Blattnerphone steel tape recorder, an early magnetic recording technology, developed by Dr. Kurt Stille and Louis Blattner in 1924, at BBC studios, used to record programs for rebroadcast in Empire countries. The recording tape was 3mm wide and 0.08 mm thick, and traveled at 1.5 meters / second. It was limited to voice programs as it did not have the fidelity to record music. Caption: ""One of the Blattnerphone BBC recording machines on which the programs are recorded by a magnetic process for Empire broadcasting""