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better plans without them; and, moreover, I hold them all to be inferior to the simple method of measuring an angle on the ground with a view to laying it down on paper.

"On the simple principle, derived from the properties of the triangle, by which a survey of great accuracy can be made with the land-chain, I assert that we may make excellent plans of military positions, and even construct district maps, without the aid of any kind of instruments, whether for angular or linear measurement. It is true that such maps, if of a considerable extent of country, could have little pretentions to geometrical accuracy, but they would nevertheless be fully adequate to every military purpose: while they would, at the same time, have the great advantage of being rapidly executed—a material consideration during active warfare. •

"The necessary measurements for reconnoissance, plans, and maps, may be made in four ways, according to the degree of accuracy required; these are,

"1st. By pacing, using the marching step of thirty inches.

"2ndly. By counting the paces of a horse, whose length of step has been accurately measured.

"3rdly. By timing a horse when walking.

"4thly. By obtaining the distances which separate towns, from the inhabitants of the country.

"In a flat country, the towns and villages are usually connected by roads running tolerably direct; and if the distances between any three, forming a triangle, are obtained by one of the above methods, the relative situations of those places can be laid down on paper, and the positions of other places may afterwards be determined from any two of them as a base. In a mountainous district, however, it would not do to measure distances by keeping to the roads, as these generally take the most convenient, rather than the shortest, way of reaching any particular spot; so that two places may lie six miles apart, reckoning by the road between them, while geographically they may not be half that distance asunder.

"To illustrate this method of sketching, let us suppose a tree, A, a windmill, B, and a house, C, forming a triangle, whose sides we can measure by pacing. Having laid down our triangle, we proceed to make our sketch, thus:—Beginning at A, we find that at 500 paces towards B we cross a road leading to a bridge, of which we sketch the direction. Continuing along the line A B, we notice when we reach a point, d, where a line to the bridge would form a right angle with A B, ascertaining the point d by fronting the bridge and performing "right face." This fixes the bridge. Proceeding on towards B, we come to the rivulet, which is sketched as far as the bridge, and also in the opposite direction. We now mount the hill to B, and by measuring at right angles to /, we obtain the road from the bridge upwards. After sketching the ground about B, we descend in the direction of C, and as we proceed, sketching in the rivulet, bridge, and road, and then work in like manner towards A."

In these instructions, reference is made to an article on Tracing figures on tht ground, which is given in another portion of the work; and here the student will find some admirable hints on a point of. practical utility. Such lessons show us the importance of minute details, as the data and first steps of science, on which everything depends, and a mastery of the elements leads imperceptibly to the principles, and unfolds the whole theory of surveying. Moreover, by attention to little points the eye is trained to observation, as well as to accuracy, and learns to grasp every object. The operation of drawing a line upon the ground through two given points, by means of a staff placed at each extremity, and a third planted in the space between them, so that the eye, looking from the edge of one staff, finds the edges of the other two in accord, appears simple enough, but it hoth requires and imparts great precision of sight. Again, there seems to be no difficulty in walking in a straight line from a proposed point to a given object, but, in reality, it calls for some vigilance, and communicates a corresponding alertness of observation. The result is accomplished by fixing upon some point, as a bush or a stone, which may happen to be in a line with the object in question, and walking forward with the two objects strictly in line with the eye, selecting a fresh mark when within twenty or thirty paces of the final point. To trace a line in the direction of two distant points, with the same degree of accuracy, may easily be done by two persons, standing fifty or sixty paces apart, and each placing the other, by motions of the hand, in a line with the particular objects; or, with the assistance of staves, one person may effect the operation unaided, but not with the same dispatch. Colonel Jackson remarks, "I have found such little expedients very useful in practice, or I should not have ventured to mention them here, as some might consider them puerile;" but, in fact, it is the gallant author's attention to things that others might pass over, that renders his instructions so valuable, and gives his book that eminently practical character which has rendered it so widely popular.

Every officer should be competent to execute a rough plan of a military position; and a mere cursory perusal of Colonel Jackson's book will qualify him for the task, and, indeed, for more elaborate achievements. But let us confine ourselves to the simplest method of sketching a military position with the aid of a compass. How should we set about it? Our gallant instructor describes at once, in the clearest manner, what is to be done. First, the paper must be ruled with parallel lines at unequal distances. The ground, having been carefully scanned by the eye, and explored in every part, is, of course, strongly imprinted on the mind; every salient point has been observed, and we know exactly all the objects it embraces, especially noting remarkable trees, buildings, or such conspicuous marks as a windmill, or a church steeple. The base is measured on the longest and most level space, which may be either on the summit of the ground, or along the base, as convenience dictates. Bearings are taken with the compass, lines drawn, the ivory protractor brought into play, prominent objects singled out and fixed, care taken to avoid obtuse and acute intersections, the declivities and the contours of the hill sketched in, and the road laid down at particular points. The sketch may be extended over a wider tract, by taking bearings of distant objects, and determining their situations, but we must add that it is important to lay down a meridian line, and that each sketch should be furnished with a scale. Colonel Jackson, going fully into the subject, is very explicit as to the mode of proceeding, placing everything in a light so clear that it may be comprehended by the humblest capacity, while, on the other hand, it must be faithfully followed by the most expert. His observations are illustrated by plates and diagrams, which may serve as examples; for, in point of fact, they are not required to elucidate the text, however they may embellish it. But having seen how a military position is to be sketched, let us turn to the subject of reconnoissanue, which comes in at the end of the book, like a good moral, and is treated in the gallant author's happiest vein:—

"When the operations of a campaign are carried on in a country with whose nature, features, and resources a commander is unacquainted, his situation may be compared with that of a man groping his way in darkness: but if, on the contrary, he possess an accurate knowledge of the surface over which he has to operate, he may act with a boldness and decision that will often ensure success. If the theatre of war be in a semi-barbarous country, the accounts of observing travellers and intelligent natives will often prove of essential service; but if it lie in any country of Europe, the maps and statistical reports, published by authority, will always afford much useful information: in either case, a more particular knowledge—as, for instance, such as relates to the nature of the mountains, rivers, roads, woods, towns, villages, military position, &c.—can only be acquired from personal examination by active and intelligent officers. The process by which this examination is conducted, and the requisite information collected, is termed Military Eeconnoissance. This important duty belongs especially to the department of the Quartermaster-General, and the officers employed in it ought to be selected in consequence of their proficiency in military surveying and drawing, as linguists, and for general intelligence and activity.

"As there is no kind of service more likely to bring an officer into favourable notice than an able performance of the duty of reconnoissance, it is strenuously urged on young aspirants for staff employment diligently to apply their intervals of leisure, so as to acquire due proficiency in foreign languages, military surveying, and the practice of reconnoitring and framing reports on roads, rivers, and districts of country; and they may thus profitably exercise their attention during tours of pleasure.

"The greatest captains of modern days, Frederick, Napoleon, and Wellington, attached the utmost importance to this service, and Napoleon especially, as we gather from the pages of Odeleben's Relation rireotutanciet de la Campagne de 1813 en Saxe; wherein he gives in detail the organization of the Bureau Topographique, under Colonel Bacler d'Albe. Under Wellington the officers of the Royal Staff Corps constituted his Bureau Topographique, and were constantly employed under the orders of the Quartermaster-General. There are now at the Horse Guards detailed plans, on a large scale, of the whole of the French territory occupied by the British army during the space of three years after the Waterloo campaign; evidencing the great Duke's attention to this im

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portant service, even at a period when he had no reason to think a renewal of hostilities probable.

"It is not required of a staff-officer to sketch the whole of the country that he is to reconnoitre; there is not time for this in war; but it is essential that he be perfectly competent to sketch well, to enable him to give the details of the positions, and the principal points of his reconnoissance.

"To abridge this operation, before proceeding to the ground, he can, from a correct map of the country, fix the situations of cities, towns, and villages, on a scale susceptible of details, and afterwards sketch in the ground, while passing over it.

"The coup (Tail, or the talent of estimating distances, is of the first importance in reconnoitring; it may be acquired by constantly practising the eye to judge distances, and correcting its errors by afterwards measuring them. The position of the individual, with regard to the sun, makes a considerable difference, and it is necessary to accustom oneself to this difference, to avoid being led into errors by it: when facing the sun objects appear much nearer than when the back is to it. In taking a rapid reconnoissance of mountainous country there are other deceptions to which an unpractised officer is liable: he is apt greatly to over-estimate the degree of declivity of any extensive bluff slope, even when seen in profile, and much more when seen in elevation. Again, in looking down a valley he is pretty sure to underestimate the rapidity of descent in its longitudinal slope. Also, when standing on a mountain ridge, we are apt to think a knoll at the end of a spur is higher than our own position, though in reality the knoll is much lower. This deception is often very strong.

"A knowledge of fortification, if not absolutely indispensable to officers of the staff, is at least highly useful, as enabling them to report with accuracy upon any fortified places or works which may be in the district they have to reconnoitre; as also upon the facilities that open towns, villages, churches, houses, and buildings of every kind, may present for being fortified or retrenched; to mark likewise the proper sites for throwing up field-works, establishing batteries, &c, and those which from being commanded or enfiladed from points actually held by the enemy, or which they cannot be kept from occupying, would be improper for such purposes; and to calculate the time, labour, and materials required for the necessary works.

"It is indispensable that officers employed on a military reconnoissance should be good linguists generally, and that they should speak the language of the country in which they are to act fluently and correctly, and write it with accuracy. Without this the information they acquire must be extremely limited, and their reports must be, at best, meagre and unsatisfactory, if not positively incorrect. If entirely ignorant of the language, they must have recourse to interpreters to obtain intelligence from the inhabitants. Questions and answers coming thus at secondhand can never be so full and satisfactory as direct ones; besides which, the interpreters may be either faithless or incompetent; or, without being either, they may not, at the moment, catch the spirit of the interrogation or reply, although they may give a literal translation of the words employed. We are all aware how much in conversation depends on emphasis and intonation, and how various and widely different are the significations of which a single sentence is susceptible, by placing the emphasis on one word or member instead of another. If but slightly acquainted with the language, they must be constantly liable to have their questions misunderstood, and themselves, in turn, to misunderstand the answers given; whence it follows that their reports can never be depended on with certainty; they may be correct, but they may be the reverse, and if so, and acted upon as correct, how fatally irreparable may be the results of their errors.

"It is often highly useful to an officer to speak, or at least to understand, the patois of the peasantry and lower classes in a country, to enable him to communicate freely with them; as from such persons highly important information respecting fords, bye-ways, passes, &c, is often obtained.

"Too much attention cannot be given to the correct spelling and pronunciation of names of places, rivers, &c.; an omission or mistake of a single letter, nay even of an accent, may produce most serious consequences, by the confounding of one road, town, village, &c, with another, which may perhaps lie in a direction altogether different from that intended. It often happens that a person asks a peasant the situation of certain villages as the names are given on the map, and finds that he is altogether ignorant of such places, because his pronunciation of the names is totally different."

Here we must leave this instructive—we had almost said this amusing book; for the topics of which it treats possess so much interest, and they are handled in so attractive a manner, that instruction takes a form as agreeable as it is useful. Such is the aspect which science should ever assume; for, in reality, nothing is so engaging—nothing so fascinates the understanding and the faculties; but it is generally presented in such a hard, dry, indigestible shape, that its true nature is not understood. Colonel Jackson teaches, as he writes, with equal ability and power. His treatise has become a class-book at two of our colleges, and every officer who desires to advance himself in his profession should make it his study. 8. W. F.

Coast Defences In Scotland.—The War Office is busied at present putting the coast defences of Scotland into repair and adding to their strength. At Aberdeen three new batteries manned by 16 guns are to be erected, by which the harbour and town will be defended from any attack on the seaboard. Lord Palmerston has sent a number of Russian guns as war trophies t» Aberdeen, Elgin, and other towns in the north.

Bottle Tracts.—Bottles cast into the sea often render better service to science than the thoughts or theories of man. The chart drawn up by the late Admiral Beechey, representing the tracks of more than a hundred bottles, s"'Ows that all the equatorial waters of the Atlantic tend westward towards the Mexican Gulf, to issue thence in the Gulf-stream. Those thrown overhoardin mid-ocean, or any part of the African coast, have been found, after a certain lnpse of time, either in the West Indies, or on the British shores, or floating in the course of the Gulf-stream between. There is even reason to believe that some of these bottles have been discovered on their second circuit; arrested probably on the coasts of Sp;iiu by the drift southwards, carried along the African const into the equatorial seas, and thence again across the Atlantic to the Gulf of Mexico.

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