nav_1_off     = new Image();
nav_1_off.src = 'images/nav_1_off.gif';

nav_1_on     = new Image();
nav_1_on.src = 'images/nav_1_on.gif';

nav_2_off     = new Image();
nav_2_off.src = 'images/nav_2_off.gif';

nav_2_on     = new Image();
nav_2_on.src = 'images/nav_2_on.gif';

nav_3_off     = new Image();
nav_3_off.src = 'images/nav_3_off.gif';

nav_3_on     = new Image();
nav_3_on.src = 'images/nav_3_on.gif';

nav_4_off     = new Image();
nav_4_off.src = 'images/nav_4_off.gif';

nav_4_on     = new Image();
nav_4_on.src = 'images/nav_4_on.gif';

nav_5_off     = new Image();
nav_5_off.src = 'images/nav_5_off.gif';

nav_5_on     = new Image();
nav_5_on.src = 'images/nav_5_on.gif';

nav_6_off     = new Image();
nav_6_off.src = 'images/nav_6_off.gif';

nav_6_on     = new Image();
nav_6_on.src = 'images/nav_6_on.gif';