Wisconsin 101

OBJECT HISTORY: Yerkes Telescope

The 40-inch refracting telescope at Yerkes Observatory in Williams Bay, Wisconsin, contains the world’s largest refracting lenses. Built in 1895, the telescope contains two lenses, one made of crown glass, and one made of flint glass. The lenses are each 40 inches in diameter, weigh 500 pounds, and have a 62-foot focal length. The telescope and observatory…

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September 10, 2019

Williams Bay, WI

Captain Israel Williams founded Williams Bay, Wisconsin, in 1835. Williams and his two sons originally traveled to Wisconsin from their Massachusetts home to look for good farmland. Williams Bay was later named in honor of Captain Williams.Until 1890, only a few families…

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May 9, 2018

Williams Bay / Walworth County / Yerkes Telescope / Region 7 - South Center / Related Stories / Science & Medicine / 1900-1920 / 1920-1940 / 1940-1960 / Education / 1960-1980 / 1980-2000

Astronomy in the 1900s

In the 1800s, astronomers valued telescope magnification to investigate planets and stars. In the 1900s, astronomers started to ask questions about the structure of our galaxy, the Milky Way, which lead to greater emphasis on light-gathering power. By 1951, William Morgan at…

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May 9, 2018

Walworth County / Williams Bay / Yerkes Telescope / 2000-2020 / 2020-2040 / Region 7 - South Center / Related Stories / 1880-1900 / Science & Medicine / 1900-1920 / 1920-1940 / 1940-1960 / Education / 1960-1980 / 1980-2000

Yerkes Telescope Construction and Use

The construction of the 40-inch refracting telescope at Yerkes Observatory in Williams Bay, Wisconsin, was directed by George Hale, an astrophysicist at the University of Chicago, and funded by Charles Yerkes, a Chicago businessman. The telescope is made of 40-inch glass lenses manufactured by the…

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May 9, 2018