Science News, the weekly news magazine of science has a cool timeline feature with stories from the past. They just posted some information dating from 70 years ago this week.
In their January 29, 1938 issue. they reported that "The dome for the great 200-inch telescope on Mt. Palomar is practically finished structurally, and California Institute of Technology engineers can now breathe easier while completion and installation of equipment take place under its shelter during the next couple of years. By February 1, the dome itself will be complete."