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
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 (see Architecture: Construction), automotive
engineering, ceramic engineering, transportation engineering, and textile
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 aerodynamics, structural design, propulsion engines,
navigation, communication, and other related areas. See Airplane; Aviation.
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. See Space Exploration.
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
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: (1) the conservation of matter; (2) the conservation
of energy; (3) the principles of chemical equilibrium; (4) 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 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. Among the most important
subjects in the field in the late 1980s are electric power and machinery,
electronic circuits, control systems, computer design, superconductors,
solid-state electronics, medical imaging systems, robotics, lasers, radar,
consumer electronics, and fiber optics.
Despite its diversity, electrical engineering can be divided into four
main branches: electric power and machinery, electronics, communications
and control, and computers.
Electric Power and Machinery
The field of electric power is concerned with the design and operation
of systems for generating, transmitting, and distributing electric power.
Engineers in this field have brought about several important developments
since the late 1970s. One of these is the ability to transmit power at
extremely high voltages in both the direct current (DC) and alternating
current (AC) modes, reducing power losses proportionately. Another is the
real-time control of power generation, transmission, and distribution,
using computers to analyze the data fed back from the power system to a
central station and thereby optimizing the efficiency of the system while
it is in operation.
A significant advance in the engineering of electric machinery has
been the introduction of electronic controls that enable AC motors to run
at variable speeds by adjusting the frequency of the current fed into them.
DC motors have also been made to run more efficiently this way. See also
Electric Motors and Generators; Electric Power Systems.
Electronic engineering deals with the research, design, integration,
and application of circuits and devices used in the transmission and processing
of information. Information is now generated, transmitted, received, and
stored electronically on a scale unprecedented in history, and there is
every indication that the explosive rate of growth in this field will continue
Electronic engineers design circuits to perform specific tasks, such
as amplifying electronic signals, adding binary numbers, and demodulating
radio signals to recover the information they carry. Circuits are also
used to generate waveforms useful for synchronization and timing, as in
television, and for correcting errors in digital information, as in telecommunications.
See also Electronics.
Prior to the 1960s, circuits consisted of separate electronic devices-resistors,
capacitors, inductors, and vacuum tubes-assembled on a chassis and connected
by wires to form a bulky package. Since then, there has been a revolutionary
trend toward integrating electronic devices on a single tiny chip of silicon
or some other semiconductive material. The complex task of manufacturing
these chips uses the most advanced technology, including computers, electron-beam
lithography, micro-manipulators, ion-beam implantation, and ultraclean
environments. Much of the research in electronics is directed toward creating
even smaller chips, faster switching of components, and three-dimensional
Communications and Control
Engineers in this field are concerned with all aspects of electrical
communications, from fundamental questions such as "What is information?"
to the highly practical, such as design of telephone systems. In designing
communication systems, engineers rely heavily on various branches of advanced
mathematics, such as Fourier analysis, linear systems theory, linear algebra,
complex variables, differential equations, and probability theory. See
also Mathematics; Matrix Theory and Linear Algebra; Probability.
Engineers work on control systems ranging from the everyday, passenger-actuated,
as those that run an elevator, to the exotic, as systems for keeping spacecraft
on course. Control systems are used extensively in aircraft and ships,
in military fire-control systems, in power transmission and distribution,
in automated manufacturing, and in robotics.
Engineers have been working to bring about two revolutionary changes
in the field of communications and control: Digital systems are replacing
analog ones at the same time that fiber optics are superseding copper cables.
Digital systems offer far greater immunity to electrical noise. Fiber optics
are likewise immune to interference; they also have tremendous carrying
capacity, and are extremely light and inexpensive to manufacture.
Virtually unknown just a few decades ago, computer engineering is now
among the most rapidly growing fields. The electronics of computers involve
engineers in design and manufacture of memory systems, of central processing
units, and of peripheral devices (see Computer). Foremost among the avenues
now being pursued are the design of Very Large Scale Integration (VLSI)
and new computer architectures. The field of computer science is closely
related to computer engineering; however, the task of making computers
more "intelligent" (artificial intelligence,), through creation of sophisticated
programs or development of higher level machine languages or other means,
is generally regarded as being in the realm of computer science.
One current trend in computer engineering is microminiaturization.
Using VLSI, engineers continue to work to squeeze greater and greater numbers
of circuit elements onto smaller and smaller chips. Another trend is toward
increasing the speed of computer operations through use of parallel processors,
superconducting materials, and the like.
Geological and Mining Engineering
This branch of engineering includes activities related to the discovery
and exploration of mineral deposits and the financing, construction, development,
operation, recovery, processing, purification, and marketing of crude minerals
and mineral products. The mining engineer is trained in historical geology,
mineralogy, paleontology, and geophysics, and employs such tools as the
seismograph and the magnetometer for the location of ore or petroleum deposits
beneath the surface of the earth (see Petroleum; Seismology). The surveying
and drawing of geological maps and sections is an important part of the
work of the engineering geologist, who is also responsible for determining
whether the geological structure of a given location is suitable for the
building of such large structures as dams.
Industrial or Management Engineering
This field pertains to the efficient use of machinery, labor, and raw
materials in industrial production. It is particularly important from the
viewpoint of costs and economics of production, safety of human operators,
and the most advantageous deployment of automatic machinery.
Engineers in this field design, test, build, and operate machinery
of all types; they also work on a variety of manufactured goods and certain
kinds of structures. The field is divided into (1) machinery, mechanisms,
materials, hydraulics, and pneumatics; and (2) heat as applied to engines,
work and energy, heating, ventilating, and air conditioning. The mechanical
engineer, therefore, must be trained in mechanics, hydraulics, and thermodynamics
and must be fully grounded in such subjects as metallurgy and machine design.
Some mechanical engineers specialize in particular types of machines such
as pumps or steam turbines. A mechanical engineer designs not only the
machines that make products but the products themselves, and must design
for both economy and efficiency. A typical example of the complexity of
modern mechanical engineering is the design of an automobile, which entails
not only the design of the engine that drives the car but also all its
attendant accessories such as the steering and braking systems, the lighting
system, the gearing by which the engine's power is delivered to the wheels,
the controls, and the body, including such details as the door latches
and the type of seat upholstery.
This branch is concerned with the application of the engineering sciences
to military purposes. It is generally divided into permanent land defense
(see Fortification and Siege Warfare) and field engineering. In war, army
engineer battalions have been used to construct ports, harbors, depots,
and airfields. In the U.S., military engineers also construct some public
works, national monuments, and dams (see Army Corps of Engineers).
Military engineering has become an increasingly specialized science,
resulting in separate engineering subdisciplines such as ordnance, which
applies mechanical engineering to the development of guns and chemical
engineering to the development of propellants, and the Signal Corps, which
applies electrical engineering to all problems of telegraph, telephone,
radio, and other communication.
Naval or Marine Engineering
Engineers who have the overall responsibility for designing and supervising
construction of ships are called naval architects. The ships they design
range in size from ocean-going supertankers as much as 1300 feet long to
small tugboats that operate in rivers and bays. Regardless of size, ships
must be designed and built so that they are safe, stable, strong, and fast
enough to perform the type of work intended for them. To accomplish this,
a naval architect must be familiar with the variety of techniques of modern
shipbuilding, and must have a thorough grounding in applied sciences, such
as fluid mechanics, that bear directly on how ships move through water.
Marine engineering is a specialized branch of mechanical engineering
devoted to the design and operation of systems, both mechanical and electrical,
needed to propel a ship. In helping the naval architect design ships, the
marine engineer must choose a propulsion unit, such as a diesel engine
or geared steam turbine, that provides enough power to move the ship at
the speed required. In doing so, the engineer must take into consideration
how much the engine and fuel bunkers will weigh and how much space they
will occupy, as well as the projected costs of fuel and maintenance. See
also Ships and Shipbuilding.
This branch of engineering is concerned with the design and construction
of nuclear reactors and devices, and the manner in which nuclear fission
may find practical applications, such as the production of commercial power
from the energy generated by nuclear reactions and the use of nuclear reactors
for propulsion and of nuclear radiation to induce chemical and biological
changes. In addition to designing nuclear reactors to yield specified amounts
of power, nuclear engineers develop the special materials necessary to
withstand the high temperatures and concentrated bombardment of nuclear
particles that accompany nuclear fission and fusion. Nuclear engineers
also develop methods to shield people from the harmful radiation produced
by nuclear reactions and to ensure safe storage and disposal of fissionable
materials. See Nuclear Energy.
This field of engineering has as its object the prevention of accidents.
In recent years safety engineering has become a specialty adopted by individuals
trained in other branches of engineering. Safety engineers develop methods
and procedures to safeguard workers in hazardous occupations. They also
assist in designing machinery, factories, ships, and roads, suggesting
alterations and improvements to reduce the likelihood of accident. In the
design of machinery, for example, the safety engineer seeks to cover all
moving parts or keep them from accidental contact with the operator, to
put cutoff switches within reach of the operator, and to eliminate dangerous
projecting parts. In designing roads the safety engineer seeks to avoid
such hazards as sharp turns and blind intersections, known to result in
traffic accidents. Many large industrial and construction firms, and insurance
companies engaged in the field of workers compensation, today maintain
safety engineering departments. See Industrial Safety; National Safety
This is a branch of civil engineering, but because of its great importance
for a healthy environment, especially in dense urban-population areas,
it has acquired the importance of a specialized field. It chiefly deals
with problems involving water supply, treatment, and distribution; disposal
of community wastes and reclamation of useful components of such wastes;
control of pollution of surface waterways, groundwaters, and soils; milk
and food sanitation; housing and institutional sanitation; rural and recreational-site
sanitation; insect and vermin control; control of atmospheric pollution;
industrial hygiene, including control of light, noise, vibration, and toxic
materials in work areas; and other fields concerned with the control of
environmental factors affecting health. The methods used for supplying
communities with pure water and for the disposal of sewage and other wastes
are described separately. See Plumbing; Sewage Disposal; Solid Waste Disposal;
Water Pollution; Water Supply and Waterworks.
Modern Engineering Trends
Scientific methods of engineering are applied in several fields not
connected directly to manufacture and construction. Modern engineering
is characterized by the broad application of what is known as systems engineering
principles. The systems approach is a methodology of decision-making in
design, operation, or construction that adopts (1) the formal process included
in what is known as the scientific method; (2) an interdisciplinary, or
team, approach, using specialists from not only the various engineering
disciplines, but from legal, social, aesthetic, and behavioral fields as
well; (3) a formal sequence of procedure employing the principles of operations
In effect, therefore, transportation engineering in its broadest sense
includes not only design of the transportation system and building of its
lines and rolling stock, but also determination of the traffic requirements
of the route followed. It is also concerned with setting up efficient and
safe schedules, and the interaction of the system with the community and
the environment. Engineers in industry work not only with machines but
also with people, to determine, for example, how machines can be operated
most efficiently by the workers. A small change in the location of the
controls of a machine or of its position with relation to other machines
or equipment, or a change in the muscular movements of the operator, often
results in greatly increased production. This type of engineering work
is called time-study engineering.
A related field of engineering, human-factors engineering, also known
as ergonomics, received wide attention in the late 1970s and the '80s when
the safety of nuclear reactors was questioned following serious accidents
that were caused by operator errors, design failures, and malfunctioning
equipment. Human-factors engineering seeks to establish criteria for the
efficient, human-centered design of, among other things, the large, complicated
control panels that monitor and govern nuclear reactor operations.
Among various recent trends in the engineering profession, licensing
and computerization are the most widespread. Today, many engineers, like
doctors and lawyers, are licensed by the state. Approvals by professionally
licensed engineers are required for construction of public and commercial
structures, especially installations where public and worker safety is
a consideration. The trend in modern engineering offices is overwhelmingly
toward computerization. Computers are increasingly used for solving complex
problems as well as for handling, storing, and generating the enormous
volume of data modern engineers must work with.
The National Academy of Engineering, founded in 1964 as a private organization,
sponsors engineering programs aimed at meeting national needs, encourages
new research, and is concerned with the relationship of engineering to
"Engineering," Microsoft(R) Encarta(R) 97 Encyclopedia. (c) 1993-1996
Microsoft Corporation. All rights reserved.