How John Arisson have contributed to the seafaring and to the exploration of the Earth ?

How John Arisson have contributed to the seafaring and to the exploration of the Earth ?

         When a navigator knew the local time from the heavens as well as the reference time in London, he could

figure his time difference with London, and find his longitude. So if they knew their longtitude with the calcul(360°/24 hours=15 so 1 hour correspond at 15°) and the latitude with the stars, they can explore the world but they were a lot of problem like the effects of refraction and parallax.

        John Arisson has been the first person who accomplished what Isaac Newton has feared was impossible : he invented that would carry the true time from the house port like an eternal flame to any remote corner of the world.

        He builts in all five increasingly accurate chronometers and the most famous is the fourth chronometer.

One of the five chronometers was named Marine Timekeeper H1. It was composed of a grass hoper exapement, a bar balance, a lignum vitae bearing, a mainspring, two balances spring, wheel balance, remontoire spring and a caged roller bearing.

        When he has been taken on trial from England to the West Indies, a copy of a chronometer was made for the Captain James Cook on his second travel ant it gave to Cook the desire to begin mapping the Pacific.

        However, he made a special enemy of the Reverend Nevil Maskelyne who is the fifth royal astronomer and he is the one who challenged his claim for the coveted prize of £ 20000, he modifies the rules of the contest to make it as they please and that it is advantageous for them. But the utility and accuracy of Harrison's approach triumphed in the end.

        In 1773, after the personal intervention of king George III, Harisson was awarded the coveted prize of 20,000 £ offered by Parliamant in 1714 for “ascertaining the longitude at sea”.

        But now, today, to know the longitude or latitude we just use the stellite of the G.P.S.

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