(function($){
/******************************************************************/
$.fn.columner = function() {
	var speed = 20; // px per second
	var height = this.height();
	var time = height*1000/speed;
	var clone = this.clone().insertAfter(this);
	var item = this.add(clone);
	
	($.fn.columner.move = function() {
		item
			.css('top',0)
			.animate({
				top: -height,
			}, time, 'linear', $.fn.columner.move);
	})();
	
	return this;
}
/******************************************************************/
})(jQuery);