Telescopes from the Ground Up

Era of Great Refractors

Yerkes 40-inch Refractor

The refracting telescope takes its final bow

In 1895, workers finished the largest achromatic refractor that would ever be created: the Yerkes telescope. George Ellery Hale, an American astronomer, convinced the Chicago tycoon Charles Tyson Yerkes to finance the telescope. Yerkes was a convicted embezzler with a reputation for dishonest deals, but he liked the idea of his name being attached to a famous telescope. He said he would pay whatever it took, but insisted repeatedly that the telescope had to be the largest in the world.

The telescope was built at Lake Geneva, Wis., near Chicago, 240 feet (73 meters) above sea level. This location was considered low, now that telescopes were being built on mountaintops to avoid some of the distorting effects of the Earth’s atmosphere. But the temperatures in the area could reach –20 degrees Fahrenheit in the winter, cold enough for the skies to be quite clear. Hale also felt mountaintop observatories were prone to storms, which could limit viewing.

• Harvard Refractor1847
• Naval Observatory1873
• Yerkes Refractor 1895

• Home
• Basic Science Concepts
• Copyright
• Site Map