Event.observe(window, 'load', function() {
  var links = $$('ul.galleryImages li a');  
  links.each(function(link) {         
    link.observe('click', function(event) {  
        $("galleryimage").src = link.href;     
	if (event.preventDefault) {
      		event.stopPropagation();
      		event.preventDefault();
    	} else {
      		event.returnValue = false;
      		event.cancelBubble = true;
  	}   
     })               
  });    
});