var how_many_postcards = 14;
var now = new Date()
var sec = now.getSeconds()
var pc = sec % how_many_postcards;
pc +=1;

if (pc==1) {

postcard="images/t-picture-01.jpg";
width="140";
height="93";
}
if (pc==2) {

postcard="images/t-picture-02.jpg";
width="140";
height="93";
}
if (pc==3) {

postcard="images/t-picture-03.jpg";
width="140";
height="93";
}
if (pc==4) {

postcard="images/t-picture-04.jpg";
width="140";
height="93";
}
if (pc==5) {

postcard="images/t-picture-05.jpg";
width="140";
height="93";
}
if (pc==6) {

postcard="images/t-picture-06.jpg";
width="140";
height="93";
}
if (pc==7) {

postcard="images/t-picture-07.jpg";
width="140";
height="93";
}
if (pc==8) {

postcard="images/t-picture-08.jpg";
width="140";
height="93";
}
if (pc==9) {

postcard="images/t-picture-09.jpg";
width="140";
height="93";
}
if (pc==10) {

postcard="images/t-picture-10.jpg";
width="140";
height="93";
}
if (pc==11) {

postcard="images/t-picture-11.jpg";
width="140";
height="93";
}
if (pc==12) {

postcard="images/t-picture-12.jpg";
width="140";
height="93";
}
if (pc==13) {

postcard="images/t-picture-13.jpg";
width="140";
height="93";
}

if (pc==14) {

postcard="images/t-picture-14.jpg";
width="140";
height="93";
}

document.write('<img src=\"' + postcard + '\" width=')
document.write(width + ' height=' + height + ' ');