Glasgow Jug

I've been reading more of the Isabel Dalhousie series by Alexander McCall Smith. Probably my favorite thing about them is their setting in Scotland. In one of them, he mentions something called a Glasgow jug. This is what he's referring to. They were made in the late 1800s/early 1900s and were in this shape and often painted in blue and white with this design. I'm not sure what the design signifies, but I think it's nice.