The Twenty-One Balloons, by William Pene du Bois.
This was one of my favorite childhood books and, upon re-reading it, I find it is just as witty and interesting as I remembered. It tells the story of Professor William Waterman Sherman who, after spending forty years teaching arithmetic at a boys school in San Francisco, is more than ready for some alone time. He designs and builds a house balloon, and sets off across the Pacific Ocean, intending to spend a whole year completely alone and unavailable. Three weeks later, he is picked up in the Atlantic Ocean, clinging to the wreckage of a twenty-balloon platform. How he came to be in the wrong ocean, with too many balloons, wearing a dinner jacket and diamond cuff links, is a story he will only tell in the auditorium of the Western American Explorers' Club, of which he is an honorary member... and in the pages of this book, should you care to read it.