However, while being nursed back to strength, the scientist managed to make out that his rescuers were political refugees from another city in the heart of the mountains known as Athensi, and that in this city and the plateaus surrounding it dwelt a white race of semi-civilized people ruled over by a religious Oligarchy. His rescuers were men of superior intelligence and a high state of culture and that they had travelled about the world was apparent. With his slight knowledge of English and a smattering of their tongue which he picked up, he was able to come to that conclusion. To him it became apparent that the ruined city of Korakum, overgrown by rank jungle growth and in the midst of which the Athensian exiles cultivated little patches of garden, was the city he had been seeking. But the little he could learn of Athensi fired his imagination. Apparently, at some dim age in the past the settlers of this ruined city which had been called Korakum had withdrawn into the mountain country and built Athensi, where were palaces, temples, a vast Coliseum, above all, a great Library housing thousands of papyrus rolls. If he could only gain access to Athensi, thought Professor Souchard, what wonders and mysteries of the ancient world, perhaps of a civilization existing in Atlantis before the Flood, would be revealed. However, on his recovery, the exiles told him it was best for him to depart before the Athensian authorities discovered his presence, as they wished to preserve isolation from the outside world and did not want their secret discovered. Therefore, after supplying him with water and food, they started him and Ben Hassim on the return journey. Well did Jack recall the arrival of Professor Souchard at his father’s home on Long Island with this tale. Mr. Hampton, himself an explorer and engineer of wide reputation, had been enthusiastic. He had promised the scientist, whose funds had become exhausted and who was unable to obtain backing for further explorations in war-exhausted Europe, to finance an expedition to Athensi. With this promise, Professor Souchard had returned to Africa, and as soon as he could put his affairs in shape for prolonged absence, Mr. Hampton had followed. With him he had taken Jack and the latter’s close chums, Bob Temple and Frank Merrick. Those of our readers familiar with the three Radio Boys by reason of following their adventures chronicled in “The Radio Boys on the Mexican Border,” “With the Revenue Guards,” “On Secret Service Duty,” “In Search of the Inca Treasure” and “Rescuing the Lost Expedition,” will realize that three more reliable young fellows in just such a situation could not be found.