Benchmark on a milestone at Whinlatter

Before there were trig points on hill tops, there were benchmarks. The up arrow points to the level line. They started with an agreed place that was at sea level and worked by the process of levelling from one benchmark line to the next https://en.wikipedia.org/wiki/Levelling Originally, Victoria Dock in Liverpool was the defined sea level but after 1921, it moved to Newlyn in Cornwall - and then sea level was fixed there between 1915 and 1921. It won't be the same now! https://en.wikipedia.org/wiki/Ordnance_datum This benchmark is defined relative to Cockermouth. In 1899, it was 834.9 feet above Victoria Dock, Liverpool. This must have been from a chain of measurements over 100 miles. To be to one decimal place after that distance, the uncertainty in each measurement must have been very small. https://www.bench-marks.org.uk/bm65397