In "An Occurrence At Owl Creek Bridge," what was the method used to hang Peyton Farquhar?

Peyton's
execution is staged at the center of a covered railroad trestle that spans Owl Creek. The train
tracks are laid on top of railroad ties that make up the floor of the bridge. There are open
spaces between the ties. If you were to step into one of these spaces, you would fall into the
water below. 

The rope used to hang Peyton is tied to a timber over his head
in the bridge's covering. A plank is laid across one of the railroad ties with each end of it
hanging over spaces in the floor of the bridge. Payton stands with the rope around his neck on
one end of the plank. A sergeant stands on the other end of the plank to balance it. At the end
of Part I, the sergeant "steps aside," which causes Peyton's body, on the other end of
the plank, to fall through the opening on the floor of the bridge. His body falls straight down,
hitting the end of the rope, and breaking his neck.

Executing Peyton is no
casual affair. His hanging is carried out with formal military ceremony, precision, and a
certain kind of respect:

Death is a dignitary who when he
comes announced is to be received with formal manifestations of respect, even by those most
familiar with him. In the code of military etiquette silence and fixity are forms of
deference.

Peyton was hanged in a very civilized manner,
according to strict military procedure--not that these circumstances gave him any comfort before
he died.