7. The Sextant, the instrument that mapped the world
The great enigma of technology and engineering is the serendipitous way certain threads of thought and development have coalesced, almost by accident, into epoch-changing innovations. The sextant is, in fact, a straightforward device designed to measure the angle of a particular star from a fixed point at a specific time. Notwithstanding that a reliably accurate chronograph must be available to know that time, thousands of years of astrological observation were required, so that astrological charts could be prepared to display that necessary information upon which it was all based.
So yes indeed, the sextant was one of the great developments of the age, even though it is nothing more than a simple means of interpreting information gathered over the entire human cognitive experience. In the age of at-a-glance GPS readings on a personal device, it is easy to forget the precision and artistry that went into every individual reading that defined the maps of the world.
The construction of a sextant is simply an aperture through which a star is located, and a weighted arm that always points to the place upon which the navigator stands. When a line of sight reading is taken, the angle of the star about the navigator is crossed referenced by time against an astronomical chart. Thus the point at which a person is standing on the surface of the earth can be calculated and pinpointed on a map.