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Glass Discussion & Research. NO IDENTIFICATION REQUESTS here please. => British & Irish Glass => Topic started by: keith on May 29, 2013, 05:37:33 PM

Title: 7 foot Chances glass !
Post by: keith on May 29, 2013, 05:37:33 PM
Have a look at this,
http://www.ebay.co.uk/itm/230424887844;jsessionid=16A43D2DCC2E94310311A36EC6C21A20?ru=http%3A%2F%2Fwww.ebay.co.uk%2Fsch%2Fi.html%3F_from%3DR40%26_sacat%3D0%26_nkw%3D230424887844%26_rdc%3D1
Title: Re: 7 foot Chances glass !
Post by: chopin-liszt on May 29, 2013, 05:50:09 PM
My birthday is in december - that will give you all some time to save up for it for me.  ;D
What a fabulous, fabulous, glorious and wonderful thing. I was drooling over one in the wee museum Arbroath recently, I even  touched it - very gently and reverently when nobody was looking.

I never ever fail to be amazed by the vision of the person who "invented" scrunching up a single lens like this.  8)
Title: Re: 7 foot Chances glass !
Post by: Paul S. on May 29, 2013, 06:51:21 PM
it's what you get the collector who has everything ;)
Title: Re: 7 foot Chances glass !
Post by: chopin-liszt on May 29, 2013, 07:00:29 PM
No, Paul. that's a tummy button fluff brush.
My Dad used to make them out of an old scaling brush drill bit from the surgery (he was a dentist) some of plaster of paris and the top of a felt tip pen.
He drilled a wee hole in the end of the pen tip and pushed the brush drill bit through it; then put two holes in the side of the top for a metal loop, secured it all in place with the plaster of paris then put a cord through the metal loop.
Voila! A personalised tummy button fluff brush available at all times, worn convieniently around your neck.
Title: Re: 7 foot Chances glass !
Post by: millarart on May 29, 2013, 07:18:42 PM
ooooh I see they have had a few offers, would be great to know how much , just out of total nosiness ::)
Title: Re: 7 foot Chances glass !
Post by: Paul S. on May 29, 2013, 08:59:47 PM
I guess you might say......standard navel issue ;)
Title: Re: 7 foot Chances glass !
Post by: Paul S. on May 29, 2013, 09:05:16 PM
looking at David's book, and I could be wrong, but it appears that you need six of these to complete the glass turrent of the lighthouse  -  so on that basis a pricey building project ;D
Title: Re: 7 foot Chances glass !
Post by: David E on May 30, 2013, 08:38:25 AM
Darn, Keith, now everyone will be bidding for it!  ;D

Yes, this keeps getting listed periodically and I did speak to the seller about it.

But as a 3rd order lens assembly, this is not the largest! A 1st order lens is seen here (http://www.utilityglass.com/) (another of my sites if you were wondering). I think, conventionally, 4-6 panels were required but there are exceptions, such as a land-based lighthouse tower - no point in lighting the land, if the optics were static; earlier ones rotated the entire mechanism floating on a bed of mercury, like the Skerries one on my website.

The 'order' of the lens signifies how far the parallel beam of light could be projected, so a 7th order could be used at sea level within a harbour, whereas a 1st order would often be up a cliff, inside a tower, projecting a beam up to 25 miles (40km) away.

The first photo posted here show René Vas and myself at the Hook of Holland lighthouse in front of a Chance 1st order lens - about 8ft (2.44m) tall?

The second shows us at the top of the Hook tower with René inside the lens assembly. I think this is a 3rd or 4th order lens. As you can see, the rear of the assembly is left open.

The third shows the lighthouse in its entirety. Well worth a visit - René purchased the tower for the price of one guilder, I think, after starting a campaign as a teenager when it was scheduled for demolition. This started a lifetime's commitment and it is now a museum. Put your climbing legs on, though, as there are seven levels...

The fourth photo was on the drive back and shows one of those coincidences you must photo!
Title: Re: 7 foot Chances glass !
Post by: David E on May 30, 2013, 08:45:01 AM
Quote
I never ever fail to be amazed by the vision of the person who "invented" scrunching up a single lens like this

Augustin-Jean Fresnel (1788–1827) but further refined by other mathematicians, including Sir James Timmins Chance (1814–1902). The whole idea is to focus the light into a parallel beam*, hence the strange angles of the optics. Note that each layer of optics is different and ground to a particular angle!

*Edit: But at an angle that took into account the earth's curvature - if the beam was parallel to the ground, it would disappear into space, hence the reason it needs to be mounted so high for one projecting the light over 25 miles.
Title: Re: 7 foot Chances glass !
Post by: chopin-liszt on May 30, 2013, 10:18:16 AM
I'm even more impressed now 8)  and just think how many folk owe their lives to these amazing lenses.
Title: Re: 7 foot Chances glass !
Post by: David E on June 05, 2013, 09:47:47 AM
Another Chance lighthouse optic, this time a 4th order lens assembly (http://www.trinitymarine.co.uk/extremely-rare-chance-bros-lighthouse-lens-granton-harbour-lighthouselens). At just 26-in high (66cm) tall, it was designed for a harbour (Granton) for guiding ships in. The red sleeve indicates it was a port-side light, as opposed to starboard (green).

A mere £36,000. A great pity: they only have one and I wanted a pair...  ;D
Title: Re: 7 foot Chances glass !
Post by: chopin-liszt on June 05, 2013, 09:55:34 AM
I grew up in Granton!
(an area of Edinburgh)