var current = 0;
var myPics = new Array();

function addPic(_p) {
  myPics[myPics.length?myPics.length:0] = new Image();
  myPics[myPics.length-1].src=_p; // preload all pics
}

addPic("images/Slideshow/1.jpg");
addPic("images/Slideshow/2.jpg");
addPic("images/Slideshow/3.jpg");
addPic("images/Slideshow/4.jpg");
addPic("images/Slideshow/5.jpg");
addPic("images/Slideshow/6.jpg");
addPic("images/Slideshow/7.jpg");
addPic("images/Slideshow/8.jpg");
addPic("images/Slideshow/9.jpg");
addPic("images/Slideshow/10.jpg");
addPic("images/Slideshow/11.jpg");
addPic("images/Slideshow/12.jpg");
addPic("images/Slideshow/13.jpg");
addPic("images/Slideshow/14.jpg");
addPic("images/Slideshow/15.jpg");
addPic("images/Slideshow/16.jpg");
addPic("images/Slideshow/17.jpg");
addPic("images/Slideshow/18.jpg");
addPic("images/Slideshow/19.jpg");
addPic("images/Slideshow/20.jpg");

function checkIt(val) {
  current = Math.abs((current+parseInt(val))%myPics.length);
  document.myimg.src = myPics[current].src;
}

document.write("<img name=myimg alt='' src='"+myPics[current].src+"' width='300' height='300'>");
var myTimer = setInterval('checkIt(1)',6000); // 3 second interval;