m akers ▁looked ▁to ▁a ▁ph al an x ▁of ▁astronom ical ▁observ ator ies ▁located ▁in ▁Western ▁Europe ▁to ▁conduct ▁assess ments ▁of ▁time pie ces . ▁The ▁observ atory ▁staff , ▁applying ▁a ▁sl ate ▁of ▁accuracy ▁tests , ▁would ▁either ▁reject ▁a ▁time pie ce ▁as ▁in ac cur ate , ▁or , ▁if ▁it ▁passed ▁the ▁string ent ▁testing , ▁would ▁cert ify ▁it ▁ ▁as ▁an ▁observ atory ▁chron ometer . ▁Thus ▁the ▁" observ atory ▁trial " ▁was ▁developed ▁as ▁the ▁standard ▁process ▁for ▁determ ining ▁accuracy ▁of ▁time pie ce ▁movements . ▁ ▁Once ▁mechanical ▁time pie ce ▁movements ▁developed ▁sufficient ▁precision ▁to ▁allow ▁for ▁accurate ▁marine ▁navigation , ▁there ▁eventually ▁developed ▁what ▁became ▁known ▁as ▁" chron ometer ▁compet itions " ▁at ▁the ▁astronom ical ▁observ ator ies ▁located ▁in ▁western ▁Europe . ▁The ▁Ne uch atel ▁Observ atory , ▁Gene va ▁Observ atory , ▁Bes an con ▁Observ atory , ▁and ▁K ew ▁Observ atory ▁are ▁prominent ▁examples ▁of ▁observ ator ies ▁that ▁cert ified ▁the ▁accuracy ▁of ▁mechanical ▁time pie ces . ▁The ▁observ atory ▁testing ▁regime ▁typically ▁last ed ▁for ▁ 3 0 ▁to ▁ 5 0 ▁days ▁and ▁contained ▁accuracy ▁standards ▁that ▁were ▁far ▁more ▁string ent ▁and ▁difficult ▁than ▁modern ▁standards ▁such ▁as ▁those ▁set ▁by ▁C OS C . ▁When ▁a ▁movement ▁passed ▁the ▁observ atory , ▁it ▁became ▁cert ified ▁as ▁an ▁observ atory ▁chron ometer ▁and ▁received ▁a ▁Bul letin ▁de ▁Mar che ▁from ▁the ▁observ atory