What J. B. Dunlop invented?

From early modern times until the present, Russia (temporarily extended to the USSR) had two capital cities: Moscow and Petersburg. Moscow was the original capital, it was succeeded by Petersburg from the beginning of the 18th century. For several centuries until 1712 Moscow was the capital of the Russian state. When the capital was officially transferred to St.-Petersburg. On March 12, 1918, Moscow became the capital once more but now it was the capital of the Soviet state.