var delay=2500 //tempo di aggiornamento
		var curindex=0

		var randomimages=new Array()

		randomimages[0]="FotoSierra/sierra1.jpg"
		randomimages[1]="FotoSierra/sierra2.jpg"
		randomimages[2]="FotoSierra/sierra3.jpg"
		randomimages[3]="FotoSierra/sierra4.jpg"
		randomimages[4]="FotoSierra/lab1.jpg"
		randomimages[5]="FotoSierra/lab2.jpg"

		var preload=new Array()

		for (n=0;n<randomimages.length;n++)
		{
			preload[n]=new Image()
			preload[n].src=randomimages[n]
		}

		document.write('<div><img align="right" vspace="5" hspace = "5" name="defaultimage" src="'+randomimages[Math.floor(Math.random()*(randomimages.length))]+'" width="234" height="132"></div>')   // 254 e 132 
    

		function rotateimage()
		{

		if (curindex==(tempindex=Math.floor(Math.random()*(randomimages.length)))){
		curindex=curindex==0? 1 : curindex-1
		}
		else 
		curindex=tempindex

		document.images.defaultimage.src=randomimages[curindex]
		}

		setInterval("rotateimage()",delay)