jQuery get height of first 3 li tags

I am filling a unordered list with dynamic content and the list height will fir the content, does anyone know how I can get the height of the first 3 li tags in the unordered list?

The dynamic content produced might be something like below so I just want to be able to calculate the height of the first 3 li tags.

<ul>
<li>23 Feb 2011<br />Synergy Launch new website...<br />Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nunc gravida lacus a ligula dictum dignissim....</li>
<li>23 Feb 2011<br />Expat children "receive improv...<br />Expat children enjoy a better standard of education whilst living abroad compared to their home country according to the HSBC Offshore Offspring Report,...</li>
<li>25 Feb 2011<br />London Market favours Landlord...<br />The lettings market has swung dramatically in favour of landlords as an average six applicants chase every available property in London. This is a dramatic rise...</li>
<li>23 Feb 2011<br />Synergy Launch new website...<br />Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nunc gravida lacus a ligula dictum dignissim....</li>
</ul>

Thanks for any help J.