Glen did see, the next day, and wondered at the simplicity of the operation. The front flag was sent across the river in a boat, and on the opposite side he drove a stake. While he was thus engaged, a line a quarter of a mile long was measured on the bank where the rest of the party still remained, and a stake was driven at each end of it. The transit was set up over one of these stakes, and its telescope was pointed first at the other and then at the one across the river, by which means the angle where it stood was taken. It was then set over the stake at the other end of the measured line, and that angle was also taken. Then Mr. Hobart drew, on a leaf of his transit-book, a triangle, of which the base represented the line measured between the two stakes on his side of the river, and one side represented the distance across the river that he wished to find. He thus had one side and two angles of a triangle given to find one of the other two sides, and he solved the problem as easily as any boy or girl of the trigonometry-class can whose time in school has not been wasted as Glen Eddy's was.