function scrollUp(){
  var offy;
  if(self.pageYOffset) {
        offy = self.pageYOffset;
  } else if(document.documentElement && document.documentElement.scrollTop){
        offy = document.documentElement.scrollTop;
  } else {
        offy = document.body.scrollTop;
  }

  if(offy <= 0) return;

  window.scrollBy(0, -50);
  setTimeout("scrollUp()", 10);

}