The first television picture had to turn

On September 7, 1927, Philo Farnsworth’s electronic television system transmitted a picture from one room of his San Francisco laboratory to another. The picture was a straight line painted on glass.

This sounds like television with nothing on. It was closer to a good test.

The slide sat between a bright lamp and Farnsworth’s image dissector tube. At the receiver, the line appeared as a luminous mark. Farnsworth then told his brother-in-law Cliff Gardner to rotate the slide. The received line rotated too.

That movement mattered. A stationary streak on an experimental screen could be an accident of the apparatus: electrical noise, a defect in the tube, a reflection, wishful inspection. When a mark in one room followed the deliberate movement of an object in another, the system showed correspondence. The line was not much of a programme, but it was difficult for the machine to fake.

Farnsworth had filed his television patent that January. Its central operation was to form an electrical image, scan its elementary areas, turn their varying intensity into electrical energy, and reproduce the image at the receiver. The patent’s language is more ambitious than a line because the line was never the point. It was a conveniently severe subject: high contrast, simple geometry and an orientation that could be changed visibly.

The Television Academy calls it Farnsworth’s first electronic television image and describes the slide as an early success in the race toward electronic television. Later demonstrations supplied dollar signs and human faces. Those were better publicity.

The line supplied something more basic. Before television could show movement as entertainment, someone had to move the test object and check that the picture obeyed.