var imageFiles_by_15 = new Array();
imageFiles_by_15['0'] = new Array ('_images/by_Melbourne.gif', '_images/by_MelbourneMouseover.gif');

function image_on_by_15 (position) {
   var doc = eval("document.imageby_15" + position);
   doc.src = imageFiles_by_15[position][1];
}

function image_off_by_15 (position) {
   var doc = eval("document.imageby_15" + position);
   doc.src = imageFiles_by_15[position][0];
}