Home » What I Read

Currently Reading: Longitude

11 January 2007 No Comment

Longitude"The thorniest scientific problem of the eighteenth century was how to determine longitude. Many thousands of lives had been lost at sea over the centuries due to the inability to determine an east-west position. This is the engrossing story of the clockmaker, John "Longitude" Harrison, who solved the problem that Newton and Galileo had failed to conquer, yet claimed only half the promised rich reward."

I’m currently reading this book by Dava Sobel about Longitude (you know those lines that run around the earth from north to south).

Back in the 1600s figuring out what your longitude was of HUGE importance world wide. It meant the difference between whether your shipment made it to its destination (forget "on time", if it got there at all it was a minor miracle). That in turn effected the global economy.

If you were a sailor it could mean the difference between life and death. Literally thousands of ships were lost at sea due to inacurrate navigation through dead-reckoning. If you’re on a ship that doesn’t know it’s longitude you might starve to death when the food runs out. Worse still you might get scurvy from lack of vitamin-C. Scurvy causes your cells to lose their integrity and the cell wall eventually breaks down, spilling the contents of the nucleus. You start out with bruising all over your body. Your gums begin to bleed. Your teeth fall out. Wounds don’t heal. Eventually your entire body bleeds to death.

Latitude (the parallels lines) were easy to figure out using the stars which maintain their positions despite the earth’s rotation. Longitude was a big problem though and because of this a number of different governments setup cash prize to the first person who defined a reliable mechanism to figure it out.

"In July of 1714, during the reign of Queen Anne,  the Longitude Act was passed in response to the Merchants and Seamen petition presented to Westminster Palace in May of 1714.  A prize of £20,000 was offered for a method of determining longitude to an accuracy of half a degree of a great circle."

John Harrison, a brilliant mind with no formal training in watch or clock making figured it out by building a clock that would keep accurate time at sea despite the pitching and rolling of the boat (Pendulums don’t work on boats).

Harrison built 4 models, the final model (the H4) set sail for the Indies on 18 November 1761. They arrived in Jamaica on 19 January 1762 where the clock was found to be about 5 seconds slow!!!
That’s impressive even by today’s standards. My Omega Seamaster GMT [LINK] which is a COSC certified chronometer is reliable to +/- 4 seconds a day. ( Not really a fair comparision as performance with a chronometer typically balances out over time. That is to say the Omega will worsed case lose 4 seconds a day but likely gain those back the next. )

So far I’m finding this an easy read and a fascinating look into some of the real-world problems faced in the "old days".

Leave your response!

Add your comment below, or trackback from your own site. You can also subscribe to these comments via RSS.

Be nice. Keep it clean. Stay on topic. No spam.

You can use these tags:
<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>

This is a Gravatar-enabled weblog. To get your own globally-recognized-avatar, please register at Gravatar.