var cantin=document.getElementById("cantin");

  var con1=document.getElementById("con1");

  var con2=document.getElementById("con2");

cantin.scrollTop = 0;

 con2.innerHTML=con2.innerHTML;

function scrollUp(){

var   h=cantin.scrollTop ++;

 return  h;

   }

alert(scrollUp);

var timer=setInterval("scrollUp",50);