if (document.images) {

 homeon = new Image ();
 homeon.src = "images/smallblankball_on.jpg";
 homeoff = new Image ();
 homeoff.src = "images/smallblankball_off.jpg";

 informationon = new Image ();
 informationon.src = "images/smallblankball_on.jpg";
 informationoff = new Image ();
 informationoff.src = "images/smallblankball_off.jpg";
 
 locationon = new Image ();
 locationon.src = "images/smallblankball_on.jpg";
 locationoff = new Image ();
 locationoff.src = "images/smallblankball_off.jpg"; 
 
 municipalon = new Image ();
 municipalon.src = "images/smallblankball_on.jpg";
 municipaloff = new Image ();
 municipaloff.src = "images/smallblankball_off.jpg"; 

 telemetryon = new Image ();
 telemetryon.src = "images/smallblankball_on.jpg";
 telemetryoff = new Image ();
 telemetryoff.src = "images/smallblankball_off.jpg"; 

 underwateron = new Image ();
 underwateron.src = "images/smallblankball_on.jpg";
 underwateroff = new Image ();
 underwateroff.src = "images/smallblankball_off.jpg"; 
 
 aerialon = new Image ();
 aerialon.src = "images/smallblankball_on.jpg";
 aerialoff = new Image ();
 aerialoff.src = "images/smallblankball_off.jpg";
 
 undergroundon = new Image ();
 undergroundon.src = "images/smallblankball_on.jpg";
 undergroundoff = new Image ();
 undergroundoff.src = "images/smallblankball_off.jpg";
  }
function turnOn(imageName) {
     if (document.images)  {
           document[imageName].src = eval(imageName + "on.src");
         }
     }
function turnOff(imageName) {
     if (document.images) {
           document[imageName].src = eval(imageName + "off.src");
        }
    }