My first job out of high school was with Canadian National Railways where I was trained and worked as a Telegraph Operator. They had just phased out use of the telegraph and were then relying on teletype and Telex machines as well as phones.
Back then, railroads operated on single track and needed telegraph operators to pass on dispatchers train orders so they would know where to meet trains coming the other way and who had to take the siding.
Train orders were dictated over the dispatchers phone (a direct phone line system) to operators like me who would write them down and then verbally repeat them back to the dispatcher to ensure accuracy. They were either a 19Y or 19R order. 19Y meant they could pick up orders on the fly while 19R meant they had to come to a full stop.
The train crews knew if a station had orders by the train order signal which was either green, yellow or red. These signals were also known as train order boards and were manually controlled from inside the station by an operator.
If a station had no orders, the signal was green with the train order board straight up and a green light. If the operator had 19R orders, the signal was straight out and the train had to come to a dead stop at the station to receive orders.
If the operator had 19Y orders, the train could slow down instead of stopping and the operator would stand outside with a train order hoop so one of the train crew could stick his arm out and get the written orders from the hoop.
This was referred to as hooping up the orders. You had to stand extremely close to the train as it passed and a second duplicate set had to be hooped up to the tail end crew as well. On a hundred car freight train, by the time the caboose got to me, that train was moving about fifty miles an hour. Pretty scary because there was always a chance that steel strapping securing cargo might come loose and could seriously injure or decapitate someone. Of course, when I was eighteen or nineteen, that possibility never fazed me.
When hooping trains first began, they used bamboo shaped into a hoop onto which the train orders were clipped. Train crews would grab the whole hoop, remove the orders, then toss the hoop on the ground. Operators would have to walk down the track to retrieve them. A real pain.
Someone came up with a better idea. Why not just have the crew take the orders tied to string? No hoops to retrieve then.
The picture below shows first hoops used on the left, then the string method on the right
Life Unfolding 