Longitude – Dava Sobel – Review

For millennium before the mid 19th century, every great captain lost himself in the middle of sea despite the best of charts and compass, eventually leading to heavy loss of life, commodities and in many cases shipwrecks.  There has been hundreds of shipwrecks causing thousands of men ranging from sailors, civilians and warriors who had lost their life in mid sea not having a clue about their whereabouts. It’s one of the prime reasons why many voyagers landed in completely different geographic landmass, the problem of an unclear longitude.

Deep sea or oceans brings with it extreme variances of temperature which caused the lubricating oil within the clocks to thicken or thin down the volume along with expansion or contraction of various components within the clock. It meant that the time shown in clocks became unreliable with differences ranging for a few hours ahead or behind the actual time, mostly not even knowing whether the error in time difference is positive or negative. Now why is it so devastating, just a change in 1 degree longitude which corresponds to an hour, roughly translates to 1000 nautical miles near the equator. No wonder many brave sailors and captains drowned or got lost in mid sea.

In the absence of a reliable timekeeping machine which is technically termed as chronometer, the common practice was to rely on the clue garnered from celestial bodies. The lunar-solar distance during day time and lunar-stellar distance on night time were extensively studied and mapped by many astronomers, which formally got published as nautical almanac in the second half of 18^th century, there have been remarkable individuals who had spent over 4 decades in trying to map down a database of various assembly of stars, formally known as constellations. 

The broad idea is to pick a pattern from the celestial bodies during different seasons which would eventually lead to a reliable solution towards identifying longitude. However, the observations happened from a stationary point on a specific geographic location, using them in a moving ship sailing across continents proved to be confusing in mid sea, add cloud cover and heavy rain to the mix, we now have captains banking purely on chance. We have heard stories of how Columbus wanted to sail far east and land in India but ended up in America that's in the west. 

The imperial British government sensing the gravity of the problem setup board of longitude in the early 18^th century, announcing an award of 20,000 pounds to anyone who could unearth a method to find longitude within 30 nautical miles, the prize amount could well be worth over 3 million pounds by current valuations. Scores of people pitched in with ineffective or myopic solutions but one man spent over five decades determined to innovate an accurate timekeeping machine. He is John Harrison (1693-1776), a carpenter by his lineage and a self-taught horologist who discovered an out of the world device and solved a perennial perplexing problem of longitude.

Dava Sobel’s book on Longitude covers John’s story and his life long trials to not just discover the device but having to endure contrary motives of a bunch of key personnel in the respective governing body of imperial Britain. To put it more crisply, there is an established villain portrayed against John in Dava’s narrative as well.

The book brings to light how much innovators had to endure to earn their recognition beyond the taxing trials of an abstract solution.