var c = 1;

var image1 = new Image();
image1.src = "images/cobblestone_n_1.jpg";
var image2 = new Image();
image2.src = "images/cobblestone_n_2.jpg";
function disp_img(w)
	{
	if (c == 3)
		{
		c = 1;
		}
	var img_src = "images/cobblestone_n_" + c + ".jpg";
	document.ani.src = img_src;
	c++;
	}
	
t = setInterval("disp_img(c)", 3000);