Meridian - A meridian in cartography is an imaginary line on the Earth's surface extending from the North Pole to the South Pole, used to measure degrees of longitude. These lines play a critical role in navigation, as they help determine precise locations on a map or globe.

In Depth Explanation of Meridian

The term 'meridian' is derived from the Latin word 'meridies,' meaning 'midday.' This is because the sun reaches its highest point in the sky, or its zenith, when it crosses the local meridian line at a place, essentially indicating noon. The concept of meridians has its roots in ancient Greek geography, though the universally accepted prime meridian, which runs through Greenwich, London, was not established until the late 19th century at the International Meridian Conference in 1884.

While the prime meridian at Greenwich is widely recognized, meridians were used differently across various cultures prior to this standardization. For instance, ancient Chinese and Indian cartographers used their own prime meridians. Although the prime meridian's exact location has been standardized, the use of meridians themselves remains fundamental in modern mapping, GPS technology, and timekeeping systems, unequivocally showing their lasting significance.

A Practical Example of the Meridian

A practical and historically significant example of the use of meridians is the Longitude Act of 1714, which aimed to solve the problem of determining a ship's longitude at sea. John Harrison's development of the marine chronometer, a timekeeping device, was pivotal in this context. With accurate time measurement relative to the prime meridian, navigators could precisely calculate their longitude, revolutionizing oceanic navigation and vastly impacting global trade and exploration.

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