The 200 inch Time Machine

Talk by Mr Sparrow
July 2007

Completed  Palomar Exterior1928: Rockefeller grant for 200-inch telescope
Hale (pictured) secures a grant of six million dollars from the International Education Board, a funding agency endowed by the Rockefeller Foundation. The 200-inch is administered by the recently founded California Institute of Technology (Caltech).
200 inch Mirror Cast1934-36: A Pyrex Mirror
Corning Glass Works of upstate New York build the 200-inch mirror out of a new glass blend called Pyrex. On their second attempt, Corning succeeds in casting the 200-inch mirror. The image to the left shows two people standing on the original unpolished surface.
Dome Building1936: Dome construction
The finished dome is 41 meters (135 feet) tall, 42 meters (137 feet) in diameter. The dome weighs approximately 1,000 tons, with a plate steel exterior and aluminum panel interior, separated by four feet to allow for dome venting. Two 125-ton shutters cover the opening and slide open at night.
Mirror travelling East to West Coast1936: Mirror transport
The mirror blank, with only a rough flat front surface, is shipped across the country on a special train from New York to Pasadena, always travelling slower than 25 miles per hour. Guards are posted around the mirror during overnight stops to prevent any damage to the disk. The trip takes fourteen days.
Mirror polishing1936-47: Mirror grinding and polishing
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.
Telescope Construction1937: Telescope construction
Components of the telescope are constructed at sites all over the country and then shipped for assembly inside the dome. Parts from Westinghouse's Philadelphia factories, Corning's New York glass foundries, and Caltech's and Carnegie's Pasadena labs have to make their way up to the mountain summit. The telescope tube is shipped by boat through the Panama Canal, with the Navy's help. Many of the large telescope parts are built in shipyards. This leads to the battleship grey paint scheme for the telescope.
Mirror transport and installation1947-49: Mirror transport and installation
The 200-inch mirror is transported from Pasadena to Palomar on November 12, 1947. The 40 ton cargo requires three diesel tractors to push it up the mountain. Despite a storm the 125 mile trip is completed in 32 hours.
Dedication Ceremony1948: Dedication ceremony
Although the 200-inch telescope is still not yet fully operational, it is dedicated on June 3rd and formally named in honor of George Ellery Hale, who passed away in 1938. Almost one thousand people attend the dedication, including many dignitaries from around the world. The first demonstration of the telescope and dome includes a ride on the dome as it spins. The ride is smooth enough to confuse some into thinking the telescope floor is rotating. This picture shows as well as any the relative sizes of the telescope and the seated human audience
  


Here are finally three pics that indicate the scale of the project. More comprehensive information is available from Caltech Astronomy. All the images are copyrighted by Caltech Archives.

Editors note:-
As there was some difficulties experienced with the audio and visual projection accompanying the presentation here are a few pics obtained from http://www.astro.caltech.edu/palomar/history.html together with extracted notes.




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