Add class to wordpress image gallery

HTML

<div id="gallery-1" class="galy">
  <dl class="gallery-item">
    <dt class="gallery-icon">
      <a href="#">
        <img width="75" height="75" src="http://dummyimage.com/75x75/000/fff.jpg" class="attachment-thumbnail" />
      </a>
    </dt>
  </dl>

  <dl class="gallery-item">
    <dt class="gallery-icon">
      <a href="#">
        <img width="75" height="75" src="http://dummyimage.com/75x75/000/fff.jpg" class="attachment-thumbnail" />
      </a>
    </dt>
  </dl>

  <dl class="gallery-item">
    <dt class="gallery-icon">
      <a href="#">
        <img width="5" height="75" src="http://dummyimage.com/75x75/000/fff.jpg" class="attachment-thumbnail" />
      </a>
    </dt>
  </dl>

  <dl class="gallery-item">
    <dt class="gallery-icon">
      <a href="#">
        <img width="75" height="75" src="http://dummyimage.com/75x75/000/fff.jpg" class="attachment-thumbnail" />
      </a>
    </dt>
  </dl>
</div>

CSS

#gallery-1 {
  margin: auto;
}
#gallery-1 .gallery-item {
  float: left;
  margin-top: 10px;
  text-align: center;
  width: 25%;            }
#gallery-1 img {
  border: 5px solid #cfcfcf;
}
#gallery-1 .gallery-caption {
  margin-left: 0;
}

JavaScript

$(document).ready(function(){
  $('div.gall').each(function(i) {
    $('.attachment-thil').parent().addClass('view');
  });
});