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What exactly is a Chronometer?

Long standing collectors and purchasers of antique pocket watches and vintage wristwatches will of course be well acquainted with the following information, but for those new to the field it is well worth knowing.

I am asked the meaning of the term Chronometer on many occasions and it is most important for prospective collectors to understand the importance of this term.

First and foremost I would heartily recommend you read "LONGITUDE" by Dava Sobel, published byFourth Estate London. After enjoying what is not just essential reading for anyone at all interested in horology, but a great story well told. All your questions will be answered in full and you will have a much better understanding of the importance of the subject and hopefully a deeper feeling of appreciation for the fine workmanship and high grade engineering that is required to produce such items.

John Harrison's number four.C.1759

In short, a Chronometer is a highly accurate watch, it was originally used in conjunction with a sextant for establishing ones exact position on land or sea.

The execution of precise navigation being a matter of life or death and that the watches in the main were destined for the worlds Navy's, it is no wonder that these tests were extremely rigorous and demanding.

The tests consisted of observing the time keeping of the watch in various positions and at various temperatures and awarding points for accuracy in these differing states.

If the watch being tested achieved a certain level of points it would be granted the status of Chronometer and awarded a Chronometer Certificate.

Various testing laboratories around the world were responsible for grading and testing watches.The most stringent being the Kew Observatory. In most cases a Swiss chronometer test would last 15 days however, the Kew lasted 44 days.

These positions would be repeated for extreme heat and cold.

In an age before the Quartz movement Chronometer status was the highest level a watch movement could achieve and was the universal standard to set all watches against.

For this reason the great Swiss watchmaking factories set about making wristwatches that could pass Chronometer testing and gain the coveted Chronometer certificate, not that they would be used for navigation at sea but as proof positive that their product was indisputably of the highest quality.

Amongst these famous Swiss firms using Chronometer testing to promote their watches, Rolex & Omega recognized the importance of this and started very early on in the century,sending various movements to the observatories. The most successful example being the "Prince" models, each one when sold, was supplied with a Chronometer Rating Certificate.