In the 19th century when Nobel invented dynamite, portable clocks were not yet very convenient and bells used to tell the hour. In Europe, bells in Churches told the hour. And in Japan, bells in temples told the hour.
But the improvement of the gunpowder performance gradually changed the tradition. In Japan, The government decided to fire the cannon at noon everyday at the Edo Castle in 1871. Even today, some countries such as Hong Kong and South Africa continue to fire the noonday gun.
"Cannon" was engraved on the name of Alfred Nobel when he was born.