Re: [Phys-l] Q: Why are manhole covers round?

["John Clement" <clement@hal-pc.org>]

There may be an answer to this question, but in the end it may be difficult
to actually find it.  While there certainly are other shapes, they are not
as common.  I can't recall where I have seen other shapes, but I think I
have.

As such it is just as valid a research question as the lives of quarks or
the lives of toads.

The Wikipedia depicts more round than square, but the obvious reason for
square is also depicted.  If you have a walk or street paved in rectangular
slabs a square or rectangular cover blends in better.  The triangular ones
it is claimed were used to point in the direction of flow (of what?).  They
are being phased out because they don't meet standards.

The answer could be as simple as tradition.  It could also be that the
circle may have been easier or more economical in earlier times.

This is actually a harder question than why do chain or line dances lead
from the left in Western Europe and from the right in Eastern Europe.

John M. Clement
Houston, TX

> If you Google "why are manhole covers round" you get 23,500 hits.  I did
> not look at all of them, but the ones I looked at tend to fall into
> three groups; the third of which is an extension of the second.
>
> (1) some logical reasons why round is a good idea
> (2) that an answer is not really desired, it is really an interview
> question to see how the respondent thinks
> (3) legends/jokes about how certain people (like Feynman) would have
> responded to the question