Foghorn

Pneumatic foghorn, painted black, with the inside of the bell red. On the outer pipe, the bell is positioned at a 90-degree angle as in a ventilation shaft. The pipe has two handles. The air chamber is formed by the outer pipe slid over a separate inner pipe, which is closed at the bottom; air pressure is obtained by pushing both pipes together, while when they are pulled apart, air is admitted into the chamber through a valve in the bottom of the inner pipe. The tone is produced by a reed on a long conical inner pipe, which is mounted inside the chamber on the outer pipe. The horn is operated by moving the outer pipe up and down with both hands, while the inner pipe is held in place at the bottom with one foot in a foot stirrup.