var old = 0;
function changeImage () {
  do {
    num = Math.ceil(Math.random()*12);
  }
  while (old == num);
  old = num;
  var url = 'http://rochesterwellfest.com/img/'+num+'.jpg';
  var newImage = new Image();
  newImage.onload = (function() {
    $('rotate').setProperty('src',url);
    changeImage.delay(5000,this);
  }).bind(this);
  newImage.src = url;
}

Window.onDomReady(function() {
    changeImage();
  });