Re: ATM Ritchey-Chretien

[Steve Lee <SL@AAOCBN1.AAO.GOV.AU>]

> Steven Lee:  I think you mean James Gregory, who lived in seventeenth
> century England. If John Gregory is lurking somewhere on the web,  he
> probably found that attribution amusing, but as far as I know he is still
> living in Dripping Springs, Texas. John Gregory's design that you may be
> thinking about is the Gregory-Maksutov.

> On the origin of the Dall-Kirkham design, I don't have my resources at hand
> at the moment, but I think Albert G. Ingalls is probably the source of this
> name. Kirkham was an ATM, in Oregon if my memory serves me, and was an
> active correspondent of Ingalls and a member, for a while, of Ingall's inner
> circle of correspondents. Ingalls looked into the question of priority and
> concluded that Dall, and Kirkham both deserved credit, and tagged the design
> with the name that has stuck since that time. If anyone is interested, I can
> probably give you the citation for the article on the subject in Scientific
> American.

Tom,

I can't believe that I wrote what I wrote!  My excuse is that it was 4:30
in the morning and I must have still been asleep.  My brain (?) clearly
got side-tracked on the Gregory-Maksutov which I was going to throw in
as another example and I jumped names and then wandered off.  If you
substitute Allan Kirkham for John Gregory then at least some of the story
makes sense.  I believe that you are correct in that Ingalls put the
two together, but in my mind it should always be the Dall-Cassegrain.
What I should have said is..

Horace Dall invented the D-K all by himself.  Allan Kirkham got into the
act by explaining what Horace had done in mathematical terms after it had
been built.

And then I was going to throw in about the Gregory-Maksutov being yet
another example of double-barrel names, and then point out that in
Holland the Maksutov is called a Bowers and some refer to it as a
Bowers-Maksutov.  It was certainly a mixture of priority and national
pride which confuses this design.

James Gregory, inventor of the Gregorian, was a Scottish mathematician.
My (Scottish) wife would never allow me to let him be called English.

> As for the pronunciation of Chretien - it depends upon which side
> of the Atlantic you reside.

And to all of you who spotted the fact that Australia doesn't bound the
Atlantic at all and so want to know which side of the Atlantic I reside,
the answer is - the correct side, i.e. nowhere near it at all!

I have always pronounced it KRET-ee-en but have never know whether it was
correct - hence I didn't want to put my foot in it (which I now have).

Steven Lee
URL:        http://www.aao.gov.au/local/www/sl/
e-mail      SL@aaocbn.aao.gov.au