[Milsurplus] voice tubes

[WA5CAB--- via Milsurplus]

It's called the "Engine Order Telegraph".

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480

In a message dated 12/27/2014 22:04:40 PM Central Standard Time, 
garypewitt at centurytel.net writes: 
> Yes there was a whistle in the cap of the voice tube to serve instead of 
> a bell.  When you blew down the tube it announced your call.  It was too 
> noisy in the engine room for a voice tube so they used a semaphore like 
> "telegraph".  You've surely seen them in the movies.