Edmond Hamilton 
Captain Future #8: The Lost World of Time [EPUB ebook] 

The Futuremen race into the past to answer a cry for help that has traveled across a hundred million years! Follow Captain Future as the greatest enigma of all time transports him into the forgotten ages.
The Captain Future saga follows the super-science pulp hero Curt Newton, along with his companions, The Futuremen: Grag the giant robot, Otho the android, and Simon Wright the living brain in a box. Together, they travel the solar system in series of classic pulp adventures, many of which written by the author of The Legion of Super-Heroes, Edmond Hamilton.