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telegraph ► televangelism I 1883
telegraph Electromagnetic communication device. In 1832 Samuel F.B. Morse made sketches of ideas for a system of electric telegraphy, and in 1835 he developed a code to represent letters and numbers (Morse code). In 1837 he was granted a patent on an electromagnetic telegraph that transmitted signals along a wire. That same year British inventors pat¬ ented a telegraph system that activated five needle pointers that could be made to point to specific letters and numbers on their mounting plate. Public use of Morse’s telegraph system began in 1844 and lasted more than 100 years. By the late 20th century the telegraph had been replaced in most applications in developed countries by digital data transmission systems based on computer technology. See also Western Union Corp.
Teleki Vte-le-kiV, Pal, Count (b. Nov. 1, 1879, Budapest, Hung., Austria-Hungary—d. April 3, 1941, Budapest) Hungarian politician. An eminent geographer, he was a member of the Hungarian Parliament from 1905 and a delegate to the Paris Peace Conference (1919) after World War I. In 1921, however, he withdrew from party politics. He then taught at Budapest University before returning to office as minister of education (1938-39) and premier (1939—41). Hoping to use Germany’s power to win back territories lost through the Treaty of Trianon (1920), he initially cooperated with Adolf Hitler. In 1941, caught between German demands for support after it invaded Yugoslavia (with whom Hungary had signed a friendship treaty in 1940) and British threats against helping Germany, he committed suicide.
Telemann \'ta-b-,man\, Georg Philipp (b. March 14, 1681, Magde¬ burg, Brandenburg—d. June 25, 1767, Hamburg) German composer. By age 10 he had learned several instruments, and he composed an opera at age 12, but his family discouraged his pursuit of a musical profession. While studying law at Leipzig University, he organized student music groups and became music director of the Leipzig Opera (1702), organist at the New Church (1704), and kapellmeister to a count (1705). Moving to Eisenach (c. 1708), where he met Johann Sebastian Bach, he composed French-style instrumental music and German-style sacred music. He moved to Gotha (1717) and then Hamburg (1721), where he served as musical director of the Opera (1722-38), for which he wrote several dozen Italian-influenced works. He wrote some 600 cantatas and a total of some 2,000 pieces, many of high quality.
telemetry \t3-Te-mo-tre\ Highly automated communications process by which data are collected from instruments located at remote or inaccessible points and transmitted to receiving equipment for measurement, monitor¬ ing, display, and recording. Transmission of the information may be over wires or, more commonly, by radio. The technique is used extensively for oil-pipeline monitoring and control systems and in oceanography and meteorology. Telemetry for rockets and satellites bloomed in the 1950s and has continued to grow in complexity and in breadth of application. Data can be transmitted from inside internal-combustion engines during tests, from steam turbines in operation, and from manned and unmanned spacecraft. Major scientific applications include biomedical research and remote observation of operations with highly radioactive material.
teleological argument See argument from design
teleological ethics Theory that derives duty from what is valuable as an end, in a manner diametrically opposed to deontological ethics. Teleo¬ logical ethics holds that the basic standard of duty is the contribution that an action makes to the realization of nonmoral values. Teleological theo¬ ries differ on the nature of the nonmoral goods that actions ought to pro¬ mote. Eudaemonism emphasizes the cultivation of virtue in the agent as the end of all action. Utilitarianism holds that the end consists in the aggregate balance of pleasure to pain for all concerned. Other teleological theories claim that the end of action is survival and growth, as in evolutionary ethics (Herbert Spencer); power over others (Niccolo Machiavelu and Friedrich Nietzsche); satisfaction and adjustment, as in pragmatism (Ralph Barton Perry and John Dewey); and freedom, as in existentialism (Jean-Paul Sartre).
teleology \,te-le-'a-b-je\ Causality in which the effect is explained by an end (Greek, telos ) to be realized. Teleology thus differs essentially from efficient causality, in which an effect is dependent on prior events. Aris¬ totle’s account of teleology declared that a full explanation of anything must consider its final cause—the purpose for which the thing exists or was produced. Following Aristotle, many philosophers have conceived of biological processes as involving the operation of a guiding end. Modem science has tended to appeal only to efficient causes in its investigations. See also mechanism.
telephone Instrument designed for simultaneous transmission and reception of the human voice. It works by converting the sound waves of the human voice to pulses of electrical current, transmitting the current, and then retranslating the current back to sound. The U.S. patent granted to Alexander Graham Bell in 1876 for developing a device to transmit speech sounds over electric wires is often called the most valuable ever issued. Within 20 years, the telephone acquired a form that has remained fundamentally unchanged for more than a century. The advent of the transistor (1947) led to lightweight, compact circuitry (see cell phone). Advances in electronics have allowed the introduction of a number of “smart” features such as automatic redialing, caller identification, call waiting, and call forwarding. Telephone systems are also a primary access route for the Internet.
telescope Device that collects light from and magnifies images of dis¬ tant objects, undoubtedly the most important investigative tool in astronomy. The first telescopes focused visible light by refraction through LENSes; later instruments used reflection from curved mirrors (see optics). Their invention is traditionally credited to Hans Lippershey (15707- lb 19?), who adapted A. van Leeuwenhoek’s use of lenses in microscopes. Among the earliest telescopes were Galilean telescopes, modeled after the simple instruments built by Galileo, who was the first to use telescopes to study celestial bodies. In 1611 Johannes Kepler proposed an improved version that became the basis for modem refracting instruments. The reflecting telescope came into its own after William Herschel (see Her- schel family) used one to discover the planet Uranus in 1781. Since the 1930s radio telescopes have been used to detect and form images from radio waves emitted by celestial objects. More recently, telescopes have been designed to observe objects and phenomena in other parts of the ELECTROMAGNETIC SPECTRUM (see GAMMA-RAY ASTRONOMY; INFRARED ASTRONOMY;
ultraviolet astronomy; X-ray astronomy). Spaceflight has allowed tele¬ scopes to be launched into Earth orbit to avoid the light-scattering and light-absorbing effects of the atmosphere (e.g., the Hubble Space Telescope). See also binoculars; observatory.
objective lens eyepiece lens
incoming light
Two types of telescopes. A refracting telescope forms an image by focusing light from a distant object using an objective lens. A reflecting telescope uses mirrors to focus the light. Both types use a lens in the eyepiece to magnify the image formed.
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Teletype Telegraphic instrument that was used for much of the 20th century to transmit and receive printed messages and data via telephone cables or radio relay systems. Teletypewriters (or teleprinters) became common for commercial use in the 1920s. In 1924 the Teletype Corp. introduced a series of teletypewriters so popular that the name Teletype became synonymous with teleprinters in the U.S. Coding schemes used for teleprinters included a variation of the Baudot code (1920s) and ASCII (1960s). (See Jean-Maurice-Emile Baudot.) With the advent of high-speed data transmission in the 1980s, teletype gave way to e-mail and fax.