JQuery Problem: $ not defined (I am trying to implement equal div heights script)

I need a solution that will set the heights of two divs whose class = col to the height of the tallest one.

I found a solution here that I have used to implement this: http://www.cssnewbie.com/example/equal-heights/

This is the code that I have placed on my site:

<script language="javascript" type="text/javascript" href="jquery.js"></script>
<script>
function开发者_Python百科 equalHeight(group) {
    var tallest = 0;
    group.each(function() {
        var thisHeight = $(this).height();
        if(thisHeight > tallest) {
            tallest = thisHeight;
        }
    });
    group.height(tallest);
}
$(document).ready(function() {
    equalHeight($("div.col"));
});
</script>

Unfortunately, this does not solve my problem. When I open the Firefox Error Console, it says me "$ is not defined"

$(".col") should not be the problem right? When I run the command $$(".col") in Firebug Console it returns my two columns just fine.

Please help me with this, as it is driving me crazy! Thank you for your help.

The correct script tag attribute for indicating the location of an external script file is src, not href.

So instead of

<script language="javascript" type="text/javascript" href="jquery.js"></script>

You should use

<script language="javascript" type="text/javascript" src="jquery.js"></script>

Check out this page at W3Schools for more info about the script tag