the Illustrated Longitude

by Dava Sobel
210 pages, Biography/History
Reviewed by Jeanne

An easy, interesting read with clear and colorful illustrations.


Note: This edition was co-written by Dava Sobel and William J. H. Andrews.

Mariners have been able to find latitude, those evenly spaced rings around a globe, for centuries upon centuries, but finding longitude was much more difficult. It is based on time, which, unlike the sun's angle to the earth, was almost impossible to gauge prior to the 18th Century; and seamen's inability to accurately plot their course on the oceans resulted in hundreds of shipwrecks.

Scientists here and there had been trying to discover a reasonable way to chart longitude for a century or more prior to the 1700s, but it was not until the Scilly naval disaster of 1707, in which four warships and over 1,400 men were lost because of a miscalculation, that the race began in earnest. "Longitude" tells the story of clockmaker John Harrison and his struggle to create the perfect time-keeping watch to determine longitude at sea.


Parliament offers a substantial reward for the man who can determine a way of keeping track of longitude, but is then loathe to actually follow through. John Harrison is kept from his rightful reward for many years and his clocks made to undergo rigorous and seemingly pointless tests; other men use a variety of methods in trying to gain the prize, not all of which are morally sound and aboveboard.

Spiritual Content

Psalm 107 ("They that go down to the sea in ships...") is quoted at the beginning of the second chapter. Some people bear the title of "Reverend" because of theological training. Parsonages are mentioned.


The Scilly disaster is described in the second chapter; only two men escaped, including the Admiral, but he was subsequently murdered for a gold ring he wore. Other shipwrecks factor in; the effects of scurvy are described. Several of the paintings in this illustrated edition show ships being pounded by waves and broken up.

Drug and Alcohol Content

Alcohol was the standard drink of this age, though it does not really factor in. Rum and grog were used on shipboard.

Sexual Content


Crude or Profane Language or Content



This is a fascinating history of the development of longitude, whose difficulties few people today realize, and the illustrations brighten the pages and make the descriptions of astronomical charts, scientific instruments, historical figures, and various places clearer. It is an easy read, with large print and the majority of pages often occupied by pictures, and is good for anyone interested in science, the history of the sea, or just history in general.

My only complaint was that I wanted to hear a little more about John Harrison himself than Ms. Sobel gives; however, as the title indicates, the book is not so much about him as it is about longitude itself.

Fun Score: 4.5
Values Score: 4
Written for Age: adult

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