var dimages=new Array();
var numImages=15;
for (i=0; i<numImages; i++)
{
dimages[i]=new Image();
dimages[i].src="/photos/dna_testing_"+(i+1)+".jpg";
}
var curImage=-1;
function swapPicture()
{
if (document.images)
{
var nextImage=curImage+1;
if (nextImage>=numImages)
nextImage=0;
if (dimages[nextImage] && dimages[nextImage].complete)
{
var target=0;
if (document.images.headers)
target=document.images.headers;
if (document.all && document.getElementById("headers"))
target=document.getElementById("headers");
// make sure target is valid.  It might not be valid
//   if the page has not finished loading
if (target)
{
target.src=dimages[nextImage].src;
curImage=nextImage;
}
setTimeout("swapPicture()", 4000);
}
else
{
setTimeout("swapPicture()", 500);
}
}
}
setTimeout("swapPicture()", 4000);