Herefordshire acre

In Herefordshire, England, a unit of land area, = 3226 2/3 square yards, based on a perch of 13½ feet.

John Chalmers Morton.
A cyclopedia of agriculture, practical and scientific: in which the theory, the art, and the business of farming are thoroughly and practically treated. Vol. 2.
Glasgow: Blackie and Son, 1855.
Page 938.