He refined Foucault's approaches in 1926 using improved rotating mirrors to measure the time it took mild to generate a round excursion from Mount Wilson to Mount San Antonio in California. The precise measurements yielded a pace of 299796000 m/s.[eighteen]???? ?????? ?? ???? ????? ? ????? ??? ?? ??? ???? ?????? ??? ????? ? ?? ??? ??? ??? help sav