A walk-on glass floor cannot help but take one’s breath away, as they are often fitted about areas of architectural, archaeological or aesthetic interest, as well as inviting more light throughout a building.
They are typically thought of as a relatively modern design element, in no small part because truly indestructible walk-on glass using advanced tempering and lamination techniques is relatively new.
However, the need for it is far older than one may expect. In the late 19th century, glass-bottom boats were already being used to give tourists a look at aquatic life at the bottom of various rivers, springs and lakes in Florida.
Even earlier than that, the concept of glass clear enough to see through but strong enough to walk on was highly desired, but without modern strengthening techniques, a fair degree of lateral thinking and imaginative problem-solving was needed.
Pavement Pebbles
In the early 19th century, a lot of newly industrialised towns and cities started to build higher, typically by raising the street level and creating tunnel networks in the process.
These spaces could and were often used, taking the form of vaulted pavements and area spaces. The only problem was that their underground nature meant that they were pitch black, and the only common source of light was too dangerous to use for long periods of time underground due to gas fumes.
The most common solution was the simplest; fit parts of the pavement above with gratings that allowed for a lot of light to trickle down into the basement area, but this simplicity also came with many fundamental flaws.
As they were essentially storm drains fitted to the pavement, they very quickly became rather dangerous trip hazards, and often let a lot of water from street level back into the underground area, somewhat undermining the efforts to avoid flooding in the first place.
Thankfully, by the 19th century, glass was becoming a potential solution, with tools and techniques available to make progressively bigger, albeit still somewhat weak plates.
The first solution was the deck prism, a form of strong prismatic glass designed to reflect natural light into the lower decks. In the mid-1840s, a design patented by Edward Rockwell saw them fitted to an iron frame and fitted in the same types of places the grates previously sat.
The concept worked and proved the importance of glass floors to act as a skylight, but there was a tremendous problem with this original design.
It was fitted with the prism shape facing down, which whilst necessary to refract the light as much as possible meant that the entire frame was bottom-heavy, causing it to easily break and fall.
Once it had fallen there was a huge gap in the street which could potentially cause a trip or fall hazard.
This eventually led to legal rulings that such glass sections could only be 10cm by 10cm in size, not big enough to truly serve as walk-on glass.
Designers of the era such as abolitionist Thaddeus Hyatt worked around these limitations by designing the pavement lights for the needs of the pedestrian above, protecting the glass from damage and ensuring they were still safe to use even if all the lenses broke.
This eventually inspired the creation of tougher glass systems and glass panels designed to be strong enough to walk on for long periods of time.