var scrolling = null; 
   
function scroll_up()
{ 
	var d = document.getElementById('scroll'); 
   
	d.scrollTop = d.scrollTop - 1; 
   
	scrolling = window.setTimeout(function() { 
		scroll_up(); 
	}, 10); 
} 
   
function scroll_down()
{ 
	var d = document.getElementById('scroll'); 

	d.scrollTop = d.scrollTop + 1; 

	scrolling = window.setTimeout(function() { 
		scroll_down(); 
	}, 10);
} 
   
function stop_scroll()
{ 
	window.clearTimeout(scrolling); 
}