If, during the course of the ...

If, during the course of the game, it be discovered that any error or illegality has been committed in the moves of the pieces, the moves must be retraced, and the necessary correction made, without penalty.
 Howard Staunton

Quotes from the same author

If either player abandon the game by quitting the table in anger, or in an otherwise offensive manner; or by momentarily resigning the game; or refuses to abide by the decision of the Umpire, the game must be scored against him.
 Howard Staunton
To play with correctness and skill the ends of games, is an important but a very rare accomplishment, expect among the magnates of the game.
 Howard Staunton
For playing a man to a square to which it cannot be legally moved, the adversary, at his option, may require him to move the man legally, or to move the King.
 Howard Staunton
In Castling, the King must be moved first, or before the Rook is quitted. If the Rook be quitted before the King is touched, the opposing player may demand that the move of the Rook shall stand without the Castling being completed.
 Howard Staunton
For touching an adversary's man, when it cannot be captured, the offender must move his King.
 Howard Staunton