LITMIR.BIZ

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to denote contempt.

      I begged pardon for interrupting him, and he went on:—

      ​"There can be no doubt that we have solved the problem of life below the water, and whether this be a return to the habits of a remote ancestor, or a totally new faculty we have acquired, is of much less importance than the fact itself.

      "It is believed that the first great requisite for our subaqueous life was the invention of a corrective of that defect of vision produced by the contact of the eye with the water. The cause of this defective vision is the optical structure of the eye itself, the refractive power of whose humours differs but slightly from that of water; consequently, when it is immersed in water, the rays of light are not deflected sufficiently to allow the images of external objects, to be accurately focussed on the retina; hence only a very imperfect vision is possible for the unaided eye below the water.

      "Our opticians discovered that perfect vision could be restored under water by means of a lens of considerable power. Spectacles were constructed with such lenses, and the first step was made towards rendering life below water practicable.

      "At first, we, like yourselves, constructed our lenses of solid glass; but as the refractive power of glass is not very much greater than that of water, there was an enormous difference between the power of a lens used in air and in water. Hence our opticians early adopted the plan of making lenses of all descriptions for use below water, of air. Air being the less refractive medium, our air lenses are of precisely the opposite shape to that of your glass lenses. Our ordinary method of making these air lenses is to have sections of thin glass globes of certain diameters fixed in a ring of metal or bone, with their concavities looking outwards. They thus enclose a concave ​lens-shaped portion of air, which effects the required refraction. In the better kind of lenses the two surfaces of the glass are ground so that both shall be of exactly the same radius of curvature.

      "All the lenses of our optical instruments for subaqueous use, microscopes, telescopes, &c., are made in this way. For spectacles these lenses are especially convenient, for while they are lenses of the required power under water, they have no refractive power in air, and consequently may be worn both in and out of the water; in the former case causing, in the latter not preventing, perfect vision.

      "The next question that seems to have occupied the attention of the pioneers of our submarine life was that of obtaining the needful supply of air below the water; for it was extremely awkward, and indeed quite fatal to anything like residence under the water, to be obliged to come to the surface every minute or so, to get a chestful of air.

      "This difficulty was overcome by the distribution of air-pipes throughout the area occupied.

      "At first, as you may imagine, this was done on a very small scale. It was originally not expected that it would ever be possible to remain permanently below the water, but only for a few hours during the extreme heat of the day.

      "But as time went on, the ingenuity of our engineers and mechanicians who kept themselves well posted in all the improvements in their arts that were made in Europe—for works on mechanical science formed a considerable proportion of the books rescued from the wrecks that were more frequent formerly than now,—overcame all difficulties; and as the area of inhabited space yearly extended, the net-work of air-pipes gradually spread over every portion of the vast inland sea ​enclosed by our coral reefs, which includes many hundreds of square miles.

      "At the same time the air-supply through these pipes was so improved that the air in the pipes, by mechanical contrivances, was kept at a considerable pressure; and by means of valves and stopcocks, the act of breathing below water is performed as easily as in the atmosphere; and there is no need to come to the surface at all for purposes of respiration. The breathing apparatus is so constructed that every mouthpiece is connected with two sets of tubes, one of which receives and carries off the expired air, whilst the other supplies the fresh air to be breathed. In this way the awkward and unsightly gurgling of the expired air is prevented.

      "The quality of the air for breathing has also been much improved by the admixture of a considerable proportion of oxygen with the air supplied, so that one respiration of this oxygenated air is only required where many respirations of non-oxygenated air would be needed.

      "Thus you will find that it is not necessary to breathe oftener than once in four or five minutes when you are used to this mode of breathing.

      "When we make excursions beyond the reef into the ocean we carry with us metal bottles of condensed oxygenated air, whereby we are enabled to remain many hours away from the air-pipes of the enclosed sea without inconvenience."

      After this explanation, my Instructor proposed that I should accompany him on a short excursion below the water, in order that I might learn practically something of the mode of life and qualify myself for citizenship in this singular community.

      So having taken off my clothes, I donned the ​costume which is de rigueur in the water, namely a pair of spectacles, bathing-drawers and weight-belt.

      This last piece of dress is worn for the purpose of counteracting that tendency to rise to the surface of the water which the smaller specific gravity of our bodies produces. It is a broad belt with pieces of lead or other heavy metal let into it. In order to provide me with a weight-belt precisely adapted to my requirements, my Instructor first ascertained my specific gravity by means of a simple apparatus, he then calculated the cubic contents of my body, and finally referred to a printed table to determine the weight of the belt I would require. Having found this, he took from the cupboard, where a number of these belts were kept, one of the precise weight required by me with which I at once girded myself.

      I should add that these belts are provided with india-rubber cells which can be inflated at pleasure by the wearer so as to counteract the weight of the pieces of lead, and so restore the buoyancy of the body. This inflation is resorted to when the wearer wishes to bring his head above the surface of the water.

      We sallied forth from the coral grotto and walked down the sloping beach of snow-white sand which the fierce rays of the sun had made uncomfortably warm for the naked feet.

      The clear blue water felt deliciously cool, coming out of the sultry air, though I was told that its temperature was not much below eighty degrees.

      Diving down into the pellucid depths, I marvelled at the extreme beauty of the scene. Corals of the most exquisite shape and colour, branching out into every variety of fantastic and elegant form; here, like the branches of trees as we see them in winter silvered ​over with hoar-frost; there, in great fan-shaped masses, white, red, purple and violet, large round madrepores, sponges of all shapes and sizes, and beautiful seaweeds of the brightest hues and most exquisite foliage, Shoals of brilliantly coloured fishes, bright scarlet, blue and orange, or party-coloured with alternate black and yellow or black and scarlet bands, darted hither and thither among the corals and sea-weeds, or hung motionless in the water above and around us.

      I had hardly time to observe all this when I felt the need of air. My conductor placed a pipe to my lips and signed to me to breathe. My first attempt was not very successful, and I felt as if I must go to the surface. But my companion, seeing my embarrassment, produced a small spring clamp which he fastened on my nostrils so as effectually to stop them. I was then able to take a full inspiration, which at once restored me to my self-possession; and after two or three attempts, I found I could use the apparatus with tolerable facility.

      I noticed that my Instructor possessed the power of keeping his nostrils tightly closed by their own muscular action; and he told me that all his countrymen had the same power. Indeed, it was absolutely necessary to close the nostrils under water, not only for the purpose of using the breathing tubes, but also to prevent the water penetrating into and filling up the cavity of the nose. I had to use the nose-clamp for some time but I ultimately, by repeated exercise, acquired the power of closing my nostrils voluntarily. But this is a digression.

      I found that my weight-belt completely counteracted the tendency of my body to ascend to the surface, and so true was the equilibrium established between my ​body and the water, that I could assume any position, rise, descend or remain stationary in the water, without any conscious effort;

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