These pictures were taken with Grandpa's glass negative camera and are in fact a form of "double exposure" where half the lens was covered in some manner, then exposure made. Then the subject with appropriate objects were moved and the other half exposed. My dad, Walter, must have been Grandpa's guinea pig! You can see the division clearly on the first one. Then practice made perfect on the latter ones.

Photo Album of Arliss Baumgarten Powell