MOUNTAIN

MOUNTAIN (Mont), a considerable eminence of land, elevated above the surrounding country: It is commonly full of inequalities, cavities more or less exposed, and strata uncovered. For the natural history of mountains, see MOUNTAIN, GEOLOGY Index.

Attraction of Mountains. This is a late discovery, and a very considerable confirmation of Sir Isaac Newton's theory of universal gravity. According to the Newtonian system, an attractive power is not only exerted between those large masses of matter which constitute the sun and planets, but likewise between all comparatively smaller bodies, and even between the smallest particles of which they are composed. Agreeably to this hypothesis, a heavy body, which ought to gravitate or tend toward the centre of the earth, in a direction perpendicular to its surface, supposing the said surface to be perfectly even and spherical, ought likewise, though in a less degree, to be attracted and tend towards a mountain placed on the earth's surface; so that a plumb line, for instance, of a quadrant, hanging in the neighbourhood of such a mountain, ought to be drawn from a perpendicular situation, in consequence of the attractive power of the quantity of matter of which it is composed acting in a direction different from that exerted by the whole mass of matter in the earth, and with a proportionably inferior degree of force.

Though Sir Isaac Newton had long ago hinted at an experiment of this kind, and had remarked, that "a mountain of an hemispherical figure, three miles high and six broad, would not, by its attraction, draw the plumb line two minutes out of the perpendicular (E.):" yet no attempt to ascertain this matter by actual experiment was made till about the year 1738; when the French academicians, particularly Messrs Bouguer and Condamine, who were sent to Peru to measure a degree under the equator, attempted to discover the attractive power of Chimborazo, a mountain in the province of Quito. According to their observations, which were however made under circumstances by no means favourable to an accurate solution of so nice and difficult a problem, the mountain Chimborazo exerted an attraction equal to eight seconds. Though this experiment was not perhaps sufficient to prove satisfactorily even the reality of an attraction, much less the precise quantity of it; yet it does not appear that any steps had been since taken to repeat it.

Through the munificence of his Britannic majesty, the Royal Society were enabled to undertake the execution of this delicate and important experiment; the astronomer royal was chosen to conduct it. After various inquiries, the mountain Schehallien, situated nearly in the centre of Scotland, was pitched upon as the most proper for the purpose that could be found in this island. The observations were made by taking the meridian zenith distances of different fixed stars, near the zenith, by means of a zenith sector of ten feet radius; first on the south, and afterwards on the north side of the hill, the greatest length of which extended in an east and west direction.

It is evident, that if the mass of matter in the hill exerted any sensible attraction, it would cause the plumb-line of the sector, through which an observer viewed a star in the meridian, to deviate from its perpendicular situation, and would attract it contrariwise at the

Mountains the two stations, thereby doubling the effect. On the south side the plummet would be drawn to the northward, by the attractive power of the hill placed to the northward of it: and on the north side, a contrary and equal deflection of the plumb line would take place in consequence of the attraction of the hill now to the southward of it. The apparent zenith distances of the stars would be affected contrariwise; those being increased at the one station which were diminished at the other: and the correspondent quantities of the deflection of the plumb line would give the observer the sum of the contrary attractions of the hill, acting on the plummet at the two stations; the half of which will of course indicate the attractive power of the hill.

The various operations requisite for this experiment lasted about four months; and from them it appears that the sum of the two contrary attractions of the mountain Schehallien, in the two temporary observations which were successively fixed half way up the hill (where the effect of its attraction would be greatest), was equal to 11".6.—From a rough computation, founded on the known law of gravitation, and on an assumption that the density of the hill is equal to the mean density of the earth, it appears that the attraction of the hill should amount to about the double of this quantity. From thence it was inferred that the density of the hill is only about half the mean density of the earth. It does not appear, however, that the mountain Schehallien has ever been a volcano, or is hollow; as it is extremely solid and dense, and seemingly composed of an entire rock.

The inferences drawn from these experiments may be reduced to the following:

" 1. It appears, that the mountain Schehallien exerts a sensible attraction; therefore, from the rules of philosophizing, we are to conclude, that every mountain, and indeed every particle of the earth, is endowed with the same property, in proportion to its quantity of matter.

" 2. The law of the variation of this force, in the inverse ratio of the squares of the distances, as laid down by Sir Isaac Newton, is also confirmed by this experiment. For if the force of attraction of the hill had been only to that of the earth, as the matter in the hill to that of the earth, and had not been greatly increased by the near approach to its centre, the attraction thereof must have been wholly insensible. But now, by only supposing the mean density of the earth to be double to that of the hill, which seems very probable from other considerations, the attraction of the hill will be reconciled to the general law of the variation of attraction in the inverse duplicate ratio of the distances, as deduced by Sir Isaac Newton from the comparison of the motion of the heavenly bodies with the force of gravity at the surface of the earth; and the analogy of nature will be preserved.

" 3. We may now, therefore, be allowed to admit this law, and to acknowledge, that the mean density of the earth is at least double of that at the surface; and consequently that the density of the internal parts of the earth is much greater than near the surface. Hence also, the whole quantity of matter in the earth will be at least as great again, as if it had been all composed of matter of the same density with that at the

surface; or will be about four or five times as great as Mountains if it were all composed of water.—This conclusion, Mr Maskelyne adds, is totally contrary to the hypothesis of some naturalists, who suppose the earth to be only a great hollow shell of matter; supporting itself from the property of an arch, with an immense vacuity in the midst of it. But, were that the case, the attraction of mountains, and even smaller inequalities in the earth's surface, would be very great, contrary to experiment, and would affect the measures of the degrees of the meridian much more than we find they do; and the variation of gravity, in different latitudes, in going from the equator to the poles, as found by pendulums, would not be near so regular as it has been found by experiment to be.

" 4. As mountains are by these experiments found capable of producing sensible deflections of the plumb lines of astronomical instruments; it becomes a matter of great importance, in the mensuration of degrees in the meridian, either to choose places where the irregular attraction of the elevated parts may be small; or where, by their situation, they may compensate or counteract the effects of each other."

For measuring the heights of mountains, see BAROMETER.

Burning Mountains. See ÆTNA, HÆCLA, VESUVIUS; see also VOLCANO, GEOLOGY Index.

Marble Mountains. Of these there are great numbers in Egypt, from which, though immense quantities have been carried off for the multitude of great works erected by the ancient Egyptians; yet in the opinion of Mr Bruce, who passed by them in his journey to Abyssinia, there is still a sufficient supply to build Rome, Athens, Corinth, Syracuse, Memphis, Alexandria, and half a dozen more of such cities.

The first mountain of this kind mentioned by Mr Bruce is one opposite to Terfowey, consisting partly of green marble, partly of granite, with a red blush upon a gray ground, and square oblong spots. Here he saw a monstrous obelisk of marble very nearly square, broken at the end, and nearly 30 feet long and 19 feet in the face. Throughout the plain there were scattered small pieces of jasper, with green, white, and red spots, called in Italy diapro sanguineo; and all the mountains upon that side seemed to consist of the same materials. From Mr Bruce's description of these mountains, it would appear that they are composed of serpentine, and not of calcareous marble.

Written Mountain, Mountain of Inscriptions, or Jebel-al-Mokaueb, a supposed mountain, or chain of mountains, in the wilderness of Sinai; on which, for a great extent of space, the marble of which the mountain consists is inscribed with innumerable characters, reaching from the ground sometimes to the height of 12 or 14 feet. These were mentioned by a Greek author in the third century, and some of them have been copied by Pococke and other late travellers; but, after all, there is still a very great uncertainty even of the existence of such mountain or mountains. The vast number of these inscriptions, the desert place in which they are found, and the length of time requisite for executing the task, have induced a notion by no means unnatural, that they are the work of the Israelites during their forty years wandering in the wilderness. Others are of opinion that they contain nothing of any importance,

Mountains: importance, but consist merely of the names of travellers and the dates of their journeys.

M. Niebuhr, who visited this country during his travels in the east, made every attempt in his power, though without success, to obtain a sight of this celebrated mountain. On applying to some Greeks at Suez, they all declared that they knew nothing of the written mountain: they, however, directed him to an Arabian sheik, who had passed all his lifetime in travelling between Suez and Mount Sinai; but he knew no more of it than the former. Understanding, however, that a considerable reward would be given to any person who would conduct them thither, this Arab directed them to another; who pretended not only to know that mountain, but all others upon which there were any inscriptions throughout the desert. On inquiring particularly, however, our travellers found that he was not to be depended upon; so that they were obliged to have recourse to a fourth sheik, who by his conversation convinced them that he had seen mountains with inscriptions in unknown characters upon them. It does not appear, however, that this person was very capable, more than the rest, of leading them to the place they so much wished for; though he conducted them to some rocks upon which there were inscriptions in unknown characters. They are most numerous in a narrow pass between two mountains named Om-er-rifstein; and, says M. Niebuhr, "the pretended Jibel-el-Mokatteb may possibly be in its neighbourhood." Some of these inscriptions were copied by our author; but he does not look upon them to be of any consequence. "They seem (says he) to have been executed at idle hours by travellers, who were satisfied with cutting the unpolished rock with any pointed instrument, adding to their names and the date of their journeys some rude figures, which bespeak the hand of a people but little skilled in the arts. When such inscriptions are executed with the design of transmitting to posterity the memory of such events as might afford instructive lessons, greater care is generally taken in the preparation of the stones, and the inscriptions are engraven with more regularity."

When M. Niebuhr arrived at last at the mountain to which the sheik had promised to conduct him, he did not find any inscriptions; but on climbing up to the top, he found out an Egyptian cemetery, the stones of which were covered with hieroglyphics. The tomb stones are from five to seven feet in length, some standing on end and others lying flat; and "the more carefully they are examined (says he), the more certainly do they appear to be sepulchral stones, having epitaphs inscribed on them. In the middle of these stones is a building, of which only the walls now remain; and within it are likewise a great many of the sepulchral stones. At one end of the building seems to have been a small chamber, of which the roof still remains. It is supported upon square pillars; and these, as well as the walls of the chamber, are covered with hieroglyphic inscriptions. Through the whole building are various busts executed in the manner of the ancient Egyptians. The sepulchral stones and the busts are of hard and fine grained sand stone." M. Niebuhr is of opinion that this cemetery was not the work of the Egyptians themselves, but of some colony which came from Egypt, and had adopted the manners and customs

of the people. He supposes that it might have been built by the Arabs, who had conquered Egypt under the shepherd kings, and adopted the Egyptian manners during their residence there. As it must have belonged to an opulent city, however, he owns that there is a great difficulty in accounting for the existence of such a city in the midst of a desert.

The translator of Volney's travels ascribes these inscriptions to the pilgrims who visit Mount Sinai. But to this, as well as to every other conjecture, there is this objection, that whether the inscriptions be well executed or not, whether they contain matters of importance or not, they ought to have been written in a language which somebody could understand; but from the copies that have been taken of them by Dr Pococke and others, it does not appear that they could be explained either by him or any other person.

When Dr Clayton, bishop of Cloyne, visited this part of the world about the year 1723, he expressed the greatest desire to have the matter concerning this written mountain or mountains ascertained, and even made an offer of 5000. sterling to any literary person who would undertake the journey and endeavour to decipher the inscriptions; but no such person has appeared, and the existence of the mountains is testified only by the superior of a convent at Cairo, who gave that mentioned in the beginning of this article. Until that part of the world, therefore, become more accessible to travellers, there is but little hope that we can come to any certainty in the matter. M. Niebuhr plainly, from his own accounts, had not influence enough with the Arabs to show him almost any thing, as they refused to conduct him even to the summit of Mount Sinai.

White Mountains. See New Hampshire.

Mountains of the Moon, a chain of mountains in Africa, extending between Abyssinia and Monomotapa, and so called from their great height.

Mountains of the Lions, also in Africa, divide Nigeria from Guinea, and extend as far as Ethiopia. They were styled by the ancients the mountains of God, on account of their being greatly subject to thunder and lightning.

Mountain of Forty Days; a mountain of Judea, situated in the plain of Jericho to the north of that city. According to the abbé Mariti's description, the summit of it is covered neither with shrubs, turf, nor earth; it consists of a solid mass of white marble, the surface of which is become yellow by the injuries of the air. "The path by which you ascend to it (says our author) fills one with terror, as it rises with a winning course between two abysses, which the eye dares scarcely behold. This path is at first pretty broad, but it at length becomes so confined, that one can with difficulty place both feet upon it at the same time. When we had ascended a little higher, we found an Arab stretched out on the path, who made us pay a certain toll for our passage. Here the traveller requires courage. One of the parapets of the path being broke, we clung to the part which remained until we had reached a small grotto, situated very commodiously, as it gave us an opportunity of recovering our breath. When we had rested ourselves a little, we pursued our course, which became still more dangerous. Suspended almost from the rock, and having before our eyes all the horror of the

Mourning. the precipice, we could advance only by dragging one foot after the other; so that had the smallest fragment given way under us, we should have been hurried to the bottom of this frightful abyss.

"This mountain is one of the highest in the province, and one of its most sacred places. It takes its name from the rigorous fast which Christ observed here after having triumphed over the vanities of the world and the power of hell. In remembrance of this miracle, a chapel was formerly constructed on the summit of the mountain. It may be seen from the plain, but we could not approach it, as the path was almost entirely destroyed. It, however, may be accessible on the other side of the mountain, which we did not visit. A great many scattered grottos are seen here; in one of which, according to Quaresmius, were deposited the bodies of several anchorites, which are still entire. I have heard the same thing asserted in the country, but I could never meet with any person who had seen them. Here we enjoyed the most beautiful prospect imaginable. This part of the mountain of Forty Days overlooks the mountains of Arabia, the country of Gilead, the country of the Ammonites, the plains of Moab, the plain of Jericho, the river Jordan, and the whole extent of the Dead sea. It was here that the devil said to the Son of God, 'All these kingdoms will I give thee, if thou wilt fall down and worship me.'"