Page:Encyclopædia Britannica, Ninth Edition, v. 9.djvu/497

FORTIFICATION 465 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 employ ing electricity, and this is now as a rule employed in regular mining operations. Experience lias shown how little real injury the explosion of fougasses do 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 ob stacle 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 con nection 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 5) 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 GO 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 GOO 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 for tress 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 lands, 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 Diirer, and has adopted from him the system of flank ing defence, which depends on casemated galleries, and caponnieres 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 Rene, 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 1 1 quarto volumes, with 165 large plates, a work which must be considered the source from which all the modern " inven tions " 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 pro vided with casemated galleries, a second or advanced ditch, places of arms in front of the re-entering angles, a covered- way, and a glacis. The Polygonal System may, however, be considered as springing directly from Diirer s work of the same name, only in this system the simple earthen ramparts of Diirer are replaced by a combination of casemated towers, casemated galleries, and earthen couvre faces. In Diirer 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 caponniere. In forts which formed a triangle or square Montalembert was rich in resources, though the massive casemated tower, case- mated galleries, and earthen couvre-faces were the essential elements of all. In France, the views of Montalembert have never been received with enthusiasm, though Cher bourg 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 develop ment 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 Diirer may not have entered into the question, Montalembert s Systems, founded upon some of Diirer 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. - 59