From: "Richrad" 
To: "Russell Jocoy" ,
        
Reply-To: "Richrad" 



----- Original Message -----
From: "Russell Jocoy" 
To: 
Sent: Saturday, February 01, 2003 8:52 AM Subject: ATM 200 inch mirror Mount Palomar
> ... which involved building a mold like a waffle iron with cores of
> silica brick. Anchoring the cores
> turned into a nightmare struggle with heat:  one disk was ruined in
casting
> when the steel anchor bolts
> melted and the cores bobbed to the surface of a sea of liquid glass.

Hmmm.. the melting point of steel is about 1600 degC, and glass is fluid
enough at 1100 degC.   I don't think the steel melted.   Perhaps it was
chemically attacked by the glass.


>                Finally in December of 1934 a perfect disk was cast in 7

For many years the 40" center that was cut from the blank was on
display at Griffith Obervatory in Los Angeles.   If you saw it, you would
realize that
the blank was far from perfect.  It was full of included cracks, striae,
bubbles, dirt clods, dead rats, etc.


> hours of suspenseful labor, and put
> into a specially built oven to cool.  After 10 months, yes I said 10
months,
> of cooling it was sent on a
> flatcar to California for the long job of polishing.  This disk was 20
tons
> and had a 40" center hole.
>        The polishing tool was faced with almost 2000 glass blocks about
> 4"x4".  Polishing was done
> at the California Institute of Technology.  It took 11 years to polish
this
> monster, with the interuption
> of war, and over 5 tons of glass were removed by 30 tons of abrasives
before
> the disk was ready
> for mirroring.

I do not understand how the war stopped the polishing.  As far as I know,
the Japanese never attacked Pasadena.  However, the cheerleader from my
mother's days at Pasadena City College was deported to a concentration
camp. After the war they returned and rebuilt their business, the Wakiji
Nursury. There was an unemployed master optician living nearby, George
Ritchey, but he was not allowed to work on the Palomar 200 because of
professional jelousy on the part of money men Hale and Adams.

>                 It took only one ounce of vaporized aluminum to coat  the
> 30,000 square inch surface.

And how many ounces to perfect the process before the mirror was coated?

>      Just some food for thought............. RUSS JOCOY

We have come a long way since those primitive times.   Obviously the Palomar
200 was no good because they didn't follow the 6:1 rule and position the
flotation points at the 70% zone as Hindle instructed!   Heil Hindle!

. . . Richard

--- BBBS/NT v4.00 MP