[citation needed] Delettrez worked alongside Achille Brocot for several years and their clock movements are considered to be the most effective made during the late 19th century.
Their specialty was a range of clocks based on the innovations of Brocot père and his other son Antoine, but generally of Achille's greatly advanced original design, some having a unique single-arm double-wheel escapement, some having a temperature-compensated pendulum, some having two dials, one of which showed the time and the other which showed a calendar and often other information such as phases of the moon, times of sunrise & sunset in Paris, etc.
[1][2] The firm was awarded a 1st class prize at the Paris World Exposition of 1857 for a commercial clock of this type.
His typical later product was a conventional 8-day mantle clock that struck the hours and half-hours, still based on the standard Brocot escapement and suspension that he had helped to refine.
They had two sons, Louis and Jules, both of whom later carried on the family tradition of metalworking, the former as a manufacturer of bronze objets d'art and the latter as a goldsmith.