Telegraphing around a derailment

These are questions about the the days of telegraph only. If a train derailed and took out the telegraph line, how did communications get from dispatcher to operators on the other side of the wreck? Could the railroad get connecting RR's to instantaneously rig a dedicated line for them? Did the RR have to use Western Union? If Western Union, were there priority messages in the 1890's? Did the DS orders go through Western Union, or were they copied and repeated by a Western Union man?

In many cases, the railroad's telegraph lines were also Western Union telegraph lines, both sharing the same poles.

If the wires were knocked down, the signal and communications department got them up and running posthaste.

This is speculation. In the era you speak of, the larger railroads such as NYC often had branch lines parallel with the main. I believe upon instruction, operators on a given line could plug in circuits to connect other wires. So if for example a wreck wiped out the wires at Clyde NY, the DS might use the wires for the parallel Auburn Road to bypass it, and have the ops on the other side plug back in to reach the desired stations. Again, not speaking from cold hard proof, just a semi-educated guess.

Yes, that too. Under the old systems, many things were possible that couldn't be done today due to progress. The old crank-and-cuss phone system had advantages over newer Centrex systems, but also had disadvantages. Progress is a double-edged sword.

BR&P you're correct...they were called patch cords. Every office had several. The primary use was to establish an extended block with the phone/telegraph system when a part time office was closed. They could and were used for the purpose you indicate.