Interesting juxtaposition

One of my bibliographical sins is that of reading many books at the same time. I know there are drawbacks to this but it is a habit I have had from early years and betrays a bookish gluttony.

One of the benefits of this habit though is that it sometimes allows you to make connections you might not otherwise recongnize. I am currently reading, among others, Richard Dana's Two Years Before the Mast as well as Stephen Taylor's Caliban's Shore. In Dana's account, from the 1830's, they are on their return journey from trading on the California coast. They are approaching the area of Cape Horn and he mentions their longitudinal and latitudinal position with precision in the context of anticipating the weather they will encounter. The sailor's concern is clear in the text but it is specific - they fear the storms and the cold of the Horn but they know precisely where they are.

In contrast, aboard the Grosvenor, an East Indiaman returning in 1781 from India to Britain via South Africa's Cape of Good Hope, they have, owing to the lateness of the sailing season, been sailing across the remote stretches of the Indian Ocean without sight of land or ship for six weeks.

Mariners have long known how to measure their latitude (how far north or south they are from the Equator). However, there was no easy or obvious method for determining longitude (how far east or west one was). It was only in the 1750's and 1760's when John Harrison in Britain proposed the use of chronometers and began developing instruments for that purpose. However, in 1781, chronometers were still very expensive, fallible, and rare. Most ships, including the Grosvenor, did not carry chronometers and therefore were unable to determine their longitude other than through dead reckoning which often turned out to be grossly and catastrophically inaccurate.

Such proved the case with the Grosvenor. They have been sailing six weeks across the Indian Ocean, know they are approaching Africa but can't be certain if it is 2, 20, or 200 miles away.

It is interesting to read the two texts in near proximity and see how forty years and one critical technology can make a world of difference. The concern and fear in the Grosvenor are palpable whereas Dana betrays only a sailorly concern about the weather.