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Webster 1828 Edition

ppr.

Supporting by something beneath.

propping

propping ‎(plural proppings)

The act by which something is propped.
- 1904, Kellogg Durland, Among the Fife Miners (page 62)
  By certain arrangements in the former method the miner not only gets the coal but makes all proppings and repairs, so that the face moves much more slowly than with the other method where the hewers devote all their time to getting the coal […]