Fog Alarm building was constructed in 1885. It was a one story structure with a T-shaped plan. Foghorns sprouted from the hipped roof of the “leg” of the T. The foghorns were diaphones invented in Canada which produced a loud “blast” followed by a “grunt”. It used compressed air generated by a steam, gas, or oil engine housed in the same building. The foghorn operated on 30lbs of compressed air per blast.