if (document.images) {            
            img1on  = new Image();   img1on.src  = "images/about_b1a.gif"; 
            img2on  = new Image();   img2on.src  = "images/about_b2a.gif";
            img3on  = new Image();   img3on.src  = "images/about_b3a.gif";  
            img4on  = new Image();   img4on.src  = "images/about_b4a.gif";  
            img5on  = new Image();   img5on.src  = "images/about_b5a.gif";
            img6on  = new Image();   img6on.src  = "images/about_b6a.gif";
            img7on  = new Image();   img7on.src  = "images/about_b7a.gif";
            img8on  = new Image();   img8on.src  = "images/about_b8a.gif";
            img9on  = new Image();   img9on.src  = "images/about_b9a.gif";
            img10on = new Image();   img10on.src = "images/about_b10a.gif";
            img11on = new Image();   img11on.src = "images/about_b11a.gif";
            img12on = new Image();   img12on.src = "images/about_b12a.gif";
            img13on = new Image();   img13on.src = "images/about_b13a.gif";
			img14on = new Image();   img14on.src = "images/about_b14a.gif";
			img15on = new Image();   img15on.src = "images/about_b15a.gif";
            

            img1off  = new Image();  img1off.src  = "images/about_b1.gif";
            img2off  = new Image();  img2off.src  = "images/about_b2.gif";
            img3off  = new Image();  img3off.src  = "images/about_b3.gif";
            img4off  = new Image();  img4off.src  = "images/about_b4.gif";
            img5off  = new Image();  img5off.src  = "images/about_b5.gif";
            img6off  = new Image();  img6off.src  = "images/about_b6.gif";
            img7off  = new Image();  img7off.src  = "images/about_b7.gif";
            img8off  = new Image();  img8off.src  = "images/about_b8.gif";
            img9off  = new Image();  img9off.src  = "images/about_b9.gif";
            img10off = new Image();  img10off.src = "images/about_b10.gif";
            img11off = new Image();  img11off.src = "images/about_b11.gif";
            img12off = new Image();  img12off.src = "images/about_b12.gif";
            img13off = new Image();  img13off.src = "images/about_b13.gif";
			img14off = new Image();  img14off.src = "images/about_b14.gif";
			img15off = new Image();  img15off.src = "images/about_b15.gif";
      }

    function imgOn(imgName) {
            if (document.images) {
                document[imgName].src = eval(imgName + "on.src");       
            }
    }

    function imgOff(imgName) {
            if (document.images) {
                document[imgName].src = eval(imgName + "off.src");        
            }
    }