Page:Handbook for Boys.djvu/86

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this on the bank of the river so one side points to some point on the opposite bank. Drive in three pegs to mark the exact points of this triangle (A,B,C). Then move it along the bank until you find a place (F,E,G) where its base is on line with the two pegs, where the base used to be, and one side in line with the point across the river (D). The width of the river is raven eighths of the base of this great triangle.

Another method is by the isosceles triangle. Make a right-angled triangle as above, with sides six, eight, and ten feet (A,B,C); then, after firmly fixing the right angle, cut down the eight-foot side to six feet. and saw off the ten-foot side to fit. Place this with the side D B on the river bank in line sight object (X) across. Put three pegs to mark the three