<script id="jquery" type="text/javascript" src="resources/js/jquery-1.8.2.js"></script>
<script id="masonry" type="text/javascript" src="resources/js/masonry-2.1.5.js"></script>

<script>

$(document).ready(function(){
    var $container = $('.x-list-container');
    $container.imagesLoaded(function(){
        $container.masonry({
        itemSelector: '.x-list-item',
        });
    });
});

</script>

<div class="x-list-container">
    <div class="x-list-item"></div> // 'x-list-item' is the block I want to float
    <div class="x-list-item"></div>
    ...
</div>