David,

Also one you can get right up to at the maritime Museum in Norfolk, VA.

Karl Wolz

----- Original Message -----
From: "David Beierl" <dbeierl@ATTGLOBAL.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Wednesday, May 08, 2002 9:12 AM
Subject: Re: fresnel lens

> At 11:17 AM 5/8/2002, Ben McCafferty wrote:
> >While we're on the topic of Fresnel lenses, those of you in or near CA,
take
> >a trip in your Westy (RVC) to the Pigeon Point Lighthouse, about 15 miles
> >south of Half Moon Bay.  You can take a tour, and they are one of the
only
> >lighthouses I know of where you actually get to go up into the top where
the
> >Fresnel lens is.  It is an order 1 lens (I think--it's the biggest one
ever
> >made), and is nothing short of spectacular.  Once a year, in November,
they
> >light the bulbs inside the lens and it is a working Coast Guard beacon
for 2
>
> The biggest (bigger than first order) was called a hyper-radiant.  There's
> a first-order lens in the light at Seguin Is. Maine which you can visit --
> but you have to get out to the island, and the caretakers have to be
> around.  They're the "Friends of Seguin," not official keepers -- like all
> US lights it's officially unmanned.
>
> There's another large lens, not sure what order, in the Boston Science
> Museum, but it's not lit and I don't think you can get too near it.
>
> These -- the original Fresnel lenses are based on the same principle as
the
> modern flat ones, but they're made of individual curved prisms mounted in
a
> globular framework.  Worth a few million each...
>
> david
>
>
> --
> David Beierl - Providence, RI
>   http://pws.prserv.net/synergy/Vanagon/
> '84 Westy "Dutiful Passage"
> '85 GL "Poor Relation"
>