Eratosthenes and plumb bobs

[Herbert H Gottlieb <herbgottlieb@JUNO.COM>]

 

On Tue, 05 Jun 2001 18:40:03 -0500 brian whatcott <inet@INTELLISYS.NET> writes:
> At 15:26 6/5/01 -0700, Ken Murray wrote:
> >My students would like to measure the size of this planet with a
> >length-of-shadow measurement (a variation on Eratosthenes's
> observations).We would measure the shadow angle of a vertical metre stick
> /snip/
> >Ken Murray
>
> It's an interesting detail of the experiment to decide how the
> verticality of the sun stick should be verified.   I've heard

mention of a windshielded tray of water at the foot,  using the

eye's perception of the straightness of the stick
> compared to its reflection.  A windshielded plumb bob seems

to have possibilities too.
> brian whatcott <inet@intellisys.net>  Altus OK Eureka!
>

 

I've heard of a windshield on a car and on a motorboat.

But ? ..... a windshielded tray of water?  

 and a windshielded plumb bob???

 

Did Eratosthenes have a windshield on his vertical stick?

Has anyone ever measured the deflection of a plumb bob

as a function of varying wind speeds??  Is it a viable

project for a student science fair?   Is it necessary to perform

such experiments during a tornado or hurricane? 

If so, is a windshield wiper of any help at such times?

 

Herb Gottlieb from New York City

(Where builders use plumb bobs without windshields)