Technology History | 202 Green Street — The First Electronic Picture Was One Straight Line

The plaque on the corner of Sansome and Green calls him the Genius of Green Street, which is the kind of thing a plaque says, and then gives a date worth defending: 7 September 1927.

Philo Farnsworth was twenty-one. He had a loft here, a $25,000 investment from a San Francisco bank, his wife Pem, her brother Cliff Gardner blowing the glass, and two other assistants.

What they transmitted from one room to the next was a single straight line, scratched on a glass slide and lit by a carbon arc lamp.

The apparatus was the image dissector, a tube that scanned with a beam of electrons instead of a spinning disc with holes in it. Nothing in the picture path moved.

Some accounts print 27 September. The state landmark register, the Television Academy and the plaque on this corner all say the seventh, and the twenty-seventh should be treated as a slip.

The rest of his working life went on proving he had been here first. RCA brought a patent interference action, the patent office decided for Farnsworth in February 1935, partly on a sketch his high-school chemistry teacher had kept since 1922, and RCA appealed in 1936 and lost.

RCA agreed to pay him royalties in 1939, reportedly the first time it had ever agreed to pay anyone, and then presented television to the public at the World's Fair as its own.

His tube travelled further than his name did. Baird Television in London licensed the image dissector, so when the BBC's rival systems went on air from Alexandra Palace in November 1936, Farnsworth's electronics were inside the British mechanical entrant.

The loft is gone. What marks the site is California Historical Landmark 941, registered on 19 February 1971, a few weeks before Farnsworth died that March; the bronze plate itself was placed in September 1981.

Photo: Almonroth, CC BY-SA 3.0, via Wikimedia Commons