This image was acquired from
flickr. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
stereographs centennial exhibition centennialexhibition philadelphia library company of philadelphia librarycompanyofphiladelphia second industrial revolution secondindustrialrevolution henry pettit henrypettit joseph wilson josephwilson steam power steampower hydraulic power hydraulicpower photo border Philadelphia Centennial Photographic