awaken in a changed society, or are transported to the past through supernatural means. Among them L'An 2440, rêve s'il en fût jamais (The Year 2440: A Dream If Ever There Was One, 1770) by Louis-Sébastien Mercier, Rip Van Winkle (1819) by Washington Irving, Looking Backward (1888) by Edward Bellamy, and When the Sleeper Awakes (1899) by H.G. Wells. Prolonged sleep, like the later more familiar time machine, is used as a means of time travel in these stories. The earliest work about backwards time travel is uncertain. The Chinese novel Supplement to the Journey to the West (c. 1640) by Dong Yue features magical mirrors and jade gateways that connect various points in time. The protagonist Sun Wukong travels back in time to the "World of the Ancients" (Qin Dynasty) to retrieve a magical bell and then travels forward to the "World of the Future" (Song Dynasty) to find an emperor who has been exiled in time. However, the time travel takes place inside an illusory dream world created by the villain to entrap and distract him. Samuel Madden's Memoirs of the Twentieth Century (1733) is a series of letters from British ambassadors in 1997 and 1998 to diplomats in the past, conveying the political and religious conditions of the future. Because the narrator receives these letters from his guardian angel, Paul Alkon suggests in his book Origins of Futuristic Fiction that "the first time-traveler in English literature is a guardian angel". Madden does not explain how the angel obtains these documents, but Alkon asserts that Madden "deserves recognition as the first to toy with the rich idea of time-travel in the form of an artifact sent backward from the future to be discovered in the present". In the science fiction anthology Far Boundaries (1951), editor August Derleth claims that an early short story about time travel is An Anachronism; or, Missing One's Coach, written for the Dublin Literary Magazine by an anonymous author in the June 1838 issue. While the narrator waits under a tree for a coach to take him out of Newcastle upon Tyne, he is transported back in time over a thousand years. He encounters the Venerable Bede in a monastery and explains to him the developments of the coming centuries. However, the story never makes it clear whether these events are real or a dream. Another early work about time travel is The Forebears