Sam tells us that the name of the town they chose for their kidnapping venture was Summit. O. Henry had a reason for choosing that name. He wanted to be able to describe the topography. Sam explains that it is stupid to call such a town Summit because the whole region is completely flat. As Sam says:
There was a town down there, as flat as a flannel-cake, and called Summit, of course.
The fact that the area is flat fits in with the half-baked kidnapping plan. Sam sends a letter to the "victim's" father telling him he must leave the $1500 in ransom money under a certain tree. If Ebenezer Dorset and the local law-enforcement officials decided to entrap the kidnapper when he went to pick up the money, they would have to hide at some distance and keep a lookout on that tree. As Sam explains:
The tree under which the answer was to be left—and the money later on—was close to the road fence with big, bare fields on all sides. If a gang of constables should be watching for any one to come for the note they could see him a long way off crossing the fields or in the road. But no, sirree! At half-past eight I was up in that tree as well hidden as a tree toad, waiting for the messenger to arrive.
Sam is already up in the designated tree long before the boy delivers Ebenezer's message. From that vantage point Sam can survey the entire landscape and see if there is any stakeout. If so, he can wait until it is totally dark and make his getaway in a direction away from the lurking lawmen. Sam has to be sure there is no entrapment scheme, because he has given Ebenezer Dorset until midnight to gather the cash and leave the package at the same tree. That means Sam will have to come back again, assuming Dorset agrees to pay the money. By that time Sam should know whether it is safe to come back or whether Ebenezer Dorset was double-crossing them.