11.6

**Dead medium: Mechanical TV: Baird Television**

From: kadrey_AT_well.com (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 mztv_AT_bravo.ca.

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.


 * Mechanical TV: Baird Television**

The ROM's Institute of Contemporary Culture in association with the MZTV Museum invites you to join us for an historic demonstration of BAIRD TELEVISION, live at the Royal Ontario Museum, Sunday April 14th, 1996, 1:00pm.

John Logie Baird is the Scottish inventor who obtained the world's first real television picture in his laboratory in October,, and demonstrated it to the British public on January 26, 1926. The image obtained was a small 30-line vertically-scanned red and black image, but it was television. Mechanical television based on Baird's systems dominated international television for the next few years into the early 30's.

The first live public demonstration of a Baird Television system in North America since 1932 will take place in Toronto on Sunday, April 14th. John Logie Baird's son, Professor Malcolm Baird, will give a short speech to commemorate the 70th anniversary of the first public demonstration of television; grandson Iain Baird, who presently works at MZTV, will be in attendance to operate the Televisor.

Mechanical systems of this period are not compatible with today's TV signals. When the MZTV Museum decided to restore this televisor to full operation, the first obstacle was to feed a signal to it that it could receive. We requested the assistance of Peter Yanczer, a modern-day mechanical television enthusiast, author, and technician. He built a mechanical camera that would work on a 30-line system, and connected this camera to the television with cables. The televisor itself needed only minor repairs and lubrication, and has remained workable.

By 1930, a British or West European television enthusiast could buy this televisor for home reception for about 18 pounds. The Baird company was licensed to provide intermittent broadcasts from the BBC transmitters, and at least 3,000 enthusiasts "looked in" to see as well as hear some of Britain's most popular singers and comedians.


 * Mechanical TV: How it works**

The scanning and reproducing discs are similar. Both are mounted on driving motors, and each is punched with a spiral of small holes along the outer edge. The number of holes matches the number of lines of picture definition.

At the transmitter in this mechanical system, the studio is in total darkness. A light emanates from a lamp behind the disc and, projected through the holes set in the spiral on the outer edge, scans the features of the subject's face. The photocell converts these variations in the reflected light into the electric impulses, which, once amplified, can be transmitted by radio waves.

At the receiver, the signal is converted into a sequence of bright flashes by the neon tube. The reproducing disc rotates rapidly in front of this tube, and converts each flash of the lamp into a small element of the image. The rapid speed of the disc makes "persistence of vision" possible for the looker-in.

"Persistence of vision" means that the brain retains an image for one tenth of a second after it is perceived by the eye. The rapid repetition of moving images (in film or television) tricks the brain into perceiving continuous images.