Thursday, May 31, 2018

Libella, Leveling Tool

Roman architects were skilled in this kind of leveling work, for which they used sophisticated tools. Besides the ordinary level (Libella), similar to the one used today by carpenters, they used devices such as a groma, chorobates, and dioptra.
Given the elementary means, materials en tools which were available, it is remarkable to see the precision with which the Roman aqueducts were laid out. The mean gradient of a Roman aqueduct was something between 0,15 - 0,30 %.
Additional resources
Another leveling instrument used by the Romans was the simple "Libella." It consisted of a frame in the shape of the letter A, with the addition of a horizontal bar on top (see photo). From the apex, a plumb line was suspended that coincided with a mark on the lower crossbar when the instrument was level. Other marks could have been added to indicate other slopes, but there is no evidence that this was done (Hauck, 1988:43).
> Moreno (2004): Roman Surveying (from the Spanish Traianus website)
> M.J.T. Lewis (2001): Surveying Instruments of Greece and Rome
> O.A.W. Dilke (1971): Roman Land Surveyors
Roman military surveying, from YouTube

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