the top of, or projecting towers at certain intervals along, the walls of fortresses, that from thence the besieged might get a view of and be able to annoy the enemy, when at the latest and most critical period of the siege the latter should have gained the otherwise undefended ground. The walls of Messene, built by Epaminondas (Paus. iv. 31), which were all of stone, and furnished with battlements and towers, were reckoned by Pausanias among the best specimens of Grecian fortification.

From the accounts given by antient writers of their fortified places, and particularly from the precepts of Vitruvius (Architectura, lib. i. cap. 5), we learn that the projecting towers were sometimes square or polygonal, but generally circular, and that their distance from each other along the walls was regulated by the range of the weapons employed in the defence. In the fortifications of cities this distance seems to have varied from 80 to 100 paces, according to local circumstances, and the power of annoying the enemy by the arrows and javelins discharged from the towers; but, from the greater distance at which modern arms will take effect, the bastions, measuring from the vertices of their projecting angles, are now generally, and agreeably to the rules of Vauban, placed at 360 yards from each other. It was a maxim with the antient engineers that the projecting quoins of walls were detrimental to the defence, from the facility with which they might be destroyed by the batteringram; and it is on this account that Vitruvius recommends the towers to be circular, or to have faces forming with each othor obtuse angles. These towers were placed indifferently at the angles, or at any part on the line of the inclosing rampart in the latter case, when they were of a square form, one side was parallel to the length of the rampart, and in the former, one face was almost always perpendicular to a line bisecting the angle between two adjacent sides of the polygon surrounding the town; that is, to what would be now called the capital of the bastion. It must have frequently happened, therefore, that this face was nearly unseen from any other part of the rampart, and that the enemy made his assault against it in order to avoid, as much as possible, being exposed to annoyance from the defenders of the neighbouring works. It is true that the smallness of the towers rendered it impossible for the enemy to be wholly concealed at their front; but the desire of entirely depriving the enemy of the benefit arising from the undefended nature of that ground probably induced engineers to dispose the faces of their towers like those of a modern bastion, so that two of them might form a projecting angle, whose vertex was on the capital.

There is no reason to believe that any material change took place in the manner of constructing the towers of fortresses during all the long period in which the antient arms were employed; but it is easy to conceive that the invention of fire-arms would render it necessary to enlarge the tower for the purpose of receiving the guns, and to increase the thickness of the rampart, that it might be able as well to resist the concussion produced by the discharge of the ordnance placed upon it, as the shock of the enemy's artillery when fired against it. On this account, also, the ramparts were constructed of earth, and their exterior surface was formed at such an inclination to the ground as would enable it to stand unsupported, except where it became necessary to prevent an escalade; in which case a facing of stone, brick, or timber was made sufficiently high and steep to create a serious impediment to any attempt of that nature. An opinion that the bastions are the weakest parts of a fortress remained in force, however, long after the modern artillery was introduced in sieges. On this account they were at first made very small, when compared with the extent of the wall between them; and the line of each face, when produced towards the town, was made to intersect that wall, in order that the fire from the part intercepted between this produced line and the flank of the next bastion might cooperate with that made from the latter in defending the ditch in front of the former bastion. But when the ramparts of a town were found to disappear almost instantly under the weight of shot discharged from large ordnance, it became necessary to employ ordnance of corresponding size on the walls; and the dimensions of the bastions were finally augmented to those at present assigned. The lengths of the faces vary from 100 to 120 yards, and the flanks are usually about 50 yards long; but the magnitude of the projecting angle in front, called the salient or flanked angle, to distinguish it from the angles formed by the faces and

flanks which are denominated shoulder angles, evidently depends upon the kind of polygon on which the enceinte is constructed. Each face of a bastion, if produced towards the town, now falls at the interior extremity of the flank of the collateral bastion, so that the defence of a bastion depends wholly upon the fires from those on its right and left.

It is to Italy that we must look for the invention of the modern bastion: the wars which raged in that country from the commencement of the twelfth century, and which were more systematically conducted there than in any other part of Europe, gave rise to this, as well as to many other inventions for military purposes. The precise date of its first formation is quite unknown; but if we omit the improbable story related by Folard, that the Turkish commander, Achmet Pacha, caused bastions to be constructed about Otranto, when he took that place in 1480, we may observe that it is spoken of under the name of Balvardo, as an improvement of great importance in the military art, by Tartaglia, in his Quesiti ed inventi diversi, which was published in 1546; and in the same work is given a plan of the fortifications of Turin, which exhibits a bastion at each of the four angles of the rampart. Both Vasari, in his Lives of the Architects, and Maffei, in his Verona Illustrata, ascribe the invention to San Micheli of Verona: one of the bastions of this city has on it the date 1527, and its construction is still ascribed to that engineer, who, in fact, was about that time employed in the erection or repair of several of the fortresses in Italy. From the word Balvardo, denoting a stronghold, the earliest French engineers gave to this work the appellation of Boulevard; and such is its designation in the treatise of Errard, which was published in 1594. The term Bastion appears to have been taken from the Italian writers, for Maggi, in his treatise Della Fortificatione delle Citta, applies the term Bastioni to redoubts constructed of earth; and, according to Pere Daniel, the French subsequently gave to such works the name of Bastilles, or Bastides. Froissart also uses these terms in speaking of the forts executed during the siege of Ventadour by the Duc de Berri, under Charles VI. It should be remarked, however, that Errard applies the name of Bastion indifferently to works in the situation of those now so called, and to those to which the name of Ravelin is generally given; and doubtless it denoted originally any work of earth constructed on the exterior of one more antient.

It appears that it had been the practice from the earliest times to form a rampart, or bank of earth, in front of the walls of fortresses, in order to secure the latter from the destructive effects of the ram; and it is easy to conceive that, by forming such a bank in front of the old towers of a place, so as to connect those previously existing in front of the adjacent curtains, the work would assume a figure like that of a modern bastion; and indeed would very much resemble one of the detached bastions in what is called the second system of Vauban; the original tower of the fortress occupying the place of the interior bastion of that system, and constituting a sort of retrenchment to the new work. The construction was proposed in 1584 by Castriotto, seemingly as if it had been his own idea; but probably he meant only to recommend the adoption of a kind of work which must have been then a novelty.

The Italian engineers, immediately after the invention of the bastion system of fortification, became celebrated for their skill in military architecture, and they seem to have been extensively employed in the construction or repair of fortresses beyond the Alps: one of the first of their labours in the north of Europe was the fortification of Landreci, with bastions, for Francis I.; and the like works were executed about New Hesdin, on the frontiers of Artois, for Charles V. In 1568, the Duke of Alva employed Pacciotto in the construction of the citadel of Antwerp, a regular fortress, whose bastions still exist within those subsequently erected at that place; and, during the reign of Elizabeth, Genebella was brought from Flanders to this country in order to superintend the formation of a bastioned enceinte about the antient castle of Carisbrook, in the Isle of Wight.

Albert Durer, the celebrated engraver, proposed, in 1527, to fortify places with circular towers only, like those of the antients, but of larger dimensions; and in most of the plans published during the sixteenth century by Italian engineers, there appears to be a union of the old and new methods: for the angles of the polygons are furnished with round towers, and these are protected exteriorly by bastions.

Fig. 1. The line A B represents one side of the polygon | on the left of the capital, B E, represents what is called a supposed to inclose the town fortified. The semicircular hollow, and that on the right a solid bastion. An imaginary work at A is half a round tower; and A C is part of the line from f to g is the gorge, and the rampart, ef, is the curtain, or connecting wall between two such towers, ac- curtain joining the right flank of one bastion to the left of cording to the antient manner of fortifying places; a c re- the next. The space, F G E, is the main ditch; and H presents a sort of fausse braye, or elevation of earth pro- and K are respectively the positions of a counter and enfitecting the antient walls of a place. D represents half a lading battery which might be constructed by the enemy to bastion constructed at the angle, A, of the polygon, accord- silence the fires from the triple flank of D. The outworks, ing to the method of the first Italian and French engineers, P, G, Q, R, S, [TENAILLE, CAPONNIERE, RAVELIN, Cowith an orillon and triple flank. The pentagonal figure VERED-WAY, and GLACIS] will be described under those about B is the plan of a modern bastion, of which the part words.

Fig. 3.

T

In fig. 3, V represents the plan of a detached bastion; T is a tower bastion at an angle of the polygon which surrounds the place.

(Vitruvius, De Architectura; Maggi, Della Fortificatione delle Citta, Venetia, 1584; Errard, La Fortification réduite en art, Par. 1600; De Ville, L'Ingénieur Parfait, Par. 1672; Vauban, Euvres Militaires, par Foissac, Par. 1795; Belidor, La Science de l'Ingénieur, Par. 1729; Fritach, L'Architecture Militaire, Par. 1668; Cormontaigne, Euvres Posthumes, Par. 1809; Montalembert, La Fortification Perpendiculaire, Par. 1776-98; Bousmard, Essai Général de Fortification, Par. 1814; St. Paul, Traité Complet de Fortification, Par. 1806; Savart, Cours Elémentaire de Fortification, Par. 1830; Mandar, De l'Architecture des Forteresses, Par. 1801; Dufour, De la Fortification Permanente, Genève, 1822; Carnot, De la Défense des Places Fortes, Par. 1812; Col. Pasley, Course of Elementary Fortification, Lond. 1822; Malortie, Permanent Fortification, Lond. 1821; Capt. Straith, A Treatise on Fortification, Croydon, 1833.)

BAT. [See CHEIROPTERA.]

BATA'RA (Zoology), D'Azara's name for the Bushshrikes, forming the genus Thamnophilus of Vieillot. A very good account of these birds, which appear to have been found between the northern and southern points of Canada and Paraguay, will be found in the Memoirs of Dr. Such and Mr. Swainson, published in the Zoological Journal. The latter zoologist considers the typical group to consist of the species with long tails; and of this division, Thamnophilus Vigorsii, Such (Vanga striata, Quoy and Gaimard), may be taken as an illustration.

Dr. Such states this to be the largest species yet known, and gives thirteen inches as the length of the body. The bill is black and very much compressed. In the male (which is the sex here figured) the back, wings, and tail are black, broadly banded with fulvous, and the under part of

Leach thus describes it from a specimen in the British Museum: Black; back and belly ash-coloured; the former anteriorly spotted with white; quills of the wings externally, and the tips of those of the tail, white; under part of the body ash-colour, of which colour the back partakes in a considerable degree.

BATATAS, the Malayan name of a convolvulaceous plant, the root much eaten in the south of Europe before the cultivation of the potato, which both became a substitute for it and appropriated its name. It has generally been considered a species of convolvulus; but Professor Choisy, in his recent classification, has erected it and a few others into a peculiar genus, distinguished by having an ovary with four cells, in each of which there is only one seed.

[Batatas.]

also occur in inscriptions), the name of the antient inhabitants of South Holland, and some adjacent parts. The Batavi were a Germanic tribe of the race of the Catti, who, some time before the age of Cæsar, left their native district, and settled on the banks of the Vahalis, the present Waal, a branch of the Lower Rhine. They occupied the district between the Vahalis and the Mosa above their junction, and also the island formed by the northern arm of the Rhine (or Rhine of Leyden), the Vahalis and Mosa after their junction, and the ocean; which island now constitutes part of the province of South Holland. Cæsar (De Bell. Gall. iv. 10), who mentions their country by the name of Insula Batavorum, appears to consider it as belonging to Germany, and not to Gaul; the limits of Belgic Gaul on that side being placed at the southern branch of the Rhine, or Waal, after its junction with the Mosa, or Maas. They seem to have occupied also a small portion on the banks of the Rhine, and not within the island. Cæsar did not carry the war into the country of the Batavi. Under Augustus the Batavi became allies of the Romans. Drusus, the brother of Tiberius, resided for a time among them, and dug a canal, Fossa Drusiana, which connected the Rhine with the modern Yssel. Besides the Batavi there was another people on the same island, probably in its north-western extremity, called by the Roman historians Canninefates. They were of the same origin as the Batavi (Tacitus, Hist. iv. 15.), but not so numerous, and their name became gradually lost in that of the larger tribe.

The chief place of the Canninefates was Lugdunum Batavorum, now Leyden; and that of the Batavi was Batayodurum, afterwards called Noviomagus, and now Nymegen. This is Mannert's opinion, though others have placed Batavodurum at Duurstede, and made it a different place from Noviomagus. The other towns of the Batavi were Ârenacum, generally supposed to be Arnheim, but placed by others near Werthuysen; Carvo, on the northern branch of the Rhine, probably near Arnheim; Grinnes, near the junction of the Waal with the Maas; Trajectum, the modern Utrecht; and Forum Hadriani, in the western part of the island near the sea. The name of the Batavi can be traced even now in that of Betuwe, which is a district of the antient Batavorum Insula, between the Rhine, the Waal, and the Lek. [See BETUWE.] Beyond the northern branch of the Rhine, and between that and the Flevium, or Yssel, in the province now called North Holland, were the Frisii and the Frisiaboni, tribes belonging to the great Frisian stock which inhabited the land north-east of the Yssei. Pliny places two other tribes, the Sturii and the Marsucii, on the islands off the western coast at the mouth of the Mosa, which islands now form part of Zealand.

After the death of Galba, the army of the Rhine having proclaimed Vitellius, and followed him on his way to Italy, the Batavi took the opportunity of rising against the Romans, whose alliance had become very burthensome to them. Claudius Civilis, a man belonging to one of their principal families, though bearing a Latin name, acted as their leader. At one time the insurrection seems to have spread among the neighbouring tribes of Germans as well as of Belgian Gauls, but the speedy return of the legions suppressed the movement. Civilis resisted for a time, but the Batavi were at last subdued. Still it would appear that they obtained The only species of any general interest is the Batatas conditions, for we find them afterwards restored to their foredulis, the Convolvulus Batatas of authors. This plant, mer state of free allies of Rome. (Mannert, Geschichte der originally found wild in the woods of the Malayan archipe- alten Deutschen.) It appears, however, that subsequently, lago, has been gradually dispersed over all the warmer parts under the reigns of Trajan and Hadrian, the Romans had of the world, where it is still an object of culture for the sake completely established their dominion over the Batavi; for we of its roots, which, when roasted or boiled, are mealy, sweet, find in the Antoniue Itinerary and the Peutinger Table, two and wholesome, but slightly laxative. It is a perennial Roman roads across the country, one from Lugdunum eastplant, with long creeping stems, leaves variously lobed and ward to Trajectum, and following the course of the northern angled, and pale purple flowers about an inch long. It is Rhine to its separation from the Vahalis, and another from impatient of cold, and consequently unfit for cultivation in Lugdunum southward across the island to the Mosa, and the northern parts of the world; but it is a productive agri- then eastward along the bank of that river and the Vahalis cultural plant in many warm countries. It is partially cul- to Noviomagus. We also find places named after the tivated in the south of Spain and of France, whence its roots emperors, such as Forum Hadriani, and fortified camps, are sent to the markets of Madrid and Paris, where they are such as Castra Batava, which some, however, suppose to held as a delicacy. They, however, have the great fault of have been the same as Batavodurum. (See Mannert, Geokeeping badly, being very apt to become mouldy and to de-graphie der Griechen und Römer.) There was another cay, unless extraordinary pains are taken to preserve them dry. Sometimes they are raised in the hothouses of curious persons in this country, by planting them in rich soil in a bark-bed, when plenty of roots weighing from one to two pounds are easily obtained.

place in Upper Germany, or, more properly, in Noricum, called also Castra Batava, near the confluence of the Inn and the Danube, which was colonized by Batavi, apparently in conformity with the policy which led the Romans to transplant their subjects and allies from their homes to foreign countries. [See ARMY.] The Batavi were em