Wednesday, December 2, 2009

200" Mirror Cast 75 Years Ago Today

75 years ago today, December 2, 1934, Corning Glass Works successfully cast the 200-inch mirror for what would become the Hale Telescope on Palomar Mountain.

I have blogged about this before (see: December 2, 1934 and Pouring Glass: the Movie), but today I wanted to share a photo of the then still molten 200-inch mirror and its creator: physicist George V. McCauley of Corning Glass Works.

It is an interesting photo because the molten glass is hot and glowing, revealing the pattern of the many hollow spots on its underside. Dr. McCauley, or "Mac" as he was called, later described what is shown in the above photo.

"The changing appearance of the disk during this cooling period was fascinating and beautiful. When ladling was completed, the glass above the cores was hotter than the cores themselves and one saw the perfect pattern of the latter in darker contrast with the molten glass. As time passed and the surface glass cooled, while the cores - cooling less rapidly - became the more radiant and were seen as the highlights between the darker ribs of glass, the picture was so beautiful to look upon that it was with regret that it had to be sealed from sight within the two telescoping sections of the annealing kiln."

His description was actually of the view just after they had poured the glass the the 120-inch mirror (now at Lick Observatory), but the Palomar mirror is also honeycombed and went through the same effect. Too bad there aren't any color photos of this.

6 comments:

Scott Kardel said...

This is an easy date for me to remember: my mom's 5th birthday.

Happy 75th birthday to the 200" mirror & happy 80th birthday to my mom!

Bob said...

I second that!

Dan Fischer said...

This item really 'shocked' me - in a positive sense, as the Hale is still doing great science today. Which makes me wonder whether great telescopes are actually unique among 20th century technology marvels in that they can run practically forever. And whether the same will be true for the big scopes of today ...

Scott Kardel said...

An interesting question Dan. The Hale was certainly built to last the ages and with new instrumentation (as we keep getting) it should last for a long time to come.

One can hope that will also be true for the newer bigger scopes.

kristine said...

Congratulations Scott on your 2nd 75th anniversary of 2009! You are a top-notch keeper of Palomar facts & celebrations. Corning is justly proud of our 'baby' & its caretakers. Carry on.......

Did you give mom a viewing on her b'day!?!

Scott Kardel said...

Thanks Kristine. We will do our best to keep taking good care of "Corning's baby".

No, my mom didn't get to look, we're too busy doing science with the 200-inch for that.