function switchMenu(obj) {
document.getElementById("census").style.display = "none";
document.getElementById("history").style.display = "none";
document.getElementById("theories").style.display = "none";
document.getElementById("facts").style.display = "none";
document.getElementById("trees").style.display = "none";
document.getElementById("art").style.display = "none";

  var el = document.getElementById(obj);
  if ( el.style.display != 'none' ) {
    el.style.display = 'none';
  }
  else {
    el.style.display = '';
  }
}

function lite(obj) { 
 if(document.all&&!window.opera) { 
  obj.filters.blendTrans.apply(); 
  obj.filters.blendTrans.play(); 
 } 
}