if (document.images) {       //if image object is available     
img1on = new Image();           // MouseOver Images
img1on.src = "images/aboutus-button-on.gif"; 
img2on = new Image();
img2on.src = "images/exhibits-button-on.gif";  
img3on = new Image();
img3on.src = "images/programs-button-on.gif";
img4on = new Image();
img4on.src = "images/support-button-on.gif";
img5on = new Image();
img5on.src = "images/shop-button-on.gif";  
img6on = new Image();
img6on.src = "images/calendar-button-on.gif";
img7on = new Image();
img7on.src = "images/press-button-on.gif";
img8on = new Image();
img8on.src = "images/contactus-button-on.gif";
img9on = new Image();
img9on.src = "images/home-button-on.gif";
imgRentalson = new Image();
imgRentalson.src = "images/rentals-button-on.gif";
imgGalleryon = new Image();
imgGalleryon.src = "images/gallery-button-on.gif";


img1off = new Image();                  // MouseOut Images
img1off.src = "images/aboutus-button-off.gif"; 
img2off = new Image();          
img2off.src = "images/exhibits-button-off.gif";
img3off = new Image();
img3off.src = "images/programs-button-off.gif";
img4off = new Image();
img4off.src = "images/support-button-off.gif";
img5off = new Image();          
img5off.src = "images/shop-button-off.gif";
img6off = new Image();
img6off.src = "images/calendar-button-off.gif";
img7off = new Image();
img7off.src = "images/press-button-off.gif";
img8off = new Image();
img8off.src = "images/contactus-button-off.gif";
img9off = new Image();
img9off.src = "images/home-button-off.gif";
imgRentalsoff = new Image();
imgRentalsoff.src = "images/rentals-button-off.gif";
imgGalleryoff= new Image();
imgGalleryoff.src = "images/gallery-button-off.gif";



function imgOn(imgName) {
        if (document.images) {
            document[imgName].src = eval(imgName + "on.src");        }}
                        
function imgOff(imgName) {
        if (document.images) {
            document[imgName].src = eval(imgName + "off.src");        }}
}