stephenb
21-06-2010, 08:32 PM
I thought I'd share some information on the 200-inch Mount Palomar mirror which has been discussed on my railway forums, in particular, its transportation by rail from the manufacturer to the observatory. Here are some images and a summary of the transportation process. The full history can be found at: http://www.astro.caltech.edu/palomar/history.html#1936
George Hale..."...secures a grant of six million dollars from the International Education Board, a funding agency endowed by the Rockefeller Foundation, for "the construction of an observatory, including a 200-inch reflecting telescope... and all other expenses incurred in making the observatory ready for use." Unlike the Mt. Wilson observatories, which are operated by the Carnegie Institution, the 200-inch is administered by the recently founded California Institute of Technology (Caltech). Hale and his teams of astronomers, engineers, and opticians set to work."
Photos 1 & 2
The blank was..."...with only a rough flat front surface, is shipped across the country on a special train from New York to Pasadena, always traveling slower than 25 miles per hour. The telescope project has captured the public imagination, and thousands of people line the train tracks to watch this special cargo. Guards are posted around the mirror during overnight stops to prevent any damage to the disk. The trip takes sixteen days."
In 1936..."...In the optics lab at Caltech, the front surface of the mirror is ground to the approximate concave form required. Using successively finer polishing grit, the opticians then carefully smooth the surface, constantly using optical tests to compare it to a perfect paraboloid shape. It is slow and painstaking work. To make the final mirror, almost 10,000 pounds of glass are polished away, including the top two inches which contain "scar tissue" left over from the casting and annealing process."
"Telescope production halts because most of the engineers and scientists, as well as their laboratories, are reassigned to war-related projects. Not even mirror polishing continues during the war. The 200-inch disk is stored and protected by timbers for three years. After the war concludes, telescope work restarts in September of 1945. After three months of cleaning the labs, mirror polishing resumes. Most of the pre-war telescope workers do not continue with the project, so a new crew must learn the routines. "
Photo 3 "The 200-inch mirror is transported from Pasadena to Palomar on November 18-19, 1947. The 40 ton cargo requires three diesel tractors to push it up the mountain. Despite a storm, which nearly aborts the transport, the 125 mile trip is completed in 32 hours. After removing the concrete disk (now located outside the dome) that was used to test the support structure, engineers install the mirror. Initial imaging results are promising but not ideal. It takes two years to finish polishing, aligning, and adjusting the mirror."
Here's a link to another forum with a rail modeller's succesful attempt to build a flat car and blank: http://www.railroad.net/forums/viewtopic.php?f=93&t=10662
Enjoy!
George Hale..."...secures a grant of six million dollars from the International Education Board, a funding agency endowed by the Rockefeller Foundation, for "the construction of an observatory, including a 200-inch reflecting telescope... and all other expenses incurred in making the observatory ready for use." Unlike the Mt. Wilson observatories, which are operated by the Carnegie Institution, the 200-inch is administered by the recently founded California Institute of Technology (Caltech). Hale and his teams of astronomers, engineers, and opticians set to work."
Photos 1 & 2
The blank was..."...with only a rough flat front surface, is shipped across the country on a special train from New York to Pasadena, always traveling slower than 25 miles per hour. The telescope project has captured the public imagination, and thousands of people line the train tracks to watch this special cargo. Guards are posted around the mirror during overnight stops to prevent any damage to the disk. The trip takes sixteen days."
In 1936..."...In the optics lab at Caltech, the front surface of the mirror is ground to the approximate concave form required. Using successively finer polishing grit, the opticians then carefully smooth the surface, constantly using optical tests to compare it to a perfect paraboloid shape. It is slow and painstaking work. To make the final mirror, almost 10,000 pounds of glass are polished away, including the top two inches which contain "scar tissue" left over from the casting and annealing process."
"Telescope production halts because most of the engineers and scientists, as well as their laboratories, are reassigned to war-related projects. Not even mirror polishing continues during the war. The 200-inch disk is stored and protected by timbers for three years. After the war concludes, telescope work restarts in September of 1945. After three months of cleaning the labs, mirror polishing resumes. Most of the pre-war telescope workers do not continue with the project, so a new crew must learn the routines. "
Photo 3 "The 200-inch mirror is transported from Pasadena to Palomar on November 18-19, 1947. The 40 ton cargo requires three diesel tractors to push it up the mountain. Despite a storm, which nearly aborts the transport, the 125 mile trip is completed in 32 hours. After removing the concrete disk (now located outside the dome) that was used to test the support structure, engineers install the mirror. Initial imaging results are promising but not ideal. It takes two years to finish polishing, aligning, and adjusting the mirror."
Here's a link to another forum with a rail modeller's succesful attempt to build a flat car and blank: http://www.railroad.net/forums/viewtopic.php?f=93&t=10662
Enjoy!