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Television was not invented by a single inventor, instead many people working together and alone, contributed to the evolution of TV.

1831: Joseph Henry's and Michael Faraday's work with electromagnetism makes possible the era of electronic communication to begin.

1862: Abbe Giovanna Caselli invents his "pantelegraph" and becomes the first person to transmit a still image over wires.

1873: Scientists May and Smith experiment with selenium and light, this opens the door for inventors to transform images into electronic signals.

1876: Boston civil servant George Carey was thinking about complete television systems and in 1877 he put forward drawings for what he called a "selenium camera" that would allow people to "see by electricity." Eugen Goldstein coins the term "cathode rays" to describe the light emitted when an electric current was forced through a vacuum tube.

Late 1870's: Scientists and engineers like Paiva, Figuier, and Senlecq were suggesting alternative designs for "telectroscopes."

1880: Inventors like Bell and Edison theorize about telephone devices that transmit image as well as sound. Bell's photophone used light to transmit sound and he wanted to advance his device for image sending. George Carey builds a rudimentary system with light-sensitive cells.

1881: Sheldon Bidwell experiments with telephotography, another photophone.

1884: Paul Nipkow sends images over wires using a rotating metal disk technology calling it the "electric telescope" with 18 lines of resolution.

1900: At the World's Fair in Paris, the 1st International Congress of Electricity was held, where Russian, Constantin Perskyi made the first known use of the word "television."

Soon after, the momentum shifted from ideas and discussions to physical development of TV systems. Two paths were followed:

Mechanical television - based on Nipkow's rotating disks, and

Electronic television - based on the cathode ray tube work done independently in 1907 by English inventor A.A. Campbell-Swinton and Russian scientist Boris Rosing.

1906: Lee de Forest invents the "Audion" vacuum tube that proved essential to electronics. The Audion was the first tube with the ablity to amplify signals. Boris Rosing combines Nipkow's disk and a cathode ray tube and builds the first working mechanical TV system.

1907: Campbell Swinton and Boris Rosing suggest using cathode ray tubes to transmit images - independent of each other, they both develop electronic scanning methods of reproducing images.

American Charles Jenkins and Scotsman John Baird followed the mechanical model while Philo Farnsworth, working independently in San Francisco, and Russian Ð"©migrÐ"© Vladimir Zworkin, working for Westinghouse and later RCA, advanced the electronic model.

1923: Vladimir Zworykin patents his iconscope a TV camera tube based on Campbell Swinton's ideas. The iconscope, which he called an "electric eye" becomes the cornerstone for further television development. He later develops the kinescope for picture display.

1924 - 1925: American Charles Jenkins and John Baird from Scotland, each demonstrate the mechanical transmissions of images over wire circuits. Photo Left: Jenkin's Radiovisor Model 100 circa 1931, sold as a kit. Baird becomes the first person to transmit moving silhouette images using a mechanical system based on Nipkow's disk. Vladimir Zworykin patents a color television system.

1926: John Baird operates a 30 lines of resolution system at 5 frames per second.

1927: Bell Telephone and the U.S. Department of Commerce conduct the first long distance use of TV, between Washington D.C. and New York City on April 9th. Secretary of Commerce Herbert Hoover commented, "Today we have, in a sense, the transmission of sight for the first time in the world's history. Human genius has now destroyed the impediment of distance in a new respect, and in a manner hitherto unknown." Philo Farnsworth files for a patent on the first complete electronic television system, which he called the Image Dissector.

1928: The Federal Radio Commission issues the first television license (W3XK) to Charles Jenkins.

1929: Vladimir Zworykin demonstrates the first practical electronic system for both the transmission and reception of images using his new kinescope tube. John Baird opens the first TV studio, however, the image quality was poor.

1930: Charles Jenkins broadcasts the first TV commercial. The BBC begins regular TV transmissions.

1933: Iowa State University (W9XK) starts broadcasting twice weekly television programs in cooperation with radio station WSUI.

1936: About 200 hundred television sets are in use world-wide. The introduction of coaxial cable, which is a pure copper or copper-coated wire surrounded by insulation and an aluminum covering. These cables were and are used to transmit television, telephone and data signals. The 1st "experimental" coaxial cable lines were laid by AT&T between New York and Philadelphia in 1936. The first "regular" installation connected Minneapolis and Stevens Point, WI in 1941. The original L1 coaxial-cable system could carry 480 telephone conversations or one television program. By the 1970's, L5 systems could carry 132,000 calls or more than 200 television programs.

1937: CBS begins TV development. The BBC begins high definition broadcasts in London. Brothers and Stanford researchers Russell and Sigurd Varian introduced the Klystron in. A Klystron is a high-frequency amplifier for generating microwaves. It is considered the technology that makes UHF-TV possible because it



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