Principal Triangulation of Great Britain - Baseline Measurement

Baseline Measurement

The original base-line across Hounslow Heath was measured with deal rods and iron bars to be 27,404 ft. When it was re-measured with 1,370 placements of glass tubes as 27,406 ft. This was corrected for temperature and mean sea-level, and the value and achieved accuracy of 1 inch in 27,404 ft is 3 parts per million.

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