$(document).ready(function() {
  setInterval(slideShow, 10000);
})

slideShow = function() {
  var $active = $(".slideshow .active")
  
  if ( $active.length == 0 ) $active = $(".slideshow div:last");
  
  var $next = $active.next().length ? $active.next() : $(".slideshow div:first");
  
  $active.addClass('last-active');
  
  $next.css({opacity: 0.0})
    .addClass('active')
    .animate({opacity: 1.0}, 5000, function(){
      $active.removeClass('active last-active');
    });
}