Explore Further: The 100-Inch Hooker Telescope

The instrument's name honors John D. Hooker, a businessman who donated funds to make the mirror. The telescope was a mechanical masterpiece, and its mirror, 2.5 meters (100 inches) in diameter, remains the largest solid plate glass mirror ever made.

The giant telescopes on Mount Wilson were made possible by the introduction of glass mirrors. A method for depositing an extremely thin, even coating of silver on glass was developed in the mid-19th century. Glass mirrors had many advantages over the metal mirrors used by William Herschel and others. They held a higher polish and could be stripped and recoated quickly when they tarnished, without having to be repolished.

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