© Copyright 2001 Johnson-Shaw Stereoscopic Museum
37804 A Radio Transcription Recorder.
   Here is where recordings, called transcriptions, of radio programs are made.  Transcription recorders are very expensive instruments.  They must be very carefully made and operated, as a mistake of even one one-thousandth part of an inch would cause poor recording.
   The operator is looking though a microscope at the groove being cut in the record and is adjusting it with his right hand.  The groove looks like a groove in a regular phonograph record.
   Transcriptions do not turn so fast as phonograph records.  They turn only thirty-three and one-third times around in a minute, called revolutions per minute, which is shortened to R.P.M.  A phonograph record turns seventy eight R.P.M.  Because they turn only thirty-three and one-third R.P.M. and are sixteen inches across, as much as fifteen minutes of news, music or drama can be put on one transcription.  It would take six ordinary phonograph records to play the same length of time.

Click on image to view in 3D.  Glasses needed.