Foghorn memorial day

On this day, December 20th, in 1879, Japan's first foghorn was installed at Shiriyazaki lighthouse, located on the east coast of Honshu in the Tsugaru Strait, Higashidori in Aomori Prefecture. It is a registered Tangible Cultural Property of Japan. 

The lighthouse was built in 1873 and in 1901 it became Japan's first electrical lighthouse. When they installed the foghorn in 1879, it sounded for four seconds every 20 seconds. That was to ensure safe navigation in fog.

Of course, foghorns are just used in lighthouses, but on ships too. And they aren't just used in fog, but when there is low visibility to warn of any navagational  hazard such as two ships or land too close.