[0x0]

Why did he need a fast horse? Couldn't he have done the first withdrawal just after the books went out the door at one branch, then calmly gone over to the other branch for the 2nd withdrawal? No need to race the books, if the book transfer interval was only every few hours?

[Terr_]

Dunno, but it could be explained if the bank already had a time-restriction to cover the time between regular transmissions, but not the time of the transmission itself.