He placed a pole perfectly upright in the ground to make a simple sundial, or gnomon .
He also probably introduced the gnomon (a perpendicular sun-dial) into Greece and erected one in Sparta.
When the gnomon is turned up, it can measure height; when it is turned over, it can measure depth and when it lies horizontally it can measure distance.
To ensure that the sundial registered roughly the correct time all the year round the gnomon had to be set at exactly the correct angle.
The problem is that the gardeners have been caught on the gnomon of their own sundial.
The videos were projected onto two screens built to replicate the gnomonic and ‘Robinson projections’ of representing the globe on a two dimensional surface.
On the gnomonic projection, the landing site is approaching and the surface features become sharper.
It failed to use gnomonic charts for its bearings and the King George V was given the position of the Bismarck but it was 200 miles out.
A gnomonic image, meanwhile, tends to make the surface appear flat, and is used by navigators and aviators in determining the shortest distance between two points.
Revolve the gnomon about its vertex and it can draw a circle; combine two gnomons and they form a square.