Seven o'clock in the evening
`` Seven in the evening , '' murmured Frank . `` It must be getting dark outside . '' It had been dark from the beginning in the cave . `` Seven o'clock in the evening , '' went on Andy , `` and we came in here about four ! The tide has several hours to rise yet , and -- '' He did not finish , but he glanced down at the water that was steadily rising up on their legs . It was chilling them , yet they dared not move much for fear of toppling off the narrow ledge . Frank did not answer .