The ship Maria Pesto was blown over the Rim near the Bay of Mante during a dreadful storm. It briefly orbited the Disc before crashing back down onto the surface near TinLing, on a reef. The ship's only survivor raved "My god, it's full of elephants!" before dying. He also commented that things floated around the air as if they had become extremely light.
Leonard of Quirm designed and built the Kite based on this account (as well as his own observation that the Sun and Moon also tended to orbit the Disc). He also prepared a number of special devices for a weightless environment, such as a pan that sticks to anything and a pen that writes upside down.
The text "My god, it's full of elephants" is the discworld version of the famous exclamation "My god, it's full of stars" from the science fiction movie "2001: A Space Odyssey".