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From: hopp@nbs-amrf.UUCP (Ted Hopp)
Newsgroups: net.jokes,net.puzzle
Subject: Re: Manhole covers (interview question)
Message-ID: <474@nbs-amrf.UUCP>
Date: Sun, 17-Mar-85 23:34:28 EST
Article-I.D.: nbs-amrf.474
Posted: Sun Mar 17 23:34:28 1985
Date-Received: Wed, 20-Mar-85 04:41:21 EST
References: <462@nbs-amrf.UUCP>, <7074@watdaisy.UUCP>
Organization: National Bureau of Standards
Lines: 73
Xref: watmath net.jokes:11432 net.puzzle:625

> (Note that this follow-up is not posted to net.jokes, only net.puzzle.
> Perhaps it belongs in net.flame.)

> > > 	Why are manhole covers round?
> > I can think of at least three answers:
> > 	1.  Because they aren't any other shape.
> > 	2.  Because manholes are round.
> > 	3.  So that manholes can be round.

> Answer 1 is false; I have seen square manhole covers.
>
> There is of course at least one valid answer (which has already been
> posted), and these answers 2 and 3 demonstrate how an un-clever person
> would rather be an asshole than respect those who figure it out (or
> who try).  Yes, this qualifies him for a job (flushing toilets), but
> probably brings him a much better job (marketing, or mis-managing
> engineering departments, etc., using his talents).
>
> -- 
>
>    Norman Diamond

As the "asshole" that seems to irritate Mr. Diamond so much, I feel I
should respond, although I'm not sure why.

The original question was posted to net.jokes as well as net.puzzle, so
I answered it in the spirit of net.jokes.  I don't see how that shows a
lack of respect for those who approach it as a puzzle, or why they (or
perhaps just you, Mr. Diamond) should feel denigrated.

As a point of logic, if there are square manholes, how can there be ANY
valid answer as to why manholes are round?  My answer 1 was a variation
on one of the Baron von Munchousen stories.  ("Where are we?" "In Bavaria."
"How do you know?" "Can you say we are anywhere else?" "No." "If we
are not anywhere else, we are in Bavaria.")

As a point of information, the original poster of the question admitted
on the net that one of the answers he was looking for was my answer 3.
(I guess he is an asshole, too.:-)

As a further point of information, what is this valid answer that was
posted to the net?  If it is that a round manhole is the only shape that
will prevent it from falling into the hole, it has also been pointed out
on the net that this is false.  There is at least one infinite set of
simple closed curves that have this property - the curves of constant
diameter.  An example of a curve of constant diameter that is not a
circle is the rotor of a Wankel engine.

Also, why doesn't a manhole cover (of any shape, but let's stick to round
ones) fall into the manhole? It is because there is either a ledge on which
it rests or the opening is beveled.  In either case, I claim that all
regular polygons of sufficiently high order approximate a circle closely
enough that they will not fall into the hole, either.  Obviously, not
falling into the hole cannot be why (i.e., the cause that) manholes are
round, only an effect of them being round.

As a point of personal preference, Mr. Diamond, I offer two more answers
that, judging from your reaction so far, should really make you see red:

	4. [Round] manhole covers are round so that workmen can move
	   them easily by rolling them.

And, since you refer to my managerial talents, Mr. Diamond:

	5. Manhole covers are round because it is cheaper to machine
	   a round shape than any other shape.

I suggest that your posting didn't belong in net.jokes, net.puzzle, or
net.flame.  It belonged in net.knee.jerk.reactions.

-- 

Ted Hopp	{seismo,umcp-cs}!nbs-amrf!hopp