Today is the 86th Anniversary of Herbert Hoover (Secretary of Commerce at the time) making a video phone call from Washington DC to New York on the AT&T mechanical TV scanner.

http://www.corp.att.com/history/television/

http://www.earlytelevision.org/bell_labs.html

Looks like about 50 scanning lines (assuming they were horizontal).
Does anyone know the actual count?

That is really amazing. That Bell set is essentially a mechanical Plasma TV!