Magic, Pretended Miracles, and Remarkable Natural Phenomena

by Anonymous

In the road cut by Napoleon between Savoy and France, and about two miles from Les Echelles, there is a gallery twenty-seven feet high and broad, and nine hundred and sixty feet in length, formed in the solid rock. When this road was nearly complete, and the excavations commenced at each end almost met, the partition was broken through by a pick-axe, and a loud and deep sound was heard. We are indebted to Mr. Bakewell for the following solution of this phenomenon. The mountain rises full one thousand feet above the passage, and fifteen hundred above the valley. The air, on the eastern side of the mountain, is sheltered both on the south and west from the sun’s rays; and consequently must be much colder than on the western side. The mountain, therefore, formed a partition between the hot air of the valley, and the cold air of the ravines on the eastern side. When the opening was made, the cold, and therefore denser air, rushed into that rarefied by heat, and a loud report was produced, in the same manner as when a bladder, placed over an exhausted air-pump receiver, is burst.

Baron Humboldt informs us, on credible authority, that subterranean sounds, resembling the tones of an organ, are heard on the banks of the Oroonoko. He supposes that they arise from a difference of temperature between the external atmosphere and the air confined in the crevices of the adjacent granitic rocks. He concludes that, as the temperature of the confined air is greatly increased during the day from the conduction of heat by the rocks; and as the difference of temperature between it and the atmosphere will reach its maximum about sunrise, the sounds are produced by the escaping current.

The following illustrative experiment is not a little curious:—If a tube formed of some elastic and sonorous substance be taken, and a jet of inflamed hydrogen be introduced, a musical sound will be heard. This will take place in a tube closed at one end, if it be large enough to admit a sufficient quantity of atmospheric air to support the combustion of the gas; but if the tube be open at both extremities, the musical sound will be clear and full. Various conclusions have been arrived at in reference to this phenomenon; but they have been set aside by the experiments of Mr. Faraday, who attributes the sounds produced by flames in tubes to a continual series of detonations or explosions.

The first philosopher who exhibited the longitudinal vibration of solids was Dr. Chladni. According to him, the best method of producing these vibrations in rods, is by rubbing them, in the direction of their length, with some soft substance, covered with powdered resin, or by the finger. When glass tubes are employed, they should be rubbed with a piece of rag spread over with fine sand, the tube being held by one of the ends.

“In all longitudinal vibrations,” says the same writer, “the tones depend merely on the length of the sonorous body, and on the quality of the substance, the thickness and form being of no consideration; yet the tones are not varied by the specific gravity of the vibrating substance; for fir-wood, glass, and iron, give almost the same tone as brass, oak, and the shanks of tobacco-pipes.” He also mentions several kinds of longitudinal vibration; in one, to use his own words, “there is a certain point in the middle at which the vibration of each half-stops; in the next there are two, each at the distance of a fourth part from the end; and, in the following, there are three, or more. The tones correspond with the natural series of the numbers 1, 2, 3, 4, etc. If a rod be fastened at one end, during the first kind of longitudinal vibration, the alternate expansion and contraction of the whole rod will take place in such a manner, that they stop at the fixed end; in the next tone there is a resting-point at the distance of one-third from the free end; and in the following there are two. The tones correspond with the numbers 1, 3, 5, 7, and the first of these tones is an octave lower than the first tone of the same rod when perfectly free.”

When examining the nature of sonorous bodies, Dr. Chladni imagined the possibility of producing musical sounds by rubbing glass tubes longitudinally. It, however, became a difficult question to determine in what way an instrument of this kind should be constructed. After much and long-continued unsuccessful thought, he returned home one evening exhausted with walking, and he had scarcely closed his eyes to fall asleep in his chair, when the arrangement he had so long been seeking, occurred to his mind. He soon after completed an instrument, which in every respect answered his expectations.

The euphone, signifying an instrument having a pleasant sound, consists of forty-one fixed and parallel cylinders of glass, equal in length and thickness. In its external appearance it resembles a small writing-desk, which, when opened, presents a series of glass tubes about sixteen inches long, and the thickness of a quill. They are fixed in a perpendicular sounding-board, at the back of the instrument. When used, the tubes are wetted with a sponge, and stroked in the direction of their length with wet fingers; the intensity of the tone being varied by greater or less pressure.

The singular phenomenon of sound occasioned by the vibration of soft iron, produced by a galvanic current, was recently discovered by Mr. Sage, and has been since verified by the observations of a French philosopher, M. Marian. The experiments were made on a bar of iron, which was fixed at the middle, in a horizontal position, each half being inclosed in a large glass tube. By appropriate arrangements, the galvanic circle was completed; and the longitudinal sound could be distinguished, although it was feeble. The origin of the sound has therefore been ascribed to a vibration in the interior of the iron bar; and to the same cause are probably attributable many phenomena.

We now pass on to the violent agitation of the air, which is often productive of surprising results. A quantity of feathers, for example, was scattered one day over the market-place of Yarmouth, to the great astonishment of a large number of persons assembled there. But what was the cause? The timid considered that the phenomenon predicted some great calamity; the inquisitive indulged in a thousand conjectures; and the curious in natural history sagely accounted for it by a gale of wind in the north, blowing wild-fowl feathers from the island of St. Paul’s! Yet, not one of them was right. No guess would explain the cause, and yet it arose from the prank of a frolicsome boy. Astley, afterwards well known as sir Astley Cooper, had taken two of his mother’s pillows to the top of the church, and when he had climbed as far as he could up the steeple, he ripped them open, and scattered their contents to the wind.

The Philosophical Magazine contains an account of a singular snow phenomenon that occurred in Orkney. The paper was contributed by Mr. Clouston, of Stromness. “One night a heavy fall of snow took place, which covered the plain to a depth of several inches. ‘Upon this pure carpet,’ says the writer, ‘there rested next morning thousands of large masses of snow, which contrasted strangely with its smooth surface.’ These occurred generally in patches, from one acre to a hundred in extent, while clusters were often half-a-mile asunder. The fields so covered looked as if they had been scattered over with cart-loads of manure, and the latter covered with snow; but, on examination, the masses were all found to be cylindrical, like hollow fluted rollers, or ladies’ swan-down muffs, bearing a strong resemblance to the latter. The largest measured 3½ feet long, and 7 feet in circumference. The centres were nearly but not quite hollow; and by placing the head within when the sun was bright, the concentric structure of the cylinder was apparent. They did not occur in any of the adjoining parishes, and were limited to a space of about five miles. The first idea, as to the origin of these bodies, was, that they had fallen from the clouds, and portended some direful calamity. But, had they fallen from the atmosphere, their symmetry and loose texture must have been destroyed. The writer having examined them, was soon convinced that they had been formed by the wind rolling up the snow as boys form snow-balls. Their round form, concentric structure, fluted surface, and position with respect to the weather side of eminences, proved this; and it was also evident, from the fact of their lying lengthways, with their sides to the wind; and sometimes their tracks were visible in the snow for twenty or thirty yards in the windward direction, whence they had evidently gathered up their concentric layers.”