Geology: comparative heights of mountains, with a pyramid for scale. Coloured engraving by S. Hall, 1817. https://www.rawpixel.com/image/13952651/image-cloud-art-skyFree Image from public domain licenseSightseeing at Avalon, Catalina Island, California (1928) by anonymous https://www.rawpixel.com/image/13735683/sightseeing-avalon-catalina-island-california-1928-anonymousFree Image from public domain licensePaarelduikers-spel (1870 - 1899) by anonymous and anonymous https://www.rawpixel.com/image/13780620/paarelduikers-spel-1870-1899-anonymous-and-anonymousFree Image from public domain licenseAn itinerant medicine vendor selling his wares on stage with the aid of an assistant who is extracting a tooth from a man… https://www.rawpixel.com/image/13987834/image-paper-cartoon-personFree Image from public domain license