Re: [Phys-l] FW: universal gravitation lab

[Bernard Cleyet <bernardcleyet@redshift.com>]

That's correct. Epstein (or the host of the column, Stong?) wrote the 
"... Cavendish apparatus ..."  not Cavendish's apparatus.  Furthermore, 
this refers to fig. 3 of Epstein's apparatus.

bc, thinks BW jumps too quickly;  something Bill Walker accused bc of, 
often in class ("bc's favourite occupation ...."

Brian Whatcott wrote:

> At 12:37 PM 2/15/2007, BC, you wrote:
>
>  
>
> > Here's another from Sci. Am.  (Sept. 1963)
> >
> > "An inexpensive version of the Cavendish apparatus, modified to include
> > electrostatic shielding, has been constructed and used successfully for
> > evaluating G within 1 per cent of the currently accepted value by Sam
> > Epstein of Los Angeles.
> >
> >
> > Figure 3: Lower end of suspension
> > Epstein writes: "Essentially the Cavendish apparatus is a sensitive
> > torsion balance and a balance arm suspended at the middle by a slender
> > steel wire.  ////
> >    
>
> Bah, humbug!    This may be Epstein's Cavendish apparatus,
> but Cavendish's Cavendish apparatus was slung initially from
>  a silvered copper wire of about 10 thousandths inch diameter.
> Details...details!   :-)
>
> <http://books.google.com/books?vid=OCLC27796316&id=zrkEAAAAMAAJ&pg=RA2-PA125&lpg=RA2PA125&dq=cavendish+experiment+suspension+wire#PRA1-PA67,M1>
>
> page 67
> a silvered copper wire, 39 1/4 in long, weighing 2 4/10 grains/ft.
>
>  
>
> > bc
> >    
>
>
>
>  
>
> > Brian Whatcott wrote:
> > ...
> >    
> >
> > > Now that WAS a physics setup.  Torsion to spare in fact.
> > > Which reminds me that I seem to recall that Cavendish discarded
> > > his first copper torsion wire as too compliant, allowing the arm
> > > to hit the draft-box.
> > >
> > >
> > >      
>
>
> Brian Whatcott    Altus OK    Eureka! 
>
>
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