It leading members were Matthew Boulton, Erasmus Darwin, Thomas Day, Richard Lovell Edgeworth, Samuel Galton, Jr., James Keir, Joseph Priestley, William Small, Jonathan Stokes, James Watt, Josiah Wedgwood, John Whitehurst and William Withering. Other great men of the day visited, or corresponded with, the Society. It had no formal membership list, and was flexible in its arrangements. Anyone could be invited.