Post by washi on Jun 30, 2015 4:33:01 GMT
Today, June 30, 2015, is a leap second day. Tonight, in the last minute of the last hour, an additional second will be added to clocks all over the world. Today could be the last leap second days, as there are other, less disruptive ways of keeping solar time aligned to the gradually slowing rotation the earth. (The computer that keep track of time at the Japanese Stock Exchange, for example, will cut that extra second into 72,000 equal parts, and add them to each second over a period of 2 hours. Google used this "smearing" technique in the last leap second day in 2012, but today is the first time the extra second has been inserted into a day when the world markets are open since electronic trading revolutionized the economic world, and particularly with the current Euro crisis, it is good that Japan and other Asian exchanges are preparing for the worst.)
So another leap second day will probably come and go without most of us needing to think about it at all, but it's certainly, at least, an interesting curiosity, and thinking about the precise measurement of time got me to thinking about John Harrison, to my mind one of the great heroes of the modern age. I took a few hours to watch a couple of TV programs available on You Tube. I assume that many of the membership here in the GEC share my veneration, and since it is now easy to do, I'm posting both videos here for anyone who doesn't know of their existence.
John Harrison in Wikipedia
Rupert Gould in Wikipedia
Rupert Thomas Gould in the Epsom and Ewell History Explorer
Longitude TV Series in Wikipedia
I suppose that a GEC post ought to have some kind of KMZ attached to it, so I'm attaching a placemark on the old Royal Observatory at Greenwich (now part of the National Maritime Museum), where until recently the first four of Harrison's five chronometers were on display. I've also put a placemark on Barrow upon Humber, the small village where Harrison lived most of his life.
The Seconds of John Harrison.kmz (1.96 KB)