To reveal even more information, architectural historian Mark Wenger carefully chipped away the ca. 1882 finish coat that overlaid the ca. 1812 plaster.  When he was finished he found an almost exact outline of the chimney cap's profile preserved in paint under the later plaster.  As it turns out, when President Madison’s painters were painting the chimney cap, they absentmindedly brushed paint onto the plaster, accidently producing an almost perfect outline of the cap’s profile on the ca 1812 plaster.  To reconstruct the cap, Wenger traced the profile onto a piece of clear plastic and used the tracing, along with historic examples of chimney caps, to produce a design for the reconstructed cap.