THE DEPTH OF THE MEDITERRANEAN.

SOUNDINGS have not yet been made in the Mediterranean by the improved methods lately adopted in the Atlantic, and conducted so systematically by Lieutenant Maury, in some parts of that ocean. But they suffice to indicate depths equal to the average height of the mountains girding round this great basin; and, if one particular experiment may be credited, reaching even to 15,000 feet; an equivalent to the elevation of the highest Alps. This sounding was made about ninety miles east of Malta. Between Cyprus and Egypt 6000 feet of line had been let down without reaching the bottom. Other deep soundings have been made in other places with similar results. We have not yet obtained any official account of the soundings very recently effected by the Tartarus in the lines of sea between Egypt and the Archipelago; but it is stated, on apparently good authority, that one sounding between Alexandria and Rhodes reached bottom at the depth of 9900 feet; another between Alexandria and Candia, gave a depth of 300 feet beyond this. These single soundings, indeed, whether of ocean or sea, are always open to the certainty that greater as well as lesser depths must exist, to which no line has ever been sunk-a case coming under that general law of Probabilities so largely applicable in every part of physics. In the Mediterranean especially, which has so many aspects of a sunken basin, there may be abysses of depth here and there which no plummet is ever destined to reach.-Edinburgh Review.

THE ATLANTIC TELEGRAPH PLATEAU.

THE Ocean bed of the North Atlantic is a curious study; in some parts furrowed by currents, in others presenting banks, the accumulations perhaps of the débris of these ocean rivers during countless ages. To the west, the Gulf-Stream pours along in a bed from one mile to a mile and a half in depth. To the east of this, and south of the Great Banks, is a basin, eight or ten degrees square, where the bottom attains a greater depression than perhaps the highest peaks of the Andes or Himalaya,-six miles of line have failed to reach the bottom; but of this more presently. Taking a profile of the Atlantic basin in our own latitude, we find a far greater depression than any mountain elevation on our own continent. Four or five Alleghanies would have to be piled on each other, and on them added Fremont's peak, before their point would show itself above the surface. Between the Azores and the mouth of the Tagus, this decreases to about three miles. Further north, there is an apparent decrease of depth, with increasing regularity of bottom, though it is problematical whether this is not owing to the greater accuracy with which these observations have been conducted. This appears to be the natural route for the Transatlantic telegraph. Other plans have been proposed-one a northing circuit, between the several points of Scotland, Iceland, Greenland, and the Labrador coast, each span being some 500 miles, or to use one or two of the island groups of the Atlantic. In the route selected we have many advantagesconvenient harbours at either terminus; a depth of water at every

point sufficient to place the wire beyond the reach of any surface causes, such as ice or the anchor of any ship, yet not at an impracticable depth, being at the shoalest several hundred feet, and in midAtlantic not materially over two miles. During a thousand miles of its course, the gradual depression of the ocean bed does not exceed 500 fathoms. On either side lie Ireland and Newfoundland, the breast-works of either continent, approaching within 1700 miles, and forming the natural terminus of its route. Trinity Bay is its western head, and Valentia Bay, on the south-western point of Ireland, its eastern. Specimens of the bottom, when subjected to a powerful glass, exhibit delicate shells and infusoria, fragile as if carved in eggshell, and yet as perfect in all their delicate formation as any of the more durable works of Nature. The least attrition would crumble all this to powder. The inference is, that all agitation of winds and currents is confined to the surface, and that at these sunless depths the great mass of water remains in almost a quiescent state, and that the telegraphic wire, if once laid in safety, would lie for ever beyond the reach of harm, sinking among and covered by these fleecy particles.-New York Times.

HEIGHT OF THE HIMALAYAS.

It appears, from a late survey made of the Himalaya range, by Colonel Waugh, that the Khanchinjinga, which has been hitherto supposed to be the highest summit, is in fact not so-a higher mountain having been discovered, situated between Katamandoo and Khanchinjinga. This last named is 28,156 feet above the level of the sea; but the new summit reaches the enormous height of 29,002 feet. It has been proposed to call this Mount Everest, after a former surveyor-general of India.

REPULSION OF WATER.

DR. BUIST, F.R.S., has communicated to the Royal Society, a paper "On the Causes and Phenomena of the Repulsion of Water from the Feathers of Water-fowl and the Leaves of Plants." When Dr. Buist was residing in Bombay, in the neighbourhood of a number of small tanks or ponds abounding with the lotus or sacred bean of India, and also with four different varieties of water lily, he was struck by the different appearances presented by these when immersed in water, or when water was sprinkled on them. The leaves of the lily, like those of the lotus, floated with considerable buoyancy on the surface, but never, like the lotus, rose above it on a tall independent stem. The leaf of the lily is full of holes about the size of a pin's head, and serrated at the edges. Through these, when the leaf is pressed down, the water perforates freely. The upper surface of the leaf is smooth and shining, and water runs off it as it does off a piece of glass, or greased surface. When placed under the water at an angle of about 45°, the leaf of the lily seems to change colour. The dark purple leaf of the red lily appears of a bright rich pink; and the dark green or bluish-green of the white, pink, and blue lilies, seem to become of a bright emerald-green, the

K

intensity of their hues varying with the angle at which the immersed leaf is seen.

When the lotus leaf is placed under water, it reflects light like a mirror, so that the image of any object, if presented to it at a proper angle, is seen by the spectator as distinctly as if the surface were one of polished metal. When water is thrown on the surface of a floating leaf, it flows off like a pool of quicksilver, reflecting light from the whole of its lower surface. This holds good on all occasions-the repellent property of the leaf exists, however, only on the upper surface.

On examining carefully the cause of this natural phenomenon, Dr. Buist found that the lotus leaf is covered by short microscopic papillæ, which entangle the air and establish a kind of air plate over the entire surface of the leaf, with which in reality the water never comes in contact. Another singular peculiarity connected with the structure of the lotus leaf is the curious respiratory pores which dot its surface. The leaves of the lotus, when full-sized, are from a foot to sixteen inches in diameter. On cutting off a leaf six inches broad, the stem of which was a little less than the third of an inch in diameter, thirty cubic inches of air were collected in an hour, while the vital energies of the plant must have been injured by its mutilation. At this rate, a tank covered by lotus leaves throws off a large proportion of air daily.

Dr. Buist considers that sensible respiration is not at all essential to the repelling power of leaves. The most beautiful manifestation of it that he has met with is in the Pistia, a little floating waterplant, abounding in shallow tanks in India, and much resembling common endive. When pressed under the surface of the water, the leaves present the appearance of molten silver. The same appearance is presented on cabbages, young clover, and a vast variety of other leaves, and it is the cause of the bright pearl lustre of dew. Precisely the same phenomenon is manifested on the wings and backs of divers when they plunge into the water. In this case Dr. Buist conceives that the explanation has been ascribed most erroneously to the existence of grease or oil in feathers; whereas he conceives that it is due to the presence of an air plate repelling the water, so that it never comes in contact with the feathers. The trimming process so carefully performed by water-fowl is probably an application of oil or grease, with the object of separating or dressing the little fibres of the feathers so as to produce an arrangement fitted to entangle the air. The reflection of light from the lower surface of the water is the proof of want of contact, when absolute contact exists even without diffusion or permanent wetting. A piece of polished marble or of glass readily throws off the water without remaining wetted, but no reflection is in this case observable. Dr. Buist throws out a hint to the manufacturers of waterproof cloths, conceiving that they might produce a surface which would entangle and retain a film of air, rendering the substance impervious to water, while, at the same time, the texture would admit the free transmission of respiration or moisture.- Saturday Review, No. 89.

147

Electrical Science.

ELECTRICAL PHENOMENA IN THE UNITED STATES.

THE following paper, by Professor Loomis, has been read to the British Association :

Atmospheric electricity is very abundant in the United States, and often exhibits phenomena more remarkable than are witnessed in most of the countries of Europe, especially in England and Germany. These phenomena are not confined to any particular season of the year; but the exhibitions in summer appear under a different form from those of winter. In summer, free electricity exhibits itself chiefly in the form of lightning during thunderstorms; and these exhibitions are often among the most sublime and impressive phenomena witnessed in any part of the globe. The telegraph wires are exceedingly sensitive to the approach of a thunderstorm. The wires are often charged with electricity from the effects of a storm so distant that no thunder is heard, or lightning seen. I have often stood at such times in a telegraph office, and introduced my own body into the electric circuit, by taking hold of a telegraph wire with one hand, and with the other hand grasping a wire which communicated with the earth. A frequent twinge is felt in the arms, and sometimes through the breast. The shock is pungent and painful, even when scarcely the slightest spark can be obtained by bringing the two wires nearly in contact. Such experiments are unsafe when the electric cloud is near. If, during the passage of a thunder shower, the telegraph apparatus is left in communication with the long telegraph wires, the fine wires of the electro-magnets are almost sure to be melted, and the magnets thereby rendered useless. Sometimes, in telegraphic offices, there occurs an explosion, which melts large wires, and is dangerous to human life. The effect of a feeble current of atmospheric electricity on the telegraph wires is the same as of a current from a galvanic battery. It makes a dot on the telegraph register; and, when a thunderstorm passes in the neighbourhood of a telegraph line, those dots are of constant occurrence, and being interposed between the dots of the telegraph operators, they render the writing confused, and often illegible. The operators are, therefore, commonly compelled to abandon their work when a thunder shower prevails in the vicinity of any part of the line.

The aurora borealis is very common in the United States, even in summer; but, on account of the long-continued twilight, it is seldom witnessed with such brilliancy in summer as in winter. During winter, thunderstorms in the United States are of very rare occurrence, but even at this season they are not entirely unknown. Sometimes in mid-winter, after a series of unusually warm days, a strong wind suddenly springs up from the west, attended by a shower, during which several flashes of lightning, accompanied by

thunder, are noticed. Such a shower is invariably followed by a great and sudden fall of the thermometer.. But, while electrical discharges in the form of lightning are rarely witnessed in winter, other electrical phenomena of great interest are of almost daily occurrence. Those phenomena consist of free electricity residing upon almost all bodies resting on the earth, but sufficiently insulated. This free electricity is particularly noticeable on the clothes and hair of the human body. During the cold months of winter, the human hair is commonly electrical, and especially when it is brushed with a fine comb. Often at such times the fine hairs are seen to stand erect; and the more you comb to make them smooth, the more obstinately they refuse to keep their proper place. If you present your fingers to those electrified hairs, they fly to meet you, like a lock of dry hair attached to the prime conductor of an electric machine. In such cases there is but one remedy: the hair must be thoroughly moistened; after which it lies quietly in its place. During the same season of the year, all woollen articles of clothing become highly charged with free electricity. The pantaloons in particular are found to attract light, floating particles of dust, down, &c., especially near the feet; and it is impossible to cleanse them by brushing. The longer you brush, the more your clothes are covered with dust and lint. Nothing less than a wet sponge is efficient to cleanse them. At night, when you take off your pantaloons, you hear a distinct crackling noise, and, in a dark room, perceive a succession of flashes. You draw your fingers down over them, especially near the lower extremities, and you perceive a repetition of the crackling noise, accompanied by distinct flashes of light. As you take off your flannel drawers, the crackling is again heard, louder than before, and the flashes of light are more vivid. If you take a woollen blanket from your bed, hold it suspended in your left hand, and draw the fingers of your right hand over it, the crackling is equally loud and long continued. Your fingers seem enveloped in a blaze of light, and the flashes can be several times renewed. Brute animals do not escape the general electrical influence. In a cold, frosty night, you draw your hand gently over a cat's back, and you hear a distinct crackling noise, while the cat shows unmistakeable signs of bad temper, and refuses her consent to play the philosopher with you.

Persons riding on horseback during a snow-storm in the night have frequently noticed the extremities of their horse's ears tipped with light, like that of a pale, steady flame. The preceding phenomena are either unknown in summer or are only noticed occasionally, and in an inferior degree; but the aurora borealis is often witnessed in the United States during winter, and frequently attains a splendour such as is surpassed in but few portions of the globe. During the severity of winter, and especially in houses which are furnished with heavy carpets and kept thoroughly warmed, even more remarkable electrical phenomena are often witnessed. If you walk across such a carpet with a slight shuffling motion, and then present your knuckle to some metallic object, as the knob of a door,