more of being superintendant of his extensive property in America, but this he declined, and accepted the place of teacher of the French, German, and natural history, in the academy of Warrington. This place, however, he left soon after, and returned to London, where he resided in very confined circumstances till the year 1772, when he was engaged to go out as naturalist with Captain Cook, who was then ready to proceed on his second voyage round the world. Forster, at this time, was forty-three years of age, and was accompanied by his son George, then seventeen. He returned to England in the year 1775, and soon after the University of Oxford conferred upon him the degree of Doctor of Laws. After his return, he publish ed, conjointly with his son, a botanical work in Latin, containing the characters of a number of new genera of plants, which had been discovered by them in the course of their circumnavigation. An account of the voyage having been published in English and German by young Forster, in which the father was supposed to have had a considerable share, though he had entered into an engagement not to publish any thing separately from the authorized narrative, they not only incurred the displeasure of government, but gave of fence to the principal friends by whom they had been patronised. This work abounded with reflections injurious to the government in whose service they had been, and unfavourable to the navigators who had conducted the expedition. They were therefore treated with so much cool. ness that they both determined to quit Eng land. Fortunately for Forster, after struggling some time with poverty and misfortunes in London, he was invited to Halle, in 1780, to be professor of natural history; he was also appointed inspector of the botanical garden; and as this office was connected with the faculty of medicine, he next year got the degree of Doctor of Medicine. The loss of his son George, who died at an early period of life, made a deep impression on Forster, whose health was already in a declining state; and in the spring of the year 1798, his case was so desperate, that he expressed himself as a dying man in a letter to his friend Harsten, dated Halle, April 14. He did not long survive this letter, dying on the 9th of December, 1793, at the age of sixty-nine years and some months. Forster is represented as a man of highly irritable and quarrelsome disposition, of which he is said to have given several in. stances during his voyage round the world; and which, added to a total want of prudence in common affairs, involved him, notwithstanding his talents, in perpetual diffi culties. The following character of him, by his friend the celebrated Kurt Sprengel, of Halle, exhibits him in a more favourable point of view:"To a knowledge of books, in all branches of science, seldom to be met with, he joined an uncommon fund of practical observations, of which he well knew how to avail himself. In natural history, in geography, both physical and moral, and in universal history, he was acquainted with a vast number of facts, of which he who draws his information from works only, has not even a distant idea. This assertion is proved in the most striking manner by his Observations made in a Voyage round the World.' Of this book it may be said, that no traveller ever gathered so rich a treasure on his tour. What person of any education can read and study this work, which is unparalleled in its kind, without discover. ing in it that species of instructive and pleasing information which most interests man, as such? The uncommon pains which Forster took in his literary compositions, and his conscientious accuracy in historical disquisitions, are best evinced by his 'History of Voyages and Discoveries in the North,' and likewise by his excellent archæ ological dissertation On the Byssus of the Ancients.' Researches such as these were his favourite employment, in which he was greatly assisted by his intimate acquaintance with the classics. Forster had a predilec tion for the sublime in natural history, and aimed at general views, rather than detail. His favourite author therefore was Buffon, whom he used to recommend as a pattern of style, especially in his Epoques de la Nature,' his Description of the Horse, Camel, &c.' He had enjoyed the friendship of that distinguished naturalist, and he likewise kept up an uninterrupted epistolary intercourse with Linnæus, till the death of the latter. Without being a stickler for the forms and ceremonies of any particular persuasion, he adored the Eternal Author of All, who exists in the great temple of nature, and venerated his wisdom and goodness with an ardour and a heart-felt conviction that, in his opinion, alone constituted the criterion of true religion. He held in utter contempt all those who, to gratify their passions, or imitate the prevailing fashion, made a jest of the most sacred and reputable feelings of mankind. His moral feelings were equally animated; he was attracted with irresistible force by whatever was true, good, or excellent. Great characters inspired him with an esteem which he sometimes expressed with incredible ardour." His works, besides those above mention. ed, are, for the most part, compilations and translations He was the author also of several papers published in the "Philosophical Transactions," the “ Memoirs of the Academy of Sciences" at Petersburgh, and those of other learned societies. FORSTERA, in botany, a genus of Gynandria Diandria class and order. Essential character: perianth double, outer inferior, three-leaved; inter superior, sixcleft; corolla tubular. There is but one species. FORT, in the military art, a small fortified place, environed on all sides with a moat, rampart, and parapet. Its use is to secure some high ground or the passage of a river, to make good an advantageous post, to defend the lines and quarters of a siege, &c. Forts are made of different figures and extents, according as the ground requires. Some are fortified with bastions, others with demi-bastions. Some again are in form of a square, others of a pentagon. A fort differs from a citadel, as this last is built to command some town. FORTIFICATION. During the early ages when the property of individuals was less valuable, or that, owing to the little progress made by mankind in the arts of despoliation and of seizing upon the possessions of their neighbours, the only fences in use were such as sufficed to restrain the depredations of wild beasts, and to prevent cattle, &c. from straying among the scattered patches of cultivation, or into the wildernesses. In proportion, how ever, as commerce, or communication with others, and the pleasures of society, induced men to build towns and to congregate more generally, the various passions inducing to the commission of that variety of trespasses, which have even, within our own time, increased rapidly, rendered it prudent for each individual to secure his own habitation from clandestine or open assault, and caused the little communities, which every where began to appear, to adopt general means for personal defence, and for the curb of whatever encroachments might be attempted by others in their vicinity. At a time when the great simplicity of manners gave a limit to the ambition even of the most aspiring, and when science was yet in the womb of time, we may reasonably conclude, that the means of control and of resistance, then in use, were neither costly, laborious, nor very effectual. The details furnished in scripture prove incontestibly, that even the circumvallations used at their date were inadequate to the purposes of security and duration. In fact, the events that shone conspicuous in those times were, with very few exceptions, pitched battles in the open plain, atnbuscades, and treasonable conspiracies! Nor do we find in the more recent histories of Rome, of Greece, of Asia, or of other parts then holding any rank in the military world, much to support the opinion of the ancients having knowledge of fortification. The few places that made any resistance appear to have been principally maintained by the personal prowess of their defenders. Their walls were, indeed, sometimes of great moment, as we see in the instance of Troy; which, if existing in the eighteenth century, would probably capitulate at the first summons. It was not to be expected that where the powers of demolition were insignificant, the means of resistance would be extended beyond the quantum absolutely necessary. The catapulta, the battering ram, the tower, and such devices, were opposed by heavy masses of stone, or of other adequate materials, on which the besieged mounted to repel the assault. The various contrivances whereby those machines received additional vigour, and the necessity that arose for opposing to their progress more resistance than could be accumulated immediately in their front, (of the tower in particular) first gave rise to the introduction of projections from the even line of the wall, whereby the besiegers could be annoyed laterally, as well as immediately front to front. Still the engineer confined himself to small projections, generally semicircular, which, for the most part, appear to have been added to the old walls, impending like our modern balcony windows. In the sequel, these towers were built the same as the other parts of the circumvallation, and, like the modern bastion, rested on the terra firma. It however seems doubtful, whether the former mode was not the best, considering every circumstance attendant upon the ancient mode of assault, and the nature of their weapons. The invention of gunpowder does not appear to have made any important change for several years, nor indeed until heavy artillery formed a part of the assailants' means, as may be proved by an examination of the remaining castles, towers, keeps, &c. the dates may be traced beyond the middle of the fourteenth century. Such were the solidity and the hardness of many ancient buildings, that the stone shots, originally used, produced a very slight effect; nor was it until iron balls were brought into use, that the powers of cannon were, in any measure, ascertained. That point being gained, the whole system of defence was necessarily made to conform to the destructive engines which now were added to the common practices of assault. The sword, buckler, lance, dart, javelin, sling, bow and arrow, lost their wonted estimation, and, dwindling into insignificance on the great scale, were reserved for individual contest, or for the lesser purposes of desultory warfare. The great object was to construct such stupendous bulwarks as might not only oppose the newly devised missiles, but, at the same time, support similar means of destroying the invading army. Hence arose the formation of ramparts, and, gradually, the necessity for deep ditches, and various outworks; whereby considerable delay and difficulty might be created. The fortifications of the fifteenth century, although to a certain extent new modelled, and made conformable to the neces sity imposed by the invention and use of cannon, nevertheless did not display any ingenuity in regard to mutual defence. That great principle was little understood, and the minutiae of the science remained, for a long time, miserably defective. Men of genius, at length, in part remedied the errors of the old school, and opened the way for that exactness of proportion, and for that systematic arrangement, which cha racterize the works of modern times. The impregnable fortresses to be seen in various parts of Europe, cannot fail to transmit the names of their several engineers to posterity; unhappily, not unaccompanied by those of the traitors and poltreons who, even since the commencement of the present century, have shamefully abandoned VOL. III. the posts of honour, and yielded to inferior powers. The immense armies now constantly brought into the field, and the heavy trains of artillery by which they are, in almost all cases, attended, occasion not only an adequate preparation for resistance, but the necessity for establishing lines of communication, of depots,;&c. all of which must be on the best construction for defence, containing safe lodgment for a sufficient garrison, together with ample and secure magazines for provisions and for stores. Hence the province of the engineer becomes peculiarly important; it comprizes various branches of information, and requires that readiness of computation, of discernment, and of appropriate resource, which rarely combine in the same individual. The merely planning in the closet, and the laying down on the soil such defences as may perhaps be void of fault, so far as relates to mutual support, and to the great work of procrastination, will avail nothing, if the other essentials are neglected; and even when they are not, the whole may be rendered abortive, and become contemptible, merely from a want of judgment in point of locality. Fortification is generally considered under two heads, i. e. natural and artificial. The former relates entirely to those invaluable situations which, being either completely inaccessible, or nearly so, require but few additions, and demand only such guards as may prevent surprise. For want of that precaution, some posts have been taken, which no army, however numerous and well provided, could have forced to capitulation. Perhaps of all the instances that could be adduced in regard to so fortunate a position as should defý assault, the fortress of Ootradroog, situated in the dominions of the late Tippoo Saheb, sultan of the Mysore, may be justly considered as the most worthy of being cited. It stands on a plain, no hill or eminence of any consideration being within several miles. It is, in fact, insulated, and consists of a solid rock, rising, on an average, about eight hundred feet above the adjacent level; its sides are nearly perpendicular throughout its whole circumference, which measures nearly a mile. The ascent into it is by stone steps, intermixed with occasional breaks for temporary ladders, the whole of which could be destroyed by the fall of a few large stones, always kept on the paraO pet for that purpose. Indeed the interior is lined with such, they being admirably suited to the defence of so peculiar a station. There is no want of cannon on the works, which are ample, and were formed under the direction of a French engineer; they have plenty of water; ample stores kept in immense excavations; and the mos secure lodgment for a numerous garrison. Yet, so soon as the fall of Bangalore was ascertained, this important and absolutely impregnable fortress, to which, perhaps, there exists not a counterpart, surrendered to two battalions of Bengal sepoys. It would be impossible to afford any instructions regarding those works which may be conjoined to natural defences, so as to render the whole complete; such must depend entirely on local circumstances, of which the skilful engineer will not fail to take advantage. Artificial fortification applies to every kind of defence, whether regular or irregular, pure or mixed; and has been divided by the most celebrated engineers into two distinct kinds, viz. offensive and defensive. The former relates principally to the various works used in attacks and sieges; the latter appertains to the more general purpose of securing towns, forming depots, commanding choice situations, defiles, &c. protecting harbours, and, in general, tending more to self-preservation, and to control, than to the annoyance of others, or to the extension of dominion. This important science is again subdivided into the permanent and the temporary: the former being with the view to endure the test of ages, while the latter is confined principally to operations in the field; and such works are, for the most part, abandoned so soon as the occasion for their construction may have subsided. Defensive fortification consists of three systems, each of which has its particular uses: 1. The little which is usually adopted in the construction of works, having four, or five sides, or citadels, various small, or detached ports, horn-works, crown-works, &c. where the exterior of the defences, that is, between the saliant angles of the two bastions does not exceed 350 yards. 2. The mean, which is of general use, and forms a very considerable portion of all regular fortifications, whose exterior sides of defence may be from 350 to about 400 yards. 5. The great, which is principally used where the exterior of the defences measures more than 380, and as far as 500 yards, or perhaps rather more; it is obvious, that such very extensive fronts, even in a hexagon, or figure of six sides, would enclose an immense area; consequently would require a moderate army to man the defences. Hence we generally find this system composing only part of the works; such as are on the borders of a lake, or of a marsh, or along the bank of a river; while the other sides are composed of the second or mean system. Such are the leading features and applications of the three systems, as settled by the celebrated Vauban, and adopted by the most distinguished professors of our own time. Occasional deviations have, however, been made in several instances, with the approbation of pre-eminent engineers; but, for the most part, such have been with the view of conforming to local necessity, and of effecting a saving, either of materials, where they were scarce, or to disbursement, where parsimony was an object. Anomalies of this description are not to be considered as data whereby to be guided; but it may be proper to study the practical effects of all innovations, however much they may be abstracted from received theories; for the most happy inventions generally experience much opposition, often, indeed, illiberal contempt, while in their infancy. This should not deter the man of genius from ushering his suggestions to the notice of the world; for although his inefficient measures may appear wild and eccentric, or eventually be ignominiously decried by those invincibles, who, having learnt to work "by line and rule,” neither will, nor can, correct their errors; yet there will never be wanting, in this enlightened age, persons who can both comprehend, and duly appreciate, the effusions of a vigorous and sensible innovator. We now come to the description of the several defences, as regulated by Vauban, and others of acknowledged skill, premising, that many opinions have started, and other proportions been recommended by men of first rate talents, who have each their advocates. What is now offered may be deemed a concentration of their various hypotheses, so far as they could be assimilated into one general system: to give all would occupy volumes. Fortifications may be considered as regu lar, when the enclosed area is of such a form, as can be inscribed in some regular figure; such as a triangle, a rectangle, a circle, or an ellipsis: observing that such figure should, in a manner, fit the town, &c. it is intended to protect. It is usual to divide the perimeter, or whole outline of the figure, when it is either of the two lat ter forms, into as many faces, or portions, as nay admit of suitable defences in either of the three systems already detailed. The number of faces must be regulated as well by the form, as by the extent of the figure. Small circles may be divided into five or six faces; moderately extensive ovals may have six also, while the more extensive circles and ovals will require an additional face or more, in order to reduce the exterior lines of defence within due bounds; so that every part of each face may be within musquet shot of those parts whereby it is flanked, or defended. Whenever this fundamental principle is disregarded, the plan will be proportionally weaker, according to the undue prolongation of the faces, and the consequent deficiency of mutual support. The several fronts of a fortification may be all dissimilar, both in their proportions and in their extent; as also in the number and construction of their several outworks; yet the whole cannot be termed irregular. Thus the two ends of a long oval may be constructed on the second, i. e. the mean system; while each of the two long sides may be upon the third, or great system. One end may have a horn-work; the other a crown-work; the lateral faces being strengthened with ravelines, lunettes, tenailles, or other works, all these are evidently regular members of a perfect whole, and when duly combined, according to the rules of art, form a complete and regular defence, founded on approved systems. When the number of faces has been adjusted and laid down, it is proper to decide whether the works are to be planned out wards, or inwards, from the line laid down. In the former case much space is gained by keeping all clear within that line, which by this means becomes the interior side: in the latter instance the line becomes the exterior side, all the works being raised within it, which considerably diminishes the area within them. It is to be remembered, that in laying down the plan of a fortification, the several lines, describing the outer part of each rampart, exhibit the situation of a semicircular projection of masonry, called the cordon, which is, with few exceptions, made at the top of their respective facings of stone, brick, &c. called revetements. The line thus following the direction of the cordon, as it proceeds along the works, is called the principal. A reference to fig. 1, Plate Fortification, will illustrate the foregoing description. The half of a hexagon, or polygon of six equal sides, is selected, as being the most appropriate to this occasion. The line A D, is the diameter of the circle; which circle having been divided into six equal parts, each equal to the radius, or semidiameter, A E, or ED, gives the faces formed by the passage of the rays B E, and C E, through the points of equal division B and C. Let us suppose the fortification to proceed inwards: in such case the lines A B, BC, CD, will be termed exterior sides, and all the principal will be formed within them; whereas, had it been intended to cover more ground, and to keep the whole of the area contained within the lines A B, BC, CD, and D C clear, the principal would have been projected outwards, and the lines A B, B C, CD, would then have been termed the interior side. The former mode is in use when the exterior of the defences is first marked out, and has its separate mode of formation; and the latter is adopted where the interior of the works is established by any pre-existing circumstances, such as fortifying an old town, &c.; and proceeds on a suitable plan of projection. The two modes correspond perfectly, giving the same angles and proportions; the former on a diminished, the latter on an extended scale. The interior lines FG, GH, HI, form parallel faces with those on the exterior lines A B, BC, CD. If it were required to fortify outwards, they would be the bases of their several defences respectively, and the measurements would be taken from them, in lieu of from the exterior line. We shall proceed according to the latter mode, it being the most common and the most familiar. To fortify inwards from an exterior line.— Let the exterior line BC, be 180 toises, (each toise being one fathom, or six feet,) bisect it in d, and draw the perpendicular d 8 equal to one sixth of the exterior line BC, namely, 30 toises. Now from B draw the line B v, passing through the point n; and from C draw the line Cu, intersecting B v in n. Set off 50 toises from the points B and C, on their respective lines, which |