var gal_img_num = 1;
$(document).ready(function(){
	$('.gallery_tb').click(function(){
		var num = this.id.substr(3);
		$('.gallery_main').hide();
		$('#main_'+num).fadeIn('def');
		gal_img_num = num;
	});
});

$(document).everyTime(5000, function() {
  if(gal_img_num>3)gal_img_num=0;
  n = gal_img_num;
  $('.gallery_main').hide();
  $('#main_'+n).fadeIn('slow');
  gal_img_num++;
});