Photo from the Huntington Digital Library (undated). There are 7 photos showing 96 different insulators tested. Southern California Edison Collection of Photographs, Courtesy of the Huntington Library, San Marino, California. For future reference, the first photo in this series can be found here: http://hdl.huntington.org/cdm/singleitem/collection/p16003coll2/id/28961/rec/11