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.

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.

The Queen is usually reckoned equal, in average situations, to two Rooks and a Pawn, but towards the end of a game she is hardly so valuable as two Rooks.

Be cautious of playing your Queen in front of your King and in subjecting yourself to a discovered check. It is better when check is given to your King to interpose a man that attacks the checking Piece than with one that does not.

For touching an adversary's man, when it cannot be captured, the offender must move his King.

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.

The Bishop and Knight, in contradistinction to the Queen and Rook, are called Minor Pieces.