The Philosophical Society of Washington is the oldest scientific society in Washington, D.C.

Washington, D.C.

Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....

 It was founded in 1871 by Joseph Henry

Joseph Henry

Joseph Henry was an American scientist who served as the first Secretary of the Smithsonian Institution, as well as a founding member of the National Institute for the Promotion of Science, a precursor of the Smithsonian Institution. During his lifetime, he was highly regarded...

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Its aims are "the promotion of science, the advancement of learning, and the free exchange of views among its members on scientific subjects."

Since 1887, the regular meeting place has been the assembly hall of the Cosmos Club

Cosmos Club

The Cosmos Club is a private social club in Washington, D.C., founded by John Wesley Powell in 1878. In addition to Powell, original members included Clarence Edward Dutton, Henry Smith Pritchett, William Harkness, and John Shaw Billings. Among its stated goals is "The advancement of its members in...

, now called the John Wesley Powell

John Wesley Powell

John Wesley Powell was a U.S. soldier, geologist, explorer of the American West, and director of major scientific and cultural institutions...

auditorium.

Meetings are usually held every other Friday, except in the summer. Meetings are free and open to the public. A lecture is given by a scientist at each meeting.