Silas Lapham’s long-lasting paint, made with minerals found on his family’s farm in Vermont, has helped make him a millionaire—as has hard work, ambition, and tough business sense. Now that he’s reached late middle age, he’s a success. A newspaper is writing him up in its “Solid Men of Boston” series, his family goes to seaside resorts in the summer, the scion of the aristocratic Covey family has joined his...