eleven o'clock
`` There can not be many caves , '' concluded the professor , `` with entrances high above the ground as this one is described to be . '' The following morning , the day being Sunday , was spent quietly on shipboard . It had been the custom of the professor since the commencement of the voyage to have such observances of the day as seemed fitting . There was a service which he himself conducted at eleven o'clock . Thereafter , all who wished were this day allowed to go on shore . Of the Frontier Boys , Jim and Juarez early in the afternoon availed themselves of the privilege . Juarez was the only one , however , to wander away from the landing beach .