I always thought...

..that this was a Pump House on Threipmuir. But today I went inside and this is what I found.

My friend Bill - whose speciality was building reservoirs all over Scotland and all over the world - says from the description that it is most likely a gathering point for springs from the hillside. Originally the plan was that as much of that spring water as possible would be guided past the reservoir and into the water courses below - to maintain our rivers. I never thought of that! Bet Mr Flum - of flumgummery fame - knows about it too!