Walking among the Doric columns of the Parthenon in Athens or in the magical Valley of the Temples in Agrigento, it is easy to be fascinated by the seemingly perfect harmony that characterizes them. But, looking carefully, you realize that these columns are not completely straight: they have a subtle curvature, the entasis. This optical correction technique involves a slight swelling to compensate for a perceptive effect of our eye, but it is not just a refined aesthetic expedient: far from being a simple architectural illusion, entasis has in fact much deeper engineering bases. Recent studies reconfirm that the particular shape with the entasis makes the columns not only more elegant, but above all more robust and lighter, a realization of ancient technical wisdom finally understood today.
According to the study by a group of researchers from New York University, entasis may not serve so much to correct an optical illusion or have an exclusively aesthetic function, but rather it could be an engineering choice. The idea that entasis was used for engineering reasons has a long history: already in 1773 the mathematician and astronomer Joseph-Louis Lagrange proposed that it served to increase the resistance of a column. The mathematician Joseph Keller (1960) demonstrated that the strongest column is not cylindrical, but rather tapered along its length, being thicker in the center and thinner at the ends: this shape, according to him, determines a buckling load that is 61.2% greater than that of a cylinder. Recent work by mathematician Steven Cox (1992) has shown that a “stunted cycloid” is stronger than a cylindrical column of the same length.
According to this theory, also confirmed in more recent studies, the optimal shape of a column is precisely the one with entasis, which would make the columns lighter with the same compression force.
The entasis, therefore, may not be the result of a refined optical game nor a simple aesthetic quirk, but the testimony of a profound constructive intelligence. Those masters of the past, guided perhaps more by experience than by theory, had intuited that a slightly arched column could better support the weight of the world. Today science confirms what human ingenuity had already intuited centuries ago: in the slight curvature of the Doric columns hides a perfect balance between beauty and strength, proof that for the Greeks art and technique were, ultimately, a single form of wisdom.
