Mugdock reservoir

I took this while walking up at Mugdock this morning. It is part of the wall of the reservoir. There is an interesting history to it, I just can't remember what it is!
Hoping for some sun tomorrow and to get out and about in it.

I've just looked up a bit of information and this reservoir was built in 1850 and the photo is of one of the water inlets to Mugdock Reservoir from the Loch Katrine aqueduct.