if (document.images) {
port1a = new Image;
port1b = new Image;
port1c = new Image;
port1a.src = 'images/port1_a.jpg';
port1b.src = 'images/port1_b.jpg';
port1c.src = 'images/port1_c.jpg';
} else {
port1a = '';
port1b = '';
port1c = '';
document.rollimg = '';
}