В 1736 г. академик Делиль предложил отмечать полдень выстрелом из пушки

On December 22, 1735, the astronomer and mathematician Joseph Delille, invited to Russia by Peter I himself, spoke at a meeting of the St. Petersburg Academy of Sciences. The respected scientist proposed “to give every St. Petersburg resident a way to wind up a wall or pocket watch correctly.” Delille's method was simple. At a signal from the Kunstkamera tower, where an astronomical observatory with correct meridians and a true clock was situated at the time, a cannon at the Admiralty fired. But no, the cannon did not fire in 1736. The scientist's proposal was implemented only 130 years later. Even later, the cannon was moved to the Peter and Paul Fortress. At noon Moscow time, it fires from there today.