nine o'clock in the morning
Then there was the gradual change in the nature of the vegetation and the character of the scenery as the travellers worked their way upward from the level of the great plains , or pampas , into the mountainous region toward Cuzco , with the ever-increasing difficulties of the navigation , which at length became so great that the canoe had to be abandoned altogether , and the journey continued by land , although they still followed the course of the river as closely as possible , in order that they might always be able to get water , and also because it served them as a guide . But it was not until they had been journeying a full month , after their escape from the Mayubuna , that their next really important adventure befell . They had by this time climbed upward out of the low , hot , tropic forest region , and had attained an altitude at which the climate might almost be described as temperate , where , while the days were still distinctly hot , the nights were cool , sometimes even to the extent of sharpness , and where dense morning-fogs were frequent at that particular period of the year . Those fogs were the cause of much inconvenience and delay to the pair ; for they could neither hunt nor travel in a fog , the result being that they were frequently obliged to remain in camp until eight or nine o'clock in the morning , instead of resuming their journey at daybreak , as had heretofore been their custom . Such was the case on the particular morning when the young Englishmen encountered their next important adventure . The sun had been above the horizon nearly two hours when at length the dense fog which had enveloped their camp cleared sufficiently to permit of their proceeding upon their journey , but it still hung about here and there in heavy wreaths , motionless in the still morning air , when they quite unexpectedly came upon one of the old Peruvian roads constructed by the Incas . This road bore evidences of having at one time been a magnificent highway ; but under the rule of the Spaniards it had been neglected until now it was little more than a sandy track over which Nature was fast resuming her sway .