var num=4; // number of slides
if (document.images){

	img = new Array();
	for ( i=1 ; i <= num ; i++ ){
		img[i]=new Image();
		img[i].src="images/"+i+".jpg";
	}
}

 function change(n) {
 	if (document.images){
	next = n ++;
	if (n > num) n = 1;
	document.images['slides'].src=img[n].src;
	setTimeout("change(" + n + ")",3000); // Adjust the speed here 
                                              // 3000 = 3 seconds
     }
}