Longitude

Just finished reading Longitude by Dava Sobel. We've met her in planets, and Longitude delivered on the high expectations set by the earlier book. The story revolves around the solution of the 'Longitude Problem', namely, determining your longitude in the sea (lattitude could be determined from the elevation of the pole star, which is overhead at the north pole and at the horizon at the equator). This was a pressing issue, a single accident in 1707 due to the miscalculation of longitude turned into loss of four ships and two thousand lives. This led to the Longitude Act of 1714 in UK, where a prize of 20000 pounds was declared for the correct resolution of the problem. The problem could be solved if a clock reliable enough to work accurately in the unsteady sea could be constructed. Then you can set the clock to some known meridian time, take it with you on the ship and compare its reading with the local time. The time difference can be converted to a longitude reading. But constructing such a clock was an undertaking of no small magnitude. Pendulums could not be kept steady in the turbulent sea, temperature differences meant different parts might expand and contract by different amounts, and there was the general problem of reliability (it's a bit hard to appreciate these difficulties in our age of Rs20 digital watches, sold by kilos, and more accurate by orders of magnitude than the best of that era). A self taught clockmaker named John Harrison, using novel techniques invented by himself succeeded (his still surviving masterpieces are named H-1 through H-4), but had to struggle long to claim the prize money because the evaluation committee, composed of Astronomer Royal and other learned men was predisposed towards astronomical solutions and against what 'mechanics' wrought. Especially, Nevil Maskelyne, the fifth A.R. did everything to make Harrison's life miserable [As a side note, Maskelyne was instrumental in establishing Greenwich as the de facto prime meridian which had earlier resided in Rome, Pisa and Paris among other places. And as a side note to this side note, the de facto standard became de jure in the 1884 International Meridian Conference]. But Harrison and his clocks triumphed in the end, and launched into a new era of marine clockmaking and it has been suggested that the source of naval power that made the British empire was this advance in navigation.

Sobel's writing is as is to be expected, wonderful. The Longitude Problem occupied all the great minds of the time including Galileo, Halley, Newton, Hooke and Cassini, but interestingly, we do not hear much about their contributions in this area. I am just glad that I picked this book.

Enjoy!