Until recently it was thought that Nicholas Rieussec, now a model line from Montblanc, invented the proto-chronograph in the early 1820s. This was simply a machine with the ability to measure an interval of time from an arbitrary starting point. This was a crude thing with a dial which rotated under an inked nib, which could be dropped to make a small dot on command. In the last few months that invention has been superceeded by a much more "modern" chronograph, still more of a stopwatch, invented by Louis Moinet(see previous) in 1815. The machine was named the compteur de tierces, that is the counter of thirds - an archaic term for 1/60ths of a second, and includes all of the things we would expect in a modern stopwatch, including the ability to start, stop and reset the hands, a feature previously thought to have been invented in 1862 by Adolphe Nicole.
Described in Moinet's Traité Général d'Horlogerie, this watch is made the more impressive by its high frequency oscillating balance, 30hz, fast enough to make the tierce measurements pretty accurate. The movement was made in England, betrayed by the case hallmarks and the fusee, but also has some Franco-Swiss design elements, including the dial and the ruby-cylander mounted under a small, undecorated cock(yes, yes, yes...but the description is accurate).