Engineering
    
    Engineering, term applied to the profession in which a knowledge of the mathematical and natural sciences, gained by study, experience, and practice, is applied to the efficient use of the materials and forces of nature. The term engineer properly denotes a person who has received professional training in pure and applied science, but is often loosely used to describe the operator of an engine, as in the terms locomotive engineer, marine engineer, or stationary engineer. In modern terminology these latter occupations are known as crafts or trades. Between the professional engineer and the craftsperson or tradesperson, however, are those individuals known as subprofessionals or paraprofessionals, who apply scientific and engineering skills to technical problems; typical of these are engineering aides, technicians, inspectors, draftsmen, and the like.
    Before the middle of the 18th century, large-scale construction work was usually placed in the hands of military engineers. Military engineering involved such work as the preparation of topographical maps, the location, design, and construction of roads and bridges; and the building of forts and docks; see Military Engineering below. In the 18th century, however, the term civil engineering came into use to describe engineering work that was performed by civilians for nonmilitary purposes. With the increasing use of machinery in the 19th century, mechanical engineering was recognized as a separate branch of engineering, and later mining engineering was similarly recognized.
    The technical advances of the 19th century greatly broadened the field of engineering and introduced a large number of engineering specialties, and the rapidly changing demands of the socioeconomic environment in the 20th century have widened the scope even further.
    Fields of Engineering
    The main branches of engineering are discussed below in alphabetical order. The engineer who works in any of these fields usually requires a basic knowledge of the other engineering fields, because most engineering problems are complex and interrelated. Thus a chemical engineer designing a plant for the electrolytic refining of metal ores must deal with the design of structures, machinery, and electrical devices, as well as with purely chemical problems.
    Besides the principal branches discussed below, engineering includes many more specialties than can be described here, such as acoustical engineering , architectural engineering automotive engineering, ceramic engineering, transportation engineering, and textile engineering.
    Aeronautical and Aerospace Engineering
    Aeronautics deals with the whole field of design, manufacture, maintenance, testing, and use of aircraft for both civilian and military purposes. It involves the knowledge of , structural design, propulsion engines, navigation, communication, and other related areas.
    Aerospace engineering is closely allied to aeronautics, but is concerned with the flight of vehicles in space, beyond the earth's atmosphere, and includes the study and development of rocket engines, artificial satellites, and spacecraft for the exploration of outer space.
    Chemical Engineering
    
    This branch of engineering is concerned with the design, construction, and management of factories in which the essential processes consist of chemical reactions. Because of the diversity of the materials dealt with, the practice, for more than 50 years, has been to analyze chemical engineering problems in terms of fundamental unit operations or unit processes such as the grinding or pulverizing of solids. It is the task of the chemical engineer to select and specify the design that will best meet the particular requirements of production and the most appropriate equipment for the new applications.
    With the advance of technology, the number of unit operations increases, but of continuing importance are distillation, crystallization, dissolution, filtration, and extraction. In each unit operation, engineers are concerned with four fundamentals: the conservation of matter; the conservation of energy; the principles of chemical equilibrium; the principles of chemical reactivity. In addition, chemical engineers must organize the unit operations in their correct sequence, and they must consider the economic cost of the overall process. Because a continuous, or assembly-line, operation is more economical than a batch process, and is frequently amenable to automatic control, chemical engineers were among the first to incorporate automatic controls into their designs.
    Civil Engineering
    
    Civil engineering is perhaps the broadest of the engineering fields, for it deals with the creation, improvement, and protection of the communal environment, providing facilities for living, industry and transportation, including large buildings, roads, bridges, canals, railroad lines, airports, water-supply systems, dams, irrigation, harbors, docks, aqueducts, tunnels, and other engineered constructions. The civil engineer must have a thorough knowledge of all types of surveying, of the properties and mechanics of construction materials, the mechanics of structures and soils, and of hydraulics and fluid mechanics. Among the important subdivisions of the field are construction engineering, irrigation engineering, transportation engineering, soils and foundation engineering, geodetic engineering, hydraulic engineering, and coastal and ocean engineering.
    Electrical and Electronics Engineering
    
    The largest and most diverse field of engineering, it is concerned with the development and design, application, and manufacture of systems and devices that use electric power and signals. ............