Wednesday, January 14, 2015

The Perfect Machine

“Putting the observer inside the telescope had obvious advantages.”  The Perfect Machine: Building the Palomar Telescope by Ronald Florence (HarperCollins, 1994; HarperPerennial ppb 1995).  Author Ronald Florence grinds through the history to produce a polished narrative.  Unfortunately, as is too often true with popular reads, the chronology gets lost.  The book has an index and notes at the back.  Again, though, as a popular publication, the sparse notes are not tied directly to the text with numbers.  The work is entertaining, even compelling.  If this story of Mount Palomar excites you, then Internet references and websites for the great telescopes will give you even more to read.  This book will provide the context for those details.  

George Ellery Hale’s lifelong quest gave the world a set of telescopes, each larger than the previous. The 40-inch refractor paid for by Chicago entrepreneur Charles T. Yerkes was Hale’s first triumph, but not his first telescope.

“An astronomical telescope
is an impossible combination
of the scale of a battleship
and the precision of a microscope.”
Born in 1868, the eldest of three children, Hale grew up pursuing intellectual passions for machinery and tools, including microscopes.  His father made his money installing elevators as Chicago was rebuilt after the great fire of 1871; that gave George Hale access to local leaders. When Hale was fourteen he introduced himself to Wesley Sherburne Burnham, a court reporter and an avid astronomer.  Assisting Burnham, Hale was introduced to optician Alvan Clark, from whom he purchased a used four-inch telescope.  A decade later, Hale obtained from Clark the 40-inch glass blanks that became the Yerkes refractor.  
Next came the 60-inch reflector at Mount Wilson, then the 100-inch at Mount Wilson.  Hale died in 1938.  The 200-inch telescope at Mount Palomar was completed in 1948. It was more than the largest telescope.

“Gradually Anderson and Porter began looking at the scale of the telescope – the latest estimates were that the primary mirror would weigh close to twenty tons and the mounting more than five hundred – as an advantage.  The size of the telescope tube and the stability of the immense mounting meant that the auxiliary mirrors for the Cassegrain and Coudé  foci could be mounted in a permanent cell in the middle of the telescope tube, with gear-driven mechanisms to swing and lock them in place as needed.  The mirrors and cell, approximately six feet in diameter, would rob the central portion of the two-hundred-inch disk of only one-ninth of its area, an acceptable sacrifice. And since the telescope could tolerate a six foot cell, by extending the cell on the other side of the compartment that held the swinging mirrors, they had room for an observer to ride inside the telescope to use the prime focus.”

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