To accompany a major exhibition, Spain in the Age of Exploration, 1492-1819, the Seattle Art Museum (SAM) presents this interactive website that illustrates the use of four ancient nautical instruments: the Quadrant, Asrolabe, Octant, and Chronometer. Each instrument's section includes pictures, a bit of history, and a description of how it was used. For example, the astrolabe was originally devised by Persian astronomers, and is used to determine latitude at sea by measuring the angle of the sun or other stars. In addition, the site includes an early map of North America (1730) and a movie showing David Burch from the Starpath School of Navigation, demonstrating the use of an octant.