Yerkes Observatory, Williams Bay, Wisconsin, USA, 1915

Yerkes Observatory, Williams Bay, Wisconsin, USA, 1915. Photograph of the domes and buildings of the Yerkes Observatory at Williams Bay, Wisconsin in the United States. Its primary instrument is a 40 inch refracting telescope built by the American company of Warner & Swasey Ltd with optics by Alvan Clark & Sons that was completed in 1897. Established as part of the University of Chicago, the observatory was the brainchild of its first director, George Ellery Hale (1868-1938). He managed to convince Charles Tyson Yerkes (1837-1905), a Chicago railway tycoon, to fund the whole project. Today it is still the largest refracting telescope in the world. ©SSPL/Science Museum