Modern glass bricks were preceded by Falconnier Hollow Glass Bricks in the late nineteenth century. Falconnier Bricks were blown glass bricks available in multiple colors and were formed in molds while the glass was molten. An early 20th century summary of glass brick use: The Falconnier bricks could be used for walls or roofs and were joined together with wire and cement. The suggested use for Falconnier glass bricks was in greenhouse construction due to the non-conductivity of the glass for temperature control and lack of porosity of glass for moisture control. Falconnier bricks were touted for not tarnishing, trapping dust, or retaining water. Vault lights in sidewalks, which utilized prism lighting, were one of the first steps towards the modern hollow glass brick. At the end of the nineteenth century glass prisms became a popular way to diffuse light into spaces that would otherwise be difficult or unsafe to light via flame-based oil lamps (i.e. basements underneath sidewalks).