People that Time Forgot, The by Edgar Rice Burroughs (1875 - 1950)

The People that Time Forgot is a science fiction novel, the second of Edgar Rice Burroughs' Caspak trilogy. The first novel ended with the hero writing a manuscript of his adventures and casting it out to sea in his thermos bottle. The second novel begins with the finding of the manuscript and the organization of a rescue expedition. (Adapted from Wikipedia)