Of course the expression "top of the hour" is shorthand for the moment the second-hand and minute hands of an analog clock point straight up toward the number "12"; the instant a new hour begins. Digital clocks do not have tops on hours.
In broadcasting the 'top of the hour' has come to mean several things. It is the moment that network news is heard, the time when FCC station identification is required (but not for part 15 stations), and the change of shifts for station staff. But how did it get started? I was there, and remember it well.
Back then, oh, maybe around 1895, wire communication had come into common use and telegraph messages could be sent over many miles of wire. Someone invented the telephone and voice communication could be sent over the same wires. At first people went to the telegraph office to send messages which reached their final destination by a bicycle courier, but soon individual homes were getting hookups for personal phoning and many bicycle jobs were lost.
During that period some of us were talking about sending news and music over the wires during intervals when they weren't being used for messaging, and I was involved in one experiment where I played cylinders into a phone-set to 10 or 20 "party-line" listeners and I spoke between musical numbers and described the weather outside the window. This made me the first disc jockey, but the experiment flopped because we couldn't find a way of attaching to many customer lines each being capable of switching over to private calling.
The next day I read in a newspaper that experiments were being done with wireless communication which was expected to completely eliminate the use of wire. I did not like the sound of it and felt threatened. I had not given up on making mass-wire the dominant communications medium and still believe it could have happened if other people weren't all stupid and silly.
Now, what was the original point. I remember. We were leading up to the reason "top of the hour" became a central catch-phrase in broadcasting. But right now I have a banana and fresh cup of coffee, so we'll be back with Part Two.
Awaiting part 2. Interesting.
Back for Part Two "The Top of the Hour".
Now mostly forgotten, there was a bit of a clash at first between those of us already invested in expansion of wire to connect everybody and everything, we felt threatened by the new upstart "wireless invention" which we thought would eliminate wire. But at the same time I myself was fascinated by the idea of wireless communication, so I took both sides of the argument: I was for it and against it. I began thinking of ways to fuse the two; to make them both work together. I envisioned a radio network using wire to get one program to many radio stations, and I recommended network program origination from New York City because people are impressed by tall buildings which give an authoritative branding, but the protagonists felt that "people from the east" were mistrusted because they are fancy. When we got the network started the first thing New York did was put the Philharmonic Orchestra on the air. That was a big turn off in Kansas City and Omaha. But the deep voiced news readers sounded like they knew more than the farm hands on local radio in the midwest and network news sounded like "better" news. So we had combined wired with wireless, but there was mass uncertainty over just when the news would be read on the network wire. The presenters in New York took to the air when they had something to report, but local stations didn't know when to switch over to network and often missed the first few minutes of the news or tuned in when nothing was being sent. What we needed was some kind of coordination.
Late one evening it came to me. Self-winding clocks. Ya. Big mechanical clocks at every radio station that would wind themselves and get reset by pulses coming over a wire, but the phone company was aloof and didn't want to consider what they called a hair-brained idea. So we took it to Western Union that was struggling to stay afloat since their text messaging was being phased out since the voice telephone took over, and they made it happen. By common agreement the news from New York would be sent over the network wire exactly when the minute-hand and second hand pointed to the top of the hour.
Western Union Self Winding Clock for General Industry
Western Union Self Winding Clock for Radio Stations
CORRECTION
In Part Two of "Top of the Hour", about midway into it, I inadvertently said "protagonists" when I meant "antagonists".