This week's Palomar Observatory History Photo of the Week is a few days late, so to help make up for that I present two photos from the Caltech optical shop.
Both photos come from the collection of pictures donated by optician Blake Mitchell.
Here is Blake's description for the top photo:
"Bob, Mel & Blake, the living tool-pressing weights."
He gives a more detailed description for the second photo:
"Standing was tiring so we sat down for 30 minutes to press the 68-inch polishing tool into perfect contact with the 200-inch mirror."
From left to right in both pictures is Bob (Robert) George Smith, Melvin Johnson and Blake Mitchell.
Note that the center plug is in place in these photos. The center plug was used during the grinding and polishing work on the mirror and is now on display at Griffith Observatory.
I don't have firm date on the photos, but I believe that they were taken sometime after work on the 200-inch mirror resumed after the conclusion of World War II.