I have a JavaScript file, which also uses jQuery in it too. To load it, I wrote this code:

```
function include(filename)
{
    var head = document.getElementsByTagName('head')[0];
    var script = document.createElement('script');
    script.src = filename;
    script.type = 'text/javascript';
    head.appendChild(script)
}

include('http://ajax.googleapis.com/ajax/libs/jquery/1.7.0/jquery.min.js');
alert("1");

$(document).read(function(){});
alert("2");

```

This fires `alert("1")`, but the second `alert` doesn't work. When I inspect elements, I see an error which says that `$` in not defined.

How should I solve this problem?