How to keep page in same position when .ajax function loads new content

How to keep page in same position when .ajax function loads new content

On my site, I have a rather large header that is on each page of my website. I'm using jQuery and ajax to load in new content below the header, however every time this happens, the page resets its scroll position back to the top, as if I've loaded a completely new page in full.

Is there a way that I can use ajax to get the new content, without the position of the page changing? So basically the user only has to scroll down past the header once - which is mainly for people with smaller screens.

Hopefully that makes sense

Thanks
Denno