Animation In JavaScript

<html>

<head>
    <script type="text/javascript">
        function mouseOver() {
            document.b1.src = "Sunset.jpg";
        }

        function mouseOut() {
            document.b1.src = "Water lilies.jpg";
        }
    </script>
</head>

<body>
    <a href="http://www.shctpt.edu
target=" _blank ">
<img border="0 "
alt="To Visit Sacred Heart College Web Site "
src="Water lilies.jpg "
name="b1 "
width="500 "
height="500 "
onmouseOver="mouseOver() "
onmouseOut="mouseOut() " />
</a>
</body>
</html>