Definitions
from The Century Dictionary.
- noun In electricity, a tube filled with a conducting substance in powdered or granular form, as metal filings, which, when struck by an electric wave, as that sent out from a wireless telegraph station, decreases in electrical resistance, probably by the particles making a better contact with each other, and so is used to discover very minute electric waves, as in wireless telegraphy. After the passing of the electric wave the resistance of the coherer usually remains low, but it rises again when the tube is tapped.
from the GNU version of the Collaborative International Dictionary of English.
- noun (Elec.) Any device in which an imperfectly conducting contact between pieces of metal or other conductors loosely resting against each other is materially improved in conductivity by the influence of Hertzian waves; -- so called by Sir O. J. Lodge in 1894 on the assumption that the impact of the electic waves caused the loosely connected parts to cohere, or weld together, a condition easily destroyed by tapping. A common form of coherer as used in wireless telegraphy consists of a tube containing filings (usually a pinch of nickel and silver filings in equal parts) between terminal wires or plugs (called conductor plugs).
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun physics A
detector ofradio waves used in very earlyradio receivers
Etymologies
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Examples
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The name coherer comes from the first practical instrument made for this purpose.
Electricity for Boys J. S. Zerbe
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The tube of filings through which the electric current is made to pass in wireless telegraphy is called a coherer signifying that the filings cohere or cling together under the influence of the electric waves.
Marvels of Modern Science Paul Severing
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The instrument for this purpose is called a coherer, in which small particles cohere through the action of the electric waves, and are caused to fall apart mechanically, during the electrical impulses.
Practical Mechanics for Boys J. S. Zerbe
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The further experiment led to the coherer, which is simply a glass or ebonite tube containing metallic filings which connect the two ends of a wire conductor entering the tube.
The Catholic Encyclopedia, Volume 2: Assizes-Browne 1840-1916 1913
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The coherer is the valve, always ready to be turned on.
Traffics and Discoveries Rudyard Kipling 1900
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Yes, he told himself, as he stood there, thoughtfully, as though bound to the spot by some Power not himself, -- yes, consciousness was like that little glass tube which electricians called a coherer, and all his vague impressions and mental-gropings were those disorderly, minute fragments of nickel and silver which only leaped into continuity and order under the shock and impact of those fleet and foreign electric waves, which floated from some sister consciousness aching with its undelivered messages.
Phantom Wires A Novel Arthur Stringer 1912
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The coherer was a little tube of glass not as long as your finger, and smaller than a lead pencil, into each end of which was tightly fitted plugs of silver; the plugs met within a small fraction of an inch in the centre of the tube, and the very small space between the ends of the plugs was filled with silver and nickel dust so fine as to be almost as light as air.
Stories of Inventors The Adventures of Inventors and Engineers Russell Doubleday 1910
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Edouard Branly's invention of the 'coherer', an instrument designed to receive Hertzian waves, was communicated to the British Association at Edinburgh in 1893.
The War in the Air; Vol. 1 The Part played in the Great War by the Royal Air Force Walter Alexander Raleigh 1891
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If an electric discharge was capable of operating a coherer across three thousand miles of ocean, then, certainly, the electric discharges from the wireless station four hundred feet away could produce coherer effects on the bad joints in the vat-wiring.
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When electric waves fall upon this coherer, the mercury coheres to the carbon blocks, and thus forms a bridge for the battery current.
Marvels of Modern Science Paul Severing
chained_bear commented on the word coherer
"...on December 12, 1901, the neatly mustachioed Guglielmo Marconi, his overcoat buttoned against the frigid wind, his Italian leather gloves gleaming like polished mahogany, had set up a condenser and an antenna in the old fever hospital on the cliffs above the St. John's harbor, and had heard, through a black telephone earpiece attached to a glass coherer, the dim signal of the letter "S" transmitted by hertzian waves from Poldhu, Cornwall—2720 wireless kilomters away."
—David Macfarlane, The Danger Tree, 54
May 6, 2008