Hello Peter,
Another aside, if I may, on the use and selection of Quartz. There is
an interesting description in "The Perfect Machine : Building the
Palomar Telescope" about how General Electric hand selected train loads
of Quartz in their failed attempt to manufacture fused quartz mirror
blanks for the 200" telescope. Apparently, a single person (to insure
consistency) examined each piece while it was submerged under water. Ah,
the slow road of progress!
Regards,
Luke
Peter Tandy wrote:
>
> Dear fernando,
>
> I don't know too much about the radio side of quartz production, but it was
> needed during the war to make oscillators for the radio industry (and
> military, of course). These plates must be cut at a highly specific angle
> from a certain part of the crystal. Problem is, that many quartz crystals
> are twinned, that is, they are really two crystals growing about a common
> plane (as opposed to two crystals which by chance intersect each other in a
> random growth). Sometimes this is self evident (if you know what to look
> for), but often ordinary quartz crystals show little sign of their being
> two individuals (they come in right and left handed forms, like gloves).
