var slideSwitchInterval;
var slideEnabled = true;
function slideSwitch() {
  if( slideEnabled ) {
    var $visible = $('div.slide.visible');
    var $last = $('div.slide:last');

    if( $visible[0] == $last[0] ){
      var $next = $('div.slide:first');
    } else {
      var $next = $visible.next();
    }

    $visible.fadeOut( 'fast', function () {
      $visible.removeClass( 'visible' );
      $next.addClass( 'visible' );
      $next.fadeIn( 'fast' );
    });
  }
}

$( document ).ready( function(){
  slideSwitchInterval = setInterval( 'slideSwitch()', 5000 );
});