Units: All early surveys were in poles, rods, chains, miles and acres and sections. Lengths: 1 pole = 1 rod = 16.5 feet 1 Chain = 4 poles = 66 feet 1 Mile = 80 chains = 320 poles = 5,280 feet = 1.609 kilometers Area: Acres and sections 1 Acre = 10 sq. chains = 160 sq. poles = 43,560 sq. ft or a sq 208.71 ft on a side 1 section = 1 sq mile = 6400 sq chains = 640 acres A 1/2 mile (160 pole) square = 1/4 section = 160 acres A 12 1/2 mile (1,000 chains) square is exactly (1,000,000 sq chains) 100,000 acres or 156 1/4 sections A 250 chain x 500 chain area is 12,500 acres or 1/8 of 100,000 acres Bearings: Degrees, often to only the nearest degree. Thus huge errors by todays (2006) standards. A one degree error for a 160 pole line gives a lateral error of 2.8 poles (~46 ft)! Most surveyors probably used a compass much smaller in diameter than George Washington's. Magnetic Declination or variation of the compass: Concord Town and St. John's . |