var interval = 4500;
  var imageNum = 0;
  var captionNum = 0;
  var ImageDir = "";
  var imageArray = new Array();
  var captionArray = new Array();

  function imageItem(image_location)
  { 
    this.image_item = new Image();
    this.image_item.src = image_location;
  }
  function get_ImageItemLocation(imageObj)
  {
    return(imageObj.image_item.src)
  } 
  function getNextImage()
  {
    imageNum = (imageNum+1) % totalImages;
    var new_image = get_ImageItemLocation(imageArray[imageNum]);
    return(new_image);
  } 
  function getPrevImage()
  {
    imageNum = (imageNum-1) % totalImages;
    var new_image = get_ImageItemLocation(imageArray[imageNum]);
    return(new_image);
  } 
  function prevImage(place)
  {
    var new_image = getPrevImage();
    document[place].src = new_image;
    var c = document.getElementById("slideCaption");
    c.innerHTML=captionArray[imageNum];
  } 
  function switchImage(place)
  {
    var new_image = getNextImage();
    document[place].src = new_image;
    var c = document.getElementById("slideCaption");
    c.innerHTML=captionArray[imageNum];
    var recur_call = "switchImage('"+place+"')";
    timerID = setTimeout(recur_call, interval);
  }