Re: ATM Two Questions

["Bob May" <bobmay@nethere.com>]

As to working with speculum metal, the oldtimers (before the silvering of
glass) did make mention of how to do so and you can often go read their
notes in various books.  Note that they kind of said things differently than
we do today so it may be some rough reading, especially since many phrases
and materials have gone out of general usage or have changed their names.
There have been reprints of some of the works from back then although I
don't have any.
As to the mirror, look at it's shape and figure out what kind of Cass you
can do with it.  Personally, I'd try for a refigure to a hyperbolic and
figure on making a R-C type Cass.  Then there's the Parabolic surface to
which you can make either a classical Cass or a Gregorian (nice because the
secondary is a Concave elipsoid) and the elipical of that is the positioning
of the two focal points of the shape.  The Gregorian secondary merely
reproduces the focus of the primary at a second location (the other elipsoid
focus point).
Bob May
http://nav.to/bobmay
bobmay@nethere.com