Descent: a downwards movement, bad for a fragile object falling or a fragile person tripping. A good thing if you descend from an airless mountaintop or from worthy ancestors. It’s especially useful if you need an inexpensive system of water delivery, for even in the desert there’s the free pressure of gravity. The photo here is taken in a desert during World War Two, one of the many photos my father brought back from the Middle East. It’s captioned simply “Gravity Tank”, taken in North Africa, probably Egypt, in about 1941.
Prompted by the WordPress photo challenge.