Transcription records are quite a special class of recorded materials with the majority of the public not being aware of what they are. Their primary use was in cinemas as a sound source for the "Talkies" at the start, with their use latterly expanded to include a means for recording auditions and interviews for radio stations and other markets. Latterly transcription discs were used as a means of mass programme distribution, between radio networks and individual radio stations and this use continued until tape recordings and programme circuit lines became more commonplace.
To the average member of the public and record collector alike, transcription records are probably best thought of as "big records" if at all seen and recognised since many of them are 16 inches (a few were larger, some were smaller) but 16 inch and latterly 12 inch discs were generally the de facto standard.
Not all transcription records are equal as despite them sharing the same appearance and external format they were often constructed of materials other than vinyl, such as aluminium and even glass. Due to wartime constraints and general fragility therefore many recordings were lost as materials were reused for the war effort or damaged through the rigours of time.
Quite soon after World War II the end was nigh for the heyday of transcription records and by the 1950s their use had effectively ended. A few broadcasters and programme providers, such as the BBC, continued to use vinyl records, cassettes, tapes and compact discs over time but the larger format 16" transcription record was consigned to history. The term transcription recording lives on, however, with more modern formats but generally this indicates a specific release of recording by a broadcaster (in the same vein as director's cut in the video world).
Musiclibrary.fi maintains a large collection of transcription records and access will be provided to its transcription record catalogues in the future.