In order to make it easier to describe elements and molecules, chemical formulas are used. For example, H represents one atom of hydrogen and O represents one atom of oxygen. If we want to represent two atoms of hydrogen, instead of writing H H, we write H2.
This car is named for Promontory Summit, Utah, just north of Great Salt Lake and the site selected for the joining of the Union Pacific and Central Pacific Railroads. Completion of the railroadâthe greatest engineering feat of the 19th centuryâculminated in a celebration there on May 10, 1869. Promontory Point, often erroneously referred to as the location for the ceremony, juts out into the lake itself. It was the location of a saltworks for many years.
The Tillamook Rock Lighthouse was built in the 1880s. Dangerous and expensive to operate, it was decommissioned in 1957. Credit Stuart Isett for The New York Times . CANNON BEACH, Ore. â Tillamook Rock Lighthouse, a mile off the Oregon coast and dark for half a century, would be just another postcard from the past if not for all the dead people inside.