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.
1852 - The Lighthouse Board was created to oversee all of the lighthouses in the United States. 1854 - First lighthouse on the Pacific coast was completed on Alcatraz Island in San Francisco Bay. 1860 - The first stone lighthouse built in the ocean in the United States is completed at Minot's Ledge, MA. Construction started in 1855 and it took five years to complete. It was one of the great engineering building accomplishments of its time.