About half past five
Agriculture and the care of domestic animals by daylight would have to be postponed for some time , possibly for a year or more . Above all , the health of the prospective colonists must be safeguarded . It was not until nearly nightfall of the next day , and after stops had been made at the ruins of two considerable but unidentified towns -- for fuel , as well as to fit up an electric search-light and hooded lamps to illuminate the instruments in the Abyss -- that the explorers found what they were seeking . About half past five that afternoon they sighted a very considerable river , flowing westward down a rugged and irregular valley , in the direction of the chasm . `` This ca n't be the Ohio , '' judged Stern . `` We must have long since passed its bed , now probably dried up . I do n't remember any such hilly region as this in the old days along the Mississippi Valley .