Captain Thomas Hubbard Sumner, 30 years old, commanding the sailing ship Cabot, travelling from Charleston, Virginia, to Greenock, Scotland, makes a practical discovery. Smalls Lighthouse where Sumner landed Due to constant bad weather all along his journey, he has navigated on a dead reckoning basis until he finally encounters a piece of blue sky which gives him sight of the sun. He uses the altitude of the sun to make a calculation of longitude based on his estimated latit
