having come into focus, and his scalp being perilled by this touch of solar pleasantry.

And since without light there can be no colour, it has been observed that the hues of animals, which dwell at various depths in the ocean, decline in intensity until a certain limit is reached; and if, beyond that point, life still exists, it appears to be as pallid and cadaverous as if it were already on the brink of death. The late Professor Edward Forbes established a kind of chromatic scale amongst the Testacea of the Egean Sea. Ranking them in zones according to their different habitats, he found that the liveliest tints and gayest combinations of colour were to be discovered in the shells which occupied the uppermost, or littoral, belt. Whilst the species near the surface were drenched in prismatic glories, the denizens of the inferior regions grew more modest in their markings and adornments, until at last even the faint flush of colour discernible amongst these creatures seemed to be well-nigh extinguished, and the few specimens which survived were, for the most part, wan and lustreless things. Out of 18 shells raised from a depth of 100 fathoms and upwards in the Mediterranean, only one presented any decided tintings; and, in our own seas, every individual drawn from a similar depth proved to be wholly without hue.

Further and further we continue to sink. The time we have consumed, and let us be frank-the trepidation we have endured, might almost induce us to believe that we had descended some thousands of feet into the watery abyss. And yet a few fathoms will measure the whole distance we have described. Since the height, and consequently the weight of the fluid above us is increasing at every step of our progress, it follows that the space reserved for air within the bell is constantly contracting. You observe that the liquid is gradually rising in the machine. You have had to double up your legs already, I perceive; and if we proceed much deeper we shall be immersed to our chests, and almost strangled in the embrace of the floods. For, at a depth of about thirty-two feet, we are exposed to a pressure equivalent to that of a double atmosphere. In other words, an additional weight of from fourteen to fifteen pounds is put upon every one of our square inches. The same invisible sprite who amuses himself by poking invisible quills into your ears has been silently piling up several hundredweights upon our frames, so that each of us now sustains a burden of more than twenty tons. "What Atlases we must be !" you exclaim. Fortunately there is no vacuum within the body, otherwise it would collapse and shrivel beneath the prodigious incubus. If a diving-apparatus were a closed machine, it might be lowered to a greater depth than an open bell; but it would be necessary to construct it of stout materials in order that it might resist the powerful strain to which it would be exposed. Sir John Herschel mentions an individual (probably Mr. Day) who fitted up a vessel for recovering treasure from sunken ships, and who went down by way of trial, but never returned to the light; for, as no adequate allowance had been made for the increased pressure of water, the frail fabric was crushed

like a band-box in the coils of a boa-constrictor. Or, to put the matter in a more pleasing form, let me recommend you to take a bottle of pure sherry (if such a phenomenon can be discovered in Europe), and, having corked and sealed it, send it into the depths of the ocean by means of a sounding line. Haul it up, and take a glass-I beg to decline for myself—and what will be the result? Why, you will find that a vertical voyage does not improve the quality of wine as a horizontal one is presumed to do. The liquid which went down price six or seven shillings the bottle will come up at considerably less than a farthing the barrel. The superincumbent weight of the ocean has, in fact, so compressed the cork that the contents will be little better than mere brine. Need I say, therefore, that no merman accustomed to sport in deep waters could ever wear such a head-dress as a terrestrial hat, for it would be forced down upon his skull like an empty eggshell; and certainly no sea-nymph would dream of employing garments stiffened by crinoline or expanded by slender steel hoops, like their sisterhood of the land.

But here you remind me that a curious question is sometimes raised -occasionally, too, amongst very intelligent people-respecting the effect of deep water upon sinking substances.

What excellent nerves you must have to propound a philosophical thesis at this depth below the surface! Such composure of mind is exceedingly uncommon in a diving-bell. I will endeavour to wind up my courage to the height of your argument. Now, what is your difficulty?

This it has sometimes been contended that as the weight of water constantly increases there must be a point, if the sea be deep enough, where electric cables will float, and where even cannon-balls must refuse to sink any further. This conclusion, however, arises from some confusion of idea in regard to pressure and compressibility. If water were a "squeezable" fluid, like the air in the bell, a given quantity taken from the surface of the ocean-say, a pailful-would be gradually reduced in bulk the lower we descended, until it might be contained in a common tumbler. But in that case its density-that is, the quantity of matter included in a determinate space-would be proportionately augmented. Now, the only condition on which a culic inch of iron or other heavy substance could remain in suspension at any particular depth, would be that it weighed neither more nor less than a cubic inch of the surrounding fluid. But it so happens that water is virtually an incompressible liquid. Its particles won't consent to be forced into closer proximity. The Florentine academicians thought they could subdue its stubbornness by subjecting a sphere of gold filled with the fluid to enormous pressure; but the drops oozeł through the metal rather than compromise their character by the slightest concession. Subsequent experiments by Canton, Perkins, and Oersted have indeed shown that there is some small contraction ia bulk; but it is so trifling that the last-named philosopher estir tel it at one part in forty-six millions for each additional atmospher

Since, therefore, at a depth of thirty-two feet, a cubic inch of water will have yielded to this extent only, we may consider that for all practical purposes the liquid is incapable of condensation.

On the other hand, if a body when carried down into deep water admits of reduction from the pressure of the fluid, or if its structure is so porous that the liquid can be readily forced into the interior, its gravity will be considerably, and (it may be) grotesquely increased. A piece of wood once carried to the floor of the Atlantic would lie there like a piece of metal. Scoresby tells us of a boat which was dragged down by a wounded whale, and which required five-and-twenty men to raise it to the surface. It was found to be so heavy in consequence of the injection of water into its tissues that two other boats -one at each extremity-were necessary simply to support it; and splinters flung into the ocean sank as if they were strips of iron.

But here our discourse is interrupted by a slight shock. I don't like it at all. My nerves unfortunately are not in the best possible order for such an excursion, but I trust I am not going to be seriously frightened. You, too, begin to feel strongly impressed with the solemnities of our position. Quite reasonable that you should! If Dr. Johnson refused to envy the man who could stand unmoved at Marathon or Iona, we may decline to be the individuals who could sit phlegmatically in the sea, and not experience an emotion of awe when we thought of the great abyss of waters in which we were immersed. Sir, we ought not to come down here like brute beasts. A little faltering in the voice, a little fluttering at the heart, a little perspiration on the brow, are but fitting expressions of homage to the majesty of the ocean.

The cause of the shock, however, is soon explained. The bell has grazed the side of a sunken rock, and, after a few concussions (which induce us to feel still more like the man at Marathon or Iona), it alights on the bed of the sea. Fortunately we have made our descent in a shallowish quarter. All divers are not equally happy in their landing, if it may be so termed. Triewald refers to one who came into contact with the bolt of a wreck, which pierced a hole in the side of his machine. The water began to rush in, the air began to rush out; and the big bubbles, gurgling to the surface, threw the attendants into great consternation. With remarkable presence of mind, however, the diver thrust his arm into the aperture, and, having given the signal, was drawn up in safety, thanks to this extemporaneous plug.

Once down at the bottom of the ocean, the diver may leave the bell if he is provided with aquatic armour, of which various kinds have been devised. These mainly consist of a stout helmet for the head, and of strong sheathing for the upper part of the frame, or else the person is protected by a sort of case from which the arms protrude for the purpose of gathering the treasures which somehow or other most people expect to find at the bottom of the sea. To supply the explorer with air a flexible tube is connected with the bell, or a sufficient allowance of breathing material is forced into a belt by means of a condensing pump. Thus equipped, I fancy that any sea-deity who may chance to fall in with one of these human monsters-foraging for

like a band-box in the coils of a boa-constrictor. Or, to put the matter in a more pleasing form, let me recommend you to take a bota of pure sherry (if such a phenomenon can be discovered in Eur ;and, having corked and sealed it, send it into the depths of the a by means of a sounding line. Haul it up, and take a glass-I be 2 to decline for myself—and what will be the result? Why, you will £1 that a vertical voyage does not improve the quality of wine as a hizontal one is presumed to do. The liquid which went down price x or seven shillings the bottle will come up at considerably less than a farthing the barrel. The superincumbent weight of the ocean has, ra fact, so compressed the cork that the contents will be little better than mere brine. Need I say, therefore, that no merinan accustomed tɔ sport in deep waters could ever wear such a head-dress as a terrestrial hat, for it would be forced down upon his skull like an empty 25shell; and certainly no sea-nymph would dream of employing garments stiffened by crinoline or expanded by slender steel hoops, like ther sisterhood of the land.

But here you remind me that a curious question is sometimes raised -occasionally, too, amongst very intelligent people-respecting the effect of deep water upon sinking substances.

What excellent nerves you must have to propound a philosophal thesis at this depth below the surface! Such composure of min. 1 exceedingly uncommon in a diving-bell. I will endeavour to wind up my courage to the height of your argument. Now, what is your difficulty?

This it has sometimes been contended that as the weight of water constantly increases there must be a point, if the sea be deep en where electric cables will float, and where even cannon-bills r refuse to sink any further. This conclusion, however, a ses fr m some confusion of idea in regard to pressure and compressibility. water were a "squeezable" fluid, like the air in the bill, quantity taken from the surface of the ocean-say, a pailtul-w be gradually reduced in bulk the lower we descended, until it mig the contained in a common tumbler. But in that case its density—tha N the quantity of matter included in a determinate space-would be proportionately augmented. Now, the only condition on wi ha inch of iron or other heavy substance could remain in susper, a any particular depth, would be that it weighed neither men ra than a cubic inch of the surrounding fluid. But it so hopens to t water is virtually an incompressible liquid. Its particles won tonå to be forced into closer proximity. The Florentine aad nämä thought they could subdue its stubbornness by subjecting a sp gold filled with the fluid to enormous pressure; but the dr through the metal rather than compromise their cara trty t slightest concession. Subsequent experiments by Canton, PAMI Oersted have indeed shown that there is some small contract. a bulk; but it is so trifling that the last-named philoso; her estin it at one part in forty-six millions for each ad litional atte; b.

Since, therefore, at a depth of thirty-two feet, a cubic inch of water will have yielded to this extent only, we may consider that for all practical purposes the liquid is incapable of condensation.

On the other hand, if a body when carried down into deep water admits of reduction from the pressure of the fluid, or if its structure is so porous that the liquid can be readily forced into the interior, its gravity will be considerably, and (it may be) grotesquely increased. A piece of wood once carried to the floor of the Atlantic would lie there like a piece of metal. Scoresby tells us of a boat which was dragged down by a wounded whale, and which required five-and-twenty men to raise it to the surface. It was found to be so heavy in consequence of the injection of water into its tissues that two other boats -one at each extremity-were necessary simply to support it; and splinters flung into the ocean sank as if they were strips of iron.

But here our discourse is interrupted by a slight shock. I don't like it at all. My nerves unfortunately are not in the best possible order for such an excursion, but I trust I am not going to be seriously frightened. You, too, begin to feel strongly impressed with the solemnities of our position. Quite reasonable that you should! If Dr. Johnson refused to envy the man who could stand unmoved at Marathon or Iona, we may decline to be the individuals who could sit phlegmatically in the sea, and not experience an emotion of awe when we thought of the great abyss of waters in which we were immersed. Sir, we ought not to come down here like brute beasts. A little faltering in the voice, a little fluttering at the heart, a little perspiration on the brow, are but fitting expressions of homage to the majesty of the ocean.

The cause of the shock, however, is soon explained. The bell has grazed the side of a sunken rock, and, after a few concussions (which induce us to feel still more like the man at Marathon or Iona), it alights on the bed of the sea. Fortunately we have made our descent in a shallowish quarter. All divers are not equally happy in their landing, if it may be so termed. Triewald refers to one who came into contact with the bolt of a wreck, which pierced a hole in the side of his machine. The water began to rush in, the air began to rush out; and the big bubbles, gurgling to the surface, threw the attendants into great consternation. With remarkable presence of mind, however, the diver thrust his arm into the aperture, and, having given the signal, was drawn up in safety, thanks to this extemporaneous plug.

Once down at the bottom of the ocean, the diver may leave the bell if he is provided with aquatic armour, of which various kinds have been devised. These mainly consist of a stout helmet for the head, and of strong sheathing for the upper part of the frame, or else the person is protected by a sort of case from which the arms protrude for the purpose of gathering the treasures which somehow or other most people expect to find at the bottom of the sea. To supply the explorer with air a flexible tube is connected with the bell, or a sufficient allowance of breathing material is forced into a belt by means of a condensing pump. Thus equipped, I fancy that any sea-deity who may chance to fall in with one of these human monsters-foraging for