if (document.images) {
                var queenOff = new Image(130, 100);
                queenOff.src = "images/queen1.jpg";
                var queenOn = new Image(130, 100);
                queenOn.src = "images/queen2.jpg";}

        function turnOn (imgName) {
                if (document.images)
                        document [imgName].src = eval (imgName + "On.src");}
        function turnOff (imgName) {
                if (document.images)
                        document [imgName].src = eval (imgName + "Off.src");}