Gilpin, in his account of the forest borderers of England, says that "the encroachments of trespassers, and the houses and fences thus raised on the borders of the forest," were "considered as great nuisances by the old forest law, and were severely punished under the name of purprestures, as tending ad terrorem ferarum--ad nocumentum forestae, etc.," to the frightening of the game and the detriment of the forest.