Talk:Thomas Hubbard Sumner

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It is not clear exactly what was the DR latitude he used

In his book published in 1843 Sumner says "but feeling doubtful of the Latitude, the observation was tried with a Latitude 10' further N, finding this placed the ship ENE 27 nautical miles, of the former position, it was tried again with a Latitude 20' N of the dead reckoning; this also placed the ship still further ENE, and still 27 nautical miles further; these three positions were then seen to lie in the direction of Small’s light" but he does not explicitly say what was the original DR latitude he started with.

He does not specify what his DR latitude was in that case but Bowditch says it was 51º 32' and that he used 51º 42' and 51º 52', which puts the last position over land and seems a bit strange. On the other hand Sumner in his book presents an example where he uses 51º 27' as DR latitude in the same location but he does not imply this was what he actually used. GS3 (talk) 21:59, 6 January 2009 (UTC)[reply]

[Presumed] Clarifications Offered

I think (after accidentally adding this to the wrong discussion area) I may have figured out how to add it to the correct talk page for this article. So ... here's what I had typed up earlier:

I apologize for my lack of experience in providing help for Wiki articles and unwillingness to launch into the training, but I’d like to propose some clarifications and suggest the need for a few more to the author, and he/she may do with them what they will. First, a suggested re-write:

Thomas Hubbard Sumner

Thomas Hubbard Sumner (20 March 1807 – 9 March 1876) was a sea captain during the 19th century. He is best known for developing the celestial navigation method known as the Sumner Line or line of position.

Biography

Thomas Hubbard Sumner was born in Boston on March 20, 1807, the son of Thomas Waldron Sumner, an architect, and Elizabeth, daughter of Thomas Hubbard, of Weston Massachusetts. Sumner was one of eleven children, four of whom died young. Of the seven that survived, he was the only son. He entered Harvard at age fifteen.

At age nineteen, shortly after graduating, he married a woman with whom he had become entangled and they moved to New York. The marriage was short-lived, as they were divorced three years later. He then enrolled as a common sailor on a ship engaged in the China trade, and within eight years he had risen to the rank of captain and was master of his own ship. On March 10, 1834 he married Selina Christiana Malcolm, of Connecticut. Together they had six children, between 1835 and 1848, two of whom died in infancy.

On November 25, 1837, Sumner sailed from Charleston, South Carolina, bound for Greenock, Scotland. It was during that voyage, while entering the channel of Saint George and the Irish sea, that he discovered the principle upon which his new method of navigation was based. Perfecting it over the ensuing years, he published it in the form of a short book in 1843.

Shortly after that his mind began to fail, and in 1850 he was committed to the McLean Asylum in Boston. His state of mind gradually deteriorated, and in 1865 he was committed to the Lunatic Hospital at Taunton, Massachusetts, where he died in 1876 at the age of 69.

Two survey ships in the United States Navy, both named the USS Sumner, have been named for him. Also, the Moon’s Sumner crater is named after him.

Discovery

He discovered the basic principle of his new method of navigation while on a voyage from South Carolina to Scotland, in 1837. On December 17, 1837, as he was nearing the coast of Scotland, he was uncertain of his position after several days of cloudy weather and no sights. A momentary opening in the clouds allowed him to take a sight of the sun which he reduced with his estimated latitude but, being uncertain about the latitude, he reduced the sight again using 10' greater and 20' greater latitude and he observed that all three resulting positions were located in a straight line. This line also happened to pass through a lighthouse near the coast. He reasoned that he must be located somewhere along that line, and that if he set course along that line, he should eventually sight the light; which, in fact, he did. He realized that a single observation of the altitude of a celestial body determines the position of a line somewhere on which the observer is located. He called this line a "parallel of equal altitude," which has since been more commonly called a "line of position." Sumner published his findings six years later, in 1843, and this method of resolving a sight for two different latitudes, and drawing a "line of position" through the two positions obtained, was instantly recognized as an important development in celestial navigation. A copy of the pamphlet describing the method was supplied to every ship in the United States Navy.

Further clarification of the celestial navigation terminology used, via links, would also be helpful to those (like me) that are not familiar with it.

Charlie917 (talk) 21:52, 8 May 2010 (UTC)[reply]