there are a lot of pavement lights (glass pavers allowing natural light to basement levels) in central Melbourne. they were most popular before the advent of inexpensive electric lighting but they're having a bit of a resurgence. these are on collins st
classic pavement light glass tiles (pre-electricity) are often flat-topped prisms. this allows them to scatter light into a wider area in the space below, rather than simply spotlighting the area directly below the tile
In Australia pavement lights are usually clear, but internationally, older pavement lights are often purple. they started out clear, but manganese dioxide, a common additive, becomes purple with long exposure to UV light. these photos are from Saskatoon
pavement lights were based on deck prisms in ships, which were embedded in the deck to give light to lower levels during the day without the danger of flames. they are still sometimes used today (mainly on fancy rich people boats)
the first pavement lights were one big glass prism. this was vulnerable to breakage and dangerous. in 1845, Thaddeus Hyatt (New York) patented the first pavement light with multiple small lenses sunk in an iron frame. this caught on and he became wealthy
Hyatt used the wealth from his pavement light invention to financially support the abolitionist cause; he was a patron of John Brown. after the Harpers Ferry raid he was jailed for three months for refusing to testify to the Senate
by the early 20th century, advances in glass block strength meant that a higher amount of the surface area of pavement lights could be glass. thus, contemporary pavement lights are more like skylights than deck prisms. (Collins St, Melbourne)
pavement lights (and glass blocks in general) seem to be having a bit of a resurgence as people search for ways to reduce electricity use. these pavement lights provide daylight to council offices in Woollahra, Sydney
please also check out this fabulously lo-fi and informative website by the glass collector known only as Glass Ian. every day our use of the internet drifts from this sort of website is a day we move further from God's (pavement) light 
the Albany Newsreel Theatrette was one of many similar theatrettes in 1930s Melbourne which were usually underground; note the pavement lights. following the rise of TV news they rebranded as the Albany Pussy Galore Cinema until they closed in 1989. 
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