if (document.images) {
            img0on=new Image();
            img0on.src="art/lay.jpg";       // Active Images
            img1on=new Image();
            img1on.src="art/ray.jpg";       
            img2on=new Image();
            img2on.src="art/lay.jpg";       // Active Images
            img3on=new Image();
            img3on.src="art/ray.jpg";       
            
            
            img0off=new Image();
            img0off.src="art/law.jpg";     // Inactive Images            
            img1off=new Image();
            img1off.src="art/raw.jpg";     
            img2off=new Image();
            img2off.src="art/law.jpg";     // Inactive Images            
            img3off=new Image();
            img3off.src="art/raw.jpg";     


       }


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

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