a trench, sunk some feet in the earth, from the charge and pit to the place of ignition, in order to secure it from accidents as well as from the enemy's observation (see fig. 26, page 429, in which is also represented the mode whereby the fire is applied by what may be called the fire-box, the end of the trough and powder-hose being introduced into it). As for the thorough fulfilment of the object of a military mine the explosion should be "immediate," it is requisite to employ a contrivance for producing instantaneous ignition. This can be most readily and perfectly effected by employing electricity, and this is now as a rule employed in regular mining operations.

Experience has shown how little real injury the explosion of fougasses does to an assailant; but, as the moral effect of them is a degree of hesitation or irresolution often greater than that produced by musketry fire, and as they are easily extemporized, the fougasse may still be considered an obstacle of some value to the defence. Loaded shells packed in a case may be substituted for the ordinary charge, the case being formed with a horizontal partition, and the fuses of the shells placed on the lower portion of the case, passing through holes in the partition, so as to be brought into connection with the firing-hose in the upper portion of the case. Another form is the stone fougasse, which is probably the most effectual of all. It is constructed thus. A conical pit is made in the earth about 5 or 6 feet deep, the axis being directed towards the enemy at an angle of 45° with the plane of construction, and at the bottom a charge of 50 lb of powder is placed in a well-tarred box. Over the box, and perpendicular to the axis of the cone, is fixed a lid, on which as a platform are packed either stones or broken bricks, which, on explosion, are scattered over a space of about 60 by 70 yards. It should be laid down as a rule that facilities for discharging mines ought to be in every fortress, whether electric apparatus be used for the purpose, or openings be prepared in the works through which the powder-hose may be carried.

The last great modification proposed by Choumara is the extension of the exterior side, and the value of this can no longer be matter of doubt, now that the effective range of musketry has so much increased. The length of the line of defence may now be safely and advantageously fixed at between 400 and 600 yards, so that musketry and artillery can co-operate together efficiently. Chasseloup had, indeed, proposed to make his exterior side about 700 yards long, and he was no mere speculative engineer, for he had fortified with great skill Alessandria in Piedmont; but it must be borne in mind that no greater distance should be allowed for musketry than is compatible with distinct vision and a correct appreciation of distance; and further that the men intended to use the rifle in a fortress ought to be well trained for that object. The Gatling gun may in fitting positions be used with effect instead of musketry; it delivers a continuous stream of bullets at the rate of 400 per minute. The value of one Gatling is equal to 22 rifles, and nearly equal to two 9-pounders, and though it has a range of 1200 yards, it produces its best effect at short distances. In the defence of ditches its defect is that it cannot break or overturn scaling ladders.

GERMAN SYSTEM OF DEFENCE.

Having traced the history of bastioned defence to the high state of perfection it attained, a summary of other systems will complete the subject. It has been shown that no sooner had the Italians invented the Bastioned System of defence than it found in every country persons who devoted themselves to the improvement of its details, -in France, Errard, Pagan, and Vauban; in the Nether'ands, Freitag and Coehorn; and in Germany, Speckle, who was at least equal to any of the others. Germany however justly it prided itself on Speckle, has gone back to Dürer, and has adopted from him the system of flank

ing defence, which depends on casemated galleries, and caponnières or casemated works placed across the ditches. Yet, notwithstanding this, it is remarkable that the Ger

mans have taken much of their works from a French officer the celebrated Marc René, Marquis de Montalembert, who in 1776 published his celebrated work, Perpendicular Fortification, or an Essay on Several Methods of Fortifying a straight line, a triangle, a square, and all polygons of any number of sides, giving to their defence a perpendicular direc tion; also, Methods of improving Existing Defences and rendering them much stronger; also, Redoubts, Forts, and Field Intrenchments, of a New Construction, in 11 quarto volumes, with 165 large plates, a work which must be considered the source from which all the modern "inventions" in this branch of Fortification have been derived. Referring back to earlier German writers, it appears that Rimpler in 1673 proposed a system which is a combination of bastions with tenailles, and that Landsberg in 1712 proposed a purely tenaille system; but both these adhere to earthen ramparts and parapets, the first with revetments, the second without them, and their systems are little more than extensions of Field Fortification. But Montalembert, in his Tenaille System, replaces the simple revetment at the re-entering angles with casemated works in two stages, thus affording direct fire, both of artillery and musketry, for the defence of the ditches and faces of the redans, the remaining portion of the trace being occupied by an earthen couvre-face work, with a detached loopholed gallery in front of it, evidently the prototype of Carnot's detached revetment. The re-entering casemates are calculated to hold 24 guns in two tiers. Behind the couvre-face is the body of the place of the redan, being also fronted by a casemated gallery, and separated from the couvre-face by an inner wet-ditch. In this system, then, the defence by musketry as well as by artillery is from two levels, the upper at a moderate height above the bottom of the ditch, and not, as in the old Italian systems, at the high level of the crest of the parapet. At the gorge of each redan is placed a formidable casemated tower; whilst in front of the main ditch there is a general couvre-face provided with casemated galleries, a second or advanced ditch, places of arms in front of the re-entering angles, a coveredway, and a glacis.

The Polygonal System may, however, be considered as springing directly from Dürer's work of the same name, only in this system the simple earthen ramparts of Dürer are replaced by a combination of casemated towers, casemated galleries, and earthen couvre faces. In Dürer's polygon the sides were straight or unbroken, but in Montalembert's the centre was thrown back and formed into an Italian bastioned trace, the faces flanking the faces of the caponnière. In forts which formed a triangle or square Montalembert was rich in resources, though the massive casemated tower, casemated galleries, and earthen couvre-faces were the essential elements of all. In France, the views of Montalembert have never been received with enthusiasm, though Cherbourg is fortified in conformity to them, and it was even alleged that the corps du genie was indisposed to receive instruction from an officer of another arm; but it is more reasonable to suppose that the cherished name of Vauban has induced its officers to direct their attention rather to the improvement of the Bastioned System, which they have certainly carried to perfection, than to the development of a system depending on such different principles. In Germany, on the contrary, Speckle is less known than Vauban, and though probably a thought of Dürer may not have entered into the question, Montalembert's Systems, founded upon some of Dürer's principles, have been adopted, and may be studied in the works of defence of Coblentz. In all such works masonry defences or casemated buildings IX.

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assume a character of the highest importance, but it should not be forgotten that masonry can never resist the effects of a concentrated fire of heavy guns, and can be considered safe only when protected by earthen masks or couvre-faces. The Maximilian towers of the defences of Lintz are no longer approved by modern engineers, and in closing the harbour of Sebastopol against approach by sinking a large portion of their own fleet, the Russians exhibited their distrust of masonry defences when opposed to ships. And this distrust is not to be wondered at, when it is remembered that, to bring the guns forward enough to afford them lateral training, the walls of casemated batteries must be cut into, and greatly weakened. This great defect of masonry defences, and the evils of smoke in close casemates, are well known to engineers. In the earliest periods of Italian fortification, the necessity of increasing the active power of the flanks beyond that afforded by their length was strongly felt; and retired flanks, rising one above the other, were adopted, as well as casemated flanks admitting two or more tiers of guns, thus obtaining, as in Montalembert's System, a greater number of guns by extending the battery vertically. At first sight this appears an obvious mode of acquiring a superiority over the attack, in which the batteries can only be extended laterally, but in practice the retired flanks were soon found to be untenable, while the front flanks were complete shell-traps, and the casemates were practically useless from the difficulty of clearing the smoke from them. The systems of Montalembert partake of the same defects; and however imposing the appearance of several successive tiers of guns may be, it should be remembered that, covered by a mask, they can only be partially used when the enemy is at a considerable distance, and that exposed to view they can be easily destroyed at 2500 yards by the guns of attack of the calibres now in use. Several writers have proposed systems based upon principles similar to those of Montalembert, but it is perhaps sufficient here to mention the work of Don Jose Herrera Garcia (Teoria Analytica de la Fortificacion Permanente), as it is unquestionably the most remarkable development of the tower system of defence. Garcia proposes several successive lines of massive casemated buildings or towers, of an egg-shape, connected together with casemated curtains. The towers are surmounted by parapets, which at the ends next the enemy are broken into a series of smaller curves, and are retired or independent of the exterior wall or scarp. As each of these towers is defensible of itself, the work of forcing a way through three lines of them would be most formidable, but the expense of such a system would be enormous.

The system of the Swedish general Virgin belongs to the bastioned systems, but it is mentioned here in contrast to Garcia's, as it disperses in the defences separate bastioned forts, of a form somewhat approaching to Rimpler's, and covered by outworks so arranged as to secure the inner works from injury until the enemy has effected his lodg ment upon them. These forts are surrounded on all sides by ditches, and connected together by secure communications. Ingenious as Virgin's system is, it is manifest that though the loss of one fort would not ensure the fall of the others, it would at least render all the interior space inclosed by the line of forts untenable, and place the town, the arsenal, or other public buildings, at the mercy of the besiegers. This may be said of all detached forts, and it must be again laid down as a maxim that the ultimate value of such forts, as a means of securing an important object, depends on an inner line of defence of a nature to resist any sudden attack or coup-de-main. Detached forts may be, for the purpose of keeping an enemy at a distance, more effectual than a simple continuous line, but they cease to be of use if an enemy can pass them and attack

a defective interior line behind, incapable of resisting a coup-de-main.

It has been well stated by the French translator of Zastrow, that the reduction of a place may be considered as a certain amount of work to be performed, the magnitude of which depends on various elements, amongst which the disposition and nature of the works constitute the most important; and that the attack has to perform this work in a certain time, and with certains means, amongst which the principal elements are the quantity of heavy artillery, and the nature of the ground over which the approaches must be carried. When, therefore, it is said that a work fortified on Vauban's first system would fall on the twentyeighth day,-on Cormontaigne's, with a cavalier entrenchment in the bastion, on the thirty-first, it must be remembered that this implies the possibility of complete investment, and of steadily advancing the approaches over soil easily worked by the sapper; but that if the investment be incomplete, if the ground be rocky, and every inch have to be gained by hard and incessant toil, protracting the time during which the sapper is uncovered, and therefore greatly adding to the daily losses in the trenches, such periods may readily be extended to twice or three times their ordinary length.

INTRENCHED CAMPS.

It would not be proper to leave the subject without a brief description of intrenched camps, especially as they have an important bearing upon the defence of capitals, with which this article closes.

An intrenched camp is a position, prepared beforehand, in which an inferior army rests in security from the attack of a superior army, and from which it may operate upon the communications of such superior army, or in which a beaten army takes refuge for the purpose of reorganization. The position selected for an intrenched camp is usually around the capital, or around an important city, or on an important line of communication. The position should, therefore, contain sufficient space to receive the army for which it is constructed, to contain ample supplies of all kinds, and to keep an enemy beyond bombarding distance not only from the city but from the camping grounds within it. An intrenched camp should consist of a chain of independent forts, with, wherever practicable, a strong inner work; the forts should be as large as possible, and disposed in a right or slightly convex line. No fort should have undue prominence over the others, as such a fort would be a source of weakness, inasmuch as it might be attacked by itself, and being further removed from the centre of defensive operations would be more difficult to succour. The camp should be traversed by free and easy communications; and if it have an interior work, that work should command the whole of the interior. It should also possess facilities for passing rapidly from the defensive to the offensive, and sufficient interior space for the execution of such manœuvres as are necessary for the defence of the position.

FORTIFICATION OF CAPITALS.

Whether capitals, as capitals, should be fortified has given rise to much difference of opinion; but all authorities are agreed that the capitals of highly centralized countries must be fortified. In such countries the principal resources of the state, both public and private, are collected in the capital; in it is placed the centre of government, and from it administration and organization radiate. Such a capital is truly the heart of the nation; a deadly blow to it stops the national circulation, and national paralysis may and will probably follow. Take, for

example, England, perhaps the most highly centralized of countries. Can it be doubted that an enemy in possession of London could exact what terms he pleased? Upon this point the commissioners appointed to consider the defences of the United Kingdom say,- "There can be no doubt that the main object of an enemy invading the country would be to push for the capital, in the hope that, if he succeeded in obtaining command of it, such a disaster would result in our buying him off upon any terms he might think it expedient to exact." This was written in 1860, but within eleven years its general truthfulness was thoroughly established by the fall of Paris, when the exactions of the Germans were only limited by the ability of the French to comply with them. It is then scarcely too much to say that the fall of London would result in the downfall of England. Speaking of the general confusion and ruin which the presence of a hostile army on British soil must produce, Lord Overstone said: "The occupation of London by an invading army! . . I cannot contemplate or trace to its consequences such a supposition." And he might well say so; not England only, but the cause of civilization throughout the world would be shattered by such an occupation.

At a time when capitals were by no means the national centres which they have since become, owing to the develop ment of the means of locomotion, and to the discoveries of electrical science, Napoleon said that a great capital is the native place of the flower of the nation, the central point of public opinion, and the general depôt; and he added that it is the greatest of absurdities to leave so important a place destitute of immediate defence.

How then should a capital be fortified? The answer is, that it should be so fortified that it may be safe from bombardment and from blackade, and that its defences may be beyond the control of its inhabitants.

These objects may be attained by two methods,-first by constructing a circle of detached forts round the capital, and at such a distance in advance of it as shall render investment impossible, or, secondly, by forming a cordon of intrenched camps far in advance of the capital, making at the same time such arrangements as shall facilitate the rapid concentration of troops in any of them.

With respect to these two methods there is much difference of opinion, and eminent military authorities may be cited in support of one or the other according to the bias of the writer. Nevertheless it may be safely asserted that the value of either is dependent upon the number and quality of the troops available for its service. If the troops be few, or insufficiently trained and poor in quality, then it would be proper to have recourse to a system of detached forts round and not far in advance of the capital, and so disposed that they may, in a measure at least, be manned by local auxiliary levies. If, on the other hand, the troops be fully equipped, thoroughly trained and disciplined, with high power of manoeuvring, then, even though inferior in number, it may be advisable to have recourse to a cordon of intrenched camps.

Generally, if circumstances admit of its adoption, the second method is the better, especially if the camps are disposed at such intervals that an enemy in force cannot pass between them, and at such distance from the capital that, if driven out of them, there is still time left to fall back and take up some inner position upon which to deliver a decisive battle. The capital, though well covered by the camps, would take no part in the active defence, and would not be attacked after the fall of one of them, while the occupants of the camps could fight with no apprehension of the populace rising in their rear, a danger to be apprehended from the most patient of people, as they become pinched by the privations and miseries of a siege.

In practice it will almost always happen that a combination of the two methods will be adopted; but whatever method be adopted it will generally be inadvisable to surround the capital, more especially if large, with a close enceinte. If, however, it have such an enceinte, the works of which the enceinte is composed should be provided with strong interior defence. In all large cities there is a considerable cosmopolitan and vagrant element, possessed of no property, and having no interest in the maintenance of order, whose contact with the soldiery may be attended with deplorable results, inasmuch as it must tend to lessen the bands of discipline, to destroy the habits of obedience, and to weaken those feelings of devotion and self-restraint which are more than ever necessary under the privations of a close siege.

Against this view it may be urged that the enceinte constructed round Paris in 1840 prevented its falling into the hands of the Prussians after the battle of Chatillon. This may be true; but in estimating the value of this enceinte it should be borne in mind that 236,000 Prussians were sufficient to shut up in it, and eventually reduce by famine, a garrison of 300,000 men, and it is certain that the absence of interior defences in that enceinte permitted a mere handful of communists to make themselves masters of Paris and its fortifications, and to force back the regular troops upon Versailles. Generally, however, the rapid growth of the population in very large cities precludes a close enceinte. Indeed, the enormous extent of very large capitals, and the very long range of present artillery, render the fortification of them so costly that, in elaborating any scheme for their defence, cost must enter largely into calculation, and must materially modify theoretical and scientific conclusions.

But however elaborately the capital may be fortified, the full effect of the expenditure upon its fortifications is not obtained unless other strong places are formed in appropriate positions in relation to it; for if the capital only be fortified, defence will cease with its fall. It is asserted upon the authority of official documents that the French would not have yielded to the conditions exacted by the conquerors of Paris in 1871, if there had remained to them strong defensive positions such as Orleans, Tours, and Bourges, upon which the armies, poor in quality as they were, of Chanzy, Faidherbe, and Bourbaki could have operated. In fact, if the capital only be fortified, the object of invasion will be limited to it, and the task of the invader will be much simplified, for he will have little fear of his communications, and will be able to make his circle of investment of such strength as seems best to him. And when once the investment is completed, it is matter of great difficulty for the inclosed army, even if superior in numbers, to break out. Its best chance of breaking out is during the first days of the investment, particularly at the period when the enemy commences to extend himself round the circle of investment, and in so doing presents his flank to it. After the investment is complete, the inclosed army is in a bad position for delivering an attack, as it must advance and deploy under concentric fire playing upon it in front and in flank. The difficulties of such an attack are exemplified in the French attack during the siege of Paris upon the 5th German corps between St Cloud and Buzenval, when 84,000 French attacking from an interior position were defeated with a loss of 6000 men by 20,000 Germans with a loss of only 646.

The advantage of other strong places was shown when 180,000 Germans were detained for a time before Metz. But Metz and Strasburg were so far from Paris that they had scarcely any relation to it. Moreover, they lay close to the frontier; and as here there were no intermediate strong places they were rapidly isolated, and when they fell into the invader's hands proved of great service to him.