function tab1(page) {
mframe.location ="http://www.essexstudent.com/test/tab1/"
}

function tab2(page) {
mframe.location ="http://www.essexstudent.com/test/tab2/"
}

function tab3(page) {
mframe.location ="http://www.essexstudent.com/test/tab3/"
}

function tab4(page) {
mframe.location ="http://www.essexstudent.com/test/tab4/"
}
var rotTol = 5;
var currentDis = 1;

function rotate(page){
if (currentDis == rotTol) {
     tab1(page);
     currentDis = 1;
}
else if (currentDis == 1) {
     tab1(page);
}
else if (currentDis == 2) {
     tab2(page);
}
else if (currentDis == 3) {
     tab3(page);
}
else if (currentDis == 4) {
     tab4(page);
}
currentDis++;

}
window.setInterval("rotate()",4000);