I has always thought that a chronometer was a watch that had several functions, I was reading the Rolex booklet that came with my Submariner and it states " A chronometer is a watch that has been severely tested for 15 days and nights, in 5 different positions and at three temperatures by the Controle Officiel Suisse des Chronometres" onced the movement has successfully pased this it can bear the word chronometer on the dial. So I guess all our railroad watches are Chronometers, I had never read this booklet before and I have had it since 1988.

Hi Jeff, I think you may have confused chronometer with chronograph. The chronograph's have the extra functions you are thinking of.

Hi Jeff, a chronometer is a watch that is adjusted to operate in different positions and keep time in each position within a specified gain/loss over a specified time frame. A Chronograph is a watch with the added feature of a stop watch. The watch itself could also be a chronometer. hope this helps

Railroad timekeeping is also different from chronometer time keeping. A railroad watch could be plus or minus X seconds over a period of time. This assures accurate timekeeping. A chronometer as previously stated must have a specified rate of gain or loss over a 1 day period of time in several positions. In this case the rate of change is what is being controlled, not absolute timekeeping ability. The reason for this was use on ships and navigation. If you knew the rate of change on your timepiece on a daily basis, you could accurately measure either longitude or latitude (I don't remember which). So, in fact, railroad timekeeping is actually more interested in absolute rather than relative timekeeping and a chronometer is the opposite. Both useful for their purpose.

You guys are right the word "Chonograph" never entered my mind, these are the ones with the extra dials and functions, I had a senior moment. Thanks Jeff