Hale telescope
Saint-Gobain cast the glass blanks of some of the largest optical reflecting telescopes of the early 20th century, including the ground-breaking Hale telescope (online in 1908) and 100 inch (2.5 m) Hooker telescope (online 1917) at Mount Wilson Observatory (USA), and the Plaskett telescope (online in 1918) at Dominion Astrophysical Observatory (Canada).