end his
membership for a year. The three letters from Cairo, London, and Luna
City were simply chatty little social notes, nothing more.

The three from Scholar Duckworth were from a different breed of cat.

The first was postmarked 21 August 2187, three months after Turnbull had
left for Lobon. It was neatly addressed to Dave F. Turnbull, Ph.D.

* * * * *

Dear Dave (it read):

I know I haven't been as consistent in keeping up with my old pupils as
I ought to have been. For this, I can only beat my breast violently and
mutter _mea culpa, mea culpa, mea maxima culpa_. I can't even plead that
I was so immersed in my own work that I hadn't the time to write,
because I'm busier right now than I've been for years, and I've had to
_make_ time for this letter.

Of course, in another way, this is strictly a business letter, and it
does pertain to my work, so the time isn't as hard to find as it might
be.

But don't think I haven't been watching your work. I've read every one
of your articles in the various journals, and I have copies of all four
of your books nestled securely in my library. Columbia should be--and
apparently is--proud to have a man of your ability on its staff. At the
rate you've been going, it won't be long before you get an invitation
from the Advanced Study Board to study for your Scholar's degree.

As a matter of fact, I'd like to make you an offer right now to do some
original research with me. I may not be a top-flight genius like
Metternick or Dahl, but my reputation does carry some weight with the
Board. (_That, Turnbull thought, was a bit of needless modesty;
Duckworth wasn't the showman that Metternick was, or the prolific writer
that Dahl was, but he had more intelligence and down-right wisdom than
either._) So if you could manage to get a few months leave from
Columbia, I'd be honored to have your assistance. (_More modesty,
thought Turnbull. The honor would be just the other way round._)

The problem, in case you're wondering, has to do with the Centaurus
Mystery; I think I've uncovered a new approach that will literally kick
the supports right out from under every theory that's been evolved for
the existence of that city. Sound interesting?

I'm mailing this early, so it should reach you in the late afternoon
mail. If you'll be at home between 1900 and 2000, I'll call you and give
you the details. If you've got a pressing appointment, leave details
with