To us here in the Twenty-first century, the idea of "mechanical" television sounds almost absurd -- how could television ever have been anything but electronic? Nevertheless, the principle is amazingly simple, so much so that it would be fairly easy to tinker up a television in your garage today.  The basic element of such systems is the Nipkow Disk, invented in the 1880's by Paul Nipkow.  When we think of the classic television screen of the pre-HDTV era, we of course think of lines, each line containing some information about color and shade, each refreshed and compiled to create the illusion of a moving picture.  Nipkow's disc did the same thing, only mechanically: on a disc of metal, tiny pinholes were drilled in a gradual spiral, such that each was just a bit further in from the edge, and a bit further (the size of one frame of the image) along the perimeter.  As the disc spins, each pinhole passes by (or "scans") one vertical line; when assembled, the lines form a picture, which is refreshed each time the disc completes a rotation.  For the effect of motion, the frame rate must be high -- at least 12 and preferably 20 or more frames per second; some discs used two sets of slightly offset pinholes to produce a better image with fewer rotations.

The Nipkow disc had been around for decades when Baird began his work on television in the early 1920's.  Though the principle was sound, the problem lay in converting and amplifying the disc's scan signal, which required a light-sensitive material.  Selenium, an ideal choice, posed problems because it was slow to respond to changes, and its signal output was very low.  The invention of electronic amplification using valves (or "tubes" as they were commonly known in the US) solved half of the problem, and so Baird worked on the second.  The use of very bright lights, and replacing the disc's pinholes with lenses, helped, but only enough to produce so-called "shadowgrams" of brightly back-illuminated cutouts.  To get a signal from reflected light -- the kind of light that a human face emits -- took considerable work.  The exact nature of Baird's solution is still something of a mystery, but apparently involved the application of a carefully-calibrated boosting signal at the same frequency as that of the signal from the photocell.  In March of 1925, he made a series of public demonstrations at Selfridge's department store on Oxford Street; By the fall of that year, he was close enough that he considered making a more formal demonstration in front of recognized experts.

Baird conducted his final experiments in a tiny top-floor apartment on Frith Street in London's Soho district. On October 2, 1925, he succeeded in transmitting in his laboratory the first television picture with shades of grey derived from reflected light: the head of a ventriloquist's dummy known affectionately as "Stookie Bill", in a 30-line vertically scanned image. Baird later transmitted the image of a young man working in the office downstairs, William Taynton, whom he paid two shillings and sixpence to endure the hot lights then necessary for an effective image.

Baird repeated the transmission for members of the Royal Institution and a reporter from The Times on January 26, 1926 in his laboratory at 22 Frith Street in the Soho district of London. It was the world's first demonstration of a true television system, one that could broadcast moving images with tone graduation. In 1928 he demonstrated the first colour television and true stereoscopic television, ad that same year he developed Phonovision, a method of recording his television signal on a phonograph record.  A few of his test recordings have survived and, restored by engineer Don McLean, give us a remarkable window into television as it worked in the late 1920's.

The successful demonstrations enabled Baird to raise money from investors, hire a staff of engineers, and move to a much larger facility at Long Acre.  There, he was able to secure the grudging agreement of the BBC to allow him to transmit regular broadcasts, though only on a less-than-ideal bandwidth, and only very late at night.  Sir John Reith, head of the BBC, believed that television was a "waste of time," and conceived of the limited service provided as purely experimental.  Nevertheless, with the support of the government, Baird's company eventually obtained a license for regular broadcasts, and began the sale of receivers, known as "televisors."  These came assembled or as a less-expensive kit, and included an application form for a license (British broadcasting at this point was strictly noncommercial, and subsidized by license fees charged to receive its signal). 

Throughout the early 1930's hundreds of "lookers-in" used their sets to receive these early broadcasts, which used a 30-line system.  Although limited in scope, continual technical improvements gave these broadcasts a remarkably clear picture for its size.  In 1930, the BBC broadcast the first ever television drama, an adaptation of Luigi Pirandello's "The Man with the Flower in his Mouth."  Despite these successes, the Baird company -- which depended on televisor sales for its only revenue, and had to pay the BBC for its transmissions -- was losing money quite rapidly.  An attempt by Baird to obtain licenses in the United States from the Federal Radio Commission was quashed by Westinghouse and other radio broadcasters, who were developing their own mechano-electrical systems The 30-line broadcasts were discontinued in 1934, and a new "Television Committee," headed by Lord Selsdon, was established to determine the next steps.  The company was re-organized, and was eventually purchased by Isidore Ostrer, who was also the owner of the Gaumont-British film and cinema chain.  Baird was removed from day-to-day management, although the company continued to provide staff and materials for his private laboratory.

In the wake of the Selsdon Committee's recommendation that mechanical and electronic systems be tried, the  Baird company was forced to compete with the newly-created firm of Marconi-EMI, who had developed an all-electronic camera, the Emitron.  At the time, the Emitron still suffered from dropouts and distortions, and the outcome was by no means definite.  By that time, Baird's had switched to an "intermediate-film" system where scenes were shot on cinema film which was immediately developed and scanned electronically.  When the BBC's new higher-definition system was inaugurated in the fall of 1936, the two systems were run on alternate days.  EMI's technicians made significant improvements in their system, while Baird's reached a plateau without being able to reduce problems such as the limited motion of their cameras and leaks of developing fluid.  The fire at the Crystal Palace in November of 1936 was a further blow, as it destroyed their laboratories and much of their equipment.  Early in 1937, the BBC chose EMI as the standard, and the Baird system was discontinued.

Baird's Final Years

Baird ended up losing most of the money he'd made through television, and when the firm bearing his name went into receivership, he lost the services of its technicians.  Nevertheless, he continued his researches at his own expense; having long ago realized that electronic systems were the way of the future, he managed to develop a high-resolution color electronic system that had better resolution than any commercial system of its day.  Unfortunately, the years during and just after the war proved to be difficult economic times, and there was no interest from investors in something which consumers would be unable to afford.  Baird died on June 14th, 1946, having brought into the world what would be one of the most important and widespread technologies of the twentieth century.

There were two other inventors who have a claim on the "first," or at least on very early television: Philo T. Farnsworth and Charles Francis Jenkins.  If one defines television as the transmission of any sort of moving image -- even a silhouette --  by wire or wireless, Jenkins is only a few months behind Baird, and Farnsworth's out of the running.  If you define it as the transmission of an image made from reflected light, Baird stands alone.  If, on the other hand, you define it as the invention of a fully electronic system for the transmission of images -- which, after all, was to be the ultimate mode of transmission for the rest of the twentieth century, then Farnsworth stands alone.

Farnsworth's system was electronic from the beginning, and he developed several key patents which even the giant RCA could not get around.  Getting a recognizable image of the human face proved a challenge; Baird was already transmitting television across the Atlantic at the time when Farnsworth's system was only capable of sending simple images such as a vertical line or a dollar sign.  Farnsworth eventually developed a complete system, with both a camera tube -- which he dubbed the "Image Dissector" -- and a picture tube.  The Dissector proved the harder to perfect; Farnsworth actually licensed the technology to Baird's in 1935, but it was still not sensitive enough for a direct camera. Baird's instead used it as part of their intermediate film system.  In the end, the war defeated Farnsworth as it had Baird; RCA simply waited for his patents to expire, and then used their far greater financial resources to steamroller over his system.

On June 13, 1925 -- scarcely three months after Baird's demonstration at Selfridge's -- Charles Francis Jenkins was able to demonstrate the transmission of the silhouette image of a toy windmill in motion from a naval radio station to his laboratory in Washington, using a lensed disk scanner with 48 lines per picture, 16 pictures per second. At this early date, low definition silhouettes were the best Jenkins could do, since his bandwidth was limited to 10kHz, but he later obtained permission from the Federal Radio Commission to move to a carrier frequency of 4.95 MHz with a bandwidth of 100 kHz. Jenkins employed a rotating mirror drum rather than a Nipkow disc, in his receivers (drum receivers were later used by Baird as well). The sets were only able to pick up Jenkins's own experimental signal, transmitted from his station W3XK in Wheaton, Maryland; the demand for receivers -- which Jenkins called "radiovisors" -- never reached a profitable level.