Re: What is Compass ?

Wed Jan 09, 2019 12:48 pm

Chinese scientists may have known that rubbing an iron bar (such as a needle) with a naturally occurring magnet,

Wed Jan 09, 2019 12:48 pm

called a lodestone, would temporarily magnetize the needle so that it would point north and south.

Wed Jan 09, 2019 12:49 pm

Very early compasses were made of a magnetized needle attached to a piece of wood or cork that floated freely in a dish of water.

Wed Jan 09, 2019 12:49 pm

As the needle would settle, the marked end would point toward magnetic north.

Wed Jan 09, 2019 12:49 pm

As engineers and scientists learned more about magnetism,

Wed Jan 09, 2019 12:49 pm

the compass needle was mounted and placed in the middle of a card that showed the cardinal directions—

Wed Jan 09, 2019 12:49 pm

north, south, east, and west. A spearhead and the letter T, which stood for the Latin name of the North Wind,....

Wed Jan 09, 2019 12:50 pm

Tramontana, signified north. This combination evolved into a fleur-de-lis design, which can still be seen today.

Wed Jan 09, 2019 12:50 pm

All 32 points of direction were eventually added to the compass card.

Wed Jan 09, 2019 12:50 pm

Historians think China may have been the first civilization to develop a magnetic compass that could be used for navigation.

Wed Jan 09, 2019 12:50 pm

Chinese scientists may have developed navigational compasses as early as the 11th or 12th century. Western Europeans soon followed at the end of the 12th century.

Wed Jan 09, 2019 12:51 pm

In their earliest use, compasses were likely used as backups for when the sun, stars, or other landmarks could not be seen.

Wed Jan 09, 2019 12:51 pm

Eventually, as compasses became more reliable and more explorers understood how to read them, the devices became a critical navigational tool.

Wed Jan 09, 2019 12:52 pm

By the 15th century, explorers realized that the “north” indicated by a compass was not the same as Earth’s true geographic north.

Wed Jan 09, 2019 12:52 pm

This discrepancy between magnetic north and true north is called variation (by mariners or pilots) or magnetic declination (by land navigators) and varies depending on location.

Wed Jan 09, 2019 12:53 pm

Variation is not significant when using magnetic compasses near the Equator, but closer to the North and South Poles, the difference is much greater and can lead someone many kilometers off-course. Navigators must adjust their compass readings to account for variation.

Wed Jan 09, 2019 12:53 pm

Other adaptations have been made to magnetic compasses over time, especially for their use in marine navigation.

Wed Jan 09, 2019 12:53 pm

This article is about the direction finding instrument used in navigation. For other uses, see Compass (disambiguation).

Wed Jan 09, 2019 12:53 pm

When ships evolved from being made of wood to being made of iron and steel, the magnetism of the ship affected compass readings.

Wed Jan 09, 2019 12:53 pm

This difference is called deviation. Adjustments such as placing soft iron balls (called Kelvin spheres) and

Wed Jan 09, 2019 12:54 pm

A compass is an instrument used for navigation and orientation that shows direction relative to the geographic cardinal

Wed Jan 09, 2019 12:54 pm

bar magnets (called Flinders bars) near the compass helped increase the accuracy of the readings.

Wed Jan 09, 2019 12:54 pm

directions (or points). Usually, a diagram called a compass rose shows the directions north, south, east, and west on the

Wed Jan 09, 2019 12:54 pm

Deviation must also be taken into account on aircraft using compasses, due to the metal in the construction of an airplane.

Wed Jan 09, 2019 12:54 pm

compass face as abbreviated initials. When the compass is used, the rose can be aligned with the corresponding geographic