https://creativecommons.org/publicdomain/zero/1.0/https://www.rawpixel.com/image/13951005Edit ImageSaveSaveEditCropCustom TextNavigation: an astrolabe, a cross-staff, and a back-staff or Davis's sextant. Drawing after Edmund Gunter, 1624.Original public domain image from Wellcome CollectionMorePublic DomainFree CC0 image for Personal and Business useInfoView CC0 LicenseJPEGSmall JPEG 1200 x 720 px | 300 dpiLarge JPEG 2020 x 1212 px | 300 dpiFree DownloadNavigation: an astrolabe, a cross-staff, and a back-staff or Davis's sextant. Drawing after Edmund Gunter, 1624.More