The Longitude Problem

Date: 01 Oct 2023

I recently read this book called “Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time” by Dava Sobel.

To be honest, I never thought that finding longitude was a big thing back then but I always had a weird interest about timezones which pushed me to read this book. The ship navigation heavily depends on finding the longitudes thus location of the destinations. This book talks about this exact problem, the 1714 Longitude act (link) passed by the English empire, how the Royal society is involved in this, the politics involved in judging various solutions, how Lunar distance was considerd to be the best approach in determining longitudes for quite sometime and about this person named “James Harrison” who invented devices (to be precise 4 models out of which the last one is a hand-held clock) and laid solid foundation for the instrument called chronometer. This book also brings in the Sextant which was invented in the process of solving the longitude problem. These both devices are still used by ships today to navigate in the ocean even in the age of satellite based navigation systems.

This book covers various proposed solutions like star positions w.r.t Jupiter, position markings of more than 100 stars in the sky, the lunar distance etc, and their flaws w.r.t the pressure, sensitivity and heavy dependency on a clear sky to look for the position of stars. James Harrison’s story itself is really interesting and this book talks about his lifestyle in general and how a carpenter like himself solved one of the greatest problems in history while people from the Royal society and great scientists with many resources couldn’t provide a solid solution. This book also brings in people like Sir Issac Newton, Galileo Galilei, King George III and other interesting people.

Something that triggered my memory is St.Helena, an island very well known for Napolean Bonaparte. But after reading this book, I found out that this same island stands on IST (International Standard Time) and credit goes to this person named “Nevil Maskelyne”. There is a good amount of info on him in this book and he is the main person who pushed for Lunar distance method to calculated longitudes. He used to publish this newsletter regularly where the lunar distances are updated (?) and everytime Greenwich (that’s where the Royal observatory is) is taken as reference. Even though this method is not used anymore but since many got used to the reference location, GMT is majorily accepted (there was a convention too in US where everyone voted for this) as a reference timezone (UTC + 0.00). The explanation around this topic is really good in this book and I might have mixed up a few things so do read it for clear info.

Here is the page that also talks about the timezone - https://sainthelenaisland.info/time.htm