often confused with the term chronometer. Where "Chronograph" refers to the function of a watch, chronometer is a measure of how well a given mechanical timepiece performs: in order to be labeled a chronometer the timepiece must be certified by the COSC, the official Swiss Chronometer testing institute, after undergoing a series of rigorous tests for robustness, accuracy and precision under adverse conditions (though these requirements fall far short of the accuracy achieved by even the cheapest modern quartz watch). A simple mechanical watch, without the stopwatch functionality, can be certified a chronometer, as can a clock, for example a ship's clock be used for navigation. The terms are not mutually exclusive either, for instance the Omega Seamaster 300M Chronograph GMT Co-Axial is also a COSC certified chronometer Originally the term chronograph was mainly used in connection with artillery and the velocity of missiles. The Chronograph's main function is to allow a comparison of observation between a time base and, before the electronic stopwatch was invented, a permanent recording of the observer's findings. For example, one of the first applications of the chronograph was to record the time elapsed during horse races. Some more important uses of the chronograph include the Langley Chronograph, which is used by the US Navy to record, calculate, and analyse data given off by aeroplane launching catapults. Another famous usage of the chronograph was during all of NASA's Apollo missions to the moon, each astronaut was equipped with a fully functioning chronograph, the Omega Speedmaster. Chronographs are routinely used to record heart beats within hospitals, calculate speed and/or distance on athletic fields, or even as simple timers in kitchen. Function Chronographs can be extremely complicated devices, but they all have the basic function of telling time, as they are watches, and of displaying elapsed time. Rieussec's chronograph was fairly simple. It was composed of two faces, a top and bottom face. The bottom face held a pool of ink, while the upper had a pen-like needle attached to it. When activated, the upper face pushed down on the lower face, while revolving around a central axis, which pulled the needle. This dragged the ink, in a circular fashion, recording the time elapsed by the line of ink that the motion created. There was room left for improvement, because Rieussec's chronograph was not easily ready for multiple uses. This paved the way for the hundreds of