var mess = new Array('<img class="mainimage" src="http://www.dartmouth.edu/apply/images/home/title1.jpg" alt="Welcome to Dartmouth College" width="640" height="340" />','<img class="mainimage" src="http://www.dartmouth.edu/apply/images/home/title2.jpg" alt="Welcome to Dartmouth College" width="640" height="340" />','<img class="mainimage" src="http://www.dartmouth.edu/apply/images/home/title3.jpg" alt="Welcome to Dartmouth College" width="640" height="340" />','<img class="mainimage" src="http://www.dartmouth.edu/apply/images/home/title4.jpg" alt="Welcome to Dartmouth College" width="640" height="340" />','<img class="mainimage" src="http://www.dartmouth.edu/apply/images/home/title5.jpg" alt="Welcome to Dartmouth College" width="640" height="340" />','<img class="mainimage" src="http://www.dartmouth.edu/apply/images/home/title6.jpg" alt="Welcome to Dartmouth College" width="640" height="340" />','<img class="mainimage" src="http://www.dartmouth.edu/apply/images/home/title7.jpg" alt="Welcome to Dartmouth College" width="640" height="340" />');
var max = mess.length;
var num = Math.floor((Math.random() * max));
document.writeln(mess[num]);