Final answer:
The assistant station supervisor contacts involved stations to coordinate the response to a diversion, similar to how the Underground Railroad used discreet communication to guide freedom seekers.
Step-by-step explanation:
The purpose of an assistant station supervisor contacting the involved stations when there is a diversion in service is to coordinate the response to the diversion. This coordination is crucial for ensuring that each station is aware of changes and can properly assist in managing the diversion. This may include informing employees, requesting assistance, or even reporting to higher authorities if necessary. Within the context of the Underground Railroad, this communication strategy helped maintain operational security and effectiveness. Station masters communicated discretely, often using hidden cues like quilt patterns or song lyrics, to guide freedom seekers from one station to the next without written directions, which could be intercepted.