Travelers planning a trip on a map https://www.rawpixel.com/image/14915482/travellers-planning-trip-mapView licenseCloseup of hands holding color swatch https://www.rawpixel.com/image/14914400/closeup-hands-holding-color-swatchView licenseDirections of Balloons (Addison system), design by Annibal Ardisson (?-1886), a proposal of a system to navigate the… https://www.rawpixel.com/image/429643/free-illustration-image-balloon-vintage-scienceFree Image from public domain licenseAuguste Lanteigne proposes a system of airship navigation utilizing a series of 16 balloons on a single keel. Original from… https://www.rawpixel.com/image/429694/free-illustration-image-vintage-balloon-instructions-airFree Image from public domain license