On this day in history, August 10, 1846... President James K. Polk signed the legislation that established the Smithsonian Institution as a "trust instrumentality" of the United States. In other words, the Smithsonian was established by the U.S. government as a public trust. The British chemist and mineralogist James Smithson left most of his wealth when he died in 1829 to his nephew, Henry James Hungerford. Smithson was childless and his nephew was childless, also, so according to Smithson's will, the estate passed "to the United States of America, to found at Washington, under the name of the Smithsonian Institution, an Establishment for the increase and diffusion of knowledge among men." As a public trust, the thirty million visitors are admitted without charge each year. Refered to by some as "the nation's attic," the Smithsonian Institution includes nineteen museums, nine research centers, and zoo and its museums include a total of 154 million items.