DEPRECIATION LANDS - WHAT DOES THAT MEAN?

Depreciation Lands? You may have seen this on old Plat Maps or a reference in a Land Grant, Will, or Historical text. (Link now to the Pittsburgh Pennsylvania historical library!) Back during the Revolutionary War, many soldiers were solicited with a promise. If the war was won against Britain, and the land became the property of the fledgling government, the soldiers who could not be paid while active would be paid by being given a tract of land. These lands were granted and are DEPRECIATION LANDS... You see DEPRECIATION LANDS in THE ORIGINAL COLONIES, particularly in "frontier" places like Western Pennsylvania. Now what I wonder is why they weren't called APPRECIATION LANDS!