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

var delay = 4000; // time btwn slides (ms)
var lock = true;
var run = setInterval("chgImg(1)", delay);

function chgImg() {
if (document.images) {
	ImgNum = ImgNum + 1;
	if (ImgNum > ImgLength) { ImgNum = 0; }
	if (ImgNum < 0) { ImgNum = ImgLength; }
	document.slideshow.src = "images/" + SlideImages[ImgNum];
	document.getElementById('slideCaption').innerHTML = SlideNames[ImgNum];
	}
}

function auto() {
if (lock == true) {
	lock = false;
	window.clearInterval(run);
} else if (lock == false) {
	lock = true;
	run = setInterval("chgImg(1)", delay);
	}
}