflection, modification, or stagnation, but there is no confusion; all goes on with a regularity and harmony which inconceivably excels that of the most complex and beautiful mechanism of man’s constructing, although man cannot perceive this order and harmony by reason of his limited powers.

Now, these are facts, not theories founded on speculation. They have been arrived at by the slow but sure method of induction. Hundreds of thousands of practical men have for many years been observing and recording phenomena of every kind in connexion with the sea. These observations have been gathered together, collated, examined, and deeply studied by philosophers, who have drawn their conclusions therefrom. Ignorance of these facts rendered the navigation of the sea in days of old a matter of uncertainty and great danger. The knowledge of them and of other cognate facts enables man in these days to map out the so-called trackless ocean into districts, and follow its well-known highways with precision and comparative safety.