> Imagine : on a website you offer emages via a refreshing 
> cam. The image (webcam.gif or webcam.jpg) is in a 
dedicated 
> html page (webcam.html) with nothing else.
> Is it possible for me to captures this images 
automatically 
> ie to get all images on a 30 or 60sec rate. but not to 
> erase the former images.

No ; not without some unix-like scripting
while true; do