NewImg = new Array (
"1.jpg",
"2.jpg",
"3.jpg",
"4.jpg",
"5.jpg",
"6.jpg",
"7.jpg",
"8.jpg",
"9.jpg",
"10.jpg",
"11.jpg",
"12.jpg",
"13.jpg",
"14.jpg",
"15.jpg",
"16.jpg",
"17.jpg",
"18.jpg",
"19.jpg",
"20.jpg",
"21.jpg",
"22.jpg",
"23.jpg",
"24.jpg",
"25.jpg",
"26.jpg",
"27.jpg",
"28.jpg",
"29.jpg",
"30.jpg"
);
var ImgNum = 0;
var ImgLength = NewImg.length - 1;

//Time delay between Slides in milliseconds
var delay = 4000;

var lock = false;
var run;
function chgImg(direction) {
if (document.images) {
ImgNum = ImgNum + direction;
if (ImgNum > ImgLength) {
ImgNum = 0;
}
if (ImgNum < 0) {
ImgNum = ImgLength;
}
document.slideshow.src = 'images/' + NewImg[ImgNum];
   }
}
function auto() {
if (lock == true) {
lock = false;
window.clearInterval(run);
}
else if (lock == false) {
lock = true;
run = setInterval("chgImg(1)", delay);
   }
}

<!-- Original:  Mike Canonigo (mike@canonigo.com) -->
<!-- Web Site:  http://www.munkeehead.com -->

<!-- This script and many more are available free online at -->
<!-- The JavaScript Source!! http://javascript.internet.com -->