Alex Demas (Former Employee)

Hiking trails on Theodore Roosevelt Island, in Washington, DC.

A statue of Theodore Roosevelt on Theodore Roosevelt Island.

A statue of Theodore Roosevelt on Theodore Roosevelt Island.

A statue of Theodore Roosevelt on Theodore Roosevelt Island.

A panorama of the Potomac River at Rosslyn, Virginia. On the right can be seen the Theodore Roosevelt Island of Washington, DC. On the left are the office buildings in Rosslyn.

A view of Rosslyn, VA, and the Potomac River from Theodore Roosevelt Island in Washington, DC.

A view of Rosslyn, VA, from the footbridge that connects Theodore Roosevelt Island to the Commonwealth of Virginia.

Petroleum was refined onsite to differing levels depending on what its purpose was. Differing petroleums were stored in wells like these for ease of access.

Petroleum was refined onsite to differing levels depending on what its purpose was. Differing petroleums were stored in wells like these for ease of access.

Petroleum first saw widespread use in the transporation industry as a lubricant. It was refined into various products depending on which part of the engine they were meant to lubricate. Once transported by tanker car, it was stored in large tanks such as this one.

Petroleum first saw widespread use in the transporation industry as a lubricant. It was refined into various products depending on which part of the engine they were meant to lubricate. It was transported in tanker cars like this one.

A sand storage silo at Steamtown National Historic Site. Sand was stored in a dome on top of the engine and, as the train traveled the tracks, the sand would be sprinkled down pipes to land on the tracks in front of the wheels. This would aid the wheels in gripping the tracks, especially when the rails were wet.

Railroad tracks at Steamtown National Historic Site. Originally, rails were made of iron, but as steel production became more efficient, steel replaced it and is still used today.

A steam engine at the Steamtown National Historic Site. Steam engines demonstrated one of the first comprehensive intersections of energy, mineral, and water resources. Steam engines required coal for fuel to boil water to make steam, as well as iron and steel for the casings and sand for traction on the rails.

Railroad tracks at Steamtown National Historic Site. Originally, rails were made of iron, but as steel production became more efficient, steel replaced it and is still used today.

A sand storage silo at Steamtown National Historic Site. Sand was stored in a dome on top of the engine and, as the train traveled the tracks, the sand would be sprinkled down pipes to land on the tracks in front of the wheels. This would aid the wheels in gripping the tracks, especially when the rails were wet.

A locomotive turntable. These were used to move trains from track to track.

Coal was essential to the operation of the larger steam engines. Coal burns at extremely hot temperatures and burns for a long time, making it an ideal fuel for converting water into steam.

Steam engines used high-grade silica sand for traction on the rails. Sand was stored in a dome on top of the engine and, as the train traveled the tracks, the sand would be sprinkled down pipes to land on the tracks in front of the wheels. This would aid the wheels in gripping the tracks, especially when the rails were wet.

Steam engines used high-grade silica sand for traction on the rails. Sand was stored in a dome on top of the engine and, as the train traveled the tracks, the sand would be sprinkled down pipes to land on the tracks in front of the wheels. This would aid the wheels in gripping the tracks, especially when the rails were wet.

A meadow on Lower Culp's Hill, one of the battle sites at Gettysburg Battlefield.