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Magnetic telegraph
(gcide) | Magnetic \Mag*net"ic\, Magnetical \Mag*net"ic*al\, a. [L.
magneticus: cf. F. magn['e]tique.]
1. Pertaining to the magnet; possessing the properties of the
magnet, or corresponding properties; as, a magnetic bar of
iron; a magnetic needle.
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2. Of or pertaining to, or characterized by, the earth's
magnetism; as, the magnetic north; the magnetic meridian.
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3. Capable of becoming a magnet; susceptible to magnetism;
as, the magnetic metals.
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4. Endowed with extraordinary personal power to excite the
feelings and to win the affections; attractive; inducing
attachment.
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She that had all magnetic force alone. --Donne.
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5. Having, susceptible to, or induced by, animal magnetism,
so called; hypnotic; as, a magnetic sleep. See
Magnetism. [Archaic]
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Magnetic amplitude, attraction, dip, induction, etc.
See under Amplitude, Attraction, etc.
Magnetic battery, a combination of bar or horseshoe magnets
with the like poles adjacent, so as to act together with
great power.
Magnetic compensator, a contrivance connected with a ship's
compass for compensating or neutralizing the effect of the
iron of the ship upon the needle.
Magnetic curves, curves indicating lines of magnetic force,
as in the arrangement of iron filings between the poles of
a powerful magnet.
Magnetic elements.
(a) (Chem. Physics) Those elements, as iron, nickel,
cobalt, chromium, manganese, etc., which are capable
or becoming magnetic.
(b) (Physics) In respect to terrestrial magnetism, the
declination, inclination, and intensity.
(c) See under Element.
Magnetic fluid, the hypothetical fluid whose existence was
formerly assumed in the explanations of the phenomena of
magnetism; -- no longer considered a meaningful concept.
Magnetic iron, or Magnetic iron ore. (Min.) Same as
Magnetite.
Magnetic needle, a slender bar of steel, magnetized and
suspended at its center on a sharp-pointed pivot, or by a
delicate fiber, so that it may take freely the direction
of the magnetic meridian. It constitutes the essential
part of a compass, such as the mariner's and the
surveyor's.
Magnetic poles, the two points in the opposite polar
regions of the earth at which the direction of the dipping
needle is vertical.
Magnetic pyrites. See Pyrrhotite.
Magnetic storm (Terrestrial Physics), a disturbance of the
earth's magnetic force characterized by great and sudden
changes.
magnetic tape (Electronics), a ribbon of plastic material
to which is affixed a thin layer of powder of a material
which can be magnetized, such as ferrite. Such tapes are
used in various electronic devices to record fluctuating
voltages, which can be used to represent sounds, images,
or binary data. Devices such as audio casette recorders,
videocasette recorders, and computer data storage devices
use magnetic tape as an inexpensive medium to store data.
Different magnetically susceptible materials are used in
such tapes.
Magnetic telegraph, a telegraph acting by means of a
magnet. See Telegraph.
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Electro-magnetic telegraph
(gcide) | Telegraph \Tel"e*graph\, n. [Gr. ? far, far off (cf. Lith. toli)
+ -graph: cf. F. t['e]l['e]graphe. See Graphic.]
An apparatus, or a process, for communicating intelligence
rapidly between distant points, especially by means of
preconcerted visible or audible signals representing words or
ideas, or by means of words and signs, transmitted by
electrical action.
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Note: The instruments used are classed as indicator,
type-printing, symbol-printing, or chemical-printing
telegraphs, according as the intelligence is given by
the movements of a pointer or indicator, as in Cooke &
Wheatstone's (the form commonly used in England), or by
impressing, on a fillet of paper, letters from types,
as in House's and Hughe's, or dots and marks from a
sharp point moved by a magnet, as in Morse's, or
symbols produced by electro-chemical action, as in
Bain's. In the offices in the United States the
recording instrument is now little used, the receiving
operator reading by ear the combinations of long and
short intervals of sound produced by the armature of an
electro-magnet as it is put in motion by the opening
and breaking of the circuit, which motion, in
registering instruments, traces upon a ribbon of paper
the lines and dots used to represent the letters of the
alphabet. See Illustration in Appendix, and {Morse
code}.
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Note: In 1837, Samuel F. B. Morse, an American artist,
devised a working electric telegraph, based on a rough
knowledge of electrical circuits, electromagnetic
induction coils, and a scheme to encode alphabetic
letters. He and his collaborators and backers
campaigned for years before persuading the federal
government to fund a demonstration. Finally, on May 24,
1844, they sent the first official long-distance
telegraphic message in Morse code, "What hath God
wrought," through a copper wire strung between
Washington, D.C., to Baltimore, Maryland. The phrase
was taken from the Bible, Numbers 23:23. It had been
suggested to Morse by Annie Ellworth, the young
daughter of a friend. --Library of Congress, American
Memories series
(http://memory.loc.gov/ammem/today/may24.html).
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Acoustic telegraph. See under Acoustic.
Dial telegraph, a telegraph in which letters of the
alphabet and numbers or other symbols are placed upon the
border of a circular dial plate at each station, the
apparatus being so arranged that the needle or index of
the dial at the receiving station accurately copies the
movements of that at the sending station.
Electric telegraph, or Electro-magnetic telegraph, a
telegraph in which an operator at one station causes words
or signs to be made at another by means of a current of
electricity, generated by a battery and transmitted over
an intervening wire.
Facsimile telegraph. See under Facsimile.
Indicator telegraph. See under Indicator.
Pan-telegraph, an electric telegraph by means of which a
drawing or writing, as an autographic message, may be
exactly reproduced at a distant station.
Printing telegraph, an electric telegraph which
automatically prints the message as it is received at a
distant station, in letters, not signs.
Signal telegraph, a telegraph in which preconcerted
signals, made by a machine, or otherwise, at one station,
are seen or heard and interpreted at another; a semaphore.
Submarine telegraph cable, a telegraph cable laid under
water to connect stations separated by a body of water.
Telegraph cable, a telegraphic cable consisting of several
conducting wires, inclosed by an insulating and protecting
material, so as to bring the wires into compact compass
for use on poles, or to form a strong cable impervious to
water, to be laid under ground, as in a town or city, or
under water, as in the ocean.
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