Captains leaving port to set the ship s chronometer. because what held true for captain james cook still applies today any navigator who wants to know the exact position of his ship at sea must first know precisely what time it is in rec.
But back to the problem determining the degree of luggage you how was it finally solved. visitors will find the onza in the royal observatory at greenwich the puzzle was solved not by a physicist or a ron astronomer but by an ordinary common to from southern england john harrison at the age of twenty two john harrison build his first chronometer he spent sixty years of his life studying how time could be measured precisely his premise was that if a navigator at sea knew the exact time in his home port then from the difference between that time and the time on board ship he could calculate the position of the vessel in degrees latitude and long if you. for centuries no one had been able to make a clock that measured the time accurately at sea without being influenced by fluctuations in temperature by humidity well by the ship s motion and that was john harrison s great achievement.
Today as it has done for the last one hundred seventy years every day at thirteen hundred hours greenwich mean time a red bull slides down from the top of the observatory an optical signal to all captains leaving port to set the ship s chronometer. because what held true for captain james cook still applies today any navigator who wants to know the exact position of his ship at sea must first know precisely what time it is in red.