The Probert Encyclopaedia of Architecture

LEDGER

In architecture a ledger is a large flat stone, especially one laid over a tomb. The term is also applied to a horizontal piece of timber secured to the uprights and supporting floor timbers, a staircase, scaffolding, or the like. It differs from an intertie in being intended to carry weight.
In scaffolding, a ledger is a primary horizontal member used to tie the scaffolding longitudinally and support the transoms and putlogs.
Research Ledger