var num=0;
 
 function swapimage (dir) {
 num=num + dir;
 if (num==-1) { num = 1;}
 if (num ==2) { num = 0; }
    ajaxpage('chatham_gallery.php', 'contentHolder', 'sid='+num, this);
    document.getElementById('imgNum').innerHTML=num+1;
    document.getElementById('enlargeLink').href='img/chatham_gallery/'+num+'pic_enlarge.jpg';
    if (num == 0) {
      document.getElementById('pdfLink').innerHTML='&nbsp;&nbsp;|&nbsp;<a href="pdf/sitemap.pdf" target="_Blank"><img src="img/ico-pdf.gif" alt="PDF" border="0" align="top" /></a>';
      }
     else {
      document.getElementById('pdfLink').innerHTML='&nbsp;&nbsp;|&nbsp;<img src="img/c.gif" alt="" border="0" align="top" />';
      document.getElementById('pdfLink').style.color='#ffffff';
     }
   }