"Howie Glatter" wrote in message
om...
Alan French wrote:

I believe that the Amateur Scientist column in Scientific American had
at
least one article on actually ruling a diffraction grating. (Just in
case
anyone is really ambitious.)

I thought you were a nice guy, Alan, and here you are leading the
unsuspecting down a primrose pathway. Here's what Uncle Al Ingalls
said in the June 1952 Scientific American:

" . . The specifications are fantastic, but even more fantastic is the
ruling engine that has been contrived to do the job. This machine,
less complex in structure than a typewriter, is the most precise
mechanism ever made. It is so transcendently difficult to build and
operate that it has challenged man's mechanical genius and humbled his
pride for more than a century . . Why has this simple machine
frustrated so many able men? The dream of building a ruling engine has
haunted hundreds and ruined many. Recently a friend . . talked of long
deferred plans to quit his vocation and build an engine. "Over my dead
body!" exclaimed his wife, to whom he had once unwisely revealed that
a man might spend 10 nonproductive years curing a chronic case of
ruling engine fever the hard way . . When an Australian nurseryman
named H.J. Grayson
died after years of this acute malady . . his widow bitterly burned
all his ruling engine papers.
The central difficulty that has defeated so many efforts is the
inherent deformability of any material of which a machine may be built
. . On the scale of ultra-ultra precision with which we must deal in
a ruling engine we may regard the machine as being made of rubber. In
effect it has just about the same problem as an intoxicated man called
upon to pass a test of sobriety: it must place the tip of its finger
(the diamond) on the tip of its nose (the groove position) within a
millionth of an inch, and it must do this with a rubber arm and body!"

I'm going to have to speak to Susan about your postings. Maybe she
can influence you to desist from these subversive suggestions.

Howie,

You mean you're not heading into your shop and starting work on a ruling
engine? G I am continually amazed at what some ambitious folks manage to
do, and the Amateur Scientist column certainly had some interesting
examples. I suspect, however, that more than a bit of insanity would be
required to try ruling your own diffraction grating. I think a seismograph
would be a more reasonable, and interesting project.

Clear skies, Alan