This old, Roman goniometer (Latin: shell or bowl) was, along with the sextarius, one of the most widespread standard measures in ancient Rome. Liquids were originally calculated by weight. The largest known room measure was the culleus (= leather sack, tube) comprising 160 congii and containing 524 litres, i.e. about two barriques. The amphora (26.25 litres) was used as a commercial measure and was divided into two urna (of about 13 litres). The sixth part of a congius was called a sextarius, corresponding to 0.54 litres and was a schoppen or jug in today's terms. The third part was called triens with 0.18 litres, the fourth part quadrans with 0.135 litres, the sixth part sextans with 90 cm³ and the twelfth part the cyathus (scoop) mentioned in the novel Satyricon with 45 cm³. The list brings the most important hollow dimensions in relation to each other (but there were many more). The measurements are not necessarily compatible with each other and should only be understood as guidelines. On the subject of units of measurement, see the lists under the keywords barrel types, bottles, gauges and wine vessels.