Re: Speculum metal mirrors

I would advise against a speculum mirror for anything but historic
romanticism. They had to be polished weekly I believe.

On Wed, 17 Aug 2005 17:43:10 +0000, Ed Majden wrote:

> Back in the old days when they did not know how to coat glass mirrors
> with silver or aluminum speculum metal was used to make telescope mirrors.
> Does anyone know the type of grinding compounds they used to generate a
> metal mirror? i.e. carborundum or something else???? I want to generate a
> small convex surface probably out of brass or aluminum with a radius of
> curvature of 12 inches and 2-1/4 inches in diameter. This is for a Schmidt
> Camera film holder which has a curved convex focal plane. I believe it
> would be simpler to grind such a curve in metal rather than spend the time
> making a complex jig setup for a lathe so such a curve could be machined.
> Thanks:
>
> Ed Majden B.C. - Fireball Network Coordinator - AMS Meteor Spectroscopy
> West Coast Sandia Bolide Detection Station
> Courtenay B.C. CANADA
>
> http://members.shaw.ca/epmajden/index.htm

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