File:Guglielmo Marconi posing.jpg

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Original file(3,118 × 3,461 pixels, file size: 3 MB, MIME type: image/jpeg)
Description
English: A publicity photo of Italian radio pioneer Guglielmo Marconi posing in front of his early radio apparatus. The device at left is the transmitter, consisting of a Righi spark gap dipole antenna (balls) which is powered by high voltage from an induction coil (not visible). When sparks jump between the central metal balls, radio frequency oscillating currents are excited in the metal rod antenna, radiating radio waves. The device on the right is the receiver. It uses a primitive radio wave detector called a coherer (in box). When a radio wave from the transmitter strikes the coherer it becomes conductive. The coherer applies a pulse of DC current from a battery through a second circuit attached to the coherer to the mechanism at top, a telegraph sounder, creating a "click" sound. Information can be transmitted by turning the transmitter on and off rapidly with a switch called a telegraph key, spelling out messages in Morse code. The message can be translated from the series of clicks produced by the receiver. This early transmitter radiated radio waves at UHF frequencies, and its range was limited to a few hundred feet. Creator/Photographer: Unidentified.

Medium: Medium unknown

Dimensions: 21.9 cm x 19.7 cm

Date: prior to 1937

Collection: Scientific Identity: Portraits from the Dibner Library of the History of Science and Technology - As a supplement to the Dibner Library for the History of Science and Technology's collection of written works by scientists, engineers, natural philosophers, and inventors, the library also has a collection of thousands of portraits of these individuals. The portraits come in a variety of formats: drawings, woodcuts, engravings, paintings, and photographs, all collected by donor Bern Dibner. Presented here are a few photos from the collection, from the late 19th and early 20th century.

Persistent URL: [1]

Repository: Smithsonian Institution Libraries


Accession number: SIL14-M001-13

Date before 1937
date QS:P,+1937-00-00T00:00:00Z/7,P1326,+1937-00-00T00:00:00Z/9
Source Portrait of Guglielmo Marconi (1874-1937), Engineer and Physicist
Author Unidentified photographer. Smithsonian Institution from United States
Permission
(Reusing this file)

http://www.si.edu/copyright/

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Date/TimeThumbnailDimensionsUserComment
current19:50, 3 April 2016Thumbnail for version as of 19:50, 3 April 20163,118 × 3,461 (3 MB)Wdwd (talk | contribs)gamma correction, contrast
13:32, 25 May 2009Thumbnail for version as of 13:32, 25 May 20093,118 × 3,461 (2.24 MB)Lobo (talk | contribs){{Information |Description= '''Creator/Photographer''': Unidentified photographer '''Medium''': Medium unknown '''Dimensions''': 21.9 cm x 19.7 cm '''Date''': prior to 1937 '''Collection''': [http://www.sil.si.edu/digitalcollections/hst/scientific-ide
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