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Hi!

I just read the "Longitude" book by Dava Sobel. Consider this WI involving clockmaker John Harrison.

Instead of rushing H-4 (the prize-winning watch) onto the ship for the longitude test at the last minute (he had originally planned on using H-3, a larger machine, for the test but a war had gotten in the way and held everything up if I remember correctly), he decides to test H-3.

The ship, as in OTL, encounters stormy seas. In OTL, Harrison's son has to tuck H-4 under his shirt to prevent it from getting wet and breaking down. He can't do this, however, with H-3. The combination of storms and water damage cause H-3 to break down midway through the voyage.

The Board of Longitude, having been skeptical of a mechanical solution to the longitude problem to begin with, gets tired of the stubborn clockmaker. They stonewall on the test of H-4 long enough for Nevil Maskelyne, an astronomer, to perfect longitude using the lunar distance method (in OTL, lunar distance was used to calibrate chronometers for a long time as a backup -- this is what earned Maskelyne's observatory at Greenwich the right to become the prime meridian). Harrison dies in 1776 a broken man.

By 1800 the lunar distance method becomes the primary means of determining longitude. The key here is that this method can be used by any country on the planet as long as someone has a copy of Maskelyne's tables (or creates their own). Suddenly, all European countries are on the same footing when it comes to exploration. What happens next?

The marine chronometer is eventually invented 100 years later or so when the trip across the ocean becomes smoother with new technology. At that point, however, it becomes more of a curiosity. Besides, we're 100 years after the POD and the lunar distance method is firmly entrenched.

ACG
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