A piece of metal whose heterogeneity is apparent when viewed through x-ray. Photoprint from radiograph by W.K. Röntgen, 1895. https://www.rawpixel.com/image/14005661/image-paper-art-patternFree Image from public domain license[Untitled photo, possibly related to: Gopher hole employing steam power, Williamson County, Illinois (see 26940-D)]. Sourced… https://www.rawpixel.com/image/12315313/image-steam-sky-smokeFree Image from public domain license[Untitled photo, possibly related to: Gopher hole employing steam power, Williamson County, Illinois (see 26940-D)]. Sourced… https://www.rawpixel.com/image/12315251/image-steam-person-skyFree Image from public domain license[Untitled photo, possibly related to: Innoculating a hog for cholera. Irwinville Farms, Georgia]. Sourced from the Library… https://www.rawpixel.com/image/12309464/image-face-hand-personFree Image from public domain licenseGeneral view from top of coal mine tressle, showing burning slag heaps and holes of slate, Maidsville, West Virginia.… https://www.rawpixel.com/image/12242671/photo-image-plant-sky-forestFree Image from public domain license[Untitled photo, possibly related to: General view from top of coal mine tressle, showing burning slag heaps and holes of… https://www.rawpixel.com/image/12242667/photo-image-plant-sky-forestFree Image from public domain license[Untitled photo, possibly related to: Gopher hole employing steam power, Williamson County, Illinois (see 26940-D)]. Sourced… https://www.rawpixel.com/image/12314110/image-cloud-steam-plantFree Image from public domain licenseGopher hole employing steam power, Williamson County, Illinois (see 26940-D). Sourced from the Library of Congress. https://www.rawpixel.com/image/12314116/image-steam-person-skyFree Image from public domain license[Untitled photo, possibly related to: Wheat straw coming out of threshing machine, Frederick, Maryland]. Sourced from the… https://www.rawpixel.com/image/12314228/image-smoke-public-domain-natureFree Image from public domain license[Untitled photo, possibly related to: Railroad yards, Omaha, Nebraska]. Sourced from the Library of Congress. https://www.rawpixel.com/image/12310541/image-moon-sky-smokeFree Image from public domain license[Untitled photo, possibly related to: Structures housing poor whites and blacks, Hamilton County, Ohio]. Sourced from the… https://www.rawpixel.com/image/12307542/image-person-moon-skyFree Image from public domain licenseReverend Eavens, a man with a hole in his chest, seated; with Reverend Kipe, standing. Albumen print by W.C. Bell. https://www.rawpixel.com/image/14008436/photo-image-face-person-smokeFree Image from public domain license[Untitled photo, possibly related to: Gopher hole employing steam power, Williamson County, Illinois (see 26940-D)]. Sourced… https://www.rawpixel.com/image/12315526/image-steam-person-skyFree Image from public domain licenseClosing up hole of grain boat. Superior, Wisconsin. Sourced from the Library of Congress. https://www.rawpixel.com/image/12285038/photo-image-person-smoke-public-domainFree Image from public domain license