Paul Engel, left, of Yarmouth, inspects a piece of pottery he recovered Wednesday from the site of Fort Richmond in Richmond while volunteering with the Maine Historic Preservation Commission at the dig.  Scientists and volunteers are working around the rain and currently excavating the cobblestone and brick addition to the fort erected on the banks of the Kennebec River between 1740 and 1755, according to archeologist Leith Smith.  The pottery is believed to have come from a chamber pot, Smith said.