On 7 September 1875, Helena Blavatsky, William Quan Judge, Henry Steele Olcott, and others founded the Theosophical Society in 
New York (click for geospatial location) following an inspiring lecture by J. G. Felt. Olcott was the first President. Image: Photograph of Henry Steel Olcott. This image is in the public domain in the United States because its copyright has expired.
Articles
Dennis, Denisoff, “The Hermetic Order of the Golden Dawn, 1888-1901″
