In 1911, leading a Yale-sponsored expedition in the Andes, Hiram Bingham discovered the ancient Inca City which he named Machu Picchu and which he believed to be the lost Vilcapampa, secret capital of the last Inca state. Gemming tells of Bingham's discovery and his several Andean expeditions in a fictionalized account which works historical background into stilted conversations. ("" 'Because the Incas were reluctant to destroy their bridges, the Spaniards were able to penetrate the Central Andes with relative ease. . . . But look, here come our porters. Let's go!'"") She also has Bingham exclaiming on the scenery ("" 'Isn't it fantastic!' Bingham exclaimed. 'It's like seeing the South Pole and the Equator all at one time' ""); and she shows him being driven on by the stirring sentiments of Kipling's ""Explorer."" In that same spirit, as stiffly, Eagle's black-and-white drawings show the explorers in earnest boy-scout poses. His backgrounds are notably unspectacular, though Gemming's effusions and her several-page description of the rediscovered city require far more (preferably photos) to bring the scenes to life. Children studying Machu Picchu might find something of interest in the account, but Gemming hasn't found the voice for her subject that the Epsteins managed so well in their latest contribution to the same Science Discovery series, She Never Looked Back (p. 290, J-78).