https://creativecommons.org/publicdomain/zero/1.0/https://www.rawpixel.com/image/13970673Edit ImageSaveSaveEditCropCustom TextThree balloons travel over a polar landscape: proposed method of reaching the North Pole by J.P. Cheyne. Coloured wood engraving by C. Roberts, 1877.Original public domain image from Wellcome CollectionMorePublic DomainFree CC0 image for Personal and Business useInfoView CC0 LicenseJPEGSmall JPEG 1200 x 791 px | 300 dpiLarge JPEG 3424 x 2257 px | 300 dpiFree DownloadThree balloons travel over a polar landscape: proposed method of reaching the North Pole by J.P. Cheyne. Coloured wood engraving by C. Roberts, 1877.More