You are right now, replied Webb.
But how did you know it wasn’t right? You stood behind the compass, but did not look through it.
I knew it by that tall pine tree on top of yonder hill. I discovered a mile back that the tree was exactly in line, and if you will look back, you will see a dead hemlock tree, with the bark off. By noticing objects both ahead and behind, you can detect the least variation.
Walter comprehended the explanation.
If I understand you, the needle must set on the figures 45°, W., and looking forward through the slots, the eye must strike the staff and pine tree, and looking back, the hemlock tree must be in line exactly.
Right boy. Now move on to the flag and take a new sight.
The compass was set at the next station by Walter, with great care. Before him, he could see the staff and pine tree, and behind he could see the dead hemlock.
Well done, boy! exclaimed Webb. You have mastered your first lesson. You can take charge of the instrument now for the season. We shall run this course for the next month, then we will go into winter quarters, and you can go into the books, and by spring, you can take charge of the survey.
Walter’s eyes glistened with satisfaction, both for the praise and promises of his employer. From this time to the close of the season, Walter took charge of the work, and gave entire satisfaction to his employer.
About the first of November, they went on board a flat-boat and floated down the Delaware. Amy, Walter’s cat, accompanied them. They arrived at Philadelphia on the fifth day, and immediately proceeded to the residence of Mr. Webb, where Walter was well received and kindly treated, and at once commenced his school days, and earnestly studied mathematics, geometry and trigonometry. He threw his whole soul into his studies, and worked night and day to solve the difficult problems. Although he was in a city of fashion, he could not be induced to enter society. His books and Amy were his only companions.