Re: ATM The Perfect Machine

[Anthony Stillman <atmer@flash.net>]

I hadn't meant this to be a book report, but I'm afraid to some extent that
is what it has become.  I have tried to stay somewhat on topic and keep the
post's length in check.

"The Perfect Machine  Building the Palomar Telescope" by Ronald Florence
HarperCollins Publishers

Part of my rational for re-reading the book was the exchange Richard
Schwartz stimulated about the Hale not being an aplanatic instrument.
Having been called on my subsequent simplistic remarks, I started to wonder
if some rational for adopting the classical design could be found.  The
book intimates several.  First, when the 200 inch Hale was in its inception
the Ritchey-Chretien design was unproved; no telescope of that design had
been successfully built.  Second, there was some question whether the Ross
corrector used at prime focus to widen the useful field of the f/3.3
primary could be designed.  I surmise from this that a hyperbolic primary,
for which a corrector at prime focus would not have been optional, was an
untenable choice.  And finally, Ritchey, a temperamental individual,
alienated the other players.  Florence writes  "...no one in Pasadena
wanted much to do with one of his designs..."  It also seems this sentiment
was reciprocated.  Prior to the completion of the 100 inch Hooker, Ritchey
and Hale had a falling out, complete with back-stabbing and rumor-mongering.

I enjoyed reading about Bowen's use of fishermen's scales to pull out the
last bits of the primaries residual stig.  Not just because it was a kluge,
but because the kluge was left there.  That years later the scales were
removed because they  "didn't belong"  and then replaced because they did
belong, made it that much better.  I've long documented my kludges with a
simple explanation buried inside the instrument because, the poor sap who's
trying to fix the damn thing twenty years from now may just be me.

The book describes Brownie (Marcus Brown) mixing rouge with talc (hydrous
magnesium silicate) to yield a smoother surface and slow the final
figuring.  In a later chapter, after the mirror had been delivered to the
mountain, the book has Hendrix and Johnson using barnesite and their thumbs
to do zonal work.  ATM III describes barnesite as 40 to 45 percent cerium
(di)oxide, the rest other rare earths.  I've worked with barnesite and have
found it fairly aggressive.  Even using my little finger as a tool it
leaves a rather rough finish.  It seemed odd to me that Brown would have
put in so much time touching up the mirror, begrudgingly let Anderson call
it good and send it to the mountain, knowing the mirror still needed
extensive work, so I did some research.  In a work published in Twyman's
"Prism and Lens Making", J. V. Thomson writes that on site figuring was
confined to the outer 18 inches of the mirror.  The edge of the mirror had
intentionally been left high as it was expected to sag in the telescope.  I
guess it didn't, at least not enough.  Also, curiously Thomson writes that
for the very final figure the Strong and Gaviola system of controlled
deposition of aluminum was used.  This and the use for barnesite leaves me
wonder if the mirror has since been refiguired.

The book contains numerous errors.  Enough to be disquieting.  Mostly what
I noticed were errors in science, the sorts of things a good technical
editing should have caught.  One of the most glaring (345.9) "The small
mirror of an amateur telescope might be figured to one fourth of a
wavelength of light, a precision of hundreds of thousandths of an inch."
doesn't even make sense.  There are many other errors, some subtle and at
least one omission concerning a funding source, namely the contributions
made by California school children during the depression.  All this has
left me unease about the history.  In a private communication, Andrew Bell
directed me to Osterbrock's "Pauper and Prince" which Virginia Trimble in a
review of "The Perfect Machine" cites as a more reliable account.

There was little new, applicable to ATMing, for me to glean from this
reading.  Using talc with rouge for smooth slow figuring and in the last
chapter a description of using bar codes to sense the position of the dome
stick in my mind.  Though not new to me, the notion that there are never
enough sources for good idea's and that stalls in any process are
inevitable also stayed with me.

One other theme which runs through the book bares comment.  Many of the
principals were petty, rancorous, egotistical, malicious, and self-serving,
often to the detriment of the project.  I mention this, both to discourage
such exchanges on this list and help all of us see that those who have
been, and likely will again be involved in such exchanges, are in good
company.

Anthony