Temple of Jupiter, Serapis, Italy, 1836.
© Science Museum / Science & Society Picture Library
When excavations began in 1750, a statue of the Egyptian god Serapis was found, leading to the building's mistaken identification as a temple. Now known as the Macellum, it was actually part of a market, contained lavatories and was posibly used for thermal functions. The Macellum serves as a method for measuring the bradyseismic phenomenon: corrosion on the columns caused by lithophagi (date musels), indicates the different water levels over time. This led mathematician Charles Babbage (1791-1871) to conclude that the 'subsidence of the building was not sudden, or at one period only, but gradual, and by succesive movements.' Illustration from Babbage's 'Observations on the Temple of Serapis at Pozzuoli near Naples', published in 1847.