ravelins, &c. on the front attacked; which, after a stated period of the siege, are calculated to throw incessantly such a profusion of metal, stones, &c. as to cause what the theory presumes, inevitable destruction to the opposing forces. Twelve and fifteen-inch mortars, capable of discharging at once 600 four-ounce balls, are the terrific chimera thus gaping to prey on approaching legions. According to the calcul ation advanced in the theory, the proportion of the area of the trenches is to the portion occupied by the troops, workmen, &c. as 180 to 1; and hence it is inferred that, out of every 180 balls, &c. which fell within the trenches, one would kill or disable a man. The power or force attributed to these balls, &c. is according to that which a body of any ponderous kind is supposed to acquire in falling from a given height; which, agreeably to the established laws of falling bodies in vacuo, is proportional to the time: so that, whatever force a body acquires in one second, it will acquire double that force in two seconds, three times the same in three seconds, and so on: thus gaining a constant acceleration of descent by a constant addition of force, till the descent becomes interrupted.

Now it is altogether the general application of this vertical firing, or the discharging into the air to a considerable degree of altitude the various kinds of projectiles, so that they may by a length of fall acquire a force sufficient to do execution, that constitutes the novel part of the scheme. After a few observations, then, on the manner in which the proposition is advanced and conducted, these two primary considerations may be examined; - first, whether the assertion of the theory will be accomplished in practically directing the purposed showers of iron, &c. on the lodgments of the besieging forces; and, secondly, whether, if well-directed, the force of the blow will be sufficient to produce the formidable conse quences imagined.

Such men as Bonaparte, accustomed to dictate peremptorily, cannot be expected to speak diffidently on what they, according to the course of reasoning which they apply, have conceived to be clearly and indisputably possible: especially if it be something devised by themselves in order to abet or accomplish a political object:- but, probably, it was more from a fallacious conviction than from design that Bonaparte sought to propagate "cette verité tranquillisante" (this consoling fact), that a profusion of vertical fire in defence of her numerous fortresses would effectually secure France from the incursions of enemies. If the problem for effecting these metallic rains should appear on inspection to be feasible, it is by no means self-evident: indeed, its solution certainly in

volves

volves many intermediate considerations and intricate. consequences, which seem either to have been overlooked or artfully omitted; such arguments only having been adduced as were judged to favour a deduction suitable to the accomplishment of the object. The time at which, and the circumstances under which, the "verité tranquillisante" or cardiac potion was administered, being observed, many particulars apparently authorize a belief that policy was the first object of the publication. The remote expedition against Russia was contemplated; and it was a master-piece of state-prudence that France, in the event of disasters, should be taught to possess implicit confidence in her many powerful bulwarks. Motives of this political import would justify an author in eluding those considerations which might throw doubt on his inferences; and the more he could disguise his arguments, so that the semblance of truth might be craftily assumed in the end, the more competently would he have managed his question, and his merit be more intitled to esteem: but ought not arrogance on such occasions to be laid aside? When, on any subject of debate, an overweening superiority is affected, and a deficiency in the mode of decision is manifest, very little respect can be paid. Even in Bonaparte, as an author, and if correct in his allegations, presumption is scarcely pardonable, and in Carnot certainly much less: but, as before intimated, it is very probable that Bonaparte, if the assurance with which he seemed buoyed up under such signal discomfitures be a criterion, faithfully believed the efficacy of the defence proposed to be instituted; and, if so, he was evidently not aware of any indiscretion in the extraordinary enterprizes which he attempted. Confident in the impregnability of France itself, the stake which he was risking for the chance of extending his dominion would seem to him nothing, in comparison with the consequences which would result from winning his game. Thus might he have been the infatuated convert of a delusive doctrine, and the ruined dupe of his own bigotry; for that the success of his depending scheme rested more on vague and fallacious conceits than on consequences derived from sound principles will, in the sequel, become unquestionable.

With regard to the manner in which the new system was publicly received, whether its conclusions were deduced from infallible rules or from chimerical sources, the authority of such celebrated men as Carnot and his master was enough to give it an imposing claim to attention. Indeed, the extended circulation and numerous reprints of the book (already mentioned) are some testimony of the devotion paid to it abroad; and, not having found that any foreign engineer has disputed its merits, we may fairly conclude that it has acquired general appro

approbation. Independently of the dogmatic importance with which these eminent authorities accost their readers, and proclaim their opinions, the bare idea of such destructive cataracts as the theory provides has apparently had its influence on the judgment of many, from whom a more grave consideration of the means designed for its accomplishment might have been expected. Indeed, in so plausible a manner is the project introduced, that it is not very easy to believe it to be impracticable without the means of convincing the understanding by experimental facts. Who, from a slight or abstract view, could conceive it possible for forces to escape from beneath such tremendous and incessant showers of metal, stone, &c., as are thus positively threatened? Who, on such a view, would not be easily seduced to believe that annihilation must inevitably await all those whose hostile temerity might lead them within the reach of these devastating volcanoes?

"Ac veluti lentis Cyclopes fulmina massis

Cum properant,

gemit impositis incudibus Etna." (VIRG. Georg. iv. 170.) Thus have opinions seemingly been formed on the efficacy of the plan; and from the prevalence of such opinions, so credulously entertained, does it appear to have acquired such extraordinary sanction.

--

This extensive and eminent suffrage, awarded to the professed novelty, having attracted the attention of Sir Howard Douglas, he determined to enter into a full and radical investigation of the principles on which the system had been constituted; and finding from a most able analysis that they were frail, he has completely succeeded in reversing the character of the new theory. From irrefragable proofs, — from facts founded on a variety of carefully conducted experiments, - it appears certain that such a scheme of defence, if practised against a regular attack, will totally fail; and even that a fortress, defended according to the principles and rules prescribed by the nouvelle manière, must surrender sooner than if the system taught by Vauban and other eminent masters of the old school were still followed.

We may now try to ascertain how far the proposed engines are capable of pouring their charges into the enemy's trenches, which is certainly a primary consideration. M. Carnot, be it recollected, computes that out of every 180 balls, &c. which fall within the trenches, one will kill or disable a man: but, in the shape of a calculation, nothing could be more illusive. That eminent mathematician evasively omitted to state how many balls &c. out of any charge, or out of any given quantity, he expects to fall in the trenches; so that the proportion

of

of waste to effective balls cannot be obtained from any report or conjecture which he has offered. From the results, however, of numerous experiments, Sir Howard Douglas considers that one ball out of every 720 is about the proportion on which we might calculate as thus far effective. • Several rounds,' he says, were fired at an elevation of 45° before a surface composed of deal targets and wadmill-cloth tilts, of 774 square feet, was hit at all; and at 75° the spread of the balls was nearly four times as great as at 45°. Now we must reckon a length of 45 feet of a parallel (trench), 17 feet wide, to give a surface upon the horizontal plane equal to that of the targets and tilts; and when we find that these were SELDOM hit and NEVER injured, we can have no hesitation in pronouncing judgment upon the uncertainty and impotency of M. Carnot's vertical fire.' Here, then, are unquestionable facts to prove that the firing in this manner is very greatly at random, and much more ineffectual than the theory conjectures.

In M. Carnot's estimation of the momentum or effect of his various charges, it is plain, from Sir Howard's exposition, that the resistance of the air to the descending bodies, which is very considerable, has not been taken into the account. Charged with cubical blocks of iron, the range of mortars and such engines is much more irregular and uncertain than when loaded with balls; and charges of stones fired in this manner must,' says Sir Howard, be extremely uncertain, and scatter so much that a very small proportion would fall in the trench aimed at; whilst a great many, falling short, will undoubtedly take effect upon the defendants in the advanced works over which the discharge is made.

The dispersion of a charge of stones thrown from a mortar or pierrier is much greater than any person, who has not witnessed it, would imagine. No two stones of any charge fall within many feet of each other; and the dispersion is much greater in a longitudinal (the line of discharge) than in a transverse direction. This is also the case, though in a less degree, with projectiles of the same size, shape, and specific gravity.'-' But, lest all this should be received as matter of opinion, instead of fact established by experience, I give the results of some very careful experiments, made purposely to ascertain the precise effects of those natures of vertical fire which M. Carnot proposes to adopt as the principal means of defence.'

A perusal of the whole of Sir H. Douglas's work being requisite to convey a sufficient idea of its merits, in the connection of the facts and arguments by which its conclusions are wrought, we deem it unnecessary to insert here the results of his course of experiments, which cannot fail to prove satisfactory to every person who examines them.

After having detailed his experimental facts, Sir H. applies

them

them to a plan, or specimen of a fortress, &c. according to the nouvelle manière, copied from Carnot, and thus continues:

It appears that neither the third parallel (the trench nearest to the walls of the fortress) nor the couronnement of the glacis (the top of the sloping bank which rangeth from the exterior parapet towards the field) are within the reach of stones forced to the utmost from pierriers in the casemated battery; (the chief batteries before mentioned constructed in the gorge of each bastion;) and the horizontal area of all those parts of the attack which come within its influence is so small, compared with the vast magnitude of the elliptical surface upon which the stones fall, it may be relied upon that not one stone in one thousand would take effect upon the besiegers.'-Moreover, At the rate of discharge which M. Carnot mentions, it would require a provision of nearly 1,500,000 pounds of iron (about 700 tons) for the seven 'casements of ONE batterie de gorge.

We consider these brief citations as quite sufficient to evince the great uncertainty in the aim of projectiles cast from the proposed engines, and consequently the useless expenditure of ammunition; as also that, from the main batteries, the most powerful of these ordnance will not project stones beyond the outer works of defence. It might, however, be submitted that Sir Howard seems to have considerably overrated the chance of striking the besiegers, when he allows that one ball in 720, and one stone in 1000, might be so far effectual.

It must have been already anticipated by the general reader, from what has been said of bodies descending in vacuo, that a considerable diminution of force will occur in their falling through the atmosphere: yet it seems that neither Napoleon nor his war-minister was sufficiently aware of the consequence of this effect of nature; which, if they had, would certainly have weakened their confidence in the proposed measure. On this point Sir Howard Douglas, after having noticed some very inapplicable arguments in the new theory, thus remarks:

• M. Carnot's idea, then, of the effect of this pluie de balles is founded upon the velocities which he supposes they will acquire in accelerated descent from the vertex of a very elevated curve;this is manifestly the principle upon which he tries to establish his theory. But the fact is, there can be no acceleration beyond a certain limit, which, with small balls, is very much less than is generally imagined.'- From the vertex of the curve, where all the vertical motion is lost, the ball begins to descend by an urging force which is nearly constant; viz. its own weight. This force would produce equal increments of velocity in equal times in vacuo; but in air the descent of the ball being more and more resisted as the velocity accelerates, the urging force will, at a certain velocity, be opposed by an equal resistance of the air, after

which