How do you think that book got on top of that electrical(?) box in between two subway tracks?
My first thought is that someone dropped their book onto the tracks while waiting for the train and gave up on it. Later, someone from the MTA was in the tracks cleaning something up or working on something, found it, and instead of throwing it out, picked it up to give away or read later. However, if that was the case, wouldn’t they place the book on the platform rather than on that rather inaccessible box?
My new theory is that a track worker was using that book, either as a log book or as a reference guide, placed it there while they needed two hands for something, and forgot it was there.
Update: The book has disappeared.