What Were Cross-staff Used For?

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What were cross-staff used for?

The cross-staff is an instrument used to measure angles and altitudes, consisting of a trigonometrically graduated staff and one or more perpendicular vanes moving over it.

What replaced the cross-staff?

In many cases, John Davis’s invention ended up replacing not only the cross staff, but also the mariner’s astrolabe and quadrant. It was in the late 1700s when the octant and sextant became the new preferred tools over the back staff.

Who invented Jacobs staff?

The original Jacob’s staff, or cross-staff, was a single pole device credited to Levi ben Gerson (1288-1344), who was one of the leading Jewish mathematicians of the 14th century.

When was the back and cross-staff invented?

Thomas Hood invented this cross-staff in 1590. It could be used for surveying, astronomy or other geometric problems. It consists of two components, a transom and a yard.

How old is the cross-staff?

Early descriptions of the cross-staff date back to 11th century Persia. As trade between Europe and Asia grew, new ideas were brought back to Europe, and became popular there. While the concept of the cross-staff was known by the 15th century, it was not until the 16th century that the tool became more widely used.

What is a cross-staff on a boat?

: an instrument formerly used at sea for taking the altitude of a celestial body.

What is Abney level in surveying?

: a surveying clinometer consisting of a short telescope, bubble tube, and graduated vertical arc used especially for measuring tree heights.

What is Open cross staff?

The Open cross-staff consists of a long staff with a perpendicular vane which slides to and fro upon it. These open frame tripods are comes with lemon yellow powder coated and silver anodized. Features: Used to measure the altitude of the sun. Used as a navigation instrument.

What is Jacob’s Rod?

In surveying. In surveying, a jacob staff is a single straight rod or staff made of nonferrous material, pointed and metal-clad at the bottom for penetrating the ground. … This device was used by surveyors to measure offsets.

What is French Cross staff?

French Cross Staff:

French cross-staff consists of an octagonal brass tube with slits on all the eight sides and on each of four sides, it has an alternate vertical sighting slit and an opposite vertical window with a vertical fine wire. For setting out right angles, these are used and sights are about 8 cm.

How was the cross-staff used with stars?

Astronomers used the cross-staff for measuring the angle between the directions of two stars. … Ships’ officers used it to measure the elevation angle of the noontime Sun above the horizon, which allowed them to estimate their latitude (see section on navigation).

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How many faces does a French cross-staff?

(ii) French Cross-Staff (Fig.

It consists of an octagonal brass tube with slits on all the eight sides.

What is adjustable cross-staff?

ADJUSTABLE CROSS STAFF: It consists of two cylinders of equal diameter placed one over each another and is used to set of any angle.

How do you read a Cross staff?

The staff reading is the reading on the staff at which the horizontal hair appears to cut the staff. A staff reading consists of 4 digits. The first digit represents the whole number of meters, the second digit represents decimeters, and the third, and fourth digits represent millimeters.

How many types of Cross staff are there?

10. How many types of cross staff are available? Explanation: The three types are open cross staff, French cross staff and adjustable cross staff. Open cross staff has two vertical, opposite slits.

Which Cross staff is more accurate?

An optical square is used for the same purpose as the cross-staff, but it is more accurate.

Who invented the Abney level?

Abney level or clinometer used to measure the amount of incline or decline in the ground. The Abney level was invented by Sir William de Wiveleslie Abney in the 1870s.

Is Abney level is a clinometer?

An Abney level and clinometer, is an instrument used in surveying which consists of a fixed sighting tube, a movable spirit level that is connected to a pointing arm, and a protractor scale. An internal mirror allows the user to see the bubble in the level while sighting a distant target.

What does a quadrant do?

A quadrant is an instrument that is used to measure angles up to 90°. Different versions of this instrument could be used to calculate various readings, such as longitude, latitude, and time of day.

How do you make a Jacob’s staff?

  1. Decide what length you would like the staff to be: 1.0 m or 1.5 m. …
  2. Cut the pipe to be 1 cm LESS than your desired length. …
  3. Place the PVC end caps on either end of the pipe. …
  4. Use the marker and tape measure to mark the pipe at 10 cm increments. …
  5. At alternate intervals on the staff, wrap electrical tape between the notches.

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