EARLY TELEGRAPH APPARATUS,CASELLIS...

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Vintage-Views Antique Prints and Maps :: Antique Prints :: Scientific :: Communications :: EARLY TELEGRAPH APPARATUS,CASELLIS PANTELGRAPH,Hughes Telegraph,Mirror galvanometer, 1894 Original Antique Wood Engraving

EARLY TELEGRAPH APPARATUS,CASELLIS PANTELGRAPH,Hughes Telegraph,Mirror galvanometer, 1894 Original Antique Wood Engraving

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Telegraphy (from the Greek words tele = far and graphein = write) is the long-distance transmission of written messages without physical transport of letters, originally over wire. Radiotelegraphy or wireless telegraphy transmits messages using radio. (A telegraph is a machine for transmitting and receiving messages over long distances, i.e. for telegraphy. The word telegraph alone generally refers to an electrical telegraph.) Wireless telegraphy is also known as CW, for continuous wave (a carrier modulated by on-off keying, as opposed to the earlier radio technique using a spark gap) PRINT SHOWS: - CASELLIS PANTELGRAPH - A mirror galvanometer is a mechanical meter that senses electric current, except that instead of moving a needle, it moves a mirror. The mirror reflects a beam of light, which projects onto a meter, and acts as a long, weightless, massless pointer. In 1826, Johann Christian Poggendorff developed the mirror galvanometer for detecting electric currents. The apparatus is also known as a spot galvanometer after the spot of light produced in some models. Mirror galvanometers were used extensively in scientific instruments before reliable, stable electronic amplifiers were available. The most common uses were as recording equipment for seismometers and submarine cables used for telegraphy. The mirror galvanometer was later improved by William Thomson, later to become Lord Kelvin. He would patent the device in 1858. The Hughes Telegraph - Many people are not aware that Morse didn’t invent the telegraph. What he did was invent a particular form of electromagnetic telegraph – one that was elegantly simple and required little maintenance. He (or rather his assistant Alfred Vail) also developed the Morse code. In the early days of the telegraph there were many other attempts to develop methods of communication by wire, and one of these, the Hughes Telegraph, was especially unusual. What makes the Hughes unique? On the sending side, instead of using a Morse key, the operator uses a piano key – or keyboard, to be more precise. The receiver, instead of marking dots and dashes on a paper strip, actually spells out the text of the message. This was quite unusual for the time. These devices were very popular in France, where there were likely many more piano and harpsichord players than telegraphers. Transmission speed was also much slower than the Morse system and so the Hughes system was eventually replaced by the much simpler (and cheaper) Morse apparatus. Very few survive today.

Published for Joseph Meyer Meyers Konversations

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SKU	0527817k6
Quantity in stock	1 item(s) available
Price:	US$15.00

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