groove and had a locked groove at the outer edge. Some radio transcription discs had both outside and inside-start as a way to maintain the fidelity levels when the record was turned over. Inventor Thomas Edison, who always favored the cylinder for all its advantages, also cut his discs with vertically modulated grooves from their introduction in 1912 until a year or two before his company's demise in 1929 (Edison Disc Records). Edison pioneered fine groove discs that played for up to five minutes per 10-inch side; they were very thick to remain perfectly flat and played back with a precision-ground diamond stylus. A commercially unsuccessful extension of the system introduced grooves nearly twice as fine as those of microgroove LPs, yielding playing times of up to 20 minutes per side at 80 rpm and again requiring a special diamond stylus. Even more than with Pathé discs, Edison's vertical-cut records called for specially designed equipment for playback. When using a modern stereo cartridge to play these or other vertical-cut monophonic recordings, the polarity of one channel must be inverted at some point before the two channels are combined to produce a mono signal, as is desirable; otherwise, they largely cancel each other out, leaving little more than surface noise audible. In 1977, Mercury Records released a pair of dealer-only promotional LPs called Counter-Revolutions (samplers of various Mercury popular artists at the time) which played from the inside-out and had a locking groove at the disc's edge. In 1984, Many Records in Italy released an Italo disco song named "Back To Zero" by Francis Lowe that played from the edge of the label outwards on side B, and normally on side A. In 1985, Memory Records in Germany released a limited-edition version of the Italo disco hit "Talking to the Night" by Brian Ice that played from the edge of the label outwards. In 1993, American metal band Megadeth released a single "Sweating Bullets," on 12-inch blue vinyl with both sides running from the inside of the disc outwards. In 1994, the Cyrus 12-inch single "Inversion" released by Basic Channel had one side that played inside out. In 1997, English Sound Artist Janek Schaefer released his first ever record, "His Master's Voices" a transparent two sided LP. Both sides play from the inside to the outside of the disc. In 1998, American hardcore punk band Dropdead released their second untitled album,