 Pierre Le Roy's chronometer had a performance equivalent to that of the Harrison H4 chronometer.In 1769, after his chronometre underwent testing aboard the corvette "Aurore", he was awarded the double prize offered by the Académie française for the best method of measuring time at sea.He succeeded in giving his instruments the greatest possible regularity by the discovery of the isochronous spiral spring, in which he was in competition with Ferdinand Berthoud, but which he published first.