The wooden pinhole camera is in the bottom left hand corner of this image.
We'd rather assumed we'd have the summit to ourselves, but clearly others had also thought of walking on the solstice too so at 1am were awoken by two walkers passing close by along the ridge. They found a spot maybe 50m away from us, but in the cold wind, and without sleeping bags, froze and left as soon as the dawn came.
Schiehallion's isolated position and regular shape led it to be selected by Charles Mason for a ground-breaking experiment to estimate the mass of the earth in 1774. The deflection of a pendulum by the mass of the mountain provided an estimate of the mean density of the Earth, from which its mass and a value for Newton's Gravitational constant G could be deduced. Mason turned down a commission to carry out the work and it was instead coordinated by Astronomer Royal, Nevil Maskelyne. He was assisted in the task by mathematician Charles Hutton, who devised a graphical system to represent large volumes of surveyed heights, later known as contour lines, which we now all use on our OS maps.
Ours was another act of measurement, but this time of light and duration.
|Image made from the pinhole camera facing North|
|Image made from the pinhole camera facing South|
We seem to be making a bit of a regular thing of walking at the pivotal points of the years cycles of light and dark.