(but specified on the label by a letter from A to D) rather than revolutions per minute. If the sound quality near the label of an ordinary record was considered acceptable, then playing time could be greatly increased by using that same groove-to-needle velocity throughout the recording. This is known as the CLV (constant linear velocity) format, as opposed to the usual CAV (constant angular velocity) format. The World Record Controller was an attachment for ordinary record players that slowed the turntable down when playing the outside of the record and allowed it to gradually speed up as the needle was carried inward by the groove. Of course, only special World records could be used. The World system was a commercial failure. The principle, first proposed in a fundamental U.S. sound recording patent in 1886, was briefly revived in 1939–1940 for the unusual "Cinematone Penny Phono" jukebox (price to play one selection: one cent), which used it to squeeze ten short recordings of current pop songs onto each side of one 12-inch record. Compact discs and DVDs use the CLV format to make efficient use of their surface areas. The CLV format would reemerge in the 1940s and 1950s in office dictation machines known as the Gray Audograph and the CGS/Memovox, which combined it with the flexible-disc format and the inside-out recording format used by CDs today. Both machines recorded at a fixed pitch, but the Grey Audograph could only record at one linear speed allowing 15 minutes per side of a 7-inch disc. The CGS or Memovox, on the other hand, had a High Fidelity speed as well as a Speech speed, allowing over two hours of recording time per side on a 12-inch disc. In the 1970s, Atlantic Records started producing a series of albums later designated on a label known as Syntonic Research. Each album consisted of two full-side tracks, usually at least half an hour long per side, of sounds recorded of various locations. For example, one side would have ocean waves crashing against the shore and the other would have the sounds of birds chattering away in an aviary; another record might have frogs, crickets and birds making their usual vocalizations that were heard in the early morning hours of a swamp or lake. There were a few dozen made. These were mostly used for soundscape or relaxation purposes. The first album in the series