The History of 19th & 20th Century Vault Lights (prism glass used in sidewalks) used in Illinois Towns and Cities.

Vault Lights, also known as Sidewalk Lights (or Pavement Lights in the UK), are those old glass prisms set into sidewalks to let light into vaults and basements below. Prisms were used instead of flat glass to disperse the light, diffusing it over a large area; plain flat glass would simply form a bright spot on the floor below, not providing much useful general lighting. 

Cross-cut of Basement using Vault Lights.

Invented in 1845 by Thaddeus Hyatt, sidewalk vault lights started being used in urban areas beginning around the 1850s and continued to be popular into the 1920s. The first vault lights were engineered to have glass blocks placed into a cast-iron framework.

Later, with the introduction of Portland cement, setting them into reinforced concrete panels was more common.

These “glass blocks” provided a way to get light into the useful basement and void areas under the sidewalks. This also made the space rentable in some cases. The first attempts at vault lights proved unfruitful because the design basically allowed a single shaft of light to shine straight down into the space below.

Marshall Field Vault Lights on State Street, Chicago.

With Hyatt’s invention, the design incorporated a prism shape (“saw-tooth”) on the underside while the surface above remained smooth to walk across.

This provided a way for the light to be directed over a broader area in the dark underground.

 

The idea caught on; by the late 19th century they were common in larger cities downtown areas, especially cities like Chicago, New York, and San Francisco. Their use declined as electric light became cheaper and better, and by the 1930s they were not considered in construction any longer. 

Now, they are now endangered architectural relics.

Vault lights on the second floor of the atrium of The Rookery Building, Chicago.

Chicago locations where prism glass installations were known to exist (via Google Map).

Compiled by Dr. Neil Gale, Ph.D.  

Glass Blocks; a Chicago Invention for the 1893 World's Columbian Exposition.

Glass block, or glass brick, has an interesting history and connection to Chicago via two Chicago World's Fairs and multiple Chicago-based companies.

Gustave Falconnier
Glass Designer

The 1893 World's Columbian Exposition is known for introducing many things to the United States. One lesser-known first at the World's Fair showed the United States the first glass bricks made by Gustave Falconnier. 

Falconnier, an architect, Chicago city council member, prefect of Nyon, France, and a graduate of the Ecole des Beaux-Arts in Paris, held many patents in the 1880s for various types of glass blocks of interesting geometric shapes.

At the Columbian Exposition, Falconnier exhibited his glass in buildings outside the Horticultural Building, showing their potential uses in architecture and horticulture. Falconnier was awarded by the fair commission for "a new departure in glass buildings."

Despite being shown in the horticultural pavilion, the fair commission gave him a somewhat backhanded compliment, saying, "Their adaptability for conservatories intended for plant cultivation has not yet been fully demonstrated, but for conservatory vestibules and other rural effects, they are well adapted." And finally, "In the construction of surgical, photographic, and other experimental laboratories, where extra subdued light is required, they possess great merit."

The Northern Pavillion of the Horticultural Building and Exhibit of Hot-Houses and Summer Houses.

Falconnier's glass block had a flaw that prevented it from taking hold in America. Because they were blown glass, the blocks needed a hole. Even a tiny hole eventually plugged up, leading to fogging. Once fogged, the bricks would need to be replaced. A tall order indeed for something that is meant to be permanently put into a wall.

Glass Block would get a second chance at Chicago's Century of Progress International Exposition in 1933 before it took hold in US architecture. However, other types of architectural glass that would be formative to the glass block's future were taking shape in Chicago.

The popularization of Art Deco glass block walls came via the crowd-pleasing thirteen houses of the future displayed at the 1933–34 Chicago World's Fair. Glass block walls gave builders an avant-garde 20th-Century sensibility that people really liked.

At the time, the Chicago World's Fair buildings were considered the height of American modernity and influenced United States architectural design for many years. The Century of Progress, planned before the crash of 1929, opened in the middle of a worldwide economic crisis. Despite that fact, or perhaps because of it, the Century of Progress resolutely focused on an optimistic vision of the United States yet to come, a premise that proved to be a wise move as it attracted so many visitors that organizers kept the fair open for a second year.

Owens-Illinois exhibit at the Chicago Century of Progress International Exposition, 1933-34.

Keck's design, which the Fair billed as the "House of Tomorrow," made the June 1933 cover of Popular Mechanics.

One of the Fair's most popular exhibits featured thirteen futuristic houses clustered together on the shores of Lake Michigan. Those houses, built from innovative construction materials and with several examples clearly paying homage to the European "International Style" or the colloquial "Streamline Moderne," turned out to be a crowd-pleaser. 

Few fairgoers actually contemplated living in homes like George Fred Keck's Glass House, a three-story, glass-clad, polygonal tower suspended from a central pole that clearly owed a lot to Le Corbusier's idea of the house as a "machine for living," but most attendees marveled at the technology displayed within and without. 

Keck's house controlled its own climate via central systems and sealed windows. It included a garage for the car and a hanger for the family plane. Keck's design, which the Fair billed as the "House of Tomorrow," made the June 1933 cover of Popular Mechanics. The idea of an "automatic" house that heated and cooled itself, rotated to face the sun and opened its own Venetian blinds caught the fancy of fairgoers. It likewise influenced architects throughout the United States in the subsequent years before World War II. Bits and pieces of the Fair's dramatic architecture appeared on the cultural periphery. 

Compiled by Dr. Neil Gale, Ph.D.