ENGINEER CORPS. 80 This act amalgamated the cadet midship- ers under the title of naval that time all cadets have taken the same course for at least three of the four years at the Academy, and then have been divided, according to standing ur personal prefer- ences, between the line ai ' orps in proportion to vacancies in each. This method held until the amalgamation of the line and Engi- neer Corps under the act of March 3, 1899, by which the Engineer Corps lost its identity separa ation. The older officers of the orps are required to perform engineer- ing duties only, while the younger ones have to it examination in navigation, seamanship, gunnery, etc., and are required to perform any and all the duties of their respective grade-. By the same act of March 3. 1899, was estab- lished of warrant machinists who do most of the watch duties now, as there are too mmissioned officers to perform this im- portant work. ENGINEERING, Military. Military engi- neering in its broader sense is the application of engineering to military purposes. The term was J originally to distinguish it from civil engineering. In recent years there has been such t advance in certain branches of civil engineering (see Engikeeb and Engineering) as to entitle them to the rank of separate profes- as, for example, sun ■■■ ing, anitary engi- neering, mechanical engineering, and electrical engineering. The mechanical military engineer- ing connected with the development of guns and carriages has been gradually developed into the ait and sciei Inance (q.v.). Military sig- naling is now carried on in several armies either by signal corps or by detachments of engineer corps having practically no other duties to per- form. I See SIGN 1 M, M> Tl LEGBAPHING, MILI- TARY.) On the other hand, many of the problems presented to the military engineer are of such nature t hat oil ed bj direel applical ions of sanitarj i ihanical engineering, surveying, general civil engineering, electrical engineering, and architecture, with only slight modifications caused by the military conditions imposed on them. Such, for example, are topo- graphical surveys preliminary to the designing and construction of permanent fortifications, bar- racks, and i i 1 ii' Fo] i he sen ice of in tin f peace, and water-supply and drainage of military posts. In its more restricted sense, therefore, military engineering is now taken to include, on the one hand, those applica- nt' the various branches of engineering to military purposes where the military conditions remount, and. on I he other, to 1 hose opera led v, ii li t he movements of an army in all thai pertains to attack and defense, and to the de tion, and construction of perms neid works of land oasl defense inure iily known as fortifications. The subject being divided into, ■mill, perina- i pn en! ar ill ili al chiefl ii leal ores of in Id i will be made i he other iro- ei r. The Mibjei I is treated the tin. Mn. ii n'cy iii i i : i ubjeci ENGINEERING. comprises primarily those applications of engi- neering in the held where the prime element to be considered is the amount of time available, the nature of the labor, and the material at hand. From the nature of the movements of large bodies of troops, it is usually impracticable to carry much material in addition to what is required for the maintenance of the army on the simplest practicable basis. Field engineering, therefore, to be successful must rely largely on the resource- fulness of its representatives. The military engi- neer who can be relied on to secure a result suf- ficiently good to answer the purpose in the time allowed will be far more successful in the field than one of greater attainments whose disposition prevents him from taking short cuts and from being satisfied with any work short of perfec- tion. Under the head of Military Field Engineer- ing the following divisions of the subject may be made: Field measurements, clearing of land, encampments, military surveys and maps, com- munications, field fortification, siege works, and military mining. Of the topics included in this division of the subject, field measurement, clearing of ground, military surveys, topographical reconnoissanee and maps, being more or less closely related, will be described in the present article, while separate articles to which the reader is referred will treat the subjects of Encampments ; Roads and Rail- p.oads, Military; Bridges and Docks, Mili- tary: Demolition; Mines and Mining, Mili- tary - ; Siege Works ; and Fortification. Field Measurements. The rapid approxi- mate measurement of distances is frequently necessary in field operations. For short dis- tances resort is had to the use of the rule and tape. For longer distances, where both extreme points are accessible, measurement is ordinarily made by pacing, running over .the line with a wheel, or by estimation with the eye. With practice many officers become extremely expert in the determination of distances by the eye. Where the distance to some inaccessible point, as, for example, a tree on the opposite bank of a river, is required more accurately than would probably be given by simple estimation, a method frequently used is the' following: To find the distal from B to O, being on the B side of the river, lay off a line at right angles to OB, and stake some point on Ibis line as C. At an intermediate point in the line BC. as D, lay off a line al right angles to BC. Mark the poinl E when' the lino of sight from C to crosses DE. Then, by similar triangles, having measured DE, DC, and Clt. we will have BO : BC : : DE : DC. There- fore, no — BC X DE S -5- DC. By a similar but slightly more com- plicated process, the heigh! of a distant in- acce il'h' |" ml can be _ deleriniiii d. 01 her sim- B pie and prad Leal meth ods for measuring sim- ilar distances are de Bribed in the field-engineer- ing manuals. One of the simplesl ways of laying ^- Fio.2.
