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What are those grids of glass in the sidewalk and why are they purple?
- taeric 7y agoI 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.
- hinkley 7y agoI 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 return trips they ballasted them... with fill dirt.
- vineyardmike 7y agoThat tour is great! I take everyone who visits seattle to it. I've had the same tour guide, and each time was different as well.
- nogabebop23 7y agoSlightly off-topic; The Seattle free walking tour (pay what you want after) is also great, epsecially for a first time visitor. My wife and I happily shelled out after the 2-hour version.
- blntechie 7y agoWhen 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.
- Piskvorrr 7y agoMedieval 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."
- tehwalrus 7y agoSee also Rome, which is built on top of about eight more layers of Rome. Residents often get architectural and history students asking to look at something weird in the basement.
- pkamb 7y agoThe new Seattle waterfront sidewalks have a similar inlayed motif of large purple glass tiles. Was cool to notice the design inspiration. https://www.washington.edu/news/2017/05/18/seattle-seawalls-novel-fish-features-are-a-potential-model-for-the-world/ https://www.washington.edu/news/2017/05/18/seattle-seawalls-... https://www.kuow.org/stories/seattle-s-new-seawall-was-built-for-fish https://www.kuow.org/stories/seattle-s-new-seawall-was-built...
- rconti 7y agoI grew up in Seattle. I still need to do the tour some day when I visit. So many cities have underground tours and I've heard great things about them.
- meddlepal 7y agoI did it last time I was out there..., I had fun and some time to kill before my flight. The tour guide makes the tour interesting. The actual sights are cool but you're effectively on a guided tour through maybe a few small blocks of buried sidewalk. It is not earth shattering stuff though the history is definitely cool. In the end it was worth the ~$40, $20 for the tour I think, and I felt generous so I gave the guide a big tip since he was hilarious and took us on a slightly extended route according to some folks who had done the tour in the past.
- deleted 7y ago[deleted]
- thematt 7y agohttps://mashable.com/2015/08/18/building-seattle/ https://mashable.com/2015/08/18/building-seattle/
- philwelch 7y agoIf you've already done the normal underground tour, there's also a late-night version where they talk about the seedy underbelly of early Seattle, i.e. all the prostitution and body-snatching and other assorted crimes. Or at least there used to be one.
- taeric 7y agoThey mentioned a bit of that on our tour. With kids ranging from 5 to 10, it was kind of funny to see the looks. (My kids, to be clear.) I got the impression it wasn't much of an under belly, as it was a large part of the life around here.
- AstroJetson 7y agoI had a sail boat where the prior owner had installed 4 of these in the cabin roof. They were little domes and did a good job of lighting the cabin in the day, and marking a path at night.
- hinkley 7y agoI learned about these many years ago, but the whole "you can see a fire in the hold" angle never occurred to me. Accurate, useful, and macabre.
- sandworm101 7y agoA watchman on deck could also see if a thief is rummaging around down there while the boat is in port.
- odonnellryan 7y agoYes had one in my old boat. Nice, but not so nice where I'd install them on my current sailboat.
- dcminter 7y agoPerhaps the inspiration behind this? https://www.bbc.com/news/magazine-23536914 https://www.bbc.com/news/magazine-23536914
- Semiapies 7y agoPossibly, or an independent invention from first principles; you'd have to ask the guy.
- egypturnash 7y agoThe article makes it sound like he came to it separately from just playing around with light refraction in water, using an easily-available container.
- aclatuts 7y agoI 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
- Scarblac 7y agoModern greenhouses are often fully automated and have no need for floors.
- altgeek 7y agoIn downtown NYC, there still are areas of sidewalk with these.
- abuckenheimer 7y agoJust remembered the puck building[1] has these on the sidewalks surrounding the Houston street side, if you go into the Eastern Mountain Sports store and down the stairs you can see them from below. [1] https://en.wikipedia.org/wiki/Puck_Building https://en.wikipedia.org/wiki/Puck_Building
- robk 7y agoThese are ubiquitous in London
- iDemonix 7y agoAnd many other parts of the UK. I've seen a fair amount in both Oxford and Nottingham.
- NeedMoreTea 7y agoPlenty up north too. Don't ever remember seeing a purple one though, pretty much always the green you'd expect of very thick glass.
- oneeyedpigeon 7y agoNotably the ones in Crystal Palace [1] which are above an old underground toilet, now converted into someone's house! [2] I guess — in this case, at least — the fogging-up of the glass is actually a privacy feature. [1] http://1.bp.blogspot.com/-SuRJ4LN5LhQ/T3GQS8rUN9I/AAAAAAAAAMo/GkBQCh0GctM/s1600/external+complete.jpg http://1.bp.blogspot.com/-SuRJ4LN5LhQ/T3GQS8rUN9I/AAAAAAAAAM... [2] http://crystalpalacetoilets.blogspot.com/ http://crystalpalacetoilets.blogspot.com/
- jaclaz 7y agoOnly for the record, there is a "modern" material, called "glass block" since the '50's or '60's, the one in your photos seem like it (and there is no "prism" like the kind described in the main article) that can be used also for walls. Example: https://www.sevesglassblock.com/wp-content/uploads/2018/03/Technical_Guide_en.pdf https://www.sevesglassblock.com/wp-content/uploads/2018/03/T... (go to page 54 of the .pdf)
- b5 7y agoLots of them all over Scotland, too.
- deleted 7y ago[deleted]
- RangerScience 7y agoOh neat! I didn't know that Sacremento has this kind of underground. Also, anyone else having flashbacks to Dinotopia sunstones?
- SubiculumCode 7y agoIndeed. I've been living in the area for some time now and had no idea. I wonder if there is some area that can be explored?
- daxorid 7y agoThis is interesting, but raises a question. The article mentions: In San Francisco, vault lights are mostly used to illuminate sub-sidewalk basements — ie. basements that extend under the sidewalk. How does this work, legally? Where I live, sidewalks are property of the city (or the HOA, in some cases), and I'd presume the same in SF. Does the title of the sidewalk-adjacent property allow you to excavate N feet beyond the property line? Or is the sidewalk instead a publicly-managed easement on your own property? Who pays for installation and maintenance of the vault lights? How does coordination of engineering/construction of the sidewalk-basement boundary work?
- vidanay 7y agoI would guess these situations pre-date any of the current zoning laws.
- dualboot 7y agoThis is correct.
- Digory 7y agoIt depends on how the lines are drawn. If you want to plow a road through existing houses today, it gets condemned -- taken by the government, lock, stock and barrel. In a new subdivision, they'll often deed the streets over to the city. But sometimes, especially in the old days, the city just got a "right of way," not title to the land. And in that case, the owner could do anything it wanted, so long as it preserves the right of way. So if the city had a right of way to a sidewalk, it doesn't matter what you do under the sidewalk. Here's an interesting discussion about right of way edges that appears to use Washington (State) law.[0] [0] http://mrsc.org/Home/Stay-Informed/MRSC-Insight/November-2017/Understanding-Municipal-Rights-of-Way-From-Center.aspx http://mrsc.org/Home/Stay-Informed/MRSC-Insight/November-201...
- yardie 7y agoThat must be a western concept. On the east coast it's common for sidewalks to be owned by the landowner yet have to remain unencumbered for the public right of way. Some owners find out the hard way that they are also responsible for maintaining the sidewalk when the city hits them with a notice.
- glangdale 7y agoThaddeus Hyatt, the inventor of those grids, has a fascinating history, including backing militant abolitionists (I think it's unknown whether he bankrolled John Brown) and being jailed by the Senate (?) for refusing to testify.
- brlewis 7y agoWikipedia states his financial support of John Brown as fact: https://en.wikipedia.org/wiki/Thaddeus_Hyatt https://en.wikipedia.org/wiki/Thaddeus_Hyatt
- bynkman 7y agoI know of a few places in Kansas City that have under sidewalk vaults. In some of those places they have warning signs about not parking. Here's one. https://bit.ly/36qPLvy https://bit.ly/36qPLvy
- im3w1l 7y agoOne thing I would have liked the article to explain is when this is preferable over solid glass.
- vineyardmike 7y agoPresumable cost or manufacturability? Big sheets of glass were not feesible in the 1800s
- myself248 7y agoTempered glass is relatively modern. They didn't have strong solid single panes of glass back then; the concrete with glass inlays was the best way to make it stand up to traffic above.
- WorldMaker 7y agoSafety/stability, presumably, given that people might stand on top of them (many of the examples here are embedded in sidewalks) and they'd need to be weight bearing. Safety glass is a relatively more recent invention than some of the examples (at least one example in the article dates back to the mid 19th century), and a very recent invention if specifically restricting to the types of plastic-based laminated glass trusted in things like modern car windshields and observation floors today.
- WorldMaker 7y agoAlso, the article points out that many of them had interesting prismatic shapes to bounce light around in interesting directions, and making those prisms would be easier as smaller individual components rather than one large piece of glassblowing, even if they had the technology to make it safe enough at that size.
- DanBC 7y agoThe earliest patent of deck lights, which predate vault lights or sidewalk prisms, is from 1684. This site includes some images and patents https://glassian.org/Prism/index.html https://glassian.org/Prism/index.html There's a patent for sidewalk prisms from 1834. As other people have said, the glass broke. > In 1834, Edward Rockwell patented a round iron plate with a single large lens, but Hyatt later complained in his own patent application, "These glasses are extremely liable to fracture, and when broken leave large and dangerous openings within their rims...". Rockwell's plates are rare today; I know of only three examples of the iron covers and none of the lenses
- StClaire 7y agoDenver has these, you can see them on Larimer and Market street in LoDo. Around the 1890s, the locals dug out a series of tunnels through the city. The snows would come in and people would just go underground for a few days for business. There was a bar that closed about a year ago called the Blake Street Vault—it used to be a bank—and if you asked they would take you into the basement to see the vault and the dumbwaiter. You can see down where they plastered over some of the wall, it used to have a teller window right there open to the tunnels for customers. Supposedly, you could go from Union Station all the way to the capital building underground (but I doubt that). I’m sure most of the tunnels aren’t passable, possibly collapsed, filled in, or flooded. But I seriously want to go down and try to map out some of them to be restored like they did in Seattle.
- rconti 7y agoStupid question: Wouldn't the snow cover the vault lights? (I know, they could clear them by clearing the sidewalks...)
- jrace 7y agoIt would. But not 100%. Same with skylights, depending on the depth and density some sunlight still makes it
- sampo 7y agoSnow also scatters light a lot, if it's not too dirty. One example I found, it takes about 8 cm (3 inches) of snow to reduce the light irradiance to half.
- jrochkind1 7y agoThey weren't clearing the sidewalks to let light through, they were (and we are) clearing the sidewalks so that people could walk on them! Anyway, with or without prism tiles.
- lozaning 7y agoI've got some friends in Minneapolis that November - ~May don't leave the skyway system. Seems similar, but connects buildings at the 2nd story instead of underground. http://www.skywaymyway.com/ http://www.skywaymyway.com/
- ilammy 7y agoModern people accustomed to ubiquitous electrical lighting would probably think of 19th century and beyond as quite dark.
- sandworm101 7y agoIt was. Very dark. The changes brought by electric light cannot be overstated. In my lifetime, LEDs brought portable light in the outdoors from an expensive and dangerous luxury (candles, lanterns etc) to something innocuous and expected. Camping and working outdoors today is totally different than even 25 years ago.
- kaybe 7y agoThe house we live in (from 1903) still has the original gas lines everywhere. That means there is a hook in the middle of the ceiling connected to the gas pipes for you to hang your gas lantern, but also one or two wall outlets in every room for those. I suppose the neighbouring houses all had those de-installed, but our electricity installation is from ~1930 as well, so the owners were never fond of renovations, it seems. (It works surprisingly well for its age.) I often wonder about the people who lived here and their lifestyles.
- huangc10 7y agoI walk past these all the time thinking they're just interesting design patterns on the floor...how dumb of me. Insightful article and fun read.
- ndesaulniers 7y agoEureaka in Mountain View, CA, across from Red Rock Coffee Shop, anyone?
- austinjp 7y agoThe Wikipedia entry on prism lighting is... illuminating: https://en.m.wikipedia.org/wiki/Prism_lighting https://en.m.wikipedia.org/wiki/Prism_lighting
- dammitcoetzee 7y agoThis article is fantastic and answers a lot of questions I didn't know I had!
- djmips 7y agoIs this is the same thing but at a larger scale than the light diffusion used in flat panel displays?
- agumonkey 7y agointeresting, lest reuse old batteries manganese dioxide and remelt glass bottles :)
- Angostura 7y agoLots in London, and many very old - but I've never spotted purple ones.
- coolblah 7y agoResearch mudflood to go way down this rabbit hole.
- lqet 7y ago> 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 in The New York Times in 1963: "The tragedy is that our own times not only could not produce such a building, but cannot even maintain it." [0] https://upload.wikimedia.org/wikipedia/commons/6/60/Penn_Station_interior.jpg https://upload.wikimedia.org/wikipedia/commons/6/60/Penn_Sta... https://upload.wikimedia.org/wikipedia/commons/3/39/NYP_LOC5.jpg https://upload.wikimedia.org/wikipedia/commons/3/39/NYP_LOC5... https://upload.wikimedia.org/wikipedia/commons/thumb/d/d9/South_facade_from_southeast_-_pennsylvania_station.tif/lossy-page1-1280px-South_facade_from_southeast_-_pennsylvania_station.tif.jpg https://upload.wikimedia.org/wikipedia/commons/thumb/d/d9/So... https://upload.wikimedia.org/wikipedia/commons/f/f8/The_New_York_improvement_and_tunnel_extension_of_the_Pennsylvania_railroad._Issued_October%2C_1910_%281910%29_%2814573203608%29.jpg https://upload.wikimedia.org/wikipedia/commons/f/f8/The_New_... https://live.staticflickr.com/5085/5383028384_a22f3605e4_b.jpg https://live.staticflickr.com/5085/5383028384_a22f3605e4_b.j... https://static01.nyt.com/images/2019/04/24/lens/24pennnstation-ast-5/merlin_148714782_bb4b9b98-bded-4d9d-b4e6-f2a13d819201-superJumbo.jpg https://static01.nyt.com/images/2019/04/24/lens/24pennnstati... [0] https://en.wikipedia.org/wiki/Pennsylvania_Station_(1910%E2%80%931963)#Demolition https://en.wikipedia.org/wiki/Pennsylvania_Station_(1910%E2%...
- chrisseaton 7y ago> 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.
- inferiorhuman 7y agoEquivalent of a 1960s building being knocked down today. There are plenty of buildings from the 60s I'd be sorry to see go. At the top of the list is the Marin County Civic Center and the TWA Flight Center.
- 8bitsrule 7y agoLooks as though these might be most common in older port cities. I first saw them in Duluth (the tip of Lake Superior) but not in other cities in the region. Possibly the vault-light salesmen travelled by ship a lot!
- zbentley 7y agoThey look like "Dinotopia" Sunstones.
- adrianmonk 7y agoOr "Land of the Lost" crystals: https://landofthelost.fandom.com/wiki/Crystals https://landofthelost.fandom.com/wiki/Crystals especially as seen in matrix tables in the pylons: https://landofthelost.fandom.com/wiki/Pylons https://landofthelost.fandom.com/wiki/Pylons
- BinaryIdiot 7y agoThis 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 you see colored glass, it’s either really old or someone dyed it to mimic the old glass. So what happens to dyed glass after decades? Does it have a deeper purple? Is it made out of materials that _won't_ change color? Something else?
- EB66 7y agoIIRC maganese was used by virtually all American glass manufacturers from the 1800s til 1920ish. So I suppose if the glass was dyed purple, it would turn more purple as it was exposed to UV but only if the glass was manufacturered during that time period.
- jdnenej 7y agoI 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.
- eskaytwo 7y agoWhere are they in Adelaide?
- Piskvorrr 7y agoPerhaps any of these, depending on the materials. Color stability in the long run is rarely a concern.
- jacquesm 7y agoThat depends on the application. In stained glass and other glass used for art color stability is very important in the long run.
- jedberg 7y agoIf you’re ever in Seattle and this kind of thing fascinated you, I highly recommend the downtown underground tour. This is one of the things they cover.
- markstos 7y ago"Hyatt’s innovation in subterranean lighting made him rich as his vault covers were used all over the country. With his newly acquired wealth he spent much of the rest of his time and money fighting for the abolition of slavery."
- loeg 7y agoYou see these around the south end of downtown Seattle too.
- evanthayer 7y agoI restored many old cast iron buildings in NYC that used “bullet glass” paving for the sidewalk above the vault below. These are still manufactured by Circle Redmont (approved by NYC Landmark Preservation Commission) and are beautiful but expensive.
- ChuckMcM 7y agoI really love these, there was a story about a modern version here: https://www.youtube.com/watch?v=tJD-D2uLX70 https://www.youtube.com/watch?v=tJD-D2uLX70 where African's use plastic bottles filled with water as vault lights.