A watch or clock for which that individual item has been tested by the SSC and had a CSSC certificate issued.

The story behind the invention of the Chronometer is an interesting one.

When humanity's fascination with the sea first began many thousands of years ago, we had one major difficulty: if we lost sight of the shore, we were in major trouble. Because we had no means of calculating our location in regards to our origin or destination, we had no real means of navigating except by following the shoreline until we reached something interesting.

With the invention of the sextant, humanity had finally solved half the puzzle. We were able to find our latitude by using the stars as our guide.

But although we had the ability to calculate how far North or South we were, we still had no means of figuring out our longitude, our East/West coordinates. This is why Christopher Columbus thought he was in India -- he had no way of knowing whether he had reached the Far East or not (the Carribean ended up being the named Near East thanks to his screw-up).

Eventually, scientists and navigators figured out that if you know what time it is where you are, and the time in another location, then you can figure out your longitude via some simple subtraction.

Sadly, wristwatches (or even pocketwatches) had not been invented in the 1700's, and the time-keeping devices of the period served better as decorative pieces than reliable timepieces (and, indeed, accuracy was necessary in order to calculate longitude).

And so, in 1714, the British Board of Longitude began a contest. The prize: 20,000 pounds (i.e. millions and millions and millions of dollars by today's inflated standards) to whomever could devise a method to calculate longitude.

A young man by the name of John Harrison dedicated much of his life to finding a solution to this problem, and in 1735 presented his first design to the Board, followed by several more until it was perfected in 1759.

Sadly, although Harrison was the only one to come close to creating an accurate timepiece, the Board decided to give the prize to an astronomer, Nevil Maskelyne, who had devised a rediculously complicated way of calculating longitude involving the moon and several specific stars.

Eventually, at the age of 80, Harrison was given the full award by King George III, but died three years later

It is interesting to note that while Maskelyne was declared the winner, Harrison's method is still in use today, and has only recently begun to be replaced by GPS.

Chro*nom"e*ter (?), n. [Gr. time + -meter: cf. F. chronometre.]

1.

An instrument for measuring time; a timekeeper.

2.

A portable timekeeper, with a heavy compensation balance, and usually beating half seconds; -- intended to keep time with great accuracy for use an astronomical observations, in determining longitude, etc.

3. Mus.

A metronome.

Box chronometer. See under Box. -- Pocket chronometer, a chronometer in the form of a large watch. -- To rate a chronometer. See Rate, v. t.