//editable list of current issue images URLs
arr = new Array(
["/conservation/generic/titles/painting.jpg"],
["/conservation/generic/titles/painting2.jpg"],
["/conservation/generic/titles/painting3.jpg"]
);

//preload these images
preload_image_object = new Image();
var len=arr.length;
var i=0;
for(i=0; i<=len; i++) {preload_image_object.src = arr[i];}

//start on a different image each load
var i =Math.floor(Math.random()*len);

function rotateImg(s) { 
	window.setTimeout('changeImg()', s*1000) 
}

//change span background to next image
function changeImg(){
document.getElementById('randomimg').style.background='url('+ arr[i] +') no-repeat ';
rotateImg(3); //number of seconds to display each one
++i;
if (i==(arr.length)) {i=0;}
}