Telescopes
Yerkes Observatory is most famous for its 102 cm (40 inch) refracting telescope built by the master optician Alvan Clark. This is the largest refracting telescope used for scientific research (a larger demonstration refractor, the Great Paris Exhibition Telescope of 1900, was exhibited at the Paris Universal Exhibition of 1900). The 40-inch telescope was exhibited at the 1893 World's Columbian Exposition in Chicago before being installed in the observatory.
In addition to the Yerkes refractor, the observatory also houses 102 cm (40 inch, referred to as the "41 inch" to prevent confusion) and 61 cm (24 inch) reflecting telescopes. Several smaller telescopes are used for educational outreach purposes.
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