Undated photo of Dr. Goldmark (left) examining the first 33⅓ RPM long-playing record developed. Image from http://pdxretro.com/2015/06/the-lp-record-debuted-on-this-day-in-1948/ .
“In 1930, RCA Victor launched the first commercially-available vinyl long-playing record, marketed as ‘Program Transcription’ discs. These revolutionary discs were designed for playback at 33⅓ rpm and pressed on a 12” diameter flexible plastic disc. In Roland Gelatt’s book The Fabulous Phonograph, the author notes that RCA Victor’s early introduction of a long-play disc was a commercial failure for several reasons including the lack of affordable, reliable consumer playback equipment and consumer wariness during the Great Depression…
“Beginning in 1939, Columbia Records continued development of this technology. Dr. Peter Goldmark and his staff undertook exhaustive efforts to address problems of recording and playing back narrow grooves and developing an inexpensive, reliable consumer playback system. In 1948, the 12” (30 cm) Long Play (LP) 33⅓ rpm microgroove record was introduced by the Columbia Record at a dramatic New York press conference.”
Excerpts from http://www.recordcollectorsguild.org/modules.php?op=modload&name=sections&file=index&req=viewarticle&artid=44&page=1 . Learn more at the link.