ith flat summits sometimes rest on the base of primitive mountains; and contain marble, fossils, and limestone. When mountains of the same kind possess a round and more regular shape, they consist of chalk and other calcareous and friable substances arranged in strata. Granite-argillaceous mountains, like those of Shemnitz, generally form metallic districts. Hills composed of brown free-stone everywhere present irregular points, indicating broken strata and heaps of rubbish.
Dr Pallas (in the systematic part of the Memoir above mentioned, concerning the substances of which the highest mountains are composed) lays it down as an axiom, that the highest mountains of the globe forming continued chains, are composed of that rock which is called granite, the base of which is always a quartz, with a greater or smaller mixture of feldspar, mica, and small scherls, scattered without order, and in irregular fragments of different sizes. This old rock, and the land arising from its decomposition, form the base of all continents. Granite is found below mountains composed of strata (this observation is not applicable to the courses of mountains formed by strata); it constitutes the large protuberances, and as it were the heart, of the greatest Alps in the known world; hence we may with the greatest probability infer, that this rock forms the principal ingredient in the internal composition of our globe. It is never found in regular strata, but in huge masses and in shapeless blocks; its origin is prior to that of all animated beings; it exhibits not the smallest traces of petrification, and seems not to have received the least impression from any organized substance. High eminences, whether in continued chains or in the form of steep peaks, are never covered with clayey or calcareous strata, deriving their origin from the sea; but appear to have been from their very first formation elevated above the level of the ocean. The sides of these great chains are for the most part covered with schistous belts, and surrounded with mountains of the second and third orders. This is proved by the Uralic and Altai chains, which have been traced by Dr Pallas. Such is the system proposed by this author. The high or primitive and ancient mountains, which have existed from the beginning of time, are granitoid; the schistous mountains, which he gives the name of secondary, have arisen on the sides of the primitive by the decomposition of the granite; and those which he calls tertiary mountains, or mountains of the third order, are nothing but substances deposited by the sea, and raised up by volcanoes, or swept away by a violent eruption, a powerful inundation, or an universal deluge. This hypothesis concerning the formation of mountains is borrowed from nature itself, and appears to be confirmed by many facts in natural history.
We shall now proceed to state the height of most of the primitive mountains; an object no less worthy of attention than their structure and variety.
According to M. Pontoppidan, the highest mountains in Norway are 3000 toises in height. According to M. Brovallius, the highest mountains in Sweden are 2333 toises. It is supposed, however, that both these calculations are erroneous.
From the Memoirs of the Academy of Sciences at Paris, it appears, that the mountains in France most elevated above the surface of the Mediterranean are the Puy-de-Dome, which is 817 toises, and the Mont d'Or, which is 1048 toises. These two mountains are in Auvergne, and are supposed to be extinguished volcanoes. Mount Cantal is 993 toises high; Mount Ventoux is 1036; the south peak of Canigou in the Pyrenees, according to M. de Rocheblave, is 1442; and according to M. de Plantade, 1453; and Saint Barthélemy is 1184.
M. Needham observes, that the highest Alps in Savoy are the convent of the great Saint Bernard, at the point of the rock to the south-west of that mountain, which is 1274 toises; Mount Séréné, which is 1283; and Mount Tourne, which is 1683. According to the measurement of the English observer, the peak or needle of Argentiere is 2094 toises high. M. Facio de Duiller and M Duluc make the ridge of Mont Blanc 2213 toises; but according to the observation of M. Shuckburgh, its elevation is 2447 toises one foot (by M. de Saufure's measurement 2426 toises) above the level of the Mediterranean.
The principal mountains of the Alps are among the most elevated in the world; and particularly Mont Blanc, that enormous mass of granite, which is situated in the centre of the Alps, and the access to which is rendered so difficult by the sharp peaks, walls of ice, and everlasting snows wherewith it is covered, is the highest. highest mountain which has been measured either in Europe, Asia, or Africa. The altitude of the Alps of Switzerland has been ascertained by different philosophers; we shall content ourselves with mentioning the most remarkable of those mountains covered with snow, which in Switzerland are called Gletschers or Glaciers. St Gotthard, according to Scheuchzer, is 1650 toises; and Lignon, near the lake of Como, north-east, is, according to Pini, 1486 toises in height.
M. Palumot, engineer to the king of the French, justly observes, that the heights assigned by Mikheli to the mountains of Switzerland appear rather to be ideal computations than founded on observations. An opinion of them may be formed from the following:
According to this author, Mount Pilate or Frakmont, in the district of Lucerne, is 1403 toises in height; Mount Cenis, 1445; Raukhtok, 1760; the Nolle ridge of Titlisberg, 2001; Chemi, 2421; Grimselberg, in the canton of Berne, 2539; the Cornera, part of Louxmanier, 2654; Fource, 2669; Schreckhorn, 2743; and St Gotthard, at its most elevated point, 2750. Mikheli likewise reckons 20 other mountains, the height of which exceeds 2000 toises. The reader may consult the Table comparative des hauteurs des principales montagnes, by M. Palumot (Journal de Physique, September 1783).
Throughout the globe we will not perhaps meet with higher mountains than those of Peru, which go by the name of Cordilleras de los Andos. According to the observations of the academicians sent to South America in 1735 by the Spanish and French courts to measure a degree of the meridian and to ascertain the true figure of the earth, the principal summits of these extraordinary mountains, which are situated near Quito, and which are constantly covered with snow though they lie under the equator, have the following geometrical elevations above the level of the sea: Quito-Capilote, 1707 toises; El-Corazon, 2470 (c); Cotacachi, 2570; Ek-Atlas, 2730; and Noyambale-orcu, under the line, 3030. All the other mountains have been, or still are, volcanoes. The following is an enumeration of them, together with their several heights:
Pichincha, 2430; Cargavi-ralo, 2450; Sinchonalagon or Sinchoulagon, 2570; Sangai, 2680; Illinika 2717; Cotopaxi, 2950; Antifana, 3020; Cagambeorcon, situated under the line, 3030; Cimborazo or Chimborazo, 3220. The last mentioned mountain, which forms part of the Cordilleras in Peru, is one of the largest and probably the highest in the world. It is seen at sea from the gulph of Guayaquil, which is more than 60 leagues distant.
Other very elevated mountains are Mount Sinai in Japan; Mount Caucasus in Asia; the southern peak of the Pyrenees; the peak of Teneriffe in one of the Canary islands, which according to M. Bouguer is 2000 toises (according to later observations, made by M. M. de Verdun, de Borda, and Pingré, French academicians, in 1754, the peak of Teyde, more commonly known by the name of the peak of Teneriffe, is only 1904 toises perpendicular height above the level of the sea); Mount Gibel or Erna in Sicily is 1672 toises; St George's peak in the Azores; Adam's peak in Ceylon; the mountains of the Moon; Mounts Athos, Olympus, Taurus, and Etna; Mount Cenis in the Alps on the road from France to Italy, is 1460 toises; the Great and Little Atlas; and many others, on the top of which we feel, even in the middle of summer, a more piercing cold than that of the severest frosts of our climates. After this, it cannot appear wonderful that the vapours which reach so great heights are there concealed; and that the summits of these mountains, even in the warmest climates, are constantly covered with snow, while the inhabitants of the plain enjoy a temperate atmosphere, or are subject to extreme heat. The height of these mountains, added to their being placed on the most elevated parts of the globe, is the chief cause of the phenomena peculiar to them. In that part of Asia which is separated by the chain of mountains called the Ghauts, there are two very different seasons at one and the same time. While it is winter on the Malabar coast, for instance, the Coromandel coast, which has the same degree of elevation, and in some places is only 20 leagues distant, enjoys an agreeable spring or the temperature of autumn. The traveller in the Alps generally experiences, even in summer, the four seasons of the year. In the Andes we meet with a change of temperature no less curious; for as we descend from their summit to their base, we experience all the varieties of heat and cold which are felt in every climate of the earth, at whatever season (p). There are many other mountainous countries in which we pass at once from a serene sky to dreadful.
(c) This is the greatest height to which any person is known to have ascended in America; the greatest elevation which has been reached in the Alps is the top of Mont-Blanc, which is 2426 toises, and which Dr Paccard ascended on the 8th of August 1786. M. de Saussure arrived there likewise on the 3d of August 1787, accompanied by 17 persons.
(d) The more we are elevated above the surface of the earth, it becomes the colder; and accordingly the tops of the highest mountains are always covered with snow. At the height of about 2300 toises above the level of the sea no plant whatever is found to grow; and it appears from the observations of MM. de la Condamine, Bouguer, Godin, Dom George Juan, and Dom Antonio de Ulloa, the academicians sent to Quito in 1735, that at the height of 2424 the snow is perpetual, and never melts at any time of the year even under the equator. The congelation begins and continues in all the mountains of the Cordilleras at the same height above the level of the sea, which is determined by an equal elevation of the mercury in the barometer. But from experiments which have been made, Sir Isaac Newton concludes, that the density of the atmosphere at any height is as the weight of the incumbent air, that is, as the height of the mercury in the barometer; and consequently the density of the air is the same in the whole region of the atmosphere, where the congelation is continual, and where that perpetual cold commences which is felt on all mountains. Above this constant height the density of the air continues to diminish, and the cold becomes greater and greater till... dreadful storms and tempests. It cannot therefore be doubted, that mountains have a great influence on the temperature of the countries to which they belong, by stopping the course of certain winds, by forming barriers to the clouds, by reflecting the sun's rays, and by serving as elevated conductors to the electricity of the atmosphere. It was formerly said by travellers, that on the peak of Tenerife they found that brandy lost its strength; that spirit of wine became almost infipid; that pepper, ginger, and salt, had little or no taste when applied to the tongue; but, it was alleged, that Canary wines still retained their taste on that mountain. These stories appeared too marvellous not to require new experiments; and MM. de Lamanon and Mongez, who visited this peak in 1785, tell us, that the flavour and taste of liquors appeared to have sustained no loss at that height: (See the experiments made on the Pic du Midi in the Pyrenees by M. Darcey, in the Journal de Physique for November 1776; and a journey to the peak of Tenerife, in the same Journal for August 1785.) At the foot, and sometimes at the middle, of those lofty mountains, the tops of which are always covered with snow, we frequently find springs which begin to run in May and dry up in September. When the sun approaches near enough to the tropic to warm the summits of these mountains, the snow with which they are covered melts, filtrates through their interior part, and issues forth at their base. The only trees which grow on mountains of this kind are firs, pines, and other resinous trees; and the grass becomes shorter towards their summit.
Mountains were not formed to be an useless load upon the earth, but evidently answer very important purposes; and we cannot enough admire their form and that kind of harmony which is discernible in their arrangement. Some of them, vomiting out fire or smoke, lava, and sulphur, indicate that they in some measure answer the purpose of a chimney to something within the earth, which, if confined, would bury it in pieces: (See Volcano.) Of this kind are Mount Hecla in Iceland, Mount Etna in Sicily, Mount Vesuvius in the kingdom of Naples, Pichincha and Cotopaxi in America, &c. Others, the summits of which reach into the clouds, attract and absorb the vapours of the sea, &c. which float in the air. It is observed by M. l'Abbé Palisson, that storms are most frequent at the foot of those high mountains which form extensive chains. Their enormous masses, which seem to support the heavens on their shoulders, arrest and fix the different meteors as they are formed. The clouds, in like manner, driven by the winds from different points of the horizon, there meet with impenetrable barriers, are there accumulated in great quantity, and remain suspended on these bulwarks of the globe's surface, till the agitation of the atmosphere succeeding the calm, produces storms, which are so much the more terrible that they cannot expand and be dispersed but with great difficulty. They are commonly repelled from the mountains; and are then observed to spread over whole countries, to dissolve with peals of thunder, and to fall down in destructive hail-showers fatal to the harvest and to the whole produce of the fields. This scourge is peculiarly dreadful during the seasons of spring and summer, when a sufficient quantity of snow remains on the mountains to cool the atmosphere.
Some chains of mountains have openings; in others they are wanting: of the former kind are the straits of Thermopylae, the Caspian straits, the pas of the Cordilleras, &c.
Those spaces which separate the tops of mountains are so many basins destined for the reception of the condensed mists, and of the clouds precipitated into rain. The bowels of mountains appear to be great and inexhaustible reservoirs, and to contain subterraneous canals and lateral openings formed by the hand of nature, that the several species of animals may be supplied with drink, that the earth may be fertilized, and that nourishment may be afforded for the growth of vegetables. The streams and rivers descend from the ridges of mountains, the declivities of which form so many inclined plains: Thus we find the Alps give rise to the Rhine, the Danube, the Rhone, and the Po. With regard to the wonderful structure, by means of which so many advantages are obtained, see the articles Earth, Springs, &c.
Mountains of the first order form vast solitudes and horrid deserts, where the habitations of men are not to be seen, and their footsteps are seldom to be traced. By their grandeur, their elevation, the variety of their positions, the sublime and awful exhibition of wonders which they contain, they elevate the mind and fire the imagination of the observer. But these majestic eminences have other advantages which deserve our attention. They form the common retreat of a multitude of wild beasts, which are subservient to our use: there the bear, the lynx, the ermine, the martin, the fox, and many other animals, the skin of which we employ for furs, take up their abode; and thither the eagle and the vulture resort in safety. Mountains likewise afford nourishment to rein-deer, buffaloes, fallow-deer, roe-deer, and chamois; and they are visited by birds of passage which, under the guidance of instinct, follow the shortest road to the place of their destination. They produce medicinal plants, which almost never grow elsewhere. In Switzerland, they are also covered with deep forests, which, by the great height of the trees, announce their antiquity. They afford both timber and fuel, and supply the inhabitants with abundance of excellent pasture for their cattle during the whole summer. The most precious stones, both for brilliancy and hardness, acquire their forms and colours in the fissures of the rocks; the internal rents of mountains are filled and in a manner cemented by different metallic substances; while the grottoes are furnished with numerous conglomerations, shining... shining crystals, and substances of an extraordinary nature and figure. In short, every thing concurrs to show, that the existence of mountains is absolutely necessary; and that in order to acquire a proper knowledge of them, they must be considered in many different points of view. Their position, their direction, their elevation, the extent of their base, their figure, their various external windings, their internal structure; in a word, every thing relating to the theory of the globe, and to the different temperatures of the atmosphere, must engage the observer's attention; and by studying and carefully examining the general constitution of mountains, the particular facts which they present to our view, their influence, their action on the atmosphere, the different substances of which they are composed, together with the arrangement and mixture of these substances, we may at length discover the true mechanism of the earth. The reader may consult the Essais Sur l'étude des Montagnes; Journal de M. l'Abbé Rozier, November 1773.
The difficulty and danger of ascending to the tops of mountains proceeds not from the thinness of the air; as has been commonly reported; but the reason is, that they rise with such a rugged and precipitate ascent, that they are utterly inaccessible. In some places they appear like a great wall of 600 or 700 feet high; in others, there stick out enormous rocks, that hang upon the brow of the steep, and every moment threaten destruction to the traveller below.
In this manner almost all the tops of the highest mountains are bare and pointed; and this naturally proceeds from their being so continually assaulted by thunders and tempests. All the earthy substances with which they might have been once covered, have for ages been washed away from their summits; and nothing is left remaining but immense rocks, which no tempest has hitherto been able to destroy.
Nevertheless, time is every day and every hour making depredations; and huge fragments are seen tumbling down the precipices, either loosened from the summit by the frost or rains, or struck down by lightning. Nothing can exhibit a more terrible picture than one of these enormous rocks, commonly larger than an house, falling from its height with a noise louder than thunder, and rolling down the side of the mountain. Dr Plot tells us of one in particular, which being loosened from its bed, tumbled down the precipice, and was partly shattered into a thousand pieces. Notwithstanding, one of the largest fragments of the same, still preserving its motion, travelled over the plain below, crossed a rivulet in the midst, and at last dropped on the other side of the bank! These fragments, as was said, are often struck off by lightning and sometimes undermined by rains; but the most usual manner in which they are disunited from the mountain is by frost: the rains infusing between the interstices of the mountain, continue there until there comes a frost; and then, when converted into ice, the water swells with an irresistible force, and produces the same effect as gun-powder, splitting the most solid rocks, and thus shattering the summits of the mountain.
But not rocks alone, but whole mountains, are, by various causes, disunited from each other. We see, in many parts of the Alps, amazing clefts, the sides of which so exactly correspond with the opposite, that no doubt can be entertained of their having been once joined together. At Cajeta in Italy, a mountain was split in this manner by an earthquake; and there is a passage opened through it, that appears as if elaborately done by the industry of man. In the Andes these breaches are frequently seen. That at Thermopylae in Greece has been long famous. The mountain of the Troglodytes in Arabia has thus a passage through it; and that in Savoy, which nature began and which Victor Amadeus completed, is an instance of the same kind.
We have accounts of some of these disruptions immediately after their happening. "In the month of June, in the year 1714, a part of the mountain of Diableret, in the district of Valais in France, suddenly fell down, between two and three o'clock in the afternoon, the weather being very calm and serene. It was of a conical figure, and destroyed 55 cottages in the fall. Fifteen persons, together with about 100 beasts, were also crushed beneath its ruins, which covered an extent of a good league square. The dust it occasioned instantly covered all the neighbourhood in darkness. The heaps of rubbish were more than 300 feet high. They stopped the current of a river that ran along the plain, which now is formed into several new and deep lakes. There appeared, through the whole of this rubbish, none of those substances that seemed to indicate that this disruption had been made by means of subterraneous fires. Most probably, the base of this rocky mountain was rotted and decayed; and thus fell, without any extraneous violence." In the same manner, in the year 1618, the town of Pleurs in France was buried beneath a rocky mountain, at the foot of which it was situated.
These accidents, and many more that might be enumerated of the same kind, have been produced by various causes; by earthquakes, as in the mountain at Cajeta; or by being decayed at the bottom, as at Diableret. But the most general way is, by the foundation of one part of the mountain being followed by waters, and thus wanting a support, breaking from the other. Thus it generally has been found in the great chasms in the Alps; and thus it almost always is known in those disruptions of hills which are known by the name of land-slips. These are nothing more than the sliding down of an higher piece of ground, dislocated from its situation by subterraneous inundations, and settling itself upon the plain below.
There is not an appearance in all nature that so much astonished our ancestors as these land-slips. In fact, to behold a large upland, with its houses, its corn, and cattle, at once loosed from its place, and floating as it were upon the subjacent water; to behold it quitting its ancient situation, and travelling forward like a ship, in quest of new adventures; this is certainly one of the most extraordinary appearances that can be imagined; and, to a people ignorant of the powers of nature, might well be considered as a prodigy. Accordingly, we find all our old historians mentioning it as an omen of approaching calamities. In this more enlightened age, however, its cause is very well known; and, instead of exciting ominous apprehensions in the populace, it only gives rise to some very ridiculous law-suits among them, about whose the property shall be; whether the land which has thus slipped shall belong to the original possessor or to him upon whose grounds it has encroached and settled. What has been the determination of the judges is not so well known; but the circumstances of the slips themselves have been minutely enough and exactly described.
In the lands of Slatberg, in the kingdom of Ireland, there stood a declivity gradually ascending for near half a mile. In the year 1712, and on the 16th of March, the inhabitants perceived a crack on its side, somewhat like a furrow made with a plough, which they imputed to the effects of lightning, as there had been thunder the night before. However, on the evening of the same day, they were surprised to hear an hideous confused noise issuing all round from the side of the hill; and their curiosity being raised, they referred to the place. There, to their amazement, they found the earth for near five acres all in gentle motion, and sliding down the hill upon the subjacent plain. This motion continued the remaining part of the day and the whole night: nor did the noise cease during the whole time; proceeding, probably, from the attrition of the ground beneath. The day following, however, this strange journey down the hill ceased entirely; and above an acre of the meadow below was found covered with what before composed a part of the declivity.
However, these slips, when a whole mountain's side seems to descend, happen but very rarely. There are some of another kind, however, much more common; and, as they are always sudden, much more dangerous. These are snow-slips, well-known, and greatly dreaded by travellers. It often happens, that when snow has long been accumulated on the tops and on the sides of mountains, it is borne down the precipice either by means of tempests or its own melting. At first, when loosed, the volume in motion is but small; but it gathers as it continues to roll; and by the time it has reached the habitable parts of the mountain, it is generally grown of enormous bulk. Wherever it rolls, it levels all things in its way, or buries them in unavoidable destruction. Instead of rolling, it sometimes is found to slide along from the top; yet even thus it is generally as fatal as before. Nevertheless, we have had an instance, a few years ago, of a small family in Germany that lived for above a fortnight beneath one of these snow-slips. Although they were buried during that whole time in utter darkness, and under a bed of some hundred feet deep, yet they were luckily taken out alive, the weight of the snow being supported by a beam that kept up the roof, and nourishment supplied them by the milk of a she-goat that was buried under the same ruin.
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 Mountain's 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 proportionally 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 (v):" yet no attempt to ascertain this matter by actual experiment was made till about the year 1738; when the French academicians, particularly M. Bouguer and Condamin, 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 contrary-wise at 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.
(n) By a very easy calculation it is found that such a mountain would attract the plumb-line 1' 18" from the perpendicular. 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 contrarywise; 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 inference 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 philosophising, 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 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 attractions 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 the article Barometer.
Burning Mountains. See Etna, Hecla, Vesuvius, and Volcano.
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 such an abundant supply, that it would be sufficient 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 grey 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 diaspro sangueo; and all the mountains upon that side seemed to consist of the same materials. Here also were quantities of small pieces of granite of various kinds, as well as porphyry, which had been carried down by a torrent, probably from the ancient quarries. These pieces were white mixed with black spots, and red with green veins and black spots. All the other mountains on the right hand were of red marble, but no great beauty; those on the opposite side being green marble, probably of the serpentine kind. This, he says, was one of the most extraordinary sights he ever saw. The former mountains were of a considerable height, without a tree, shrub, or blade of grass upon them; and this looked exactly as if it had been covered over with Havannah and Brazil fluff. Proceeding farther on, he entered another delite with mountains of green marble on every side. The highest he saw appeared to be composed of serpentine marble; having a large vein of green jasper spotted with red running through about one-third of its thickness. It was extremely hard; so that it did not yield to the blows of a hammer, though it was evident that it had formerly been quarried; and there were channels for bringing water, which terminated nated in this quarry of jasper; "a proof (says Mr Bruce) that water was one of the means used in cutting those hard stones."
On these mountains, our author observes, that "the porphyry shows itself by a fine purple sand without any globs upon it, though the colour is very agreeable to the eye. It is mixed with the white sand and fixed marble of the plains. Green and unvariegated marble is also found in the same mountain with the porphyry. The marble is brittle for some inches where the two veins meet; but the porphyry is as hard as in other places. The granite appears like a dirty brown stone covered with sand; but this is only the change made upon it by the sun and weather; for on breaking it, the colour appears to be grey with black spots, and a reddish cast on the surface. The reddish colour appears to be impaired by exposure to the atmosphere; but is recovered upon polishing it anew. It is in greater quantity than the porphyry, and nearer to the Red Sea. The granite is next to the porphyry, but never joined with it in the same mountain. Being covered with a reddish sand, it looks as if the whole mountain were covered with brick-dust." There is likewise a kind of red marble with white veins, which our author has seen at Rome and likewise in Britain. The common green, called serpentine, looks as if it were covered with Brazil snuff. Along with this green he saw two samples of the beautiful kind called Isabella; one of them with the yellowish cast of Quaker-colour, the other of that bluish cast called dove-colour; and these two seemed to divide the mountains with the serpentine. Here also he saw the vein of jasper; but had not time to determine whether it was the same with that called bloody-jasper or blood-stone or not.
The marble of greatest value, however, is that called Verde Antico, which is of a dark-green colour with white spots. It is found, like the jasper, in the mountains of the plain green serpentine, and is not discoverable by the dust or any particular colour upon it. "First (says Mr Bruce) there is a blue flaky stone exceedingly even and smooth in the grain, solid, and without spots and colour. When broken it is something lighter than a flate, and more beautiful than most kinds of marble; it is like the lava of volcanoes when polished. After lifting this we come to the beds of verde antico; and here the quarrying is very obvious; for it has been uncovered in patches not above 20 feet square. Then, in another part, the green stone has been removed and another pit wrought." In other places of the plain he saw pieces of African marble, but no rocks or mountains of it. He supposes it to be found in the heart of some other coloured marble, and in strata like the jasper and verde antico; and, as he suspects, in the mountains of Isabella marble, especially of the yellowest sort. This vast store of marble is placed on a ridge, whence there is a descent to the east and west, so that it could be conveyed either to the Nile or the Red Sea. The level ground and hard fixed gravel are proper for the heavy carriages; so that any weight whatever might easily be conveyed to the place of embarkation. In the more distant mountains also he observed the same care taken to facilitate the carriage; for the defiles between those mountains he supposes not to be natural but artificial openings; and he observed the roads from them to the Nile to be cut with a descent of about one foot in 50 at most; so that, all the way down, the carriages must have moved with as little draught as possible, at the same time that the vast friction would prevent any undue acceleration; to which also some other means must have contributed: But thus, he thinks, it may be explained how such immense blocks might have been removed as were employed in the ancient Egyptian works.
Mountains of marble and porphyry are not peculiar to Egypt, for they are likewise to be met with in the north of Scotland; and in the Western Isles there are likewise such quantities of these materials to be met with, as, in the opinion of Mr Williams, would be sufficient to serve all Europe.
Written Mountains, Mountain of Inscriptions, or Jibel-el-Mokatteb, 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; notwithstanding which, there is still a very great uncertainty even of the existence of such mountains 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, has 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, but consist merely of the names of travellers and the dates of their journeys.
M. Niebuhr, who visited this country about 30 years ago, 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-riftein; 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 Mountain, 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 there any inscriptions; but on climbing up to the top, he found nothing there but 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. Throughout 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 sandstone." 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 which 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 Clogher, 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 L.500 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 mention 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 anything, 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 themselves between Abyssinia and Monomotapa, and receiving the above denomination from their great height.
Mountains of the Lions, also in Africa, divide Nigritia 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 Abbe 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 winding 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 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.
Proceeding a little farther, we found a second grotto, the entrance of which was about nine feet in breadth. It would be of considerable size, were not about two-thirds of it filled up by part of the roof, which had tumbled down. This grotto conduits to another, which we had the curiosity to enter, but we were almost stifled by the great number of bats which were fluttering up and down in it. Being drowsy of retreating almost as soon as we had entered, they flew in such numbers around us, that they in a manner covered our whole bodies; but they luckily made a passage for themselves, and suffered us to breathe with freedom. By the glimmering light which reached this grotto, we perceived that the bottom of it was covered to the height of a hand-breadth with the excrements of these animals; and we remarked some niches in the sides of it, which gave us reason to conclude, that it had once served as a sepulchre to the ancient anchorites. This is the more probable, as the other grotto appears by the remains of an altar and of some Greek paintings to have been formerly a church. In the right corner there is a large cistern, the platter of which retains its original solidity, though broken... Mountains, broken in a few places. In the left corner there is Mourning, a small flail which conduits to a third grotto. This is much longer and broader than any of the former, and its walls are ornamented also with Greek paint- ings, which represent the twelve apostles in their na- tural size. Their figures, however, are so much chan- ged, that one could scarcely distinguish who they are, were it not that their names are written in Greek char- acters upon the glory which surrounds their heads.— At the farther end of this grotto stands a square altar a little damaged; above which is an oval painting of the Annunciation, in perfect preservation. The chief has been employed to render these grottos regular and smooth; and it appears that they were inhabited by a certain number of hermits, who devoted themselves to a life of contemplation. No writer has been able to tell us who the founder of this hermitage was.— Nicephorus and Eusebius, who have described all the churches and religious places of Palestine and Judea, do not speak of these chapels.
"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 en- tirely destroyed. It, however, may be accessible on the other side of the mountain, which we did not vi- sit. A great many scattered grottos are seen here; in one of which, according to Quarefminus, were depo- sited 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.'"