Mr. Büsser had invited Mr. McDonnell to dinner because he couldn’t wait to show off the vintage Tiffany chronograph pocket watch that he had just bought. “I was so proud of it,” he recalled recently.
But Mr. McDonnell was not impressed: “I could just see all its technical faults.”
“Its precision is rubbish; all chronographs have inherent technical flaws and functionality,” he remembered telling Mr. Büsser. “As soon as you turn on the chronograph, it sucks away about 30 percent of the watch’s energy and eats away at the timekeeping ability and the stopwatch function.”
Mr. Büsser asked if he had a better idea.
“Maybe,” Mr. McDonnell replied.
“Then let’s do it,” challenged Mr. Büsser.
A chronograph is a stopwatch that can measure the passage of time during, for example, a sports competition or a chess game. The invention is attributed to Louis Moinet, a French horologist, who in 1816 created what he called a compteur de tierces (in English, counter of thirds) to time the passage of stars, planets and planetary moons. The first commercial application was created in the early 1820s, when King Louis XVIII of France commissioned one of his royal watchmakers, Nicolas Mathieu Rieussec, to develop a watch that could be used to time his racehorses.
“With a conventional chronograph, all you can do is stop, start and return to zero,” Mr. McDonnell said. “You can’t time multiple things. You can’t time multiple events that all begin at the same time. You can’t time individual laps.” His reinvented chronograph does all of those things, in part because it has two chronographs, alongside its traditional timekeeping function.
“Because there are two independent chronographs,” said Mr. Büsser, 56, “you can time two different things at once — for example, the eggs and the pasta, racecars doing laps.”