1911 Encyclopædia Britannica/Perch (measure)

PERCH (through Fr. perche from Lat. pertica, a pole or rod used for measurement), a bar or rod used for various purposes, as e.g. for a navigation mark in shallow waters, for a support on which a bird may rest, or for a pole which joins the back with the fore part of a wagon or other four-wheeled vehicle. As a term of linear measurement, “perch,” also “rod” or “pole,”＝161/2 ft., 55 yds; of superficial area,＝301/4 sq. yds.; 160 perches＝1 acre. As a stonemason’s measure, a “perch”＝1 linear perch in length by 11/2 ft. in breadth and 1 ft. in thickness.