local geologic forms, resumed when he taught at the University of Cincinnati. Clarke returned to Boston after the AY 1868-1869, and resumed lectures at the Boston Dental College and pursued literary and journalistic endeavors, including reporting for the Boston Advertiser, through 1873. Public Service Clarke retired from the public service on January 1, 1925, having served as the Chief Chemist of the U.S. Geological Survey since 1883. Part of his Survey work included analysis of the Yellowstone geysers and their water. He also supported American contributions to many exhibitions, most notably the 1900 Paris Exposition. At the centennial of John Dalton's atomic theory held at Manchester, England in 1903, Clarke delivered the Wilde Lecture. Returning to England in 1909, he presented before The Chemical Society on the subject of his mentor, Wolcott Gibbs. His forty-two year career included parallel service with the United States National Museum as 'honorary curator' of minerals. The Smithsonian Institution's extensive mineral collection "are due in large measure to his active interest and his painstaking efforts both in the collection and exhibition of specimens." From 1892 to 1902, Clarke was the lone member of the American Chemical Society's Committee on Atomic Weights. In 1902, the need for commonality between active American and German scientific committees prompted the formation of the International Commission on Atomic Weights, with Frank Clarke as its chairman. As chairman, Clarke guided the international committee in successive revisions of the Periodic Table of Elements which continued until interrupted by the First World War in 1918. Academic career Prior to entering the federal service, Clarke taught chemistry and geochemistry at Howard University (1873–1874) and the University of Cincinnati (1874–1883). In 1874, Frank W. Clarke became spouse to Mary P. Olmstead of Cambridge, Massachusetts. While at Cincinnati, he made extensive forays into Appalachia to study its geology and form. Clarkes' first academic work was entitled On a new process in mineral analysis (March 1868). It was published at age 20 and during the year he went on to serve as an instructor in Chemistry at the new Cornell University. Even after he left academia, his bookish qualities were well known. He would time his Cosmos Club library visits to coincide with the librarians' opening of the periodical mail and was keen on being the first to know, rather than the one to receive, the news. Personality, including humor Clarke was not a hearty laugher. He