if (document.images) {
	
	img1on = new Image();           // The onmouseover image
	img1on.src = "images/10.gif";  
	img2on = new Image();
	img2on.src = "images/20.gif";  
	img3on = new Image();
	img3on.src = "images/30.gif";
	img4on = new Image();
	img4on.src = "images/40.gif";
	img1off = new Image();          // The normally seen image
	img1off.src = "images/1.gif"; 
	img2off = new Image();
	img2off.src = "images/2.gif"; 
	img3off = new Image();
	img3off.src = "images/3.gif";
	img4off = new Image();
	img4off.src = "images/4.gif";
	
  }				  //This function changes the image when over.
    function imgOn(imgName) {
            if (document.images) {
            document[imgName].src = eval(imgName + "on.src");
            }
    }				   //This function changes the image back when off.
    function imgOff(imgName) {
            if (document.images) {
            document[imgName].src = eval(imgName + "off.src");        
            }
    }