This is Old Baldy Lighthouse's oil house. Constructed in 1905, the oil house safely and properly stored containers of kerosene that fueled Old Baldy's lantern during the late nineteenth century and early twentieth century.
Before kerosene, whale oil fueled Old Baldy's lantern. Whale oil comes from the blubber, or fat, of spermaceti whales. Hunting whales to produce whale oil was a major industry during the nineteenth century in America. Due to over-hunting, whales became increasingly harder to hunt, which increased the cost of whale oil. After the civil war, the U.S. Lighthouse Service sought a cheaper fuel for the nation's lighthouses. After experimenting with colza oil, lard, and other fuels, the U.S. Lighthouse Service settled upon kerosene, known as mineral oil.
Kerosene is highly combustible, so the lighthouse service constructed brick, insulated oil houses to properly store kerosene at lighthouses. These oil houses protected the kerosene from exploding due to fire. Old Baldy's oil house was completed in 1905 and used until Old Baldy was decommissioned in 1935. Today, Old Baldy features a purely decorative, electric light.