sexta-feira, 1 de abril de 2016

Accurate time at SEA - My favorites quotes from the famous Bowditch

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Navigators have made latitude observations for thousands of years. Accurate declination tables for the Sun have been published for centuries, enabling ancient SEAmen to compute latitude to within 1 or 2 degrees. Those who today determine their latitude by measuring the Sun at their meridian and the altitude of Polaris are using methods well known to 15th century navigators.

A method of finding longitude eluded mariners for centuries. Several solutions independent of time proved too cumbersome. Finding longitude by magnetic variation was tried, but found too inaccurate. The lunar distacnce method, which determines GMT by observing the Moon’s position among the stars, became popular in the 1800s. However, the mathematics required by most of these processes were far above the abilities of the average seaman. It was apparent that the solution lay in keeping accurate time at SEA.

CHAPTER 1. INTRODUCTION TO MARINE NAVIGATION

BOWDITCH

THE AMERICAN PRACTICAL NAVIGATOR



Leia uma explicação para esta série de 30 posts clicando aqui

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