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conferred upon his name a high degree of celebrity. His profound mathematical knowledge, and the important use that Bonaparte made of his abilities, impressed professional men with a very exalted opinion of his system of fortification, and proposed plan of defence. Sir Howard Douglas, an officer of intelligence and scientific acquirements, has favoured the public with observations on Carnot's plans of defence, and clearly demonstrated that vertical fire, upon which the French engineer relies with so much confidence, as the basis of the defence of a fortified place, is by no means entitled to any very great degree of estimation in repelling the attack of besiegers.
Let us, first, bestow a few words on Carnot's system of fortification and vertical fire, and afterwards examine the observations of the British engineer. in looking at the plan of Carnot's fortification, there seems to be very little -deviation from the established rules of engineering, as laid down in the works •of the celebrated Vauban. The revetement of his polygon consists of bastions and curtains, of saliant and re-entering angles—ditch and covert-ways, and the usual out-works found in the plans^ of that great engineer. In some minor particulars, Carnot has attempted to improve the defence of Vauban's bastion, by a revAteuient across the gorge; but that is not a new improvement, as similar propositions have been suggested by several engineers.
In the construction of out-works to cover the body of the place, there seems to be uo very material alteration promised—the counter-guards, and demilunes, are not much improved; and the double covert-way, and additional revetement to protect the bastions, are little calculated to retard the approach of the besiegers. Indeed, M. Carnot seems to be sensible of the inutility of his out-works, as he appears to rely principally for the defence of his fortress, upon vigorous sallies and continued vertical fire.
With, regard to sallies, let it be observed, that a garrison must be very strong to defend extensive out-works, and to make numerous and determined sallies. Establishing extensive places of defence and garrisons of great numerical strength, is acting in direct contradiction to the acknowledged principles of fortification; as the great intention in erecting a fortress, is to enable the state to hold an important po
MoNTHhY Mag. No. 362.
sition with a small number of men* M. Carnot's fortified place is, therefofein direct opposition to this fundamental principle, as his out-works are so extensive as to require a strong body of troops for their defence; and the construction of the works is so inefficient as to demand constant and vigorous sallies, to repel the besiegers. With regard to the efficacy of sallies, prnfes-^ sional men are by no means agreed. The most effectual one of modern times was that made by the garrison of Gibraltar, under the direction of its veteran governor, the late Lord Heathfield, when the whole of the Spanish batteries and approaches were taken and destroyed.
The other branch of M. Carnot's defence, vertical fire, Sir H. Douglas has, by the most satisfactory experiments, proved to be of no importance whatever, as precision in the direction,andeffect of vertical projectiles, cannot be attained. The discharge of stones would be useless, and the operation of iron balls by no means so formidable as to impeda approaches of the assailants. The defence,-therefore, of M. Carnot's works must still depend upon the usual arms and means employed in military watfare.
Having made these observations on M. Carnot's fortification and plan of defence, let us enquire h3W it happens that so celebrated an engineer has not been able to devise a system of defence better calculated to resist ricochet and enfilading batteries? Can there be no efficacious deviation from right lines and saliant angles, by which the artillery upon the works of the fortress may be protected? Traverses are clumsy expedients, and occupy too great a portion of the ramparts—and could not such an engineer as Carnot prepare a better remedy? It seems he has not— and the only additional defence which he has adopted for his bastion is the casemated battery be'aind its gorge. This battery can only be mounted with mortars—cannon would be useless, unless the battery was considerably elevated above the guns upon the bastion, and in that case they would be exposed to the fire of the artillery of the besiegers, who, from the nature of attack and defence, always possess a superiority of fire.
Let us now turn to Sir H. Douglas, who has unquestionably shewn the best manner in which M. Carnot's fortification may b« attacked and taken. But 3 S there there is nothing new in the plan of operation which he has proposed, and it is to be exceedingly regretted, that so acute and intelligent an engineer, has not fully examined, and remarked with more exactness upon M.Carnot's system for the construction of a fortified place. Is it acknowledged that wehavearrived at perfection in fortification, and that no further improvement can be made in the art of defence? The late General Jarry informed his pupils that he had a new system of fortification to propose, but he did not shew it to any of the officers who were under his tuition; and from what is since known, it does not appear that he had any new system to offer, otherwise it would hare been adopted by some of bur engineers.
The destructive effect of enfilade and ricochet batteries, is still felt in sieges, and no effectual remedy has yet been prepared. Will Sir. H. Douglas, who seems so well qualified to discuss scientific subjects—or will Colonel Jones, whose history of the sieges in the Peninsula shews him to be an officer of talents and information, favour us with a more perfect system of fortification than what we possess—or, at least, inform us what effectual remedy can be employed against the operation of enfilade and ricochet batteries, as traverses seem to be the only defence in use at present.
It is in time of peace that the principles of war should be discussed and examined. When hostilities commence, professional men are too much employed to enter deeply into military speculations. Let it be recollected, that in several sieges in the Peninsula, great faults were Committed: the right of our i approaches at Badajoz was so ill covered as to be open to an enfilade; and at Burgos and St. Sebastian, there were several instances of a palpable want of knowledge manifested in the attack of fortified places.
A British Officer.
For the Monthly Magazine.
LETTERS/-om the SOUTH of ITALY, by
a recent Traveller.
(Continued from page 295.)
Catania, Aug. 27, 1819.
WE set out at three o'clock, P.M. from this city, and proceeding slow'iy on my mule, I ruminated on the description which I am about fo give yoV of the most celebrated of vol
canoes, of which you have already heard so much, that I have, decided simply to relate to you what oamc under my own observation. We began our march in frightful roads, amidst rocks of lava which cover the 'first part of the route. Our mules, habituated fo these rough passes, never once stumbled; but an accident happening tojmine embarrassed me greatly. I felt my foot wet, and one side of my pantaloons was covered with blood; I alighted, and perceived that my mule had been recently hurt. With a handkerchief and thong we bound up the wound, and continued our journey in a road covered with lava, but bordered with superb Indian fig trees, (this fruit, which is despised in America, is an article of great consumption in Sicily,) ordinary fig trees, and enormous olives: eveiy where else this tree appeared to me paltry, and of a difficult vegetation; but here it grows to admiration. After proceeding five or six miles, we passed through the village of Gravelina; where I was assailed by nearly the whole population demanding charity. The number of poor which you meet with in Sicily and Italy, is sufficient to harden the heart of the traveller, who cannot be expected to supply the wants of such idle mendicants, who languish on a land, the fruitful soil of which affords all that is necessary for subsistence. Some miles further we perceived, and afterwards passed through, another village called Masca-Luscia: it contains two churches; one of which; nearly destroyed by an earthquake, was never very remarkable, and the other is only rendered so, by a steeple fantastically decorated with stones of various colours. We arrived, in fine, at the last village, that of Nicolosi, which appeared poorer than all the rest; this was surely in former times, the Town of Etna, where the inhabitants of Catania took refuge, on the arrival of the Greeks: the environs abound in olive trees and vineyards, which produce excellent wine. All this part was covered with ashes by the eruption of Monte Rosso, a secondary volcano which formed itself at thetimeof the last eruption. Monte Rosso is one of those mountains by which Etna is surrounded. It appears that when an eruption takes place, the lava making its way on the flanks of the mountains, pierces the ground in the place which offers the least resistance, and there forms a swelling, which it. afterwards consolidates
consolidates by flowing from above. In this village we found the guide, or, as be is called, the Pilot of Ettia. After some conversation, he engaged to ascend for three piastres, about twelve shillings and sixpence. From thence to the convent, where we were to rest our leasts, we had no more than a mile to go, which we performed in coasting along Monte Rosso, whose summit was gilded by the sun, and behind which it had already set, when we arrived. This mountain is several miles in cir- , cumference. I profited by the last light of the sky, in order to sketch a view of the convent, which although of the common extent, is nevertheless very picturesque. Built against a small hill, long since become cold, and covered with woods, it seems sheltered from the A destructive effects of the volcano; from the other side, between superb fir trees, you perceive the sea, the plains of Catania and Syracuse. You are received into the convent nearly in the same manner as -you would be at an inn ; the best situated room for the view is reserved for strangers; but is very indifferently furnished. We were four hours in coming from Catania, which is, notwithstanding, only a distance of twelve miles. Being provided with a fowl, &c. I supped pretty well, slept in my cloak, and weset out at half past nine by moon light, the guide, servant, and myself, on our mules, the muledriver always on foot. We first entered into an immense torrent of lava; the uncertain, glimmerings of the moon gave an extraordinary aspect to the huge masses by which I was surrounded. I forgot to tell you, that in this convent, which is very convenient for the traveller visiting Etna, as be there dines and rests himself, you also put on winter clothing; in fact, that season was drawing near when we quitted the monastery. You might have seen me then on the 21st of August, dressed nearly in the same manner as in England in the month of December. Sooa after, long shadows scattered here and there, and a trembling of the leaves, announced the approach to the forest of oaks, which formerly encircled Etna to the height of several miles; but which an immense torrent of lava had cruelly ravaged. The light of the moon, the huge and broken rocks, the great oaks, whose vegetation surprises the beholder, in the midst of lavas, tlie silence of my guides, interrupted only by the rust
ling of the leaves, and by the trampling of our mules, every thing led me to reflection. How can we reconcile the evident primitiveness of Etna with what Moses informs us of the creation of the world? It is true, he does not ■ say that God created the world in infancy; and if He made Adam at the age of thirty years, He might also well create Etna with an open crater, and its flanks covered with lava.
While journeying along, I asked my guide if it was true, as I had read, that the mountain subsisted all kinds of game and wild beasts: he begged me not to be afraid: I repeated the question to him, and received the same reply, he being still persuaded that the fear of encountering ferocious animals caused me to speak in that manner. I should, notwithstanding, be led to believe that the mountain, considering its extent and gradual temperature, might well support them; but it seems to me that Mr. Brydone gave too wide a scope to his imagination, when he described Etna as a general botanic garden, an almost universal menagerie. As for the rest, I had not the pleasure of seeing any of these animals, and we arrived without molestation, at the extremity of their domain, the forest, which may be about six miles in width. We then entered into the most fantastical lavas; they have more of a slope, andr the crevices which form there, as , soon as they become cold, acquire more extent, and present a more rent appearance. It was one o'clock, and already the wind blew piercingly cold.
I was sorry not to have brought a thermometer, but I had not been able to find one for sale, either at Messina or at Catania. As for a barometer, it would have been almost useless to me; the custom of calculating the elevation with this instrument, is extremely blameable. Some have found the elevation of Etna to be twelve thousand feet, and others twenty-four thousand. Cassini reckons ten fathoms for the falling line of the mercury, by adding one to the first ten, two to the second, &c., but he has never surely made the experiment of his method on very high mountains, where the air is rarefied in a much more rapid progression. Etna might be measured trigonometrically, for it descends as far as the sea, the shore being taken for the base. We may even have an approaching idea of its 'elevation by tile time wbjch the
sun's light lakes in descending from its summit to the sea.*
Having arrived near a mass of snow which filled one of the narrow passes of the mountain, a summit which looked black in the sky, made me believe that I was at the end of the journey; au old tower which I took for the Torre del Filotofo, confirmed me in my error. I soon after perceived another .summit covered with a whitish smoke; I asked if it was much higher than the other: my guide affirmed that it was, and he was in the rigKt, for it seemed to me to surpass the first in the whole height
the substance which it drags along, are sufficiently hard to prevent their melting, and that they are like the basalt, detached from the immense vaults which during many ages supported this natural forge. The sky began to adorn itself in the east, and we perceived the house called Let Anglais. You have generally the key of this hut; but not having sent a shilling, with my request, to tlie person it belonged to, or rather to his domestic, we entered into the stable, where we kindled the charcoal which we had brought, and I can assure you, that I experienced there a
of Vesuvius. The road became more pleasure which I had nol for a long time ,.„;t»,l „„,i n.„ „„,.i;, ;,.,„,,„,.... i... enjoyed, that of being cold and feeling
the beneficent heat of the fire. After a light breakfast I directed my steps towards the place where, according to custom, the .curious go to behold the rising of (he sun.
There is no sight in the world which can equal this: the point of Calabria, the sea which separates it from Sicily, the mountains of Southern Italy, even the clouds which covered them, seemed to be at your feet.
The horizon was in a blaze: a globe of fire escaped from the floods, it was the sun appearing in the midst of the fog: it was of a greyish red, and its horizontal diameter was much greater than the perpendicular. The colour became more vivid; a rapid flash of lightning which glided along the surface of the sea, announces the presence
united, and the acclivity gentler, but the wind was very violent, and the cold as sharp as it is with you in winter. We coasted along a torrent of blaek lava, the more singular, as its elevation was from eight to (en feet, and perpendicular likea wall, which clearly proved to me, that this matter, in flowing, is not in perfect fusion ; as a great part of
* In returning from Alexandria to Marseilles in the month of March, I saw Etna covered with snow. A calm having lasted spme hours, I profited by it to take the height of this mountain. With the aid of a mariner's compass, I perceived that the Cape Sparti-Vento, in Calabria, reached us by the N.N.E., and Cape Passaro, in Sicily, by the S.W.; I was then sore of the point where I found myself on the chart. (We made use on board of the French charts of the Mediterranean, which are very
good.) This point beiug at a distance of °f thestarofday ; its diameter enlarged, sixty miles from the foot of the axis of aad it rose in the heavens. I profited
Etna, I measured at that time the angle which the summit of the mountain made with the horizon; it was found to be six degrees; which gave me a rectangular triangle of which I knew a side and the three angles, the one right, the other of six degrees, and the third of eighty-four degrees. The base being of sixty miles, there remained for me only to make the following proportion:
Sin. 84° : 66 miles :: Sin. 6° : Ui The result is found to be, for the axis side of Etna, four miles and twenty-four eightyfourths, above four miles and a quarter, or about twenty thousand, four hundred feet for the total height. This measure is not perhaps perfectly correct, but, at least, it approximates very near to it. If this height appears surprising, we ought to
by the moment in which the shadows still lengthened on the plains, to elimb up the last summit, at a distance of two miles.
I do not exactly know how it can he explained, why the sun appears lengthened in the fog, if it is not by the pressure which each bed of the latter produces on the one under it; the stars appeared brilliant and numerous, and the moon was small but bright. I have already more than once remarked this effect in the most elevated places, which I attribute to the rarefaction of the air diverging a little the luminous rays.
The mule-driver remaining with our beasts, I bent my steps towards the last summit, which covered witha light
consider that other great mountains have white smoke,'seemed to move away
never been measured but with the barometer, and that Mr. Bry done was surprised to see the mercury here, descending nearly two inches lower than on the summit of the Alps.
from the impatient traveller. We walked nearly a mile on an almost horizontal lava, or (o speak more correctly, on striated scoriae, or dross, which made a cracking noise under our feet,
INTERIOR OF THE
and soon after on a large swamp of snow, where we found a large round stone, three feet in diameter, of the species of those called volcanic balls, which the mountain throws up in great eruptions; but it is only a grain of metal in comparison with the volcano, which ejected it from its bosom. In fine, we mounted the last cone which supports the crater; the ashes and the stones slipping under our feet. The cold was excessive, but exercise kept us warm; 1 quitted my cloak, and rolling up in it some pieces of lava, I left it on the mountain. My guide, in order tore- ■ pose himself, invited me at every moment to enjoy the view whicli presented itself. At last we arrived on the borders of the crater; but the wind was so violent, that I could scarcely cast a glance over it. I was thrown down, and had it not been for my ciceroni, I might have rolled lo the foot of the declivity which had given us so much trouble to ascend. Fastened and lying down on the ridge of the crater, I considered it at my ease, and braved the fury of /Eolus and Vulcan.
It is a vast aperture having four summits of different heights, rather more than a mile in width, and on account of its inequalities, I should think it about four in circumference. It is divided into two craters, by a cone rising from its centre, and which forms a
CRATER OF ETNA.
crater itself, the slope of which is not very rapid. The antient aperture is united to this cone by a gentle declivity where has probably been formed within a recent period, a small crater, a partial volcano, a perfect truncated cone, from whence issues a great quantity of smoke. The general aspect of the crater is much less dreary than that of Vesuvius; the substances surrounding it are not so black, but have rather the colour of potter's earth. It is now six years since Etna has made an eruption, but it has given concussions which have alarmed the inhabitants of Catania and overthrown some houses. I attribute its silence and its tranquillity, not to the extinction of the fires, for they still rage in its bosom, but to the great vacuum which must necessarily exist under this enormous vault. The whole of the mountain being formed only by what it has seized and driven out of the bowels of the earth, we might reasonably think that an interior vacuum, perhaps equal to the half of the exterior mass, must exist; at least that it is nt>t filled with water as some.persons have believed. However this may be, it appears that in great eruptions, all the cones,all the partial volcanoes formed in the crater, are thrown to the outside; which must then make a frightful aperture by its extent and profundity. I dont know whether, when this