var ImgNum = 0;
      var ImgLength = NewImg.length -1;

      function chgImg(direction) {
        if (document.images) {
	  ImgNum = ImgNum + direction;
	  if (ImgNum > ImgLength) {
	    ImgNum = 0;
	  }
	  if (ImgNum < 0) {
	    ImgNum = ImgLength;
	  }
	  document.slideshow.src = NewImg[ImgNum];
	}
      }