The United States Naval Observatory Lantern Slide Collection is a visual representation of the scientific and institutional evolution of the United States Naval Observatory (USNO) and the broader astronomical community during the 19th and 20th centuries. The collection consists primarily of black and white photographic lantern slides, though there is a small grouping of hand-colored slides in the Cataloged and Miscellaneous Lantern Slide Collections. The condition of the slides varies from excellent to shattered. Slides featured within the collection are related to the study and practice of astronomy, astronomers, astronomical clocks and technology, scientific expeditions, and the development of Washington D.C. The collection also includes slides of and from other prominent observatories in the United States and abroad. Subjects include William Herschel, Maria Mitchell, W. H. Steavenson, Reginald L. Waterfield, David Dunlap Observatory, Dominion Astrophysical Observatory, Griffith Observatory, Harvard College Observatory, International Astronomical Union General Assembly, Lick Observatory, Maria Mitchell Association, McDonald Observatory, Mount Wilson Observatory, Radcliffe Observatory, Sterrewacht Leiden, airships, galaxies, planets, solar eclipses, variable stars, reflecting and refracting telescopes, astronomical instruments, women astronomers, Washington DC and Foggy Bottom, and Stonehenge. Creators include R. W. Rhynsburger.