depth, the other fifteen. They were shaped like an inverted cone, and the matter with which they were covered was similar to the rest of the surface, but they emitted neither smoke nor heat. The ascent of our adventurers was accomplished with more difficulty, though perhaps with less danger, than the descent. It also occupied a greater space of time; for they could only ascend one at a time after considerable intervals, for fear of burying, under torrents of dust and volcanic matters, those who immediately succeeded. Both the inside of the crater and the base of many volcanos consist of lava, either entire or decomposed nearly as low as the level of the sea; but they finally rest either on granite, as in Peru, or schistus, as the extinguished volcanos of Hesse and Bohemia, or on limestone, as those of Silesia, mount Vesuvius, &c. No ore is found in these mountains, except that of iron, of which lava contams from twenty to twenty-five parts in the hundred, and some detached fragments of the ores of copper, antimony, and arsenic. Vesuvius ejected, from the year 1779 to 1783 309,658,161, cubic feet of matter of different kinds; we must therefore conclude the seat of these fires to be several miles below the level of the sea; and as iron makes from one-fourth to one-fifth of these ejections, we may infer that the internal parts of the earth abound much in this metal. One of the best, as well as of the most modern, writers upon this subject is the abbe Spallanzani. In the course of a variety of interesting enquiries upon the spot, he examined minutely into the nature of the gasses poured forth; and observed that the stony substances thrown forth are invariably, when completely heated by the subterraneous fire, rarified, inflated, and rendered cellular, by their elasticity, an effect which is observable in numbers of lavas, glasses, and enameis, ejected during eruptions: and he discovered, in addition, that their violence continually raised the liquified matter from the interior of the craters to their very borders, over which it Moved at each impulse. He was, at the same time, equally attentive to the nature and force of the fire which acts in the buse is of volcanic mountains; and, in the course of his researches, discovered that the immense mountains of Vesuvius, Etna, the Eolian Islaudis, and Ischia, are composed of rocks that have been liquified, and even vitrified, by the vilence of the subterraneous conflagration. "What fire," he exclaims, "can we produce equivalent to these effects!" Humble, however, as all experiments appear with our limited means, this venerable philosopher justly thought imperfect knowledge of volcanos preferable to contented ignorance, and, undismayed by the magnitude of the object, proceeded to ascertain, as far as possible, what man is permitted to know on this terrific subject. "I have," he observes, "discovered, that the fire of the glass-furnace will completely refuse the vitrifications, enamels, pumices, scoriæ, and lavas, of these and other volcanic countries. The same will, in like manner, vitrify rocks congenerous to those from which these mountains have originated, by the means of subterranean conflagrations. A less intense fire, on the contrary, produces no such effect on any of these substances. Determined to exercise the most rigorous research, and to ascertain, with the greatest possible precision, the exact degree of heat requisite to produce the above effects, he had recourse to the pyrometer of Wedgwood, which he compliments and praises by saying, nothing could be better adapted for his purpose. The terrific appearance of a volcano in eruption is so appalling, so grand, and altogether so wonderful, that it is by no means astonishing the world should suppose the vast volumes of smoke, ignited matter, and stones, hurled into the air with inconceivable violence and rapidity, exclusive of the torrents of liquified substances which roll down its sides in solemn and destructive majesty, were caused by more powerful fires than those man has been permitted to kindle; in saying the world, we wish to be understood as meaning those who have seen or read of eruptions without examining the subject further. Of natural philosophers, there were many who coincided with this general opinion; and others have maintained the direct contrary supposition, asserting that volcanic fires are extremely feeble in their operations: following the example of Spallanzani, we shall give the substance of the arguments of each, in order that the reader may draw his own conclusion. It is evident that we must have recourse to the same rule for ascertaining the intensity of volcanic fires which we make use of in measuring the effects of our fires when in activity on bodies immersed in them; and we have already mentioned, that Wedgwood's pyrometer answers for the purpose, as nearly as the nature of the pursuit will permit; but long before the invention of this instrument attempts were made to attain the object in question, particularly by the academicians of Naples, who at the time of the great eruption, in the year 1737, made an experiment on the lava near the Torre del Greco, in a valley where it had accumulated; and though it had ceased its motion several days, yet retained a heat equal to that of red-hot iron. They formed a piece of lead weighing two ounces, in a conical shape, which they placed on the red-hot surface of the lava; the metal became soft in two minutes and a half, and in one minute more it was completely melted: another piece of lead, in every respect exactly similar, was then deposited on a plate of red-hot iron rendered so by burning coals beneath it, when they found that it required six minutes and a half to soften, and seven and a half to liquify it. Water placed on the lava boiled furiously in three minutes, and on burning coals, one minute later. Judging from these facts, the academicians concluded that lava, though exposed to the external air for some days, and consequently far less intensely heated than when first issuing from the crater, was much more fiery in its nature than red hot iron or burning coals: but this conclusion is obviously incorrect; because the plate of iron, being surrounded by air, could not acquire all the heat which was applied to it; neither was it fair to rest an opinion of this description upon a result produced by a means so unequal, as a vast depth of ignited matter opposed to a thin plate of iron. Prince Cassano, a member of our Royal Society, produced an instance of the violent heat of the lava which issued from Vesuvius to that learned body, which seems more to the purpose than that of the academicians: the torrent of lava alluded to approached a convent of Carmelites; every combustible article was immediately consumed, even before the mass came into contact with it; The cricoid cartilage, anteriorly thick and hard, is increased backwards, in form of a ring unequally truncated; and, in the middle, it is divided into two cavities by a protuberant line. It is firmer than the rest of the cartilages, and forms their basis. From it longitudinal muscular fibres and ligaments descend to the windpipe. The pharynx, connected with each of these cartilages by many muscular layers, receives the larynx into its cavity. From this cartilage a short ligament proceeds to the arytenoid cartilage on each side. The figure of the two arytenoid cartilages is very complex. It spontaneously divides into two parts, of which the lower is larger, and is connected by a moderately concave base with the thick cricoid cartilage, forming a moveable articulation. It sends a process forwards, which separates the glottis, and sustains the inferior part of the ventricle of the larynx. They ascend upwards, of a triangular figure; the posterior base is hollow, and the anterior side is convex, and divided by three furrows. They are extenuated upwards, till they are at last terminated by a pretty thick, oval, cartilaginous head fixed on them. The lower part of these cartilages is connected by numerous muscular fibres, partly transverse, and partly oblique; of which the different directions are evident, though they cannot be separated. These are called the arytenoid muscles. In their upper part, the arytenoid cartilages are separated by a perpendicular chink, which has been improperly by some called the glottis. The arytenoid cartilages are connected with the thyroid by transverse ligaments, for the most part sufficiently strong and elastic, but covered with the common mucous membrane of the larynx. These ligaments arise below the middle of the arytenoid cartilages, and are inserted into the flat angle of the thyroid cartilage, and may be separated from each other, by removing the arytenoid cartilages from being in mutual contact, and may be again brought into contiguity by the cartilages approaching each other. This constitutes the true glottis, and is continuous, but at right angles with the above-mentioned chink. From the same angle of the thyroid cartilage, under a notch, from a firm ligament, a cartilage arises, with an erect slender stalk, of an oval shape, convex before, behind concave, and with its superior extremity reflected backwards and concave. It is kept erect by its own elasticity, so that it rises upright behind the tongue; but it can be so inclined whenever the root of the tongue is pressed backward, that, having become transverse, it completely shuts up and protects the passage into the larynx, which descends between this, the epiglottis, and the arytenoid cartilages. The epiglottis is joined to the tongue by pale membranous fibres, and to the os hvoides by much membranous expansion. It either has no fibres from the thyroarytenoidal and arytenoidal muscles, or they are too minute to counteract its elasticity. At the sides of the ligaments of the glottis, two other upper and softer ligaments, less ten dinous or elastic, proceed parallel from each arytenoid cartilage to the thyroid. Betwixt these two ligaments of each side a peculiar cavity or ventricle descends, having the figure of a compressed parabolic space, extending downwards betwixt the double membrane of the larynx, with its superior orifice, of an ellip tic form, constantly open into the larynx. Lastly, all the internal cavity of the larynx is lined with the same soft, irritable, mucous membrane we before described in the windpipe. This membrane is moistened by a great number of glands. The uppermost are small, and composed of simple glands. They are seated on the anterior convex part of the epiglottis, and send prolongations through its various perforations and larger sinuses, to its concave side, which are there continued into similar firm glands. Moreover, upon the anterior furrowed surface of the arytenoid cartilages there is on each side a gland, of a loose conglomerate fabric, resembling much a gnomon, composed of round acini, doubtless mucous, of which a loose por tion descends on each side as far as the annular cartilage. In the ventricles, there are numer ous mucous sinuses. Lastly, all the internal surface of the larynx is full of large mucous pores. All these glands secrete a thin and watery, but, at the same time, viscid mucous. Has the thyroid gland any similar use? It is of the conglomerate kind, but soft, the coverings of the lobules being much more tender than in the salival glands; it is very large, is anteriorly seated upon the thyroid and cricoid cartilages and windpipe, surrounding with lateral productions the sides of the thyroid; is joined to its companion by an isthmus, which is narrow and emarginated below; and by a middle very thin process it ascends on the fore-part, almost to the os hyoides. This gland is full of a serous, yellowish, and somewhat viscid hu mour. Does it discharge this fluid into the windpipe or into the oesophagus? Into neither. Are ducis certainly known to open? Does it retain its fluid entirely, and afterwards restore it to the veins, like the thymus, which is analogous in its structure? Is it a conglobate gland? That the use of this gland is very considerable appears from the remarkable size of the arteries which it receives from the carotids, and of its inferior ones from the subclavians. The veins return into the jugulars and subclavians. It has a peculiar muscle, not however constant, arising from the margin of the os hyoides, and sometimes from the lower edge of the thyroid cartilage towards the left, which descends with out a fellow, and spreads its tendinous fibres over the gland, upon which also the sternohyoidei and sterno-thyroidei muscles are incum bent. The whole larynx is suspended from the os hyoides, both by ligaments inserted into the superior horns of the thyroid cartilage, and by the middle of its basis, united to the junction of the plates, constituting that cartilage. The larynx, and os hyoides connected with it, may be raised considerably, even half an inch above its mean altitude. This is performed by the biventer muscles, together with the genio-hyoidei, genio-glossi, stylo-glossi, stylo-hyoidei, stylo-pharyngei, thyro-palatini, hyo-thyroidei; either conjunctly or partially. During its elevation, the glottis is rendered narrower, and the ligaments before mentioned approach nearer together. Thus, by the assistance of the action of the arytenoid muscles, both oblique and transverse, the glottis may be accurately closed, so as to resist with an incredible force the pres sure of the whole atmosphere. The whole larynx may also be depressed about half an inch beneath its ordinary situa tion, by the sterno-hyoidei, sterno-thyroidei, and coraco-hyoidei, as they are called: and, when these are in action, by the anterior and posterior crico-thyroidei. By this motion the arytenoid cartilages remove from each other, and the glottis becomes wider, which is also drawn open by the muscles laterally inserted into the arytenoid cartilages, and by the cricoarytenoidei postici and laterales, and thyro-arytenoidei: these also, by resting upon the ventricles of the larynx, are capable of compressing them. The particular cartilages which form the larynx can scarcely be moved separately. From the larynx the air comes into the mouth and nostrils. By the mouth, we here mean that large and irregularly shaped cavity, situated between the soft and hard palates, both concave in the middle, and the muscles lying under them, and the lower jaw. The nostrils ascend forwards above the soft palate; they are two broad cavities, included between the septum medium, and the ossa cavernosa, and some other parts. They are every where bony and cartilaginous. The tongue lies in the middle of the month; it is a broad piece of flesh easily changeable into any kind of figure, and readily moved without delay to any part of the mouth; by its own fleshy fibres, and by the muscles attached either to itself or to the os hyoides, which is joined to it by many fleshy fibres and membranes, it may with great facility be made to assume any position or figure. It is drawn forwards by the genio-glossi and genio-hyoidei muscles; backwards, by the stylo-glossi, stylohyoidei, cerato-glossi, basio-glossi, chondroglossi, and biventer; downwards, by the sterno hyoide and cerato-hyoidei; and upwards, by the stylo-glossi, stylo-hyoidei, by the biventers, and likewise by the mylo-hyoidei. So much for the anatomy. It remains that we demonstrate what effects are produced by air, when expelled, during exspiration, by the powers above described, from the lungs through the windpipe into the larynx, and from thence forced through the glottis into the mouth va nously configured. These effects are, voice, speech, and singing. Sound only is produced when the air is expelled with so great a velocity through the contracted glottis, that it impinges on the ligaments of the glottis, and thus produces in the larynx that tremor, which, being vibratory on account of its elasticity, it conunges and increases. Therefore, from the united vibrations of the ligaments and of the cartilages of the larynx, a sound is produced, which we call the voice, peculiar in every class of animals, and which depends entirely on the larynx and glottis. When there are no vibrations, a whisper is produced. The strength of the voice depends upon the quantity of air exspired, and the narrowness of the glottis; and therefore, upon capacious lungs easily dilatable, an ample, cartilaginous and elastic larynx and windpipe, the free resonance of the nostrils, and a powerful exspiration. But the acuteness or gravity of the tones we observe to arise from various causes. The former proceeds partly from the narrowness, and partly from the tension, of the glottis, and the latter from its relaxation and dilatation. For hence, the air, in a given time, impinges upon the ligaments of the contracted glottis with more numerous undulations, and causes more frequent vibrations; but when the glottis is dilated, the contrary of all this follows. And from the greater tension of the ligaments, the tremors in like manner become more numerous from the same stroke. Therefore to produce an acute sound, the whole larynx is drawn upwards and forwards; and with greater force as the voice is required to be sharper, insomuch that the head itself is sometimes inclined backwards, that the muscles elevating the larynx may exert their full powers. The truth of this is confirmed by experiment; for by applying the fingers to the larynx when acute sounds are emitted, the elevation of the larynx, which is about half an inch for the octave, is easily felt; and by comparative anatomy, which de monstrates the glottis to be very narrow and cartilaginous in singing birds, and wide in hoarse animals, and such as are low or are mute. This is also illustrated by whistling, where the sharpness of the sound evidently proceeds from the contraction of the mouth: and by musical instruments, in which the nar rowness of the opening admitting the air, and the celerity with which it is impelled, are the causes of an acute tone. Gravity of the voice is produced by opposite circumstances, the depression of the larynx by the causes already described; a wide glottis and a very ample larynx. This is proved by the touch, which easily perceives the descent of the larynx in persons singing, in like manner about half an inch for every octave; by the greater gravity of the voice in males, and by the lowest tones of the voice degenerating into a silent breathing. Does every diversity of tone proceed from the length of the ligaments of the glottis, which is augmented when the scutiform cartilage is drawn forwards, and the arytenoid ones backwards? Is it according to this rule that the most acute tones are produced by the ligaments being rendered very tense, and therefore vibrating with great celerity? This is asserted by some late anatomists, from experiments, which have been also repeated by some eminent men: they have observed, that when the chords or ligaments of the glottis are tense, the peculiar voice of every kind of animal is : : produced by blowing air into its trachea that this voice was rendered more acute by stretching the ligaments, and more grave by loosening them that by shutting the whole ligament, the voice was suppressed; by shutting the half, the voice was rendered an octave higher; by shutting a third part, a fifth higher, &c. There are not wanting, however, doubts concerning this new theory, arising from the cartilaginous and bony, and consequently immoveable and inextensible, glottis of birds; from the certain production of more acute sounds, in whistling, from the mere contraction of the lips; from the example of women, in which the larynx is softer, but the voice more acute, than in men; from experiments, which shew that more acute sounds are produced by bringing the ligaments of the glottis nearer into contact with each other; and from the total absence of machinery for stretching the ligaments, and drawing the thyroid cartiJage forwards from the annular one. But since it appears from experiments, that the tension of the ligaments suffices for producing acute sounds, without the contraction of the glottis, it is probable that difference of tension in the glottis contributes more than a difference of its diameter to the diversity of voice. Singing is produced when the voice, modulated through various degrees of acuteness and gravity, is expelled through the larynx, while vibrating and suspended between contrary powers, which chiefly distinguishes it from speech. It is a laborious action, on account of the perpetual action of the muscles poising the larynx; and it increases the animal heat, because acute tones require a contracted glottis, which retards the exspiration, and at the same time a great deal of air, to give them strength, and, therefore, deep inspirations are necessary. It tends very much to dry the windpipe, from the accelerated passage of the air; and renders a great deal of mucus necessary, which is the reason why there are such numbers of mucous receptacles in the larynx, amongst which Haller suspects the ventricles before described ought to be numbered. Speech is performed when the larynx is at rest, in tones differing but little in acuteness and gravity, by variously modifying the voice by the organs of the mouth. Sonorous speech has variations both in the tone, and modifications of the voice by the organs of the mouth. All speech is reducible to the pronunciation of letters, which differ in various nations, although they agree in the greatest number over the whole world. Of these some are called vowels, which are expressed by the mere emission of the voice through the mouth: other consonants, which are formed by a collision of the tongue against some part of the mouth, lips, or teeth. VOICED. a. (from the noun.) Furnished with a voice (Denhum). VOID. a. (vuide, French.) 1. Empty; vacant (Shakspeare). 2. Vain; ineffectual; null; vacated (Swift). 3. Unsupplied; unoccupied (Camden). 4. Wanting; unfurnish ed; empty (Whitgift). 5. Unsubstantial; unreal (Pope). VOID. s. (from the adjective.) An emply space; vacuum; vacancy (Pope). To VOID. v. a. (from the adjective; vuider, French.) 1. To quit; to leave empty (Shakspeare). 2. To emit; to pour out (Wilkins). 3. To emit as excrement (Bacon). 4. To vacate; to nullify; to annul (Clarendon). To VOID. v. n. 1. To be emitted (Wiseman). 2. To receive what is emitted (Shaks.). VOIDABLE. a. (from void.) Such as may be annulled (Ayliffe). VOIDANCE. s. (from void.) 1. The act of emptying. 2. Ejection from a benefice. VOIDER. s. (from void.) A basket in which broken meat is carried from the table (Cleaveland). VOIDNESS. s. (from void.) 1. Empti ness; vacuity. 2. Nullity; inefficacy. 3. Want of substantiality (Hakewill). VOIGTLAND, a territory of Upper Saxony, one of the four circles of the marquisate of Misnia; bounded on the E. by Bohemia, on the N. by the duchy of Altenburg, and on the W. by Thuringia and Franconia. Plawen is the capital. VOIGTSBERG, a town and citadel of Upper Saxony, belonging to the elector of Saxony, 18 miles S.S.W. of Zurickau. VOITURE. s. (French.) Carriage (Arbuthnot). VOLANT. a. (volans, Latin; volant, Fr.) 1. Flying; passing through the air (Wilkins). 2. Nimble; active (Philips). Fly VOLATILE. a. (volatilis, Latin.) ing; passing through the air (Bacon), 2. (volatile, French.) Having the power to pass off by spontaneous evaporation (Milton). 3. Lively; fickle; changeable of mind; full of spirit; airy (Swift). VOLATILE ALKALI, in mineralogy. See NATRUM. VOLATILE. S. (volatile, French.) A winged animal (Brown). VOLATILENESS. VOLATILITY. S. (volatilité, French; from volatile.) 1. The qua lity of flying away by evaporation; not fixity (Bacon). 2. Mutability of mind; airiness ; liveliness. VOLATILIZATION, in chemistry, vapo rization, or the conversion of a solid or fluid into a vapour or volatile aura, by the of agency caloric. Substances are said to be permanently elastic, volatile, or fixed. The permanently elastic fluids or gasses are those which cannot be condensed into a fluid or solid form, by any abstraction of caloric we are capable of producing. Fixed substances, on the contrary, are those which cannot be rendered volatile, or converted into vapour, by any increase of temperature. The pressure of the atmosphere has a very considerable effect in varying the degree at which substances become volatile, that are not naturally so. Some solids, unless subjected to very great pressure, are at once converted into vapour, though most of them pass through the intermediate state of fluidity, VOLATILIZE. v. a. (volatiliser, French.) To make volatile; to subtilize to the highest degree (Newton). VOLCANIC. a. Appertaining to volcanos; resulting from volcanos. VOLCANIC SAND, in mineralogy, a species of puzzolana. See the article PUTEOLANA. VOLCANIC SCHORL, in mineralogy. See SCORLUS. VOLCANIC FORMATIONS, in mineralogy, the fifth or uppermost of the Wernerian classification. In the article GEOLOGY we have observed, that M. Werner has arranged all the various kinds of rocks that enter into the solid surface under five separate divisions, to which he has given the naine of formations, according to what he supposes to be their more ordinary situation in regard to each other, as lying lowest, more superficial, or uppermost. The volcanic formations, however, are of two kinds or subdivisions, false and true. The former consist of minerals altered to a volcanic appearance, in consequence of the combustion of large beds of coal in their neighbourhood. The substances which are chiefly altered by this means are porcelain, jasper, earths, slag, burnt clay, coluinnar clay-iron stone, and haps polishing slate. per The real volcanic minerals consist of those which have been thrown out of the crater of a volcano, and are of three descriptions. First, ejected stones and ashes; secondly, different kinds of lava; and, thirdly, the matter of muddy eruptions. The stony ejections are those which are always thrown from the summit of the volcano: they accumulate and form the crater, which is a funnel-shaped hollow. Mineralogists have enumerated among ejected stones: I. Granular limestone, which is said to contain tremolite, pistacite, olivine, augite, Vesuvian, melanite, sommite, and hornblende; 2. Granite; 3. Mica-slate; 4. Green-stone; and, 5. Sand-stone. Lava consists of two sub species; viz. slag-lava and foam-lava: these do not extend far, having in general flowed, in streams of considerable height, into hollows, and gradually consolidated during its course. Matter of muddy eruptions comprehends volcanic-tuff, which is composed sometimes of ashes, sometimes of vesicular lava, and probably some particular chemical formations. See VOLCANO. VOLCANO: (from Vulcanus, Lat. the god of fire.) A burning mountain, hollow below, and communicating, perhaps, with cavities still deeper than its own, from which it is supplied with fire, and ignited materials, which it usually throws up, after uncertain intervals, through one or more external apertures or spiracles. Volcanos constitute, without doubt, the most striking and formidable geognostic phænomenon which nature has presented to our view. They are not, indeed, so destructive to the lives of the buman race as earthquakes; but they offer to the eye something much more terrific. Their number is very considerable, nearly two hundred having been reckoned by different writers. There is an immense range of them running from north to south on the continent of America, and occupying the summits of many of the Andes, as well as of the Mexican and Californian ridges. There also a considerable number that spread along the eastern coast of Asia, and sprinkle the Indian islands. Iceland alone contains eight volcanos. One of the loftiest is the Peak of Tenerif, though at present less frequent in its eruptions than many others. Several indeed of those that may perhaps be regarded as the most ancient appear to have spent themselves altogether; while others have been rising, even to our own days, as though it were to supply their place. Among the latter we have a very interesting account, in the Philosophical Transactions for 1708, of a volcano that burst out, for the first time, in the Archipelago, near the island of Erini, in the beginning of May in the preceding year, raising, at the same time, a new island out of the bosom of the deep. Similar eruptions, succeeded by similar islands, have occurred in various instances, in the group of the Azores, and the Sicilian seas; and captain Tillard, of his majesty's sloop Sabrina, has given a very valuable description, in the Phil. Trans. for 1812, of a like phenomenon, which took place no longer ago than June, 1811, in the vicinity of St. Michael's: the island then thrown up having been happily called by him Sabrina, after the name of his own ship. The two volcanos with which we are best acquainted are those of Etna and Vesuvius. The former has been burning as far back as the records of European history go. We have an account of an eruption during the expedition of the Argonauts, which took place at least twelve centuries before the commencement of the Christian era. The following dates of the remarkable eruptions of this volcano, to the middle of the seventeenth century, are taken from an article in the Philosophical Transactions for 1669. 476 years before Christ, Mentioned by Thucydides. During the reign of 40 years after Christ. Caligula. 812 years after Christ. Charlemagne. During the reign of 1284, 1329, 1444, 1536, 1633, 1650. The two writers who have chiefly signalized themselves upon the phænomena of this and the volcanos in the neighbourhood are sir William Hamilton and the abbé Spallanzani. To the former we are chiefly indebted for their history and effects, and to the latter for their possible causes and geognosy. It is from these celebrated writers that we shall deduce the remainder of this article, which we shall divide into two parts. History and Effects of Volcanos. Volcanos are peculiar to no climates, and have no necessary connection with any other mountains, but seem to have some with the sea, being generally in its neighbourhood; they frequently throw out matters which belong to the sea, as the relics of fishes, sea-weed, and sometimes sea-water itself. Sir William Hamilton observes in the Phil. Trans. for 1776, that "the operations of Vesuvius are very capricious and uncertain, except that the smoke increases considerably and constantly when the sea is agitated, and the wind blows from that quarter." Volcanic mountains are of all heights; some, as that of Tanna, so low as 450 feet; Vesuvius is 3600 feet high; and Etna, 11000. They in general form lofty spires; and the volcano itself is |