Cross-section of the Langevin loudspeaker atop the Railroad Building at the 1939 New York World's Fair. Consisting essentially of low and high frequency units; the latter with a multi-cellular "honeycomb" for radiating the sound in all directions, the speaker affords excellent distribution over a vertical and horizontal angle of about 70 degrees. Both units are mounted coaxially, avoiding phase difference. The speaker is rated at 50 watts for continuous operation.
I was told these were designed for early stereo
Circa mid 1930's