The textual transmission of the Corpus Agrimensorum Romanorum, the collection of Roman land surveying treatises, is notoriously difficult. An attempt is made to remedy this situation for two treatises which are ascribed to Marcus Iunius Nypsus and which are of importance for the history of both surveying and of mathematics. On the basis of a renewed study of the relevant manuscripts a new text edition is presented. Next the first complete translation of both treatises is given. Finally, the problems related both to the textual transmission and to the interpretation of the text are dealt with.