(((tomj note: I agree with the author, this is on the fringes of 'media'. For technical specifications on an old RCA monoscope, see my web page, http://wps.com/archives/tube-datasheets/Datasheets/RCA-CRPD-105A/30.JPG or http://wps.com/archives/tube-datasheets/Datasheets/RCA-CRPD-105A/index.html for the entire catalog of light- and image-processing vacuum-state technology)))
I remember seeing, when i was quite young (late 60s), the 'indian head' black-and-white test pattern on TV. a quick search of the web produced not only copies of the image along with numerous other TV test patterns from broadcast- ers several countries, but also this snippet about how the image was produced:
Probably the most famous American B&W test pattern is the so-called "Indian Head" monoscope pattern. This pattern was originated by RCA in 1939; it was designed to be generated using a special tube called a monoscope, a CRT which had a metal plate target on which the pat- tern was printed. The black lines of the pattern would interrupt current flow as the pattern was scanned to provide the desired video output. These tubes could only handle black and white - no shades of gray hence they had to be simulated either with a halftone dot pattern or with patterns of fine lines.
a picture of a monoscope of the kind used to generate the image is here.
it's an interesting question which aspect of this (if any) might constitute a dead medium. a masked CRT doesn't seem all that special, and the image itself isn't really a med- ium; but an 'indian head' monoscope seems like it should-- and now that test patterns are no longer a normal feature of broadcasting, maybe they qualify as a genre.