if (document.images){

      button1     = new Image ();
      button1.src = "http://www.gerardvossen.nl/website/images/nav_home.gif";

      button2     = new Image ();
      button2.src = "http://www.gerardvossen.nl/website/images/nav_home_on.gif";

      button3     = new Image ();
      button3.src = "http://www.gerardvossen.nl/website/images/nav_cv.gif";

      button4     = new Image ();
      button4.src = "http://www.gerardvossen.nl/website/images/nav_cv_on.gif";

      button5     = new Image ();
      button5.src = "http://www.gerardvossen.nl/website/images/nav_kunst.gif";

      button6     = new Image ();
      button6.src = "http://www.gerardvossen.nl/website/images/nav_kunst_on.gif";

      button7     = new Image ();
      button7.src = "http://www.gerardvossen.nl/website/images/nav_onderwijs.gif";

      button8     = new Image ();
      button8.src = "http://www.gerardvossen.nl/website/images/nav_onderwijs_on.gif";

      button9     = new Image ();
      button9.src = "http://www.gerardvossen.nl/website/images/nav_onderzoek.gif";

      button10     = new Image ();
      button10.src = "http://www.gerardvossen.nl/website/images/nav_onderzoek_on.gif";

      button11    = new Image ();
      button11.src = "http://www.gerardvossen.nl/website/images/nav_huiswerk.gif";

      button12     = new Image ();
      button12.src = "http://www.gerardvossen.nl/website/images/nav_huiswerk_on.gif";

      button13     = new Image ();
      button13.src = "http://www.gerardvossen.nl/website/images/nav_winkel.gif";

      button14     = new Image ();
      button14.src = "http://www.gerardvossen.nl/website/images/nav_winkel_on.gif";

      button15    = new Image ();
      button15.src = "http://www.gerardvossen.nl/website/images/nav_contact.gif";

      button16     = new Image ();
      button16.src = "http://www.gerardvossen.nl/website/images/nav_contact_on.gif";

      }

   // this function swaps the images

function swapImage(oldButton,newButton){
   if (document.images)
      document.images[oldButton].src=eval(newButton + ".src");
}