Christopher Columbus

Christopher Columbus used a lot of different navigational tools. He used magnetic compasses, nocturnals, maps, charts, celestial navigation, quadrants, and sand glasses.

The Quadrant

• The quadrant was originally used by astrologers to determine an eclipse of the sun. It was a device for measuring the angular height of stars or the sun.
• Sailors used it to measure the height of the Polaris, or North Star. They learned from the Arabs that the height of the Polaris above the horizon changes depending on a persons Latitude, the distance above or below the equator.

The Sandglass

• The sandglass is also known as an hour glass, sand timer, or sand clock. It is used as a measurement for time. It is made of two glass bulbs that are placed with one above the other, and connected by a narrow tube.
• One bulb is filled with sand, which flows through the narrow tube, into the other bulb at a given rate. When all the sand has reached the bottom of one the bulbs, it can be inverted to measure time again. The sandglass has a running time of 1 hour.

The Nocturnal

• The nocturnal was a navigational tool used to tell time by the celestial clock, or stars. One ring was set to the date, the Polaris was sighted through the hole in the center, and the arm was swung around to align with pointer stars - stars in the Big Dipper, Little Dipper, or Cassiopeia.
• Where the arm crossed the marked ring, the time was read. The device was also used to measure Polaris's distance in minutes of arc from north so a correction could be applied to it.

Magnetic Compass

• The Polaris served as the seaman's lodestar, or the star that shows the way.
• The magnetic stone, which was used to magnetize the compass needle, was called a lodestone.