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What are those grids of glass in the sidewalk and why are they purple?

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Re: What are those grids of glass in the sidewalk and why are they purple?

#91

Post by yellowapple »

Zwi wrote: post #60
lqet wrote: post #52

> Vault lights were used to light some of New York City's first subway stations and were placed in the ground of the opulent passenger concourse in the city's original Pennsylvania Station. I will never get my head around the fact that the old Pennsylvania Station was destroyed. It must be one of the biggest mistakes in urban development of the 20th century. > Another architectural critic, Ada Louise Huxtable, wrote…

Interesting enough the glass floor was never removed during the demolition of the original Penn Station and can still be seen from the track level. Of course the floor has been tiled over and no longer functions as a light source, but it serves as a hidden reminder of the old Penn Station. https://ny.curbed.com/2018/10/23/18009496/penn-station-new-y...

Seems like some New Yorkers ought to petition to un-tile-over the floor and bring back the glass.

Re: What are those grids of glass in the sidewalk and why are they purple?

#92

Post by jdnenej »

BinaryIdiot wrote: post #72

This is fascinating. I've walked over those countless times and always wondered what they were. I am curious about this one bit though: > When vault lights were first installed, much of the glass was clear. But when the manganese is exposed to UV rays for long periods of time, it photo-oxidizes and turns purple or pinkish. Hence, the reason so much of the glass is now purple. > This process can take decades. So when…

I had no idea these were an actual thing. I just figured it was some whacky street decoration. The ones in Adelaide, Australia are mostly cracked and ruined and seem to be filled in with concrete when they break. I wonder if everyone decided it's easier to use electricity for lighting now.

Re: What are those grids of glass in the sidewalk and why are they purple?

#93

Post by blntechie »

hinkley wrote: post #8
taeric wrote: post #2

I thought this was going to be in Seattle. :) It is neat to notice these all over the place. The underground tour is more than a little crazy to see just how built up the city literally is. My favorite related topic were the spite mounds.

I think the Seattle Tour has a bunch of factoids of which each guide chooses their own subset. First time I took the tour, they mentioned that a bunch of the material for raising the streets came from San Franscisco, which had quite a thirst of lumber (and would occasionally catch fire and burn down, boosting that demand). Flat bottom boats hold a lot of bulky cargo, but they're a nightmare when empty. So on the retu…

When I first learned about raising the streets at massive scale in American cities (Chicago Seattle etc.), I was very fascinated. I’m not sure if this is/was an unique American exercise.

Re: What are those grids of glass in the sidewalk and why are they purple?

#94

Post by goodcanadian »

im3w1l wrote: post #19

One thing I would have liked the article to explain is when this is preferable over solid glass.

The individual pieces were shaped to diffuse the light so that regardless of the direction of the sun, you get a more or less uniform glow inside. This is much easier to do with multiple lenses/prisms than with a single large piece.

Re: What are those grids of glass in the sidewalk and why are they purple?

#95

Post by Cougher »

chrisseaton wrote: post #62
lqet wrote: post #52

> Vault lights were used to light some of New York City's first subway stations and were placed in the ground of the opulent passenger concourse in the city's original Pennsylvania Station. I will never get my head around the fact that the old Pennsylvania Station was destroyed. It must be one of the biggest mistakes in urban development of the 20th century. > Another architectural critic, Ada Louise Huxtable, wrote…

> the old Pennsylvania Station It wasn't that old! It was only built in 1910, and using modern techniques! It wasn't an ancient monument as you probably think it was, and it was only around for a few decades. Equivalent of a 1960s building being knocked down today.

"Equivalent of a 1960s building being knocked down today."

I feel like you refuted your first sentence with this!

Re: What are those grids of glass in the sidewalk and why are they purple?

#96

Post by Cougher »

ehnto wrote: post #90
lqet wrote: post #52

> Vault lights were used to light some of New York City's first subway stations and were placed in the ground of the opulent passenger concourse in the city's original Pennsylvania Station. I will never get my head around the fact that the old Pennsylvania Station was destroyed. It must be one of the biggest mistakes in urban development of the 20th century. > Another architectural critic, Ada Louise Huxtable, wrote…

Lost craftsmanship and cost of construction has risen so much that some projects just couldn't be afforded anymore. My city once had an extensive rail network, it was torn out in favour of cars. Now that we want to put it back in, construction costs are so inflated we can't afford it.

If it's in America, it isn't a matter of not being able to afford it; we choose not to, instead prefering to waste it on military spending. Our country really could be great again if we chose to stop that madness.

Re: What are those grids of glass in the sidewalk and why are they purple?

#97

Post by subroutine »

Cougher wrote: post #95
chrisseaton wrote: post #62

Earlier quoted context omitted.

> the old Pennsylvania Station It wasn't that old! It was only built in 1910, and using modern techniques! It wasn't an ancient monument as you probably think it was, and it was only around for a few decades. Equivalent of a 1960s building being knocked down today.

"Equivalent of a 1960s building being knocked down today." I feel like you refuted your first sentence with this!

A 1960s building is old, but 80 years isn't really enough to inspire awe; there are plenty of existing structures several hundred to several thousands of years old.

https://en.m.wikipedia.org/wiki/List_of_oldest_known_survivi...

Re: What are those grids of glass in the sidewalk and why are they purple?

#98

Post by Piskvorrr »

blntechie wrote: post #93
hinkley wrote: post #8

Earlier quoted context omitted.

I think the Seattle Tour has a bunch of factoids of which each guide chooses their own subset. First time I took the tour, they mentioned that a bunch of the material for raising the streets came from San Franscisco, which had quite a thirst of lumber (and would occasionally catch fire and burn down, boosting that demand). Flat bottom boats hold a lot of bulky cargo, but they're a nightmare when empty. So on the retu…

When I first learned about raising the streets at massive scale in American cities (Chicago Seattle etc.), I was very fascinated. I’m not sure if this is/was an unique American exercise.

Medieval cities used to do this; essentialy a transition from a small town to an actual city, i.e. "we are no longer able to fit the place to nature, let's do the opposite thing then."

Re: What are those grids of glass in the sidewalk and why are they purple?

#99

Post by Piskvorrr »

BinaryIdiot wrote: post #72

This is fascinating. I've walked over those countless times and always wondered what they were. I am curious about this one bit though: > When vault lights were first installed, much of the glass was clear. But when the manganese is exposed to UV rays for long periods of time, it photo-oxidizes and turns purple or pinkish. Hence, the reason so much of the glass is now purple. > This process can take decades. So when…

Perhaps any of these, depending on the materials. Color stability in the long run is rarely a concern.

Re: What are those grids of glass in the sidewalk and why are they purple?

#100

Post by Scarblac »

aclatuts wrote: post #5

I always thought it would be interesting to build vertical greenhouses with something like this, in the floors or walls, siphoning natural light between the floors

Modern greenhouses are often fully automated and have no need for floors.
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