Posted October 26, 201410 yr comment_250 1 - Pacing Permissible error ≤ 1 feet in 20 feet. 2 - Chain Permissible error ≤ 1 in 1000. 3 - Metallic Tape Permissible error ≤ 1 in 1000. 4 - Steel Tape This tape is made of steel alloy of very small co-efficient of thermal expansion. Permissible error ≤ 1 in 1000. 5 - Invar Tape This tape is made of very expensive steel alloy of almost negligible co-efficient of thermal expansion and is used for very precise linear measurements. Permissible error ≤ 1 in 50,000. 6 - Techometry Permissible error ≤ 1 in 50,000. 7 - Electronic Distance Meter Permissible error ≤ 1 in 100,000.
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