Martina ‘s Mariner’s Astrolabe
The mariner’s astrolabe was a navigational device that was extensively used at sea from 1460 through to the eighteenth century. Comparing it to the more ornamented, exuberantly detailed astrolabes at the time, the mariner’s astrolabe is much simpler. Made to withstand the harsh conditions on a ship, its functional based design consisted of a heavy brass material and perforations in its base plate to let the wind pass through. Stripped of the complex scales and stereographic projections, it contained only a simple graduated scale in degrees and an alidade for measuring the altitude of the sun or for sighting stars.
How to measure the height of the sun / star:
- Hold the astrolabe at eye level
- Rotate the alidade and aline it with the sun or north star
- The angle noted is the angle above the horizon thereby giving the ships latitude
How to measure the height of a building: