CHAPTER IV.
Terrestrial phenomena—Footmarks on rocks—The Logan stone—Sounds in stones—The cave of St. Paul—Atmospherical phenomena—Intermitting springs—Waters of magical power.
Terrestrial phenomena—Footmarks on rocks—The Logan stone—Sounds in stones—The cave of St. Paul—Atmospherical phenomena—Intermitting springs—Waters of magical power.
Inproceeding to illustrate the operation of natural laws, we may look now at some of the phenomena connected with the globe we inhabit, of which, where little knowledge is possessed, erroneous and frequently superstitious opinions are still entertained.
Marvellous tales are often told of rocks. There is, for example, a tradition of a nobleman being engaged in the chase, or pursued by his enemies, without being hurt; whose horse left the prints of his feet on a mass of stone, over which he passed. But, unhappily for the tale, other impressions have been observed besides those of the horse’s feet; and it is affirmed by various naturalists, deserving of credit, that they must have been made by very different animals, at a remote period, before the stone had completely hardened. Other instances of the same kind might easily be given. In the British Museum, there is a slab having similar impressions, obviously producedby the same means. It was dug from a great depth; a mass of stone, many feet in thickness, having been formed above the layer which received, in a soft state, the impression from the feet of several animals.
Other impressions, of which we read or hear, are nothing more than tricks of art. Such, most probably, is the impression of the foot of Budda upon the Peak of Adam, at Ceylon; the print of the foot of the idol Gaudama, in the Burmese empire, which has been three times reproduced; and most certainly this is the case with the so-called impressions of the feet of our blessed Lord and Saviour, shown to the present day, on Mount Olivet.
The cave of St. Paul, at Civita Vecchia, the former capital of the island of Malta, is an excavation, about nineteen feet in height, and fifty in circumference; in a soft, white, limestone rock, more friable than chalk. A belief that the stone was endowed with miraculous medical virtues, led people to carry away large quantities of it during the sway of the knights. In 1770, when visited by Brydone, the cave was in the highest celebrity; not only every house in the island had a medical chest of it, but large quantities were sent to different countries in Europe, and even to the East Indies. It was supposed to have a miraculous power which preserved it from diminution; which may be accounted for by a natural law—the calcareous process of formation still going on—while its healing power is to be attributedto its having some of the properties of magnesia; which leads, according to Dr. Walsh, to its still being given as a purgative-sudorific in eruptive or fever complaints.
One instance of gross superstition, as connected with rocks, is too important to be omitted. The trial by ordeal appears to have been very early practised among the Celtic tribes of Europe, who were always under the influence of an artful and domineering priesthood. Thus, it is said that in cases of doubtful accusation the Druids made use of the rocking-stones which were common in Britain, and that the culprit was acquitted or condemned according as he succeeded or failed in shaking them. Mason alludes to this trial in the followinglines:—
“Behold yon hugeAnd unknown sphere of living adamant,Which, poised by magic, rests its central weightOn yonder pointed rock; firm as it seems,Such is its strange and virtuous property,It moves obsequious to the gentlest touchOf him whose heart is pure; but to a traitor,Though e’en a giant’s prowess nerved his arm,It stands as fixed as Snowdon.”
“Behold yon hugeAnd unknown sphere of living adamant,Which, poised by magic, rests its central weightOn yonder pointed rock; firm as it seems,Such is its strange and virtuous property,It moves obsequious to the gentlest touchOf him whose heart is pure; but to a traitor,Though e’en a giant’s prowess nerved his arm,It stands as fixed as Snowdon.”
“Behold yon hugeAnd unknown sphere of living adamant,Which, poised by magic, rests its central weightOn yonder pointed rock; firm as it seems,Such is its strange and virtuous property,It moves obsequious to the gentlest touchOf him whose heart is pure; but to a traitor,Though e’en a giant’s prowess nerved his arm,It stands as fixed as Snowdon.”
“Behold yon huge
And unknown sphere of living adamant,
Which, poised by magic, rests its central weight
On yonder pointed rock; firm as it seems,
Such is its strange and virtuous property,
It moves obsequious to the gentlest touch
Of him whose heart is pure; but to a traitor,
Though e’en a giant’s prowess nerved his arm,
It stands as fixed as Snowdon.”
A little knowledge would have disabused the mind of this delusion. The celebrated Logan or Logging-stone, near the Land’s End in Cornwall, is an immense block, weighing about sixty tons. The surface in contact with the under rock is, however, of very small extent; and the whole mass is so nicely balanced, that, notwithstanding its magnitude, the strength of a single man is sufficient to make it oscillate,when applied to the under edge. It is the nature of granite to disintegrate or decompose by the action of the air and moisture; a huge mass is thus split into several blocks, and at length, by the continued operation of the elements, one is suspended on the rest.
rock balancing on point of a larger rock
Sounds emitted from rocks have often been regarded as portentous. Mr. G. Bennett, when at Macao, had his attention directed to a mass of granite rocks, appearing as if separated by some convulsion of nature, many of which were found, when trodden on, to be movable. The first, and by far the most sonorous, waspartially excavated underneath; and, by striking it upon the upper part, a deep sound, “like that of a church bell,” was produced. “The battered appearance of the stone above,” it is said, “bore several proofs of how many visitors had made this lion roar.” Many of the other rocks were also sonorous, but not so loud as the first, and, from their situations, “they were movable when trodden on; but it could not be seen, whether, like the preceding, they were excavated, and, in consequence of being so, sonorous.”
In the chain of El-Heman, and not far from the Red Sea, is the Jebal Narkous, or “Mountain of the Bell.” It forms one of a ridge of low calcareous hills, which are connected by a sandy plain, extending, with a gentle rise, to their base. It is composed of a light-coloured friable sandstone, about the same as the rest of the chain; but an inclined plane of almost impalpable sand rises at an angle of about forty degrees with the horizon, and is bounded by a semi-circle of rocks, presenting broken, abrupt, and pinnacled forms, and extending to the base of this remarkable hill. Its height is about four hundred feet.
Lieutenant Wellsted observed, that the shape and arrangement of the rocks resembled, in some respects, a whispering-gallery; but he ascertained, by experiment, that their irregular surface rendered them but ill-adapted for the production of an echo. Seated on a rock at the base of the sloping eminence, he directed a Bedouin to ascend; and it was not till he hadreached some distance that the lieutenant perceived the sand in motion, rolling down the hill to the depth of a foot. It did not, however, descend in one continued stream, but, as the Arab scrambled upwards, it spread out laterally and above, until a considerable portion of the surface was in motion. As the sand began to fall, the sounds produced might be compared to the faint strains of an Eolian harp when its strings first catch the breeze. When the sounds became more violently agitated by the increased velocity of the descent, the noise more nearly resembled that produced by drawing the moistened fingers over glass. As it reached the base, the reverberations attained the loudness of distant thunder, causing the rock on which lieutenant Wellsted was seated to vibrate; and the camels, animals not easily frightened, became so alarmed, that their drivers could only retain them with difficulty. The noise, it was remarked, did not issue from every part of the hill alike, the loudest being produced by disturbing the sand on the northern side, about twenty feet from the base, and about ten from the rocks that bound it in that direction. The tradition is, that the bells of a convent were buried here; the Bedouins trace the sounds to several wild and fanciful causes; but, in the experiment now described, it was evident that the sounds sometimes fell quicker on the ear, and at other times were more prolonged, according to the Arab’s increasing or retarding the velocity of his descent.
Dr. Chladni made many curious experiments on the figures assumed by sand and similar substances, when strewed over vibrating sonorous bodies. The reader may easily try an experiment of this kind. Let a square piece of glass be taken, such as that used for windows, not less than four or five inches over, the edges of which are to be smoothed by grinding. Spread over the plate, as evenly as possible, a little sand, and, holding it between the thumb and fore-finger, in the middle, pass the bow of a violin against one of its edges, drawing it either upwards or downwards, in a direction perpendicular to its surface. A tremulous motion will be immediately observed, and the sand will assume some particular and fixed figure. If the bow be passed over the middle of one of the sides, the sand will arrange itself in the direction of the two diagonals, dividing the square into four isosceles triangles. If the bow be applied at any point which is one-fourth the length of the square from any angle, the arrangement of the sand will represent the two diameters of the square, dividing it into four equal figures of the same form. If the square be held at the two extremities of either diameter, and the bow be applied to the extremities of the other diameter, the sand will take the figure of an oval, having its major axis in the same direction as one of the diameters.
Other experiments of the same kind have since been made by M. Voigt, and also by the celebrated Oersted. The latter covered a plateof metal or glass with the lycopodium seed, or the seed of the club-moss, instead of sand; he then tried to produce a sound in the manner of Chladni, and instantly he saw the dust distribute itself into a number of little regular tumuli, which put themselves in motion at their extremities, or formed the figures discovered by this naturalist. They always ranged themselves in the form of a curve, the convexity of which was in proportion to the point touched by the violin bow, or towards the point which has an analogous situation; the nearer that each of these little heaps was to these points, the greater was its height, a circumstance which gave remarkable regularity to the figure. The interior of the small elevations thus obtained, were in constant motion during the continuance of the sound, and the duration of the vibrations might be observed on a plate from four to six inches in diameter. At one moment the height increased, at another it diminished, and the dust had the appearance of arranging itself in small globules, which rolled one above another.
We may now return from these very interesting facts, to others on a far larger scale. Near the Kom-el-Hett’an, or the mound of sandstone, which makes the site of one of the palaces and temples of Amunoph III., are two sitting colossi, which seem to assert the grandeur of ancient Thebes. The easternmost of the two is doubtless the statue reported by ancient authors to utter a sound at the risingof the sun. It was said to resemble the breaking of a metallic ring, or harp-string. The superstition of its Roman visitors ascribed the colossus to Memnon, and a multitude of inscriptions attributed to him miraculous powers. The memory of its daily performance is still retained in the traditional appellation of Salamat, “salutations,” by the modern inhabitants of Thebes. It is said to have “saluted” the emperor Adrian and his queen Sabina twice; but some persons, of course of humble rank, were disappointed on their first visit, and obliged to return another morning to satisfy their curiosity.
And yet there is ample reason to believe that the whole was an artifice of the priests. In the lap of the statue is a stone; and as sir Gardiner Wilkinson discovered, on examining the inscriptions, that one Ballilla had compared the sound the stone emitted, when struck, to the striking of brass, he determined to put the matter to the test. Accordingly, posting some peasants below, and ascending to the lap of the statue, he struck the sonorous block with a small hammer, and inquiring what was heard by the peasants, they answered, “You are striking brass.” “This,” says sir Gardiner, “convinced me that the sound was the sound that deceived the Romans, and led Strabo to observe that it appeared to him as the effect of a slight blow.” “The Theban priests,” he adds, “must have been considerable gainers by the credulity of those who visited theirlion.”
The reader who may have taken the delightful walk from Tunbridge Wells to the High Rocks, and examined particularly those huge masses, will not fail to remember the one called “the Bell Rock.” On entering the space between this one and the next, it may be struck with a stick, when a sound will be heard like that produced, on a large metallic body being smitten.
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 producingthese 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 thanthe 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 bythe 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.
ThePhilosophical Magazinecontains 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 theyhad 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.”
A correspondent of theAthenæum, in a letter, dated Naples, January 3rd, 1847, mentions another very striking phenomenon. He was standing on a cliff overlooking the Mediterranean, accompanied by an Italian friend. The air was perfectly tranquil, and yet in a moment he felt himself grasped and encircled, as it were, by an unseen and irresistible power, and, in spite of his struggles, he felt himself sailing through the air at a balloon speed. After a few moments of his aërial travelling, he was pitched halfway down the cliff into the centre of an empty lime-kiln, not far from the sea. Nor was he alone; there was another heavy fall; for his friend stood opposite him. As they were encircled by a force, equal at all points, though the shock was violent, they fell on their feet, but sank directly to the ground, and there sat gazing at one another, unable either to move or speak. Happily, no bones were broken; but so severe were the internalinjuries experienced, as to confine them to their beds for some time, and they expect the internal effects of their involuntary and dangerous voyage to remain for a considerable time.
As the population of the coasts of the Mediterranean are exceedingly ignorant and superstitious, it is not surprising that the people in the neighbourhood said that the Shal’ombre, the evil spirits, in the lime-kiln, must have drawn the travellers in; and attributed their deliverance to the intercession of the souls in purgatory for the acts of charity they had performed!
To avoid any calamities, which the mariners of Naples generally attribute to demoniacal influence, they resort to the practice of witchcraft. Few are the barks that venture to the coral fishery, or the coasting-trade, without having a magician on board. Persons of this class, however, who practise the art supposed to be required at sea, or who even reveal it to others, cannot receive absolution from an ordinary confessor. It is comprehended under the head of “malaficia,” one of the reserved sins to be found in the printed list of directions appended to every confessional in Italy.
And yet, were witchcraft available in any case, it could not be in connexion with the natural operation, which the mariners call “trombe di mare.” The travellers suffered, in fact, from a strong wind, connected with the phenomenon of a water spout, observed, for the most part, at sea, but sometimes also on shore.Its usual appearance is that of a dense cloud, like a conical pillar, which seems to consist of condensed vapour, and is seen to descend with the apex downwards. When over the sea, there are generally two cones, one projecting from the cloud, the other from the water below it. They sometimes unite, and then a flash of lightning is observed; on other occasions, they disperse before any junction takes place. The effect appears to be, at least partly, electrical; the cones being in opposite states, the positive and negative attraction ensue; and, when union takes place, which is indicated by the flash, the bodies are restored to their equilibrium.
The magicians on the coast practise what they call the art of “cutting” the “trombe.” As soon as it is seen approaching in the direction of a boat, the wizard goes forward, sends all the crew aft, that they may not be eye-witnesses of what he does; and using certain signs or words, and making a movement with his arms as if in the act of cutting, the enemy falls in two, and disappears.
We are reminded by these circumstances of “the news from the country,” which theSpectatordescribes as brought to him by sir Roger de Coverley. One part of it was, that Moll White was dead, and that about a month after one of the baronet’s barns fell down, which led to the shrewd remark: “I do not think the old woman had anything to do with it.” Nor do we think that the wizard of the Mediterranean has anything to do with “cutting thewind.” The probability is, that he seizes on the time for his movements, which, from experience, he knows to precede the dispersion of the cloud, and thus acquires credit to which he has not the slightest claim.
This chapter may appropriately be concluded by a reference to the waters of the earth, which are often represented as endued with a supernatural power. The Ilissus, rising on Mount Hymettus, to the east of Athens, and overflowing its banks, furnishes a supply of excellent water to the monastery of Sergiani. On one side, are three small caverns in the rock, with double entrances; apparently the work of nature, but probably aided by art. They are still supposed, as they have been during past ages, to have a mystic virtue; and “no remedy,” says Dodwell, is considered so efficacious for a sick child as “to drag it two or three times from one cave to another; by which it is either killed or cured. Several ancient wells are observed in the rock on each side of the river. Near these, the foundation of a wall crosses the bed of the Ilissus.”
Springs, in various parts of this and other countries, alternately ebbing and flowing, have been, and are still, in some cases, supposed to be under the ban of witchcraft. And yet the phenomena are easily explained by natural laws. If the shorter end of a bent tube,A, whose branches are of an unequal length, be placed in a basin of water, and the air is drawn from it, we have a syphon, which will decant the waterinto any vessel. Now such tubes as these are naturally formed in the earth, and if the water be drained into a cavity,B, having a syphon-like channel,C, it is evident that it will flow as long as the syphon can act, and it will then cease.
A: bent tube; B: water-filled cavity; C: channel out of cavity
Seneca describes a spring near to Tempe, in Thessaly, the waters of which are fatal to animals, and penetrate iron and copper. Yet, it is probable, as Dr. Thomson states, that “this spring contained either free sulphuric acid, or a highly acidulous salt of that acid. This acid has been detected in a free state, as well as hydrochloric acid, in the water of the Rio Vindagre, which descends from the volcano of Paraiè, in Columbia, South America. Sulphuric acid is also found in the waters of other volcanic regions. The sour springs of Byron, in the Genessee country, about sixty miles south of the Erie canal, contain sulphuric acid.Such waters would rapidly corrode both iron and copper, converting the former into green, the latter into blue vitriol—sulphates of both metals.”E
It would be easy to extend these instances, in connexion with the phenomena of the globe, but the present will suffice to show that a little knowledge of natural science is an antidote to many superstitions. We proceed now to illustrations of agencies in active operation of a different character.