Search results
Results from the WOW.Com Content Network
The backstaff is a navigational instrument that was used to measure the altitude of a celestial body, in particular the Sun or Moon. When observing the Sun, users kept the Sun to their back (hence the name) and observed the shadow cast by the upper vane on a horizon vane.
In navigation the instrument is also called a cross-staff and was used to determine angles, for instance the angle between the horizon and Polaris or the sun to determine a vessel's latitude, or the angle between the top and bottom of an object to determine the distance to said object if its height is known, or the height of the object if its distance is known, or the horizontal angle between ...
Main page; Contents; Current events; Random article; About Wikipedia; Contact us; Help; Learn to edit; Community portal; Recent changes; Upload file
The backstaff, which measures the length of a shadow, was used from the 16th century and saw iterative improvements such as the Davis quadrant. These were in use in parallel with the octant and early sextant ; the sextant eventually displaced the others, and is still used to this day.
Navigators had been able to work out latitude accurately for centuries by measuring the angle of the Sun or a star above the horizon with an instrument such as a backstaff or quadrant. Longitude was more difficult to measure accurately because it requires precise knowledge of the time difference between points on the surface of the Earth.
The son of Willem Fredrik Jacob Mörzer Bruyns, Sr. (1913–1996), a Dutch merchant mariner, and a naval officer (reserve), [1] the young Willem Mörzer Bruyns initially trained as navigation officer at the [Amsterdam Nautical College] (Hogere Zeevaartschool van het Zeemanshuis), Mörzer Bruyns sailed as a junior officer with the Amsterdam-based Netherland Line.
Drawing of a back observation quadrant. This instrument was used in the manner of a backstaff to measure the elevation of the sun by observing the position of a shadow on the instrument. In order to avoid staring into the sun to measure its altitude, navigators could hold the instrument in front of them with the sun to their side.
John Davis (c. 1550 – 29 December 1605) was one of the chief navigators of Queen Elizabeth I of England.He led several voyages to discover the Northwest Passage and served as pilot and captain on both Dutch and English voyages to the East Indies.