I last worked with edge lights almost 70 years ago. The lights had to be masked with masking tape so that the light fell on the edge of the mosaic. My aging memory says it had something to do with electrons fallng back on the mosaic.
Some one asked about 485 Madison Ave a while back.
The main radio facilities including master control were located on the 21st and 22nd floors. There was a news studio on the 17th floor where Tony Marvin could be seen from the elevator lobby doing the “world news roundup” (1940). All other radio facilities including the studio building (49 E.52nd) were off premise.
Thanks to Hal Deppe for stirring the pot. It's great to know there are still old timers around. Let''s hear from more even it it is only to say hello.