How to modify this function

Hi guys. I use the following function to make a few mc’s visible on the stage with a setInterval.

function showClips() {
if (clips.length) {
clips[0]._visible = true;
clips.splice(0, 1);
} else {
var clips = [];
var index = 0;
while (index++<15) {
var clip = eval("thump_"+(index<10 ? "0" : "")+index);
clip._visible = false;
var id = setInterval(showClips, 1000);

This way the clips appear with a intervalof one second untill all are visible.
Attached is the zip. What i want is that they appear using a fade function instead of _visible. and that the entire process start all over again when all are faded in!

Anybody an idea?

Thanks in advance