The look of a mountain.Crucially – with neither faint (contour) lines nor numbered heights – we have illustration IX. It probably represents the stage before the invention, on it are marked the perimeter stations – where a theodolite would have been positioned – joined together with bold straight lines.
Giving this illustration its strange target like quality are a series of radial lines and evenly spaced concentric circles which, I imagine outline his ‘columns’.
The mass of wee dots represent a position in which a pole-bearer stood while traversing a – usually – straight line up the mountain. Some are obvious ascents; between A (Creag an Eara) and N (the summit) are 13 dots, thirteen times that poor lad set down his load to hold up a pole while the distant and static surveyor took readings. Cloud rolls in so fast and low, one wonders how often his slow ascents were rendered redundant. In 4 months, those climbs for the summit were successful on just 4 occasions from: A D G and F’.
Where my maths fails me is understanding the epicentre or bulls-eye of the concentric circles, which is not the summit (N), but rather the Northern Observatory (P), suggesting a second map with the Southern Observatory as bulls-eye. I am omitting the circles from my recreation of Hutton’s map on the grounds I would need two sets: two stones sending out ripples on the pond.Hutton worked everything out from negative figures – the summit of Schiehallion was marked as ‘zero’ (this long before the invention of mean sea level), I have read of a French cartographer who used the same method for estimating the elevation of a fort in Minorca in 1761, but the source is not reliable (according to Josef Konvitz, Hutton is a naturalist, Ancelin is not French, and Marsigli drew 2 isobaths, not one). So as intriguing as Cartography in France 1660 to 1848 is, until I get to Paris to see the map with my own eyes, I am with Hutton on this innovation.