Uncaught ReferenceError: $ is not defined

Uncaught ReferenceError: $ is not defined

I want to use 2 Jquery for my website but i have got this error so can you suggest me what i will do.
My code is :

<!doctype html>
<html lang="en">
    <head>
        <title>Dynamic Shadow</title>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
        <link type="text/css" rel="stylesheet" href="css/style.css" media="all" />
        <link type="text/css" rel="stylesheet" href="css/style1.css" media="all" />


   <script type="text/javascript" src="js/script.js"></script>
         
          
    </head>
    <body>
       
        <div id="switch"></div>
    <div id="light-bulb" class="off"><div id="light-bulb2"></div></div>
        <div id="logo"></div>
        <div id="logosh"></div>
      <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
        <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.7.2/jquery-ui.min.js"></script>        
<script type="text/javascript" src="js/script2.js"></script>
        <div id="logo1"></div></div>
        <div id="logosh1"></div>
       
    
       
        
    </body>

         
</html>