“Check by discovery” is given when a player, by moving one of his pieces, checks with another of them. “Double check” means attacking the king at once with two pieces—one of the pieces in this case giving check by discovery.
“Perpetual check” occurs when one player, seeing that he cannot win the game, finds the men so placed that he can give check ad infinitum, while his adversary cannot possibly avoid it. The game is then drawn. A game is also drawn “if, before touching a man, the player whose turn it is to play, claims that the game be treated as drawn, and proves that the existing position existed, in the game and at the commencement of his turn of play, twice at least before the present turn.”
“Stalemate.” When a king is not in check, but his owner has no move left save such as would place the king in check, it is “stalemate,” and the game is drawn.
“Castling.” This is a special move permitted to the king once only in the game. It is performed in combination with either rook, the king being moved two squares laterally, while the rook towards which he is moved (which must not have previously moved from its square) is placed next him on the other side; the king must be touched first. The king cannot castle after having been once moved, nor when any piece stands between him and the rook, nor if he is in check, nor when he has to cross a square commanded by an adverse piece or pawn, nor into check. It will be perceived that after castling with the king’s rook the latter will occupy the KB square, while the king stands on the KKt square, and if with the queen’s rook, the latter will occupy the queen’s square while the king stands on the QB square.
“Taking en passant.” This is a privilege possessed by any of the pawns under the following circumstances:—If a pawn, say of the white colour, stands upon a fifth square, say upon K5 counting from the white side, and a black pawn moves from Q2 or KB2 to Q4 or KB4 counting from the black side, the white pawn can take the black pawn en passant. For the purposes of such capture the latter is dealt with as though he had only moved to Q3 or KB3, and the white pawn taking him diagonally then occupies the square the captured pawn would have reached had he moved but one square. The capture can be made only on the move immediately succeeding that of the pawn to be captured.
“Drawn Game.” This arises from a stalemate (noticed above), or from either player not having sufficient force wherewith to effect checkmate, as when there are only two kings left on the board, or king and bishop against king, or king with one knight, or two knights against king, or from perpetual check. One of the players can call upon the other to give checkmate in fifty moves, the result of failure being that the game is drawn. But, if a pawn is moved, or a piece is captured, the counting must begin again.
A “minor piece” means either a knight or a bishop. “Winning the exchange” signifies capturing a rook in exchange for a minor piece. A “passed pawn” is one that has no adverse pawn either in front or on either of the adjoining files. A “file” is simply a line of squares extending vertically from one end of the board to the other. An “open file” is one on which no piece or pawn of either colour is standing. A pawn or piece is en prise when one of the enemy’s men can capture it. “Gambit” is a word derived from the Ital. gambetto, a tripping up of the heels; it is a term used to signify an opening in which a pawn or piece is sacrificed at the opening of a game to obtain an attack. An “opening,” or début, is a certain set method of commencing the game. When a player can only make one legal move, that move is called a “forced move.”
Value of the Pieces.—The relative worth of the chess-men cannot be definitely stated on account of the increase or decrease of their powers according to the position of the game and the pieces, but taking the pawn as the unit the following will be an estimate near enough for practical purposes:—pawn 1, bishop 3.25, knight 3.25, rook 5, queen 9.50. Three minor pieces may more often than not be advantageously exchanged for the queen. The knight is generally stronger than the bishop in the end game, but two bishops are usually stronger than two knights, more especially in open positions.
Laws.—The laws of chess differ, although not very materially, in different countries. Various steps have been taken, but as yet without success, to secure the adoption of a universal code. In competitions among English players the particular laws to be observed are specially agreed upon,—the regulations most generally adopted being those laid down at length in Staunton’s Chess Praxis, or the modification of the Praxis laws issued in the name of the British Chess Association in 1862.
First Move and Odds.—To decide who moves first, one player conceals a white pawn in one hand and a black pawn in the other, his adversary not seeing in which hand the different pawns are put. The other holds out his hands with the pawns concealed, and his adversary touches one. If that contains the white pawn, he takes the white men and moves first. If he draws the black pawn his adversary has the first move, since white, by convention, always plays first. Subsequently the first move is taken alternately. If one player, by way of odds, “gives” his adversary a pawn or piece, that piece is removed before play begins. If the odds are “pawn and move,” or “pawn and two,” a black pawn, namely, the king’s bishop’s pawn, is removed and white plays one move, or any two moves in succession. “Pawn and two” is generally considered to be slightly less in point of odds than to give a knight or a bishop; to give a knight and a bishop is to give rather more than a rook; a rook and bishop less than a queen; two rooks rather more than a queen. The odds of “the marked pawn” can only be given to a much weaker player. A pawn, generally KB’s pawn, is marked with a cap of paper. If the pawn is captured its owner loses the game; he can also lose by being checkmated in the usual way, but he cannot give mate to his adversary with any man except the marked pawn, which may not be moved to an eighth square and exchanged for a piece.