Observatories and Instruments

Albert Einstein and the observatory staff in front of the 40-inch Refractor, 1921. Photo courtesy Yerkes Observatory.

I like to check into Yerkes Observatory in Williams Bay, Wisconsin, every once in awhile, just to make sure it’s still standing.  The observatory, which houses multiple instruments (a 102 cm [40 inch] refracting telescope, a 102 cm reflecting telescope, and a 61 cm [24 inch] reflecting telescope, and several small telescopes), is one of several founded by the incredibly energetic astronomer, George Ellery Hale (dates).  Although conditions at this observatory are not ideal for observing—they perhaps never were, as Hale eventually left Wisconsin for California in search of skies with less atmospheric turbulence—the observatory still functions as a research space for the University of Chicago.

The 40-inch refractor at Yerkes is still the largest of its kind in the world (the 49-inch refractor exhibited at the Great Paris Exhibition of 1900 was dismantled afterward).  The mirror for the scope was ground by Alvan Clark & Sons from a 42-inch blank that Hale heard about “by chance.”  Some chance!  The scope’s tube, mounting, dome, and rising floor were designed by the firm of Warner & Swasey, out of Cleveland, Ohio.  Hale had been working in his private observatory (Kenwood Observatory), but after some back-and-forth with the president of University of Chicago, secured an associate professorship and the promise of new observatory in which he could install the great refractor.  The money to build the observatory came from the pockets of Chicagoan Charles Yerkes, who allegedly was enamored with the project simply because he wanted to build “the biggest” of some interesting thing.  The scope was in place by 1897, and astronomers instantly put the refractor to good use.  For instance, Burnham’s Catalogue of Double Stars was finished at Yerkes, as was Barnard’s Photographic Atlas of Selected Regions of the Milky Way.  A great many of astrophotographic  techniques were pioneered at Yerkes, as well.

One of the strengths of the Yerkes Observatory is the condition of its telescopes, despite their age.  Because of the good state of preservation of the observatory and its continuing relationship with academic institutions, visitors not only have an opportunity to learn about the history of observational astronomy, they can see how observatory and its instruments  contributed to the professionalization of astronomy.  Yerkes runs programs for students of all ages (including the visually impaired!), putting young people in contact with both historical and contemporary approaches to research and development at the observatory.

The R&D program occasionally makes use of the historic instruments at the observatory.  For instance, a project to measure stellar motion takes advantage of photographs taken in the early 1900s and the 1980s with the 40-inch refractor.  Yerkes has over 170,000 photographic plates for use by researchers.

In truth, however, the observatory is mostly important because of its history, not because R&D relies on the original telescopes (University of Chicago does most of its observational astronomy at the Apache Point Observatory in New Mexico).  Because of this, the observatory is frequently under threat by plans to sell or develop the surrounding property.  Most recently, the property was slated for development for a luxury residential complex, but in the end, an appointed study group felt the observatory had too much potential as an educational center to surrender the property to a private developer (the final report was made available to the public).

As a historian of observatories, I can only be pleased that University of Chicago has re-dedicated itself to the preservation of the property, not just because it played a large role in the development of astronomy in the United States, but because the architecture of and the landscape surrounding the building are unique in their aesthetic. Those of you who have done work at the Newberry Library in Chicago might recognize the design hand of Henry Ivy Cobb in the Yerkes Observatory buildings.

Yerkes Observatory, Williams Bay, Wisconsin

Detail of Pillar, Yerkes Observatory. Photo courtesy of Yerkes Observatory.