if (document.images) 
{
   img1 = new Image();
   img2 = new Image();
   img3 = new Image();
   img4 = new Image();
   img5 = new Image();
   img6 = new Image();
   img1.src = "graphics/examples/advertising1.jpg";
   img2.src = "graphics/examples/advertising2.jpg";
   img3.src = "graphics/examples/advertising3.jpg";
   img4.src = "graphics/examples/advertising4.jpg";
   img5.src = "graphics/examples/advertising5.jpg";
   img6.src = "graphics/examples/advertising6.jpg";
}