var backgrounds = [
            "/_img/layout/header/546-09.jpg",
            "/_img/layout/header/546-14.jpg",
            "/_img/layout/header/546-21.jpg",
            "/_img/layout/header/1015-01.jpg",
            "/_img/layout/header/1015-04.jpg",
            "/_img/layout/header/1015-11.jpg",
            "/_img/layout/header/1015-12.jpg",
            "/_img/layout/header/1015-14.jpg",
            "/_img/layout/header/1015-17.jpg",
            "/_img/layout/header/1635-36.jpg",
            "/_img/layout/header/1635-39.jpg"
                    ];

var current_index = 0;

$(document).ready(function() {
        window.setInterval("swapBackground()", 7000);
});

function swapBackground() {
    if (current_index < backgrounds.length-1) {
        current_index++;
    } else {
        current_index = 0;
    }
    
    $('#header').css("background-image", "url(" + backgrounds[current_index] + ")");
}