Skip to main content
It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.
The 200" Disk for the Hale Telescope
This guide provides historical, digital, and archival resources on the pouring of the 200" disk which was used in the Hale Telescope at Palomar Mountain in California. When the disk was cast, it was the largest single piece of glass ever made.
The mirror was made using Corning Glass Works' signature Pyrex®, a special glass designed to resist heat expansion. After many years of trial and error experimentation, as well as the advent of World War II, the disk was finally installed in 1948 in the Palomar Observatory.
This LibGuide is a selective list of resources on the topic. For more information, please search our library catalog or contact a reference librarian through our Ask a Librarian service.
Find Answers to Your Glass Questions
The Pouring of the 200" disk
Rakow Research Library Hours
Open by appointment only
Phone and Appointment Hours:
Chat with a Librarian:
10:00am-12:00pm and 2pm-4pm
Hours vary. To see list of available appointment times, visit reserve.cmog.org.