Yerkes Observatory: Pioneer of the 40-inch Refractor Era

The Yerkes Observatory, located at West Geneva St 373, Williams Bay, Wisconsin, United States, originated in 1892, the brainchild of astronomer George Ellery Hale and businessman Charles T. Yerkes. It signified a significant shift in the understanding of observatories as mere telescope and observer dwellings, evolving into the 20th-century perception of observation equipment integrated with lab space for physics and chemistry.

The observatory houses a 40-inch aperture refracting telescope, the largest of its kind in the 19th century. Crafted by Alvan Clark & Sons, this historical item served as a hub for serious astronomical research for over 100 years. Although it reached the end of its research life by the 21st century, the University of Chicago kept ownership until November 2019, passing the baton to the non-profit Yerkes Future Foundation (YFF). The observatory re-opened for public tours and programming in May 2022.

Sources: Wikipedia, OpenStreetMap, Wikidata, Wikimedia Commons