On Aug 21, 5:39 pm, (Richard Casady)
wrote:
On Thu, 21 Aug 2008 10:49:35 -0700 (PDT),
wrote:



On Aug 21, 1:46 pm, wrote:
My daughter is sick so I have to stay home if she needs me. There is
light rain from Fay so no working on the boat.

So..........start a project I have been planning, a boat telescope.

I like casual astronomy just a little better than 7X50 binocs and I
know about optics and ground a telescope mirror when I was a kid. So,
this project is a 4" diameter mirror of only 20" focal length and low
magnification for very wide field of view.
After 1st half hour of rough grinding, I have a definite bowl in the
mirror.

I tried that liquid mirror thing once, or at least an infra-red
variation. I put a bowl of epoxy on my old turntable and spun it for
several hours till it hardened. It sorta worked but I did not manage
to get the bubbles out so he surface was covered with tiny pockmarks.

Put it under a bell jar and pull a vacuum on it.
Casady

I was only 17 when I did that so had no bell jar.