Braes of Foss Traditional Geocache
snaik: has been crushed by forestry vehicles
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Cache is a lock and lock container, donated by a gracious local cacher thank you dear.
Cache is situated at the Braes of Foss close to the Maskelyne Memorial. The Reverend Neville Maskelyne, Astronomer Royal, came up with a plan to prove that Newton's Law of Gravity holds for matter on the Earth as well as in the heavens. For this he needed a symmetrical mountain - Schiehallion appeared to be perfect.
Maskelyne argued that if the earth was totally smooth, then a plumb line would point down towards the centre of the earth because of the force of gravity on the bob. But if there was a pimple on the earths surface (a mountain) then gravity would pull the plumb line very slightly towards it.
Over a period of four months, he and his colleagues camped out on Schiehallion - first on the south side then on the north - collecting data on the apparent altitude of the stars. If gravity did exist, then when Maskelyne was taking measurements on the south side of the hill, the plumb line should be deflected towards the north effectively decreasing the apparent altitude of the stars. The opposite should occur when he was on the north side of the hill. The difference between the two sets of readings would be the gravitational pull of the mountain.
Two hundred and thirty-seven measurements and many calculations later Maskelyne discovered that the mountain did in fact have a gravitational pull on the plumb line of 11.7 seconds of arc.
The surveyors took thousands of measurements to determine the relative volumes and positions of the mountains. Charles Hutton was a leading figure in analysing this data, and as part of this he divided the landscape into a number of vertical pillars around the observatories, thus inventing the concept of contour lines - essential to modern hillwalkers!
Additional Hints
(Decrypt)
Onfr bs ynetrfg srapr cbfg, ybbx yvxr vg jnf na byq gryrtencu cbyr ahzoref 20 ba vg