If you'd like to visit this bell tower, you don't have to travel far in the state of Maine to visit it. It is only one of a few remaining bell towers in America and it resides along the Penobscot River in Stockton Springs, Maine.

Gary Freeman, Townsquare Media

The bell was struck every 20 seconds, which seems like a lot. The bell was cast by Blake Company of Boston, Mass. in 1890. In 1958, the Stevens Apparatus was replaced with a hammer that was activated by an electric motor and cam device.

Gary Freeman, Townsquare Media

You can see how the system worked in the photo diagram below.

Gary Freeman, Townsquare Media

In the 1960's, the fog bell signal was replaced by an electric diaphragm horn and was located on the outside of the light tower and was later relocated below the tower on the cliff.

Gary Freeman, Townsquare Media

The keepers of the bell tower needed only to turn on a switch when it became foggy and by the 1980's, an automatic fog detector called a Video Graph B was installed and took the place of the old mechanism.

Gary Freeman, Townsquare Media

The Video Graph B is made up of two principal parts - the projector and receiver.

This mechanical keeper, of sorts, is always sending out strobe-type flashes of light to the atmosphere from its projector.

The way it works is when the light hits these particles it retracts in many directions to include going back to the fog detector where the receiver monitors what is called back scattered light, or backscatter as many call it today.

The Video Graph B was located inside the tower work room and was the technology needed to automate lighthouses and, eventually, eliminated the need for a lighthouse keeper.

Gary Freeman, Townsquare Media, Fort Point Lighthouse, ME

Recently, the Video Graph B has been replaced by a VH-100 fog detector which is mounted on the outside of the tower and is maintained by the US Coast Guard Aids to Navigation Team or ANT.

The Fog Bell Tower is listed on the National Historic Register and is the property of the Maine Bureau of Parks and Lands.

The video below will give you an idea of what the whole tower looks like and how the electric operated hammer works, as it rests on the shore of Fort Point and looks out upon the Penobscot River in Maine.