Locrine”—the river-born Sabrina. The most matter-of-fact man has, when lounging by the shore, been sometimes attacked with the strong desire, if not to people the subaqueous realms of lake or sea with imaginary beings, at least to penetrate the shrouding veil of water, and to discover what are the beauties and what the forms he feels lie hidden beneath the wave. Some men there are, indeed, in whom this wish has grown to be a passion. It is not long since two widely-known and enthusiastic naturalists, possessed with this strong desire to know, prepared the necessary apparatus, and at some risk of life invaded the sea-god’s dominions. Thence they have sent up to us an eye-witness’ report of submarine manners and customs, and told us how the world goes on at the fifty-fathom line. Many a busy dredge, too, has been scraping for years past at the sea-floor, wherever it can be reached, bringing ever new facts before quick eyes and thoughtful brains; till in these times we begin to get a tolerably intimate knowledge of the complicated economies of the water-world; at least in such depths as our researches can be made with ordinary appliances.
Lately, one of the most eminent of English scientific men (now, alas! no more), has attempted to map out the minuter features of these regions, so far as animal life is concerned, with considerable accuracy. The physical geography (if we may so call it) of European sea-bottoms is now a science in which so many facts have been registered, and so many observations made, that practically the waters of our bays and firths have been rolled back for us, and the treasures they cover laid bare to our view. But of those profounder depths, far out in what sailors call “blue water,” neither poet or naturalist have as yet much news to tell us. Here the diving-dress and dredge are alike useless, and even the sounding-line long failed to fathom these tremendous abysses, much less to bring up thence any reliable evidence of their formation or inhabitants. The art of deep sea-sounding—which many, we believe, consider to be merely a thing of every-day life at sea, a simple matter of a string and a lead—is of decidedly recent origin. Human science and ingenuity, which had gauged the heavens and measured our earth’s distance from remotest visible planets; which had sounded abyss after abyss of firmamental space, and brought one faint nebula after another within resolvable distance; stood baffled in the effort to tell the depth of mid-ocean. Many were the trials made to sound in deep water, which all proved failures. The old-fashioned “lead” sunk and sunk endlessly, and sent up no shock to tell when the bottom had been reached: currents which seized the sinking line, dragged it out by thousands of fathoms, and would do so till every reel was emptied. Ingenuity was almost exhausted in new methods. Charges of gunpowder were exploded beneath the waves in the hope that the echo from the sea-floor would reach the surface. Experiment would furnish data for determining the rate at which sound travels in water, and the depth was to be ascertained by computation from the time occupied by the passage of such sound, caused by the explosion, to the bottom and back again to upper air. The theory was pretty; but, alas for fact! in the stillness of the calmest night no reverberation ever reached the listeners. Instruments were made in which a column of atmospheric air should register the aqueous pressure it sustained below, and thus (again by calculation) give the required information; but, pressed upon by such a volume of liquid, nothing could be made sufficiently strong to bear the strain, and so this, too, failed. Sinkers, with screw-propellers attached, were tried, in which the screw made a certain number of revolutions for every fathom of its descent, but it would not do. Electro-magnetism was pressed into the service (what errand under the sun has not electrical agency been set to do?), but without avail: the “blue water” mocked at every effort to gauge it.
At length, after innumerable discomfitures, a simple suggestion led the way to a solution of the difficulty. In all attempts hitherto made to sound with an ordinary “lead” the shock produced by contact with the ground was relied upon for an indication of the depth; in practice it was found that no such shock was ever communicated, but that the line would continue running out endlessly without giving the slightest hint of bottom. Casts made upon this theory gave the astounding depths of thirty, forty, and fifty thousand fathoms, mile after mile of line being swallowed up by the currents. The proposal which paved the way to success was this. To time the hundred fathom marks upon the sounding line as they left the reel, and by using always a line of the same make, and sinker of the same size and weight, to endeavour to establish some law of descent. It was tried, and within a very short time succeeded. The mean of many experiments gave a certain period for the sinking of the first hundred fathoms, another greater period for the second hundred, and so on up to thousands. Now, until the lead has reached the bottom, it will drag out the line at a constantly decreasing but ascertained speed; once there, however, the currents begin to act upon the twine now no longer kept tense by weight; this is the moment at which the true sounding has been accomplished, and its arrival will be very evidently marked by a change in the rate at which the twisted hemp descends; for the force of the currents being of constant intensity will produce an uniform instead of a variable motion, and the fathom-marks will pass more slowly and at equal intervals over the reels. After a few trials this plan was found to give results which might be considered reliable; soundings on being many times repeated over the same spot checking each other with surprising accuracy. The main part of the problem was solved, but there was yet much to be done: though the heavy shot would drag the line to the bottom, it could not afterwards prevent its being drifted perhaps hundreds of fathoms from the perpendicular, and to lift the sinker again to the surface was a complete impossibility; thus though ground was reached and its distance from the surface measured, its nature and peculiarities remained unknown as before. This difficulty also was conquered in the end as our three little slides will testify. A midshipman of the