Re: [Phys-l] resonance animation

[Brian Whatcott <betwys1@sbcglobal.net>]

Bernard,

I set out to refresh myself by looking over the pendulum paragraphs in 
an old Starling & Woodall's Physics.

(this is a book of which a reader might say, "if it ain't there, it 
ain't physics")  I was shocked to see how much more lucidly an entry in 
Wikipedia read,  in this case:

<http://en.wikipedia.org/wiki/Pendulum>

To read it is to understand exactly what Captain Kater had in mind with 
his reversible pendulum, and how Bessell made superfluous the careful 
equation of periods with a standard to one sweep in 24 hours or better, 
by means of correcting results from a fixed reversible pendulum.

This is to share with you that I do not dismiss the pendulum lightly.
But consider this.

A few months ago I bought a new wrist watch for about $5.
It was a quartz movement in a thick stainless case, rather like the 
Submariner and similar Perpetual time pieces which still cost up to a 
thousand times as much.
It was easy to see that this watch held time better than such an 
excellent mechanical movement.
Accordingly, I DO dismiss the pendulum movement as superseded, though 
it may well serve an ornamental purpose. You will agree I know, that any 
compound pendulum clock for which the prime mover is both mechanical AND 
part of the pendular mass, has its problems.
Finally, I mention that I was taken with the animated diagram of this 
parametric pumping of the censer offered in this thread. It could be 
stimulated to continuous revolution by modulating the drive frequency 
appropriately - a fine example of the pendulum's period variability with 
amplitude variation.

Brian W
p.s. For others who found your URL was broken, I repeat it here in tiny 
format.
<http://tinyurl.com/8o24k6>  
One temperature compensation was the opposing iron/brass form. Both of 
these rods tend to oxidize with time unless plated, unlike the usual 
quartz counterpart.
**
Brian W

Bernard Cleyet wrote:
> Brian!
>
> I didn't find an analysis of such pendula.  I was referring to a  
> particular pendulum clock** in a high end antique shoppe in Carmel (A  
> very high end city -- million dollar cottages!).
>
> I'll be pleased to mail photo's of it to requesters.
>
>
> ** Called swinging clocks examples:
>
> http://www.made-in-china.com/showroom/labbcoco/product- 
> listvbqniEmYuJRe/Swinging-Clock-catalog-1.html
>
> bc  abbreviator.
>
>
>
> On 2009, Jun 03, , at 04:23, Brian Whatcott wrote:
>
>   
> > Bernard Cleyet wrote:
> >     
> > > ... pendula ... analysis ... but not coupling two pendulua in such  
> > > a manner.
> > >
> > > I examined the rod below the knife edge carefully and note the
> > > adjustment is in the form a two or three metal rods temperature
> > > compensator.
> > >
> > > Any comments?
> > >
> > > bc
> > >       
> > You seem to be alluding to a particular  example of coupled  
> > compensated pendula.
> >  What is  the URL please?
> >
> > Brian W