Opus spicatum, which translates to “spiked work,” were small ceramic bricks the Romans laid in a herringbone pattern for pavement. Remains of such work can be found in many areas of the world even today. When aligned in this pattern, they are nearly impervious to foot traffic. According to Will Belcher, in Opus spicatum: A History of Herringbone, “when the chevrons are pointed in the direction of traffic the pattern becomes extremely strong under compression as the chevrons are able to spread the load over twice as many bricks. This inherent ability to absorb compression of movement makes it a remarkably resilient paving pattern.” Such technology was lost after Rome fell, though, and not rediscovered till much, much later in history. Belcher states that when opus spicatum was rediscovered,
the herringbone bond was taken from the horizontality of landscape and began to find its self in the motifs of architecture. The pattern became the fundamental backbone of Brunelleschi’s great Duomo in Florence. By incorporating the interlocking pattern into the structure of the dome, much like keystones in an arch, Brunelleschi disposed of the need for a central support system. The interlocking system gave the dome its unique shape and allowed it to defy the rule of quinto acuto, or ‘acute fifth,’ a mathematical concept that had previously been used to divine the curvature of architectural domes.
Because the opus spicatum is part of the dome’s infrastructure, the sections with the brickwork cannot be seen by the casual viewer. So, I’m very happy to have come across photos that show the masonry in the article “The Great Dome of Florence” in Counterlight’s Peculiars. Just scroll down the page till you reach it.
Opus spicatum in the face of the church Savennières, in Loire Valley, France. By Kormin via Wikimedia Commons










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