function animation1(){
    document.images['vulkan'].src='pics/v_ani_1.jpg';
    setTimeout('animation2()',1200);
}
function animation2(){
    document.images['vulkan'].src='pics/v_ani_2.jpg';
    setTimeout('animation3()',1200);
}
function animation3(){
    document.images['vulkan'].src='pics/v_ani_3.jpg';
    setTimeout('animation1()',1200);
}