Longitude

London offers such a concentration of museums, brimming with objects “collected” from all over the world. And all the museums in London are free – sometimes special exhibitions have entry fees, but day in, day out, you can travel the globe with an Oyster Pass (the amazingly convenient plastic card you swipe on a pad at Underground or on a bus to ride).

Much as I love revisiting favorites in London, we discovered someplace new to us but very old, on our Greenwich day. After visiting the Royal Maritime Museum, we climbed a hill rising from green parkland to the Royal Observatory. It’s a beautiful spot, capped by Flamsteed House where a reddish-orange ball on a mast still rises and falls to mark 1 p.m. – as it has every day since 1833, so mariners on ships in the nearby Thames could set their clocks. Modern timekeeping methods make the orange ball obsolete, it rises and falls now for tradition.

The museum inside Flamsteed House is much about time, longitude, and the competition to solve the navigational problem plaguing mariners of old – without accurate charts, ships foundered and many seamen lost their lives, countries lost their ships.

Our younger son and his sweet bride studied an enormous globe, finding Thailand (such a long way and across the International Date Line), and trying to really understand geography and time. Latitude is easier to get, as it was in the past, but figuring longitude, the invisible lines running up and down on our globe is trickier – and vital.

In her book, “Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time” Dava Sobel says: “The zero-degree parallel of latitude is fixed by the laws of nature, while the zero-degree meridian of longitude shifts like the sands of time. This difference makes finding latitude child’s play, and turns the determination of longitude, especially at sea, into an adult dilemma – one that stumped the wisest minds of the world for the better part of human history.”

To know longitude at sea, one must know the time aboard ship, and the time at a known longitude. Sobel writes: “Precise knowledge of the hour in two different places at once – a longitude prerequisite so easily accessible today from any pair of cheap wristwatches – was utterly unattainable up to and including the era of pendulum clocks.”

Sobel’s fascinating book traces the competition and surprisingly underhanded maneuvers involved in finding a method to determine time at sea. She writes about early attempts at solutions, involving the stars, the moon, even the yelps of wounded dogs.

At the museum we saw the work of the creative scientist John Harrison, a “mechanical genius,” who, after devoting his life to the quest, invented “portable precision timekeeping devices” – clocks unaffected by the a ship’s rocking motion. Sobel tells the story of the stubborn, almost malevolent, scientific elite who distrusted his invention – men who refused to accept a new way.

The Observatory is also the site of the Prime Meridian, longitude’s starting point, and the line from which we measure Coordinated Universal Time – sometimes called Greenwich time.

As the wordsmith predicted, it would have been a tourist thrill to stand on the Prime Meridian itself, but we just hovered in the vicinity watching a long line of tourists waiting for their moment to straddle east and west.

Visiting Greenwich provided a day out of time to consider the time before people weren’t so cavalier about being at the same moment, if not the hour, as the rest of the world.

not a chronometer, but-1

5 thoughts on “Longitude

  1. I would have liked seeing that orange ball. Time is such a fascinating subject – so definite and yet so hard to really, really understand. Thanks for reminding me of the Sobel book. I read it thinking about my brother who spends his days with antique clocks and antique time. The clocks in early America were at once amazingly simple and amazingly complicatd with their lovely brass hands, wooden gears, face paintings, little engravings or the sun and moon. They make our digital time seem so very dull.

    • John Harrison’s chronometers were very intricate and beautiful also – and the one solving the problem was small compared to his first attempts (but not compared to the watches sailors wear now).

  2. A timely post—my plastic wristwatch is in need of a battery today and I’m completely lost without it! This made me realize how I take the telling of time so for granted. Thanks Katy.

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