“Concrete was one of the most exciting products of the nineteenth century. As a material, it had been around for a very long time—the great dome of the Pantheon in Rome is made of concrete; Salisbury Cathedral stands on concrete foundations—but the modern breakthrough for it came in 1824 when Joseph Aspdin, a humble bricklayer in Leeds, in the north of England, invented portland cement, so called to suggest that it was as attractive and durable as portland stone. Portland cement was vastly superior to any existing product. It even performed better in water than the Reverend James Parker’s Roman cement. How Aspdin invented his product has always been something of a mystery, because making it required certain precisely measured steps—namely, pulverizing limestone to a particular degree of fineness, mixing it with clay of a specific moistness, and baking the whole at temperatures much higher than would be found in a normal lime kiln. None of this was ever going to be hit upon by chance. What gave Aspdin the hunch to alter the constituents as he did and then to conclude that they would make a product that would set harder and smoother if heated to an extreme degree is a puzzle that cannot be answered, but somehow he did it and it made him rich. Bryson, Bill. At Home (p. 323). Knopf Doubleday Publishing Group. Kindle Edition. Bryson, Bill. At Home (pp. 322-323). Knopf Doubleday Publishing Group. Kindle Edition. ”