Watt & Wedgwood

Science Museum | London (Community-in-Residence)
Phil (Rowley) sent this interesting message - He writes:
I took a look at one of the photo sets on this blog and, while looking at the photos, I came across one which really intrigued me - ceramic trials made by James Watt as a reposte to those which Josiah Wedgwood was making.
I've checked and, as far as I can see, there was never any pottery manufacturing in the Watt family, so why was he making trial pieces? It raises interesting questions about Wedgwood, Watt and the Lunar Society! I'm hoping to be able to learn more about the details during the weekend
Any ideas or further information?