David Barrie

David Barrie

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Battleship USS Alaska's Chief Quartermaster John P. Overholt took a sun sighting with a sextant, off Iwo Jima, 6 Mar 1945; taking notes on the observations was QM3/c Clark R. Bartholomew. (US National Archives)

Battleship USS Alaska's Chief Quartermaster John P. Overholt took a sun sighting with a sextant, off Iwo Jima, 6 Mar taking notes on the observations was Clark R. (US National Archives)

Ball's Pyramid, Lord Howe Island, Australia, the tallest volcanic seastack in the world #travel #places

Ball Pyramid - the world’s tallest sea stack. It is the remains of a shield volcano formed about 7 million years ago, located southeast of Lord Howe Island in the Pacific Ocean. Ball's Pyramid is part of the Lord Howe Island Marine Park in Australia.

Galileo's jovilabe, 17th century Florence, Istituto e Museo di Storia della Scienza, inv. 3178  This instrument was designed to calculate the periods of Jupiter's moons. It is a complex analogue calculator whose use, Galileo argued, would allow navigators to determine longitude at sea.

Galileo's jovilabe, century Florence, Istituto e Museo di Storia della Scienza, inv. 3178 This instrument was designed to calculate the periods of Jupiter's moons. It is a complex analogue calculator to allow navigators to determine longitude at sea.

The backstaff was invented in 1594 by an English navigator John Davis and he got the idea from the quadrant. It is a navigational instrument that was used to measure the altitude of the celestial body, most likely the sun or the moon. While observing the sun, the person using the quadrant would keep the sun to their back and they would observe the shadow casted by the upper vane on a horizon vane to find the altitude. It was also the predecessor to the octant.

Davis Quadrant or Bakstaff from the XVIII century, used to mesure the altitude of the sun over the horizon. This model uses no mirrors just the sun's shadow on the limb besides the slot to view the horizon.

Napoleon's sextant.

Napoleon's sextant.

Agnes Tapley sailed with her husband aboard the bark Saint James during the late 19th century. Some women like her learned navigation from their husbands while at sea.

Taking Sight Using a Sextant, Mrs. Tapley taking a sight using a sextant. She sailed with her husband aboard the bark Saint James during the late century. Some women learned navigation from their husbands while at sea.

Patroi hondarribitarra eguerdian eguzkiaren alturea hartzen. Patrón hondarribitarra observando el sol al mediodía

Patrón hondarribitarra observando el sol al mediodía

A woman on the deck of a ship at sea taking a sight with a sextant.

Taking Sight Using a Sextant, Mrs. Tapley taking a sight using a sextant. She sailed with her husband aboard the bark Saint James during the late century. Some women learned navigation from their husbands while at sea.

Battleship USS Alaska's Chief Quartermaster John P. Overholt took a sun sighting with a sextant, off Iwo Jima, 6 Mar 1945; taking notes on the observations was QM3/c Clark R. Bartholomew (US National Archives)

Battleship USS Alaska's Chief Quartermaster John P. Overholt took a sun sighting with a sextant, off Iwo Jima, 6 Mar taking notes on the observations was Clark R. (US National Archives)

Mariner’s Sextant

A sextant is a marine navigation instrument which is used to measure the angle between two objects. Sextant is still used on many ships around the world.

September 1942. "Learning how to determine latitude by using a sextant is Senta Osoling, student at Polytechnic High School, Los Angeles. Navigation classes are part of the school's program for training its students for specific contributions to the war effort."

1942 Learning how to determine latitude by using a sextant is Senta Osoling, student at Polytechnic High School, Los Angeles, Calif. Navigation classes are part of the school's program for training its students for specific.