17. Endeavour to have a move in ambuscade; that is, place the queen, bishop, or rook behind a pawn, or a piece, in such a manner, as that, upon playing that pawn, or piece, you discover a check upon your adversary’s king, and consequently may often get a piece, or some other advantage by it. Suppose the black king on 6, a white bishop on 41, and a pawn on 34; by moving the pawn to 26, a check by the white bishop is discovered upon the black king.
18. Never guard an inferior piece or pawn with a better, if you can do it with a pawn, because that better piece may in such a case be, as it were, out of play.
19. A pawn pushed on, and well supported, often costs the adversary a piece; but one separated from the others is seldom of any value. And whenever you have gained a pawn, or other advantage, and are not in danger of losing the move thereby, make as frequent exchanges as you can.
20. If each player have three pawns upon the board, and no piece, and you have a pawn on one side of the board, and the other two on the other side, and your adversary’s 3 are opposite to your 2, march with your king to take his pawns; and if he move to support them, go on to queen with your single pawn; and if he attempt to hinder it, take his pawns, and push yours to queen; that is, to move a pawn into the adversary’s back row, in order to make a queen, when the original is lost.
21. At the latter end of the game, each party having only three or four pawns on different sides of the board, the kings are to endeavour to gain the move, in order to win the game: for example—the white king placed on 54, and the black king on 37, white would gain the move by playing to 53, or black to 38, and in both cases the adverse king would be prevented from advancing.
22. When the adversary has no more than his king and one pawn on the board, and you a king only, you can never lose that game if you bring and keep your king opposite to your adversary’s, when he is immediately either before or on one side of his pawn, and only one house between the kings. This must then either be a drawn game, or if the opponent persist in his endeavours to win, he will lose by a stale-mate, by drawing you upon the last square.
23. When your adversary has one pawn on the rook’s line, with a king and bishop against a king only, and his bishop is not of the colour that commands the corner-house his pawn is going to, if you can get your king into that corner, you cannot lose that game, but may win by a stale-mate.
24. When you have only your queen left in play, and your king happens to be in that position of stale-mate, keep giving check to your adversary’s king, always taking care not to check him where he can interpose any of his pieces that make the stale: by so doing, you will at last force him to take your queen, and then you win the game by being in stale-mate.
25. Never cover a check with a piece that a pawn pushed upon it may take, for fear of only getting that pawn for it: put a black rook on 7, and a pawn on 40; the white king on 63, and a knight on 61: the white king being on a check to the rook, if the check be covered by moving the white knight to 56, the black pawn could then be moved to 48, and take the knight.
26. Do not crowd your adversary’s king with your pieces, lest you inadvertently give a stale-mate.