Beyond the wall we find a spring!

Here's a film of something I've found just outside the West side of the garden.  

As you can see, the stone circle in the garden looks very much like a well.  I wonder if this combined with the spring source I've found were used to irrigate the garden?

P.s If you think I sound a bit stupid on this film, go out and film yourself doing something, whilst narrating what you're doing, it was so awful I didn't want to do a re-run!  Thinking and talking out loud doesn't come naturally to me.