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Dead medium: Mechanical Television:Mechanical TV: The General Electric Octagon; the Daven Tri-Standard Scanning Disc; 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
Source(s): 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


Daven Tri-Standard Scanning Disc, 1928


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


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


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


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


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 (