Thursday, 18 March 2010

Let there be light


Before electric lighting became common around 1900, light was provided free of charge by the sun, and at night by candle, lamp, or other flame. Anything which could extend the reach of the sun's free and safe light to interior spaces would make that space more useful and valuable. Prism glass is architectural glass used to redirect sunlight to interior spaces through refraction and reflection.

Left: Martin Place; Right: Mark Foys
Banks of prism glass came to be known as vault lights, aka sidewalk lights or pavement lights. They're those glass chunks set into old pavements to let light into vaults and basements below. Prisms were used instead of flat glass to disperse the light, diffusing it over a large area; plain flat glass would simply form a bright spot on the floor below, not providing much useful general lighting.

Left: George St portico of GPO; Right: diagram from Glassian
They're usually purple, but aqua and clear are known. Purple glass was originally clear; manganese added as a decolourizer slowly turns purple after years of UV exposure from sunlight. In the UK. pavement lights were originally set in iron frames, often marked with the name of the foundry rather than the glassmaker. Later replacements are set in concrete and steel which is the style common in the USA.


In Sydney, I have identified installations from:
B C Plummer $ Co., Sydney
Leopold Barnett & Co. Ltd
Hayward Brothers, UK
St Pancras Ironwork Co., London


Go see for yourself. They are scattered up the eastern side of George St, along the northern side of Martin Place between George & Pitt, along Mark Foys Elizabeth Street frontage, and along the northern side of Oxford Street. They are probably elsewhere, too. Their use declined as electric light became cheaper and better, and by the 1930s were on their way out. Now, they are endangered relics.


I am indebted to The Glassian site for the technical text of this post.

27 comments:

SA.ART said...

This was interesting to look at.

Janet said...

How interesting - we have NOTHING like that here!

James said...

That is really nice. I have the feeling that I don't pay enough attention to what's on the ground in front of me when I walk around with my camera.

I understand what you mean about restoring old signs. I'm torn too. However I do like the restored sign in my post. Maybe because I never say the original.

Piyush said...

Hmm .. that was an interesting post. Quite an innovation. There is so much we can take from nature, if only we wanted to.

Woody said...

What a fascinating post! They look like normal glass tiles and are very beautiful. Hopefully, they will be preserved.

brattcat said...

This is such an enlightening post and I mean that, though I won't deny the pun factor. I've seen these before in cities and never even asked, though I always admired and was intrigued by them.
As for your comment on my blog, have I told you lately how remarkable you are? I feel so fortunate to have your careful and inquisitive eye coming to visit Vermont.

lizziviggi said...

A very interesting and informative post, as usual! Like Brattcat, I've seen them and never asked what they're for. Now if only we can go back to that kind of sustainable, imaginative, resource-free thinking! I think I've seen a few of these in my own town-- now I'll have to go look. Someday if I'm visiting Sydney and I see a woman walking slower than everyone else, with her eyes cast down or up, looking at something everyone else is passing by without a thought-- I'll know it's probably you, Julie.

Jørgen Carlsen said...

Interesting to read about the usefullness of the small glases - I never thouht of them that way. Today I have posted a photo of an "electricity highway" at one of my blogs.

Birdman said...

Nice work Julie. It's amazing where we find our subjects in this complicated world.

Rinkly Rimes said...

I feel guilty when I think how often I've passed such 'windows' and never even given them a thought. To blog is to become educated!

J Bar said...

Good collection Julie and interesting post.
Sydney - City and Suburbs

Joan Elizabeth said...

What a great story. Of course I have noticed these things before but not understood the detail or reason for them. At BMJ after tomorrow we are off to visit the Shale Oil Refinery ruins (but it will be while before we get there) -- they used to make kerosene and paraffin from the shale for lighting before electricity. Just as these things died out in the '30s so did the refinery.

That's also really interesting about the purple glass.

Ann said...

Obviously I've seen these as well but have never really thought about them. Fascinating post.

Marka said...

I've never seen them before. Thanks for sharing and informing.

Bill said...

The say, you learn something every day. Well, today I learnt about these glass floor tiles which I have seen in Sydney but never gave a second thought. Thanks Julie for sharing informing us on these.

cara said...

I know these quite well as I used to work in a shop in London and the staffroom was underneath. The effect of people walking over the top of you takes a bit of getting used to. You realise they have no idea you are sitting under their feet having a cuppa and watching their shadow pass over the crossword you are trying to do.

jabblog said...

This was most informative. I had never thought about them before though there are plenty of them around. I shall pay more attention now just as I do to manhole covers thanks to your post about them.

Nishant said...

It's amazing where we find our subjects in this complicated world.
work at home in india

Naturedigital said...

Great photography and art..
Costas

Serge Cornillet said...

Always fresh ideas at your blog.
Nice.
Serge

Ellie said...

I just discovered your blog - what fun! We live in Turramura - but are from the US. I love your photos!

Virginia said...

Sadly I don't 'think we have such here in Birmingham. A most interesting post Julie. THey are works of art!
V

Marla said...

This is one of my favorite posts so far. I love prism glass.

Unknown Mami said...

Fascinating. I always wondered why glass like that was not just smooth and clear.

Julie said...

Cara, so good to have that comment about what it is like to be underneath a pavement light. I did not even try to venture down to have the experience myself.

Shelle said...

glad they are still there...i do remember these when i was young.

Pasadena Adjacent said...

Wow wee! I completely adore this post. I've always loved the way the glass changes to purple over time. It looks like here they've replaced the glass over the years.

In pasadena many of these pieces are actually circles without a metal grate surrounding them. Makes me wonder if they didn't pave over that part. Anyhow I think I'll take a screen shot of the info provided. You made my day!