The "Elementa super demonstrationem ponderum" seems to be the one work which can definitely be ascribed to Jordanus; and the first of the series. Jordanus took what Joseph Brown has called the "Logician’s Abstract of "On the Karaston"" (a skillful compression of the conclusions of Thābit ibn Qurra’s "Liber karastonis") and created a new treatise (7 axioms and 9 propositions) in order to establish a mathematical basis for the four propositions on the Roman balance called the "Liber de canonio". An early commentary on this (which also contains a necessary correction to Proposition 9) is the “Corpus Christi Commentary”.