sidewalk glass blocks
Yesterday's glass block lights remind me of the heavy glass block panels let into sidewalks that provided light to cellar spaces under the pavements. Haven't seen these for years, although they were once very common, and in looking around for pictures found lots of websites about their preservation. The Ringuettes have a good site on the sidewalk glass prisms of Victoria BC where all the downtown sidewalks appear to have had lenses.
Glass prisms, either square or round, are set in structural metal frames and then the whole unit spans the sidewalk over the basement level storage or working space. They date from the early 1900s and are found extensively in old sections of cities that have either been preserved as historic districts or are so run down as to have escaped modernisation, which in sidewalk terms usually means concreting over the glass sections.
Originally clear glass, the manganese used in glass in the early 1900s has turned these lenses a deep amethyst with exposure to sun. I remember Victoria's glass sidewalks as being quite dark glass — but I've also seen glass panels in London that are white and shine brightly at night when the cellars below the sidewalks have their lights on. It was this that I thought of with the LED glass blocks.
The sense that downtown sidewalks are actually roofs, that the sidewalk is not ground beneath your feet but a hollow space in which people are working, registers a lovely kind of urban knowledge. In contrast, the total pedestrianisation of downtown streets such as 8th Avenue in Calgary, or Granville in Vancouver, where one can wander willy nilly from street wall to street wall as if the road was a creekbed at the bottom of two cliffs, where everything is up, lacks this sense that the pedestrian surface is a fragile skin between a shadowy underworld and a bright thrusting upperworld.
It also indicates an ambiguity of ownership and property: who owns that bit under the sidewalk? In cities obsessed with property and jurisdiction, such as Calgary, this ambiguity is not allowed. This is a city where corporate security patrols the edges where plaza meets sidewalk, where one cannot take photographs of the public sidewalk from a private-public plaza, or photos of the private-public plaza from the public sidewalk. The lines are hard here, the sidewalks concrete.