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Subject: Dead Media Working Note 11.7

Dead medium: Mechanical TV: The General Electric Octagon; the Daven Tri-Standard Scanning Disc; the Jenkins W1IM Radiovisor Kit, the Jenkins Model 202 Radiovisor, Jenkins Radio Movies; the Baird Televisor Plessey Model, the Baird Televisor Kit; the Western Television Corporation Visionette

From: (Richard Kadrey)

These are excerpts from the catalog from the exhibition at the Royal Ontario Museum, "Watching TV". The exhibition runs through September 15, 1996.

The catalogue is available from Royal Ontario Museum shops, CityStore 299 Queen Street, West, Ontario, Canada or from MZTV Museum. Cost - $11.50 Cdn., $10.00 US, plus shipping. Send email orders to

Credits: An excerpt from "Watching TV: Opening the Doors of Reception" by Liss Jeffrey, Acting Director, MZTV Museum. Technical research by Gary Borton, Consulting Curator, and Iain Baird, Researcher, MZTV Museum.

The General Electric Octagon, 1928 (U.S.A.) with RCA radio 1928 (U.S.A.)

This mechanical television receiver was built for a 48- line television system developed during 1927 by Ernst W. Alexanderson, who was the Chief Consulting Engineer at the GE laboratories in Schenectady, New York. An elaborate experimental transmission on this type of receiver was internationally recognized as the first television drama. Entitled "The Queen's Messenger", the play had two characters, with only the heads or the hands of the four actors visible at any one time. Two actors spoke the lines, while the other two acted as "hand models".

The transmitted signal was received on a console radio and monitored through the 3" lens on the Octagon by the director, and the actors were only a few feet away. GE considered mass-production of the Octagons, but this never materialized.

Daven Tri-Standard Scanning Disc, 1928 (U.S.A.)

The lack of a common standard of picture definition contributed to the demise of the mechanical television boom of the late 1920's and early 1930's. One solution was to make a television set that could receive a number of different standards. This Daven unit was based on a large 24" disc capable of scanning three different standards of picture definition, 24-line, 36-line and 48-line, enabling the viewer to receive more stations.

The television signal was received by a short-wave radio. The operator then had to adjust the height of the neon lamp to match the correct spiral of holes, and synchronize the rotation of the scanning disc to the corresponding rotations per minute. The tiny picture would be visible in one of the three frames (marked within the black outline).

Homebrew W1IM Scanning Disc, 1928 (U.S.A.)

This home-made scanning disc television unit was built by the Connecticut radio experimenter, Clifford Fraser, using hand-written instructions sent to him by the mechanical television pioneer and broadcaster, Charles Jenkins.

Jenkins was aware that "Radiovision" was in its infancy and actively encouraged involvement, experimentation and the exchange of information within the amateur radio community. In the late 1920's, he even went so far as to offer Radiovisor Kits similar to this one at $7.50 U.S. postage paid - a price so low that it meant a loss for his company.

Jenkins Model 202 Radiovisor, 1929 (U.S.A.)

This mechanical scanning-drum unit was engineered, designed and manufactured by the Jenkins Television Corporation, a company founded in 1928 by the American television pioneer, Charles Francis Jenkins. As early as 1894, he presented an article in the periodical, Electrical Engineer, on a method of electrically transmitting pictures. He was one of the earliest to succeed at television transmission, and claimed to have executed the first reported transmission of television by radio in 1923.

Hugo Gernsback of Radio News and Watson Davis of Popular Radio witnessed a demonstration in the same year. In 1928 Jenkins announced the birth of a new entertainment industry, "Radio Movies". Shortly thereafter, Jenkins Laboratories Incorporated initiated 48-line silhouette broadcasting through regularly scheduled telecasts over station W3XK and a few other stations that showed "Radio Movies". Jenkins preferred the term "Radiovision" to "Television", which explains this unit's name.

Baird Televisor, 1930 (U.S.A.)

The Plessey model was the most popular version of the mechanical "Televisor" to be available to the British and West European retail buying public. It was engineered and designed by John Logie Baird and manufactured by the Plessey company in England. It was purchased by television enthusiasts to watch the periodic Baird Studios/BBC broadcasts available from 1929 to 1932. The 30 line images did not take up the entire "screen," but were in fact 6cm high and 2cm wide. Instead of black and white, they were black and red due to the colour of the neon gas in the lamp.

About 1,000 of these sets were originally produced and priced at just over 18 British pounds each. There were kit receivers without the tin cabinet, available from Baird's for only 7 pounds. Baird was one of the true pioneers of television. He successfully demonstrated the possibilities of the Nipkow system of mechanical television by achieving the first television picture in October, 1925.

Western Television Corporation Visionette, 1932 (U.S.A.)

Western Television Corporation played a significant role in the evolution of television in North America. Canada's first experimental television station, which was operated by the Montreal newspaper La Presse and radio station CKAC, was supplied with Western Television equipment. The Canadian public witnessed Western Television's technology through a special mechanical projection apparatus, which was demonstrated at Eaton's and department stores in Toronto, Montreal and Winnipeg during 1933.

In the U.S., Western's travelling demonstrations included a 9-day run at Macy's in New York that was witnessed by over 200,000 people.

The Western Television Corporation drew on the talents of television pioneer Ulysses A. Sanabria, who is known for his use of interlaced scanning. Interlacing improved picture quality by reducing flicker. This television utilizes an interlaced aluminum scanning wheel and 3" magnifying lens. It was among the last and most advanced mechanical home televisions to be in use before the electronic sets began to show greater promise.

Richard Kadrey (

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